JPH07214173A - Method for controlling plate material treating robot hand of plate material bending machine - Google Patents

Abstract

PURPOSE:To make the readjusting work unnecessary in the case of executing a trial bending or developing of the variation and to improve the workability and the productivity by detecting the actual dislocation of the shifting direction between a work and a hand during following and controlling the movement of a robot. CONSTITUTION:In the condition of fixing the tip part of a plate material W to a press brake PB by positioning at a back gage, a sensor fitted to the fixed member detects by making the intermediate position of a float member as the reference value. The output value of the sensor at this time is read into a control device as the reference value having no dislocation to the relative distance between the plate material W and the hand H at the time of starting the following movement. When the descent by press-bending starts and the jump-up of the plate material W develops, as the float member approaches the fixed member, the detected value of the sensor is made to be smaller than the reference value, and it is detected that the distance between both members is shortened. At this time, the difference between the calculated detection value and the reference value and the ratio of the variation with time of this calculated value are made as accelerating/decelerating value and the shifting speed of the robot R is decided and started, and the difference between the detected value and the reference value is made to be zero.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate material handling robot which supplies a plate material to a plate material bending machine, for example, a press brake, supports the plate material during processing, and takes out the plate material after processing. Control method.

[0002]

2. Description of the Related Art For example, the operation control of a plate material handling robot for press breaks is performed by stopping the operation of a die on the processing machine side such as supplying a plate material before processing or taking out a plate material after processing. Or, when it is at rest, the control is relatively easy. This is because the processing machine side is not operating, and it is only necessary to avoid the interference between the plate material or the robot hand and the machine side and perform the necessary positioning control.

However, it is not easy to control the robot itself or the robot hand while the plate is supported while the processing machine is operating. During the bending process of the plate material, since the bent portion of the plate material is forcibly clamped by the upper and lower molds and bent, the supporting portion of the plate material by the hand is relative to the deformation of the bending position. This is because the robot and its hand are required to follow the upward or downward displacement of the support portion without delay or position error because the robot and its hand are displaced so as to greatly jump up. If this tracking is insufficient or impossible, the product quality including the product size is deteriorated.

Timing of occurrence and termination of displacement operation such as jumping up of the plate supporting portion during bending, or
The displacing speed, the displacing position, and the displacing posture are different depending on the condition of the plate material, the condition of the mold driving system, or the change thereof, and the condition of the plate material and the condition of the mold driving system are the same. Even if there is, it changes with each bending process. The above-mentioned fluctuation factors include rigidity, plate thickness, shape, fluctuation of elastic deformation (bending) during bending, fluctuation of processing load on press brake, and temperature change of hydraulic drive system on the machine side on the plate side. There are movement fluctuations due to.

In the bending process of the plate material, various factors affect each other in various ways as described above, and when the plate material is bent, the displacement operation such as the jumping up of the supporting portion of the plate material becomes apparent. Therefore, it is not easy to make the robot hand follow the displacement operation of such a support portion faithfully, but as a method conventionally proposed as being capable of following the displacement operation of the plate material support portion as described above. , (A) A method for performing strict control in consideration of fluctuations, (b) A control method for adjusting the actual position of the plate material and the position of the support part that deviates from that position so as to be within the allowable range, (c) of the plate material The actual displacement is
A method has been proposed in which the displacement amount of another portion is substituted for detection, and the position of the support portion is controlled based on the detection amount.

Of the above control methods, the method (a) requires an advanced control technique such as neural control, fuzzy control, AI control, etc., and therefore is still insufficient and has not reached a practical level. In addition, in the method of (b), trial bending of the plate material is performed in advance, and the operating conditions of the robot and the hand are programmed based on the conditions judged to be optimal based on this, and each time a position shift occurs, readjustment is performed. In this method, it is indispensable to stop or interrupt the processing for readjustment or to perform trial bending, which takes time and effort for the plate material or trial bending.

Further, in the method (c), as an example,
There is a method of indirectly estimating the bouncing motion of a plate material by detecting the movement of the die and controlling the robot based on the estimated motion. This method allows the robot to control the movement to some extent in response to fluctuations on the press brake side, but it does not affect the average movement including the mold part that is not in direct contact with the plate material. Since it is detected from the side,
Strictly speaking, it does not mean that the movement of the mold at the bending position is detected.

Further, in the above method (c), in consideration of the elastic deformation of the plate material during the bending process and the variation in the distribution of the bending angle of the plate material before and after the mold, the movement of the plate material at the supporting position is always accurate. I can't figure it out. As a result, the adjustment in the middle of processing is required to some extent as in the method (b).

On the other hand, there is a method proposed by Japanese Patent Laid-Open No. 60-104678 as a control method which is slightly different from the above control methods. This method detects the amount of movement toward the bending center side of the part supporting the plate material during bending,
Since it detects the displacement of the plate material support hand and the plate material to detect the motion of the plate material directly, it may be possible to control with better followability than the previous control method, but in reality,
If a displacement occurs during processing, the plate material is constrained by the supporting hand regardless of whether the plate material is delayed or advanced with respect to the plate material support portion of the hand, so that elastic deformation of the plate material is forced to occur. As a result, there is a practical problem that the plate material moves away from the detector toward the bending center side, and it is not possible to accurately grasp the deviation occurrence state.

[0010]

SUMMARY OF THE INVENTION In view of the present situation of control of a robot hand that supports a plate material in the above-described plate material bending process, the present invention eliminates the positional displacement between the hand supporting the plate material and the plate material during the bending process. Provided is a control method capable of detecting the displacement and controlling the operation speed of the robot so that the deviation value falls within a predetermined value, thereby causing the hand to follow the displacement of the hand supporting portion of the plate material during processing. This is an issue.

[0011]

The constitution of the control method of the present invention made for the purpose of solving the above-mentioned problems is such that during bending, the plate material is supported by the supporting hand in a direction orthogonal to the surface of the plate material, or It is supported in a floating state in which it is allowed to displace within a required range in the orthogonal direction and the plane direction, and when the plate member is floatingly supported by the hand, the relative distance between the plate member and the supporting hand is detected by the detection means. Always detected, the reference value for the relative distance between the plate and the supporting hand is set in advance including the allowable value for the reference value, the detected relative distance is compared with the reference value, and the comparison is made. By controlling the operation direction and the speed of the supporting hand so that the calculated value matches with the reference value or falls within the allowable value, the supporting hand is supported during the bending process. Be made to follow the supporting hand to the displacement movement of the sheet material are those characterized by.

[0012]

When the plate is supported by the supporting hand in a floating state where it is allowed to displace within a predetermined range and is bent, the relative distance between the hand and the plate is constantly detected,
Comparing this detected distance with a reference value that allows displacement of a preset plate material, and controlling the operation of the supporting hand so that the relative distance falls within the reference value or its allowable range based on the result of this comparison. This allows the hand to faithfully follow the displacement operation of the plate material during bending.

[0013]

EXAMPLES Next, examples of the method of the present invention will be described. FIG. 1 is a side view showing an example of a state of bending a plate material using a plate material handling robot having a supporting hand controlled by the present method, and FIG. 2 is a plate material supporting hand to which the method of the present invention is applied. Front view with a part in section,
3 is a front sectional view of an essential part of an example of the operating state of the supporting hand of FIG. 2, FIG. 4 is a front sectional view showing an essential part of another example of the operating state of the supporting hand of FIG. 2, and FIG. 5 is a supporting hand. It is a side view of the principal part of another example of.

In FIG. 1, R is an example of a plate material handling robot, in which a robot body in which arms A1 to A7 are connected via rotary shafts S2 to S6 has a rotary shaft S1 on a machine base MB. It is mounted via. In FIG. 1, PB is a press brake of an example of a bending machine, P and D are upper and lower molds, and F.
Is the frame of the press brake PB.

H is perpendicular to the axis of the arm A8 of the robot R, which is formed by extending the arm A7 of the robot R.
Moreover, this hand H is a supporting hand attached via the seventh rotation axis S7 parallel to the surface of the supporting plate W, and this hand H is formed in the structure illustrated in FIGS. 2 and 3. 2, outlined with FIG.

First, in FIG. 2, 1 and 2 are the arms.
A bracket for connecting the tip of the A8 and the fixing member 3 which is the base of the supporting hand H, and is a member having a substantially U-shaped section or an L-shaped section, respectively, and the tip of the arm A8 and the fixing member. 3 is fixed to the upper surface of the bracket 3, the brackets 1 and 2 are joined to each other, and the joint portion of the brackets 1 and 2 is integrated with the rotary shaft S7.
Are linked by. Since the rotating shaft S7 is connected to the motor M having the speed reducer G, rotation is given from the motor M, whereby the fixing member 3 can be rotated around the shaft S7.

The fixing member 3 is, for example, in the form of a flat rectangular plate, is arranged radially from the center of its bottom face to the four corners, and has four cylinders 4 oriented parallel to the surface of the fixing member 3. It is equipped with. In FIG. 2, only two of the four cylinders 4 are shown. That is, the four cylinders 4 are attached to the center boss 3a formed downward at the center of the lower surface of the fixing member 3, and each rod 4a is fixed to the fixing member 3.
It is provided in a posture that allows it to move forward and backward toward the outer peripheral side. 4b
Is a contact portion formed by a spherical surface such as a ball provided at the tip of the rod 4a, and 3b is a support bracket for the rod 4a.

In addition to the fixing member 3 having the above-mentioned structure, the float member 5 in the shape of a shallow box frame having a shape capable of accommodating the fixing member 3 is arranged, and is the inner surface of the side wall of the float member 5. The receiving portions 6 formed in the concave portions having a conical cross section are provided at the portions of the tips of the rods 4a of the respective cylinders 4 facing the respective abutting portions 4b. Therefore, in the float member 5, the rods 4a of the four cylinders 4 are advanced by the same amount, and the abutting portions 4b of the tips abut the bottoms (the apexes of the conical recesses) 6a of the receiving portions 6. When the plate material W
In the plane parallel to the surface of the fixed member 3, the fixing member 3 is joined while being positioned and held in a fixed position.

Since the float member 5 is supported by the fixed member 3 in a certain range in the direction orthogonal to the surface of the plate W during bending, that is, the float member 5 is displaceably supported, so that the structure shown in FIG. Is added, so this point will be described next.

That is, the fixing member 3 and the floating member 5 are arranged so that their floats are in the direction orthogonal to the plane of the supporting plate W.
The member 5 is fixed to the fixed member 3 or is floatingly supported and displaced in a predetermined range. Therefore, a plurality of two sets of cylinders 7 and 8 are installed between the members 3 and 5. Then, both members 3 and 5 are connected. Although not shown, each of the cylinders 7 and 8 is arranged on the outer periphery of the fixed member 3 at equal intervals, four cylinders each.

Of the two sets of cylinders 7, 8, one set of cylinders 7 is provided with two plate-shaped or flange-shaped support members 7b, 7c on the tip side of its rod 7a. The float member 5 is supported between the two support members 7b and 7c with the annular supported portion 5b formed on the bottom plate 5a sandwiched therebetween. Reference numeral 7d is a contact portion formed by a spherical surface such as a ball provided on the upper surface of the support member 7c.

On the other hand, the other set of cylinders 8 has a rod 8a.
A block-shaped or piece-shaped support member 8b is provided on the tip end side of the so that the tip end surface faces a spherical contact portion 5c such as a ball provided on the upper surface of the bottom plate 5a of the float member 5. It is provided in. Reference numeral 8c is a concave contact surface formed on the front surface of the support member.

In the state shown in FIG. 3, the two sets of cylinders 7 and 8 have a support force of the cylinder 7 in the backward direction of the rod 7a and a support force of the cylinder 8 in the advance direction of the rod 8a. Thus, the support members 7c and 8b at the tip of each rod 7a and 8a support the bottom plate 5a of the float member 5 from the upper and lower surfaces thereof.

In order to support the cylinders 7 and 8, the rod 4a of the horizontal cylinder 4 shown in FIG. 2 is advanced, and the abutting portion 4b at the tip thereof is brought into contact with the bottom 6a of the receiving portion 6. When realized in the closed state, the floating member 5 becomes the fixing member 3
On the other hand, it is constrained and fixed in that position both in the direction parallel to the surface of the plate material W and in the direction orthogonal thereto. Actually, since the air in each cylinder is compressible, even when the position is fixed, the float member 5 is displaced to some extent when receiving an external force.

FIG. 4 shows the rod 8a of the other set of cylinders 8.
Is an example of a state in which the float member 5 is floated and supported by the supporting force of the rod retreating side of one of the assembly cylinders 7 by retracting. When the plate member W is supported on the lower side of the float member 5, the float member 5 is floatingly supported so as to be displaceable in the vertical direction.
The rod 4a is placed in the retracted position, the cylinder 8 is retracted, and is supported by the supporting force of the cylinder 7 on the rod retracted side. Further, the support hand H is turned over 180 degrees from the state of FIG. 3, and when the plate material W is positioned and supported on the upper side of the float member 5, it is supported by the supporting force of the rod advancing side of the cylinder 7. .

The float member 5, which is connected and supported to the fixed member 3 in the fixed state or the floating state by the above-mentioned support structure, has an adsorption pad as an example.
Material supporting frames 9 provided with 10 on the lower surface side are detachably attached to supporting brackets 5b provided on the four corners on the upper surface side of the float member 5, and the plate material W is attached by the pads 10.
Is formed so as to be supported by the support hand H.

In the plate member supporting hand H having the above-mentioned structure, when the plate member W is supported in the floating state of FIG. 4 as an example, the supporting force of the rod 7a of the cylinder 7 is It is adjusted in advance so as to be balanced with the total load of the support frame 9 including the plate material W, the float member 5, and the pad 10. In such a state, when the portion of the plate material W that supports the plate material W being bent is displaced from the position indicated by the broken line in FIG. 1 in the direction and the movement amount indicated by the solid line, it is supported. The supporting hand H is the plate material W.
If the plate member W can be moved in the same direction as the plate member W in perfect synchronization with the displacement, the relative distance between the fixed member 3 of FIG. 4 and the floating member 5 supported by the floating member 3 will not change.

However, actually, as described above, due to various factors, the hand H and the plate material W supported by the hand H are relatively delayed or advanced in mutual displacement, and as a result, During the bending process, the plate material W being clamped in the dies P and D, or the plate material W in the clamped state is bent, such as excessive bending, or a phenomenon such as a plunge or a tension with respect to the die. A phenomenon occurs that adversely affects the processing accuracy.

Therefore, in the present invention, floating displacement is allowed between the plate member W supported by the supporting hand H and the fixing member 3 which is the fixed side of the hand, within the range in which the float member 5 is interposed. In this manner, the above inconvenience can be structurally avoided, and further control can be performed to suppress the behavior of the plate W or the hand H that exceeds the allowable range of the floating displacement. This point will be described below.

Thus, as an example in the present invention, first, the float member 5 and the fixing member 3 are attached to the center boss 3a of the fixing member 3.
A distance sensor 11 for detecting the distance is provided so that the distance between both members 3 and 5 can be measured at any time. This sensor
The detection method of 11 may be any method such as light, laser, sound wave, and electro-mechanical gauge. In addition, the sensor 11
May be attached to a place other than the center boss 3a, and further, on the fixed member 3 and the float member 5, as an example, a plane having the tip of the sensor 11 of the center boss 3a as the origin. It is also possible to set coordinates or plane coordinates including a vertical plane orthogonal to this plane, and provide a plurality of sensors (not shown) on the X and Y axes of the coordinates. In addition,
The distance measured by the sensor 11 may be the distance between the fixed member 3 and the plate material W.

Next, as shown in FIG. 1, an example in which the robot hand H grips and follows the plate material W from above will be described. The back edge of the plate W (not shown in the figure)
When the sensor 11 mounted on the fixing member 3 is positioned at the intermediate position of the float member 5, that is, the rod of the cylinder 4 in FIG.
4a equally advanced, and rods 7a of cylinders 7 and 8,
The distance when the float member 5 is fixedly positioned with respect to the fixed member is detected as a reference value. The output value of the sensor 11 at this time is read by a separately provided control device as a reference value with which the relative distance between the plate material W and the hand H when the follow-up operation is started is not displaced. The robot R is programmed in advance with a movement trajectory of the support hand H of the plate W corresponding to the conditions of the plate W and processing conditions such as the dies P and D, and a reference movement speed although the accuracy is low.

The hand H is placed in the floating state immediately before the tracking operation is started. That is, the rod 4a of the cylinder 4 is moved backward so that the contact portion 4b acting as a wedge member for fixing the float member 5 shown in FIG. The rod 8a of is retracted. At this time, the flow shown in FIG.
In the cylinder 7 of the floating mechanism, the floating force is applied to the rod 7a so as to balance the total weight of the plate material W, the float member 5, and the support frame 9, so that the detection value of the sensor 11 is detected. Does not change much. In the present invention, the gain of the controller is adjusted so that the robot R does not move so that the controller does not excessively react to a slight change in the detected value of the sensor 11.

The bending process starts, and the plate material W as shown in FIG.
When the jumping up of the members starts to approach, the float member 5 first approaches the fixed member 3, so that the detection value of the sensor 11 becomes smaller than the reference value, and it is detected that the distance between the members 3 and 5 is shortened. To be done. The moving speed of the robot R is determined as the acceleration / deceleration value with respect to the speed input in advance by calculating the difference between the detected value calculated at this time and the reference value, and the ratio of the time change of the calculated value of this difference. It is activated so that the detected value and the reference value are zero here. The calculation algorithm at this time may be determined in consideration of a certain condition adapted to the tracking operation.

FIG. 3 shows a state in which the detected value is not different from the reference value while the supporting hand H is following the displacement operation of the plate W during bending. Even in this case, if the temporal change rate comparing the detected value and the reference value is relatively large in either direction, acceleration / deceleration is not stopped,
The control amount is determined so that the difference between the detected value and the reference value and the temporal change ratio of this difference become small. FIG. 4 shows a state in which the plate member W tends to be delayed because the moving speed of the supporting hand H of the robot is too fast, and the float member 5 is separated from the fixed member 3. In this case, the support hand H of the robot is controlled so as to decelerate relatively to the plate material W. Here, in order to avoid the hunting phenomenon in control, if the difference between the reference value and the detected value is within a certain range, that is, if it is within the allowable value, the control device may be allowed to react without reacting. good. Further, the displaceable amount of the float member 5 and the size of the detectable distance of the sensor 11 may be determined in consideration of the controllable fluctuation range.

FIG. 5 shows an example of a hand H having a grip 12 composed of a fixed member 12a and a movable member 12b as a means for gripping the plate material W. In FIG. 5, 12c is a box-shaped hand body, 12d is an open / close drive source for the movable member 12b, and this grip 12 closes the movable member 12b when the plate member W is positioned and grips the plate member W for processing. When the moving parts move
12b is opened to follow the bouncing displacement of the plate material W in that state, and when the machining is finished, the movable member 12b is closed and the plate material W that has recoiled and displaced is gripped again in that posture for the next machining or unloading. It is a transition. Therefore, the reference value in this case is the output value of the sensor 11 in the state where the movable member 12b of the grip 12 is opened before the start of the follow-up, and the grip 12 that is opened while the follow-up of the plate material W being processed is followed. By detecting the positional deviation of the plate material W between the two members 12a and 12b, the same control as in the above example is performed.

[0036]

The present invention is as described above,
The following effects can be obtained. First, because the robot movement is controlled by detecting the actual deviation of the movement direction of the work and the hand during tracking, it is necessary to enter the calculated movement trajectory and speed in advance for the robot movement program. No trial bending or readjustment work is required when fluctuations occur, and workability and productivity are significantly improved.

Further, the hand is provided with a sensor for detecting the positional deviation between the plate material and the hand in the direction of the following movement locus, the increase / decrease of the detected value with respect to the reference value is calculated, and the movement speed of the robot hand is controlled, thereby pre-driving. Since the standard work for speed adjustment and speed condition determination is unnecessary, productivity is significantly improved. Furthermore, since the fluctuation of the bouncing motion of the plate material W due to the condition of the plate material or the fluctuation on the processing machine side can be absorbed, the following plate material is not pushed or pulled too much, and the processing quality can be stabilized.

[Brief description of drawings]

FIG. 1 is a side view showing an example of a state of bending a plate material using a plate material handling robot having a supporting hand controlled by the present method.

FIG. 2 is a front view showing a cross section of a part of a supporting hand of a plate material to which the method of the present invention is applied.

3 is a front sectional view of a main part of an example of an operating state of the support hand of FIG.

4 is a front cross-sectional view showing the main parts of another example of the operating state of the support hand of FIG.

FIG. 5 is a side view of a main part of another example of the supporting hand.

[Explanation of symbols]

 1, 2 Bracket 3 Fixing member 4 Cylinder 4a Rod 5 Float member 6 Receiving part 7,8 Cylinder 7b, 7c Supporting member 7a, 8a Rod 9 Plate material supporting frame 10 Pad 11 Sensor W Plate material R Robot H Supporting hand

Claims (1)

[Claims] 1. A plate member is supported by a supporting hand in a floating state in which it is allowed to displace within a required range in a direction orthogonal to the plane of the plate member or in the orthogonal direction and the plane direction during bending. That, when the plate material is floatingly supported by the hand, the relative distance between the plate material and the supporting hand is always detected by the detecting means, and the reference value is the reference value in advance for the relative distance between the plate material and the supporting hand. Is set to include an allowable value for, the detected relative distance is compared and calculated with the reference value, and the operation direction of the supporting hand is such that the comparison calculation value matches the reference value or falls within the allowable value. For a plate bending machine, the supporting hand is made to follow the displacement operation of the plate supported by the supporting hand during bending, by controlling the speed and its speed. Control method for the plate material handling robot hand.