JPH054150A - Method and device for work position/attitude correction with table deflection taken into account - Google Patents

Abstract

PURPOSE:To make absolute location of a work in a three-dimensional space by correcting the work position error and inclination error generated by deflection etc. of an X-axis, Y-axis, and Z-axis table. CONSTITUTION:First a model work is placed on a work table 40, which is moved in the X-axis, Y-axis, and Z-axis direction, and the axial direction position and inclination errors generated by the deflection of tables 32, 33, 34 in each position are measured and stored in a memory circuit previously. When an actual work to be processed is placed on the work table 40, a position/ inclination correcting circuit reads the axial direction position error and inclination error out of a memory circuit as correcting values, and the tables 32, 33, 34 are moved while these erroneous portions undergo correction, and at the same time, the work table 40 is rotated round the axes. In this manner, the work table 40 with a work placed thereon is moved while undergoing correction of error due to deflection, and also the attitude of the work is corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention corrects a position error and a tilt error of a work caused by bending of an X-axis, Y-axis, Z-axis table or the like to perform absolute positioning of a work in a three-dimensional space. And a 6-axis table device used in the method.

[0002]

2. Description of the Related Art Conventionally, a machine tool has, for example, X, Y, Z.
Among the X-axis, Y-axis, and Z-axis tables that move in the axial direction, the work is loaded on the table at the uppermost position, and while each table is moved in each direction, various processing is performed on this work. ing. Each table is usually moved by a precision ball screw. However, the screw shaft of the ball screw has a pitch error and a backlash error. Therefore, there is a table position correction method in which the pitch error and the backlash error are stored in advance and the table is moved while correcting the errors.

[0003]

However, in such a correcting method, for example, as shown in FIG. 8, the support column 22 for guiding the elevation of the Z-axis table 21 is indicated by a broken line due to the weight of the work W or the like. When tilted to, it is not possible to accurately control the position of the table by correcting the pitch error and backlash of each axis alone. That is, even if the Z-axis table 21 is moved up and down and the X-axis table 23 is moved based on the pitch error correction and the backlash error correction to control the position of the work W to the position shown by the solid line, the work W remains tilted. However, there is a problem that it is not possible to control to a normal posture as shown by the imaginary line.

[0004]

The present invention is provided on the table at the highest position among the X-axis, Y-axis, and Z-axis tables that move in the X-, Y-, and Z-axis directions, respectively. When a model work is loaded on the work loading table which can be rotated around, the axial position error and the tilt error at the X, Y and Z axis coordinate positions of the work loading table are stored in the storage circuit, A position / tilt correction circuit corrects the axial position error amount and the tilt error amount stored in the storage circuit during the actual work processing, and the X, Y, and Z axial positions of the work loading table and the respective positions. A method for correcting the position / orientation of a work, which is characterized by correcting a rotation angle around an axis, and an X that moves in the X, Y, and Z axis directions, respectively.
Axis, Y-axis, Z-axis table, a work loading table provided on the table at the uppermost position thereof so as to be rotatable around the X, Y, Z axes, and X of the work loading table. , A Y-axis and Z-axis coordinate position, a storage circuit for storing the axial position error and the tilt error, and the X-axis, the Y-axis by correcting the axial position error and the tilt error stored in the storage circuit. The above problem is solved by a 6-axis table device having an axial position of a Z-axis table and a position / tilt correction circuit for correcting the rotation angles of the work loading table around the X, Y, and Z axes. is there.

[0005]

First, a model work is placed on the work loading table, the work loading table is moved to various positions in the X-axis, Y-axis, and Z-axis directions, and an axial position error caused by bending of each table at each position, and , The inclination is measured, and the axial position error and the inclination error are stored in the storage circuit in advance. This memory is stored according to the weight of the work. When the work to be actually processed is placed on the work stacking table, the X, Y and Z axis tables are moved to various positions according to the processing to be performed. At this time, the position / tilt correction circuit , The axial position error and the tilt error are read out from the memory circuit as correction values, each table is moved while correcting the axial position error and the tilt error, and the work loading table is rotated around each axis. Let In this way, the work loading table on which the work is placed moves while the axial position error and the tilt error due to the bending are corrected, and the posture of the work is also corrected.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. The Z-axis table 32 that moves in the vertical direction (Z-axis direction) is provided on the column 31 of the 6-axis table device 30 (see FIG. 1).
Is included. The Z-axis table 32 includes an X-axis table 33 that moves in the left-right direction (X-axis direction) in FIG. The X-axis table 33 includes a Y-axis table 34 that moves in the front-back direction (Y-axis direction) of FIG. The Y-axis table 34 includes a Z-axis rotating frame 36 that rotates around a Z-axis rotating shaft 35. The Z-axis rotating frame 36 includes a rotating shaft 37 in the X-axis direction.
An X-axis tilting frame 38 that tilts about is provided. The X-axis tilting frame 38 includes a rotation shaft 39 in the Y-axis direction.
A work loading table 40 that tilts around the center is provided.

Each table 3 is provided between the column 31 and the Z-axis table 32 and between each table 32, 33, 34.
A known linear motion bearing (not shown) for guiding the movement of 2, 33, 34 is provided. Also, X-axis, Y-axis,
The Z-axis tables 33, 34 and 32 are known precision ball screws 41 and 42 (ball screws for the Z-axis table are not shown).
It is designed to be moved by. Each precision ball screw has a Z-axis, X-axis, and Y-axis table servo motor 51, 5
2, 53 (see FIG. 2). Furthermore, the rotation axes 35, 37, 3 around the Z, X, and Y axes
9 is also rotated by a Z-axis rotary frame servo motor 54, an X-axis tilting frame servo motor 55, and a work loading table servo motor 56.

The 6-axis table device 30 has a control means 60 as shown in FIG. This control means 60
Has a correction data storage circuit (storage circuit) 61, a position / tilt command circuit 62, a position / tilt correction circuit 63, and a motor control circuit 64. Correction data storage circuit 61
Is a pitch error, backlash error, pitching error for each of the X-axis, Y-axis, and Z-axis tables 33, 34, 32 at the X-axis, Y-axis, and Z-axis coordinate positions of the work loading table 40 on which the model work is loaded. This circuit stores rolling error, yawing error, and the like. The pitching error, rolling error, and yawing error are caused by the bending of the column 31, the tables 32, 33, 34, and the like.

As shown in FIG. 3, the backlash error is caused by a ball screw when the tables 32, 33 and 34 are moved from point a to point b and then returned to point c between points a and b. This is the position error due to the backlash of the screw shaft. The position of the broken line is a regular position. As shown in FIG. 4, the pitching error is an error that occurs when the tables 32, 33, 34 are tilted in a direction parallel to the moving direction.
The position of the broken line is a regular position. The rolling error is an error that occurs when the table 32, 33, 34 is tilted around the axis in the moving direction, as shown in FIG. The position of the broken line is a regular position. Then, as shown in FIG. 6, the yawing error is an error that occurs when the table 32, 33, 34 is horizontally inclined around an axis perpendicular to the axis of the moving direction. The position of the broken line is a regular position.

The position / tilt command circuit 62 moves the work loading table 40 to a desired position and takes a desired posture based on the data inputted from the outside, and the axial movement amount of each table and each table. It is a circuit that sets the rotation angle around the axis. The position / tilt correction circuit 63 is a circuit that corrects the axial position setting data and the rotation angle setting data of the work loading table based on the signal from the position / tilt command circuit 62 using the correction data stored in the correction data circuit. .
The motor control circuit 64 is a circuit that controls each servo motor based on a control signal from the position / tilt correction circuit 63.

Next, the operation will be described. First, the model work is placed on the work loading table 40, the work loading table 40 is moved to various positions of the X axis, the Y axis, and the Z axis, and the axial position error of each table and the tilt caused by the bending are measured, It is stored in the position / tilt correction circuit as a pitch error, backlash error, pitching error, rolling error, yawing error, etc. This memory is stored according to the weight of the work. Since the method of measuring such a value is well known, its description is omitted. The number of measurement points should be as large as possible, but as an example, it is the number obtained by multiplying the stroke length in each axial direction by the integer value obtained by dividing the lead length of the ball screw. When the work to be actually processed is placed on the work stacking table 40, the X, Y and Z axis tables 33, 34 and 32 are moved to various positions according to the processing to be performed. Tilt correction circuit 63
Reads out each of the above errors as a correction value from the correction data storage circuit 61, corrects the axial movement amount of each table from the position / tilt command circuit 62 and the value for setting the rotation angle around each axis, A motor control signal is sent to the motor control circuit 64.

A motor control circuit 6 which receives a motor control signal
Reference numeral 4 indicates the rotation of the servo motor set by the position / tilt correction circuit 63 while operating each servo motor via the amplifiers 71 to 76 and detecting the rotation speed and rotation angle of the servo motor by the pulse generators 81 to 86. Operate each servo motor until it matches the number and rotation angle. In this way, the work loading table 40 on which the work is placed is corrected for pitching error, backlash error, pitching error, rolling error, yawing error, etc., which are caused by the bending of each table, and the work position is set to the normal position. Controlled by the attitude of.

In order to make the above operation easier to understand from a different angle, FIG. 7 shows the 6-axis table device 30 of FIG.
Z-axis table 32, (Y) rotary shaft 39, X-axis table 3
FIG. 3 is a modified view in which 3 is put together in one place for convenience. In FIG. 7, when the work W, which should originally be in the position of the solid line, moves the support 31 to the position of the broken line as shown by the broken line due to the weight of the work W, first, the (Y) rotary shaft 39 is rotated. Then, as shown by the imaginary line, the posture of the work W is corrected to be horizontal. Next, the height (H) depressed by the bending of the support column 31 and the amount (L) displaced to the right are moved up by the Z-axis table 32 and moved left by the X-axis table 33 (pitching correction). ) And to fix. In this way, the work W has each error corrected by the control means 60,
It will be set in a regular position and in a regular posture.

In the above embodiment, the X axis is on the Z axis,
Although the Y-axis table is mounted, the Z-axis table may be mounted on the X-axis and Y-axis tables. Further, axial position error, tilt error, etc. of each table caused by a change in ambient temperature can be similarly corrected.

[0015]

According to the position correcting method and apparatus of the present invention,
Axial position error and tilt error caused by bending of the X-axis, Y-axis, and Z-axis tables can be corrected, and the work loading table can be accurately moved to a desired position (absolute position correction, that is, The posture can be corrected). In other words, it is not necessary to set the rigidity of the mechanically moving portion to a large value as in the conventional case in order to suppress the bending, and as a result, the overall weight of the device can be reduced. Further, even if the processing accuracy of the parts of each table is somewhat poor, if the accuracy is reproducible, the absolute positioning accuracy of the work can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a 6-axis table device used in a position / orientation correction method of the present invention.

FIG. 2 is a circuit diagram of control means.

FIG. 3 is a diagram illustrating backlash error.

FIG. 4 is a diagram illustrating a pitching error.

FIG. 5 is a diagram illustrating a rolling error.

FIG. 6 is a diagram illustrating a yawing error.

FIG. 7 is a simplified operation explanatory diagram.

FIG. 8 is a diagram for explaining a conventional operation.

[Explanation of symbols]

30 6-axis table device 32 Z-axis table 33 X-axis table 34 Y-axis table 35 rotation axis 37 rotation axis 39 rotation axis 40 work loading table 61 Correction data storage circuit (storage circuit) 63 Position / tilt correction circuit

Claims (2)

[Claims] 1. An X moving in the X, Y, and Z axis directions, respectively.
When loading model work on a work loading table which is provided on the table at the uppermost position among the axis, Y axis and Z axis tables and is rotatable around the X, Y and Z axes Axial position error and tilt error at the X, Y, and Z axis coordinate positions of the table are stored in the storage circuit,
The position / tilt correction circuit corrects the axial position error amount and the tilt error amount stored in the storage circuit during the actual work processing, and the X, Y, Z of the work loading table is corrected.
A method for correcting a position / orientation of a work, which comprises correcting an axial position and a rotation angle around each of the axes. 2. An X which moves in the X, Y and Z axis directions, respectively.
Axis, Y-axis, Z-axis table, a work loading table provided on the table at the uppermost position thereof so as to be rotatable around the X, Y, Z axes, and X of the work loading table. , A Y-axis and Z-axis coordinate position, a storage circuit for storing the axial position error and the tilt error, and the X-axis, the Y-axis by correcting the axial position error and the tilt error stored in the storage circuit. 6. A position / tilt correction circuit for correcting the axial position of the Z-axis table and the rotation angle of the work loading table around the X, Y, and Z axes.
Axis table device.