Numerical control device and control method

Abstract

To correct a dynamic error with good accuracy, without using a sensor.SOLUTION: A numerical control device which makes a machine tool perform cutting at an instruction coordinate value shown by a cutting instruction received from instruction analyzing means, comprises: measurement means that makes the machine tool airborne-measure a shape of a cut test work-piece, and obtains measurement data showing the measured shape of the test work-piece; dynamic correction parameter calculation means that calculates a dynamic correction parameter for correcting a dynamic error generated by force acting on the machine tool and speed in cutting, on the basis of an instruction form shown by the cutting instruction and the measurement data obtained by the measurement means; and dynamic correction means that corrects the dynamic error with respect to the instruction coordinate value on the basis of the calculated dynamic correction parameter. The dynamic correction parameter calculation means obtains only the dynamic error through a comparison of the instruction form with the measurement data, and calculates the dynamic correction parameter form the obtained dynamic error.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a numerical control device and a control method. [Background technology]

[0002] An error occurs between the shape of the machined workpiece and the designed shape due to the rigidity and thermal deformation of the machine tool, or the deflection of the tool, etc. Therefore, there is a method in which the shape of the machined workpiece is measured in advance using a laser interferometer, autocollimator, level, etc., and correction is made based on the measured error. However, the above-mentioned correction method only corrects static errors, and it is difficult to correct dynamic errors that occur during cutting. Dynamic errors are errors caused by the forces and speeds acting on the machine tool, such as errors caused by squareness errors of the machine tool and tool deflection that occur in areas with low rigidity due to cutting point loads. In this regard, there is a known technology that uses a sensor to detect the pressure caused by tool deflection and corrects the amount of tool deflection based on the detected pressure, thereby enabling high-precision machining even in high-speed cutting (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-318283 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in order to correct the amount of deflection of the tool, a separate sensor must be prepared and attached to the machine tool, which is costly. Furthermore, it is difficult to calculate the relationship between the cutting point load and the deviation of the machining result, which is the basis for calculating the correction amount.

[0005] Therefore, it is desired to accurately correct the dynamic error without using a sensor. [Means for solving the problem]

[0006] (1) One aspect of the numerical control device disclosed herein is a numerical control device that causes a machine tool to cut using command coordinate values ​​indicated by a cutting command received from a command analysis means, and includes: a measurement means that causes the machine tool to measure the shape of a cut test workpiece on-machine and acquires measurement data indicating the measured shape of the test workpiece; a dynamic compensation parameter calculation means that calculates, based on the command shape indicated by the cutting command and the measurement data acquired by the measurement means, a dynamic compensation parameter that compensates for dynamic errors caused by the forces and speeds acting on the machine tool during cutting; and a dynamic compensation means that corrects the dynamic errors for the command coordinate values ​​based on the calculated dynamic compensation parameters, wherein the dynamic compensation parameter calculation means acquires only the dynamic errors by comparing the command shape with the measurement data and calculates the dynamic compensation parameters from the acquired dynamic errors.

[0007] (2) One aspect of the control method of the present disclosure is a control method executed by a computer to cause a machine tool to cut using command coordinate values ​​indicated by a cutting command received from a command analysis means, the control method comprising: a measurement step of causing the machine tool to measure the shape of a cut test workpiece on-machine and acquiring measurement data indicating the measured shape of the test workpiece; a dynamic compensation parameter calculation step of calculating, based on the command shape indicated by the cutting command and the acquired measurement data, dynamic compensation parameters that compensate for dynamic errors caused by the forces and speeds acting on the machine tool during cutting; and a dynamic compensation step of correcting the dynamic errors relative to the command coordinate values ​​based on the calculated dynamic compensation parameters, wherein the dynamic compensation parameter calculation step acquires only the dynamic errors by comparing the command shape with the measurement data and calculates the dynamic compensation parameters from the acquired dynamic errors. [Effects of the Invention]

[0008] According to one aspect, dynamic errors can be corrected with high accuracy without using a sensor. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a functional block diagram showing an example of the functional configuration of a numerical control device according to a first embodiment. [Figure 2] FIG. 1 is a diagram illustrating an example of a machine tool. [Figure 3A] FIG. 10 is a diagram illustrating an example of a squareness error. [Figure 3B] FIG. 10 is a diagram showing an example of an error caused by deflection of a tool. [Figure 4] FIG. 10 is a diagram showing an example of cutting a test workpiece with a machine tool. [Figure 5] FIG. 10 is a diagram showing an example of the amount of deviation when a cutting point load is also applied in the circumferential direction. [Figure 6] FIG. 10 is a diagram illustrating an example of a relationship between a dynamic compensation parameter and a machine tool. [Figure 7] FIG. 10 is a diagram illustrating an example of dynamic correction parameters for squareness error. [Figure 8] FIG. 10 is a diagram showing an example of best fitting a circle to measurement data. [Figure 9] FIG. 10 is a diagram showing an example of the direction of a cutting point load. [Figure 10] FIG. 10 is a diagram illustrating an example of correction of an error due to deflection of a tool. [Figure 11] 1 is a diagram illustrating an example of a numerical control device according to a first embodiment. [Figure 12] 1 is a diagram illustrating an example of a numerical control device according to a first embodiment. [Figure 13] FIG. 10 is a diagram illustrating an example of correction of an error due to deflection of a tool. [Figure 14] FIG. 10 is a functional block diagram showing an example of a functional configuration of a numerical control device according to a second embodiment that is added to the numerical control device according to the first embodiment. [Figure 15A] 10A and 10B are diagrams illustrating an example of interpolation processing by a dynamic correction parameter interpolation means. [Figure 15B]10A and 10B are diagrams illustrating an example of interpolation processing by a dynamic correction parameter interpolation means. [Figure 16] FIG. 10 is a diagram illustrating an example of interpolating a plurality of dynamic correction parameters using an M-th order function. [Figure 17] FIG. 10 is a functional block diagram showing an example of a functional configuration of a numerical control device according to a third embodiment that is added to the numerical control device according to the first embodiment. [Figure 18A] FIG. 10 is a diagram illustrating an example in which the tool is circularly moved clockwise. [Figure 18B] FIG. 10 is a diagram illustrating an example in which the tool is circularly moved counterclockwise. DETAILED DESCRIPTION OF THE INVENTION

[0010] First Embodiment First, an overview of this embodiment will be described. In this embodiment, a numerical control device cuts a test workpiece (described later) into a predetermined shape, causes a machine tool to measure the shape of the cut test workpiece on-machine, and acquires measurement data indicating the measured shape of the test workpiece. Based on the command shape indicated by the cutting command and the acquired measurement data, the numerical control device calculates dynamic compensation parameters that compensate for dynamic errors caused by forces and speeds acting on the machine tool during cutting. The numerical control device compensates for dynamic errors with respect to command coordinate values ​​based on the calculated dynamic compensation parameters.

[0011] As a result, according to this embodiment, it is possible to solve the problem of "accurately correcting dynamic errors without using a sensor that detects pressure due to tool deflection." The above is an outline of this embodiment.

[0012] Next, the configuration of this embodiment will be described in detail with reference to the drawings.

[0013] 1 is a functional block diagram showing an example of the functional configuration of a numerical control device according to the first embodiment. Note that a description from the perspective of a control method will be omitted because it can be explained by replacing "means" with "steps."

[0014] The numerical control device 10 may be directly connected to the machine tool 20 via a connection interface (not shown). The numerical control device 10 and the machine tool 20 may also be connected to each other via a network (not shown) such as a LAN (Local Area Network) or the Internet. In this case, the numerical control device 10 and the machine tool 20 are provided with a communication unit (not shown) for communicating with each other via such a connection.

[0015] <Machine tools 20> The machine tool 20 is a known orthogonal three-axis machine tool in which the spindle head moves in the X-axis, Y-axis, and Z-axis directions, and operates based on an operation command (cutting command) from the numerical control device 10. FIG. 2 is a diagram showing an example of a machine tool 20. As shown in FIG. As shown in FIG. 2, machine tool 20 is composed of table (surface plate) 21 arranged on the XY plane, support columns 22(1) and 22(2) provided in the vertical (Z-axis) direction at both ends of table 21, and support column 23 provided in the horizontal (X-axis) direction between support columns 22(1) and 22(2).

[0016] The spindle head 24 and the tool 25 attached to the spindle head 24 are moved in the X-axis direction relative to the support 23 by an X-axis servo motor 31, and are moved up and down in the Z-axis direction relative to the support 23 by a Z-axis servo motor 33. In addition, the gate formed by the support 22(1), 22(2), and the support 23 is moved in the Y-axis direction by a Y-axis servo motor 32.

[0017] <Numerical control device 10> The numerical control device 10 is a numerical control device known to those skilled in the art, and generates operation commands based on control information and transmits the generated operation commands to the machine tool 20. In this way, the numerical control device 10 controls the operation of the machine tool 20.

[0018] 1, the numerical control device 10 includes a storage unit 100 and a control unit 200. The control unit 200 further includes a measurement unit 210, a dynamic correction parameter calculation unit 220, a command analysis unit 230, a static correction unit 240, a dynamic correction unit 250, an interpolation unit 260, an X-axis acceleration / deceleration control unit 270, a Y-axis acceleration / deceleration control unit 280, and a Z-axis acceleration / deceleration control unit 290.

[0019] The storage unit 100 is a RAM (Random Access Memory), a HDD (Hard Disk Drive), or the like, and stores static error data 110 and dynamic correction parameter data 120.

[0020] The static error data 110 is, for example, a static error measured in advance in order to correct the static error acting on the machine tool 20 by the static correction means 240 described later.

[0021] The dynamic correction parameter data 120 is, for example, a dynamic correction parameter calculated by a dynamic correction parameter calculation means 220, which will be described later.

[0022] The control unit 200 includes a CPU, a ROM, a RAM, a CMOS memory, and the like, which are configured to be able to communicate with each other via a bus, and are well known to those skilled in the art. The CPU is a processor that controls the entire numerical control device 10. The CPU reads system programs and application programs stored in ROM via the bus and controls the entire numerical control device 10 in accordance with the system programs and application programs. As a result, as shown in FIG. 1, the control unit 200 is configured to implement the functions of a measurement means 210, a dynamic correction parameter calculation means 220, a command analysis means 230, a static correction means 240, a dynamic correction means 250, an interpolation means 260, an X-axis acceleration / deceleration control means 270, a Y-axis acceleration / deceleration control means 280, and a Z-axis acceleration / deceleration control means 290. The RAM stores various data such as temporary calculation data and display data. The CMOS memory is backed up by a battery (not shown) and is configured as a non-volatile memory that retains its stored state even when the numerical control device 10 is powered off.

[0023] For example, measuring means 210 causes a non-contact probe (not shown) included in machine tool 20 to measure on-machine the shape of a test workpiece (not shown) cut by machine tool 20 based on cutting commands of a machining program analyzed by command analysis means 230, which will be described later. Measuring means 210 acquires measurement data indicating the shape of the measured test workpiece (not shown) from machine tool 20. Furthermore, by measuring the shape on the machine, static errors occur equally during cutting and measurement, and as a result, static errors are canceled out in on-machine measurement, and only dynamic errors can be measured.

[0024] The dynamic correction parameter calculation means 220 calculates dynamic correction parameters for correcting dynamic errors based on a command shape indicated by a cutting command used to cut a test workpiece (not shown) and measurement data acquired by the measurement means 210. The dynamic correction parameter calculation means 220 stores the calculated dynamic correction parameters in dynamic correction parameter data 120 in the storage unit 100. The operation of the dynamic correction parameter calculation means 220 will be described later.

[0025] The command analysis means 230 sequentially reads out and analyzes blocks containing commands for movement along the X, Y, and Z axes from the machining program, and generates cutting commands containing command coordinate values ​​for movement along each axis based on the analysis results.

[0026] The static correction means 240 reads out the static errors from the static error data 110, and corrects the command coordinate values ​​of the cutting command generated by the command analysis means 230 based on the read out static errors.

[0027] The dynamic correction means 250 reads out the dynamic correction parameters calculated by the dynamic correction parameter calculation means 220 from the dynamic correction parameter data 120, and corrects the dynamic error for the command coordinate values ​​of the cutting command based on the read dynamic correction parameters.

[0028] The interpolation means 260 generates interpolated data by performing interpolation calculations on points on the command path at an interpolation period based on a movement command issued by the cutting command output from the dynamic correction means 250 .

[0029] The X-axis acceleration / deceleration control means 270 performs acceleration / deceleration processing based on the interpolation data output from the interpolation means 260, calculates the X-axis machining speed for each interpolation period, and outputs pulses corresponding to the calculated machining speed to the X-axis servo motor 31 of the machine tool 20.

[0030] The Y-axis acceleration / deceleration control means 280 performs acceleration / deceleration processing based on the interpolation data output from the interpolation means 260, calculates the Y-axis machining speed for each interpolation period, and outputs pulses corresponding to the calculated machining speed to the Y-axis servo motor 32 of the machine tool 20.

[0031] The Z-axis acceleration / deceleration control means 290 performs acceleration / deceleration processing based on the interpolation data output from the interpolation means 260, calculates the Z-axis machining speed for each interpolation period, and outputs pulses corresponding to the calculated machining speed to the Z-axis servo motor 33 of the machine tool 20.

[0032] Next, a description will be given of the calculation of the dynamic compensation parameters by the dynamic compensation parameter calculation means 220. Note that the dynamic errors in the machine tool 20 include squareness errors and errors due to the deflection of the tool 25. 3A is a diagram showing an example of a squareness error, and FIG. 3B is a diagram showing an example of an error due to deflection of the tool 25. As shown in FIG. 3A, when the rigidity between axes is low in an ultra-precision machining center or the like, squareness errors occur at the joints between table 21 and columns 22(1), 22(2), the joints between columns 22(1), 22(2) and column 23, and the joint between column 23 and spindle head 24, for example. On the other hand, as shown in FIG. 3B, an error due to tool deflection occurs in tool 25 attached to spindle head 24 when, for example, machine tool 20 has high rigidity but the cutting point load is large. Below, the calculation of the dynamic compensation parameters for squareness error and the calculation of the dynamic compensation parameters for deflection of the tool 25 will be described.

[0033] <Calculation of dynamic correction parameters for squareness error> As shown in Fig. 4, in order to calculate the dynamic compensation parameters for squareness error, the numerical control device 10 causes the machine tool 20 to cut a hole of radius R0 in a test workpiece 50 fixed to a jig 40 on the XY plane with the height in the Z-axis direction kept constant. Note that the cutting of the test workpiece 50 is performed under machining conditions, such as the same tool 25 and workpiece material as those used in cutting an actual product workpiece. In this way, the calculated dynamic compensation parameters can be applied when cutting an actual product workpiece. Then, the numerical control device 10 causes the machine tool 20 to measure the cut hole on-machine using a contact probe (not shown). The measuring means 210 of the numerical control device 10 acquires measurement data indicating the shape of the test workpiece 50 measured on-machine from the machine tool 20. In this way, by measuring the shape on the machine, static errors occur equally during cutting and measurement, and as a result, static errors are canceled out in on-machine measurement, and only dynamic errors can be measured.

[0034] The dynamic correction parameter calculation means 220 calculates the dynamic correction parameters based on the command shape indicated by the cutting command used to cut the test workpiece 50 and the acquired measurement data. Specifically, the dynamic correction parameter calculation means 220 calculates an ellipse ((x / R)) that best fits the measurement data shown by the solid line in FIG. x ) 2 +(y / R y ) 2 =1) is calculated, for example, by the least squares method, etc. The circle indicated by the dashed line in Fig. 5 indicates the command shape of a hole with a radius R0.

[0035] Note that the cutting point load during cutting of the test workpiece 50 is applied not only in the diameter direction of the circle but also in the circumferential direction of the circle depending on the cutting depth. As a result, as shown in Figure 5, the best-fit ellipse is tilted by an angle α. In other words, the movement command position R indicated by the cutting command n When R0(cosθ, sinθ) is used, the machining shape position R indicated by the measurement data a (R x cos(θ-α),R y sin(θ-α))). And the machining shape position R a The deviation amounts δ0 and δ when the angle θ is 0 degrees and 90 degrees 90 is expressed as in Equation 1. Here, the deviation amounts δ0 and δ 90 The directions of are parallel to the X-axis and Y-axis, respectively.

number

number

[0036] It should be noted that if the cutting point load during cutting of the test workpiece 50 is ideally only in the diameter direction of the circle, the best-fit ellipse will not be tilted and the angle α will be 0. If squareness error occurs due to the cutting point load, as shown in Figure 7, the dynamic compensation parameter W in Equation 2 zx , W zy is expressed as in equation 3. In other words, squareness error is an error that occurs when the perpendicularity of each axis is not met.

number

[0037] In this case, the amount of deviation δ is expressed as in equation 4.

number

number

[0038] Then, the dynamic correction parameter calculation means 220 calculates the dynamic correction parameter W using the formulas 1 and 2. zx , W zy The calculated dynamic correction parameter W zx , W zy is stored in the dynamic correction parameter data 120.

[0039] Thereafter, when cutting the workpiece of an actual product, the dynamic correction means 250 calculates the dynamic correction parameters W from the dynamic correction parameter data 120. zx , W zy The dynamic correction means 250 reads out the dynamic correction parameters W zx , W zy Based on this, it is possible to correct the dynamic error of the squareness error with respect to the command coordinate values ​​of the cutting command for the workpiece that will become the actual product.

[0040] <Calculation of dynamic compensation parameters for errors due to deflection of tool 25> As in the case of squareness error, numerical control device 10 calculates dynamic compensation parameters for errors due to deflection of tool 25 by having machine tool 20 cut a hole of radius R0 in test workpiece 50 fixed to jig 40 on the XY plane with its height in the Z-axis direction kept constant. Note that test workpiece 50 is cut under machining conditions, such as the same tool 25 and workpiece made of the same material, as used in cutting an actual product workpiece. In this way, the calculated dynamic compensation parameters can be applied when cutting an actual product workpiece. Then, the numerical control device 10 causes the machine tool 20 to measure the cut hole on-machine using a contact probe (not shown). The measuring means 210 of the numerical control device 10 acquires measurement data indicating the shape of the test workpiece 50 measured on-machine from the machine tool 20.

[0041] The dynamic correction parameter calculation means 220 calculates the dynamic correction parameters based on the command shape indicated by the cutting command used to cut the test workpiece 50 and the acquired measurement data. Specifically, since there is no anisotropy in the deflection of the tool 25, the dynamic correction parameter calculation means 220 calculates a circle (x 2 +y 2 =R t 2 ) is calculated by, for example, the least squares method. Note that the circle indicated by the dashed line in FIG. 8 indicates the command shape of a hole with a radius of R0, as in the case of FIG. However, as shown in FIG. 9, the direction of the cutting point load F is tilted at an angle β with respect to the normal to the test workpiece 50 due to the rotation of the tool 25 and the reaction from the test workpiece 50 to the rotation. For this reason, the commanded position and the actual cutting position are deviated from each other as shown in FIG. 8. Therefore, the dynamic correction parameter calculation means 220 calculates the tilt β of the direction of the cutting point load F using a known method (for example, Kazuo Taniguchi, "Dynamical Analysis of Metal Cutting Mechanism (Third Report)", Precision Machinery, Vol. 29, No. 3, 1963). This allows the coefficient (dynamic correction parameter) W of the deflection of the tool 25 that occurs due to the cutting point load to be calculated. t is expressed as in Equation 6.

number

number

[0042] The dynamic correction parameter calculation means 220 calculates the dynamic correction parameter W using Equation 6. t The calculated dynamic correction parameter W t is stored in the dynamic correction parameter data 120.

[0043] Thereafter, when cutting an actual product workpiece, the dynamic correction means 250 calculates the dynamic correction parameters W from the dynamic correction parameter data 120. t The dynamic correction means 250 reads out the dynamic correction parameters W tBased on this, the dynamic error due to the deflection of the tool 25 is corrected for the command coordinate values ​​of the cutting command for the workpiece that will be the actual product. As a result, as shown in FIG. 10, the tool 25 at the actual position indicated by the solid line can be moved to the position of the command coordinate values ​​indicated by the broken line.

[0044] As described above, the numerical control device 10 of the first embodiment measures the shape of the cut test workpiece 50 on-machine and acquires measurement data of the measured shape of the test workpiece 50. The numerical control device 10 calculates dynamic compensation parameters for compensating for dynamic errors based on the command shape of the cutting command and the acquired measurement data. The numerical control device 10 can compensate for dynamic errors with respect to command coordinate values ​​based on the calculated dynamic compensation parameters. This allows the numerical control device 10 to accurately correct dynamic errors without using a sensor that detects pressure due to tool deflection. Furthermore, by calculating the dynamic correction parameters, the numerical control device 10 does not need to check in advance the relationship between the cutting point load measured by a sensor or the like and the deflection of the tool. The first embodiment has been described above.

[0045] <Modification of the first embodiment> In the first embodiment described above, the numerical controller 10 corrects the dynamic error for the command coordinate values ​​of the cutting command generated by analyzing the machining program, but the present invention is not limited to this. For example, the numerical controller 10 may add correction pulses for correcting the dynamic error to the pulses output to the X-axis servo motor 31, the Y-axis servo motor 32, and the Z-axis servo motor 33 of the machine tool 20.

[0046] FIG. 11 is a diagram illustrating an example of a numerical control device 10 according to the first embodiment. 11, the static correction means 240-1 and the dynamic correction means 250-1 are arranged after the X-axis acceleration / deceleration control means 270, the Y-axis acceleration / deceleration control means 280, and the Z-axis acceleration / deceleration control means 290. The static correction means 240-1 and the dynamic correction means 250-1 correct static errors and dynamic errors by adding correction pulses for correcting static errors and correction pulses for correcting dynamic errors to pulses output from the X-axis acceleration / deceleration control means 270, the Y-axis acceleration / deceleration control means 280, and the Z-axis acceleration / deceleration control means 290. The static correction means 240-1 and the dynamic correction means 250-1 perform the same operations as the static correction means 240 and the dynamic correction means 250 in FIG. 1, except that they add correction pulses for static errors and correction pulses for dynamic errors.

[0047] Furthermore, the numerical control device 10 may incorporate the amount of dynamic correction into the tool diameter of the tool 25. FIG. 12 is a diagram illustrating an example of the numerical control device 10 according to the first embodiment. 12 performs dynamic correction for errors due to the deflection of the tool 25. In this case, the tool radius dynamic correction means 250-2 uses the dynamic correction parameter W calculated by Equation 6. t The correction amount calculated using the formula (8) is calculated based on the tool diameter r of the tool 25. t The tool diameter compensation amount r t ' may be calculated.

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[0048] Second Embodiment Next, a second embodiment will be described. In the first embodiment, if there is a difference in the magnitude of the load when machining the test workpiece 50 and when machining an actual product workpiece, that difference is not taken into account. In this case, for example, it is possible to automatically change the cutting conditions using a known method such as JP 2016-137557 A so that the difference in the magnitude of the cutting load is within a certain range (a range in which the numerical control device 10 functions normally). However, changing the cutting conditions is unavoidable. Therefore, in the second embodiment, in addition to the functions of the first embodiment, the numerical control device 10 interpolates a dynamic compensation parameter for an arbitrary cutting load using multiple dynamic compensation parameters calculated by cutting a test workpiece with each of multiple different cutting loads, and corrects the command coordinate value of the cutting command based on the interpolated dynamic compensation parameter for the arbitrary cutting load.

[0049] As a result, the numerical control device 10 of the second embodiment can appropriately correct dynamic errors even when the magnitude of the cutting point load when machining a test workpiece differs from the magnitude of the cutting point load when machining an actual product workpiece. The second embodiment will be described below.

[0050] 14 is a functional block diagram showing an example of a functional configuration of a numerical control device according to a second embodiment that is added to the numerical control device 10 of the first embodiment. Elements having the same functions as elements of the numerical control device 10 of FIG. 1 are given the same reference numerals, and detailed description thereof will be omitted. Since there is a strong correlation between the cutting load and the cutting volume per unit time, the following description will be given using the cutting volume V per unit time as a variable instead of the cutting load.

[0051] 14, the control unit 200 further includes a cutting load calculation means 300 and a dynamic correction parameter interpolation means 310. These functional units are realized by the control unit 200 executing a system program and an application program stored in the ROM (not shown) of the control unit 200.

[0052] The measuring means 210 measures, for example, a plurality of different cutting loads, i.e., a plurality of cutting volumes V1 to V2, which are measured by the machine tool 20 based on the cutting commands of the machining program analyzed by the command analyzing means 230. N The shape of each of the test workpieces 50 cut by each of the methods is measured on the machine using a non-contact probe (not shown) of the machine tool 20. N is an integer equal to or greater than 2. The measuring means 210 acquires measurement data of the shape of each of the measured test workpieces 50 from the machine tool 20.

[0053] In the case of squareness error, the dynamic correction parameter calculation means 220 calculates a plurality of cutting volumes V1 to V N Based on the command shape of the cutting command when the test workpiece 50 is cut by each of the cutting commands and the measurement data acquired by the measuring means 210, the dynamic correction parameters {W zx (V i ) | 1 ≦ i ≦ N, N is an integer greater than or equal to 2}, {W zy (V i )|1≦i≦N}. In addition, in the case of an error due to the deflection of the tool 25, the dynamic correction parameter calculation means 220 calculates a plurality of cutting volumes V1 to V N Based on the command shape of the cutting command when the test workpiece 50 is cut by each of the cutting commands and the measurement data acquired by the measuring means 210, the dynamic correction parameter {W t (V i )|1≦i≦N}. Then, the dynamic correction parameter calculation means 220 calculates the dynamic correction parameters {W zx (V i )|1≦i≦N}, {W zy (V i ) |1≦i≦N}, and the dynamic compensation parameter {W t (V i )|1≦i≦N} for cutting volumes V1 to V N are stored in the dynamic correction parameter data 120 in association with each of the above.

[0054] The cutting load calculation means 300 calculates the cutting volume V per unit time based on the machining conditions of the machining program analyzed by the command analysis means 230. Note that a known method can be used to calculate the cutting volume V from the machining conditions, and therefore a description thereof will be omitted.

[0055] The dynamic correction parameter interpolation means 310 extracts a plurality of dynamic correction parameters {W zx (V i )|1≦i≦N}, {W zy (V i ) |1≦i≦N} (or multiple dynamic correction parameters {W t (V i )|1≦i≦N}). The dynamic correction parameter interpolation means 310 reads out the plurality of read dynamic correction parameters {W zx (V i )|1≦i≦N}, {W zy (V i ) |1≦i≦N} (or multiple dynamic correction parameters {W t (V i )|1≦i≦N}) to calculate the dynamic correction parameter W in the cutting volume V calculated by the cutting load calculation means 300. zx (V), W zy (V) (or dynamic correction parameter W t (V)) is interpolated. The interpolation of the dynamic compensation parameters for squareness error and the interpolation of the dynamic compensation parameters for the deflection of the tool 25 will be described below.

[0056] <Interpolation of dynamic compensation parameters for squareness error> 15A and 15B are diagrams illustrating an example of the interpolation process of the dynamic correction parameter interpolation means 310. Note that FIG. 15A shows the dynamic correction parameter W zx (V), and Fig. 15B shows the dynamic correction parameter W zy 15A and 15B show the case where N=2, but the same applies when N is 3 or more.

[0057] The dynamic correction parameter interpolation means 310 interpolates the dynamic correction parameter W zx (V1), W zx (V2) is linearly interpolated to obtain the dynamic correction parameter W zx 15B, the dynamic correction parameter interpolation means 310 calculates the dynamic correction parameter W zy (V1), W zy (V2) is linearly interpolated to obtain the dynamic correction parameter W in the cutting volume V per unit time calculated by the cutting load calculation means 300. zy The dynamic correction parameter interpolation means 310 calculates the calculated dynamic correction parameter W zx (V), W zy (V) is output to the dynamic correction means 250. When N is 3 or more, the dynamic correction parameter interpolation means 310 may perform best fit using an M-th order function as shown in FIG. 16, or may obtain the parameters by machine learning (M is an integer of 2 or more).

[0058] Then, the dynamic correction means 250 calculates the dynamic correction parameter W calculated by the dynamic correction parameter interpolation means 310. zx (V), W zy Based on (V), the dynamic error of the squareness error is corrected for the command coordinate value of the cutting command for the workpiece that will be the actual product.

[0059] <Interpolation of dynamic compensation parameters for errors due to tool 25 deflection> The dynamic correction parameter interpolation means 310, as in the case of squareness error, calculates the dynamic correction parameters W t (V1), W t (V2) is linearly interpolated to obtain the dynamic correction parameter W t The dynamic correction parameter interpolation means 310 calculates the calculated dynamic correction parameter W t (V) is output to the dynamic correction means 250. When N is 3 or more, the dynamic correction parameter interpolation means 310 may perform best fit using an M-th order function, or may obtain the parameters by machine learning (M is an integer of 2 or more).

[0060] Then, the dynamic correction means 250 calculates the dynamic correction parameter W calculated by the dynamic correction parameter interpolation means 310. t Based on (V), the dynamic error due to the deflection of the tool 25 is corrected for the command coordinate values ​​of the cutting command for the workpiece that will be the actual product.

[0061] As described above, the numerical control device 10 of the second embodiment acquires measurement data of the shape of a test workpiece cut with each of a plurality of mutually different cutting volumes (cutting loads), and calculates dynamic correction parameters for each cutting volume based on the command shape and measurement data for each of the plurality of cutting volumes. The numerical control device 10 uses the calculated dynamic correction parameters for each cutting volume to interpolate dynamic correction parameters for an arbitrary cutting volume, and corrects command coordinate values ​​of a cutting command based on the interpolated dynamic correction parameters for the arbitrary cutting volume. This allows the numerical control device 10 to accurately correct dynamic errors without using a sensor that detects pressure due to tool deflection. Furthermore, the numerical control device 10 can appropriately correct dynamic errors even when the magnitude of the cutting load during machining of a test workpiece differs from the magnitude of the cutting load during machining of an actual product workpiece. The second embodiment has been described above.

[0062] <Modification of the second embodiment> In the second embodiment described above, the numerical controller 10 corrects dynamic errors in command coordinate values ​​of cutting commands generated by analyzing a machining program by adding the configuration of Fig. 14 to the numerical controller 10 of Fig. 1, but the present invention is not limited to this. For example, the numerical controller 10 may add correction pulses for correcting dynamic errors to pulses output to the X-axis servo motor 31, the Y-axis servo motor 32, and the Z-axis servo motor 33 of the machine tool 20 by adding the configuration of Fig. 14 to the numerical controller 10 of Fig. 11. Alternatively, the numerical controller 10 may incorporate the amount of dynamic compensation into the tool diameter of the tool 25 to compensate for the dynamic error by adding the configuration of FIG. 14 to the numerical controller 10 of FIG.

[0063] Third Embodiment Next, a third embodiment will be described. In the third embodiment, in addition to the functions of the first embodiment, the numerical control device 10 acquires the load current during cutting of a test workpiece, calculates a relation parameter indicating the relationship between the load current of each axis and the cutting point load based on the acquired load current, the deviation amount between the command shape and the measurement data, and the dynamic correction parameter, and calculates the cutting point load based on the relation parameter and the load current.

[0064] As a result, the numerical control device 10 of the third embodiment can estimate the cutting point load without modifying the hardware and without requiring additional hardware. The third embodiment will be described below.

[0065] 17 is a functional block diagram showing an example of a functional configuration of a numerical control device according to a third embodiment that is added to the numerical control device 10 of the first embodiment. Elements having the same functions as elements of the numerical control device 10 of FIG. 1 are given the same reference numerals, and detailed description thereof will be omitted.

[0066] 17, the control unit 200 further includes a related parameter calculation means 320 and a cutting point load calculation means 330. These functional units are realized by the control unit 200 executing a system program and an application program stored in the ROM (not shown) of the control unit 200.

[0067] The relational parameter calculation means 320 acquires load currents from the X-axis servo motor 31, the Y-axis servo motor 32, and the Z-axis servo motor 33 when cutting the test workpiece 50. The relational parameter calculation means 320 calculates relational parameters that indicate the relationship between the load currents and the cutting point loads at least on the X-axis and Y-axis based on the acquired load currents, the deviation δ between the command shape and the measurement data, and the dynamic correction parameters. Specifically, in order to calculate the relationship parameters indicating the relationship between the load currents in the X-axis and Y-axis and the cutting point load, the relationship parameter calculation means 320 causes the tool 25 attached to the spindle head 24 to make a circular movement clockwise on the XY plane at a constant speed without performing cutting, as shown in FIG. 18A. Since the tool 25 does not move in the Z-axis direction, the relationship parameter calculation means 320 obtains the load currents of the X-axis servo motor 31 and the Y-axis servo motor 32 when the tool 25 is making a circular movement. In this case, the load current I1(θ) is calculated as follows: (I 1x (θ),I 1y (θ)), where θ indicates the phase of the circular motion.

[0068] Similarly, as shown in FIG. 18B, the related parameter calculation means 320 does not perform cutting with the tool 25 attached to the spindle head 24, but rather causes it to circularly move counterclockwise on the XY plane at the same constant speed as in the clockwise direction. Since the tool 25 does not move in the Z-axis direction, the related parameter calculation means 320 obtains the load currents of the X-axis servo motor 31 and the Y-axis servo motor 32 when the tool 25 is circularly moving. In this case, the load current I2(θ) is calculated as follows: (I 2x (θ),I 2y (θ)). Here, the acceleration of load current I1(θ) and load current I2(θ) has the same direction in the normal direction, whereas the velocity of load current I1(θ) and load current I2(θ) has opposite directions in the tangential direction. As a result, the effect of velocity on I1(θ) + I2(θ) is cancelled out, leaving only the effect of acceleration. On the other hand, the effect of acceleration on I1(θ) - I2(θ) is cancelled out, leaving only the effect of velocity.

[0069] Therefore, the relational parameter calculation means 320 calculates the ellipse ((x / R ax ) 2 +(y / R ay ) 2 = 1) is calculated by, for example, the least squares method. The relation parameter calculation means 320 also calculates an ellipse ((x / R vx )2 +(y / R vy ) 2 =1) is calculated using, for example, the least squares method. As a result, I1(θ)+I2(θ) and I1(θ)−I2(θ) are expressed as in Equation 10.

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[0070] On the other hand, the proportionality coefficient K between the acceleration and torque on the X axis x , the proportionality coefficient K of the Y-axis acceleration and torque y , the proportionality coefficient L of the X-axis speed and torque x , Y-axis velocity and torque proportionality coefficient L y In this case, the load currents I1(θ) and I2(θ) are expressed as in equation 11. Note that a represents acceleration and v represents velocity.

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[0071] This gives the proportionality coefficient (relationship parameter between acceleration and load current) K x , K. y , and the proportional coefficient of the X-axis and Y-axis speed and torque (parameter relating the speed and load current) L x , L y is the value R of Eq. ax , R ay , R vx , R vy , a and v are used to express it as in Equation 13.

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[0072] In other words, the relational parameter calculation means 320 calculates the relational parameter K between the acceleration and the load current from the load currents I1(θ) and I2(θ), equations 10 and 13. x , K. y , and the relationship between speed and load current parameter L x , L y Then, the relation parameter calculation means 320 calculates the relation parameter K x , K. y , and the relationship between speed and load current parameter L x , L y The relation parameter calculation means 320 outputs the relation parameter K x , K. y , and the relationship between speed and load current parameter L x , L y may be stored in the storage unit 100.

[0073] Next, the numerical control device 10 calculates the dynamic correction parameter W for the squareness error in the same manner as in the first embodiment. zx , W zy , or a dynamic compensation parameter W for errors due to the deflection of the tool 25 t In order to calculate this, machine tool 20 is made to cut a hole of radius R0 in test workpiece 50 fixed to jig 40 on the XY plane with the height in the Z-axis direction kept constant. Then, the numerical control device 10 causes the machine tool 20 to measure the cut hole on-machine using a contact probe (not shown). The measuring means 210 of the numerical control device 10 acquires measurement data indicating the shape of the test workpiece 50 measured on-machine from the machine tool 20. As in the first embodiment, the dynamic correction parameter calculation means 220 calculates the dynamic correction parameter W for the squareness error based on the command shape indicated by the cutting command used to cut the test workpiece 50 and the acquired measurement data. zx , W zy , or a dynamic compensation parameter W for errors due to the deflection of the tool 25 t Calculate.

[0074] Furthermore, the relation parameter calculation means 320 calculates the load current I from the X-axis servo motor 31 and the Y-axis servo motor 32 during cutting of the test workpiece 50. f (X), I f The relation parameter calculation means 320 calculates the load current I (Y) during cutting. f (X), I f Using (Y), the proportional coefficient J (the parameter relating the load current and the cutting point load) between the X-axis load current and the cutting point load F is calculated. x , and the proportionality coefficient J between the Y-axis load current and the cutting point load F (the parameter for the relationship between the load current and the cutting point load) y Calculate. Below, the calculation of the relationship parameter between the load current and the cutting point load in the case of squareness error, and the calculation of the relationship parameter between the load current and the cutting point load in the case of deflection of the tool 25 will be described.

[0075] <Calculation of the parameter relating to the load current and cutting point load in squareness error> The relation parameter calculation means 320 calculates the squareness error caused by cutting the test workpiece 50 based on the acquired load current I f (=(I f (X), I f (Y)) to find the best-fit ellipse ((x / I fx ) 2 +(y / I fy ) 2 = 1) is calculated using, for example, the least squares method. fx is the radius of the ellipse in the X-axis direction. fy is the y-radius of the ellipse. Here, based on Equation 5, the amount of deviation δ (= (R0 - R x ,R0-R y )) is the machining height (coordinate value) z, the dynamic compensation parameter W for squareness error zx , W zy , and cutting point load F, it can be expressed as in Equation 14.

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[0076] The relation parameter calculation means 320 calculates the relation parameter I by using the equation (15) which is modified from the equation (14). fx , I fy and the dynamic correction parameter W read out from the dynamic correction parameter data 120. zx , W zy and R0 and R calculated by the dynamic correction parameter calculation means 220. x , R y Using this, the relationship between the load current and the cutting point load parameter J x , J y can be calculated.

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[0077] The cutting point load calculation means 330 calculates the relational parameter K between the acceleration and the load current calculated by the relational parameter calculation means 320 when cutting an actual product workpiece. x , K. y , and the relationship between speed and load current parameter L x , L y The load current I during cutting of the actual product workpiece obtained from the X-axis servo motor 31, the Y-axis servo motor 32, and the Z-axis servo motor 33 and equation (16) are used to calculate the load current I due to cutting. f Calculate.

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[0078] The dynamic correction means 250 reads out the dynamic correction parameter W from the dynamic correction parameter data 120. zx , W zy The deviation amount δ is calculated from the cutting point load F calculated by the cutting point load calculation means 330 and equation 5. The dynamic correction means 250 corrects the dynamic error of the squareness error with respect to the command coordinate values ​​of the cutting command for the actual product workpiece based on the calculated deviation amount δ.

[0079] <Calculation of the relationship parameter between load current and cutting point load when tool 25 is deflected> Although there is no anisotropy in the deflection of the tool 25, the magnitude of the load current required to generate the same cutting point load differs depending on the inertia of the shaft and the motor characteristics. Therefore, to generate a cutting point load, the radius is large in the axial direction that requires a large current (axial direction with large inertia), and the radius is small in the axial direction that requires a small current (axial direction with small inertia). Therefore, the relation parameter calculation means 320 calculates the load current I obtained when cutting the test workpiece 50. f (=(I f (X), I f The best-fit ellipse ((x / I ftx) 2 +(y / I fty ) 2 = 1) is calculated using, for example, the least squares method. ftx is the radius of the ellipse in the X-axis direction. fty is the y-radius of the ellipse. Here, based on Equation 7, the amount of deviation δ (= (R0 - R t ,R0-R t )) is the tool length L t , the dynamic correction parameter W t , and cutting point load F, it can be expressed as in Equation 18.

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[0080] The cutting point load calculation means 330 calculates the relational parameter K between the acceleration and the load current calculated by the relational parameter calculation means 320 when cutting an actual product workpiece. x , K. y , and the relationship between speed and load current parameter L x , L yThe load current I during cutting of the actual product workpiece obtained from the X-axis servo motor 31, the Y-axis servo motor 32, and the Z-axis servo motor 33 and equation (16) are used to calculate the load current I due to cutting. f Calculate. Then, the cutting point load calculation means 330 calculates the relation parameter J between the load current and the cutting point load calculated by the relation parameter calculation means 320. x , J y and the calculated load current I f and Equation 17 to calculate the cutting point load F.

[0081] The dynamic correction means 250 reads out the dynamic correction parameter W from the dynamic correction parameter data 120. t The deviation amount δ is calculated from the cutting point load F calculated by the cutting point load calculation means 330 and equation 7. The dynamic correction means 250 corrects the dynamic error due to the deflection of the tool 25 with respect to the command coordinate values ​​of the cutting command for the actual product workpiece based on the calculated deviation amount δ.

[0082] As described above, the numerical control device 10 of the third embodiment acquires the load current during cutting of the test workpiece 50, and calculates the relationship parameter J between the load current and the cutting point load based on the acquired load current, the deviation amount δ between the command shape and the measurement data, and the dynamic correction parameter. x , J y The numerical control device 10 calculates a parameter J x , J y and the load current I when cutting an actual product workpiece, the cutting point load F is calculated, and the dynamic error is corrected for the command coordinate value indicated by the cutting command based on the calculated cutting point load F and the dynamic correction parameters. This allows the numerical control device 10 to accurately correct dynamic errors without using a sensor. Furthermore, the numerical control device 10 can estimate the cutting point load without modifying the hardware and without requiring any additional hardware. The third embodiment has been described above.

[0083] <Modification of the third embodiment> In the above-described third embodiment, numerical controller 10 corrects dynamic errors in command coordinate values ​​of cutting commands generated by analyzing a machining program by adding the configuration of Fig. 17 to numerical controller 10 of Fig. 1, but the present invention is not limited to this. For example, numerical controller 10 may add correction pulses for correcting dynamic errors to pulses output to X-axis servo motor 31, Y-axis servo motor 32, and Z-axis servo motor 33 of machine tool 20 by adding the configuration of Fig. 17 to numerical controller 10 of Fig. 11. Alternatively, the numerical controller 10 may incorporate the amount of dynamic compensation into the tool diameter of the tool 25 to compensate for the dynamic error by adding the configuration of FIG. 17 to the numerical controller 10 of FIG.

[0084] Although the first to third embodiments have been described above, the numerical control device 10 is not limited to the above-described embodiments, and includes modifications, improvements, etc. within the scope of achieving the object.

[0085] <Modification> In the first to third embodiments described above, the machine tool 20 is a machine tool with three orthogonal axes, but it may also be a machine tool with five axes or the like.

[0086] Each function included in the numerical control device 10 according to the first to third embodiments can be realized by hardware, software, or a combination of these. Here, "realized by software" means that the function is realized by a computer reading and executing a program. Furthermore, each component included in the numerical control device 10 can be realized by hardware including electronic circuits, software, or a combination of these.

[0087] The program can be stored and supplied to a computer using various types of non-transitory computer-readable media. Non-transitory computer-readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic storage media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical storage media (e.g., magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / Ws, semiconductor memories (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, and RAMs. The program may also be supplied to a computer by various types of transitory computer-readable media. Examples of transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. The transitory computer-readable media can supply the program to a computer via a wired communication path such as an electric wire or optical fiber, or via a wireless communication path.

[0088] In addition, the steps of writing a program to be recorded on a recording medium include not only processes that are performed chronologically in accordance with the order, but also processes that are not necessarily performed chronologically but are performed in parallel or individually.

[0089] In other words, the numerical control device of the present disclosure can take various forms having the following configurations.

[0090] (1) The numerical control device 10 of the present disclosure is a numerical control device that causes the machine tool 20 to cut using command coordinate values ​​indicated by a cutting command received from a command analysis means 230, and is equipped with: a measurement means 210 that causes the machine tool 20 to measure the shape of the cut test work 50 on-machine and acquires measurement data indicating the measured shape of the test work 50; a dynamic correction parameter calculation means 220 that calculates dynamic correction parameters that correct dynamic errors caused by the forces and speeds acting on the machine tool 20 during cutting based on the command shape indicated by the cutting command and the measurement data acquired by the measurement means 210; and a dynamic correction means 250 that corrects the dynamic errors for the command coordinate values ​​based on the calculated dynamic correction parameters, and the dynamic correction parameter calculation means 220 acquires only the dynamic errors by comparing the command shape with the measurement data and calculates the dynamic correction parameters from the acquired dynamic errors. According to this numerical control device 10, dynamic errors can be corrected with high precision without using sensors.

[0091] (2) The command shape and the shape of the test workpiece 50 may be a circle. This makes it possible to easily calculate the dynamic correction parameters.

[0092] (3) The measuring means 210 acquires measurement data of a hole of radius R0 cut in the test workpiece 50 on the XY plane, and the dynamic correction parameter calculating means 220 best fits an ellipse to the shape of the test workpiece 50 shown in the measurement data, and calculates the radius R of each of the X and Y axes of the ellipse. x ,R y and obtain the dynamic correction parameter W in the XY plane. zx , W zy may be calculated using Equation 20.

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[0093] (4) The measurement means 210 acquires measurement data of a hole of radius R0 cut in the test workpiece 50 on the XY plane, and the dynamic correction parameter calculation means 220 best fits the shape of the test workpiece 50 indicated by the measurement data with a circle to obtain the radius R t and obtain a dynamic correction parameter W for the amount of deflection of the tool included in the machine tool 20 caused by the cutting load. t , and tool radius compensation amount r t ' may be calculated using Equation 21.

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[0094] (5) The apparatus may further include a dynamic correction parameter interpolation means 310, in which the measurement means 210 acquires measurement data of the shape of the test workpiece 50 cut with each of a plurality of different cutting loads, the dynamic correction parameter calculation means 220 calculates dynamic correction parameters based on the command shape and the measurement data for each of the plurality of cutting loads, the dynamic correction parameter interpolation means 310 uses the calculated plurality of dynamic correction parameters to interpolate dynamic correction parameters for any cutting load, and the dynamic correction means 250 may correct the command coordinate value of the cutting command based on the interpolated dynamic correction parameters for any cutting load. By doing so, even if the magnitude of the cutting load when machining the test workpiece 50 differs from the magnitude of the cutting load when machining the actual product workpiece, the dynamic error can be appropriately corrected.

[0095] (6) The apparatus may further include a relational parameter calculation means 320 that acquires the load current during cutting of the test workpiece, and calculates relational parameters that indicate the relationship between the load current and the cutting point load on at least the X-axis and Y-axis based on the acquired load current, the deviation amount between the command shape and the measurement data, and the dynamic correction parameters, and a cutting point load calculation means 330 that calculates the cutting point load based on the relational parameters and the load current. In this way, the cutting point load can be estimated without modifying the hardware and without the need for additional hardware.

[0096] (7) The load current may be calculated by subtracting the load current due to acceleration when tool 25 included in machine tool 20 is accelerated and the load current due to axial movement when tool 25 is moved axially from the load current of the servo motor included in machine tool 20. By doing so, the load current I f can be calculated.

[0097] (8) The load current due to acceleration and the load current due to axial movement may be calculated from the load current when the tool 25 moves without cutting. By doing so, the load current due to acceleration during idle machining and the load current due to axis movement can be calculated.

[0098] (9) The movement of the tool 25 that does not involve cutting may involve both a movement of the tool 25 in a circular clockwise direction and a movement of the tool 25 in a circular counterclockwise direction. By doing so, the load current due to acceleration and the load current due to axis movement can be calculated.

[0099] (10) The control method disclosed herein is a control method executed by a computer, in which the machine tool is caused to cut using command coordinate values ​​indicated by a cutting command received from a command analysis means 230, and includes a measurement step in which the machine tool 20 is caused to measure the shape of the cut test work 50 on-machine and acquire measurement data indicating the measured shape of the test work 50; a dynamic compensation parameter calculation step in which, based on the command shape indicated by the cutting command and the acquired measurement data, dynamic compensation parameters are calculated to compensate for dynamic errors caused by the forces and speeds acting on the machine tool 20 during cutting; and a dynamic compensation step in which, based on the calculated dynamic compensation parameters, the dynamic compensation parameter calculation step acquires only the dynamic error by comparing the command shape with the measurement data and calculates the dynamic compensation parameters from the acquired dynamic error. This control method can achieve the same effect as (1). [Explanation of symbols]

[0100] 10 Numerical Control Device 20 Machine tools 25 Tools 50 Test Work 100 Storage section 200 control section 210 Measurement means 220 Dynamic correction parameter calculation means 230 Command analysis means 250 Dynamic Correction Means 310 Dynamic correction parameter interpolation means 320 Related Parameter Calculation Method 330 Cutting point load calculation means

Claims

1. A numerical control device that causes a machine tool to cut using command coordinate values ​​indicated by a cutting command received from a command analysis means, a measuring means for causing the machine tool to measure the shape of the cut test workpiece on-machine and acquiring measurement data indicating the measured shape of the test workpiece; a dynamic correction parameter calculation means for calculating a dynamic correction parameter for correcting a dynamic error caused by a force and a speed acting on the machine tool during cutting, based on a command shape indicated by the cutting command and the measurement data acquired by the measurement means; and dynamic compensation means for compensating the dynamic error with respect to the command coordinate value based on the calculated dynamic compensation parameters by incorporating a compensation amount of dynamic compensation into at least a tool radius of a tool, the dynamic correction parameter calculation means obtains only the dynamic error from a comparison between the command shape and the measurement data, and calculates the dynamic correction parameter from the obtained dynamic error; the command shape and the shape of the test work are circles, The measuring means measures the radius R of the test workpiece cut in the XY plane. ０ obtaining the measurement data of the hole; The dynamic correction parameter calculation means The shape of the test workpiece indicated by the measurement data is best fitted to a circle, and the radius R of the circle is ｔ Get A dynamic correction parameter W for the amount of deflection of a tool included in the machine tool caused by cutting load ｔ and the tool radius compensation amount r t ′ are calculated by Equation 1. [Equation 1] where β is the angle between the workpiece normal direction and the cutting point load direction when cutting the test workpiece, and r ｔ indicates the tool diameter before correction, and L ｔ indicates the tool length, and β' indicates the angle between the workpiece normal direction and the cutting point load direction during actual cutting.

2. A control method executed by a computer to cause a machine tool to cut using command coordinate values ​​indicated by a cutting command received from a command analysis means, comprising: a measuring step of measuring the shape of the cut test workpiece on the machine tool and acquiring measurement data indicating the measured shape of the test workpiece; a dynamic compensation parameter calculation step of calculating, based on the command shape indicated by the cutting command and the acquired measurement data, a dynamic compensation parameter for compensating for a dynamic error caused by the force and speed acting on the machine tool during cutting; a dynamic compensation step of compensating the dynamic error with respect to the command coordinate value based on the calculated dynamic compensation parameters by incorporating a compensation amount of dynamic compensation into at least a tool radius of a tool, the dynamic correction parameter calculation step includes: obtaining only the dynamic error from a comparison between the command shape and the measurement data; and calculating the dynamic correction parameter from the obtained dynamic error; the command shape and the shape of the test work are circles, The measuring step is a step of measuring a radius R cut into the test workpiece in an XY plane. ０ obtaining the measurement data of the hole; The dynamic correction parameter calculation step includes: The shape of the test workpiece indicated by the measurement data is best fitted to a circle, and the radius R of the circle is ｔ Get A dynamic correction parameter W for the amount of deflection of a tool included in the machine tool caused by cutting load ｔ and the tool radius compensation amount r t ′ are calculated by the following equation (2). [Equation 2] where β is the angle between the workpiece normal direction and the cutting point load direction when cutting the test workpiece, and r ｔ indicates the tool diameter before correction, and L ｔ indicates the tool length, and β' indicates the angle between the workpiece normal direction and the cutting point load direction during actual cutting.

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