JP6442317B2 - Positioning control method - Google Patents

Description

  The present invention relates to a positioning control method for a feed device provided with two feed mechanisms that intersect in a state where the feed axes are not orthogonal (non-orthogonal state).

  A machine tool such as a lathe has conventionally been provided with two feed mechanisms in which the feed axes intersect in a non-orthogonal state, and a machine configured to create a virtual feed axis by a synchronized feed operation by the two feed mechanisms. There is a machine. A lathe as an example of such a machine tool is shown in FIG. FIG. 9 is a side view of the lathe as viewed from the direction facing the main shaft.

  As shown in FIG. 9, the lathe 100 includes a bed 101, a headstock 102 disposed on the bed 101, a tailstock 104 and a carriage 120, and on the carriage 120 in the direction indicated by the arrow X-axis. A saddle 110 that is movably disposed, similarly, a turret 111 that is movably disposed in the direction of the arrow Y′-axis is provided on the saddle 110.

  The spindle stock 102 rotatably supports the spindle 103, and similarly the tailstock 104 rotatably supports a tailstock shaft 105. The spindle 103 and the tailstock shaft 105 are opposed to each other. Is located on the same axis.

  The carriage 120 is driven by a Z-axis feed mechanism 130 so as to move along a Z-axis direction that is a direction parallel to the axis of the main shaft 103 and perpendicular to the paper surface. The carriage 110 is disposed on the bed 101, and the saddle 110 is driven by an X-axis feed mechanism 125 to move along the X-axis direction which is a feed axis in a direction orthogonal to the Z-axis. 120 is provided.

  The tool post 111 holds the turret 112 rotatably about an axis parallel to the axis of the main shaft 103, is driven by a Y′-axis feed mechanism 115, and is orthogonal to the Z-axis. Further, it is provided on the saddle 110 so as to move along the Y′-axis direction which is a feed axis in a direction intersecting with the X-axis in a non-orthogonal state.

  The Z-axis feed mechanism 130 is provided on the bed 101, guides the movement of the carriage 120 along the Z-axis direction, and a Z-axis servo that is also provided on the bed 101. A motor 131, a Z-axis ball screw (not shown) connected to the Z-axis servo motor 131, and a ball screwed to the Z-axis ball screw (not shown) and fixed to the carriage 120 It consists of a nut (not shown).

  The X-axis feed mechanism 125 is provided on the carriage 120 and guides the movement of the saddle 110 along the X-axis direction, and the X-axis feed mechanism 125 is also provided on the carriage 120. A servo motor 126, an X-axis ball screw (not shown) connected to the X-axis servo motor 126, and a ball nut screwed to the X-axis ball screw (not shown) and fixed to the saddle (Not shown).

  Similarly, the Y′-axis feed mechanism 115 is provided on the saddle 110 and also provided on the saddle 110, and a Y′-axis guide portion 113 that guides the movement of the tool post 111 along the Y′-axis direction. A Y′-axis servo motor 116, a Y′-axis ball screw (not shown) connected to the Y′-axis servo motor 116, a threaded engagement with the Y′-axis ball screw (not shown), and the tool post 111. It is comprised from the ball nut (not shown) etc. which were fixed to.

  The Z-axis servo motor 131 of the Z-axis feed mechanism 130, the X-axis servo motor 126 of the X-axis feed mechanism 125, and the Y′-axis servo motor 116 of the Y′-axis feed mechanism 115 are operated by appropriate control devices, respectively. Be controlled.

  In the lathe 100 having the above configuration, under the control of the control device, the turret 112 has a Z-axis direction along the axis of the main shaft 103, an X-axis direction orthogonal to the Z-axis, and the Z-axis and X-axis. It moves in the Y-axis direction (creating Y-axis direction) perpendicular to both axes.

  That is, the turret 112 moves along the Z-axis when the Z-axis servomotor 131 is driven under the control of the control device, and moves to the X-axis when the X-axis servomotor 126 is driven. Move along.

  Further, under the control of the control device, the X-axis servo motor 126 and the Y′-axis servo motor 116 are driven in synchronization, so that the turret 112 is orthogonal to both the Z-axis and the X-axis. Move along the Y-axis direction. Specifically, the saddle 110 is moved in the X-axis minus direction by the X-axis feed mechanism 125, and at the same time, the tool post 111 is moved in the Y'-axis plus direction by the Y'-axis feed mechanism 115 in synchronization with this. The turret 112 moves in the Y axis plus direction. On the contrary, the saddle 110 moves in the X-axis plus direction by the X-axis feed mechanism 125, and at the same time, the tool post 111 moves in the Y'-axis minus direction by the Y'-axis feed mechanism 115 in synchronization with this. Thus, the turret 112 moves in the Y-axis minus direction.

  Thus, according to the lathe 100, the work is appropriately held on the spindle 103, the tool is appropriately held on the turret 112, and the tool is moved in the XZ plane while the work is rotated. The workpiece can be turned, and the rotation tool held by the turret 112 while the rotation of the workpiece is stopped or the workpiece is slowly rotated, the X axis, the Y axis, and So-called milling can be performed by moving in the three-dimensional space of the Z axis.

  By the way, conventionally, in the field of machine tools, in order to guarantee the good machining accuracy, the positioning accuracy of each feed mechanism constituting the machine tool is compensated. For example, in each feed mechanism, the actual movement position is measured while moving the control object at a predetermined pitch interval, and the error (pitch error) between the command position and the actual movement position of the control object is calculated. When the feed mechanism is driven and controlled, the control position is corrected based on the calculated pitch error. An example of a measuring apparatus that measures the pitch error is described in Patent Document 1 below.

  Of course, such correction is also necessary in the lathe 100 having the above-described configuration. In the lathe 100, conventionally, the X-axis feed mechanism 125, the Y′-axis feed mechanism 115, and the Z-axis feed mechanism 130 are used. For each, the pitch error is measured, and when the X-axis feed mechanism 125, the Y′-axis feed mechanism 115, and the Z-axis feed mechanism 130 are driven and positioned, the respective pitch errors are corrected.

  In this lathe 100, it is necessary to correct the pitch error in the generated Y-axis direction created by the X-axis feed mechanism 125 and the Y′-axis feed mechanism 115. However, this has conventionally been corrected. In addition, it is considered that the pitch error in the generating Y-axis direction is corrected by correcting each pitch error of the Y′-axis feed mechanism 115.

Japanese Patent Application Laid-Open No. 7-100736

  In the lathe 100, as described above, the X-axis feed mechanism 125 using the X-axis as the feed axis and the Y′-axis feed mechanism 115 using the Y′-axis crossing the X-axis as the feed axis are synchronized. Since the Y-axis, which is a virtual feed axis, is created by the feed operation, theoretically, the positioning error in the Y-axis direction includes a plane including the X-axis and the Y′-axis (this plane also includes the Y-axis). Error included due to the straightness of the X-axis and the straightness of the Y′-axis.

  The straightness of the Y ′ axis depends on the Y ′ axis guide portion 113 provided in the saddle 110, but the saddle 110 is disposed on the carriage 120 and has a considerable rigidity. In the end, the straightness of the Y ′ axis is integrated into the machining accuracy of the Y ′ axis guide 113 formed on the saddle 110, and this machining accuracy is sufficiently high. Therefore, as a conclusion, it can be said that the influence of the straightness of the Y′-axis on the positioning error in the generating Y-axis direction is extremely small.

  On the other hand, the carriage 120 on which the X-axis feed mechanism 125 is provided is generally provided in an overhanging state from the bed 101 as shown in FIG. 9, and this carriage 120 depends on the position of the saddle 110. Therefore, the straightness of the X axis in the XY ′ plane is worse than the straightness of the Y ′ axis and greatly affects the pitch error of the generating Y axis.

  In order to avoid such a problem, it is conceivable that both ends of the carriage 120 are supported so that the carriage 120 does not overhang from the bed 101. When the carriage 120 is located in the middle portion, the carriage 120 is elastically deformed into a concave shape, so that the straightness of the X axis cannot be improved after all.

  Thus, in the lathe 100, a positioning error in the generating Y-axis direction due to the straightness of the X-axis in the XY ′ plane is generated. Conventionally, with respect to such a positioning error in the generating Y-axis direction, This is not corrected, and therefore the positioning accuracy in the direction of the generating Y-axis is not necessarily sufficient.

  The present invention has been made in view of the above circumstances, and includes two feed mechanisms in which the feed axes intersect with each other in a non-orthogonal state, and a virtual feed shaft is obtained by a synchronized feed operation by the two feed mechanisms. It is an object of the present invention to provide a positioning control method capable of performing positioning in the virtual feed axis direction with high accuracy in the feeding device configured to create the above.

The present invention for solving the above-mentioned problems has a first feed shaft that has a first feed shaft and moves a moving body along the first feed shaft, and intersects the first feed shaft in a non-orthogonal state. Control of the operation of the first feed mechanism and the second feed mechanism of a feed device having a second feed shaft and a second feed mechanism that moves the first feed mechanism along the second feed shaft Control method,
According to positioning data set for each of the first feed axis and the second feed axis, the first feed mechanism and the second feed mechanism are simultaneously operated to make the movable body a virtual feed axis that is orthogonal to the second feed axis. In a positioning control method for positioning in a direction,
After acquiring in advance the positioning accuracy of the moving body in the virtual feed axis direction,
Based on the obtained positioning accuracy in the direction of the virtual feed axis, the straightness in the plane including the second feed axis and the virtual feed axis is estimated in advance for the second feed axis of the second feed mechanism. ,
When positioning the first feed mechanism and the second feed mechanism according to the positioning data to move the moving body in the virtual feed axis direction, the estimated second feed mechanism in the second feed axis direction is used. A correction amount for compensating for the positioning error amount along the first feed axis of the first feed mechanism and the positioning error amount along the second feed axis of the second feed mechanism, obtained based on the straightness, is calculated. The positioning control method corrects each positioning data according to the calculated correction amount.

  According to the present invention, first, according to the positioning data set for the first feed shaft and the second feed shaft, the first feed mechanism and the second feed mechanism are simultaneously operated to move the moving body to the virtual feed. The moving body is moved in the axial direction, and the positioning accuracy of the movable body in the virtual feed axis direction is obtained using an appropriate measuring device such as a laser measuring device. Note that the positioning accuracy in the virtual feed axis direction is a standard evaluation accuracy in order to evaluate the performance of the feed device.

  Next, based on the positioning accuracy in the virtual feed axis direction acquired as described above, the second feed axis of the second feed mechanism is within a plane including the second feed axis and the virtual feed axis. Estimate the straightness of.

  As described above, the positioning error in the virtual feed axis direction is theoretically the straightness of the second feed axis in the plane including the second feed axis and the virtual feed axis (this plane also includes the first axis). And errors due to the straightness of the first feed axis are included, but the influence of the straightness of the first feed axis on the positioning accuracy in the virtual feed axis direction is negligible. The positioning accuracy greatly depends on the straightness of the second feed shaft.

  Therefore, the positioning accuracy in the virtual feed axis direction, which is executed by operating the first feed mechanism and the second feed mechanism, can be considered as straightness in the second feed axis is expressed as it is. From the positioning accuracy in the virtual feed axis direction, the straightness of the second feed mechanism with respect to the second feed axis can be estimated.

  When the positioning control of the first feed mechanism and the second feed mechanism is performed according to the positioning data in order to move the moving body in the virtual feed axis direction, the estimated second feed axis of the second feed mechanism Based on the straightness of the direction, the amount of positioning error along the first feed axis of the first feed mechanism and the amount of correction to compensate for the amount of positioning error along the second feed axis of the second feed mechanism are calculated. Thus, each positioning data is corrected according to the calculated correction amount. Thereby, the positioning error in the virtual feed axis direction is corrected.

  That is, the positioning in the virtual feed axis direction is realized by a combined operation of the positioning operation in the first feed axis direction of the first feed mechanism and the positioning operation in the second feed axis direction of the second feed mechanism. In order to correct the positioning error in the virtual feed axis direction, it is necessary to perform correction in the first feed axis direction and correction in the second feed axis direction in accordance with the error, and by performing such correction, The positioning error in the virtual feed axis direction is compensated.

  As described above, according to the positioning control method according to the present invention, it is possible to compensate for the positioning error in the virtual feed axis direction which has not been realized in the past, so that the positioning accuracy in the virtual feed axis direction is highly accurate. can do.

  In the present invention, the correction amount for compensating the positioning error along the first feed axis of the first feed mechanism is set to the correction amount for compensating the pitch error along the first feed axis of the first feed mechanism. In addition, the correction amount for compensating for the positioning error along the second feed axis of the second feed mechanism includes the correction amount for compensating for the pitch error along the second feed axis of the second feed mechanism. Also good.

  Conventionally, generally, a pitch error in the first feed shaft of the first feed mechanism and a pitch error in the second feed shaft of the second feed mechanism are measured in advance, and the positioning operation of the first feed mechanism is performed. In the positioning operation of the second feed mechanism, each pitch error is corrected. Therefore, when the positioning in the virtual feed axis direction is performed by the combined operation of the positioning operation in the first feed axis direction of the first feed mechanism and the positioning operation in the second feed axis direction of the second feed mechanism. When the first feed mechanism is positioned in the first feed axis direction, the pitch error is corrected, and when the second feed mechanism is positioned in the second feed axis direction, the pitch error is corrected. Positioning in the virtual feed axis direction can be made with higher accuracy.

  Further, in the present invention, a correction amount for compensating a backlash error along the first feed shaft of the first feed mechanism is added to a correction amount for compensating the positioning error amount along the first feed shaft of the first feed mechanism. In addition, the correction amount for compensating for the positioning error along the second feed axis of the second feed mechanism includes the correction amount for compensating for the backlash error along the second feed axis of the second feed mechanism. Also good.

  Conventionally, backlash correction is generally performed in addition to the pitch error correction. Therefore, when positioning in the virtual feed axis direction, backlash correction is performed when the first feed mechanism is positioned in the first feed axis direction, and backlash correction is performed when the second feed mechanism is positioned in the second feed axis direction. As a result, the positioning in the virtual feed axis direction can be made with higher accuracy. The backlash correction reverses the amount of backlash that occurs when the feed direction along the first feed axis of the first feed mechanism is reversed and the feed direction along the second feed axis of the second feed mechanism. Executed by measuring the amount of backlash that occurs in advance and correcting the amount of backlash when reversing the feed direction of the first feed mechanism and when reversing the feed direction of the second feed mechanism. Is done.

  As described above, according to the positioning control method of the present invention, it is possible to compensate for a positioning error in the virtual feed axis direction, which has not been realized in the past, so that the positioning accuracy in the virtual feed axis direction is highly accurate. Can be.

It is the block diagram which showed the control apparatus for implementing the control method which concerns on one Embodiment of this invention. It is explanatory drawing which showed the data table which concerns on the correction amount of the X-axis stored in the correction data memory | storage part which concerns on this embodiment. It is explanatory drawing which showed the data table which concerns on the correction amount of the Y 'axis | shaft stored in the correction data storage part which concerns on this embodiment. It is explanatory drawing which showed the data table which concerns on the correction amount of Z axis | shaft stored in the correction data memory | storage part which concerns on this embodiment. It is a graph which shows the positioning error of the creation Y-axis measured in the state which does not correct | amend the error which concerns on the straightness of a X-axis direction. It is a graph which shows the positioning error of the creation Y-axis measured in the state which correct | amended the error which concerns on the straightness of a X-axis direction. It is a diagram which shows the circular interpolation accuracy in the XY plane measured in the state which does not correct | amend the error which concerns on the straightness of a X-axis direction. It is a diagram which shows the circular interpolation accuracy in the XY plane measured in the state which correct | amended the error which concerns on the straightness of a X-axis direction. It is the side view which showed the lathe of the structure which can create the Y-axis which is a virtual feed axis.

  Hereinafter, a positioning control method according to a specific embodiment of the present invention will be described with reference to the drawings. Note that the positioning control method of this example is a method of controlling the lathe 100 shown in FIG. 9 and is executed by the control device 1 shown in FIG.

A. Regarding Configuration of Control Device First, the configuration of the control device 1 of this example will be described. As shown in FIG. 1, the control device 1 of this example includes an NC program storage unit 2, a program analysis unit 3, a position command unit 4, a position correction unit 6, a correction data storage unit 5, an X-axis position control unit 10, Axis speed controller 11, X-axis current controller 12, Y'-axis position controller 15, Y'-axis speed controller 16, Y'-axis current controller 17, Z-axis position controller 20, Z-axis speed controller 21 And a Z-axis current control unit 22. FIG. 1 shows only main components for controlling the X-axis servo motor 126, the Y′-axis servo motor 116, and the Z-axis servo motor 131.

  The NC program storage unit 2 is a functional unit that stores an NC program, and the NC program is input from the outside, for example. The program analysis unit 3 is a functional unit that reads and executes the NC program stored in the NC program storage unit 2, analyzes the read NC program, and supplies each feed axis (X axis, generating Y axis). And the movement position and the feed speed with respect to the Z axis) are recognized and transmitted to the position command unit 4.

  The position command unit 4 generates a position command for each feed axis on the basis of the movement position and feed speed for each feed axis received from the program analysis unit 3, and each of the generated position commands is set to the X-axis position. The data is transmitted to the control unit 10, the Y′-axis position control unit 15, and the Z-axis position control unit 20.

  For example, when the position command unit 4 receives a command related to the movement position and the feed speed related to the X axis, the position command unit 4 generates an X axis position command corresponding to the command and transmits it to the X axis position control unit 10. When a command related to the movement position and the feed speed is received, a Z-axis position command corresponding to the command is generated and transmitted to the Z-axis position control unit 20. Further, when a command related to the movement position and feed speed relating to the generating Y axis is received, the generating Y axis is generated by a synchronized feeding operation of the X axis feeding mechanism 125 and the Y ′ axis feeding mechanism 115. The position command unit 4 generates an X-axis position command and a Y′-axis position command according to the reception command, transmits the X-axis position command to the X-axis position control unit 10, and transmits the Y′-axis position command. A position command is transmitted to the Y′-axis position control unit 15.

  Then, the X-axis position control unit 10 that has received the position command generates a speed command in accordance with the received position command and transmits it to the X-axis speed control unit 11, and the X-axis speed control unit 11 receives the current according to the received speed command. A command is generated and transmitted to the X-axis current control unit 12, and the X-axis current control unit 12 generates a drive current according to the received current command and supplies it to the X-axis servo motor 126.

  Similarly, the Y′-axis position control unit 15 generates a speed command according to the received position command and transmits it to the Y′-axis speed control unit 16, and the Y′-axis speed control unit 16 performs a current command according to the received speed command. Is transmitted to the Y′-axis current control unit 17, and the Y′-axis current control unit 17 generates a drive current according to the received current command and supplies it to the Y′-axis servo motor 116.

  The Z-axis position control unit 20 generates a speed command according to the received position command and transmits it to the Z-axis speed control unit 21. The Z-axis speed control unit 21 generates a current command according to the received speed command. The Z-axis current control unit 22 generates a drive current according to the received current command and supplies the drive current to the Z-axis servo motor 131.

  Thus, the X-axis servo motor 126 is driven by the drive current supplied from the X-axis current control unit 12, and the Y′-axis servo motor 116 is driven by the drive current supplied from the Y′-axis current control unit 17. The Z-axis servomotor 131 is driven by a drive current supplied from the Z-axis current control unit 22. The X-axis servo motor 126, the Y′-axis servo motor 116, and the Z-axis servo motor 131 are each provided with a rotary encoder, and the actual position data detected by each rotary encoder corresponds to the corresponding position command. Provide feedback.

  The correction data storage unit 5 includes a position correction amount including a correction amount for compensating for a pitch error, etc. corresponding to each position of the X axis, Y ′ axis, and Z axis, and the X axis, Y ′ axis, and Z axis. This is a functional unit that stores the backlash correction amount in the axis, and stores these position correction amount and backlash correction amount input from the outside.

  The position correction unit 6 receives the position command generated by the position command unit 4 from the position command unit 4, reads the correction amount for the received position command from the correction data storage unit 5, and outputs the X-axis This is a processing unit that performs processing to be added to each position command input to the position control unit 10, the Y′-axis position control unit 15, and the Z-axis position control unit 20.

B. Next, the positioning control method of this example executed by the control device 1 having the above configuration will be described.

  First, the positioning accuracy (including pitch error) and backlash amount of the X-axis feed mechanism 125 in the X-axis direction, the positioning accuracy (including pitch error) and backlash amount of the Y′-axis feed mechanism 115 in the Y′-axis, and the Z Measure the positioning accuracy (including pitch error) and backlash amount of the axis feed mechanism 130 in the Z-axis direction, and make corrections necessary to compensate for this based on the measured pitch error and backlash error amount. The amount is calculated and stored in the correction data storage unit 5.

  The positioning accuracy and backlash amount can be measured using, for example, a laser length measuring device, but may be measured using other devices. The laser length measuring device is composed of, for example, a laser head and a reflecting mirror, and the laser head includes a laser oscillator that irradiates laser light, a light receiving element that receives the laser light, and a laser interferometer provided in front of the light receiving element. Composed. In this laser length measuring device, a laser beam is emitted from a laser oscillator toward a reflecting mirror, reflected by the reflecting mirror, and laser light that has passed through the laser interferometer is received by the light receiving element, thereby receiving the reflecting mirror and the light receiving device. The distance between the elements is measured.

  When measuring the positioning accuracy and the like of the X-axis feed mechanism 125 using this laser length measuring device, specifically, first, a laser head is attached to the turret 112, and the X-axis is moved from the laser head to the X-axis. A laser beam is irradiated along the laser beam and a reflecting mirror is installed in front of the laser beam irradiation direction so that the laser beam reflected by the reflecting mirror is received by the laser head. Then, the X-axis servo motor is driven to control the turret 112 to move in the X-axis direction, for example, at a pitch of 1 mm, and the actual moving distance is measured by the laser length measuring device. Measure the pitch error. Further, the backlash amount is calculated from a positioning error when the moving direction of the turret 112 along the X axis is reversed.

  The same applies to the Y′-axis feed mechanism 115 and the Z-axis feed mechanism 130. Similarly to the X-axis feed mechanism 125 described above, the pitch error amount and backlash amount of the Y′-axis feed mechanism 115, and the Z-axis feed mechanism. A pitch error amount and a backlash amount of 130 are calculated.

  Further, in this example, the positioning accuracy in the generating Y-axis direction is measured in the same manner. That is, first, the laser head is attached to the turret 112 so that laser light is emitted from the laser head along the generating Y axis, and a reflecting mirror is installed in front of the irradiation direction of the laser light, The laser light reflected by the reflecting mirror is received by the laser head.

  The X-axis feed mechanism 125 and the Y′-axis feed mechanism 115 are simultaneously driven and controlled to move the turret 112 in the direction of the generating Y axis, for example, at a pitch of 1 mm, and the actual moving distance is measured by the laser length measuring device. Then, the positioning error in the creation Y-axis direction is calculated. Note that the position of the turret 112 in the X-axis direction is controlled to be appropriately maintained.

  Next, the pitch error amount and backlash amount in the X-axis direction related to the X-axis feed mechanism 125 measured as described above, the pitch error amount and backlash amount in the Y′-axis direction related to the Y′-axis feed mechanism 115, and Based on the pitch error amount and backlash amount related to the Z-axis feed mechanism 130, correction amounts for compensating them, that is, the pitch error correction amount and backlash correction amount in the X-axis direction, and the pitch error correction amount in the Y′-axis direction The backlash correction amount, the pitch error correction amount in the Z-axis direction, and the backlash correction amount are calculated.

  Further, based on the measured positioning error in the Y-axis direction, the straightness along the X-axis direction of the X-axis feed mechanism 125 in the XY plane is estimated, and the estimated straightness is based on the estimated straightness. Then, a correction amount for compensating the error is calculated.

  As described above, it can be said that the positioning error in the generating Y-axis direction is substantially equal to the straightness along the X-axis direction of the X-axis feed mechanism 125 in the XY plane. Accordingly, the straightness along the X-axis direction of the X-axis feed mechanism 125 in the XY plane can be estimated from the positioning error of the generating Y-axis. This point will be described in some detail. FIG. 5 is a graph showing the positioning error of the generating Y axis measured without correction. The horizontal axis is the position in the generating Y axis direction, and the vertical axis is the positioning error amount. The position in the generated Y-axis direction corresponding to the horizontal axis is represented by the position in the X-axis direction in the X-axis feed mechanism 125 and the position in the Y′-axis direction in the Y′-axis feed mechanism 115 by nature. Therefore, by taking the correspondence between the position in the X-axis direction corresponding to each position of the created Y-axis and the positioning error, the straightness along the X-axis direction of the X-axis feed mechanism 125 is expressed. By performing the processing, the straightness can be estimated.

  In this example, based on the straightness along the X-axis direction of the X-axis feed mechanism 125 estimated in this way, the correction amount in the X-axis direction and the Y′-axis direction to compensate for the error Is calculated for each position where the pitch error correction amount is calculated for the X axis. That is, the correction amount for compensating the error in the Y-axis direction is distributed to the component (correction amount) in the X-axis direction and the component (correction amount) in the Y′-axis direction. A correction amount in the X-axis direction and a correction amount in the Y′-axis direction are calculated. If there is no actual data, it is calculated by interpolation processing.

  Then, the position correction amount and backlash correction amount at each position of 1 mm pitch interval in the X-axis direction, the position correction amount and backlash correction amount at each position of 1 mm pitch interval in the Y′-axis direction calculated as described above. , And the position correction amount and the backlash correction amount at each position at 1 mm pitch intervals in the Z-axis direction are stored in the correction data storage unit 5.

  The position correction amount at each position in the X-axis direction is obtained by adding the pitch error correction amount in the X-axis direction and the correction amount for compensating for the straightness of the X-axis, and then adding this to the correction data storage unit 5. Store in. FIG. 2 shows a data table related to the X-axis position correction amount stored in the correction data storage unit 5 in this way, and the X-axis correction amount in the table corrects the straightness of the X-axis. The correction amount and the pitch error correction amount are added together, and the Y′-axis correction amount is a correction amount for correcting the straightness of the X-axis.

  3 shows a data table relating to the Y′-axis position correction amount (pitch error correction amount), which is also stored in the correction data storage unit 5, and FIG. 4 similarly shows the correction data storage unit 5 3 shows a data table relating to the Z axis position correction amount (pitch error correction amount) stored in the table.

  Thus, as described above, after the position correction amount and the backlash correction amount related to the X axis, the Y ′ axis, and the Z axis are stored in the correction data storage unit 5, under the control of the control device 1, A lathe 100 is controlled.

  For example, when performing machining in accordance with the NC program stored in the NC program storage unit 2, first, the program analysis unit 3 appropriately reads the NC program from the NC program storage unit 2, and the read NC program is the program. A command such as a movement position and a feed speed, which is analyzed by the analysis unit 3 and related to each feed axis (X axis, generation Y axis and Z axis) is recognized, and a command such as the recognized movement position and feed speed is received as a position command unit. 4 is transmitted.

  When a command related to the movement position and feed speed for each feed axis is transmitted from the program analysis unit 3 to the position command unit 4, the position command unit 4 sequentially generates a position command for the corresponding feed axis, The data is transmitted to the position correction unit 6 and the corresponding X-axis position control unit 10, Y′-axis position control unit 15, and Z-axis position control unit 20.

  For example, when a position command in the X-axis direction is generated in the position command unit 4 and the generated position command is transmitted to the position correction unit 6 and the X-axis position control unit 10, the position correction unit 6 The X-axis correction amount and the Y′-axis correction amount corresponding to the position are read from the correction data storage unit 5, and the read X-axis correction amount is used as a position command input to the X-axis position control unit 10. At the same time, the Y′-axis correction amount is input to the Y′-axis position controller 15. Thus, the X-axis pitch error and straightness are corrected by such correction.

  In addition, when the position command unit 4 generates position commands related to the X-axis direction and the Y′-axis direction for movement in the generating Y-axis direction, the generated position command related to the X-axis direction is A position command in the Y′-axis direction is transmitted to the position correction unit 6 and the Y′-axis position control unit 15 while being transmitted to the position correction unit 6 and the X-axis position control unit 10. Then, the position correction unit 6 reads the X-axis correction amount and the Y′-axis correction amount at the position corresponding to the input position command in the X-axis direction from the correction data storage unit 5, and reads the read X-axis correction amount. In addition to the position command input to the X-axis position control unit 10, the Y′-axis correction amount is added to the position command input to the Y′-axis position control unit 15, and the input position command in the Y′-axis direction The Y′-axis correction amount at the position corresponding to the position is read from the correction data storage unit 5 and added to the position command input to the Y′-axis position control unit 15. Thus, the correction corrects the pitch error and straightness of the X-axis, and corrects the pitch error of the Y′-axis.

  Further, when a position command in the Z-axis direction is generated in the position command unit 4 and the generated position command is transmitted to the position correction unit 6 and the Z-axis position control unit 20, the position correction unit 6 The Z-axis correction amount corresponding to the position is read from the correction data storage unit 5, and the read Z-axis correction amount is added to the position command input to the Z-axis position control unit 20. Thus, the Z-axis pitch error is corrected by such correction.

  In the NC program, when the movement in the X-axis direction and the Z-axis direction are instructed simultaneously, or when the movement in the X-axis direction and the movement in the generating Y-axis direction are instructed simultaneously, the position command unit 4 The position correction unit 6 executes a process that combines the above-described processes.

  Further, when the correction amount corresponding to the position command input from the position command unit 4 is not stored in the correction data storage unit 5, the position correction unit 6 stores the data stored in the correction data storage unit 5. Based on this, a correction amount corresponding to the position command is calculated by interpolation processing, and the calculated correction amount is input to the X-axis position control unit 10, the Y′-axis position control unit 15, and the Z-axis position control unit 20 The process of adding to the corresponding one is performed.

  When the position command input from the position command unit 4 reverses the moving direction, the position correction unit 6 receives the backlash correction amount of the corresponding axis from the correction data storage unit 5. Is read, and the read backlash correction amount is added to the corresponding position command input to the X-axis position control unit 10, the Y′-axis position control unit 15, and the Z-axis position control unit 20. Thus, backlash in each axis is corrected by such correction.

  As described above in detail, according to this example, when the X-axis feed mechanism 125 is positioned in the X-axis direction, the turret 112 is positioned in the X-axis direction. , The positioning error due to the straightness in the XY plane is corrected, so that the turret 112 including the straightness is positioned in the X-axis direction, and the generated Y-axis is compared to the conventional case. Positioning in the direction can be performed with high accuracy.

  In addition, since the pitch error and backlash correction are performed for each of the X axis, the Y ′ axis, and the Z axis, the positioning accuracy for each feed axis can be made higher. The positioning in the generating Y-axis direction can also be performed with high accuracy.

  FIG. 6 shows that the X-axis servo motor 126 and the Y′-axis servo motor 116 are driven by the control device 1 in order to move the turret 112 in the direction of the generating Y-axis with the X-axis position fixed at an appropriate position. , Control to measure the positioning accuracy in the generating Y-axis direction. As can be seen by comparing FIG. 6 with FIG. 5 described above, according to the positioning control method of this example in which the error relating to the straightness in the X-axis direction in the XY plane is corrected. Positioning accuracy in the Y-axis direction can be improved, and positioning in the generating Y-axis direction can be performed with high accuracy.

  FIG. 7 is a diagram showing the result of measuring the circular interpolation accuracy (roundness) in the XY plane when the error relating to the straightness in the X-axis direction is not corrected, and FIG. It is a diagram which shows the result of having measured the circular-arc interpolation precision (roundness) in XY plane at the time of correct | amending the error which concerns on the straightness of a X-axis direction according to the positioning control method of an example. The circular interpolation accuracy was measured by a so-called double ball bar (DBB) method. 7 and 8, the radius of the reference circle is 20 μm, and one scale in the diagrams is 2 μm.

  As shown in FIG. 7, the diagram relating to the circular interpolation accuracy when the error related to the straightness in the X-axis direction is not corrected is greatly distorted, and the circular interpolation accuracy is not good, but it is shown in FIG. As described above, by correcting the error related to the straightness in the X-axis direction, the diagram related to the circular interpolation accuracy becomes close to a perfect circle, and the circular interpolation accuracy is improved.

  As described above, according to the control device 1 and the positioning control method of this example, the positioning error due to the straightness in the XY plane along the X-axis direction of the X-axis feed mechanism 125 is corrected. Therefore, positioning of the turret 112 in the X-axis direction and positioning in the generating Y-axis direction can be performed with high accuracy.

  As mentioned above, although one Embodiment of this invention was described, the specific aspect which this invention can take is not restricted to the thing of an upper example at all.

DESCRIPTION OF SYMBOLS 1 Control apparatus 2 NC program memory | storage part 3 Program analysis part 4 Position command part 5 Correction data memory | storage part 6 Position correction part 10 X-axis position control part 11 X-axis speed control part 12 X-axis current control part 15 Y'-axis position control part 16 Y′-axis speed control unit 17 Y′-axis current control unit 20 Z-axis position control unit 21 Z-axis speed control unit 22 Z-axis current control unit 100 Lathe 101 Bed 102 Spindle base 103 Spindle 110 Saddle 111 Tool post 112 Turret 115 Y 'Axis feed mechanism 116 Y' axis servo motor 120 Reciprocating base 125 X axis feed mechanism 126 X axis servo motor 130 Z axis feed mechanism 131 Z axis servo motor

Claims (3)

A second feed shaft that has a first feed shaft and moves the moving body along the first feed shaft; and a second feed shaft that intersects the first feed shaft in a non-orthogonal state; A control method for controlling the operation of the first feed mechanism and the second feed mechanism of a feed device comprising a second feed mechanism for moving the first feed mechanism along a feed axis,
According to positioning data set for each of the first feed axis and the second feed axis, the first feed mechanism and the second feed mechanism are simultaneously operated to make the movable body a virtual feed axis that is orthogonal to the second feed axis. In a positioning control method for positioning in a direction,
After acquiring in advance the positioning accuracy of the moving body in the virtual feed axis direction,
Based on the obtained positioning accuracy in the direction of the virtual feed axis, the straightness in the plane including the second feed axis and the virtual feed axis is estimated in advance for the second feed axis of the second feed mechanism. ,
When positioning the first feed mechanism and the second feed mechanism according to the positioning data to move the moving body in the virtual feed axis direction, the estimated second feed mechanism in the second feed axis direction is used. A correction amount for compensating for the positioning error amount along the first feed axis of the first feed mechanism and the positioning error amount along the second feed axis of the second feed mechanism, obtained based on the straightness, is calculated. The positioning control method is characterized in that each positioning data is corrected according to the calculated correction amount.   The correction amount for compensating the positioning error amount along the first feed axis of the first feed mechanism includes the correction amount for compensating the pitch error along the first feed axis of the first feed mechanism, and the second feed The correction amount for compensating the positioning error along the second feed axis of the mechanism includes a correction amount for compensating for the pitch error along the second feed axis of the second feed mechanism. The positioning control method described.   The correction amount for compensating for the positioning error along the first feed axis of the first feed mechanism includes the correction amount for compensating for the backlash error along the first feed axis of the first feed mechanism, and the second feed 2. The correction amount for compensating a positioning error along the second feed axis of the mechanism includes a correction amount for compensating for a backlash error along the second feed axis of the second feed mechanism. Or the positioning control method of 2.

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