JP2009045642A - Welding apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a welding apparatus which can automatically and simply carry out the welding work for an aluminum pipe joint. <P>SOLUTION: The welding apparatus comprises an input section 101 for inputting welding conditions for a main pipe 3a and a branch pipe 3b to be welded, a three dimensional rotary table 1 which can turn about X-Y-Z axes, and changes the posture of a workpiece 3, rotary table driving sections 1a, 1b, 1c for driving the three dimensional rotary table 1, a welding torch holding section 2d for holding a welding torch 4 so as to point downward, and a control section 106 for controlling the rotary table driving sections 1a, 1b, 1c based on the information input from the input section 101. The coordinate positions of all welding positions 6 in an absolute coordinate system are calculated based on the information from the input section 101. The center line of the welding torch 4 is always positioned on the XZ plane of the absolute coordinate system. Further, when the line segment made by the present welding position 6 and the next welding position 6a is taken as a welding line 7, the rotating conditions of the rotary table driving sections 1a, 1b, 1c about the three axes are calculated such that the welding line 7 is nearly included in the XY plane, and the rotations of the rotary table driving sections 1a, 1b, 1c are controlled. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a welding work apparatus that assists a welding work, and more particularly to a welding work apparatus that can easily weld a joint portion between a main pipe and a branch pipe protruding from a side surface thereof.

  In recent years, automation of welding work has progressed. For example, welding of a body of an automobile or the like using an industrial robot manipulator can be mentioned. However, automation is not performed in welding of aluminum pipes used for rain gutters. Therefore, in order to improve productivity, it is desired to develop a welding apparatus that can automatically weld aluminum pipes.

  By the way, various methods such as welding, adhesion, pressure bonding, and screwing can be used for joining workpieces composed of main pipes and branch pipes such as aluminum pipes. In particular, in order to obtain an L-shaped product, a T-shaped product, a Y-shaped product, or the like by welding the tubes together, it is necessary to work by repeatedly changing the direction of the workpiece to be welded. For this reason, there has been a problem that the appearance of the appearance deteriorates due to the occurrence of discoloration caused by welding seams or welding gas.

In Patent Document 1, as a preparatory stage for welding a workpiece, first, the workpiece is placed on a rotary table, while rotating the workpiece at a constant speed, its operation is read by an image sensor and a laser displacement meter, and a welding path is calculated and measured. A welding work device that drives and controls the rotary table and the welding torch at the tip of the articulated robot based on the measurement result is disclosed.
JP 2002-103039 A

  However, since the welding work apparatus of Patent Document 1 includes two driving objects, that is, a rotary table and an articulated robot, the distribution control operation becomes complicated, and it takes time to create control data.

  In addition, since an image sensor and a laser displacement meter are used to determine the weld line, and an articulated robot is used, the welding work apparatus is expensive. Therefore, the welding work apparatus of Patent Document 1 is not suitable for the production of a large variety of small lots, and the appearance of a welding work apparatus optimal for the production of such a large variety of small lots is desired.

  In view of the above, an object of the present invention is to provide a welding work apparatus that can support welding work with a simple structure and is optimal for small-lot, multi-product production.

  In order to achieve the above object, the present invention provides an input unit for inputting welding conditions of workpieces to be welded, a Z-axis serving as a vertical axis, a Y-axis serving as a horizontal axis perpendicular to the Z-axis, and a perpendicular to the Y-axis. A three-dimensional rotary table that can rotate around three axes of the X axis and changes the posture of the workpiece, a rotary table drive unit that drives the three-dimensional rotary table, and a welding torch holding unit that holds the welding torch downward A control unit that controls the rotary base drive unit based on input information from the input unit, and the control unit is configured to coordinate all welding locations in the absolute coordinate system based on information from the input unit. When the position is calculated, the center line of the welding torch is always positioned on the XZ plane of the absolute coordinate system, and the line segment formed by the current welding location and the next welding location is the welding line, the welding line is the XY plane. Included in the predetermined tolerance width separated by a plane parallel to Calculates the three-axis rotational condition of said turntable drive unit to so that, characterized by rotation control said turntable drive unit.

  Here, the welding method is not particularly limited as long as the welding method may cause a harmful effect due to the welding arc. For example, TIG welding, plasma welding, laser welding, etc. can be illustrated, and can be applied to any of these welding methods.

  The welding conditions input to the input unit include information input directly from a computer keyboard and information input from the outside via a communication unit. For example, in the case of a T-shaped or Y-shaped joint pipe including a main pipe and a branch pipe joined to the side surface thereof, the information includes an angle and a diameter formed by the main pipe and the branch pipe. Further, the movable portion information of the three-dimensional rotary table and the movable range information of the manipulator that operates while holding the welding torch are input to the input unit. With these pieces of information, for example, the coordinates of the welding position in the absolute coordinate system of XYZ can be calculated, and the operation plan of the welding torch can be made.

  The control unit includes a CPU, ROM, and RAM of a microcomputer, and further includes other storage units. In this control unit, based on the welding conditions input from the input unit, the welding line calculation unit calculates the position information of the weld line. Further, the three-axis rotation condition of the turntable drive unit is calculated by the rotation angle calculation unit of the three-dimensional turntable. Further, the manipulator is controlled by the control calculator of the manipulator so as to hold the welding torch and move along the three axes X, Y, and Z directions orthogonal to each other.

  Note that “the weld line is included in a predetermined allowable width delimited by a plane parallel to the XY plane” means that the weld line is substantially included in the XY plane. This is to prevent the arc from hitting a portion other than the weld line by setting the welding torch and the weld line so as to be substantially included in the XY plane.

  Furthermore, by directing the welding torch downward, the shield gas spreads according to gravity, and the arc generated from the tip of the welding torch is stabilized. In addition, when the center line of the welding torch is always positioned on the XZ plane of the absolute coordinate system, and the line segment formed by the current welding location and the next welding location is the welding line, the welding line is almost in the XZ plane. Since the three-axis rotation condition of the turntable drive unit is calculated so as to be included, it is possible to easily set parameters such as the welding current while keeping the angle and direction of inclination of the welding torch with respect to the welding line constant.

  The welding torch holding part holds the welding torch downward, but the welding torch holding part may ask whether or not the welding torch can be moved along the three axes X, Y, and Z directions orthogonal to each other by a manipulator. Absent. This is because it is an essential matter of the present invention to control the three-axis rotation condition of the three-dimensional turntable so that the arc of the welding torch does not hit anything other than the welding line.

  In addition, when a line segment formed by the current welding location and the next welding location is a welding line, since the welding line is included in the XZ plane, the arc is prevented from hitting a portion other than the welding location, Loss of metallic luster such as aluminum tube can be prevented.

  Further, the Z coordinate of the next welding location is made smaller (lower) than the Z coordinate of the current welding location. Further, the center line of the welding torch is inclined at a predetermined angle with respect to the welding line in a direction opposite to the traveling direction of the welding torch within the allowable width defined by a plane parallel to the XZ plane of the absolute coordinate system XYZ. The three-axis rotation condition of the turntable drive unit is set so that welding can be performed.

  According to the said structure, since the next welding location turns downward and an arc spreads in the direction of the next welding location, the influence by the arc to the bead of the location where welding was complete | finished can be eliminated.

Further, the control unit inputs at least the following determination formulas, and calculates the three-axis rotation condition of the three-dimensional rotary table so as to satisfy these determination formulas at each welding position.
(A) | Y coordinate of the current welding location−Y coordinate of the next welding location | <L (mm) (where Y is the Y coordinate of the absolute coordinate system, L is the allowable width on both sides of the X axis)
(A) Z coordinate of the current weld location> Z coordinate of the next weld location

Furthermore, since the rotation angle of the X-axis and the Y-axis may be limited due to the mechanism of the three-dimensional rotary table, it is also possible to calculate the rotation condition by inputting these restrictions. That is, the control unit inputs the following determination formulas, and calculates the three-axis rotation condition of the three-dimensional turntable so as to satisfy these determination formulas at each welding position. However, A and B are angles when the counterclockwise rotation angle of each axis XYZ of the work coordinate system with the origin at the base center of the three-dimensional rotating table is positive and the clockwise rotation angle is negative.
(C) -A ≦ X axis rotation angle ≦ A (however, 0 ° <| A | <180 °)
(D) -B ≦ Y axis rotation angle ≦ B (however, 0 ° <| B | <90 °)

Further, the control unit can execute the operation plan according to the following procedure. That is, the control unit
1) For each welding position, while rotating the Z-axis of the three-dimensional rotary table by 360 °, it is determined whether or not the workpiece posture satisfying the determination formula can be taken at each Z-axis angle. It is divided into cases where there is no
2) When the calculation in 1) above for all welding positions is completed, the Z-axis angle that satisfies the above-mentioned determination formula while maintaining the change rate of the Z-axis angle below a predetermined value from the first welding position to the final welding position. Is selected and an operation plan for the three-axis rotation condition of the three-dimensional rotary table is performed.
3) From the first welding position to the final welding position, a Z-axis angle series that satisfies the determination formula cannot be selected, or is discontinuous, or a Z-axis angle series that satisfies the determination formula If the rate of change of the Z-axis angle exceeds a predetermined value even if the values are continuous, the allowable width L of the equation (a) is expanded and recalculated from the Z-axis angle classification of 1) above. An operation plan is performed, and the operation plan is executed so that the range of the Z axis that satisfies the determination formula is continuous with respect to movement of the welding position.

  According to the above-described configuration, the welded portion is discontinuous on the way when the operable region that satisfies all the determination formulas is continuous around the Z axis, and this is compensated for. There is a case where it passes through a conditional operable region connecting discontinuous operable regions.

  That is, the center line of the welding torch can be continuously welded in a posture inclined at a predetermined angle in the XZ plane of the absolute coordinate system in the direction opposite to the traveling direction of the welding torch. In some cases, it may pass through a conditionally operable region that proceeds slightly off the XZ plane. Even when passing through such a conditionally operable region, the welding torch moves along the welding line as much as possible, so that the influence of the arc on the metal surface can be suppressed as much as possible.

  In particular, in the welding operation of the joint pipe composed of the main pipe and the branch pipe joined to the side face, if the welding work device according to the present invention is used, automatic welding can be easily performed without requiring skill. In addition, it is an effective means for an aluminum tube in which the influence of arc on the metal surface is large.

  As described above, according to the present invention, regardless of the difference in the angle between the main pipe and the branch pipe, the diameter, or the tilt angle of the welding torch when the welding torch is tilted and applied to the welded portion of the workpiece, the T-shaped or Y-shaped Can be welded.

  In addition, by simply inputting workpiece shape data in advance, the coordinates of the welding location are calculated, and based on this, the operation plan of each part of the apparatus is automatically performed. Therefore, welding of small lots and various products can be performed efficiently. In particular, aluminum welding is a field that requires an expert, but even if there is no welding experience, a wide range of welding is possible by specifying the shape.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Configuration of welding equipment]
FIG. 1 is a block diagram showing the configuration of a welding work apparatus according to this embodiment. As shown in the figure, the welding apparatus of this embodiment includes an input unit 101 for inputting welding conditions and the like of workpieces to be welded, a Z axis that is a vertical axis, a Y axis that is a horizontal axis orthogonal to the Z axis, And a three-dimensional rotary table 1 that can rotate around three axes of the X axis orthogonal to the Y axis, and changes the posture of the workpiece 3, and rotary table driving units 1a, 1b, and 1c that drive the three-dimensional rotary table 1 A welding torch holding portion 2d that holds the welding torch 4 vertically downward, an orthogonal coordinate manipulator 2 that allows the welding torch 4 to move along the three axes X, Y, and Z directions orthogonal to each other, and the input portion And a control unit 106 that controls the movement of the turntable driving units 1a, 1b, and 1c and the welding torch 4 based on input information from 101.

  The welding conditions input to the input unit 101 include information input directly from a computer keyboard and information input from the outside via a communication unit. For example, in the case of a joint pipe such as a T-shape or a Y-shape composed of the main pipe 3a and the branch pipe 3b joined to the side surface thereof, the information includes an angle and a diameter formed by the main pipe 3a and the branch pipe 3b.

  The input unit 101 receives the movable range information of the three-dimensional rotary table 1 and the movable range information of the rectangular coordinate manipulator 2 that operates while holding the welding torch 4. With these pieces of information, for example, the coordinates of the welding location 6 in the absolute coordinate system of XYZ can be calculated, and the operation plan of the welding torch 4 can be made.

  The control unit 106 includes a CPU, ROM, and RAM of a microcomputer, and further includes other storage units. In this control unit 106, based on the welding conditions input from the input unit 101, the welding line calculation unit 106 a calculates the position information of the welding line 7. Further, the rotation angle calculation unit 106b of the three-dimensional rotation table 1 calculates the three-axis rotation conditions of the rotation table driving units 1a, 1b, and 1c.

  Further, the control operation unit 106c of the rectangular coordinate manipulator 2 performs drive control of the rectangular coordinate manipulator 2 that holds the welding torch 4 and is movable along the three axes X, Y, and Z directions orthogonal to each other.

  Further, the control unit 106 visually displays and controls a simulation for confirming the operation of the three-dimensional rotary table 1 and the operation of the rectangular coordinate manipulator 2 on the display unit 107 such as a monitor.

  The workpiece 3 to be welded is a joint pipe such as a T-shape or a Y-shape, particularly an aluminum pipe. The welded portion 6 of the aluminum pipe, that is, the joint portion between the main pipe 3a and the branch pipe 3b protruding from the side surface is automatically welded. The welding method is TIG welding, but is not limited thereto, and may be arc welding such as plasma welding or laser welding.

  As shown in FIGS. 2 and 3, the welding work device of the present embodiment includes a three-dimensional rotating table 1 and an orthogonal coordinate manipulator 2. The Cartesian coordinate manipulator 2 is installed so as to surround the upper part of the three-dimensional rotary table 1 so that welding of the welding portion 6 of the workpiece 3 can always be performed vertically downward.

  The three-dimensional turntable 1 changes the posture of the workpiece 3 to be welded so that the welding location 6 to be welded is vertically upward in order to apply the welding torch 4 to the welding location 6 of the workpiece 3. By making the welded portion 6 of the workpiece 3 vertically upward, the arc 4a generated from the welding torch 4 is equally applied to the main pipe 3a and the branch pipe 3b, which are the workpiece 3, so that the welding operation can be easily performed. Further, by changing the posture of the workpiece 3, it is possible to adjust how the arc 4a hits the workpiece 3 when welding is performed.

  As shown in FIG. 2, the three-dimensional rotary table 1 has three rotation axes (X axis, Y axis, and Z axis), and changes the posture of the workpiece 3 by the rotation of these three rotation axes. A direct drive motor is used for the Z-axis motor 1c that gives the rotation of the Z-axis of the three-dimensional turntable 1, and a stepping motor is used for the X-axis motor 1a and the Y-axis motor 1b that gives the rotation of the X-axis and the Y-axis. Has been.

  As shown in FIG. 3, the Cartesian coordinate manipulator 2 includes linear motion sliders 2a, 2b, which enable parallel movement in three directions of an X axis, a Y axis, and a Z axis for positioning the welding torch 4. 2c. Further, in order to avoid contact between the welding torch 4 and the frame of the three-dimensional rotary table 1 and the work 3, a hand link 2d having a rotary joint 2e using a stepping motor is provided at the hand portion of the orthogonal coordinate manipulator 2. Provided.

  The hand link 2d constitutes a welding torch holding part. A welding torch 4 is attached vertically downward at the tip of the hand link 2d. By attaching the welding torch 4 vertically downward, the shield gas discharged from the welding torch 4 spreads downward according to gravity, and the arc 4 a generated from the tip of the welding torch 4 can be stabilized.

  In the present embodiment, a work coordinate system is set for each of the three-dimensional rotary table 1 and the rectangular coordinate type manipulator 2 in order to plan the welding operation of the workpiece 3.

  The directions of the three axes (X axis, Y axis, Z axis) of the work coordinate system set on the three-dimensional rotating table 1 are the Z axis in the vertical direction, the Y axis in the horizontal direction perpendicular to the Z axis, and the Y axis. The direction orthogonal to the axis is taken as the X axis. That is, the three axes are in the same direction as the three rotation axes (X axis, Y axis, Z axis) of the three-dimensional rotating table 1 as shown in FIG. Note that the origin of the three axes (X axis, Y axis, Z axis) of the work coordinate system is the center of the gantry of the three-dimensional rotary table 1.

  The work coordinate system set in the rectangular coordinate manipulator 2 is a coordinate system in which the vertical direction is the Z axis, the horizontal direction is the Y axis, and the direction perpendicular to the Y axis and the Z axis is the X axis, as shown in FIG. . The origin of this coordinate system is a position where the movement distance of the linear slider 2a in the X-axis direction of the Cartesian coordinate manipulator 2 becomes 0 mm.

[Conditions for welding workpieces]
The workpiece 3 is welded using TIG welding. In TIG welding, welding is performed by filling a melted welded portion 6 with a rod made of substantially the same material as the workpiece 3 called a filler wire 9. As a result of welding, a scale-like weld metal called a bead 4 b is formed on the weld line 7. In the welding operation, as a standard for a product having high quality, the width and height of the bead 4b are uniform and the bead 4b does not lose its metallic luster. Further, the welded portion 6 of the workpiece 3 forms a line so as to surround the periphery of the workpiece 3. This line is referred to as a weld line 7.

  In this embodiment, in the formation of the bead 4b obtained as a result of welding, in particular, the influence on the surface of the work 3 due to the melting action of the arc 4a is minimized, and the bead 4b without loss of metallic luster can be formed. The posture of the workpiece 3 is changed in consideration of the posture of the welding torch 4 and the range hit by the arc 4a.

  As shown in FIG. 4, the rotation direction of each axis of the three-dimensional rotating table 1 is counterclockwise when the three-dimensional rotating table 1 is viewed from the positive direction of each axis of the working coordinates with the center of the gantry 1e as the origin. A clockwise rotation is a positive direction, and a clockwise rotation is a negative direction.

  As shown in FIG. 4, the three-dimensional rotary table 1 used in the present embodiment is limited in the movable range of the rotary shaft that realizes the rotation of the X axis and the Y axis due to its mechanism. The X axis of the three-dimensional turntable 1 can be rotated up to 120 ° in both positive and negative directions. The limitation on the movable range of the X axis is to prevent the branch pipe 3b from coming into contact with the frame of the three-dimensional turntable 1 when the workpiece 3 is rotated.

  The range in which the Y axis can rotate is 45 ° in the positive direction and 60 ° in the negative direction. This limitation is a limitation on the mechanism of the three-dimensional rotary table 1 designed from the posture when the operator applies the welding torch 4 to the welding portion 6 of the workpiece 3 when the workpiece 3 is welded manually. . Note that the rotation of the Z axis of the three-dimensional turntable 1 has no limitation on the rotation angle. Therefore, the Z-axis of the three-dimensional turntable 1 can freely rotate 360 ° in both the positive direction and the negative direction.

Due to the limitation of the movable range of the three-dimensional rotary table 1 mentioned above, in the welding operation plan performed in this embodiment, the following conditional expressions are set in order to operate the three-dimensional rotary table 1 within the movable range. .
−120 ° ≦ Rotation angle of X axis ≦ 120 ° (C)
−60 ° ≦ Y-axis rotation angle ≦ 45 ° (D)

  The limitation on the rotation angle of the X axis and the Y axis is not limited to the above example. For example, the rotation angle of the X-axis can be within a range of 180 degrees when the mechanism of the three-dimensional turntable is ideal. Similarly, the rotation angle of the Y axis can be set within a range of 90 °.

  Next, the movable range of the rectangular coordinate manipulator 2 will be described.

  As shown in FIG. 3, the rectangular coordinate manipulator 2 can position the welding torch 4 with the three linear sliders 2a, 2b, and 2c. These are all realized by using the same linear slider having a movable range of 400 (mm). Therefore, the movable range of the parallel movement of the rectangular coordinate manipulator 2 is 400 (mm) in the X-axis, Y-axis, and Z-axis directions.

  As shown in FIG. 5, the rotation movable range of the rotary joint 2e provided on the hand link 2d is limited to 90 ° in both positive and negative directions when viewed from the Z-axis direction of the absolute coordinate system. This is to prevent the welding torch 4 attached to the hand link 2d from coming into contact with the frame of the Cartesian coordinate manipulator 2.

From the above, in order to operate the rectangular coordinate manipulator 2 within the movable range, the following conditional expressions were set.
0 (mm) ≦ travel distance of linear slider ≦ 400 (mm) (3)
−90 ° ≦ Rotation angle of rotating joint ≦ 90 ° (4)

[Reproduction of welding situation in aluminum plate automatic welding experiment]
FIG. 6 is a perspective view schematically showing the state of the automatic welding experiment of the aluminum flat plate 5. In this automatic welding experiment, the welding torch 4 is inclined and applied to the welded portion 8 of the aluminum flat plate 5, and the aluminum flat plate 5 to be welded is moved while keeping the inclination angle of the welding torch 4 constant. Weld. In this welding, it is prevented that the metallic luster of the surface of the aluminum flat plate 5 is lost due to the arc 4a hitting the surface of the aluminum flat plate 5. As a method for that purpose, the welding torch 4 is inclined and applied to the welded portion 8 of the aluminum flat plate 5 to be welded.

  For example, when the welding torch 4 is applied to the welding location 8 from directly above, the arc 4a hits the location where welding has been completed. Therefore, by tilting the welding torch 4 in the direction opposite to the traveling direction of the welding torch 4, it is possible to prevent the arc 4a from hitting the place where welding has been completed. Moreover, the direction to which the front-end | tip of the welding torch 4 faces can be fixed, and it can also prevent the arc 4a from hitting parts other than the welding location of the aluminum flat plate 5. FIG. Since the tip of the inclined welding torch 4 is always in the direction of the next welding spot 8a, the arc 4a always spreads on the welding line 8a. Thereby, the influence by the melt | dissolution effect | action of the arc 4a to the surface of the aluminum flat plate 5 other than a welding location can be prevented.

  In this embodiment, similarly to the situation of the automatic welding experiment of the aluminum flat plate 5, it is ensured that the arc 4a does not hit the place where the welding is completed, and the arc 4a does not hit the surface of the work 3 other than the welded place. To. Therefore, in this embodiment, the welding torch 4 is tilted with respect to the welding location 6, and further, the direction in which the arc 4a spreads is fixed to prevent it from hitting a location other than the welding location. This is because it is considered that a bead 4b having no loss of metallic luster can be obtained even by automatic welding of the workpiece 3.

  First, it will be described that the welding torch 4 is inclined and applied to the welding location 6.

  In the present embodiment, a direction vector representing a direction for applying the welding torch 4 to the welding location 6 of the workpiece 3 is used. FIG. 7 shows how to obtain the direction vector R.

In welding portion 6 of the workpiece 3, determined the normal H _e normal H _s and the branch pipe 3b of the main 3a, vectors able by taking the two normals of the bisector is the direction vector R . This direction vector R is a direction vector planned to apply the welding torch 4 to the welded portion 6 of the workpiece 3 from directly above.

  The situation in which the orientation of the workpiece 3 is changed by the three-dimensional rotary table 1 so that the direction vector R is vertically upward, and the welding torch 4 is applied from the vertically upward to the welding location 6 by the operation of the orthogonal coordinate manipulator 2 is as follows. In the welding experiment of the aluminum flat plate 5, the arc 4 a hits the welded spot 6 in the same manner as when the welding torch 4 is applied to the welded spot 8 from directly above. Therefore, the influence of the melting action of the arc 4a and the cleaning action of the shield gas reaches the welded portion 6 where the welding is finished. For this reason, the welded portion 6 that has been welded is melted again, and the metallic luster of the bead 4b is lost.

  In the present embodiment, the direction vector R set at the welding location 6 of the workpiece 3 is further tilted at an angle φ with respect to the Z axis of the absolute coordinate system shown in FIG. As a result, the direction vector R and the Z axis of the absolute coordinate system form an angle φ (see FIG. 9). The welding torch 4 is applied from the positive direction of the Z axis. Therefore, the angle φ is an angle at which the welding torch 4 is inclined when the welding torch 4 is applied to the welding portion 6 of the workpiece 3.

  Next, a method for setting the direction in which the arc 4a spreads on the weld line 7 of the workpiece 3 will be described. When the welding torch 4 is tilted and applied to the welded portion 6 of the workpiece 3 as in the situation of the automatic welding experiment of the aluminum flat plate 5 shown in FIG. 6, depending on the angle formed by the center line of the welding torch 4 and the welding line 7, The direction in which the arc 4a spreads changes.

  FIG. 10 shows a change in the angle formed by the center line of the welding torch 4 and the welding line 7 of the workpiece 3 on the XY plane of the absolute coordinate system. Here, a region where the arc 4a spreads is indicated by a hatched portion. As shown in FIG. 10 (a), when the center line of the welding torch 4 and the weld line 7 of the workpiece 3 form an angle of 90 °, the shaded portion where the arc 4a spreads is the area of the workpiece 3 other than the welded portion. It spreads to the surface. Therefore, when the arc 4a hits, the surface of the work 3 other than the welded portion is melted and loses its metallic luster, so that the quality of the work 3 is deteriorated.

  As shown in FIG. 10B, when the angle formed by the center line of the welding torch 4 and the welding line 7 of the workpiece 3 is 0 °, the center line of the welding torch 4 is along the welding line 7 of the workpiece 3. It becomes the state. In this case, since the arc 4a spreads on the weld line 7 of the workpiece 3, the range in which the arc 4a hits a place other than the weld line can be minimized.

  In the present embodiment, as shown in FIG. 10B, the center line of the welding torch 4 is set along the weld line 7 of the workpiece 3. Since the welding line 7 of the workpiece 3 is a curve, the automatic welding experiment of the aluminum flat plate 5 is performed by setting the center line of the welding torch 4 along the line connecting the current welding point 6 and the next welding point 6a. Can create a similar state.

  Further, since the welding torch 4 is vertically downward, it is considered that the center line of the welding torch 4 is always on the XZ plane of the absolute coordinate system. Therefore, the direction vector R is tilted in the XZ plane, and the angle at which the welding torch 4 is tilted is configured in the XZ plane.

Furthermore, in the present embodiment, the line segment formed by the current welding location 6 and the next welding location 6a is considered as the welding line 7, and θ _{R is} rotated around the direction vector R set in the welding location 6 of the workpiece 3 to rotate the workpiece 3 By changing the posture, the weld line 7 is included in the XZ plane (see FIG. 9B). As a result, the angle formed by the center line of the welding torch 4 and the welding line 7 is φ. That is, by rotating the workpiece 3 with the direction vector R shown in FIG. 9B as the rotation axis, the welding torch 4 and the welding line 7 form an angle φ in the XZ plane.

From the above, in the present embodiment, the following conditional expression is set using the coordinates of the current welding location 6 and the coordinates of the next welding location 6a. From this conditional expression, it is determined that the direction in which the arc 4a spreads is on the weld line 7. Note that L in this conditional expression is an allowable width in the direction in which the arc 4a spreads.
| Y-coordinate of current welding location-Y-coordinate of next welding location | <L (mm) (A)

  When this condition is satisfied, it is determined that the arc 4a hits other than the welded portion and minimizes the influence on the surface of the workpiece 3 (see FIG. 11). By giving an allowable width to the conditional expression, a width of L (mm) is given to both sides of the X-axis, and the welding line 7 connecting the current welding location 6 and the next welding location 6a becomes the circumference L ( mm), the conditional expression is satisfied.

  In addition, when the welding torch 4 is applied to the welded portion 6 of the workpiece 3, the direction in which the welding torch 4 tilts varies depending on the direction in which the welding line 7 of the workpiece 3 tilts. The change in the direction in which the welding torch 4 tilts is shown in FIG.

  FIG. 12 shows the welding line 7 connecting the current welding location 6 and the next welding location 6a, as viewed from the positive direction of the Y axis on the XZ plane of the absolute coordinate system where the welding torch 4 is present. Here, the advancing direction of the welding torch 4 is a positive direction of the X axis in the absolute coordinate system, and the advancing direction of the welding torch 4 is indicated by an arrow at the top in FIG. As shown in FIG. 12A, when the Z coordinate of the next welding location 6 a is larger than the Z coordinate of the current welding location 6, the welding torch 4 is the positive direction of the X axis that is the traveling direction of the welding torch 4. Will lean on. In this case, the arc 4a generated from the welding torch 4 spreads in the direction opposite to the next welding location 6a, that is, in the direction of the welding location 6 where welding has been completed. Therefore, the bead 4b at the place where the welding is finished is melted by the melting action of the arc 4a, and the metallic luster is lost from the bead 4b.

  12B, when the Z coordinate of the next welding location 6a is smaller than the Z coordinate of the current welding location 6, the welding torch 4 is opposite to the traveling direction of the welding torch 4. It will tilt in the negative direction of the axis. In this case, since the arc 4a generated from the welding torch 4 spreads in the direction of the next welding location 6a, the influence of the arc 4a on the bead 4b at the location where welding has been completed can be prevented.

Therefore, in this embodiment, by changing the posture of the workpiece 3, the posture of the workpiece 3 is changed so that the welding torch 4 is inclined in the direction of travel, that is, the direction opposite to the direction in which the next welding location 6a is present. By changing the posture of the workpiece 3 and tilting the welding line 7 so as to be in such a state, the Z coordinate of the next welding location 6 a is made lower than the Z coordinate of the current welding location 6. Therefore, in the present embodiment, the following conditional expression is set in order to determine the tilt direction of the work 3 for tilting the welding torch 4.
Z coordinate of the current welding location> Z coordinate of the next welding location ...

[Calculation method of workpiece welding point coordinates and rotation angle of 3D turntable]
As described above, in the operation plan performed in the present embodiment, the validity of the operation is determined based on the coordinates of the current welding location 6 after changing the posture of the workpiece 3 and the coordinates of the next welding location 6a. Therefore, it is necessary to obtain the coordinates of the welded portion 6 of the workpiece 3 during the operation plan.

  In addition, since the welding torch 4 is always inclined and applied to the welded portion 6 of the workpiece 3, the direction vector set to the welded portion 6 of the workpiece 3 is always within the Z axis and XZ plane of the absolute coordinate system during the welding operation. The angle φ must be maintained. Therefore, a method for calculating the coordinates of the welded part 6 of the workpiece 3 used for determining the conditional expression and a method for calculating the rotation angle of the three axes of the three-dimensional rotary table 1 when changing the posture of the workpiece 3 will be described.

[Calculation method of the coordinates of the welded part of the workpiece]
The weld line 7 of the workpiece 3 exists so as to surround the workpiece 3, but the welded portion 6 of the workpiece 3 exists particularly on the circumference of the branch pipe 3b. From this, in this embodiment, the coordinate of the welding location 6 was calculated | required by taking the reference point 6b for calculating | requiring the coordinate of the welding location 6 on the branch pipe 3b.

  First, the coordinates of the welding location 6 of the workpiece 3 are obtained on the work coordinate system set for the workpiece 3 shown in FIG. This work coordinate system has an origin at the intersection of the center line of the main pipe 3a of the work 3 and the center line of the branch pipe 3b. Further, the center line of the main pipe 3a of the work 3 and the X axis coincide with each other, and the direction in which the branch pipe 3b is inclined is defined as a positive direction.

  The Y axis is a positive direction in the side surface direction of the workpiece 3. Further, the Z-axis is set so that the center line of the branch pipe 3b is located in the XZ plane, and the Z-axis is a positive direction in the direction in which the branch pipe 3b extends. Due to the T-shaped or Y-shaped shape of the work 3, the center line of the main pipe 3a and the center line of the branch pipe 3b form an angle. Therefore, the welding location 6 is considered to exist with the intersection of the center lines as the origin, and the origin of the work coordinate system is the intersection of the center line of the main pipe 3a and the center line of the branch pipe 3b.

  FIG. 13 shows a reference point 6 b set for coordinate calculation of the welded portion 6 simultaneously with the work coordinate system set for the workpiece 3. The reference point for obtaining the coordinates of the welded part 6 of the workpiece 3 is assumed to be located on the circumference of the tip of the branch pipe 3b as shown in FIG. When a straight line along the surface of the branch pipe 3b is drawn from the reference point set on the branch pipe 3b, the straight line always intersects the main pipe 3a.

  In the calculation of the coordinates of the welded part 6 of the workpiece 3 in this embodiment, the center line of the main pipe 3a and the center line of the branch pipe 3b form an angle, and the reference point 6b and the welded part 6 are parallel to the center line of the branch pipe 3b. The coordinates of the welded part 6 were obtained from the three conditions that it can be connected with a straight line and that the welded part always exists on the main pipe 3a and the branch pipe 3b at the same time.

  The workpiece 3 includes a T-shaped type and a Y-shaped type, and the angle formed by the center line of the main pipe 3a and the branch pipe 3b is formed by the X axis of the work coordinate system of the work 3 and the center line of the branch pipe 3b. The angle is 91.1 ° for the T-shape and 45 ° and 75 ° for the Y-shape.

Here, the coordinates of the welding point 6 of the workpiece 3 are (X, Y, Z), and the coordinates of the reference point 6b for obtaining the coordinates of the welding point 6 taken at the tip of the branch pipe 3b are (x _e , y _e , z _e ).

First, consider a state where the branch pipe 3b overlaps the main pipe 3a, that is, a state where the angle between the center line of the main pipe 3a and the center line of the branch pipe 3b is 0 ° (see FIG. 14A). In this state, taking a point on the circumference of the branch pipe 3b tip, the length of the branch pipe 3b to l _e, the radius of the branch pipe 3b and r _e. Further, since a point on the circumference of the branch pipe 3b, the work coordinate system shown in FIG. 14 (b) to use of an angle theta _e shown _{B (x b, y b,} z b) the work 3 coordinates This is expressed as follows.
x _b = l _e (7)
y _b = r _e cos θ _e (8)
z _b = r _e sin θ _e (9)

In fact, the center line of the center line and the branch pipe 3b of the main 3a is because an angle theta _a, the coordinates of the reference point is obtained by rotating the point B in the Y-axis of the work coordinate system of the workpiece 3. Therefore, the coordinates of the reference point are
x _b = x _b cos θ _a + z _b sin θ _a (10)
y _b = y _b (11)
z _b = −x _b sin θ _a + z _b cos θ _a (12)
It becomes. Here, the angle θ _e representing the point on the circumference of the used branch pipe 3b represents the position of the reference point 6b on the circumference of the branch pipe 3b. Therefore, the angle theta _e it is possible to identify the position of the welding portion (6) located on the circumference of the branch pipe 3b, it is possible to determine the positions of all the welding points 6 by changing the angle.

Next, the coordinates of the welding location 6 of the workpiece 3 are obtained from the coordinates of the reference point 6b. First, since the center line of the branch pipe 3b of the main 3a of the workpiece 3 is an angle, it is possible to obtain the angle of the center line and a theta _a following equation.
(X−x _e ) tan θ _a = Z−z _e (13)

Moreover, since the welding location 6 and the reference point 6b of the workpiece 3 can be connected with a straight line on the surface of the branch pipe 3b, the following equation can be obtained.
Y = y _e (14)

In addition, if the diameter of the main pipe 3a is r, the welded portion 6 of the work 3 is always on the main pipe 3a, and therefore the following equation can be obtained.
Z ² + Y ² = r ² (15)

By solving the above equations (13), (14), and (15), the coordinates (X, Y, Z) of the welding location 6 on the work coordinate system set for the workpiece 3 are expressed as follows. The

Here, two values having different signs are obtained for the Z coordinate of the welded portion 6. However, since the weld location 6 exists only in the upper half of the main pipe 3a, a positive value may be selected as the value of the Z coordinate.

[Calculation method of rotation angle of 3D turntable]
Next, a method for calculating the rotation angle of the three-dimensional turntable 1 will be described.

  The inclination of the welding torch 4 with respect to the welding location 6 of the workpiece 3 is created by inclining the direction vector R set at the welding location 6 by an angle φ in the XZ plane with respect to the Z axis of the absolute coordinate system. First, the coordinates of the welded part 6 of the workpiece 3 are obtained using the calculation method described above. Since the workpiece 3 is attached to the three-dimensional turntable 1, it is represented on an absolute coordinate system in which the coordinates of the obtained welding location 6 are set.

In the present embodiment, the direction vector R set at the welding point 6 of the workpiece 3 is set to the three-axis rotation angle of the three-dimensional rotary table 1 for matching the target vector _Ra, and the angle for changing the posture of the workpiece 3. It was.

  The three-dimensional turntable 1 used in the present embodiment includes a mechanism as shown in FIG. Therefore, the orientation vector R uses the X-axis and Y-axis rotations of the three-dimensional turntable 1 to change the posture of the workpiece 3 so that the workpiece 3 moves to the target vector position even if the Z-axis rotation is applied. (See FIG. 15B).

When the posture of the workpiece 3 is changed by rotation θ _R around the direction vector R for moving the weld line 7 of the workpiece 3 to the XZ plane, and the influence of the arc 4a on the surface of the workpiece 3 is minimized, the direction vector The rotation angle around R can be expressed as the rotation angle of the Z axis of the three-dimensional rotating table 1. Therefore, the rotation angle of the Z-axis of the three-dimensional turntable 1 When phi _z,
φ _z = φ _R (19)
Can be expressed as

  Further, when the posture of the workpiece 3 is changed by the rotation of the three axes, the orientation of the direction vector R can be changed by the rotation of the X axis and the Y axis of the three-dimensional rotary table 1, so that the posture of the workpiece 3 is unified. In order to make a determination, it is necessary to determine the rotation of the Z-axis of the three-dimensional turntable 1 in advance.

When the posture of the workpiece 3 is changed, the target vector R _a (x _a , y _a , z _a ) forms an angle φ with the Z axis of the absolute coordinate system, and the angle φ is configured in the XZ plane of the absolute coordinate system. Therefore, R _a can be expressed as follows.
(X _a , Y _a , Z _a ) = (sin φ, 0, cos φ) (20)

The direction vector R (x _r , y _r , z _r ) set for the welded part 6 is the coordinate of the welded part 6 of the workpiece 3 expressed on the absolute coordinate system (X, Y, Z) and the direction vector R Is obtained from the vertex T (x _t , y _t , z _t ) as follows.
_{x r = x t -X ··· (} 21)
y _r = y _t −Y (22)
_{z r = z t -Z ··· (} 23)

Next, determine the three-dimensional rotation angle of the turntable 1 for moving the direction vector R to the position of the target vector R _a. Here, the rotation angle of the X-axis of the absolute coordinate system phi _x, when the rotation angle of the Y-axis and phi _y, X-axis, Y-axis, the rotation matrix according to the Z axis _R φz, R φy, R φR is less, respectively It is expressed as

Using these three rotation matrix, since the matching the direction vector R to the target vector R _a, can be obtained the following equation.
_{R a = R φx R φy R} φR R ··· (27)

By expanding this equation, the following three equations can be obtained. Here, a sin [theta _{x S} x, described for short cos [theta] _x and _{C x.} Similarly, the sine and cosine of θ _y and θ _R are also abbreviated.

When these three equations are solved for θ _x and θ _y , the rotation angles of the X axis and the Y axis of the three-dimensional rotary table 1 when changing the posture of the workpiece 3 can be obtained as follows.

  The X-axis rotation angle and the Y-axis rotation angle obtained by the equations (31) and (32) can be obtained in two values according to the sign of ±, but are included in the movable range of the three-dimensional turntable 1. Select the angle so that it takes a value.

[Operation planning method]
Next, in the motion planning method proposed in the present embodiment, the motion planning method of the three-dimensional rotary table 1 for changing the posture of the workpiece 3 and the Cartesian coordinate manipulator 2 for determining the position of the welding torch 4 The motion planning method will be described.

In the operation planning method proposed in this embodiment, the welding operation of the workpiece 3 is planned in the order shown below.
(1) Plan of three-axis rotation angle of the three-dimensional turntable 1 for determining the posture of the workpiece 3 (2) Cartesian coordinate shape for applying a torch to the welded portion 6 of the workpiece 3 whose posture has been changed Planning of parallel movement distance of three linear sliders of manipulator 2 and rotation angle of hand link 2d

[Operation plan of 3D turntable]
The calculation method for determining the angle between the X axis and the Y axis by using the angle of the Z axis of the three-dimensional rotating table 1 as a variable has been described. This method is a calculation method for always applying the welding torch 4 to the welded portion 6 of the workpiece 3 with an angle φ (see FIG. 9).

  Therefore, in this embodiment, in order to determine the rotation angles of the X axis and the Y axis of the three-dimensional rotating table 1 from the equations (32) and (33), first, the angle of the Z axis of the three-dimensional rotating table 1 is determined. Must. Thereafter, the coordinates of the welded part 6 are obtained by coordinate transformation, thereby determining the expressions (a) and (b). In the present embodiment, the operation plan of the three-dimensional rotary table 1 is performed by the procedure shown in FIG.

[Method for selecting the posture of a workpiece that satisfies the conditions for motion planning]
The posture of the work 3 in this embodiment is determined by determining the value of the Z-axis angle of the three-dimensional turntable 1 from the calculation method of the X-axis and Y-axis rotation angles of the three-dimensional turntable 1 described above. Can be sought.

  Further, in the operation planning method performed this time, the welding torch 4 shown in the equations (a) and (b) is changed to the welding point 6 by obtaining the coordinates of the welding point 6 by coordinate conversion from the rotation angle of the three-dimensional rotating table 1. A judgment formula for tilting and a judgment formula for suppressing the influence of the welding arc 4a on the surface of the frame can be determined.

  Similarly, the determination formula for the movable range of the three-dimensional rotary table 1 shown in the equations (c) and (d) can also be determined.

  Therefore, in order to determine the determination formulas for all conditions, the angle of the Z axis of the three-dimensional rotary table 1 must be determined. Therefore, in the operation plan performed in the present embodiment, first, at all rotation angles that can be taken by the Z axis of the three-dimensional rotary table 1, the determinations shown in the equations (a), (b), (c), and (d) are given. Whether or not the equation is satisfied is determined at each welding point 6 of the workpiece 3, and the posture of the workpiece 3 that satisfies all the determination equations and the posture of the workpiece 3 that does not satisfy even one of the determination equations are classified. The result was expressed as image data on a two-dimensional plane using pgm (portable gray map) format data.

  In the image data in the pgm format, one number is recognized as a color of one pixel, and is displayed as an image by being read by software capable of processing an image such as GIMP (GNU Image Manipulation Program). Since the image has a gray scale, in the present embodiment, the maximum value of the number is set to 8, and when the number is 8, it is set to white, and when it is 0, it is set to black. In the present embodiment, even if there is even one judgment formula, the numerical value of the region 10 indicating the posture of the workpiece 3 that satisfies all the judgment formulas shown in the formulas (a), (b), (c), and (d) is set to 7. The numerical value of the area 11 indicating the posture of the workpiece 3 that is not satisfied is represented by 8 as white.

In the present embodiment, by changing used in a method for obtaining a reference point 6b on the branch pipe 3b described above, the angle theta _e to represent a point on the circumference of the branch pipe 3b by once welding of the workpiece 3 The number of locations 6 was 360. Moreover, the angle of the Z-axis which can be taken in each welding location 6 of the workpiece | work 3 was 0-359 degrees.

  Therefore, this time, 360 welding positions 6 and 360 postures of the work 3 at each welding position 6, a 360 pixel × 360 pixel pgm image was created. Based on this pgm image, 360 different postures of the workpiece 3 are created for each welding point 6, and the posture of the workpiece 3 is classified into the posture of the workpiece 3 that satisfies all the judgment formulas and the posture of the workpiece 3 that is not so. The result was confirmed.

  In the pgm image shown in FIG. 17, a region indicating the posture of the workpiece 3 that satisfies all the determination formulas is represented in light gray. Moreover, the area | region which shows the attitude | position of the workpiece | work 3 when one determination formula is not satisfy | filled is represented in white. The vertical axis of the created pgm image is from the number 1 to 360 of the welding points 6 in the direction from the upper end to the lower end, and the horizontal axis is the angle 0 to the Z axis of the three-dimensional rotary table 1 from the left end to the right end. It represents up to 359 °.

  Here, the shape of the workpiece 3 in FIG. 17 shown as an example is a T-shaped image having a different diameter when the diameter of the main pipe 3a is 89 (mm) and the diameter of the branch pipe 3b is 63 (mm). Further, the angle at which the welding torch 4 tilts when the welding torch 4 is applied to the welded portion 6 of the workpiece 3 is 20 °, and the value of the allowable width L in the equation (a) is 0.05 (mm).

  In the present embodiment, a light gray area indicating the posture of the workpiece 3 when all of the above-described determination expressions (a), (b), (c), and (e) are satisfied is referred to as an operable area 10. . In addition, a white area indicating the posture of the work 3 when at least one determination formula is not satisfied is referred to as an inoperable area 11. In addition, as shown in the above description of the movable range of the three-dimensional rotating table 1, the Z-axis of the three-dimensional rotating table 1 can be freely rotated 360 °. Therefore, in the motion planning method performed in the present embodiment, the right end and the left end of all created pgm images are considered to be continuous.

  In order to continuously weld all the welding locations 6 of the workpiece 3, it is desirable that the operable region 10 appearing in the pgm image exists continuously from the upper end to the lower end. In the pgm image of FIG. 17 shown as an example, the right end and the left end of the pgm image are continuous as the Z-axis angle, and therefore it can be said that the operable region 10 is continuous. However, as can be seen from the pgm image shown in FIG. 17, the operable area 10 has a width. Therefore, one Z-axis angle must be determined from this width.

  Therefore, in this embodiment, the maximum value and the minimum value of the Z-axis angle of the three-dimensional turntable 1 that constitutes the operable region 10 of each welding location are examined, and the Z-axis angle is determined by taking the midpoint thereof. I decided on one. FIG. 18 is a pgm image obtained by adding a line 12 representing the Z-axis angle of the three-dimensional rotary table 1 determined by this method to FIG. In this image, it can be confirmed that the line 12 indicating the determined Z-axis angle of the three-dimensional rotating table 1 passes through the center of the width of the light gray portion representing the operable region 10.

[Situation where the operable area becomes discontinuous]
In the pgm image (see FIG. 17) in the case of the workpiece 3 having a different diameter T shape, the operable region 10 is continuous from the upper end to the lower end. This is because the weld line 7 in the case of the different diameter T-shape is circular along the circumference of the branch pipe 3b. However, in the case of the same diameter pipe, as shown in FIG. 19, the weld line 7 is refracted by 90 ° on the side surface. In such a case, when the welding torch 4 is applied to the welding point 6 where the welding line 7 is refracted, the next welding point 6 is located at a different position in the 90 ° direction with respect to the welding line 7 that has been welded until then. Will be the position. Therefore, when the operation plan is performed so that the coordinates of the current welding location 6 and the next welding location 6a satisfy the formula (A), the position of the next welding location 6a is positioned on the XZ plane. In this case, the angle of the Z axis of the three-dimensional rotary table 1 must be rotated by 90 ° at the location where the weld line 7 is refracted.

  Moreover, since the angle of the Z axis of the three-dimensional rotating table 1 is greatly changed, the rotation angles of the X axis and the Y axis are also greatly changed. Therefore, in the work 3 having the same diameter where the welding line 7 is refracted, the operable region 10 exists in all the welding locations 6, but the operable region 10 is in a state of being divided in the middle. Further, even if the Z axis of the three-dimensional rotary table 1 is determined within the operable region 10, the line representing the determined Z axis angle becomes discontinuous on the way (see FIG. 20).

  In addition, even if the posture of the workpiece 3 is changed within the movable range of the three-dimensional turntable 1 in a state where the expressions (C) and (D) are satisfied, the expressions (A) and (B) may not be satisfied. Conceivable. In such a case, there is a range in which the operable region 10 does not exist at the welding location 6 (see FIG. 21). Therefore, even when there is a welded portion 6 that does not have the operable region 10, the operable region 10 is discontinuous, and the line representing the determined Z-axis angle is also discontinuous.

  From the above, in order to perform the welding operation plan of the workpiece 3, the pgm is such that the operable region 10 exists continuously from the upper end to the lower end and can exist continuously as a line representing the determined Z-axis angle. You must create an image. Therefore, in the present embodiment, a pgm image in which the allowable width L in the expression (a) is changed is created.

  FIG. 22 shows pgm images of the T-shaped workpiece 3 having the same diameter 140 (mm) when the allowable width L of the formula (a) is 0.05 (mm) and 1.5 (mm). It is. In FIG. 22A, the operable region 10 is discontinuous and cannot be drawn so that the line 12 representing the determined Z-axis angle is continuous, but in FIG. 22B, the allowable width L is increased. Since the posture of the workpiece 3 satisfying the expression (a) is increased by the above, the operable region 10 exists continuously, and the determined Z-axis angle line 12 can be drawn.

  However, widening the allowable width L in the equation (a) means that in the welding operation plan of the workpiece 3, the influence on the surface of the workpiece 3 due to the melting action of the arc 4a is increased. Therefore, in this embodiment, in order to minimize the influence on the surface of the work 3 due to the melting action of the arc 4a, an image obtained by superimposing two pgm images having different allowable widths L in the formula (a) (see FIG. 23). )created.

  Since this pgm image has three different areas, it is divided into three colors. The first is a light gray area representing an area that becomes the operable area 10 in both the images of FIGS. The second is a dark gray area that becomes the operable area 10 only in the image of FIG. 22B in which the value of the allowable width L is increased. The third is a white region that becomes the inoperable region 11 in both the images of FIGS. 22 (a) and 22 (b). In the present embodiment, a region expressed in light gray is also referred to as an operable region 10 and a region expressed in white is referred to as an inoperable region 11 in an image obtained by superimposing two pgm images. A region expressed in dark gray is referred to as a conditionally operable region 10a.

  In the present embodiment, first, the angle of the Z axis of the three-dimensional turntable 1 is determined within the operable region 10, and the three-dimensional state within the conditional operable region 10 a is determined only where the operable region 10 is discontinuous. The angle of the Z axis of the turntable 1 is determined. By this method, the influence on the surface of the workpiece 3 due to the melting action of the arc 4a can be suppressed as much as possible.

[Method of determining the angle of the 3D turntable when the operable area becomes discontinuous]
Next, when the allowable width L of the formula (a) is a small value, the welding line 7 of the workpiece 3 is refracted, and the operable region 10 does not exist depending on the operating range of the three-dimensional rotary table 1. A method for planning the angle of the Z axis of the three-dimensional rotary table 1 when the possible region 10 is discontinuous will be described.

  When the operable region 10 of the pgm image is discontinuous, in the present embodiment, the angle of the Z axis of the three-dimensional rotary table 1 is determined from the conditional operable region 10a. As the determination method, a straight line connecting the operable region 10 through the conditional operable region 10a was drawn, and the Z-axis angle was determined along the straight line.

  In order to draw a straight line, first, the created pgm image is considered as a two-dimensional coordinate system as shown in FIG. In this two-dimensional coordinate system, the X axis represents the angle of the Z axis of the three-dimensional rotating table 1, and the Y axis represents the position of the welded portion of the workpiece 3. The straight line 13 for determining the angle of the Z axis of the three-dimensional rotating table 1 can be represented as a straight line of a linear function in this two-dimensional coordinate system.

  In the present embodiment, in order to draw the straight line 13, the slope value of the straight line 13 and the passing point of the straight line 13 are determined on the two-dimensional coordinate system. The value of the inclination of the straight line 13 determines the amount of change in the Z-axis angle when the welding location 6 moves by one point when the Z-axis angle is determined along the straight line 13.

In the present embodiment, the moving time when moving the welding spot 6 is set to 1.0 (s), the operating speed of the three-dimensional rotating table 1 is set to 2.0 (° / s), and the angle obtained from these conditions The maximum value of the amount of change was 2.0 °. Therefore, in this embodiment, the inclination of the straight line 13 is set to 0.5 so that the amount of change in angle is 2.0 °. Further, by determining the passing point of the straight line 13, the position of the straight line 13 on the two-dimensional coordinate system is determined. Hereinafter, a point through which the drawn straight line 13 always passes is referred to as a reference point 13c for drawing the straight line 13, and the coordinates on the two-dimensional coordinate system are (X _P , Y _P ).

  The Z-axis of the three-dimensional turntable 1 can be freely rotated 360 °. Therefore, in the case of a pgm image as shown in FIG. 23, the straight line for determining the angle of the Z axis of the three-dimensional rotating table 1 can be operated in two ways via the portion where the angle of the Z axis is 0 °. The regions 10 are connected (see FIG. 25).

  In addition, as shown in FIG. 26, when the operable region 10 is divided by the inoperable region 11, it is necessary to connect the two operable regions 10 so as to avoid the inoperable region 11. FIG. 27 is a flowchart showing a procedure for drawing a straight line 13 for determining the angle of the Z axis of the three-dimensional rotary table 1.

  From here, the method for drawing the straight line 13 will be described in accordance with the procedure shown in FIG. First, a method for determining the position of the reference point 13c of the straight line 13 will be described.

When connecting the operable region 10 angle of Z-axis via the position of 0 ° in a straight line 13 (see FIG. 25), the X-coordinate X _P of the reference point 13c of the straight line 13 and 0. However, as shown in FIG. 28, there is a width of the dark conditionable operable region 10a on the straight line 13 indicating the position where the Z-axis angle is 0 °. Therefore, there are a plurality of Y-coordinate values Y _P when the reference point is (0, Y _P ). Therefore, in order to determine the reference point 13c to draw a straight line 13 at one point has to determine the Y _P.

In the present embodiment, it was determined by subtracting two more straight lines 13a to _{Y P,} the 13b (see FIG. 29). As shown in FIG. 29, the two straight lines 13a and 13b used here draw points 13d and 13e located at the boundary between the inoperable region 11 and the conditional operable region 10a as passing points. In these two straight lines 13a and 13b, when the X coordinate is set to 0 ° and the Y coordinate is obtained, the width of the two Y coordinates is the straight line 13 for determining the Z-axis angle within the inoperable region 11. This represents the width of the Y coordinate that can be drawn without passing. Thus, these two lines 13a, the midpoint of the value of Y coordinate for _X P = 0 on 13b, and the value of _{Y P} (see FIG. 30).

In addition, when the operable region 10 does not exist as shown in FIG. 26, the angle of the Z axis is determined along the straight line 13. The straight line is drawn by determining the reference point 13c (X _P , Y _P ) on the two-dimensional coordinate system. First, to determine the value _{X P} of the X-coordinate of the reference point 13c. When the Z-axis angle is determined by taking the midpoint of the operable region 10, there are two discontinuous locations (see FIG. 31). In this embodiment, the midpoint of the width of the X coordinates of the two points and the value of X _P.

Next, to determine the Y coordinate _{Y P} of the reference point 13c. As shown in FIG. 32, the X-coordinate X _P of the determined reference point, the value of Y coordinate for the conditional operation area 10a is wide. Therefore, in the present embodiment, a maximum value and the minimum value of the width of the Y-coordinate, to determine the value of the reference point Y coordinate Y _P by taking their midpoints.

  In the present embodiment, the angle of the Z axis is determined by two methods of taking the midpoint of the operable region 10 and a method along the straight line 13. In the operation plan, the influence of the arc 4a on the surface of the workpiece 3 can be suppressed by determining the angle of the Z axis of the three-dimensional rotary table 1 while switching between these two methods.

  In the present embodiment, the intersection of the straight line 13 and the operable region 10 for determining the Z-axis angle is obtained on a two-dimensional coordinate system, and two methods for obtaining the Z-axis angle at the position of the intersection are switched. Further, since the straight line 13 connects the operable region 10 and the operable region 10, two intersections between the straight line 13 and the operable region 10 for determining the angle of the Z axis are obtained.

First, the first intersection is obtained. Go adding _{Y P} one by one along the straight line from the Y-coordinate _{Y P} of reference points 13c of the straight line 13. The position of the value of each Y _P, X coordinates determined by taking the value X _P of the X-coordinate at that time, the midpoint of the operating region 10 at the position of the Y coordinate obtained by adding 1 to the current Y _P And take the absolute value of the difference between these values (see FIG. 33A). If this value is equal to or less than 2.0 ° change in the angle of the three-dimensional turntable 1 used to determine the inclination of the straight line 13, the Z-axis angle of the three-dimensional turntable 1 is continuous. determining, for the intersection of the Y-coordinate value Y _P of the current Y coordinate. Since the determined position of the Y coordinate is on the straight line 13, the X coordinate can be determined according to the straight line 13, and the determination of the angle of the Z axis along the straight line 13 is started for the point (X _P , Y _P ). Suppose that it is an intersection.

Moreover, two locations th intersection reduces from the position of the reference point 13c of the straight line 13 the value of Y _P one by one, and the X-coordinate X _P on the line 13 at the position of the value of each Y _P, the current Y _The X coordinate obtained by taking the midpoint of the operable region 10 at the position of the Y coordinate obtained by subtracting 1 from _P is obtained, and the absolute value of the difference between these values is taken (see FIG. 33B). If this value is an angle change of 2.0 ° or less determined from the rotational speed of the three-dimensional rotating table 1, it is determined that the Z-axis angle of the three-dimensional rotating table 1 is continuous, and the Y coordinate of the intersection point the value and the value of the current Y _P. Similar to the case of obtaining the positive direction of the intersection, the position of the determined Y coordinate is the upper straight 13, X-coordinate of the two points th intersection can determine the X _P from the equation of the straight line 13 .

  Next, the position change of the straight line 13 will be described. If there is an inoperable region 11 on the straight line 13 for determining the Z-axis angle, the Z-axis angle cannot be determined along the straight line 13. Therefore, the position of the reference point 13c of the straight line 13 is changed so as to avoid the inoperable region 11. Further, in the present embodiment, the direction in which the reference point 13c of the straight line 13 is moved is determined according to which range of the straight line 13 the inoperable region 11 is detected.

  Here, in the straight line 13 shown in FIG. 25 and FIG. 26, the right side portion where the X coordinate value is larger than the reference point 13 c and the left side where the X coordinate value is small, with the position of the reference point 13 c of the straight line 13 as the boundary. I thought it was divided into parts.

  In this embodiment, the straight line 13 drawn for determining the angle of the Z-axis has a positive slope, and thus becomes a straight line 13 on the upper right when viewed in the two-dimensional coordinate system. Therefore, when the inoperable region 11 is detected at a position on the right side of the reference point 13c, the reference point 13c is moved in the negative direction of the Y-axis of the two-dimensional coordinate system, and the reference point 13c of the straight line 13 is moved. When the inoperable region 11 is detected at the left position, the region is moved in the positive direction of the Y axis of the two-dimensional coordinate system. Thus, the possibility that the straight line can avoid the inoperable region 11 is considered high.

  However, depending on the position of the inoperable area 11, the straight line 13 may not avoid the inoperable area 11 even if the position of the reference point 13 c is changed. Therefore, in such a case, by reducing the inclination of the straight line 13, the straight line is made almost horizontal, and the amount of change in the Z-axis angle when moving to the next welding location 6 a is increased, thereby making the operation impossible region. 11 can be avoided.

  However, when the straight line 13 for determining the Z-axis angle is moved, even if the inoperable area 11 can be avoided, it may not intersect with the operable area 10. As indicated by A in FIG. 34, when the shape of the operable region 10 is curved, depending on the position of the reference point 13c for drawing the straight line 13, the straight line 13 and the operable region 10 are Do not cross. Even in such a state, in order to determine the Z-axis angle, in this embodiment, when there is no intersection of the straight line 13 and the operable region 10, in the two-dimensional coordinate system as shown in FIG. The angle of the Z axis was determined using the straight line 14.

When the straight line 13 for determining the Z-axis angle does not intersect the operable region 10, the straight line 14 parallel to the Y axis that connects the straight line 13 and the operable region 10 is set by the following procedure.
(1) When there is no intersection of the straight line 13 for determining the angle of the Z axis on the discontinuous axis of the operable region 10 and the operable region 10, the point from which the operable region 10 becomes discontinuous to the Y axis Draw a parallel straight line 14.
(2) Find the intersection of a straight line 13 for determining the angle of the Z axis and a straight line 14 parallel to the Y axis.
(3) It is confirmed that there is no inoperable region 11 between the point where the operable region 10 becomes discontinuous and the intersection obtained in (2) above.

  When the inoperable region 11 is detected on the straight line 14 parallel to the Y axis, the position of the straight line 14 is moved from the position of the discontinuous point in the positive direction of the X axis. In the case of FIG. 35, the straight line 14 parallel to the Y axis is moved to the right of the image. By using this method, the Z-axis angle can be determined even in a situation where the straight line 13 for determining the Z-axis angle and the operable region 10 are divided by the inoperable region 11. Can do.

  FIG. 37 is a pgm image showing a state in which the Z-axis angle is determined using the straight line 13 passing through the conditional operable region 10a. In this image, the pgm image used to determine the Z-axis angle is determined by the line 12 representing the Z-axis angle determined by taking the midpoint of the operable region 10 and the straight line passing through the conditional operable region 10a. The Z-axis angle line 13 is added.

[Operation plan of Cartesian coordinate manipulator 2]
In the operation plan of the rectangular coordinate type manipulator 2 performed in the present embodiment, the operation plan in which the tip of the welding torch 4 attached vertically downward to the hand link 2d of the manipulator 2 is applied to the welded portion 6 of the workpiece 3 after the posture change is made. Do. In addition, an operation plan of the hand link 2d of the manipulator 2 is performed, and an operation plan is performed so that the welding torch 4 and the hand link 2d do not contact the workpiece 3 and the three-dimensional rotary table 1 during the welding operation. In addition, in this embodiment, in order to apply the welding torch 4 to all the welding locations 6 of the workpiece 3, the three-dimensional turntable is set so that all the welding locations 6 of the workpiece 3 are located within a range in which the welding torch 4 can move. The positional relationship between 1 and the Cartesian coordinate manipulator 2 was determined.

  First, the operation plan of the hand link 2d of the rectangular coordinate manipulator 2 will be described.

In the present embodiment, by changing the angle of the hand link 2d so that the welding torch 4 follows the line segment connecting the current welding point 6 and the next welding point 6, the hand link 2d of the manipulator 2 or the welding It was considered that the possibility of contact between the torch 4 and the branch pipe 3b of the work 3 could be suppressed. Angle of the hand link 2d in this process is represented by the angle phi _a of FIG. 38. This angle can be obtained on the XY plane of the absolute coordinate system.

  From the above-described mechanism of the rectangular coordinate type manipulator 2, the initial position of the hand link 2d coincides with the positive direction of the Y axis of the absolute coordinate system. Therefore, the angle formed by the line segment connecting the Y axis of the absolute coordinate system and the two welding locations 6 can be obtained as the angle of the rotary joint 2e of the hand link 2d.

  Thus, by changing the angle of the rotary joint 2e of the hand link 2d, the welding torch 4 can operate so as to go around the branch pipe 3b of the workpiece 3 (see FIG. 39). Therefore, in this embodiment, this method is used to avoid contact between the branch pipe 3b of the workpiece 3, the hand link 2d of the orthogonal coordinate manipulator 2, and the welding torch 4.

  However, since the workpiece 3 is fixed to the chuck 1d of the three-dimensional rotating table 1, as shown in FIG. 40, when the branch pipe 3b of the workpiece 3 is oriented vertically upward, the chuck 1d. And the branch pipe 3b of the work 3 are narrowed. Therefore, when the hand link 2d moves so as to wrap around the branch pipe 3b, the hand link 2d may not be included in the width indicated by gap in FIG. In addition, since the chuck 1d for fixing the workpiece 3 is large, there may be a situation where the hand link 2d of the Cartesian coordinate manipulator 2 cannot pass over the chuck 1d (see FIG. 41). In such a case, in the present embodiment, in order to avoid the chuck 1d, the method for determining the angle of the hand link 2d of the rectangular coordinate manipulator 2 is changed.

  The second method for determining the rotation angle of the rotary joint 2e of the hand link 2d is such that the line link connecting the current welding point 6 and the next welding point 6 and the hand link 2d form an angle of 90 °. The rotation angle of the rotary joint 2e of the hand link 2d is determined.

Rotation angle of the rotary joint 2e of the hand link 2d determined in this way is represented by the angle phi _L shown in FIG. 42. By setting this angle as the rotation angle of the rotary joint 2e of the hand link 2d, the welding torch from the top of the branch pipe 3b to the welding point 6 without the hand link 2d entering the part where the branch pipe 3b and the chuck 1d are close to each other. 4 can be applied (see FIG. 40). In this embodiment, this method avoids contact between the hand link 2d of the Cartesian coordinate manipulator 2 and the chuck 1d of the three-dimensional rotating table 1.

  In order of welding the welding locations 6 of the workpiece 3, first, welding is started from the welding locations 6 on the side surface of the workpiece 3, and the welding locations 6 in the direction close to the chuck 1d are successively welded. And it returns to the welding location 6 which started welding via the welding location 6 of the side surface on the back side of the side which started welding.

  In the first half of the welding operation, since the hand link 2d of the Cartesian coordinate manipulator 2 is close to the chuck 1d, the possibility of contact between the hand link 2d and the chuck 1d is high. Therefore, in this embodiment, in order to avoid contact with the chuck 1d, the hand tip is formed so as to form an angle of 90 ° with the welding line 7 from the welding start point which is the first half of the welding operation to the point on the back side thereof. The angle of the link 2d is determined. The angle of the rotary joint 2e of the hand link 2d is determined so as to follow the weld line 7 from the back side point in the latter half of the welding operation to the welding start point.

  In these two methods, the angle formed by the welding joint 7 and the rotary joint 2e of the hand link 2d is different by 90 °. These two methods are switched at the welding point 6 on the back side of the welding point 6 where welding is started. When the welding torch 4 is combined with the welding point 6 for switching between the two methods, the hand link 2d is positioned so that the welding torch 4 is along the welding line 7 in the same diameter pipe (see FIG. 43A). Therefore, when switching from the state in which the weld line and the hand link 2 d form 90 ° to the state along the weld line 7, the weld line 7 can be continued as it is.

  However, in the case of a different diameter pipe, the hand link 2d is not in a state along the weld line 7 (see FIG. 43B). Therefore, when the method of determining the angle of the hand link 2d is switched, the angle changes greatly in order to follow the weld line 7. In order to prevent this, in the welding operation of different diameter pipes, the welding operation is performed in a state in which the weld line 7 and the hand link 2d form an angle of 90 ° at all the welding locations 6.

  Next, the positional relationship between the rectangular coordinate manipulator 2 and the three-dimensional rotary table 1 will be described.

  In order to apply the welding torch 4 to the welding locations 6 of all the workpieces 3, all the welding locations 6 of the workpieces 3 must be within a range in which the tip of the welding torch 4 can be moved by the orthogonal coordinate manipulator 2. When the posture of the workpiece 3 is changed by three axes from the above-described mechanism of the three-dimensional rotary table 1, the position of the welded portion 6 of the workpiece 3 is changed around the rotation axis of the Z axis. Therefore, in the present embodiment, first, a range in which the tip of the welding torch 4 can be moved by the operation of the rectangular coordinate manipulator 2 is obtained, and the three-dimensional turntable 1 is installed at the center of the range.

  The range in which the welding torch 4 can move is based on the position of the welding torch 4 when the translation distance 0 (mm) of the three linear sliders 2a, 2b and 2c and the rotation angle of the hand link 2d is 0 °. . FIG. 44 shows a range in which the welding torch 4 can be obtained from the movable range of the rectangular coordinate manipulator 2. FIG. 44A is an image viewed from the positive direction of the X axis in the absolute coordinate system, and represents a range in which the welding torch 4 can move in the Y axis direction and the Z axis direction. It is possible to move 400 mm in the positive direction of the Y axis and the positive direction of the Z axis. FIG. 44B is an image of the orthogonal coordinate manipulator 2 viewed from the positive direction of the Z axis of the absolute coordinate system, and represents a range in which the welding torch 4 can move in the X axis direction. The range of movement in the X-axis direction is 400 (mm) when the linear slider 2a is movable, but the hand link 2d can be rotated up to 90 ° in both the positive and negative directions by the rotating joint. It has a width of 600 (mm) including the length of the link 2d.

  The three-dimensional turntable 1 was installed so that the center of the pedestal serving as the origin of the work coordinate system of the three-dimensional turntable 1 is located in the center of the range in which the welding torch 4 shown above can move.

(Operation planning experiment)
In the present embodiment, an operation plan experiment for a T-shaped or Y-shaped workpiece 3 was performed using the created motion planning program. In addition, the status of the operation planned using the welding operation confirmation simulator is displayed, and whether or not the hand link 2d and the welding torch 4 of the Cartesian coordinate manipulator 2 are in contact with the three-dimensional rotary table 1 and the workpiece 3 during the operation. Was confirmed visually.

[Work shape for welding operation planning]
The shape of the aluminum pipe, which is the work 3 set in the operation planning experiment conducted this time, includes the following six types in consideration of the difference in angle between the main pipe 3a and the branch pipe 3b and the difference in diameter between the main pipe 3a and the branch pipe 3b. It was set.
(1) T-shaped with the same diameter (angle 91.1 ° tube diameter 140 (mm))
(2) T-shaped with different diameter (angle 91.1 ° main pipe diameter 89 (mm) branch pipe diameter 63 (mm))
(3) Same diameter Y-shaped (angle 75 ° tube diameter 89 (mm))
(4) Same-diameter Y-shape (angle 45 °, tube diameter 114 (mm))
(5) Different diameter Y shape (angle 75 ° main pipe diameter 114 (mm) branch pipe diameter 89 (mm))
(6) Different diameter Y-shaped (angle 45 ° main pipe diameter 89 (mm) branch pipe diameter 63 (mm))

  For these six types of workpieces 3, an automatic welding operation plan by an automatic welding work device and a planned operation display by an operation confirmation simulator were performed.

  In the motion planning method proposed in the present embodiment, it is necessary to determine an angle at which the welding torch 4 is tilted and applied to the welded portion 6 of the workpiece 3 as a motion planning parameter. In the welding operation planning experiment conducted this time, the operation planning was performed when this angle was 10 °, 20 °, and 30 °.

  In addition, when the workpiece 3 is a pipe having the same diameter, when the two pgm images are overlapped, the minimum allowable width in which the operable region 10 is continuous from the upper end to the lower end in the shape of each workpiece 3 is investigated. The pgm image created with the investigated allowable width and the pgm image created with the allowable width of 0.05 (mm) were used in an overlapping manner.

  In the operation planning experiment of the workpiece 3 of each shape, the planned welding operation was displayed using an operation confirmation simulator. Further, by stopping the reproduction of the operation confirmation simulator operation during the display of the planned welding operation and changing the viewpoint, the position of the hand link 2d of the welding torch 4 and the Cartesian coordinate manipulator 2 and the workpiece 3 are changed. By confirming the posture and the position of the frame of the three-dimensional turntable 1, it was confirmed that these devices were not in contact.

[Operation reproduction method and function by operation confirmation simulator]
FIG. 45 is a screen of the operation confirmation simulator created in the present embodiment. The operation check simulator draws the Cartesian coordinate manipulator 2, 3D turntable 1, and workpiece 3 with 3D-CG using OpenGL, and stops the display / playback operation halfway. A function to change the position was added. The screen of the operation confirmation simulator is centered on the workpiece 3 attached to the three-dimensional rotary table 1. In addition, a zoom function is also provided, and the center portion of the screen can be enlarged by zooming. These functions include the fact that the welding torch 4 is inclined and applied to the welded portion 6 of the work 3, and whether the welding torch 4 and the hand link 2d and the work 3 or the hand link 2d and the three-dimensional turntable 1 are in contact with each other. It is for confirming. Therefore, in the operation plan performed in the present embodiment, using these functions, the posture of the workpiece 3 and the operation of the Cartesian coordinate manipulator 2 at each welding point 6 and the presence / absence of contact of each equipment are visually confirmed.

  In order to display the planned operation using the operation confirmation simulator, the three-axis rotation angle of the three-dimensional rotary table 1 at each welding point 6 and the linear motion sliders 2a and 2b constituting the orthogonal coordinate type manipulator 2 are used. , 2c and the rotation angle value of the hand link 2d of the Cartesian coordinate manipulator 2 are used. Therefore, in this embodiment, as a result of the operation plan by the operation plan program, values necessary for displaying the operation by the operation confirmation simulator are output to one file. The operation confirmation simulator displays the planned operation by reading the output file.

[Experimental results and discussion]
The result of the motion planning experiment and the state of the planned motion are shown. In the motion planning experiment, the execution time of the motion planning program was also verified.

  First, FIG. 46 to FIG. 48 show the results of creating pgm images for six types of workpieces 3 having different shapes shown in the experimental outline. In addition, the line 12 showing the angle of the Z axis | shaft of the planned three-dimensional turntable 1 was shown and added to the pgm image to publish. The angle at which the welding torch 4 is tilted when the welding torch 4 is applied to the welded portion 6 of the workpiece 3 is 20 °.

  FIG. 46 is a pgm image showing a T-shaped motion plan result of the same diameter and different diameters. In the case of the T-shape, only two pgm images created by changing the allowable width L in the equation (5) were used in the case of the same diameter tube. Allowable widths when creating a pgm image were 0.05 (mm) and 1.5 (mm), and the Z-axis angle was determined from the operable region 10 and the conditional operable region 10a. In addition, the allowable width in the case of a different diameter pipe is 0.05 (mm).

  In the case of the same-diameter T-shaped in FIG. 46A, the discontinuity of the operable region 10 due to the refraction of the welding line 7 on the side surface of the same-diameter pipe described above is changed to the straight line 13 passing through the conditional operable region 10a. It can be confirmed that the determination of the Z-axis angles of all the welded portions 6 can be performed by determining the Z-axis angles along the lines. Further, in the case of the different diameter T-shaped in FIG. 46B, it can be confirmed that the Z-axis angle can be determined from within the operable region 10.

  FIG. 47 shows a Y-shaped operation plan result when the angle of the center line is 75 °. In the case of this work 3, an operation plan was made by superimposing two pgm images only on the same diameter tube as in the case of the T-shape. In the case of the same diameter pipe, the allowable width is 0.05 (mm) and 1.2 (mm). In the case of a different diameter tube, it is 0.05 (mm) as with the different diameter T-shaped. In the case of the same-diameter Y-shape having an angle of 75 ° in FIG. Therefore, the angle of the Z-axis of all the welding locations 6 can be determined by connecting the operable region 10 with the straight line 13 passing through the conditional operable region 10a.

  Also, in the case of the different-diameter Y-shape with an angle of 75 ° in FIG. 47 (b), the Z-axis of all the welding locations 6 can be obtained by taking the midpoint of the operable region 10 as in the different-diameter T-shape. The angle can be determined.

  FIG. 48 shows the result of the Y-shaped operation plan with the center line angle of 45 °. In the case of a 45 ° Y-shape, a portion where the operable region 10 does not exist appears depending on the movable range of the three-dimensional rotary table 1. Therefore, two pgm images in which the allowable width L in equation (a) was changed regardless of the same diameter and different diameters were used in an overlapping manner. The allowable width is 0.05 (mm) and 1.2 (mm) for both the same diameter pipe and the different diameter pipe. In the case of the same-diameter Y-shape with an angle of 45 ° shown in FIG. 48A, the refraction of the welding line 7 in the case of the same-diameter pipe described above and the operable region 10 by the movable range of the three-dimensional rotary table 1 An operation is planned in which the discontinuities are connected by a straight line 13 passing through the conditional operable region 10a.

  48B, the discontinuity of the operable region 10 due to the movable range of the three-dimensional rotary table 1 passes through the conditional operable region 10a. It can be confirmed that the angle of the Z axis can be determined by connecting with the straight line 13. FIG. 49 is an enlarged view of the discontinuous portion of the operable region 10 due to the movable range of the three-dimensional rotary table 1 in the image of the operation result in the case of the 45 ° different-diameter Y-shape shown in FIG. It is an image. In B in FIG. 49, since there is no intersection of the straight line 13 for determining the Z-axis angle and the operable region 10, the Z-axis angle is determined using the straight line 14 parallel to the Y-axis planned above. You can see how you did it.

  In the motion planning experiment performed in the present embodiment, it was possible to plan the welding operation on the workpieces 3 having all the shapes shown in the outline of the experiment. If there is a discontinuity in the operable region 10, it can be confirmed that the Z-axis angle is correctly determined using the straight line 13 having an inclination of 0.5 passing through the conditional operable region 10a. It was.

  However, in the operation plan result of the same-diameter Y-shape with an angle of 45 °, when the straight line 12 representing the Z-axis angle determined in the range where the operable region 10 does not exist due to the movable range of the three-dimensional rotary table 1 is seen, It can be confirmed that it passes through the vicinity of the boundary between the impossible area 11 and the conditionally operable area 10a (see FIG. 50).

  As described above, when the Z-axis angle is determined, the welding operation is performed near the boundary between the movable range and the movable range of the three-dimensional rotary table 1. Therefore, when the posture of the workpiece 3 is changed due to an unexpected abnormal operation or the like, it is considered that the movable range of the three-dimensional rotary table 1 is exceeded. When such a situation occurs, there is a possibility that the arc 4a hits other than the welded portion 6.

  Therefore, when the inoperable region 11 is within a range of ± 10 ° of the X coordinate of the determined Z-axis angle straight line, the position of the straight line 13 for determining the Z-axis angle is determined as the inoperable region. It is considered that an operation plan that changes the position by moving in a direction away from 11 and refrains from determining the Z-axis angle near the boundary between the inoperable region 11 and the conditional operable region 10a is considered necessary. . As indicated by C in FIG. 50, when the inoperable region 11 is in the vicinity of the straight line 13 on the right side of the reference point of the straight line 13, the straight line 13 is directed downward to move away from the inoperable region 11. Move to.

  Next, measurement of the execution time of the motion planning program will be described. In the present embodiment, the case of a different diameter T-shape that is considered to require the least time for execution, and the case of the same-diameter Y-shape having a 45 ° center line angle that is considered to require the most time for execution. Was measured. The operation planning program is created on Debian Linux (registered trademark). The computer CPU used for measuring the execution time is INTEL Celeron d 2.13 GHz (registered trademark), the memory is 512 MB, and the compiler used is gcc (GNU). (Compiler Collection) version 3.3.5. In addition, optimization is performed by adding the -O2 option as a compile option.

  First, the time required for the operation plan of the different diameter T-shape considered to have the least calculation process was 47.241 (s). Moreover, the time for the 45 ° same-diameter Y-shaped motion plan, which is considered to have the most calculation processes, was 83.404 (s). The difference in the time required for the operation plan is considered to be related to the presence or absence of discontinuity in the operable region 10. In addition, since it is approximately 83 (s) even in the same-diameter Y-shape having an angle of 45 °, which requires the most time, the welding operation of the workpiece 3 can be performed in a sufficiently practical time using the created motion planning program. You can plan.

[Operation check by operation check simulator]
A state in which the result of the motion planning experiment in the Y-shape with the same diameter of 45 ° among the six types of workpieces 3 for which the motion planning has been performed is displayed by the motion confirmation simulator. In this operation plan, the Z-axis is formed by connecting a point where the operable region 10 becomes discontinuous due to the refraction of the welding line 7 and a point where the operable region 10 becomes discontinuous due to the movable range of the three-dimensional rotary table 1 by a straight line. You can see how the angle has been determined. For this reason, all the Z-axis angle planning methods used in the welding operation planning program based on the three-axis rotation performed in this embodiment could be confirmed.

  51 to 53 are images showing a state when the operation is displayed by the operation confirmation simulator. These images are seen from the negative direction of the X axis of the absolute coordinate system described above. In these images, the passage of time is shown in alphabetical order, and the welding operation is shown successively in the order of FIGS. 51, 52, and 53. In addition, images of the same operation confirmed from different viewpoints are simultaneously shown as images with “′” added to the alphabet representing time. In this image, the operation is confirmed by moving the viewpoint to a position where it can be confirmed that the welding torch 4 and the hand link 2d are not in contact with the workpiece 3 or the three-dimensional rotary table 1.

  When the operation of the three-dimensional turntable 1 is seen throughout FIGS. 51 to 53, it can be confirmed that the rotation of the Z-axis is almost complete. In addition, the angle of the Z axis of the three-dimensional rotary table 1 changes greatly between FIGS. 51 (C) to 52 (F). This change in the Z-axis angle is determined when the Z-axis angle is determined by connecting the straight line 13 passing through the conditional operable region 10a at the discontinuous portion of the operable region 10 due to the refraction of the weld line 7. It is. Here, since the angle of the Z-axis is determined along a straight line having an inclination of 0.5, the angle of the Z-axis changes by 2.0 ° every time the welding spot 6 changes by one. For this reason, the angle of the Z axis has changed greatly. Similarly, a large change in the angle of the Z axis between FIGS. 52 (G) to 53 (J) is caused by connecting the discontinuous portions of the operable region 10 by the movable range of the three-dimensional rotary table 1 with a straight line. It seems that the angle has been determined. Here again, the Z-axis angle is determined along the straight line 13, and the Z-axis angle changes by 2.0 ° every time the position of the welding point 6 changes, so the Z-axis motor 1c rotates greatly. ing.

  Next, the operation of the hand link 2d of the rectangular coordinate manipulator 2 will be described. 51 (A) to 52 (F), the chuck 1d of the three-dimensional rotating table 1 is rotated upward by changing the posture of the workpiece 3. Therefore, as planned in order to avoid the above-described chuck 1d, the hand link 2d operates while maintaining an angle of 90 ° with respect to the weld line 7.

  Further, between FIGS. 52 (G) to 53 (K), the chuck 1d of the three-dimensional rotating table 1 moves downward, and the branch pipe 3b of the work 3 rotates upward again. It can be confirmed that it will come. Therefore, the angle of the hand link 2d is changed so as to follow the weld line 7 of the workpiece 3 as planned in order to avoid the above-described branch pipe 3b, and the hand link 2d goes around the branch pipe 3b. It could be confirmed.

  Further, in the operation confirmation performed this time, the contact between the welding torch 4 and the hand link 2d, the three-dimensional rotary table 1 and the workpiece 3 during operation was confirmed. From the images confirmed by changing the viewpoint, it was confirmed that the equipment did not touch each other.

  In the present embodiment, an operation planning method for an automatic welding work apparatus using a posture change of the workpiece 3 by three-axis rotation of the three-dimensional rotating table 1 is proposed, and an operation planning program and an operation confirmation simulator for performing the proposed operation planning. It was created. When the operation planning method proposed in this embodiment is used to plan the welding operation of the workpiece 3, the difference in the angle between the main pipe 3a and the branch pipe 3b, the diameter, and the welding torch 4 is tilted to the welding location 6 of the workpiece 3. Regardless of the inclination angle of the welding torch 4 when it is applied, the operation of the automatic welding apparatus for welding the T-shaped or Y-shaped workpiece 3 could be planned.

  Further, when the operation planned by the operation planning program is confirmed using an operation confirmation simulator, the work link 3d of the welding torch 4 or the Cartesian coordinate manipulator 2, the work 3 and the three-dimensional turntable 1 come into contact with each other. It was confirmed that the welding operation could be performed.

  In this embodiment, the time of the calculation process necessary for the operation plan is measured. As a result, the time required for performing the motion plan is 83.404 (s) at the longest, and when the motion plan is performed by the worker, the operation plan takes time, and it does not become uncomfortable. It was found that the operation plan can be performed in a sufficiently practical time.

  In addition, this invention is not limited to the said embodiment, Of course, correction and a change can be added within the scope of the present invention. For example, in the above-described embodiment, the motor is exemplified as the configuration of the drive unit. However, the present invention is not limited to this, and it is needless to say that various fluid pressure cylinders and other drive means may be used. Moreover, although each rotating member showed the example directly connected to the motor shaft of the motor, you may make it connect via a speed-reduction mechanism.

  In the present embodiment, the workpiece has been described as an example of the same diameter T-shape, the different diameter T-shape, the same diameter Y-shape, and the different diameter Y-shape. However, the present invention is not limited to this. May be a workpiece having a different shape such as a cylinder.

  Moreover, the connection shape of a workpiece | work is not restricted to T character and Y character, Various joining shapes, such as L character and X character, may be sufficient. Furthermore, the welding method may be not only TIG welding but also plasma welding and laser welding.

The whole block diagram of the welding operation apparatus which shows embodiment of this invention Schematic diagram showing the mechanism of the three-dimensional turntable Perspective view showing mechanism of Cartesian coordinate manipulator It is the schematic which shows the movable range of a three-dimensional turntable, Comprising: (a) is a figure which shows the movable range of a Y-axis, (b) is a figure which shows the movable range of an X-axis. Schematic showing the movable range of the rotary joint of the hand link of the Cartesian coordinate manipulator Diagram showing the state of flat plate automatic welding experiment Diagram showing the direction vector at the weld location The perspective view which shows the absolute coordinate in a welding operation apparatus It is a figure which shows the inclination angle of a welding torch, Comprising: (a) is a figure which shows the state where a welding torch is vertically upward, (b) is a figure which shows the state which inclined the welding torch from the vertically upward direction It is the schematic which shows the direction where an arc spreads, Comprising: (a) is a figure which shows the case where the centerline of a welding line and a welding torch makes an angle of 90 degrees, (b) is the centerline of a welding line and a welding torch 0 Diagram showing an angle of ° The figure which shows the welding width of the condition regarding Y coordinate It is a figure which shows direction of the front-end | tip of a welding torch, Comprising: (a) is a figure which shows the case where a welding torch is inclined in the advancing direction, (b) is a figure which shows the case where the welding torch is inclined opposite to the advancing direction Diagram showing the working coordinate system of the main pipe, the reference point on the branch pipe, and the weld line along the branch pipe FIG. 4 is a diagram showing reference points on the circumference of a branch pipe, where (a) shows a state in which the main pipe and the branch pipe overlap each other, and (b) shows an angle representing a point on the circumference of the branch pipe. Figure It is the schematic which shows the mechanism of a three-dimensional turntable, Comprising: (a) is a figure which shows the state which is not adding the rotation of a Z-axis, (b) is a figure which shows the state which added the rotation of a Z-axis Flow chart of operation plan of 3D turntable The figure which shows the pgm image in the case of welding the pipe from which the diameter of a main pipe and a branch pipe differs in T shape The figure which added the line showing the Z-axis angle determined to FIG. The figure which shows the weld line of the side when the diameter of a main pipe and a branch pipe is the same The figure which shows a pgm image in the case of welding a pipe with the same diameter of a main pipe and a branch pipe to a T shape The figure which shows a pgm image in the case of having a range where there is no operable region in the welding of the main pipe and the branch pipe It is a figure which shows the pgm image which changed the allowable width | variety, Comprising: (a) is a figure which shows the case where an allowable width is 0.05 mm, (b) is a figure which shows the case where an allowable width is 1.5 mm The figure which shows the image which overlapped the pgm image of (a) of FIG. 22, and the pgm image of (b). Figure with 2D coordinates added to Figure 23 Detailed view showing a straight line for determining the Z-axis angle via the position where the Z-axis angle is 0 ° Detailed view showing a straight line for determining the Z-axis angle via the position where the Z-axis angle is 0 ° in the case where there is no operable region Flow chart for drawing a straight line for determining the Z-axis angle Diagram showing the width of the conditionally operable area when the Z-axis angle is 0 ° The figure which added two straight lines used when setting the reference point to FIG. 25 FIG. 25 is a diagram showing an allowable width of two straight weld lines used when setting the reference point. The figure which shows the discontinuous part of the two operable areas The figure which shows the tolerance width of the welding location in the Z-axis angle of a reference point It is a figure which shows the intersection of the straight line for determining a Z-axis angle, and a operable | movable area | region, Comprising: (a) is a figure which shows the case where it searches in the positive direction of X-axis, (b) is the negative direction of X-axis. Figure showing the case of searching Diagram showing a case where there is no intersection between the straight line passing through the reference point and the operable area The figure which shows the state which added the straight line of the vertical direction to FIG. FIG. 35 is a diagram illustrating a state in which the inoperable region is expanded. The figure which added the line of the Z-axis angle determined in FIG. The figure which shows the state of the hand link which follows the welding line The figure which shows the state where the hand link wraps around the branch pipe The figure which shows the state where the branch pipe and the chuck are close The figure which shows the state which applied the welding torch to the welding location from the upper direction of a chuck | zipper The figure which shows the state which moved the hand link on the branch pipe It is a figure which shows the state which applied the welding torch to the welding location of the back side of a welding start point, (a) is a figure in case the diameter of a main pipe and a branch pipe is the same, (b) differs in the diameter of a main pipe and a branch pipe. Case illustration It is a figure which shows the range which a welding torch can move, Comprising: (a) is a figure which shows the range which a welding torch can move to a Y-axis direction and a Z-axis direction, (b) is the range which a welding torch can move to an X-axis direction. Illustration The figure which shows the screen of the simulator for operation check It is a figure which shows the T-shaped operation plan result, Comprising: a) The figure when the diameter of a main pipe and a branch pipe is the same, (b) is the figure when the diameter of a main pipe and a branch pipe differs It is a figure which shows the operation plan result of the Y shape joined at an angle of 75 degrees, Comprising: (a) is a figure when the diameter of a main pipe and a branch pipe is the same, (b) is the case where the diameters of a main pipe and a branch pipe differ Figure It is a figure which shows the Y-shaped operation plan result joined at an angle of 45 degrees, Comprising: (a) is a figure when the diameter of a main pipe and a branch pipe is the same, (b) is the case where the diameters of a main pipe and a branch pipe differ Figure The figure which shows the state which correct | amended the intersection of the straight line which passes a reference point, and an operable area | region Diagram showing a straight line passing through the boundary between the operable area and the inoperable area The figure which shows the state of the display with the simulator for operation check The figure which shows the state of the display with the simulator for operation check The figure which shows the state of the display with the simulator for operation check

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 3D turntable 1a X-axis motor 1b Y-axis motor 1c Z-axis motor 1d Chuck 2 Cartesian coordinate manipulator 2a X-axis linear slider 2b Y-axis linear slider 2c Axis linear slider 2d Hand link 2e Rotary joint 3 Work 3a Main pipe 3b Branch pipe 4 Welding torch 4a Arc 5 Aluminum flat plate 6 Welded part 6a Next welded part 6b Reference point 7 Welding line 8 Welded part 8a Next welded part 9 Filler wire 10 Operable area 10a Conditionally operable area 11 Inoperable Area 12 A straight line 13 indicating the Z-axis angle A straight line 13a determining the Z-axis angle A straight line 13b passing through the boundary between the operable area and the inoperable area 13c A straight line 13c passing through the boundary between the operable area and the inoperable area Reference point 13d Boundary point 13e between the conditionally operable area and the inoperable area 13e Boundary point between the conditionally operable area and the inoperable area 14 Straight line 101 drawn parallel to Y axis Input unit 106 Control unit 106a Welding line calculation unit 106b Rotation angle calculation unit 106c of three-dimensional rotary table Control calculation unit 107 of rectangular coordinate manipulator Display unit

Claims (9)

It can be rotated around three axes: the input part for inputting the welding conditions of the workpiece to be welded, the Z axis as the vertical axis, the Y axis as the horizontal axis perpendicular to the Z axis, and the X axis perpendicular to the Y axis. Based on input information from the input unit, a three-dimensional rotary table for changing the posture of the workpiece, a rotary table driving unit for driving the three-dimensional rotary table, a welding torch holding unit for holding the welding torch vertically downward And a control unit for controlling the turntable drive unit,
The control unit calculates the coordinate position in the absolute coordinate system of all the welding locations based on the information from the input unit, the center line of the welding torch is always located on the XZ plane of the absolute coordinate system, and the current The three axes of the rotary table drive unit so that the weld line is included in a predetermined permissible width L that is delimited by a plane parallel to the XY plane, where a line segment formed by the next weld location is a weld line. A welding work device characterized by calculating a rotation condition and controlling the rotation of the turntable drive unit. The welding torch holding part is movable along the three axes X, Y, and Z directions orthogonal to each other, and the control part moves the welding torch based on input information from the input part. The welding apparatus according to claim 1, wherein the welding apparatus is controlled. The welding operation apparatus according to claim 1, wherein the control unit performs a calculation so that a Z coordinate of a next welding location is smaller than a Z coordinate of a current welding location. The control unit is inclined at a predetermined angle with respect to the welding line in a direction opposite to the traveling direction of the welding torch within the allowable width defined by a plane parallel to the XZ plane of the absolute coordinate system XYZ. The welding work apparatus according to any one of claims 1 to 3, wherein a three-axis rotation condition of the turntable drive unit is set so that welding can be performed in a posture. 2. The control unit according to claim 1, wherein the control unit inputs at least the following determination formulas and calculates a three-axis rotation condition of the three-dimensional turntable so as to satisfy these determination formulas at each welding position. Welding work device.
(A) | Y coordinate of the current welding location−Y coordinate of the next welding location | <L (mm) (where Y is the Y coordinate of the absolute coordinate system, L is the allowable width on both sides of the X axis)
(A) Z coordinate of the current weld location> Z coordinate of the next weld location The said control part further inputs the following judgment formulas, and calculates the three-axis rotation conditions of the said three-dimensional turntable so that these judgment formulas may be satisfied at each welding position. Welding work device. However, A and B are angles when the counterclockwise rotation angle of each axis XYZ of the work coordinate system with the origin at the base center of the three-dimensional rotating table is positive and the clockwise rotation angle is negative.
(C) -A ≦ X axis rotation angle ≦ A (however, 0 ° <| A | <180 °)
(D) -B ≦ Y axis rotation angle ≦ B (however, 0 ° <| B | <90 °) The controller is
1) For each welding position, while rotating the Z-axis of the three-dimensional rotary table by 360 °, it is determined whether or not the workpiece posture satisfying the determination formula can be taken at each Z-axis angle. It is divided into cases where there is no
2) When the calculation in 1) above for all welding positions is completed, the Z-axis angle that satisfies the above-mentioned determination formula while maintaining the change rate of the Z-axis angle below a predetermined value from the first welding position to the final welding position. Select the series of the three-dimensional rotary table three-axis rotation condition operation plan,
3) From the first welding position to the final welding position, the Z-axis angle series satisfying the determination formula cannot be selected and becomes discontinuous, or the Z-axis angle series satisfying the determination formula If the change rate of the Z-axis angle exceeds a predetermined value even if the values are continuous, the allowable width L of the equation (a) is expanded and recalculated from the Z-axis angle classification of 1) above. The welding work apparatus according to claim 5 or 6, wherein an operation plan is performed and the operation plan is executed so that a range of the Z axis that satisfies the determination formula is continuous with respect to the movement of the welding position. The welding work apparatus according to claim 1, wherein the workpiece is a joint pipe composed of a main pipe and a branch pipe joined to a side surface of the main pipe. The welding apparatus according to claim 8, wherein the joint pipe is an aluminum pipe.

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