JP2012240138A - Method and device for correcting thermal displacement of machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for correcting thermal displacement of a machine tool capable of accurately correcting thermal displacement even when a base of the machine tool is thermally deformed.SOLUTION: In first and second level measurement value acquiring steps (steps S3-S8), first and second level measurement values are acquired as measurement angles of a level 70 with respect to a vertical axis at a first angle and a second angle rotated to 180 degrees from the first angle from the level 70 stored in a rotating body 60 supported by the base 10. In a tilt angle calculating step (step S9), a tilt angle of the rotating body 60 with respect to the vertical axis canceling thermal deformation of the level 70 can be calculated based on the first and second level measurement values. Accordingly, thermal deformation can be accurately corrected even when the base 10 is thermally deformed.

Description

  The present invention relates to a thermal displacement correction method and a thermal displacement correction apparatus for a machine tool.

  A machine tool processes a workpiece by controlling the position of each drive shaft by a control device. In this machine tool, the structure may be thermally deformed due to heat generation due to internal factors such as machining by tools and rotation of the motor, and heat transfer due to external factors such as room temperature fluctuations in the installation environment. Since the thermal deformation of the structure affects the processing position, the processing accuracy may be reduced.

  Therefore, for example, Patent Document 1 discloses an apparatus for measuring the inclination of a main shaft supported by a column when the column of a machine tool is thermally deformed. This device includes a string having an upper end attached to the column and a weight attached to the lower end and hanging vertically, and a distance sensor attached to the string and measuring the distance to the measured portion of the column. Yes. Then, the inclination of the spindle due to the thermal deformation of the column is measured based on the distance to the measured portion of the column measured by the distance sensor. Since this apparatus measures the inclination of the main shaft due to the thermal deformation of the column based on the level measurement principle, the thermal displacement correction performed after the measurement can be performed with high accuracy.

JP 2008-155339 A

  In general, a bed (base) of a machine tool tends to generate a temperature gradient due to a difference in heat capacity in the vertical direction, and the entire bed is deformed due to a difference in thermal expansion between the upper surface and the lower surface of the bed. That is, the bed is provided with a thick upper surface on which a slide or the like is placed, and a thin lower surface. For this reason, when the temperature of the bed rises, the temperature of the lower surface rises faster than the upper surface, so that the expansion amount of the lower surface becomes larger than the expansion amount of the upper surface, and the bed warps in a concave shape. Then, when the temperature of the lower surface and the upper surface becomes constant thereafter, the expansion amount of the lower surface becomes equal to the expansion amount of the upper surface, so that the bed returns to the horizontal state. On the other hand, when the temperature of the bed decreases, the temperature of the lower surface lowers faster than the upper surface, so that the expansion amount of the lower surface becomes smaller than the expansion amount of the upper surface, and the bed rises in a convex shape. Then, when the temperature of the lower surface and the upper surface becomes constant thereafter, the expansion amount of the lower surface becomes equal to the expansion amount of the upper surface, so that the bed returns to the horizontal state. The workpiece placed on the bed tilts due to the thermal deformation of the bed, and it is necessary to measure the tilt. However, the apparatus described in Patent Document 1 described above can be applied to a column extending in the vertical direction, but is difficult to apply to a bed extending in the horizontal direction. A device that directly attaches the level to the measurement reference plane of the bed and measures the tilt of the workpiece due to thermal deformation of the bed is conceivable, but the level itself may be thermally deformed to cause measurement errors. Therefore, there is a problem that the accuracy of the thermal displacement correction performed after the measurement is lowered.

  The present invention has been made in view of such circumstances, and provides a thermal displacement correction method and a thermal displacement correction apparatus for a machine tool that can correct thermal displacement with high accuracy even if the base of the machine tool is thermally deformed. The purpose is to provide.

(Machine tool thermal displacement compensation method)
(Claim 1) A thermal displacement correction method for a machine tool according to the present invention includes a movable body that can move relative to a base of the machine tool, and a rotation that intersects the base or the horizontal axis supported by the movable body. In a thermal displacement correction method for a machine tool comprising a rotating body that rotates about an axis, a level measurement direction of a level built in the rotating body is at a first angle in a state that coincides with a direction in which thermal displacement correction is performed. A first level measurement value acquiring step of acquiring a first level measurement value as a measurement angle of the level with respect to the vertical axis, and a second angle index for indexing the rotary body to a position rotated 180 degrees from the first angle. A second level measurement value acquisition step of acquiring a second level measurement value as a measurement angle of the level with respect to the vertical axis at the second angle by the level, and the first and second level measurement values On the basis of the, An inclination angle calculation step for obtaining an inclination angle of the rotation axis of the rotating body with respect to the vertical axis, and a correction value calculation step for obtaining a correction value for the command position of the moving body of the machine tool based on the NC angle based on the inclination angle And a correction step of correcting the command position with the correction value.

  (Claim 2) In the thermal displacement correction method for the machine tool, when the level measurement direction of the level does not coincide with the direction for performing thermal displacement correction, the thermal displacement correction method as the direction for performing the thermal displacement correction. A first angle indexing step of indexing the rotating body to one angle, wherein the first level measurement value acquiring step includes the vertical axis at the first angle indexed in the first angle indexing step. The first level measurement value may be obtained as the measurement angle of the level relative to.

  (Claim 3) The rotating body may have a rotation axis in the vertical axis direction.

  (Claim 4) Moreover, the said level is good to be incorporated in the rotation center of the said rotary body.

  (Claim 5) Further, a machining position moving step of moving the movable body to a machining position is provided, and the first level measurement value acquisition means is configured such that the movable body is indexed to the first angle at the machining position. After that, the first level measurement is obtained.

(Machine tool thermal displacement compensation device)
(Claim 6) The thermal displacement correction device for a machine tool according to the present invention comprises a movable body that can move relative to the base of the machine tool, and a rotation that intersects the base or the horizontal axis supported by the movable body. In a thermal displacement correction apparatus for a machine tool comprising a rotating body that rotates about an axis, a level built in the rotating body, and a level measurement direction of the level coincides with a direction in which thermal displacement correction is performed If the level measurement direction of the level is not coincident with the direction for performing the thermal displacement correction, the direction for performing the thermal displacement correction is determined. Indexing control means for indexing control of the rotating body to the first angle and indexing control to the second angle rotated 180 degrees from the indexed first angle, and at the first and second angles Measurement of the spirit level with respect to the vertical axis Level measurement value acquisition means for acquiring first and second level measurement values by the level as degrees, and the vertical axis line based on the first and second level measurement values acquired by the level measurement value acquisition means An inclination angle calculating means for obtaining an inclination angle of the rotation axis of the rotating body with respect to the above, and a correction value for the command position of the moving body of the machine tool by the NC program based on the inclination angle calculated by the inclination angle calculating means And a correction means for correcting the command position based on the correction value calculated by the correction value calculation means.

  (Claim 1) According to the present invention, in the first and second level measurement value acquisition steps, the first angle and the first angle rotate 180 degrees from the level built in the rotating body supported by the base. The first and second level measurement values are acquired as the measurement angle of the level with respect to the vertical axis at the second angle. Thereby, in the inclination angle calculation step, the inclination angle of the rotation axis of the rotating body with respect to the vertical axis that cancels the thermal deformation of the level can be obtained based on the first and second level measurement values. Therefore, even if the base is thermally deformed, the thermal displacement can be corrected with high accuracy.

  (Claim 2) Since the level can be measured only in one direction, if the level measurement direction of the level does not coincide with the direction in which the thermal displacement correction is performed, the level is determined as the direction in which the thermal displacement correction is performed. The rotating body is indexed at the first angle. This makes it possible to accurately correct the thermal displacement.

  (Claim 3) Since the level is a device for measuring whether or not the measurement surface (upper surface) of the rotating body is horizontal, in particular, the inclination angle of the rotating axis of the rotating body with respect to the vertical axis is measured with high accuracy. Therefore, highly accurate thermal displacement correction is possible. As a rotating body having a rotation axis in the vertical axis direction, it can be applied to, for example, a turntable of a horizontal machining center or a main spindle of a vertical lathe.

  (Claim 4) By incorporating a spirit level at the center of rotation of the rotating body, it becomes difficult to be affected by thermal deformation of the rotating body, and the tilt angle of the rotation axis of the rotating body can be measured with high accuracy. .

  (Claim 5) Since the base tilts due to thermal deformation, the tilt angle of the rotation axis of the rotating body varies depending on the moving position of the moving body. Therefore, by moving the moving body to the actual processing position and measuring the tilt angle of the rotation axis of the rotating body, it is possible to perform highly accurate processing.

  (Claim 6) According to the thermal displacement correction apparatus for a machine tool of the present invention, the same effects as those in the above-described thermal displacement correction method for a machine tool can be obtained.

It is a perspective view showing the whole machine tool composition concerning an embodiment of the invention. It is a figure which shows schematic structure of the machine tool of FIG. 1, and a thermal displacement correction apparatus. It is a flowchart for demonstrating operation | movement of the thermal displacement correction apparatus of FIG. (A), (B) is a figure for demonstrating thermal displacement correction | amendment. It is a flowchart for demonstrating another operation | movement of the thermal displacement correction apparatus of FIG.

(1. Machine configuration of machine tool)
As an example of the machine tool 1, a horizontal machining center will be described as an example and will be described with reference to FIGS. In other words, the machine tool is a machine tool having three rectilinear axes (X, Y, Z axes) orthogonal to each other and a rotation axis (B axis) in the vertical axis direction as drive axes.
As shown in FIGS. 1 and 2, the machine tool 1 includes a bed (corresponding to a “base” of the present invention) 10, a column 20 (corresponding to a “moving body” of the present invention), and a saddle 30 ( A rotary main shaft 40, a table (corresponding to the “moving body” of the present invention) 50, and a turntable (corresponding to the “rotating body” of the present invention) 60; And a level 70, a control device 80, and a thermal displacement correction device 90.

  The bed 10 has a substantially rectangular shape and is disposed on the floor. However, the shape of the bed 10 is not limited to a rectangular shape. On the upper surface of the bed 10, a pair of X-axis guide rails 11 a and 11 b on which the column 20 can slide is formed in parallel to each other so as to extend in the X-axis direction (horizontal direction). Further, the bed 10 is provided with an unillustrated X-axis ball screw for driving the column 20 in the X-axis direction between the pair of X-axis guide rails 11a and 11b. The X-axis ball screw is rotated. A driving X-axis motor 11c is disposed.

  Further, on the upper surface of the bed 10, a pair of Z-axis guide rails 12 a and 12 b on which the table 50 can slide extend in the Z-axis direction (horizontal direction) orthogonal to the X-axis direction and are parallel to each other. Is formed. Further, the bed 10 is provided with an unillustrated Z-axis ball screw for driving the table 50 in the Z-axis direction between the pair of Z-axis guide rails 12a and 12b. The Z-axis ball screw is rotated. A Z-axis motor 12c to be driven is disposed.

  A pair of X-axis guide grooves 21a and 21b are formed on the bottom surface of the column 20 so as to extend in the X-axis direction and in parallel to each other. In the column 20, a pair of X-axis guide grooves 21a and 21b are fitted on the pair of X-axis guide rails 11a and 11b via ball guides 22a and 22b so that the column 20 can move in the X-axis direction with respect to the bed 10. The bottom surface of the column 20 is in close contact with the top surface of the bed 10.

  Further, on a side surface (sliding surface) 20a parallel to the X axis of the column 20, a pair of Y axis guide rails 23a and 23b on which the saddle 30 can slide extends in the Y axis direction (vertical direction), and Are formed parallel to each other. Further, the column 20 is provided with a Y-axis ball screw (not shown) for driving the saddle 30 in the Y-axis direction between the pair of Y-axis guide rails 23a and 23b. The Y-axis ball screw is rotated. A Y-axis motor 23c to be driven is disposed.

  A pair of Y-axis guide grooves 31a and 31b are formed on the side surface 30a of the saddle 30 facing the sliding surface 20a of the column 20 so as to extend in the Y-axis direction and in parallel with each other. A pair of Y-axis guide grooves 31 a and 31 b are fitted into the pair of Y-axis guide rails 23 a and 23 b so that the saddle 30 can move in the Y-axis direction with respect to the column 20, and the side surface 30 a of the saddle 30 is aligned with the column 20. Are closely in contact with the sliding surface 20a.

  The rotary spindle 40 is rotatably provided by a spindle motor 41 accommodated in the saddle 30 and supports a tool 42. The tool 42 is fixed to the tip of the rotation main shaft 40 and rotates with the rotation of the rotation main shaft 40. Further, the tool 42 moves in the X-axis direction and the Y-axis direction with respect to the bed 10 as the column 20 and the saddle 30 move. The tool 42 is, for example, a ball end mill, an end mill, a drill, a tap, or the like.

  The table 50 is provided on the pair of Z-axis guide rails 12 a and 12 b so as to be movable in the Z-axis direction with respect to the bed 10. A turntable 60 is supported on the upper surface of the table 50 so as to be rotatable about the B axis in the vertical direction.

  The turntable 60 is rotatably provided by a B-axis motor 61 accommodated in the bed 10 and fixes the workpiece W by magnetic adsorption or the like.

  The level 70 determines whether or not the measurement surface of the turntable 60 (the surface on which the workpiece W is placed) is horizontal, that is, the angle formed between the normal line of the measurement surface of the turntable 60 and the vertical axis. It is a device that measures as a measurement value.

  The level 70 is built in the rotation center C of the turntable 60 and outputs a level measurement value signal. Although the details will be described later, the level 70 can accurately calculate the inclination angle of the rotation axis B of the turntable 60 with respect to the vertical axis associated with the thermal deformation of the bed 10, and enables highly accurate thermal displacement correction. Become. In addition, by incorporating the level 70 at the rotation center C of the turntable 60, it becomes difficult to be affected by thermal deformation of the turntable 60, and the inclination angle of the rotation axis B of the turntable 60 with respect to the vertical axis is measured with high accuracy. However, the level 70 may be built in a place other than the rotation center C of the turntable 60.

  The control device 80 controls the spindle motor 41 to rotate the tool 42 and controls the X-axis motor 11c, the Z-axis motor 12c, the Y-axis motor 23c, and the B-axis motor 61 to control the workpiece W and the tool 42. Are moved relative to each other about the X-axis direction, the Z-axis direction, the Y-axis direction and the B-axis. In addition, the control device 80 includes a thermal displacement correction device 90 that performs thermal displacement correction by calculating the inclination angle of the rotation axis B of the turntable 60 with respect to the vertical axis associated with thermal deformation of the bed 10. However, the thermal displacement correction device 90 is not limited to the one provided inside the control device 80, and can also be applied as an external device.

(2. Explanation of thermal displacement correction)
Next, correction of thermal displacement by the thermal displacement correction device 90 will be described. The bed 10 tends to generate a temperature gradient due to a difference in heat capacity in the vertical direction, and the entire bed 10 is deformed when viewed from the X-axis direction in FIG. 1 due to a difference in thermal expansion between the upper surface and the lower surface of the bed 10. In the following description, only warping, which is one of the deformations seen from the X-axis direction, will be described. However, warping, which is one of the deformations seen from the Z-axis direction, can be corrected by a similar method. At this time, since the level 70 is also thermally deformed, the inclination angle of the rotation axis B of the turntable 60 cannot be accurately calculated with this level measurement value.

  In the machine tool 1 of the present embodiment, the machining reference is the rotation axis B of the turntable 60. Therefore, the level 70 is mounted on the turntable 60, and the turntable 60 is rotated so that the level measurement direction of the level 70 is aligned with the direction in which the thermal displacement correction is performed, for example, the Z-axis direction. This is because the level 70 can measure the level only in one direction. By measuring the level measurement value at each of the first angle when the turntable 60 is indexed in the direction in which the thermal displacement correction is performed and the second angle rotated 180 degrees from the first angle, Thermal deformation can be canceled. Therefore, the inclination angle of the rotation axis B of the turntable 60 with respect to the vertical axis associated with the thermal deformation of the bed 10 can be accurately calculated, and highly accurate thermal displacement correction can be performed.

  For example, as shown in FIG. 4A, the entire bed 10 is thermally deformed in the Z-axis direction, and when the turntable 60 is indexed at the first angle, the rotation axis B of the turntable 60 is the vertical axis V. It is assumed that the angle is inclined with respect to the angle θ. Furthermore, it is assumed that the level 70 itself is also thermally deformed, and the normal line L of the level 70 is inclined at an angle ε with respect to the rotation axis B of the turntable 60. The first level measurement value measured by the level 70 at this first angle is the tilt angle τ (= θ + ε). As shown in FIG. 4B, when the turntable 60 is indexed to a second angle obtained by rotating 180 degrees from the first angle, the rotation axis B of the turntable 60 is at an angle θ with respect to the vertical axis V. The normal line L of the level 70 is inclined by an angle ε in the direction opposite to the first angle with respect to the rotation axis B of the turntable 60. The second level measurement value measured by the level 70 at this second angle is the tilt angle φ (= θ−ε). Therefore, the inclination angle θ of the rotation axis B of the turntable 60 is represented by (τ + φ) / 2.

(3. Configuration of thermal displacement correction device)
Next, the thermal displacement correction device 90 will be described with reference to FIG. The thermal displacement correction device 90 includes an index control unit 91, a level measurement value acquisition unit 92, an inclination angle calculation unit 93, a correction value calculation unit 94, and a correction unit 95. Here, the index control unit 91, the level measurement value acquisition unit 92, the inclination angle calculation unit 93, the correction value calculation unit 94, and the correction unit 95 can be configured by individual hardware, respectively. It can also be configured to be realized by software.

  The index control unit 91 sends an index command for indexing the turntable 60 to a predetermined rotation angle to the control device 80, and controls an index signal indicating that the turntable 60 has been indexed to the predetermined rotation angle. Input from the device 80.

  The level measurement value acquisition unit 92 inputs the first level measurement value at the first angle from the level 70 when the signal for notifying that the turntable 60 is indexed at the first angle is input from the index control unit 91. To do. Further, when a signal notifying that the turntable 60 has been indexed to the second angle rotated 180 degrees from the first angle is input from the index control unit 91, the second level measurement value at the second angle is input from the level 70. Enter.

  The tilt angle calculation unit 93 receives the first and second level measurement values from the level measurement value acquisition unit 92 and obtains the tilt angle of the rotation axis B of the turntable 60 in which the thermal deformation of the level 70 is canceled.

  The correction value calculation unit 94 is based on the tilt angle of the rotation axis B of the turntable 60 calculated by the tilt angle calculation unit 93, that is, the command position of the tip of the rotary spindle 40, that is, each command of the column 20, the saddle 30 and the table 50. A correction value for the position is calculated. The command position is a value output for controlling each axis motor based on NC data input by the control device 80.

  The correction unit 95 corrects the command position (the command positions of the column 20, the saddle 30 and the table 50) at the tip of the rotation spindle 40 based on the correction value calculated by the correction value calculation unit 94.

(4. Processing by thermal displacement correction device)
Next, processing by the thermal displacement correction device 90 will be described with reference to FIG. The processing by the thermal displacement correction device 90 can be executed before or during processing.

  As shown in FIG. 3, the Z axis motor 12c is rotationally controlled to move the table 50 (step S1), and the table 50 is moved until the table 50 is positioned at the machining position (step S2: No). When the table 50 is positioned at the machining position (step S2: Yes), the B-axis motor 61 is rotationally controlled to rotate the turntable 60 (step S3), and the level measurement direction of the level 70 is the direction in which the thermal displacement correction is performed. Therefore, the turntable 60 is rotated until the turntable 60 is indexed at the first angle (step S4: No). If the level measurement direction of the level 70 coincides with the direction in which the thermal displacement correction is performed, the processes in steps 3 and 4 are not necessary. When the turntable 60 is indexed to the first angle (step S4: Yes), the first level measurement value at the first angle is acquired by the level 70 (step S5).

  Next, the B-axis motor 61 is rotationally controlled to rotate the turntable 60 (step S6), and the turntable 60 is rotated until the turntable 60 is indexed to a second angle rotated 180 degrees from the first angle ( Step S7: No). When the turntable 60 is indexed to the second angle (step S7: Yes), the second level measurement value at the second angle is acquired by the level 70 (step S8).

  Next, the inclination angle of the turntable 60 is obtained based on the first and second level measurement values (step S9). That is, the first level measurement value and the second level measurement value are added, and the sum is halved to obtain the inclination angle of the rotation axis B of the turntable 60.

  Then, based on the inclination angle of the rotation axis B of the turntable 60, a correction value for the command position at the tip of the rotation spindle 40 is calculated (step S10). And the command position of the front-end | tip of the rotation main shaft 40 is correct | amended with the calculated correction value (step S11). That is, the command position output from the control device 80 is corrected to the correction command position based on the correction value, and the thermal displacement correction program is terminated.

(5. Effect of thermal displacement correction processing)
As described above, according to the present embodiment, the table 50 is positioned at the machining position in steps S1 to S2. When the bed 10 warps in a concave shape when viewed from the X-axis direction in FIG. 1 due to thermal deformation, the inclination angle of the rotation axis B of the turntable 60 varies depending on the movement position of the table 50. Therefore, by moving the table 50 to the actual machining position and measuring the tilt angle of the rotation axis B of the turntable 60, high-precision machining is possible.

  Further, in the first and second level measurement value acquisition processes of steps S3 to S8, the first angle and the first angle were rotated 180 degrees from the level 70 built in the turntable 60 supported by the bed 10. The first and second level measurement values are obtained as the measurement angle of the level with respect to the vertical axis at the second angle. Thereby, in the inclination angle calculation process of step S9, the inclination angle of the rotation axis B of the turntable 60 with respect to the vertical axis in which the thermal deformation of the level 70 is canceled is obtained based on the first and second level measurement values. it can. Therefore, even if the bed 10 is thermally deformed, the thermal displacement can be corrected with high accuracy.

(6. Modification of processing by thermal displacement correction device)
Next, a modification of the processing by the thermal displacement correction device 90 will be described with reference to FIG. 5 shown corresponding to FIG. In FIG. 5, the same processes as those shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted. The processing by the thermal displacement correction device 90 can be executed before or during processing.

  As shown in FIG. 5, the rotation of the Z-axis motor 12c is controlled to position the table 50 at the machining position (steps S1 and S2), and the rotation of the B-axis motor 61 is controlled to index the turntable 60 to the first angle. (Steps S3 and S4), the first level measurement value at the first angle is acquired by the level 70 (Step S5). Next, the B-axis motor 61 is rotationally controlled to index the turntable 60 to the second angle (steps S6 and S7), and the second level measurement value at the second angle is acquired by the level 70 (step S8).

  Further, the rotation of the B-axis motor 61 is controlled to again index the turntable 60 to the first angle (steps S21 and S22), and the first level measurement value at the first angle is obtained again by the level 70 (step S23). . Then, it is determined whether or not the difference between the first level measurement value acquired in step S5 and the first level measurement value acquired in step S23 is equal to or less than an allowable value (step S24). When the difference from the first level measurement value exceeds the allowable value, the process returns to step S6 and the above-described processing is executed. On the other hand, when the difference from the first level measurement value is equal to or less than the allowable value in step S24, the turntable is based on the first level measurement value acquired in step S23 and the second level measurement value acquired in step S8. The inclination angle of 60 rotation axes B is obtained (step S9).

  Then, based on the inclination angle of the rotation axis B of the turntable 60, a correction value for the command position at the tip of the rotation spindle 40 is calculated (step S10). And the command position of the front-end | tip of the rotation spindle 40 is correct | amended with the calculated correction value (step S11), and a thermal displacement correction program is complete | finished. According to the above processing, since the first level measurement value is measured again, more accurate thermal displacement correction can be performed.

(7. Modifications)
In the above-described embodiment, the case where the thermal displacement correction method is applied to the turntable 60 that rotates around the vertical axis of the horizontal machining center has been described. Furthermore, the present invention can be similarly applied to a main shaft that rotates around a vertical axis of a vertical lathe. In addition, the present invention can be similarly applied to a machine tool including a rotating body (a rotating body having a rotating shaft that faces in a direction other than the horizontal axis direction) that rotates around a rotation axis that intersects the horizontal axis.

1: Machine tool 10: Bed, 11a, 11b: X-axis guide rail, 11c: X-axis motor 12a, 12b: Z-axis guide rail, 12c: Z-axis motor 20: Column, 21a, 21b: X-axis guide groove, 22a , 22b: Ball guide 23a, 23b: Y-axis guide rail, 23c: Y-axis motor 30: Saddle, 31a, 31b: Y-axis guide groove 40: Rotating spindle, 41: Spindle motor, 42: Tool 50: Table 60: Turn Table: 61: B-axis motor 70: Leveling device 80: Control device 90: Thermal displacement correction device 91: Indexing control unit 92: Level measurement value acquisition unit 93: Inclination angle calculation unit 94: Correction value calculation unit 95: Correction unit

Claims (6)

A thermal displacement correction for a machine tool comprising: a movable body that can move relative to a base of a machine tool; and a rotary body that rotates about a rotational axis that intersects a horizontal axis that is supported by the base or the movable body. In the method
A first level measurement value is obtained as a measurement angle of the level with respect to the vertical axis at a first angle in a state where a level measurement direction of a level built in the rotating body coincides with a direction in which thermal displacement correction is performed. 1 level measurement value acquisition process,
A second angle indexing step of indexing the rotating body to a position rotated 180 degrees from the first angle;
A second level measurement value acquisition step of acquiring a second level measurement value as a measurement angle of the level with respect to the vertical axis at the second angle by the level;
An inclination angle calculating step for obtaining an inclination angle of the rotation axis of the rotating body with respect to the vertical axis based on the first and second level measurement values;
A correction value calculation step for obtaining a correction value for the command position of the moving body of the machine tool by the NC program based on the tilt angle;
A correction step of correcting the command position by the correction value;
A thermal displacement correction method for a machine tool comprising: In claim 1,
In the thermal displacement correction method for the machine tool, when the level measurement direction of the spirit level does not coincide with the direction for performing thermal displacement correction, the rotation to the first angle as the direction for performing thermal displacement correction is performed. A first angle indexing step for indexing the body,
The first level measurement value acquisition step includes a machine tool that acquires a first level measurement value as a measurement angle of the level with respect to the vertical axis at the first angle calculated in the first angle indexing step. Thermal displacement correction method. In claim 1 or 2,
The rotating body is a thermal displacement correction method for a machine tool having a rotation axis in the vertical axis direction. In any one of Claims 1-3,
The level is a method for correcting a thermal displacement of a machine tool built in a rotation center of the rotating body. In any one of Claims 1-4,
A machining position moving step of moving the movable body to a machining position,
The level measurement value acquisition means is a thermal displacement correction method for a machine tool in which the first level measurement value is acquired after the movable body is indexed to the first angle at the machining position. A thermal displacement correction for a machine tool comprising: a movable body that can move relative to a base of a machine tool; and a rotary body that rotates about a rotational axis that intersects a horizontal axis that is supported by the base or the movable body. In the device
A level built in the rotating body;
The level measurement direction of the level is indexed to a second angle rotated by 180 degrees from the first angle in a state that coincides with the direction in which the thermal displacement correction is performed, and the level measurement direction of the level is the thermal displacement correction. If it does not coincide with the direction to be performed, the rotary body is indexed to the first angle as the direction for performing the thermal displacement correction, and the second angle rotated 180 degrees from the indexed first angle Index control means for performing index control,
Level measurement value acquisition means for acquiring first and second level measurement values by the level as measurement angles of the level relative to the vertical axis at the first and second angles;
An inclination angle calculating means for obtaining an inclination angle of the rotation axis of the rotating body with respect to the vertical axis based on the first and second level measurement values acquired by the level measurement value acquisition means;
Correction value calculation means for obtaining a correction value for the command position of the moving body of the machine tool by an NC program based on the tilt angle calculated by the tilt angle calculation means;
Correction means for correcting the command position based on the correction value calculated by the correction value calculation means;
A thermal displacement correction device for a machine tool comprising:

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