Control device and control method

Abstract

According to the present invention, a control device for a wire electrical discharge machine that machines a workpiece by discharging electricity across the electrode gap between a wire electrode and the workpiece while moving the wire electrode relative to the workpiece along a machining path comprises a storage unit that stores boundary positions at which the workpiece has different sheet thicknesses, an electrode position detection unit that detects an electrode position for the wire electrode, and a machining control unit that, when the relative distance along the machining path between a boundary position and the electrode position is within a prescribed range, causes the wire electrical discharge machine to machine the workpiece using boundary machining conditions that are different from normal machining conditions that are used when the relative distance is outside the prescribed range.

Description

Control device and control method

[0001] The present disclosure relates to a control device and a control method.

[0002] Japanese Patent Application Laid-Open No. 2007-144567 discloses a wire cut electrical discharge machining method. In rough machining, the step position of the plate thickness is memorized. In finish machining, when the machining part reaches the area around the step position, the desired machining conditions are changed to the machining conditions suitable for the plate thickness.

[0003] During machining of the workpiece, streaks may occur on the machining surface of the workpiece at the boundary position where the plate thickness of the workpiece is different.

[0004] An object of the present disclosure is to solve the above-described problems.

[0005] A first aspect of the present disclosure is a control device for a wire electrical discharge machining machine that machines a workpiece by performing electrical discharge between a wire electrode and the workpiece while relatively moving the wire electrode along a machining path with respect to the workpiece, the control device including: a storage unit that stores a boundary position where the plate thickness of the workpiece is different; an electrode position detection unit that detects the electrode position of the wire electrode; and a machining control unit that causes the wire electrical discharge machining machine to machine the workpiece using boundary machining conditions different from normal machining conditions used when the relative distance between the boundary position and the electrode position on the machining path is outside a predetermined range, when the relative distance is within the predetermined range.

[0006] A second aspect of the present disclosure is a control method for a wire electrical discharge machining machine that machines a workpiece by performing electrical discharge between a wire electrode and the workpiece while relatively moving the wire electrode along a machining path with respect to the workpiece, the control method including: an electrode position detection step of detecting the electrode position of the wire electrode; and a machining control step of causing the wire electrical discharge machining machine to machine the workpiece using boundary machining conditions different from normal machining conditions used when the relative distance between the boundary position where the plate thickness of the workpiece is different, stored by a storage unit, and the electrode position on the machining path is outside a predetermined range, when the relative distance is within the predetermined range.

[0007] According to this disclosure, the occurrence of streaks on the processed surface of a workpiece can be reduced at boundary locations where the thickness of the workpiece differs.

[0008] Figure 1 shows a wire electrical discharge machining machine and its control device. Figure 2 is a block diagram illustrating the configuration of the control device. Figure 3 is a schematic diagram illustrating the machining of a workpiece with varying plate thickness. Figure 4 is a diagram illustrating the machining conditions for finishing, which can be used depending on the relative distance between the boundary position and the electrode position. Figure 5 is a diagram illustrating some of the parameters included in the normal machining conditions and boundary machining conditions in finishing. Figure 6 is a flowchart illustrating the processing procedure for controlling a wire electrical discharge machining machine during rough machining of a workpiece. Figure 7 is a flowchart illustrating the processing procedure for controlling a wire electrical discharge machining machine during finishing of a workpiece. Figure 8 is a diagram illustrating an example in which the parameters of the boundary machining conditions are determined by multiplying the parameters included in the normal machining conditions by a ratio.

[0009] Figure 1 shows a wire electrical discharge machining (EDM) machine 10 and its control device 20. The control device 20 shown in Figure 1 is housed in the same housing as the machining power supply 30. However, the control device 20 may be housed in a separate housing from the machining power supply 30. The machining power supply 30 generates a discharge by applying a voltage to the space G (see Figure 3) between the wire electrode 60 and the workpiece W (see Figure 3). The workpiece W is supported by a table 62.

[0010] The wire electrical discharge machining machine 10 performs electrical discharge between electrodes G while moving the wire electrode 60 relative to the workpiece W along the machining path Rt (see Figure 3). That is, a machining current flows between electrodes G at the electrode position P (see Figure 3) of the wire electrode 60 on the machining path Rt. As a result, the wire electrical discharge machining machine 10 can perform electrical discharge machining on the workpiece W.

[0011] The machining path Rt is predetermined by a set program. While electrical discharge machining is being performed, the control device 20 moves the wire electrode 60 relative to the workpiece W along the machining path Rt. The relative movement between the wire electrode 60 and the workpiece W is performed, for example, by moving the table 62.

[0012] The wire electrical discharge machining machine 10 has an upper wire guide 64 and a lower wire guide 66. The upper wire guide 64 includes an upper guide block 68, an upper die guide 70, and an upper nozzle (not shown). The lower wire guide 66 includes a lower guide block 72, a lower die guide 74, and a lower nozzle (not shown). The upper wire guide 64 supports the wire electrode 60 above the table 62 and the workpiece W. The lower wire guide 66 supports the wire electrode 60 below the table 62.

[0013] The wire electrode 60 is supplied from the wire bobbin 76 at a predetermined speed in the feeding direction. The wire electrode 60 is fed out via the roller 78, the upper wire guide 64, the workpiece W, and the lower wire guide 66. After passing through the lower wire guide 66, the wire electrode 60 is held between the pinch roller 84 and the feed roller 86. The wire electrode 60 is collected in the collection box 88.

[0014] When wire electrical discharge machining is performed, the machining tank 90 may store machining fluid. In this case, the table 62, the workpiece W, the upper wire guide 64, and the lower wire guide 66 are immersed in the machining fluid. The machining tank 90 is installed on the bed 92. Machining fluid is ejected into the space between the electrodes G from the upper nozzle of the upper wire guide 64 and the lower nozzle of the lower wire guide 66.

[0015] Figure 2 is a block diagram illustrating the configuration of the control device 20. The control device 20 includes an arithmetic unit 100 and a storage unit 102. The arithmetic unit 100 includes a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). In other words, the arithmetic unit 100 includes processing circuitry.

[0016] The memory unit 102 includes volatile memory such as RAM (Random Access Memory) and non-volatile memory such as ROM (Read Only Memory) or flash memory. The volatile memory is used as the processor's working memory. The non-volatile memory stores programs executed by the processor, predetermined processing conditions, boundary positions B where the plate thickness H of the workpiece W differs, and so on.

[0017] The machining conditions stored in the memory unit 102 include machining conditions for rough machining and machining conditions for finishing after rough machining. The machining conditions for finishing will be described later with reference to Figures 4 and 5. The boundary position B will be described later with reference to Figures 2, 3 and 4.

[0018] The calculation unit 100 includes a plate thickness detection unit 110, a boundary position determination unit 112, an electrode position detection unit 114, and a processing control unit 116. The calculation unit 100 executes a program stored in the storage unit 102, thereby realizing the plate thickness detection unit 110, the boundary position determination unit 112, the electrode position detection unit 114, and the processing control unit 116.

[0019] At least a portion of the plate thickness detection unit 110, boundary position determination unit 112, electrode position detection unit 114, and processing control unit 116 may be implemented by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array), or by an electronic circuit including discrete devices.

[0020] The plate thickness detection unit 110 detects the plate thickness H (see Figure 4) of the workpiece W during processing of the workpiece W along the processing path Rt. The plate thickness detection unit 110 detects the plate thickness H of the workpiece W based on the processing current flowing through the electrode gap G and the processing speed, which is the movement speed of the electrode position P of the wire electrode 60 moving along the processing path Rt. The processing current is proportional to the processing volume corresponding to the product of the processing speed and the plate thickness H. Therefore, the plate thickness H is obtained based on the processing current and the processing speed.

[0021] The current value of the machining current is obtained based on the voltage applied to the space between the electrodes G to generate the discharge, and the measured values ​​of voltage or current from a sensor (not shown). The machining speed is obtained based on the command value for the motor used to move the table 62, the value indicated by the encoder of the motor, or the value indicated by a linear encoder that detects the position of the moving member such as the table 62.

[0022] The plate thickness detection unit 110 detects the plate thickness H of the workpiece W before the workpiece W is processed along the processing path Rt using processing conditions including the boundary processing condition Cb (see Figures 4 and 5), which will be described later. In this embodiment, the plate thickness detection unit 110 detects the plate thickness H of the workpiece W during rough processing before the workpiece W is finished along the processing path Rt using processing conditions including the boundary processing condition Cb.

[0023] The boundary position determination unit 112 determines the position where the plate thickness H detected by the plate thickness detection unit 110 changes in the workpiece W as the boundary position B where the plate thickness H of the workpiece W differs. The boundary position determination unit 112 stores the boundary position B thus determined in the storage unit 102. The boundary position B stored in the storage unit 102 is used in the finishing process, which is performed after the roughing process, as described above.

[0024] The electrode position detection unit 114 detects the electrode position P of the wire electrode 60 on the processing path Rt. As described above, the wire electrode 60 moves relative to the workpiece W by moving the table 62. For example, the electrode position P of the wire electrode 60 can be detected based on the command value for the motor used to move the table 62, or the value indicated by the encoder of the motor.

[0025] The machining control unit 116 causes the wire electrical discharge machining machine 10 to machine the workpiece W using machining conditions that are pre-stored in the memory unit 102. These machining conditions include machining conditions for rough machining and machining conditions for finishing after rough machining. Both types of machining conditions are stored in the memory unit 102. Therefore, the machining control unit 116 can easily identify the machining conditions to be used for machining the workpiece W.

[0026] The machining conditions for finishing include the normal machining conditions Cn (see Figures 4 and 5) and boundary machining conditions Cb, which are different from the normal machining conditions Cn. The boundary machining conditions Cb are used when the relative distance between the boundary position B and the electrode position P stored in the memory unit 102, along the machining path Rt, is within a predetermined range. The normal machining conditions Cn are used when the relative distance is outside the predetermined range.

[0027] Figure 3 schematically illustrates the machining of a workpiece W with a changing plate thickness H. The wire electrode 60 is supported by an upper wire guide 64 and a lower wire guide 66. Figure 3 shows the upper die guide 70 of the upper wire guide 64 and the lower die guide 74 of the lower wire guide 66. The electrode gap G between the wire electrode 60 and the workpiece W is formed in the section of distance Dg between the two wire guides, which consist of the upper wire guide 64 and the lower wire guide 66.

[0028] A discharge occurs between the wire electrode 60 and the workpiece W, causing a machining current to flow through the gap G, and the workpiece W is machined. The electrode position P of the wire electrode 60 moves relative to the workpiece W along the machining path Rt, and the workpiece W is machined by the discharge.

[0029] In the example shown in Figure 3, the thickness H of the workpiece W is not uniform. The thickness H of the workpiece W changes twice along the machining path Rt. The position where the thickness H changes is the boundary position B described above. Figure 3 shows two boundary positions B along the machining path Rt, consisting of boundary position B=B1 and boundary position B=B2.

[0030] The workpiece W has a first portion W1 with a thickness H = H1, a second portion W2 with a thickness H = H2, and a third portion W3 with a thickness H = H3. At the boundary position B = B1 between the first portion W1 and the second portion W2 of the workpiece W, the thickness H of the workpiece W is different. At the boundary position B = B2 between the second portion W2 and the third portion W3 of the workpiece W, the thickness H of the workpiece W is different.

[0031] As the electrode position P of the wire electrode 60 moves along the processing path Rt, the processing of the workpiece W is performed by electrical discharge between the electrodes G. The processing conditions for this processing are set in advance. However, if the plate thickness H changes significantly during the processing of the workpiece W, the processing tends to become unstable. In that case, excessive electrical discharge may cause streaks to appear on the processed surface of the workpiece W at the boundary position B. In particular, the appearance of streaks during finishing is undesirable.

[0032] To reduce the occurrence of streaks at boundary position B, in this embodiment, the boundary machining condition Cb described above is used when the relative distance between boundary position B and electrode position P on the machining path Rt is within a predetermined range. An example of the boundary machining condition Cb will be described later with reference to Figure 5. When the relative distance is outside the predetermined range, the normal machining condition Cn described above is used. In other words, the machining conditions for finishing are selected according to the relative distance between boundary position B and electrode position P.

[0033] The thickness H of the workpiece W is detected by the thickness detection unit 110 during the machining of the workpiece W performed along the machining path Rt, before the workpiece W is machined along the machining path Rt using machining conditions including boundary machining conditions Cb and normal machining conditions Cn. In this embodiment, the thickness H of the workpiece W is detected by the thickness detection unit 110 during rough machining performed before the finish machining of the workpiece W. The machining conditions for rough machining are stored in advance by the storage unit 102, as described above.

[0034] The boundary position determination unit 112 determines the boundary position B at the position where the plate thickness H detected by the plate thickness detection unit 110 changes during rough machining. The boundary position B determined during rough machining is stored in the storage unit 102. This makes it possible to easily identify the boundary positions B where the plate thickness H of the workpiece W differs in advance, before the finishing process of the workpiece W.

[0035] Figure 4 is a diagram illustrating the finishing processing conditions that can be used depending on the relative distance between the boundary position B and the electrode position P. As described using Figure 3, in Figure 4, the workpiece W is arranged along the processing path Rt in the following order: a first part W1 with a plate thickness H=H1, a second part W2 with a plate thickness H=H2, and a third part W3 with a plate thickness H=H3.

[0036] The magnitude of the change in plate thickness H Dh at the boundary position B=B1 between the first part W1 and the second part W2 is |H1 - H2|. The magnitude of the change in plate thickness H Dh at the boundary position B=B2 between the second part W2 and the third part W3 is |H2 - H3|.

[0037] While the electrode position P of the wire electrode 60 is moving along the processing path Rt along the first part W1 of the workpiece W, the normal processing condition Cn is used. If the relative distance between the boundary position B=B1 and the electrode position P is less than a predetermined value Rd, the relative distance is considered to be within the predetermined range described above. As the electrode position P moves along the processing path Rt and approaches the boundary position B=B1, the relative distance becomes within the predetermined range. If the relative distance is within the predetermined range while the electrode position P is moving along the processing path Rt, the boundary processing condition Cb is used.

[0038] The predetermined range is determined in advance based on at least one of the distance Dg between the two wire guides and the amount of change Dh in the plate thickness H of the workpiece W at the boundary position B. This allows for a suitable determination of the predetermined range. The predetermined range can be defined using the predetermined value Rd described above. The predetermined value Rd can be set in the control device 20 by the user and / or manufacturer of the wire electrical discharge machining machine 10, so as to be changeable according to past machining results.

[0039] The larger the distance Dg between the two wire guides, the more likely the inter-electrode distance (G) between the wire electrode 60 and the workpiece W is to fluctuate. The larger the change in plate thickness H Dh, the more unstable the machining becomes, and therefore the more likely the inter-electrode distance is to fluctuate.

[0040] Therefore, the larger the distance Dg between the two wire guides, the larger the predetermined range. The larger the change in plate thickness H Dh, the larger the predetermined range.

[0041] When the electrode position P moves along the machining path Rt, passes through the boundary position B = B1, and moves away from the boundary position B = B1, eventually the relative distance goes outside the predetermined range. When the relative distance between the boundary position B = B1 and the electrode position P is greater than the predetermined value Rd, it is considered that the relative distance is outside the above-mentioned predetermined range. After the relative distance goes outside the predetermined range, normal machining conditions Cn are used while the electrode position P of the wire electrode 60 moves along the machining path Rt to the second portion W2 of the workpiece W.

[0042] When the electrode position P moves along the machining path Rt and approaches the boundary position B = B2, the relative distance comes within the predetermined range. While the electrode position P moves along the machining path Rt, when the relative distance is within the predetermined range, boundary machining conditions Cb are used.

[0043] When the electrode position P moves along the machining path Rt, passes through the boundary position B = B2, and moves away from the boundary position B = B2, eventually the relative distance goes outside the predetermined range. After the relative distance goes outside the predetermined range, normal machining conditions Cn are used while the electrode position P of the wire electrode 60 moves along the machining path Rt to the third portion W3 of the workpiece W.

[0044] FIG. 5 is a diagram illustrating a part of the parameters included in the normal machining conditions Cn and the boundary machining conditions Cb in finish machining. The boundary machining conditions Cb include the parameters shown in FIG. 5 as parameters in which fluctuations in the machining speed or fluctuations in the electrode position P of the wire electrode 60 can be suppressed more than in the normal machining conditions Cn.

[0045] The parameters include a machining speed gain. The parameters include the ejection amount of the machining fluid from the above-mentioned upper nozzle and / or lower nozzle. The parameters include the tension of the wire electrode 60 between the two wire guides composed of the upper wire guide 64 and the lower wire guide 66.

[0046] The machining speed gain Bg under the boundary machining conditions Cb is smaller than the machining speed gain Ng under the normal machining conditions Cn. As a result, during the machining of the workpiece W for which the boundary machining conditions Cb are used, fluctuations in the machining speed are suppressed, so fluctuations in the inter-electrode distance are suppressed. Therefore, the machining of the workpiece W is stabilized, and the generation of streaks on the machined surface of the workpiece W can be reduced.

[0047] The ejection amount Be of the machining fluid under the boundary machining conditions Cb is smaller than the ejection amount Ne of the machining fluid under the normal machining conditions Cn. As a result, during the machining of the workpiece W for which the boundary machining conditions Cb are used, fluctuations in the electrode position P of the wire electrode 60 are suppressed, so fluctuations in the inter-electrode distance are suppressed. Therefore, the machining of the workpiece W is stabilized, and the generation of streaks on the machined surface of the workpiece W can be reduced.

[0048] The tension Bt of the wire electrode 60 under the boundary machining conditions Cb is greater than the tension Nt of the wire electrode 60 under the normal machining conditions Cn. As a result, during the machining of the workpiece W for which the boundary machining conditions Cb are used, fluctuations in the electrode position P of the wire electrode 60 are suppressed, so fluctuations in the inter-electrode distance are suppressed. Therefore, the machining of the workpiece W is stabilized, and the generation of streaks on the machined surface of the workpiece W can be reduced.

[0049] Thus, the boundary machining conditions Cb include parameters in which fluctuations in the machining speed or fluctuations in the electrode position P can be suppressed more than under the normal machining conditions Cn. Therefore, the generation of streaks on the machined surface of the workpiece W due to fluctuations in the inter-electrode distance can be effectively reduced.

[0050] FIG. 6 is a flowchart illustrating a processing procedure regarding a control method of the wire electrical discharge machining machine 10 in rough machining of the workpiece W. This processing procedure is performed when there is an execution command for rough machining of the workpiece W to the control device 20. This processing procedure is performed by executing a program stored in the storage unit 102 of the control device 20. When this processing procedure is started, the machining control unit 116 causes the wire electrical discharge machining machine 10 to machine the workpiece W using the machining conditions for rough machining.

[0051] In step S1, the plate thickness detection unit 110 detects the plate thickness H of the workpiece W during rough machining along the machining path Rt. In step S2, the boundary position determination unit 112 determines whether the plate thickness H detected in step S1 has changed during rough machining. If the answer in step S2 is YES, the process proceeds to step S3. If the answer in step S2 is NO, the process returns to step S1. Note that if the amount of change Dh in plate thickness H is less than a predetermined amount, it may be determined that the plate thickness H has not changed.

[0052] In step S3, the boundary position determination unit 112 determines the boundary position B as the position where the plate thickness H determined in step S2 changes. The boundary position determination unit 112 stores the determined boundary position B in the storage unit 102. In step S4, the processing control unit 116 determines whether or not rough machining of the workpiece W has been completed. If the answer in step S4 is YES, this processing procedure ends. If the answer in step S4 is NO, this processing procedure returns to step S1.

[0053] Figure 7 is a flowchart illustrating a processing procedure for controlling the wire electrical discharge machining machine 10 during the finishing of a workpiece W. This processing procedure is performed when the control device 20 receives an execution command for finishing the workpiece W. This processing procedure is performed by executing a program stored in the storage unit 102 of the control device 20. When this processing procedure is started, the machining control unit 116 causes the wire electrical discharge machining machine 10 to machine the workpiece W using the normal machining conditions Cn among the machining conditions for finishing.

[0054] In step S21, the electrode position detection unit 114 detects the electrode position P of the wire electrode 60 on the processing path Rt. In step S22, the processing control unit 116 determines whether the relative distance between the boundary position B stored by the storage unit 102 and the electrode position P of the wire electrode 60 on the processing path Rt is within a predetermined range. If the answer in step S22 is YES, the process proceeds to step S41. If the answer in step S22 is NO, the process proceeds to step S23.

[0055] In step S23, the machining control unit 116 causes the wire electrical discharge machining machine 10 to machine the workpiece W using the normal machining condition Cn. If the process in step S23 is completed, the process proceeds to step S24. In step S41, the machining control unit 116 causes the wire electrical discharge machining machine 10 to machine the workpiece W using the boundary machining condition Cb. If the process in step S41 is completed, the process proceeds to step S24.

[0056] In step S24, the machining control unit 116 determines whether the finishing of the workpiece W has been completed. If the answer in step S24 is YES, this process procedure ends. If the answer in step S24 is NO, this process procedure returns to step S21.

[0057] In this embodiment, when the relative distance between the boundary position B and the electrode position P on the machining path Rt is within a predetermined range, the wire electrical discharge machining machine 10 processes the workpiece W using boundary machining conditions Cb, which are different from the normal machining conditions Cn. Therefore, the occurrence of streaks on the machined surface of the workpiece W can be reduced at boundary positions B where the plate thickness H of the workpiece W is different.

[0058] The embodiments described above may be modified as follows. In the following modifications, explanations that overlap with the embodiments will be omitted.

[0059] (Modification 1) In the embodiment described above, the storage unit 102 stores normal processing conditions Cn and boundary processing conditions Cb as processing conditions for finishing, but is not limited to this. In this modification 1, the storage unit 102 stores only normal processing conditions Cn as processing conditions for finishing. The parameters of the boundary processing conditions Cb may be determined by multiplying the parameters included in the normal processing conditions Cn by a ratio.

[0060] Figure 8 illustrates an example in which the parameters of the boundary machining condition Cb are determined by multiplying the parameters included in the normal machining condition Cn by a ratio. The normal machining condition Cn shown in Figure 8 is equal to the normal machining condition Cn shown in Figure 5.

[0061] The parameters for the boundary processing conditions Cb shown in Figure 8 are obtained by the processing control unit 116 multiplying the parameters included in the normal processing conditions Cn by a ratio. This ratio is predetermined according to the amount of change Dh in the thickness H of the workpiece W at the boundary position B. If the parameter is the processing speed gain or the amount of processing fluid ejected, the ratio is smaller as the amount of change Dh in the thickness H increases. If the parameter is the tension of the wire electrode 60, the ratio is larger as the amount of change Dh in the thickness H increases.

[0062] The machining speed gain Bg under boundary machining condition Cb is obtained by multiplying the machining speed gain Ng under normal machining condition Cn by a ratio Kg. The ratio Kg satisfies the condition 0 < Kg < 1. As a result, fluctuations in machining speed are suppressed during machining of the workpiece W using boundary machining condition Cb, and therefore fluctuations in the inter-pole distance are suppressed. Consequently, machining of the workpiece W becomes more stable, and the occurrence of streaks on the machined surface of the workpiece W can be reduced.

[0063] The amount of processing fluid ejected Be under boundary processing condition Cb is obtained by multiplying the amount of processing fluid ejected Ne under normal processing condition Cn by a ratio Ke. The ratio Ke satisfies the condition 0 < Ke < 1. As a result, during processing of the workpiece W using boundary processing condition Cb, fluctuations in the electrode position P of the wire electrode 60 are suppressed, and therefore fluctuations in the inter-electrode distance are suppressed. Consequently, the processing of the workpiece W is stabilized, and the occurrence of streaks on the processed surface of the workpiece W can be reduced.

[0064] The tension Bt of the wire electrode 60 under boundary processing condition Cb is obtained by multiplying the tension Nt of the wire electrode 60 under normal processing condition Cn by a ratio Kt. The ratio Kt satisfies condition 1 < Kt < Ktu. The upper limit Ktu corresponds to the maximum tension at which the wire electrode 60 does not break. As a result, during processing of the workpiece W using boundary processing condition Cb, fluctuations in the electrode position P of the wire electrode 60 are suppressed, and therefore fluctuations in the inter-electrode distance are suppressed. Consequently, the processing of the workpiece W is stabilized, and the occurrence of streaks on the processed surface of the workpiece W can be reduced.

[0065] In this modified example 1, the memory unit 102 stores only the normal machining conditions Cn as machining conditions for finishing. Therefore, it is unnecessary to pre-store the boundary machining conditions Cb in the memory unit 102. This reduces the man-hours required for this process and suppresses the occurrence of machining defects due to errors in this process.

[0066] (Modification 2) Both the normal processing condition Cn and the boundary processing condition Cb may differ depending on the plate thickness H. In the example shown in Figure 4, for processing in the region of the first part W1 of the workpiece W where the relative distance between the boundary position B=B1 and the electrode position P is outside a predetermined range, the normal processing condition Cn is used. This normal processing condition Cn is determined according to the plate thickness H=H1 of the workpiece W. This normal processing condition Cn is referred to as the normal processing condition Cn1 corresponding to the first part W1.

[0067] In the example shown in Figure 4, in the second portion W2 of the workpiece W, the normal processing condition Cn is used when processing in a region where the relative distance between boundary position B=B1 and electrode position P is outside a predetermined range, and the relative distance between boundary position B=B2 and electrode position P is also outside a predetermined range. This normal processing condition Cn is determined according to the plate thickness H=H2 of the workpiece W. This normal processing condition Cn is referred to as the normal processing condition Cn2 corresponding to the second portion W2.

[0068] In the example shown in Figure 4, for machining in the region of the third portion W3 of the workpiece W where the relative distance between the boundary position B = B2 and the electrode position P is outside a predetermined range, the normal machining condition Cn is used. This normal machining condition Cn is determined according to the plate thickness H = H3 of the workpiece W. This normal machining condition Cn is referred to as the normal machining condition Cn3 corresponding to the third portion W3.

[0069] If H1, H2, and H3 are all different values, then the normal processing conditions Cn1, Cn2, and Cn3 may also be different. In that case, it becomes possible to process the workpiece W according to the plate thickness H.

[0070] Furthermore, in the example shown in Figure 4, a boundary machining condition Cb is used when machining a region of the workpiece W where the relative distance between the boundary position B = B1 and the electrode position P is within a predetermined range. This boundary machining condition Cb is determined according to the normal machining conditions Cn1 and Cn2 used before and after the region, and the change in the plate thickness H of the workpiece W, Dh = Dh1. This boundary machining condition Cb is defined as boundary machining condition Cb1 corresponding to boundary position B = B1.

[0071] In the example shown in Figure 4, a boundary machining condition Cb is used when machining a region of the workpiece W where the relative distance between the boundary position B = B2 and the electrode position P is within a predetermined range. This boundary machining condition Cb is determined according to the normal machining conditions Cn2 and Cn3 used before and after the region, and the change in the plate thickness H of the workpiece W, Dh = Dh2. This boundary machining condition Cb is designated as the boundary machining condition Cb2 corresponding to the boundary position B = B2.

[0072] If at least Dh1 and Dh2 are different values, the boundary processing conditions Cb1 and Cb2 may also be different. In that case, it becomes possible to process the workpiece W according to the amount of change Dh in the plate thickness H.

[0073] In this modified example 2, when processing in a region where the relative distance between the boundary position B and the electrode position P is outside a predetermined range, it becomes possible to process the workpiece W according to the plate thickness H. Furthermore, when processing in a region where the relative distance between the boundary position B and the electrode position P is within a predetermined range, it becomes possible to process the workpiece W according to the amount Dh of change in plate thickness H. Therefore, the processing quality of the workpiece W can be further improved.

[0074] With regard to the embodiments described above, the following additional information is disclosed.

[0075] (Note 1) The control device (20) of the present disclosure is a control device for a wire electrical discharge machine (10) that processes a workpiece (W) by moving a wire electrode (60) relative to the workpiece along a processing path (Rt) and performing an electrical discharge between the electrode (G) of the wire electrode and the workpiece, comprising: a storage unit (102) that stores boundary positions (B) where the plate thickness (H) of the workpiece is different; an electrode position detection unit (114) that detects the electrode position (P) of the wire electrode; and a processing control unit (116) that causes the wire electrical discharge machine to process the workpiece using boundary processing conditions (Cb) different from the normal processing conditions (Cn) used when the relative distance on the processing path is outside the predetermined range, when the relative distance between the boundary position and the electrode position is within a predetermined range.

[0076] (Note 2) The control device described in Note 1, wherein the predetermined range may be predetermined based on at least one of the distance (Dg) between the two wire guides (64, 66) supporting the wire electrode and the amount of change in the plate thickness (Dh) at the boundary position.

[0077] (Note 3) In the control device described in Note 1 or 2, the boundary machining conditions may include parameters that can suppress fluctuations in the machining speed, which is the moving speed of the electrode position, or fluctuations in the electrode position, more than the normal machining conditions.

[0078] (Note 4) A control device according to any one of Notes 1 to 3, further comprising: a plate thickness detection unit (110) that, before the workpiece is processed along the processing path using processing conditions including the boundary processing conditions, detects the plate thickness based on the processing current flowing between the electrodes and the processing speed which is the speed at which the electrode positions move during processing of the workpiece along the processing path; and a boundary position determination unit (112) that determines the position in the workpiece where the plate thickness detected by the plate thickness detection unit changes as the boundary position and stores the boundary position in the storage unit.

[0079] (Note 5) A control device according to any one of Notes 1 to 4, wherein the storage unit may further store the normal processing conditions and the boundary processing conditions.

[0080] (Note 6) A control device according to any one of Notes 1 to 4, wherein the storage unit further stores the normal processing conditions, and the processing control unit determines the parameters to be included in the boundary processing conditions by multiplying the parameters included in the normal processing conditions by a ratio (Kg, Ke, Kt) corresponding to the amount of change in the plate thickness at the boundary position.

[0081] (Note 7) The control method of the present disclosure is a control method for a wire electrical discharge machine that processes a workpiece by performing an electrical discharge between the electrodes of the wire electrode and the workpiece while moving the wire electrode relative to the workpiece along a processing path, comprising: an electrode position detection step of detecting the electrode position of the wire electrode; and a processing control step of causing the wire electrical discharge machine to process the workpiece using boundary processing conditions different from the normal processing conditions used when the relative distance is outside the predetermined range, when the relative distance between the electrode position and a boundary position of the workpiece with different plate thicknesses stored in a storage unit is within a predetermined range.

[0082] 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. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given 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.

[0083] 10...Wire EDM machine 20...Control device 30...Power supply for machining 60...Wire electrode 62...Table 64...Upper wire guide 66...Lower wire guide 68...Upper guide block 70...Upper die guide 72...Lower guide block 74...Lower die guide 76...Wire bobbin 78...Roller 84...Pinch roller 86...Feed roller 88...Collection box 90...Machining tank 92...Bed 100...Calculation unit 102...Storage unit 110...Plate thickness detection unit 112...Boundary position determination unit 114...Electrode position detection unit 116...Machining control unit

Claims

1. A control device for a wire electrical discharge machine that processes a workpiece by performing an electrical discharge between the electrodes of the wire electrode and the workpiece while moving the wire electrode relative to the workpiece along a processing path, comprising: a storage unit that stores boundary positions of the workpiece with different plate thicknesses; an electrode position detection unit that detects the electrode position of the wire electrode; and a processing control unit that causes the wire electrical discharge machine to process the workpiece using boundary processing conditions different from the normal processing conditions used when the relative distance on the processing path is outside the predetermined range, when the relative distance between the boundary position and the electrode position is within a predetermined range.

2. A control device according to claim 1, wherein the predetermined range is predetermined based on at least one of the distance between two wire guides supporting the wire electrode and the amount of change in the plate thickness at the boundary position.

3. A control device according to claim 1 or 2, wherein the boundary machining conditions include parameters that can suppress fluctuations in the machining speed, which is the moving speed of the electrode position, or fluctuations in the electrode position, compared to the normal machining conditions.

4. A control device according to any one of claims 1 to 3, further comprising: a plate thickness detection unit that, before the workpiece is processed along the processing path using processing conditions including the boundary processing conditions, detects the plate thickness based on the processing current flowing between the electrodes and the processing speed which is the movement speed of the electrode positions during processing of the workpiece along the processing path; and a boundary position determination unit that determines the position in the workpiece where the plate thickness detected by the plate thickness detection unit changes as the boundary position and stores the boundary position in the storage unit.

5. A control device according to any one of claims 1 to 4, wherein the storage unit further stores the normal processing conditions and the boundary processing conditions.

6. A control device according to any one of claims 1 to 4, wherein the storage unit further stores the normal processing conditions, and the processing control unit determines the parameters to be included in the boundary processing conditions by multiplying the parameters included in the normal processing conditions by a ratio corresponding to the amount of change in the plate thickness at the boundary position.

7. A control method for a wire electrical discharge machine that processes a workpiece by performing an electrical discharge between the electrodes of the wire electrode and the workpiece while moving the wire electrode relative to the workpiece along a processing path, comprising: an electrode position detection step for detecting the electrode position of the wire electrode; and a processing control step for causing the wire electrical discharge machine to process the workpiece using boundary processing conditions different from the normal processing conditions used when the relative distance is outside the predetermined range, when the relative distance between the electrode position and a boundary position of the workpiece with different plate thicknesses stored in a memory unit is within a predetermined range.

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