JP2006323773A - Acquisition method for drive controlling correction data - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acquisition method for a drive controlling correction data for a mobile body for smoothly and precisely moving the mobile body moved by two drive shafts. <P>SOLUTION: On a single mobile body 13 fed linearly by a first drive means and a second drive means individually arranged in parallel to a guide rail 12, positioning accuracy of the mobile body 13 is measured by a first measurement axis M1 set in the vicinity of the first drive means and a second measurement axis M2 set in the vicinity of the second drive means. From the positioning accuracy measurement data measured by the first measurement axis M1, drive controlling correction data for the first drive means are calculated, while drive control correction data for the second drive means are calculated from the positioning accuracy measurement data measured by the second measurement axis M2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for acquiring correction data for driving control of a moving body, and more particularly to a method for acquiring correction data for driving control of a moving body such as a work table of a machine tool that is moved by two parallel driving axes. .

  In an NC (numerical control) machine tool, a spindle head that holds a cutter and a table on which a workpiece is placed are moved in three axial directions, ie, an X direction, a Y direction, and a Z direction. For example, in a vertical machining center, the spindle head is moved in the vertical direction (Z-axis), the saddle on which the table is mounted is moved in the front-rear direction (Y-axis), and the table above it is moved in the left-right direction (X-axis). Alternatively, a configuration in which the column holding the spindle head is moved in the left-right direction (X-axis) and the table is moved in the front-rear direction (Y-axis) is used.

  These moving mechanisms such as the spindle head, table, saddle, and column hold the moving body so that it can move linearly along the guide, and are driven by a single drive means consisting of a servo motor, ball screw, linear motor, and the like. Most of them did.

  The drive shaft in this case is best to be an axis that passes through the center of gravity of the moving body. That is, by applying a force to the center of gravity of the moving body, the moving body can be moved straight without generating vibration.

  However, in a machine tool, it is difficult to bring the drive shaft to the center of gravity of the moving body. For example, the center of gravity of the spindle head has a main shaft, and no force can be applied to the center of gravity. In the case of a table, the center of gravity when a heavy workpiece is placed is the space above the workpiece placement surface of the table, and a ball screw cannot be placed there.

  To solve these problems, we propose a machine tool that uses a drive system that aims to achieve the same effect as driving the moving body on two drive shafts with the center of gravity of the moving body in between and pushing the center of gravity. (For example, refer to Patent Document 1).

  In the machine tool described in Patent Document 1, there is a pair of left and right vertical guide rails on the front surface of a column erected on a bed, and a saddle that holds the spindle head is guided by the vertical guide rails and can move up and down. It has become.

The saddle is connected to a pair of left and right ball screws, and the saddle is moved up and down by synchronously rotating two motors that rotationally drive the ball screws.
JP 2003-266257 A

  However, in the driving method of the moving body described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-266257), two ball screws are arranged on two driving shafts sandwiching the center of gravity of the moving body, respectively. Since only the two motors that rotate the ball screw are rotated synchronously, the moving body cannot be driven smoothly due to the parallelism error of the two ball screws, the pitch error of each ball screw, etc. It was also a cause to generate.

  As described above, the machine tool described in Patent Document 1 has a serious problem that the quality of the machined surface is deteriorated due to vibration and the wear of the tool is promoted to shorten the life.

  The present invention has been made in view of such circumstances, and provides a method for acquiring correction data for driving control of a moving body for smoothly and accurately controlling the moving body moved by two drive shafts. The purpose is to do.

  In order to achieve the above-mentioned object, the present invention is supported by a first driving means and a second driving means which are supported so as to be linearly movable along the guide and which are spaced apart from each other and parallel to the guide. In the method of acquiring correction data for driving control of one moving body that is linearly fed, the first measuring axis set in the vicinity of the first driving means and the vicinity of the second driving means are set. The positioning accuracy of the moving body is measured by at least two axes with the second measuring axis, and the positioning accuracy measurement data of the moving body measured by the first measuring axis is used as correction data for the first driving means. The correction data for driving control of the first driving means is input to the memory and the positioning accuracy measurement data of the moving body measured by the second measuring axis is stored in the correction data memory of the second driving means. Enter And calculates the correction data for drive control of the second drive means together.

  Specifically, the moving body is configured with two axes, a first measurement axis set in the vicinity of the first drive means and a second measurement axis set in the vicinity of the second drive means. The positioning accuracy is measured, and the positioning accuracy measurement data of the moving body obtained by the respective measurement axes is input to the correction data memory of the respective drive means, and the drive control correction data of the respective drive means is calculated.

  Based on the drive control correction data of the respective drive means, the first drive means and the second drive means are driven and controlled, and the feed of the moving body is controlled.

  According to the present invention, the positioning accuracy of the moving body is measured in the vicinity of each of the two drive shafts, and the drive control correction data for each drive shaft is calculated from each measurement data. It is possible to suppress yawing during movement caused by variations in machining accuracy of components of the drive shaft, and to move the moving body smoothly with low vibration and with high accuracy.

  Further, the present invention is supported so as to be linearly movable along the guide, and is linearly fed by a first driving means and a second driving means which are spaced apart from each other and provided in parallel to the guide 1. In the method for obtaining correction data for driving control of a single moving body, the positioning accuracy of the moving body is measured on one axis between the first driving means and the second driving means, The positioning accuracy measurement data of the moving body measured in step 1 is input to a correction data memory and drive control correction data for the first drive means and the second drive means is calculated.

  Specifically, the positioning accuracy of the moving body is measured on one axis between the first driving means and the second driving means, and the positioning accuracy of the moving body is measured on the one axis. Data is input to the correction data memory, and based on this measurement data, drive control correction data shared by the first drive means and the second drive means is calculated. Based on this shared drive control correction data, the first drive means and the second drive means are driven and controlled, and the feed of the moving body is controlled.

  According to the present invention, the positioning accuracy of the moving body is measured on one axis between the two drive axes, and the drive control is shared by the first drive means and the second drive means based on the measurement data. Correction data is calculated, and the drive of each moving shaft is controlled based on the shared driving control correction data to control the feed of the moving body. It is possible to move with high accuracy and smooth vibration with low level.

  Further, the present invention is a method for obtaining correction data for driving control of a moving body, wherein the first driving means and the second driving means are each composed of a motor and a ball screw or a linear motor. The moving body is a method for obtaining correction data for driving control of the moving body, which is a table on which a spindle, a saddle, or a workpiece is placed.

  According to the present invention, the spindle head, saddle, or table of a machine tool that is biaxially driven by a driving means comprising a motor and a ball screw or a linear motor can be smoothly moved with low vibration and with high accuracy. Control correction data can be acquired.

  Moreover, this invention measures the positioning accuracy of the said mobile body using a laser length measuring apparatus. According to this, the positioning accuracy of the moving body can be easily measured with high accuracy.

  As described above, according to the method for acquiring correction data for driving control of a moving body according to the present invention, two driving shafts are used in a moving body such as a spindle head of a machine tool, a saddle, or a table on which a work is placed. It is possible to appropriately acquire control correction data for each drive shaft of the moving body that is moved in step (b).

  A preferred embodiment of a method for acquiring correction data for driving control of a moving body according to the present invention will be described in detail below with reference to the accompanying drawings. In each figure, the same number or symbol is attached to the same member.

  FIG. 1 shows a state in which the positioning accuracy of a table on which a workpiece of an NC machine tool is placed is measured. In FIG. 1, for the sake of simplification, the description of the parts other than the column, saddle, spindle head, and other table portions of the NC machine tool is omitted.

  The table portion of the NC machine tool is a table which is a movable body supported so as to be linearly movable in the Y direction in the figure along the guide rails 12 and 12 and the guide rails 12 and 12 provided in parallel to each other on the upper surface of the bed 11. 13. Two ball screws 14 and 15 rotatably supported on the bed 11 by a holder (not shown), a servo motor 16 that rotationally drives the ball screw 14, and a servo motor 17 that rotationally drives the ball screw 15 are provided.

  As the guide rail 12, it is preferable to use a linear ball guide or a guide rail for a linear roller guide to constitute a rolling guide.

  The servo motor 16 and the servo motor 17 are also fixed to the bed 11 by a holder (not shown). Further, nut portions (not shown) of the two ball screws 14 and 15 are connected to the table 13 in a state in which the rotation around the axis is restricted in the axial direction (Y direction in the drawing). . The ball screw 14 and the servo motor 16 constitute a first driving means, and the ball screw 15 and the servo motor 17 constitute a second driving means, and the table 13 is moved by two axes.

  The NC device 20 that controls the operation of the NC machine tool is provided with a motor controller that controls the rotation of the servo motor 16 and the servo motor 17 independently of each other, and controls the rotation of the servo motor 16 and the servo motor 17. By doing so, the feed control of the table 13 is performed.

  A laser length measuring device 30 is used for measuring the positioning accuracy of the table 13. The laser length measuring device 30 used in this embodiment is a separation type laser interferometer described in Japanese Utility Model Laid-Open No. 63-159706.

  This separation-type laser interferometer connects the laser light source 31 and the interference optical units 32 and 34 with optical fibers 31A and 31B such as single mode fibers or polarization plane preserving fibers, thereby interfering with the laser light source 31. The laser length measuring device 30 eliminates the need for alignment adjustment between the units 32 and 34 and increases the degree of freedom of arrangement between them.

  The signal processing unit of the laser length measuring device 30 is also separated from the interference optical units 32 and 34 and incorporated in an expansion box 36 of a notebook personal computer (PC) 37 corresponding to the measurement control unit. That is, a photodetector is provided in the interference optical units 32 and 34 to convert the interference fringe signal into an electrical signal, and the electrical signal cable is connected to the counter board in the expansion box 36.

  In measuring the positioning accuracy of the table 13, the first measurement axis M <b> 1 is set near the ball screw 14, and the second measurement axis M <b> 2 is set near the ball screw 15. That is, the corner cube 33 is attached to the upper position of the ball screw 14 on the end face of the table 13, and the interference optical unit 32 is set so as to face the corner cube 33. Further, a corner cube 35 is attached to an upper position of the ball screw 15 on the end face of the table 13, and the interference optical unit 34 is set so as to face the corner cube 35. The corner cube 33 and the corner cube 35 have permanent magnets attached to the bottom of the case, and are fixed to the end surface of the table 13 by magnetic force.

  The laser light L1 emitted from the laser light source 31 through the optical fiber 31A and the interference optical unit 32 is reflected by the corner cube 33 and returns to the interference optical unit 32, and interference fringes are generated in the interference optical unit 32.

  As the table 13 moves, the interference fringes move. The light detectors in the interference optical unit 32 convert the light and darkness of the interference fringes into electrical signals. The counter board in the expansion box 36 counts the number of interference fringes. Thus, the amount of movement of the table 13 on the first measurement axis M1 is calculated.

  Similarly, the laser light L2 emitted from the laser light source 31 through the optical fiber 31B and the interference optical unit 34 is reflected by the corner cube 35 and returns to the interference optical unit 34 to generate interference fringes in the interference optical unit 34. . The number of interference fringes is also measured, and the amount of movement of the table 13 on the second measurement axis M2 is calculated.

  The PC 37 which is the measurement control unit is installed with correction data memory for the first drive means and second drive means and positioning error correction software, and positioning accuracy data on the first measurement axis M1 of the table 13 is installed. Is input to the correction data memory of the first driving means, and the correction data of the first driving means is calculated from the positioning accuracy data on the first measurement axis M1.

  Further, the positioning accuracy data on the second measurement axis M2 of the table 13 is input to the correction data memory of the second drive means, and the second drive means is determined from the positioning accuracy data on the second measurement axis M2. Data for correction is calculated.

  The calculated correction data for the first drive means and correction data for the second drive means are sent from the PC 37 to the NC device 20 of the NC machine tool, and the servo motor 16 of the first drive means and the second The servo motors 17 of the driving means are individually controlled for rotation. The PC 37 and the NC device 20 are connected by an RS-232C interface.

  In this way, the first driving means and the second driving means are individually set with correction data, and are driven and controlled based on the respective correction data. For example, the two ball screws 14 and 15 Yawing and the like during table movement caused by variations in processing accuracy are suppressed, and the table 13 is smoothly fed with low vibration, and high-precision positioning is performed.

  Next, a specific flow of operation will be described. FIG. 2 is a flowchart for explaining the positioning accuracy measurement of the table 13 and the flow of creation of drive correction data. First, the operator sets the laser length measuring device 30 on the table 13 portion of the NC machine tool as shown in FIG.

  Next, the NC device 20 of the NC machine tool is switched to a tape operation mode that operates with an external signal, and the operation button is pressed to wait for an external signal (step S11). Next, measurement conditions are set in the PC 37, the positioning error correction software is automatically started (step S12), and a reference point return command is issued so that the table 13 is positioned at the initial position (step S13).

  This reference point return command is sent to the NC device 20 via the RS-232C interface, and the table 13 is returned to the reference point (step S14). The positioning accuracy of the table 13 is measured with this reference point as the initial position.

  Next, the PC 37 issues a measurement start position movement command so that each of the table 13, the saddle, and the spindle head moves to the measurement start position (step S15). This is because even if the positioning accuracy of the table 13 is measured, the measurement value slightly changes depending on the positions of the saddle and the spindle head, and therefore the positioning accuracy of the table 13 is measured by positioning the saddle and the spindle head at a predetermined position. is there.

  This command is also sent to the NC device 20, and the table 13, saddle, and spindle head are sent to the measurement start position (step S16). Next, positioning error measurement (positioning accuracy measurement) of the table 13 is started according to the set measurement conditions (step S17), and positioning error data is acquired. This is acquired individually on the first measurement axis M1 and the second measurement axis M2, and stored in the correction data memories of the first drive means and the second drive means of the PC 37, respectively (step S18). ).

  Next, it is determined whether the designated number of measurement points set in the measurement conditions has been measured (step S19). If the designated measurement point has not been measured, the process returns to step S18 to obtain positioning error data for the next measurement point. And repeat this action.

  If the designated number of measurement points has been measured in step S19, it is then determined whether the designated number of measurements set in the measurement conditions has been completed (step S20), and if the designated number of measurements has not been reached, the process returns to step S17. The operations from step S17 to step S20 are repeated.

  If it is determined in step S20 that the designated number of measurements has been completed, then the PC 37 calculates drive correction value data for the first drive means based on the measurement data on the first measurement axis M1, and the second Based on the measurement data on the measurement axis M2, drive correction value data for the second drive means is calculated (step S21). For calculating the correction value data, for example, as described in Japanese Patent Application Laid-Open No. 10-11706, a method of calculating the entire correction value data by complementing the data at a non-measurement position by a predetermined complementing method is used.

  Next, the PC 37 issues a correction value data transfer command to transfer the correction value data of the first driving means and the correction value data of the second driving means calculated individually to the NC device 20 (step S22). The NC device 20 automatically receives the correction value data and loads it into the memory (step S23).

  Next, the PC 37 issues a reference point return command so that the table 13 returns to the reference point (step S24), and the NC device 20 receiving the signal returns the table 13 to the reference point (step S25). Next, these series of data processing results are printed by a printer (not shown), and the flow of measuring the feed accuracy of the table 13 and creating the feed amount correction value is completed.

  The NC device 20 drives and controls the first driving means with position data obtained by adding the correction value of the driving correction data of the first driving means taken into this memory to the feedback signal from the encoder (not shown) of the servo motor 16. The table 13 is moved with high accuracy by controlling the driving of the second driving means with the position data obtained by adding the correction value of the driving correction data of the second driving means to the feedback signal from the encoder (not shown) of the servo motor 17. .

  When the table 13 is driven with the correction position data including the correction value, the positioning accuracy can be measured again to check whether it is within the specified value. Further, the positioning accuracy may be confirmed according to a predetermined inspection item of the NC machine tool defined by ISO 230-2 or the like.

  Note that positioning accuracy measurement and feed amount correction value generation can be performed in the same manner for the X-axis and Z-axis other than the Y-axis (table drive axis). In this case, it is also possible to fully automatically process the XYZ three axes based on the fully automatic measurement system for a numerically controlled machine tool described in JP-A-9-244718.

  FIG. 3 is a perspective view for explaining the second invention. In this second invention, there is only one measurement axis, and the measurement axis M is provided at a position equidistant from the ball screw 14 and the ball screw 15. That is, the corner cube 33 is attached at equal intervals from the ball screw 14 and the ball screw 15 on the end surface of the table 13, and the interference optical unit 32 is set so as to face the corner cube 33.

  Laser light L emitted from the laser light source 31 through the optical fiber 31 </ b> A and the interference optical unit 32 is reflected by the corner cube 33 and returns to the interference optical unit 32 to generate interference fringes in the interference optical unit 32. Other configurations and operations are the same as those of the embodiment shown in FIG.

  Correction data is calculated based on the measurement data obtained by the feed accuracy measurement on the measurement axis M, and the calculated correction value is used as correction data common to the first drive means and the second drive means. The NC apparatus 20 moves the table 13 by applying the common correction data to the first driving means and the second driving means.

  When the pitch accuracy of the ball screw 14 and the ball screw 15 is substantially the same, the correction value is calculated with a measured value on one axis that is equidistant from the first driving means and the second driving means as in the second invention. By applying this to each of the first driving means and the second driving means, the table 13 can be moved with high accuracy and smooth vibrations at a level that does not impede practical use only by measurement on one axis. It can be carried out.

  Although the measurement axis is provided on one axis that is equidistant from the first driving means and the second driving means, the measuring axis is provided on one axis at a predetermined position between the first driving means and the second driving means. A measuring axis may be provided in the. In this case, the first drive means and the second drive means are distributed separately according to the position of the measurement axis without using the common drive control correction data for the first drive means and the second drive means. It is also possible to calculate drive control correction data.

  In this embodiment, the NC machine tool table, saddle, and spindle head have been described as the moving body. However, the present invention is not limited to the NC machine tool and may be applied to a normal machine tool, a measuring machine, or the like. The mobile device can be applied to drive a column.

  In addition, the first driving means and the second driving means have been described using a ball screw and a servo motor. However, the present invention is not limited to this, and a linear motor may be used, and the motor is not limited to a servo motor.

  Further, a laser length measuring device is used for measuring the positioning accuracy of the table (moving body) 13, and the laser length measuring device also uses a separation type laser interferometer, but the invention is not limited to the separation type laser interferometer. The interferometer and the interference optical unit may be an integrated laser interferometer, and not only the laser length measuring device but also various known measuring devices can be used.

The perspective view explaining the acquisition method of the correction data for drive control concerning an embodiment of the invention Flowchart for explaining a method for acquiring correction data for drive control according to an embodiment of the present invention The perspective view explaining embodiment of 2nd invention

Explanation of symbols

  DESCRIPTION OF SYMBOLS 12 ... Guide rail, 13 ... Table (moving body), 14, 15 ... Ball screw, 16, 17 ... Servo motor (motor), 30 ... Laser length measuring device, M1 ... 1st measuring axis, M2 ... 2nd measurement axis

Claims (5)

Drive of one moving body supported linearly along the guide and linearly fed by first and second driving means spaced apart from each other and parallel to the guide. In the control correction data acquisition method,
Measure the positioning accuracy of the moving body with at least two axes, a first measurement axis set in the vicinity of the first drive means and a second measurement axis set in the vicinity of the second drive means. And
The positioning accuracy measurement data of the movable body measured with the first measurement axis is input to the correction data memory of the first drive unit, and the drive control correction data of the first drive unit is calculated, The positioning accuracy measurement data of the movable body measured with the two measurement axes is input to the correction data memory of the second drive means, and the drive control correction data of the second drive means is calculated. A method for obtaining correction data for drive control. Drive of one moving body supported linearly along the guide and linearly fed by first and second driving means spaced apart from each other and parallel to the guide. In the control correction data acquisition method,
Measuring the positioning accuracy of the movable body on one axis between the first driving means and the second driving means;
Positioning accuracy measurement data of the moving body measured on the one axis is input to a correction data memory and drive control correction data for the first drive means and the second drive means is calculated. Acquisition method of control correction data.   The acquisition of correction data for driving control of a moving body according to claim 1 or 2, wherein the first driving means and the second driving means each comprise a motor and a ball screw or a linear motor. Method.   The method for obtaining correction data for driving control of a moving body according to any one of claims 1, 2, or 3, wherein the moving body is a spindle head of a machine tool, a saddle, or a table on which a workpiece is placed. .   The positioning accuracy of the moving body is measured using a laser length measuring device, and the correction data for driving control of the moving body according to any one of claims 1, 2, 3, or 4 is provided. Acquisition method.

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