Method for calculating correction parameters for motion error in machine tool, machine tool

Abstract

To correct a motion error of a machine tool by appropriately measuring it without using any special measuring instrument.SOLUTION: A calculation method of a corrected parameter of a motion error in a machine tool is characterized by executing: a first measurement step (S2) of measuring three measuring surfaces A to C of a right-angle reference device by a touch probe; a second squareness calculation step (S3) of calculating respectively, first squareness from measured results of the measuring surface A and the measuring surface B and second squareness from the measured results of the measuring surface A and the measuring surface C; a difference calculation step (S4) of calculating a difference of the two pieces of squareness; a determination step (S5) of comparing the difference and a difference threshold; a step (S6) of calculating an average value of the two pieces of squareness when the difference is less than the difference threshold; squareness identification steps (S8 and S9) of when the difference exceeds the difference threshold, calculating an angular deviation of a translational axis and calculating corrected squareness based on the angular deviation, the first squareness and the second squareness; and a corrected parameter setup step (S10) of setting up a corrected parameter based on the average value or the corrected squareness.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a method for calculating a correction parameter for correcting a motion error in a machine tool, and the machine tool. [Background technology]

[0002] 1 is a schematic diagram of a machining center M, which is an example of a machine tool having three translational axes. The machining center M has a spindle head 2 capable of holding and rotating a tool, and a table 3 for holding a workpiece. The spindle head 2 has two translational axes, Z-axis and X-axis, which are perpendicular to each other, allowing for two degrees of freedom of translational movement relative to the bed 1. The table 3 has one degree of freedom of translational movement relative to the bed 1, due to the translational axis, Y-axis, which is perpendicular to the Z-axis and X-axis. Each translational axis is driven by a servo motor controlled by a numerical control device, which rotates a tool attached to the spindle head 2 and machines a workpiece fixed to the table 3 into any shape. Motion errors of machine tools include positioning errors, straightness, angular deviations (pitch, yaw, roll), and squareness, which are described in Non-Patent Document 1. These motion errors are transferred to the shape of the workpiece and become the cause of shape and dimensional errors of the workpiece. It is difficult in terms of cost and technology to reduce these motion errors and achieve high accuracy at the manufacturing and assembly stage of the machine, so compensation techniques have been developed to drive each axis while taking the motion errors into account. In order to correct and control the motion error, it is necessary to measure and calculate the motion error. In addition, since the motion error changes, it is important to be able to measure it periodically and without using special measuring equipment.

[0003] Non-Patent Document 1 proposes a method for measuring and evaluating a motion error. For example, when measuring an angle deviation, a method using a precision level or an optical angle deviation measuring instrument is described. Also, when measuring a squareness, a method using a straightedge, a square ruler, and a dial gauge is described. Non-Patent Document 2 describes a measuring instrument that can simultaneously measure positioning error, straightness, and angle deviation using a laser. Furthermore, Patent Document 1 proposes a method of using a step gauge having a plurality of blocks with a known distance between the blocks, changing the orientation of the step gauge in a plurality of directions, measuring the distance between the blocks in each direction, and measuring and calculating the positioning error of the translation axis and the squareness between the translation axes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-101279 A [Non-patent literature]

[0005] [Non-Patent Document 1] "Japanese Industrial Standards JIS B 6336-2: 2002", [Retrieved July 14, 2021], Internet<https: / / kikakurui.com / b6 / B6336-2-2002-01.html> [Non-Patent Document 2] "XM-60 / XM-600 Multi-Axis Calibrator", Renishaw, [Retrieved July 14, 2021], Internet<https: / / www.renishaw.jp / jp / xm-60-and-xm-600-multi-axis-calibrator--39258> Summary of the Invention [Problem to be solved by the invention]

[0006] When measuring squareness using the method described in Non-Patent Document 1 or Patent Document 1, there is a problem that the squareness varies depending on the measured position due to the influence of a large angular deviation of the translation axis, and is not uniquely determined. Furthermore, even if a correction parameter is calculated based on the measured squareness and a command value is corrected, there is a problem that the shape and dimensional errors of the workpiece are not improved. On the other hand, to eliminate the effect of the angular deviation of the translation axis, it is necessary to measure and correct the angular deviation, but this poses a problem in that special measurements such as those described in Non-Patent Documents 1 and 2 are required for the measurement.

[0007] Therefore, an object of the present disclosure is to provide a method for calculating correction parameters for motion errors in a machine tool, and a machine tool that is capable of appropriately measuring and correcting the motion errors of the machine tool without using special measuring instruments. [Means for solving the problem]

[0008] In order to achieve the above object, a first configuration of the present disclosure is a method for calculating the compensation parameters in a machine tool having a table for holding a workpiece, a spindle for holding a tool, and three or more translational axes, the spindle being capable of relative translational motion with three or more degrees of freedom relative to the table, and capable of compensating for motion errors of the translational axes in accordance with predetermined compensation parameters, the method having a predetermined measurement surface A, and measurement surfaces B and C which are perpendicular to measurement surface A and parallel to each other, the angle between measurement surface A and measurement surface B and the angle between measurement surface A and measurement surface C being known, using a rectangular standard device, a first measurement step of placing the right-angle standard on the table and measuring the measurement surface A, the measurement surface B, and the measurement surface C of the right-angle standard by a position measurement sensor attached to the spindle; a first perpendicularity calculation step of calculating a first perpendicularity between the measurement surface A and the measurement surface B from a measurement result of the measurement surface A and the measurement surface B in the first measurement step; a second perpendicularity calculation step of calculating a second perpendicularity between the measurement surface A and the measurement surface C from the measurement results of the measurement surface A and the measurement surface C in the first measurement step; a difference calculation step of calculating a difference between the first perpendicularity and the second perpendicularity; a determination step of comparing the difference with a preset difference threshold; a perpendicularity identifying step of calculating an average value of the first perpendicularity and the second perpendicularity when the difference is equal to or less than the difference threshold, and calculating an angle deviation of the translation axis and calculating a corrected perpendicularity based on the angle deviation and the first perpendicularity or the second perpendicularity when the difference is greater than the difference threshold; and a correction parameter setting step of setting the correction parameter based on the average value or the corrected perpendicularity. Another aspect of the first configuration of the present disclosure is characterized in that, in the above configuration, if the difference exceeds the difference threshold value in the determination step, the squareness identification step installs the squareness standard device at a plurality of positions, and performs the first measurement step, the first squareness calculation step, the second squareness calculation step, and the difference calculation step again at each of the positions, and calculates the angle deviation based on the obtained plurality of differences. In order to achieve the above object, a second configuration of the present disclosure is a method for calculating the compensation parameters in a machine tool having a table for holding a workpiece, a spindle for holding a tool, and three or more translational axes, the spindle being capable of relative translational motion with three or more degrees of freedom relative to the table, and capable of compensating for motion errors of the translational axes in accordance with predetermined compensation parameters, the method comprising the steps of: calculating the compensation parameters using a rectangular standard device having a predetermined measurement surface A and a measurement surface B perpendicular to the measurement surface A and having a known angle between the measurement surface A and the measurement surface B; a first measurement step of placing the right-angle standard on the table and measuring the measurement surface A and the measurement surface B of the right-angle standard with a position measurement sensor attached to the spindle; a second measurement step of changing the orientation of the right-angle standard and measuring the measurement surface A and the measurement surface B with the position measurement sensor; a first perpendicularity calculation step of calculating a first perpendicularity between the measurement surface A and the measurement surface B from a measurement result of the measurement surface A and the measurement surface B in the first measurement step; a second perpendicularity calculation step of calculating a second perpendicularity between the measurement surface A and the measurement surface B from the measurement results of the measurement surface A and the measurement surface B in the second measurement step; a difference calculation step of calculating a difference between the first perpendicularity and the second perpendicularity; a determination step of comparing the difference with a preset difference threshold; a perpendicularity identifying step of calculating an average value of the first perpendicularity and the second perpendicularity when the difference is equal to or less than the difference threshold, and calculating an angle deviation of the translation axis and calculating a corrected perpendicularity based on the angle deviation and the first perpendicularity or the second perpendicularity when the difference is greater than the difference threshold; and a correction parameter setting step of setting the correction parameter based on the average value or the corrected perpendicularity. Another aspect of the second configuration of the present disclosure is characterized in that, in the above configuration, if the difference exceeds the difference threshold value in the determination step, the squareness identification step installs the squareness standard device at a plurality of positions, and performs the first measurement step, the second measurement step, the first squareness calculation step, the second squareness calculation step, and the difference calculation step again at each of the positions, and calculates the angle deviation based on the obtained plurality of differences. In order to achieve the above object, a third configuration of the present disclosure is a machine tool having a table for holding a workpiece, a spindle for holding a tool, and three or more translational axes, the spindle being capable of translational motion with three or more degrees of freedom relative to the table, and capable of compensating for motion errors of the translational axes in accordance with predetermined compensation parameters, a first measuring means for measuring the measurement surface A, the measurement surface B, and the measurement surface C, which are perpendicular to the measurement surface A and parallel to each other, with a right-angle standard having a known angle between the measurement surface A and the measurement surface B and the angle between the measurement surface A and the measurement surface C being placed on the table, and the first measuring means for measuring the measurement surface A, the measurement surface B, and the measurement surface C of the right-angle standard with a position measuring sensor attached to the main spindle, a first perpendicularity calculation means for calculating a first perpendicularity from a measurement result of the measurement surface A and the measurement surface B by the first measurement means; a second perpendicularity calculation means for calculating a second perpendicularity from a measurement result of the measurement surface A and the measurement surface C by the first measurement means; A difference calculation means for calculating a difference between the first perpendicularity and the second perpendicularity; A determination means for comparing the difference with a preset difference threshold value; a perpendicularity identification means for calculating an average value of the first perpendicularity and the second perpendicularity when the difference is equal to or less than the difference threshold value, and for calculating an angle deviation of the translation axis and calculating a corrected perpendicularity based on the angle deviation and the first perpendicularity or the second perpendicularity when the difference exceeds the difference threshold value; and a correction parameter setting means for setting the correction parameter based on the average value or the corrected perpendicularity. In order to achieve the above object, a fourth configuration of the present disclosure is a machine tool having a table for holding a workpiece, a spindle for holding a tool, and three or more translational axes, the spindle being capable of translational motion with three or more degrees of freedom relative to the table, and capable of compensating for motion errors of the translational axes in accordance with predetermined compensation parameters, a first measuring means for measuring the measurement surfaces A and B of a right-angle standard having a predetermined measurement surface A and a measurement surface B perpendicular to the measurement surface A, with a right-angle standard having a known angle between the measurement surface A and the measurement surface B being set on the table, and using a position measuring sensor attached to the main spindle to measure the measurement surfaces A and B of the right-angle standard; a second measuring means for measuring the measurement surface A and the measurement surface B by changing the orientation of the right-angle standard with the position measuring sensor; a first perpendicularity calculation means for calculating a first perpendicularity from a measurement result of the measurement surface A and the measurement surface B by the first measurement means; a second perpendicularity calculation means for calculating a second perpendicularity from a measurement result of the measurement surface A and the measurement surface B by the second measurement means; A difference calculation means for calculating a difference between the first perpendicularity and the second perpendicularity; A determination means for comparing the difference with a preset difference threshold value; a perpendicularity identification means for calculating an average value of the first perpendicularity and the second perpendicularity when the difference is equal to or less than the difference threshold value, and for calculating an angle deviation of the translation axis and calculating a corrected perpendicularity based on the angle deviation and the first perpendicularity or the second perpendicularity when the difference exceeds the difference threshold value; and a correction parameter setting means for setting the correction parameter based on the average value or the corrected perpendicularity. Effect of the Invention

[0009] According to the present disclosure, by measuring three or two measurement surfaces of a right-angle standard device serving as a precision master with a position measurement sensor, a correction parameter for a motion error can be obtained without using a special measuring device. Therefore, the motion error of the machine tool can be appropriately corrected based on the obtained correction parameter. In addition, it is easy to determine whether the angular deviation of the translation axis has a negative effect on the measured squareness. Furthermore, even if the angular deviation of the translation axis is large and the squareness cannot be uniquely determined, it is possible to measure the angular deviation of the translation axis and obtain the correction parameter. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a machining center having X-, Y-, and Z-axis translation axes. [Diagram 2] FIG. 2 is a functional block diagram of a numerical control device. [Diagram 3] FIG. 2 is a block diagram showing a control configuration of the machining center. [Figure 4] 13 is a flowchart of a method for calculating correction parameters. [Diagram 5] 11 is a flowchart for measuring an angle deviation. [Figure 6] This is an example of a right-angle standard. [Figure 7] 4 is an example of parameters of a right-angle standard. [Figure 8] FIG. 1 is a schematic diagram of a touch probe and a right-angle standard installed on a table. [Figure 9]FIG. 13 is a schematic diagram showing an example of installation of a right-angle standard when performing measurements by changing the installation position of the right-angle standard. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Here, a case where the perpendicularity between the X and Y axes and the angle deviation (yaw) of the Y axis are measured and corrected will be described as an example. As an example of a machine tool to which the present invention is applied, a machining center M shown in Fig. 1 will be described. Fig. 2 is a functional block diagram of a numerical control device 21. In the numerical control device 21, when a machining program 11 is input, a command value generating means 12 generates a command value for each translation axis. Based on the generated command value, a correction value for each axis is calculated by correction value calculation means 16, and the sum of the command value and the correction value is sent to servo command value conversion means 13 to calculate a servo command value. The calculated servo command value for each axis is sent to servo amplifiers 14a-14c for each axis. Servo amplifiers 14a-14c for each axis drive servo motors 15a-15c for each axis, respectively, to control the relative position of spindle head 2 with respect to table 3.

[0012] 3, the numerical control device 21 has a recording means 22, which can store the compensation parameters, the reference device conditions, a calculation program for the compensation parameters, a compensation program for the motion error, etc. It also has a display means 23 for transmitting information to an operator, an input means 24 for inputting the measurement target, etc., and a receiver 25 for the detection signal of the touch probe 101, which will be described later. The correction parameters on which the correction values ​​are based are recorded in the recording means 22, and in the case of the perpendicularity between the X and Y axes, or the Y-axis angular deviation (yaw), the Y-axis position and the angular deviation at that position are stored as point cloud data. The angular deviation between each point is calculated by interpolating using linear interpolation or the like. If the perpendicularity between the X and Y axes is γxy and the Y-axis angular deviation (yaw) is EAY(i), the correction value can be calculated using the following equation 1. [Number 1] ΔCx = γxy(Y-Yk) ΔCy = EAY(i)(X-Xk) Here, ΔCx and ΔCy are the X-axis and Y-axis correction values, X and Y are the X-axis and Y-axis command values, and Xk and Yk are the X-axis and Y-axis correction reference positions, respectively.

[0013] Next, a method of calculating the correction parameters executed by the numerical control device 21 will be described with reference to the flowchart of Fig. 4. The numerical control device 21 functions as a first measuring means, a second measuring means, a first perpendicularity calculating means, a second perpendicularity calculating means, a difference calculating means, a determining means, a perpendicularity identifying means, and a correction parameter setting means of the present disclosure. First, the operator inputs a measurement error through the input means 24. This input is for making the numerical control device 21 recognize what kind of error is to be measured. FIG. 6 shows an example of a right-angle standard G used for error measurement. The input measurement error includes measurement points (P 100 ~P 114 ) calibration value data is linked. First, in step (hereinafter referred to as "S") 1, the operator places the rectangular standard G on the table 3 so that the measurement surface A is parallel to the Y axis, as shown in Fig. 8, and attaches the touch probe 101 to the spindle head 2 and positions it so that it is directly above the origin of the rectangular standard. The touch probe 101 has a stylus at its tip, and transmits a signal the moment the stylus comes into contact with the object to be measured. When the numerical control device 21 receives the signal at the connected receiver 25, it measures the position by taking the positions of each axis at that time as the contact positions.

[0014] Next, in S2, the measurement point (P 100 ~P 114 ) is measured (first measurement step). 100 ~P 104 At each measurement point, the stylus is brought into contact with the measurement surface from the Y direction to measure the Y direction position at each measurement point. 105 ~P 109 At each measurement point, the stylus is brought into contact with the measurement surface C from the X direction to measure the X direction position at each measurement point. 110 ~P114 ) the stylus is brought into contact from the Y direction and the Y direction position at each measurement point is measured. Next, in S3, the perpendicularity is calculated (first perpendicularity and second perpendicularity calculation step). 100 ~P 104 ) and measurement point (P 110 ~P 114 ) and the measured Y-direction position (My 100 ~My 104 ), (My 110 ~My 114 ) and the X-axis command value of each point, the slopes a2 and a3 are calculated by the least squares method or the like. Next, the measurement points (P 105 ~P 109 ), the measured X-direction position (Mx 105 ~Mx 109 ) and the Y-axis command value of each point, the inclination a1 is calculated by the least squares method or the like. Then, the perpendicular angles γxy1 and γxy2 are calculated by the following equation 2. [Number 2] γxy1=a2-a1 γxy2=a3-a1

[0015] Next, in S4, a squareness difference Δγxy is calculated by the following Equation 3 (difference calculation step). [Number 3] Δγxy=γxy2-γxy1 Next, in S5, the calculated squareness difference is compared with a difference threshold value previously recorded in the recording means 22 (determination step). If it is determined in S5 that the squareness difference is equal to or smaller than the difference threshold value, in S6, an average value γxy' of squareness γxy1 and γxy2 is calculated (squareness identification step).

[0016] On the other hand, if it is determined in S5 that the squareness difference is greater than the difference threshold value, the display means 23 displays the necessity of measuring the angle deviation in S7. Next, in S8, the angular deviation (yaw) is measured. The details of the angular deviation measurement will be described later. Next, in S9, a squareness γxy″ (corrected squareness) taking the angle deviation into consideration is calculated from the angle deviation (yaw) EAY(i) calculated in S8 and the squareness γxy1 calculated in S3 using the following Equation 4 (S7 to S9: squareness identification step). [Number 4] Δγxy = γxy1 - EAY(Py 100 ) Here, EAY(Py 100 ) is the measurement point P of the right-angle standard G at S2. 100 is the angular deviation at the Y-axis position when the measurement was performed. Next, in S10, either the average value γxy' of the squareness obtained in S6 or the squareness γxy'' obtained in S9 is set as a correction parameter (correction parameter setting step). The acquired correction parameters are recorded in the recording means 22 and are used in the calculation of the correction values ​​(eg, Equation 1 above) in the correction value calculation means 16 in FIG.

[0017] Next, the measurement of the angle deviation in S8 will be described with reference to the flowchart shown in FIG. First, in S8-2, the position for installing the right-angle standard G is displayed on the display means 23. The installation position to be displayed is, for example, as shown in Fig. 9, and the user is prompted to install the right-angle standard G at installation position 1. Next, in S8-3, the operator installs the rectangular standard G on the table 3 in accordance with the displayed installation position, and positions the touch probe 101 directly above the rectangular standard origin. Next, in S8-4, the three measurement surfaces A to C of the right-angle standard G are measured by the method explained in S2. Next, in S8-5, the two square angles γxy3 and γxy4 are calculated by the method described in S3, and the square angle difference Δγxy(Y1) is calculated by the method described in S4. The installation positions 2 to 5 of the square angle standard device G are changed to repeat S8-2 to S8-5. Next, in S8-7, the angular deviation (yaw) is calculated from the obtained Δγxy(Y1) to Δγxy(Y5) by the following Equation 5. [Number 5] EAY(i) = ΣΔγxy(i)

[0018] In this manner, in the above-described method for calculating the correction parameters for the motion error and in the machining center M, the three measurement surfaces A to C of the right-angle standard G, which serves as the precision master, are measured with a touch probe 101 (position measurement sensor) attached to the spindle head 2 (spindle), two squareness angles are calculated from the measurement results, the difference between the two is calculated, the squareness angle is identified based on the results of comparing the difference with a difference threshold value, and the correction parameters are set based on the identified squareness angle. This configuration makes it possible to obtain the correction parameters for the motion error without using a special measuring device. Therefore, it is possible to appropriately correct the motion error of the machining center M based on the obtained correction parameters. In addition, from the comparison result between the difference between the two squarenesses and the difference threshold value, it is possible to easily determine whether the angular deviation of the translation axis has a negative effect on the measured squareness. Furthermore, even if the angular deviation of the translation axis is large and the squareness cannot be uniquely determined, it is possible to measure the angular deviation of the translation axis and obtain the correction parameters.

[0019] In the above embodiment, the present disclosure has been described using as an example a right-angle standard G having three measurement surfaces, namely, measurement surface A, measurement surface B, and measurement surface C. However, the present disclosure can also be applied when using a right-angle standard G having two measurement surfaces, namely, measurement surface A and measurement surface B. In this case, the machining center M performs the measurement, for example, in the following manner. First, a right-angle standard G is placed on the table 3, and a first measurement step is executed in which the measurement surfaces A and B of the right-angle standard G are measured with the touch probe 101 attached to the spindle head 2. Next, the orientation of the right-angle standard G is changed (for example, rotated 180 degrees around the X-axis) and set, and a second measurement step is performed in which measurement surface A and measurement surface B are measured with the touch probe 101. Next, a first perpendicularity calculation step is executed to calculate a first perpendicularity between measurement surface A and measurement surface B from the measurement results of measurement surface A and measurement surface B in the first measurement step, in the same manner as in the previous embodiment. Next, a second perpendicularity calculation step is executed to calculate a second perpendicularity between measurement surface A and measurement surface B from the measurement results of measurement surface A and measurement surface B in the second measurement step, in the same manner as in the previous embodiment. The subsequent processing is the same as in the previous embodiment. In this case as well, the motion error correction parameters can be obtained without using a special measuring device. Furthermore, the machine tool of the present disclosure is not limited to a machining center. [Explanation of symbols]

[0020] 1··bed, 2··spindle head, 3··table, 11··machining program, 12··command value generating means, 13··servo command value converting means, 14a to 14c··servo amplifier, 15a to 15c··servo motor, 16··correction value calculating means, 21··numerical control device, 22··recording means, 23··display means, 24··input means, 25··receiver, 101··touch probe, G··right-angle standard, M··machining center.

Claims

1. A method for calculating the compensation parameters in a machine tool having a table for holding a workpiece, a spindle for holding a tool, and three or more translational axes, the spindle being capable of translational motion with three or more degrees of freedom relative to the table, and capable of compensating for motion errors of the translational axes in accordance with predetermined compensation parameters, the machine tool having a predetermined measurement surface A, and measurement surfaces B and C which are perpendicular to measurement surface A and parallel to each other, the method comprising the steps of: a first measurement step of placing the rectangular standard on the table and measuring the measurement surface A, the measurement surface B, and the measurement surface C of the rectangular standard by a position measurement sensor attached to the spindle; a first perpendicularity calculation step of calculating a first perpendicularity between the measurement surface A and the measurement surface B from measurement results of the measurement surface A and the measurement surface B in the first measurement step; a second perpendicularity calculation step of calculating a second perpendicularity between the measurement surface A and the measurement surface C from measurement results of the measurement surface A and the measurement surface C in the first measurement step; a difference calculation step of calculating a difference between the first perpendicularity and the second perpendicularity; a determination step of comparing the difference with a preset difference threshold; a perpendicularity identifying step of calculating an average value of the first perpendicularity and the second perpendicularity when the difference is equal to or less than the difference threshold, and calculating an angle deviation of the translation axis and calculating a corrected perpendicularity based on the angle deviation and the first perpendicularity or the second perpendicularity when the difference is greater than the difference threshold; a correction parameter setting step of setting the correction parameter based on the average value or the corrected perpendicularity; A method for calculating a correction parameter for a motion error in a machine tool, comprising:

2. 2. The method for calculating a compensation parameter for a motion error in a machine tool according to claim 1, characterized in that, when the difference exceeds the difference threshold value in the determination step, the squareness identification step includes installing the squareness standard device at a plurality of positions, and performing the first measurement step, the first squareness calculation step, the second squareness calculation step, and the difference calculation step again at each of the positions, and calculating the angle deviation based on the obtained plurality of differences.

3. A method for calculating the compensation parameters in a machine tool having a table for holding a workpiece, a spindle for holding a tool, and three or more translational axes, the spindle being capable of translational motion with three or more degrees of freedom relative to the table, and capable of compensating for motion errors of the translational axes in accordance with predetermined compensation parameters, the method comprising the steps of: a first measurement step of placing the rectangular standard on the table and measuring the measurement surface A and the measurement surface B of the rectangular standard by a position measurement sensor attached to the main shaft; a second measurement step of changing the orientation of the right-angle standard and measuring the measurement surface A and the measurement surface B with the position measurement sensor; a first perpendicularity calculation step of calculating a first perpendicularity between the measurement surface A and the measurement surface B from measurement results of the measurement surface A and the measurement surface B in the first measurement step; a second perpendicularity calculation step of calculating a second perpendicularity between the measurement surface A and the measurement surface B from measurement results of the measurement surface A and the measurement surface B in the second measurement step; a difference calculation step of calculating a difference between the first perpendicularity and the second perpendicularity; a determination step of comparing the difference with a preset difference threshold; a perpendicularity identifying step of calculating an average value of the first perpendicularity and the second perpendicularity when the difference is equal to or less than the difference threshold, and calculating an angle deviation of the translation axis and calculating a corrected perpendicularity based on the angle deviation and the first perpendicularity or the second perpendicularity when the difference is greater than the difference threshold; a correction parameter setting step of setting the correction parameter based on the average value or the corrected perpendicularity; A method for calculating a correction parameter for a motion error in a machine tool, comprising:

4. 4. The method for calculating a compensation parameter for a motion error in a machine tool according to claim 3, characterized in that, when the difference exceeds the difference threshold value in the determination step, the squareness identification step includes installing the squareness standard device at a plurality of positions, and performing the first measurement step, the second measurement step, the first squareness calculation step, the second squareness calculation step, and the difference calculation step again at each of the positions, and calculating the angle deviation based on the obtained plurality of differences.

5. A machine tool having a table for holding a workpiece, a spindle for holding a tool, and three or more translational axes, the spindle being capable of translational motion with three or more degrees of freedom relative to the table, and capable of compensating for motion errors of the translational axes in accordance with predetermined compensation parameters, a first measuring means for measuring the measurement surface A, the measurement surface B, and the measurement surface C, which are orthogonal to the measurement surface A and parallel to each other, with a right-angle standard having known angles between the measurement surface A and the measurement surface B and between the measurement surface A and the measurement surface C, by a position measuring sensor attached to the main spindle, in a state where the right-angle standard is installed on the table; a first perpendicularity calculation means for calculating a first perpendicularity from a measurement result of the measurement surface A and the measurement surface B by the first measurement means; a second perpendicularity calculation means for calculating a second perpendicularity from a measurement result of the measurement surface A and the measurement surface C by the first measurement means; A difference calculation means for calculating a difference between the first perpendicularity and the second perpendicularity; A determination means for comparing the difference with a preset difference threshold value; a perpendicularity identification means for calculating an average value of the first perpendicularity and the second perpendicularity when the difference is equal to or less than the difference threshold value, and for calculating an angle deviation of the translation axis and calculating a corrected perpendicularity based on the angle deviation and the first perpendicularity or the second perpendicularity when the difference exceeds the difference threshold value; a correction parameter setting means for setting the correction parameter based on the average value or the corrected perpendicularity; A machine tool comprising:

6. A machine tool having a table for holding a workpiece, a spindle for holding a tool, and three or more translational axes, the spindle being capable of translational motion with three or more degrees of freedom relative to the table, and capable of compensating for motion errors of the translational axes in accordance with predetermined compensation parameters, a first measuring means for measuring the measurement surfaces A and B of a right-angle standard having a predetermined measurement surface A and a measurement surface B perpendicular to the measurement surface A, with a right-angle standard having a known angle between the measurement surface A and the measurement surface B being set on the table, and using a position measuring sensor attached to the main shaft to measure the measurement surfaces A and B of the right-angle standard; a second measuring means for measuring the measurement surface A and the measurement surface B by changing the orientation of the right-angle standard with the position measuring sensor; a first perpendicularity calculation means for calculating a first perpendicularity from a measurement result of the measurement surface A and the measurement surface B by the first measurement means; a second perpendicularity calculation means for calculating a second perpendicularity from a measurement result of the measurement surface A and the measurement surface B by the second measurement means; A difference calculation means for calculating a difference between the first perpendicularity and the second perpendicularity; A determination means for comparing the difference with a preset difference threshold value; a perpendicularity identification means for calculating an average value of the first perpendicularity and the second perpendicularity when the difference is equal to or less than the difference threshold value, and for calculating an angle deviation of the translation axis and calculating a corrected perpendicularity based on the angle deviation and the first perpendicularity or the second perpendicularity when the difference exceeds the difference threshold value; a correction parameter setting means for setting the correction parameter based on the average value or the corrected perpendicularity; A machine tool comprising:

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