Numerical control device

Abstract

The goal is to create a path where the smoothing result is stable and within the tolerance threshold, even with two filter length parameters. The numerical control device comprises a program acquisition unit that acquires a machining program, a smoothing unit that obtains a smoothed path from the command path of the machining program, and a drive control unit that drives and controls the machine tool along the smoothed path. The smoothing unit obtains a smoothed path from the command path using a first smoothing characteristic parameter, calculates a difference vector between the command path and the smoothed path, obtains a difference vector from the difference vector using a second smoothing characteristic parameter, obtains a pullback path from the smoothed path and the smoothed difference vector, and sequentially changes one or both of the first and second smoothing characteristic parameters along the command path so that the difference between the command path and the pullback path is within a tolerance threshold.

Description

[Technical Field]

[0001] This disclosure relates to a numerical control device for calculating command paths to a machine tool. [Background technology]

[0002] Generally, NC programs (machining programs) created by CAM using minute line segments result in polyhedral or polygonal shapes. The numerical control system creates a smooth tool path from a sequence of minute points, thereby obtaining a smooth machined surface. For example, there is a known control device that generates a smoothed path by applying a low-pass filter to a commanded path instructed by a control program, calculates the amount by which the generated smoothed path curves inward relative to the commanded path, and outputs a path pulled back in the opposite direction to the inward curve of the smoothed path based on the calculated amount of inward curve. See, for example, Patent Document 1. Furthermore, there is a known numerical control device that generates a segmented point cloud based on the instructions of a machining program, generates a smoothed point cloud from the generated segmented point cloud, generates a reconstruction vector cloud from the segmented point cloud and the smoothed point cloud, generates a reconstruction point cloud from the generated reconstruction vector cloud, and performs machining with an interpolated shape based on the generated reconstruction point cloud. See, for example, Patent Document 2. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2023 / 058243 [Patent Document 2] Japanese Patent Publication No. 2001-117617 [Overview of the project] [Problems that the invention aims to solve]

[0004] The technology described in Patent Document 1 includes curvature calculation when calculating in the inward direction, but there is a problem that the curve (path) will not be stable if the result of the curvature calculation is not stable. On the other hand, the technology described in Patent Document 2 has the problem that although the curve is stable, there is no technique to keep the deviation from the original line segment (the group of divided points) within a tolerance (or tolerance threshold), and therefore the accuracy cannot be controlled. Furthermore, even if the technologies described in Patent Documents 1 and 2 are used in combination, the following problems arise. The tolerance check in the technology described in Patent Document 1 is a method that repeats calculations until the result is within the tolerance threshold. In the technology described in Patent Document 1, there is only one smoothing (filter), so it was sufficient to perform a convergence calculation to bring the result within the tolerance threshold by using the property that the deviation amount monotonically increases with respect to the filter length. However, in the method of the technology described in Patent Document 2, there are two smoothing processes and two filter length parameters, so the convergence calculation involves two variables, resulting in multiple solutions and making it difficult to determine the two filter lengths.

[0005] Therefore, even with two filter length parameters, it is desirable to create a path where the smoothing result is stable and within the tolerance threshold. [Means for solving the problem]

[0006] One embodiment of the numerical control device of the present disclosure is a numerical control device for driving and controlling a machine tool based on a machining program, comprising: a program acquisition unit for acquiring the machining program; a smoothing unit for obtaining a tool path after smoothing by applying smoothing to a command path commanded by the acquired machining program; and a drive control unit for driving and controlling the machine tool according to the tool path after smoothing, wherein the smoothing unit comprises: a first smoothing application unit for applying smoothing to the command path using a first smoothing characteristic parameter to create a path after smoothing; a difference vector calculation unit for calculating a difference vector between the command path and the path after smoothing; and a second smoothing characteristic parameter for the difference vector The drive control unit includes a second smoothing application unit that applies smoothing using a t and creates a difference vector after smoothing, a pull-back unit that obtains a pull-back path by pulling back the difference vector after smoothing from the smoothed path, and a smoothing characteristic parameter determination unit that sequentially changes either or both of the first smoothing characteristic parameter and the second smoothing characteristic parameter along the command path so that the difference between the command path and the pull-back path is within a predetermined tolerance threshold, and the drive control unit drives the machine tool according to the pull-back path calculated using the first smoothing characteristic parameter and the second smoothing characteristic parameter determined by the smoothing characteristic parameter determination unit. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows an example of a functional block configuration of a numerical control device according to one embodiment. [Figure 2] This diagram illustrates the smoothing process performed by the smoothing unit. [Figure 3] This is a flowchart explaining the decision-making process of a numerical control device. [Modes for carrying out the invention]

[0008] A numerical control device according to one embodiment will be described in detail below with reference to the figures. First, the outline of this embodiment will be described. In this embodiment, the numerical control device is a numerical control device that drives and controls a machine tool based on a machining program, and includes a smoothing unit that obtains a tool path after smoothing by applying smoothing to the command path commanded by the acquired machining program. The smoothing unit applies smoothing to the command path using a first smoothing characteristic parameter to create a path after smoothing, calculates a difference vector between the command path and the path after smoothing, applies smoothing to the difference vector using a second smoothing characteristic parameter to create a difference vector after smoothing. Then, the smoothing unit obtains a pullback path by pulling back the difference vector after smoothing from the path after smoothing, and sequentially changes either or both of the first smoothing characteristic parameter and the second smoothing characteristic parameter along the command path so that the difference between the command path and the pullback path is within a predetermined tolerance threshold. The numerical control device drives and controls the machine tool according to the pullback path calculated using the determined first smoothing characteristic parameter and the second smoothing characteristic parameter. As a result, according to this embodiment, even if there are two filter length parameters, it is possible to create a path in which the smoothing result is stable and within the tolerance threshold. The above is an overview of this embodiment.

[0009] Figure 1 shows an example of the functional block configuration of a numerical control device according to one embodiment. The numerical control device 10 is, for example, a numerical control device known to those skilled in the art, which generates commands by executing a machining program created by a CAD / CAM device (not shown) and controls a machine tool (not shown). As shown in Figure 1, the numerical control device 10 has a program acquisition unit 101, a smoothing unit 102, and a drive control unit 103. The smoothing unit 102 also has a first smoothing application unit 1021, a difference vector calculation unit 1022, a second smoothing application unit 1023, a pull-back unit 1024, and a smoothing characteristic parameter determination unit 1025.

[0010] Furthermore, the numerical control device 10 includes an arithmetic processing unit (not shown), such as a CPU (Central Processing Unit), to realize the operation of the functional blocks shown in Figure 1. In addition, the numerical control device 10 includes auxiliary storage devices (not shown), such as a ROM (Read Only Memory) or HDD (Hard Disk Drive), which store various control programs, and main memory devices (not shown), such as a RAM (Random Access Memory), for storing data temporarily required when the arithmetic processing unit executes a program.

[0011] In the numerical control unit 10, the arithmetic processing unit reads the OS and application software from the auxiliary storage device, and while expanding the read OS and application software into the main memory, performs arithmetic processing based on this OS and application software. Based on the results of this calculation, the numerical control unit 10 controls each piece of hardware. This realizes the processing shown by the functional blocks in Figure 1. In other words, each function of the numerical control unit 10 is realized through the cooperation of hardware and software.

[0012] The program acquisition unit 101 acquires a machining program created by, for example, a CAD / CAM device (not shown).

[0013] The smoothing unit 102 obtains a tool path after smoothing by performing smoothing on the commanded path commanded by the acquired machining program. Hereinafter, the smoothing process by the smoothing unit 102 will be described with reference to FIG. 2. In FIG. 2, the dashed line indicates the commanded path P(s), the solid line indicates the path Q(s, l1) obtained by smoothing the commanded path P(s) by the first smoothing application unit 1021 described later, and the thick line indicates the retracted path R(s, l1, l2) retracted more by the retraction unit 1024 described later. Note that the commanded path P(s) is a three-dimensional vector having coordinate values of the X-axis, Y-axis, and Z-axis as elements, and a point on the commanded path P(s) (that is, a vertex of a polygon) indicates a commanded position (command point). Also, s is a parameter of the parametric curve. Since the method of representing the commanded path by a parametric curve is a known technique, the description thereof will be omitted.

[0014] First, the first smoothing application unit 1021 of the smoothing unit 102 applies smoothing to the commanded path commanded by the machining program using the first smoothing characteristic parameter, and creates a path after the smoothing application. Specifically, for example, as the smoothing, the first smoothing application unit 1021 calculates the path Q(s, l1) after the smoothing application represented by Equation (1) by applying a low-pass filter F to the commanded path P(s). Q(s, l1)=F(l1)·P(s) ···(1) Here, l1 is a parameter indicating the filter length of the low-pass filter F. Also, here, "·" represents the action (filter application) by F(l1). Note that although the smoothing is performed by the low-pass filter F, interpolation by a parametric curve or fitting by a parametric curve may also be used. As shown in FIG. 2, the path Q(s, l1) after the smoothing application becomes a path that turns inward from the commanded path P(s).

[0015] The difference vector calculation unit 1022 calculates the difference vector V(s,l1) between the command path P(s) and the path Q(s,l1) after smoothing is applied, using equation (2). V(s,l1)=Q(s,l1)-P(s) ···(2)

[0016] The second smoothing application unit 1023 applies smoothing to the difference vector V(s,l1) using the second smoothing characteristic parameter l2 to create a difference vector (path difference) U(s,l1,l2) after smoothing, which is represented by equation (3). U(s,l1,l2)=F(l2)·V(s,l1)···(3) Here, the second smoothing characteristic parameter l2 represents the filter length of the low-pass filter F. Note that F(l1) and F(l2) are both low-pass filters, and as will be described later, the first smoothing characteristic parameter l1 and the second smoothing characteristic parameter l2 may have different filter lengths or the same filter length.

[0017] The pullback unit 1024 obtains a pullback path R(s,l1,l2) by pulling back the difference vector U(s,l1,l2) after smoothing applied in the direction of the command path P(s) from the path Q(s,l1) after smoothing applied, for example using equation (4). R(s,l1,l2)=Q(s,l1)+U(s,l1,l2) ...(4)

[0018] The smoothing characteristic parameter determination unit 1025 sequentially changes either or both of the first smoothing characteristic parameter l1 and the second smoothing characteristic parameter l2 along the command path P(s) so that the difference between the command path P(s) and the pullback path R(s,l1,l2) is within a predetermined tolerance threshold. Here, as shown in Figure 2, the pullback path R(s,l1,l2) is a smoothed path, so it differs from the original command path P(s). Therefore, the smoothing characteristic parameter determination unit 1025 determines the first smoothing characteristic parameter l1 and the second smoothing characteristic parameter l2 so that the pull-back path R(s,l1,l2) does not deviate too far from the original command path P(s), and so that the amount of deviation does not exceed a preset tolerance value (tolerance threshold). Here, the tolerance condition is expressed as shown in equation (5), where tol is a predetermined tolerance threshold and D(s,l1,l2) is the difference between the pullback path R(s,l1,l2) and the command path P(s).

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[0019] The operation of the smoothing characteristic parameter determination unit 1025 will be explained below by illustrating two cases: (a) when the first smoothing characteristic parameter l1 and the second smoothing characteristic parameter l2 have different filter lengths, and (b) when the first smoothing characteristic parameter l1 and the second smoothing characteristic parameter l2 have the same filter length.

[0020] (a) When the first smoothing characteristic parameter l1 and the second smoothing characteristic parameter l2 have different filter lengths. In this case, the first smoothing characteristic parameter l1 is set to a fixed value L, and the second smoothing characteristic parameter l2 is set to a·L. The smoothing characteristic parameter determination unit 1025 determines the first smoothing characteristic parameter l1 and the second smoothing characteristic parameter l2 by determining the value of coefficient a that results in the smoothest path while satisfying the tolerance conditions. The coefficient a is a value between 0 and 1. L is the maximum value of the smoothing characteristic parameter, and is determined, for example, by the average of the block lengths (length between command positions) in the machining program. As a result, equation (9) can be transformed into equation (10). R(s,l1,l2) = R'(s,L,a) = F(a·L)·P(s)+F(L)·P(s) -F(a·L)·F(L)·P(s) ...(10) Here, when coefficient a is 0, equation (10) becomes R'(s,L,0)=F(0)·P(s)+F(L)·P(s)-F(0)·F(L)·P(s). And since the low-pass filter F(0) with a filter length of 0 is equivalent to doing nothing, R'(s,L,0)=P(s). That is, when coefficient a is 0, the pullback path R(s,l1,l2) (=R'(s,L,a)) and the command path P(s) coincide, and the deviation amount D becomes 0. Therefore, the smoothing characteristic parameter determination unit 1025 fixes the first smoothing characteristic parameter l1 by changing the coefficient a based on equation (7) (or equation (8)) and equation (10), thereby determining the smoothest path R'(s,L,a) that is within the tolerance threshold tol. max ) obtain.

[0021] The first smoothing characteristic parameter l1 (=L) may be determined from the frequency of the high-frequency components to be removed as a low-pass filter F. Furthermore, if the purpose of smoothing is to smooth the command path P(s) of a machining program that is commanded in a polygonal manner, the first smoothing characteristic parameter l1 may be set to be approximately equal to or greater than the block length.

[0022] (b) When the first smoothing characteristic parameter l1 and the second smoothing characteristic parameter l2 have the same filter length. In this case, the first smoothing characteristic parameter l1 and the second smoothing characteristic parameter l2 are set to the same value a·L. The smoothing characteristic parameter determination unit 1025 determines the first smoothing characteristic parameter l1 and the second smoothing characteristic parameter l2 by changing both the first smoothing characteristic parameter l1 and the second smoothing characteristic parameter l2 to determine the value of coefficient a that results in the smoothest path while satisfying the tolerance condition. Equation (9) can be transformed into equation (11). R(s,l1,l2) = R'(s,L,a) = F(a·L)·P(s)+F(a·L)·P(s) -F(a·L)·F(a·L)·P(s) ...(11) Here, when coefficient a is 0, equation (11) becomes R'(s,L,0)=F(0)·P(s)+F(0)·P(s)-F(0)·F(0)·P(s). And since the low-pass filter F(0) with a filter length of 0 is equivalent to doing nothing, R'(s,L,0)=P(s). That is, when coefficient a is 0, the pullback path R(s,l1,l2) (=R'(s,L,a)) and the command path P(s) coincide, and the deviation amount D becomes 0. Utilizing this property, the smoothing characteristic parameter determination unit 1025 determines the value of coefficient a using equation (12).

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[0023] The drive control unit 103 calculates the pullback path R'(s,L,a) using the first smoothing characteristic parameter l1 and the second smoothing characteristic parameter l2 determined by the smoothing characteristic parameter determination unit 1025. max The machine tool is driven and controlled according to the following.

[0024] <Decision processing of numerical control device 10> Next, the decision-making process of the numerical control device 10 will be explained with reference to Figure 3. Figure 3 is a flowchart illustrating the decision-making process of the numerical control device 10. This flowchart is executed repeatedly each time a machining program is acquired. The first smoothing characteristic parameter l1 and the second smoothing characteristic parameter l2 are pre-set to L for one and a·L for the other, or to a·L for both.

[0025] In step S11, the program acquisition unit 101 acquires a machining program created by a CAD / CAM device (not shown).

[0026] In step S12, the first smoothing application unit 1021 applies smoothing to the command path P(s) commanded by the machining program acquired in step S11 using the first smoothing characteristic parameter l1, and calculates the path Q(s,l1) after smoothing application.

[0027] In step S13, the difference vector calculation unit 1022 calculates the difference vector V(s,l1) between the command path P(s) and the path Q(s,l1) after smoothing is applied, using equation (2).

[0028] In step S14, the second smoothing application unit 1023 applies smoothing to the difference vector V(s,l1) using the second smoothing characteristic parameter l2, using equation (3), and calculates the difference vector U(s,l1,l2) after smoothing application.

[0029] In step S15, the pullback unit 1024 uses equation (4) to calculate the pullback path R(s,l1,l2) obtained by pulling back the difference vector U(s,l1,l2) after smoothing in the direction of the command path P(s) from the path Q(s,l1) after smoothing.

[0030] In step S16, the smoothing characteristic parameter determination unit 1025 sets the coefficient a to a predetermined value (for example, "1") and calculates the deviation amount D(s,l1,l2) using equation (7) (or equation (8)).

[0031] In step S17, the smoothing characteristic parameter determination unit 1025 determines whether the deviation amount D(s,l1,l2) is within the tolerance threshold tol. If the deviation amount D(s,l1,l2) is within the tolerance threshold tol, the process proceeds to step S19. On the other hand, if the deviation amount D(s,l1,l2) is greater than the tolerance threshold tol, the process proceeds to step S18.

[0032] In step S18, the smoothing characteristic parameter determination unit 1025 changes the value of coefficient a from "1" to "0.9" or "0.5" by, for example, iteration, so that the deviation amount D(s,l1,l2) is within the tolerance threshold tol. Then the process returns to step S16.

[0033] In step S19, the smoothing characteristic parameter determination unit 1025 determines the first smoothing characteristic parameter l1 and the second smoothing characteristic parameter l2 using the coefficient a which is within the tolerance threshold tol.

[0034] As described above, the numerical control device 10 according to one embodiment can create a path in which the smoothing result is stable and within the tolerance threshold, even if there are two filter length parameters l1 and l2, by not using curvature calculation when calculating in the inward direction. Furthermore, the numerical control device 10 does not directly clamp the correction amount, but adjusts the filter characteristics of the low-pass filter F, fixing one of the two filter lengths l1 and l2, or making both of the two filter lengths l1 and l2 the same, thereby making it difficult for the high-frequency rejection effect to decrease. This allows the smoothing effect to be adjusted so that it remains within the tolerance threshold tol while preserving the high-frequency rejection effect without compromising smoothness.

[0035] <Example 1> In one embodiment, the first smoothing characteristic parameter l1, the second smoothing characteristic parameter l2, the maximum value L of the smoothing characteristic parameter, the coefficient a, and the coefficient a max This is not limited to the assumption that it does not depend on the position on the parametric curve. For example, the first smoothing characteristic parameter l1, the second smoothing characteristic parameter l2, the maximum value L of the smoothing characteristic parameter, coefficient a, coefficient a max This can also be a function of the parameter s of the parametric curve. That is, the first smoothing characteristic parameter l1(s), the second smoothing characteristic parameter l2(s), the maximum value L(s) of the smoothing characteristic parameter, the coefficient a(s), the coefficient a maxIt may be (s). This means that the smoothing characteristic parameter changes depending on the location of the path. In particular, a max may be obtained using Equation (13). [Number] Furthermore, as in Equation (14), it may be used after applying the low-pass filter F, or values to which other smoothing has been applied may be used. a’ max (s) = F(l a )·a max (s) ···(14) Here, l a is the smoothing characteristic parameter (filter length), and is the block length or the like, similar to the first smoothing characteristic parameter l1 and the second smoothing characteristic parameter l2.

[0036] [Modification Example 2] In the above-described embodiment, when the smoothing characteristic parameter determination unit 1025 sets the first smoothing characteristic parameter l1 to the fixed value L and the second smoothing characteristic parameter l2 to the value a·L, the divergence amount D(s, l1, l2) of the difference between the command path P(s) and the feedback path R(s, l1, l2) determines the coefficient a such that it is within the tolerance threshold tol, but is not limited to this. For example, the smoothing characteristic parameter determination unit 1025 may set the second smoothing characteristic parameter l2 to the fixed value L and the first smoothing characteristic parameter l1 to the value a·L. Also, the smoothing characteristic parameter determination unit 1025 may determine the value of the first smoothing characteristic parameter l1 (or the second smoothing characteristic parameter l2) to be fixed based on the spatial frequency of the high-frequency component to be removed. Furthermore, the smoothing characteristic parameter determination unit 1025 may determine the spatial frequency of the high-frequency component to be removed based on the block length of the machining program.

[0037] In one embodiment, each function included in the numerical control device 10 can be implemented by hardware, software, or a combination thereof. Here, implementation by software means that it is implemented by a computer reading and executing a program.

[0038] Programs can be stored and supplied to a computer using various types of non-transitory computer-readable medium. Non-transitory computer-readable mediums include various types of tangible storage mediums. Examples of non-transitory computer-readable mediums 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, and semiconductor memory (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, RAMs). Programs may also be supplied to a computer using various types of transient computer-readable mediums. Examples of transient computer-readable mediums include electrical signals, optical signals, and electromagnetic waves. Transitory computer-readable mediums can be supplied to a computer via wired communication channels such as electric wires and optical fibers, or via wireless communication channels.

[0039] Furthermore, the step of executing the program recorded on the recording medium includes not only processes that are performed chronologically in that order, but also processes that are not necessarily performed chronologically, but are executed in parallel or individually. In addition, the step of writing the program may be performed using cloud computing.

[0040] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the spirit of this disclosure derived from the claims and their equivalents. Furthermore, these embodiments can be implemented in combination. For example, the order of operations and processes in the embodiments described above are shown as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above.

[0041] The following additional information is disclosed regarding the above embodiments and modifications. (Note 1) The numerical control device (10) is a numerical control device that drives and controls a machine tool based on a machining program, and comprises a program acquisition unit (101) that acquires a machining program, a smoothing unit (102) that obtains a tool path after smoothing by applying smoothing to a command path (P) commanded by the acquired machining program, and a drive control unit (103) that drives and controls the machine tool according to the tool path after smoothing, and the smoothing unit (102) comprises a first smoothing application unit (1021) that applies smoothing to the command path (P) using a first smoothing characteristic parameter (l1) to create a path (Q) after smoothing, a difference vector calculation unit (1022) that calculates a difference vector (V) between the command path (P) and the path (Q) after smoothing, and a second smoothing characteristic parameter (l2) that applies smoothing to the difference vector (V) The system includes a second smoothing application unit (1023) that applies smoothing and creates a difference vector (U) after smoothing, a pull-back unit (1024) that obtains a pull-back path (R) by pulling back the difference vector (U) after smoothing from the path (Q) after smoothing, and a smoothing characteristic parameter determination unit (1025) that sequentially changes either or both of the first smoothing characteristic parameter (l1) and the second smoothing characteristic parameter (l2) along the command path (P) so that the difference between the command path (P) and the pull-back path (R) is within a predetermined tolerance threshold (tol), and the drive control unit (103) drives and controls the machine tool according to the pull-back path (R) calculated using the first smoothing characteristic parameter (l1) and the second smoothing characteristic parameter (l2) determined by the smoothing characteristic parameter determination unit (1025). (Note 2) In the numerical control device (10) described in Appendix 1, the smoothing of the command path (P) by the first smoothing application unit (1021) and the smoothing of the difference vector (V) by the second smoothing application unit (1023) are at least one of the following: processing by a low-pass filter (F), interpolation by a parametric curve, or fitting by a parametric curve. (Note 3) In the numerical control device (10) described in Appendix 1, the smoothing characteristic parameter determination unit (1025) determines one of the first smoothing characteristic parameter (l1) and the second smoothing characteristic parameter (l2) to a fixed value, and the other to a value such that the difference between the command path (P) and the pullback path (R) is within a predetermined tolerance threshold (tol). (Note 4) In the numerical control device (10) described in Appendix 3, the smoothing characteristic parameter determination unit (1025) determines the value of the first smoothing characteristic parameter (l1) or the second smoothing characteristic parameter (l2) to be fixed based on the spatial frequency of the high-frequency component to be removed. (Note 5) In the numerical control device (10) of Appendix 4, the smoothing characteristic parameter determination unit (1025) determines the spatial frequency of the high-frequency component to be removed based on the block length of the processing program. (Note 6) In the numerical control device (10) described in Appendix 1, the smoothing characteristic parameter determination unit (1025) determines the first smoothing characteristic parameter (l1) and the second smoothing characteristic parameter (l2) to the same value such that the difference between the command path (P) and the pullback path (R) is within a predetermined tolerance threshold (tol). [Explanation of symbols]

[0042] 10 Numerical control device 101 Program Acquisition Section 102 Smoothing section 1021 First smoothing application section 1022 Difference Vector Calculation Unit 1023 Second smoothing application section 1024 Pull-back section 1025 Smoothing Specific Parameter Determination Unit 103 Drive control unit

Claims

1. A numerical control device that drives and controls a machine tool based on a machining program, A program acquisition unit that acquires the aforementioned processing program, A smoothing unit that obtains a tool path after smoothing by applying smoothing to the command path instructed by the acquired machining program, The machine tool is driven and controlled according to the tool path after smoothing, and the machine tool is driven and controlled accordingly. The smoothing portion is, A first smoothing application unit applies smoothing to the command path using a first smoothing characteristic parameter to create a path after smoothing has been applied, A difference vector calculation unit calculates the difference vector between the command path and the path after smoothing is applied, A second smoothing application unit applies smoothing to the difference vector using a second smoothing characteristic parameter to create a difference vector after smoothing, A pull-back unit obtains a pull-back path by pulling back the difference vector after smoothing from the path after smoothing, The system includes a smoothing characteristic parameter determination unit that sequentially modifies either or both of the first smoothing characteristic parameter and the second smoothing characteristic parameter along the command path so that the difference between the command path and the pullback path is within a predetermined tolerance threshold, The drive control unit drives the machine tool according to the pull-back path calculated using the first smoothing characteristic parameter and the second smoothing characteristic parameter determined by the smoothing characteristic parameter determination unit. Numerical control device.

2. The numerical control device according to claim 1, wherein the smoothing of the command path by the first smoothing application unit and the smoothing of the difference vector by the second smoothing application unit are at least one of processing by a low-pass filter, interpolation by a parametric curve, or fitting by a parametric curve.

3. The numerical control device according to claim 1, wherein the smoothing characteristic parameter determination unit determines one of the first smoothing characteristic parameter and the second smoothing characteristic parameter to a fixed value, and the other to a value such that the difference between the command path and the pull-back path is within a predetermined tolerance threshold.

4. The numerical control device according to claim 3, wherein the smoothing characteristic parameter determination unit determines the value of the first smoothing characteristic parameter or the second smoothing characteristic parameter to be fixed based on the spatial frequency of the high-frequency component to be removed.

5. The numerical control device according to claim 4, wherein the smoothing characteristic parameter determination unit determines the spatial frequency of the high-frequency component to be removed based on the block length of the processing program.

6. The numerical control device according to claim 1, wherein the smoothing characteristic parameter determination unit determines the first smoothing characteristic parameter and the second smoothing characteristic parameter to be the same value such that the difference between the command path and the pullback path is within a predetermined tolerance threshold.

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