Control device and control method for wire electrical discharge machine

Abstract

A control device (30) for a wire electrical discharge machining (10) includes: a machining control unit (310) that changes a first control quantity (V) in an inner corner interval (CI) and changes a second control quantity (F) in an outer corner interval (CO); and an adjustment unit (320) that adjusts the current first control quantity and the current second control quantity respectively in a repetition interval (DS) where the first control quantity and the second control quantity repeatedly change. In the repetition interval, the machining control unit controls the wire electrical discharge machining according to the adjusted first control quantity and the adjusted second control quantity.

Description

Technical Field

[0001] This invention relates to a control device and control method for a wire electrical discharge machining (EDM) machine. Background Technology

[0002] International Publication No. 2015 / 063932 discloses a wire electrical discharge machining apparatus that improves the machining accuracy of corner shapes by calculating appropriate corner speed commands. Summary of the Invention

[0003] In online electrical discharge machining (EDM), in addition to controlling the machining speed, multiple controls are sometimes performed, such as controlling the discharge voltage and discharge frequency. In the EDM apparatus disclosed in International Publication No. 2015 / 063932, when machining the corner shape based on the line discharge is continuous, the repetition of multiple controls is not considered. Therefore, there is a problem that the improvement in machining accuracy remains limited.

[0004] The purpose of this invention is to solve the above-mentioned problems.

[0005] The first aspect of the present invention is a control device for a wire electrical discharge machining (EDM) machine, which moves a wire electrode relative to a workpiece along a machining path while generating a discharge between the wire electrode and the workpiece to machine the workpiece. The control device comprises a machining control unit that controls the EDM machine according to a plurality of control quantities based on reference machining conditions. Specifically, in an inner corner section, the control unit changes at least one first control quantity among the plurality of control quantities based on machining conditions for the inner corner section. In an outer corner section immediately following the inner corner section, the control unit changes a control quantity different from the first control quantity based on the machining conditions for the outer corner section. The wire electrical discharge machining (EDM) machine is controlled by at least one change in a second control quantity; and an adjustment unit calculates, within a repetition interval where the first control quantity and the second control quantity repeatedly change, a first ratio (the ratio of the current change in the first control quantity to the maximum change in the first control quantity) and a second ratio (the ratio of the current change in the second control quantity to the maximum change in the second control quantity), and adjusts the current first control quantity and the current second control quantity based on the first ratio and the second ratio, respectively. Within the repetition interval where the first control quantity and the second control quantity repeatedly change, the machining control unit controls the EDM machine according to the adjusted first control quantity and the adjusted second control quantity.

[0006] The second aspect of the present invention is a control method for a wire electrical discharge machining (EDM) machine, which moves a wire electrode relative to a workpiece along a machining path while simultaneously generating an electrical discharge between the wire electrode and the workpiece to machine the workpiece. The control method for the wire EDM machine includes the following machining control: controlling the wire EDM machine according to a plurality of control quantities based on reference machining conditions; and controlling the wire EDM machine by changing at least one first control quantity among the plurality of control quantities in an inner corner interval based on machining conditions used in the inner corner interval; and controlling the wire EDM machine by changing at least one of the plurality of control quantities that differs from the first control quantity in an outer corner interval immediately following the inner corner interval, based on machining conditions used in the outer corner interval. A second control variable is used to control the wire electrical discharge machine, and the following adjustments are made: In the repetition interval where the first control variable and the second control variable repeatedly change, the ratio of the current change of the first control variable to the maximum change of the first control variable (i.e., the first ratio) and the ratio of the current change of the second control variable to the maximum change of the second control variable (i.e., the second ratio) are calculated. Based on the first ratio and the second ratio, the current first control variable and the current second control variable are adjusted respectively. When performing the machining control, in the repetition interval where the first control variable and the second control variable repeatedly change, the wire electrical discharge machine is controlled according to the adjusted first control variable and the adjusted second control variable.

[0007] According to the present invention, the accuracy of wire discharge machining when the corner section is continuous is improved. Attached Figure Description

[0008] Figure 1 This is a diagram showing the configuration of a wire electrical discharge machining (EDM) machine, including a control unit.

[0009] Figure 2 yes Figure 1 The diagram shown is a functional block diagram of a wire electrical discharge machining (EDM) machine.

[0010] Figure 3 This is a diagram illustrating an example of a corner path.

[0011] Figure 4 This is a diagram showing different control repetitions related to the pulse voltage applied between the poles.

[0012] Figure 5 This is a flowchart illustrating the control processing of a wire electrical discharge machine performed by a control device in one embodiment.

[0013] Figure 6 This is a flowchart illustrating the control processing of the wire electrical discharge machine performed by the control device in Variation Example 1. Detailed Implementation

[0014] Figure 1 This diagram illustrates the configuration of a wire electrical discharge machining (EDM) machine 10, including a control unit 30. The EDM machine 10 performs EDM machining on the workpiece by generating a discharge through the electrode space formed by the wire electrode 14 and the workpiece. The EDM machine 10 performs EDM machining along a machining path specified by a predetermined program, while the wire electrode 14 is relatively moved relative to the workpiece. The relative movement of the wire electrode 14 and the workpiece is achieved, for example, by moving the worktable 12 that supports the workpiece.

[0015] The wire EDM machine 10 includes an upper wire guide 16, a lower wire guide 18, an upper guide block 20, and a lower guide block 22. The upper wire guide 16 supports the wire electrode 14 on the upper side (+Z direction side) of the worktable 12. The lower wire guide 18 supports the wire electrode 14 on the lower side (-Z direction side) of the worktable 12. The upper wire guide 16 is mounted on the upper guide block 20. The lower wire guide 18 is mounted on the lower guide block 22. The wire electrode 14 is supplied from the winding tube 24 in the feed direction at a predetermined speed. The wire electrode 14 is held by the clamping roller 44 and the feed roller 46 via the roller 36, the upper wire guide 16, and the lower wire guide 18, and is recovered by the recovery box 26. Furthermore, the wire EDM machine 10 includes a processing power supply 28 for supplying voltage between the electrodes and a control device 30.

[0016] The control device 30 includes processing circuitry and a memory for storing programs. The processing circuitry executes the program, thus functioning as the control device 30 in this embodiment. The control device 30 controls the processing of the workpiece by the wire electrical discharge machining (EDM) machine 10. The memory includes volatile memory such as RAM and non-volatile memory such as ROM and flash memory. The processing circuitry includes a processor such as a CPU. Figure 1 The X, Y, and Z directions shown are orthogonal to each other, and the -Z direction is the direction of gravity.

[0017] In the case of wire electrical discharge machining, the machining tank 34 can also store machining fluid. At this time, the worktable 12, the workpiece, the upper wire guide 16 and upper guide block 20, and the lower wire guide 18 and lower guide block 22 are immersed in the machining fluid. The upper wire guide 16 can also spray machining fluid into the electrode space formed by the wire electrode 14 and the workpiece. This prevents machining chips (sludge) from floating in the electrode space, resulting in improved machining accuracy. Additionally, the lower wire guide 18 can also spray machining fluid into the electrode space. The machining tank 34 is mounted on the base 38.

[0018] Figure 2 yes Figure 1 The functional block diagram of the wire electrical discharge machining machine 10 is shown. Figure 2 express Figure 1This is part of the configuration of the wire electrical discharge machining (EDM) machine 10 shown. Figure 2 The text also shows that it was not in Figure 1 The workpiece W, displacement driver 40, feed drive unit 32, and pump 48 are shown in the diagram. The workpiece W is mounted on the worktable 12. The machining power supply 28 repeatedly applies pulse voltages to the electrode gap G formed by the wire electrode 14 and the workpiece W.

[0019] The displacement drive unit 40 drives the worktable 12 to move the wire electrode 14 relative to the workpiece W in the X and Y directions. The displacement drive unit 40 includes an X-motor, a Y-motor, an X-drive transmission mechanism, and a Y-drive transmission mechanism. The X-motor moves the worktable 12 in the X direction. The Y-motor moves the worktable 12 in the Y direction. The X-drive transmission mechanism converts the rotary motion of the X-motor into linear motion of the worktable 12 in the X direction. The Y-drive transmission mechanism converts the rotary motion of the Y-motor into linear motion of the worktable 12 in the Y direction. Both the X-drive transmission mechanism and the Y-drive transmission mechanism are composed of ball screws and nuts mounted on the worktable 12. Furthermore, an encoder (rotational position detection sensor) for detecting rotational position is provided on each of the X-motor and Y-motor.

[0020] Alternatively, a displacement drive unit that drives the upper guide block 20 and the lower guide block 22 in the X and Y directions can be provided instead of the displacement drive unit 40. Furthermore, in addition to the displacement drive unit 40, other displacement drive units that drive the upper guide block 20 and the lower guide block 22 in the X and Y directions can also be provided.

[0021] The delivery drive unit 32 includes a roller 36 and a delivery motor. The roller 36, by rotating, delivers the wire electrode 14 wound on the winding tube 24 to the workpiece W. The delivery motor rotates the roller 36. An encoder (rotation position detection sensor) is installed on the delivery motor to detect the rotational position.

[0022] Pump 48 draws in machining fluid purified by a machining fluid supply device (not shown) and supplies the drawn-in machining fluid to the upper guide member 16. The upper guide member 16 sprays the machining fluid into the electrode space G. Pump 48 can also supply the drawn-in machining fluid to the lower guide member 18. The lower guide member 18 sprays the machining fluid into the electrode space G.

[0023] In this embodiment, a wire electrical discharge machining (EDM) machine 10 is described that processes the workpiece W along a corner path including corner intervals of different shapes. In this embodiment, the corner intervals of different shapes are the inner corner interval and the outer corner interval immediately following the inner corner interval. The control device 30 of this embodiment includes a processing control unit 310 and an adjustment unit 320. At least a portion of the processing control unit 310 and the adjustment unit 320 may also be implemented using an ASIC, FPGA, or other integrated circuits.

[0024] The machining control unit 310 controls the feed drive unit 32, the displacement drive unit 40, the machining power supply 28, and the pump 48. By controlling the feed drive unit 32, the machining control unit 310 feeds the wire electrode 14, which is used for electrical discharge machining of the workpiece W, from the upper wire guide 16 to the lower wire guide 18 at a feed rate specified by the machining conditions. By controlling the displacement drive unit 40, the machining control unit 310 moves the wire electrode 14 relative to the workpiece W along a machining path specified by the machining program in the X and Y directions. The machining control unit 310 can also move the wire electrode 14 relative to the workpiece W according to the machining speed specified by the machining conditions. Furthermore, the machining control unit 310 can also control the pump 48 to spray machining fluid into the inter-electrode G based on the spray flow rate specified by the machining conditions, from at least one of the upper wire guide 16 and the lower wire guide 18.

[0025] The machining control unit 310 controls the machining power supply 28, which repeatedly applies pulse voltages to the electrode gap G. The machining control unit 310 can also apply pulse voltages of a magnitude specified by the machining conditions to the electrode gap G. The machining control unit 310 can also apply pulse voltages to the electrode gap G with a number of pulses specified by the machining conditions. Furthermore, in this embodiment, "number of pulses" refers to the number of pulses per unit time.

[0026] The machining control unit 310 controls at least one of the machining power supply 28 and the displacement drive unit 40 according to multiple control quantities specified by the machining conditions. These multiple control quantities include, for example, pulse voltage control quantities, pulse number control quantities, machining speed control quantities, and machining fluid control quantities. The pulse voltage control quantity controls the magnitude of the pulse voltage applied to the electrode space G when the machining power supply 28 discharges to a magnitude specified by the machining conditions. The pulse number control quantity controls the number of pulses per unit time of the pulse voltage applied to the electrode space G when the machining power supply 28 discharges to a number of pulses specified by the machining conditions. The machining speed control quantity controls the speed at which the displacement drive unit 40 processes the workpiece W to a machining speed specified by the machining conditions. The machining fluid control quantity controls the flow rate per unit time of the machining fluid supplied to the electrode space G in the machining tank 34 when the machining power supply 28 discharges to a flow rate specified by the machining conditions.

[0027] In the inner corner section, the machining control unit 310 changes a first control quantity based on the machining conditions for the inner corner section. In the outer corner section, the machining control unit 310 changes a second control quantity based on the machining conditions for the outer corner section. The first control quantity and the second control quantity are different control quantities. In this embodiment, the first control quantity is a pulse voltage control quantity, and the second control quantity is a pulse count control quantity.

[0028] The adjustment unit 320 adjusts the repeatedly changing control quantity within a repeating interval where a portion of the control quantity among a plurality of control quantities repeatedly changes. In this embodiment, the first control quantity and the second control quantity repeatedly change within the repeating interval.

[0029] Figure 3 This is a diagram illustrating an example of a corner path. For example... Figure 3 As shown, the machining path RT has a straight path, a corner path immediately following the straight path, and a straight path immediately following the corner path. The corner path has an inner corner interval CI and an outer corner interval CO immediately following the inner corner interval CI. The machining path RT, in which the wire electrode 14 moves relative to the workpiece W, begins with the straight path interval before position PA. Then comes the curved inner corner interval CI from position PA to position PB. Next is the curved outer corner interval CO from position PB to position PC. There is a straight path interval before position PC. In the inner corner interval CI, the surface of the workpiece W is curved in a way that covers the machining path RT. Conversely, in the outer corner interval CO, the surface of the workpiece W is curved in a way that warps toward the machining path RT.

[0030] Before the in-line electrode 14 enters the corner path, the machining control unit 310 controls the wire electrical discharge machine 10 according to multiple control quantities based on reference machining conditions. In this embodiment, the multiple control quantities include at least a first control quantity V and a second control quantity F. The machining control unit 310 sets the reference control quantity V0 to the first control quantity V based on the reference machining conditions. The machining control unit 310 sets the reference control quantity F0 to the second control quantity F based on the reference machining conditions.

[0031] When the wire electrode 14 moves relative to the workpiece W and passes through position PA, the machining control unit 310, based on the machining conditions for the inner corner interval CI, gradually changes the first control quantity V from the reference control quantity V0 until the first control quantity V reaches the maximum control quantity VH. The maximum control quantity VH is specified by the machining conditions for the inner corner interval CI. Furthermore, for control quantities other than the first control quantity V, the control quantities based on the reference machining conditions are used directly.

[0032] When the wire electrode 14 moves relative to the workpiece W and passes through position PB on the machining path RT, the machining control unit 310 gradually changes the first control quantity V from the maximum control quantity VH until the first control quantity V reaches the reference control quantity V0. Similarly, when the wire electrode 14 moves relative to the workpiece W and passes through position PB, the machining control unit 310 gradually changes the second control quantity F from the reference control quantity F0 based on the machining conditions used in the outer corner interval CO until the second control quantity F reaches the maximum control quantity FH. The maximum control quantity FH is specified by the machining conditions used in the outer corner interval CO. In addition, regarding control quantities other than the second control quantity F, except for the first control quantity V that changes towards the reference control quantity V0, control quantities based on the reference machining conditions are used directly.

[0033] When the wire electrode 14 moves relative to the workpiece W and reaches position PB, a repetitive interval DS occurs, where machining control is performed according to a first control amount V exceeding the reference control amount V0 and a second control amount F exceeding the reference control amount F0. For example... Figure 3 As shown, the repeating interval DS is the interval from position PB to position PD on the machining path RT. This repeating interval DS is the interval where the first control quantity V differs from the reference control quantity V0, and the second control quantity F differs from the reference control quantity F0. That is, the repeating interval DS is the interval where the first control quantity V changes from the reference control quantity V0, and the second control quantity F changes from the reference control quantity F0.

[0034] When the wire electrode 14 moves relative to the workpiece W and passes through position PD, the machining control unit 310 maintains the maximum control quantity FH as the second control quantity F. When the wire electrode 14 moves relative to the workpiece W and passes through position PC, the machining control unit 310 gradually changes the second control quantity F from the maximum control quantity FH until the second control quantity F reaches the reference control quantity F0.

[0035] Figure 4 This is a graph showing the different control repetitions related to the pulse voltage applied between the electrodes G. Curves 510 and 560 show the changes in the first control quantity V and the second control quantity F as the relative position of the line electrode 14 changes relative to the workpiece W. However, different control repetitions within the repetition interval DS are not considered in curves 510 and 560.

[0036] The relative position of the wire electrode 14, moved by electrical discharge machining, with respect to the workpiece W is determined as the position on the machining path RT specified by the machining program. As described above, the first control quantity V increases according to the machining conditions used in the inner corner interval CI, and the second control quantity F increases according to the machining conditions used in the outer corner interval CO. As shown in curves 510 and 560, in the interval of the straight path before position PA on the machining path RT, the first control quantity V and the second control quantity F are equal to the reference control quantity V0 and the reference control quantity F0, respectively.

[0037] As shown in curve 510, in the inner corner interval CI, the first control quantity V gradually increases from the reference control quantity V0 to the maximum control quantity VH, and then maintains the maximum control quantity VH. As shown in curve 560, in the same inner corner interval CI, the second control quantity F maintains the reference control quantity F0.

[0038] As shown in curve 560, in the outer corner interval CO, the second control quantity F gradually increases from the reference control quantity F0 to reach the maximum control quantity FH, and then maintains the maximum control quantity FH. As shown in curve 510, in the repeat interval DS, the first control quantity V gradually decreases from the maximum control quantity VH to reach the reference control quantity V0. As shown in curve 510, after machining in the repeat interval DS is completed, in the interval from position PD to position PC on the machining path RT contained in the outer corner interval CO, the first control quantity V maintains the reference control quantity V0. In the example shown in curve 560, the position where the second control quantity F reaches the maximum control quantity FH is before position PD and within the repeat interval DS. However, the position where the second control quantity F reaches the maximum control quantity FH can also be before position PD and outside the repeat interval DS.

[0039] As shown by curve 510, in the section of the straight path preceding position PC on the machining path RT, the first control quantity V maintains the reference control quantity V0. As shown by curve 560, in the same section of the straight path, the second control quantity F gradually decreases from the maximum control quantity FH to reach the reference control quantity F0. As shown by curve 560, in the section after the second control quantity F on the machining path RT reaches the reference control quantity F0, the second control quantity F maintains the reference control quantity F0.

[0040] As shown in curve 510, the difference between the current first control quantity Vk and the reference control quantity V0 at the current position Pk on the processing path RT is taken as the current change quantity ΔVk. As shown in curve 510, the difference between the maximum control quantity VH of the first control quantity V and the reference control quantity V0 is taken as the maximum change quantity ΔVmax. The current change quantity ΔVk and the maximum change quantity ΔVmax are represented by equations (1) and (2). The current change quantity ΔVk is the change of the current first control quantity Vk relative to the reference control quantity V0. The maximum change quantity ΔVmax is the change of the maximum control quantity VH relative to the reference control quantity V0. The adjustment unit 320 calculates the first ratio RVk as the ratio of the current change quantity ΔVk to the maximum change quantity ΔVmax of the first control quantity V. As shown in equation (3), the first ratio RVk is the value of the ratio of the current change quantity ΔVk to the maximum change quantity ΔVmax. For convenience, Figure 4 The first ratio RVk is displayed as a percentage of the ratio of the current change ΔVk to the maximum change ΔVmax.

[0041] ΔVk=Vk-V0 …(1)

[0042] ΔVmax=VH-V0 …(2)

[0043] RVk=ΔVk / ΔVmax …(3)

[0044] As shown in curve 560, the difference between the current second control quantity Fk and the reference control quantity F0 at the current position Pk on the processing path RT is taken as the current change quantity ΔFk. As shown in curve 560, the difference between the maximum control quantity FH of the second control quantity F and the reference control quantity F0 is taken as the maximum change quantity ΔFmax. The current change quantity ΔFk and the maximum change quantity ΔFmax are represented by equations (4) and (5). The current change quantity ΔFk is the change of the current second control quantity Fk relative to the reference control quantity F0. The maximum change quantity ΔFmax is the change of the maximum control quantity FH relative to the reference control quantity F0. The adjustment unit 320 calculates the second ratio RFk as the ratio of the current change quantity ΔFk to the maximum change quantity ΔFmax of the second control quantity F. As shown in equation (6), the second ratio RFk is the value of the ratio of the current change quantity ΔFk to the maximum change quantity ΔFmax. For convenience, Figure 4 The second ratio RFk is displayed as a percentage of the ratio of the current change ΔFk to the maximum change ΔFmax.

[0045] ΔFk=Fk-F0 …(4)

[0046] ΔFmax=FH-F0 …(5)

[0047] RFk=ΔFk / ΔFmax …(6)

[0048] Curve 610 represents the change in position on the machining path RT corresponding to the first ratio RVk calculated by the adjustment unit 320 using equation (3). Curve 660 represents the change in position on the machining path RT corresponding to the second ratio RFk calculated by the adjustment unit 320 using equation (6). If equations (3) and (6) are modified using equations (1) and (4) respectively, then the first control quantity Vk shown in curve 510 and the second control quantity Fk shown in curve 560 are represented by equations (7) and (8) respectively.

[0049] Vk=V0+ΔVmax×RVk …(7)

[0050] Fk=F0+ΔFmax×RFk …(8)

[0051] In curves 510, 560, 610, and 660, different control repetitions within the repetition interval DS are not considered. That is, when position Pk is within the repetition interval DS, the control according to the second control quantity Fk shown in equation (8) and the control according to the first control quantity Vk shown in equation (7) are not considered simultaneously. Therefore, it is possible that the accuracy of wire discharge machining in the repetition interval DS will decrease. In addition, it is possible that the wire electrode 14 will break during wire discharge machining in the repetition interval DS. The reason for this is that the discharge energy in the repetition interval DS becomes unstable due to variations.

[0052] To prevent the aforementioned problems, in this embodiment, the first control quantity V and the second control quantity F are adjusted considering the different control repetitions in the repetition interval DS. The adjustment unit 320 adjusts the first control quantity V and the second control quantity F respectively in the repetition interval DS where the first control quantity V and the second control quantity F change repeatedly.

[0053] The adjustment unit 320 adjusts the first control quantity V in the repetition interval DS according to the first ratio RVk and the second ratio RFk. Specifically, the adjustment unit 320 calculates the first adjustment ratio RVAk using equation (9). The first adjustment ratio RVAk is used to adjust the first control quantity V. As shown in equation (9), the first adjustment ratio RVAk is obtained as the ratio of the first ratio RVk to the sum of the first ratio RVk and the second ratio RFk.

[0054] RVAk=RVk / (RVk+RFk)…(9)

[0055] The adjustment unit 320 adjusts the second control quantity F in the repetition interval DS according to the first ratio RVk and the second ratio RFk. Specifically, the adjustment unit 320 calculates the second adjustment ratio RFAk using equation (10). As shown in equation (10), the second adjustment ratio RFAk is obtained as the ratio of the second ratio RFk to the sum of the first ratio RVk and the second ratio RFk. Furthermore, as can be seen from equations (9) and (10), the sum of the first adjustment ratio RVAk and the second adjustment ratio RFAk is 1. Figure 4 As shown, when the first adjustment ratio RVAk and the second adjustment ratio RFAk are displayed as percentage values, their sum is 100%.

[0056] RFAk=RFk / (RVk+RFk)…(10)

[0057] The change of the first adjustment ratio RVAk corresponding to the position on the machining path RT is shown in curve 710. The change of the second adjustment ratio RFAk corresponding to the position on the machining path RT is shown in curve 760. In the repeat interval DS, the first adjustment ratio RVAk and the second adjustment ratio RFAk are calculated at each position Pk. In the repeat interval DS, the adjustment unit 320 adjusts the first control quantity Vk and the second control quantity Fk at each position Pk based on the first adjustment ratio RVAk and the second adjustment ratio RFAk.

[0058] Equations (11) and (12) are used to calculate the adjusted first control quantity VAk and the adjusted second control quantity FAk in the repetition interval DS, respectively. As shown in Equation (11), the adjusted first control quantity VAk is obtained by multiplying the first adjustment ratio RVAk by the maximum change ΔVmax of the first control quantity V and adding the reference control quantity V0. As shown in Equation (12), the adjusted second control quantity FAk is obtained by multiplying the second adjustment ratio RFAk by the maximum change ΔFmax of the second control quantity F and adding the reference control quantity F0.

[0059] VAk=V0+ΔVmax×RVAk…(11)

[0060] FAk=F0+ΔFmax×RFAk…(12)

[0061] In the repetitive interval DS, the machining control unit 310 controls the machining power supply 28 of the wire electrical discharge machine 10 according to the adjusted first control quantity VAk and the adjusted second control quantity FAk, based on equations (11) and (12). Compared with machining control based on equations (7) and (8) according to the first control quantity Vk and the second control quantity Fk, the accuracy of wire electrical discharge machining in the repetitive interval DS is improved. In addition, the possibility of wire electrode 14 breaking is reduced in wire electrical discharge machining in the repetitive interval DS.

[0062] Figure 5 This is a flowchart illustrating the control process of the wire electrical discharge machining (EDM) machine 10 performed by the control device 30 in this embodiment. When this control process begins, in step S510, the machining control unit 310 sets a reference control quantity V0 for the first control quantity V and a reference control quantity F0 for the second control quantity F. The machining control unit 310 controls the EDM machine 10 to perform EDM based on the reference control quantity V0 and the reference control quantity F0, which are based on reference machining conditions. Thus, the machining control unit 310 performs machining control of a straight path interval starting from the machining start position on the machining path RT.

[0063] In step S512, the machining control unit 310 determines whether to start machining of the inner corner interval CI, starting from position PA on the machining path RT. When the wire electrode 14 moves relative to the workpiece W from the machining start position and reaches position PA, the result in step S512 is "Yes", and the control process proceeds to step S514. If the wire electrode 14 has not yet reached position PA, the result in step S512 is "No", and the control process returns to step S510.

[0064] In step S514, the machining control unit 310 changes the first control quantity V to the inner corner interval CI for machining control. The machining control unit 310 gradually increases the first control quantity V until it reaches the maximum control quantity VH based on the machining conditions used for the inner corner interval CI. The machining control unit 310 controls the electrical discharge machining of the wire electrical discharge machine 10 according to the gradually increasing first control quantity V. Furthermore, when the first control quantity V reaches the maximum control quantity VH, the subsequent first control quantity V remains at the maximum control quantity VH. In this way, the machining control unit 310 performs machining control from position PA to the inner corner interval CI.

[0065] In step S516, the machining control unit 310 determines whether to begin machining of the outer corner interval CO, starting from position PB on the machining path RT. When the wire electrode 14 moves from position PA relative to the workpiece W and reaches position PB, the result in step S516 is "Yes," and the control process proceeds to step S518. If the wire electrode 14 has not yet reached position PB, the result in step S516 is "No," and the control process returns to step S514.

[0066] Furthermore, in the repeating interval DS from position PB to position PD within the outer corner interval CO, machining control based on a first control amount V exceeding the reference control amount V0 is repeated with machining control based on a second control amount F exceeding the reference control amount F0. When "Yes" is selected in step S516, the machining control unit 310 determines to start machining in the repeating interval DS within the outer corner interval CO.

[0067] In step S518, the adjustment unit 320 calculates the first ratio RVk and the second ratio RFk using equations (1) to (6).

[0068] In step S520, the adjustment unit 320 uses equations (9) and (10) to calculate the first adjustment ratio RVAk and the second adjustment ratio RFAk.

[0069] In step S522, the adjustment unit 320 adjusts the first control quantity Vk and the second control quantity Fk, which change repeatedly according to the processing conditions used in the outer corner interval CO, based on the first adjustment ratio RVAk and the second adjustment ratio RFAk. The adjustment unit 320 calculates the adjusted first control quantity VAk and the adjusted second control quantity FAk in the repeating interval DS using equations (11) and (12).

[0070] In step S524, the machining control unit 310 controls the electrical discharge machining of the line electrical discharge machine 10 in the repeat interval DS according to the adjusted first control quantity VAk and the adjusted second control quantity FAk.

[0071] In step S526, the machining control unit 310 determines whether the first control quantity V has changed to the reference control quantity V0. When the first control quantity V changes to become the reference control quantity V0, the result in "Yes" in step S526, and the control process proceeds to step S528. The position of the wire electrode 14 when the first control quantity V changes to reach the reference control quantity V0 is set as position PD. When the wire electrode 14 reaches position PD, the machining of the repeat interval DS ends. If the first control quantity V has not yet reached the reference control quantity V0, the result in "No" in step S526, and the control process returns to step S518. The wire electrode 14 has not yet reached position PD and is still moving relative to the reference control quantity V0 within the repeat interval DS.

[0072] The section located at the front end of the repeating interval DS, from position PD to position PC, is part of the outer corner interval CO. In step S528, the machining control unit 310 controls the electrical discharge machining of the line electrical discharge machine 10 according to the machining conditions used for the outer corner interval CO, and according to the second control quantity F that increases or maintains the maximum control quantity FH.

[0073] In step S530, the machining control unit 310 determines whether machining of the outer corner interval CO has ended. If the wire electrode 14 has moved from position PD relative to the workpiece W and reached position PC, then "yes" is indicated in step S530, and the control process proceeds to step S532. If the wire electrode 14 has not yet reached position PC, then "no" is indicated in step S530, and the control process returns to step S528.

[0074] In step S532, the machining control unit 310 gradually decreases the second control quantity F according to the machining conditions for the section of the straight path. The machining control unit 310 controls the electrical discharge machining of the wire electrical discharge machine 10 according to the gradually decreasing second control quantity F. Furthermore, when the second control quantity F reaches the reference control quantity F0, subsequent second control quantities F remain at the reference control quantity F0. In this way, the machining control unit 310 performs machining control for the section of the straight path preceding the position PC on the machining path RT.

[0075] In step S534, the machining control unit 310 determines whether machining of the section of the straight path preceding position PC has ended. If the wire electrode 14 has moved relative to the workpiece W and reached the machining end position on the machining path RT, then step S534 is "Yes", and this control process ends. If the wire electrode 14 has not yet reached the machining end position, then step S534 is "No", and this control process returns to step S532.

[0076] [Variation Example]

[0077] The above-described embodiments can also be modified as follows.

[0078] (Variation Example 1)

[0079] In the above embodiment, the adjustment unit 320 uses formulas (9) and (10) to calculate the first adjustment ratio RVAk and the second adjustment ratio RFAk. Figure 5 (Step S520). Alternatively, at least one of the first ratio RVk and the second ratio RFk used in these calculations can be assigned a weighting factor greater than 1. The control quantity corresponding to the ratio assigned a larger weighting factor has a greater impact on the processing control in the repetition interval DS.

[0080] For example, when a weighting coefficient α greater than 1 is assigned to the second ratio RFk, the adjustment unit 320 calculates the first adjustment ratio RVAk and the second adjustment ratio RFAk using equations (13) and (14). The second control quantity F has a greater influence on the processing control in the repetitive interval DS than the first control quantity V.

[0081] RVAk=RVk / (RVk+α×RFk)…(13)

[0082] RFAk=α×RFk / (RVk+α×RFk)…(14)

[0083] Figure 6 This is a flowchart illustrating the control process of the wire electrical discharge machine 10 performed by the control device 30 in Modified Example 1. Except for step S620, it assigns... Figure 6 The symbols and assignments for each step of the control process are shown. Figure 5 The symbols for each step of the control process shown are consistent, indicating that the same process is performed. Therefore, the symbols for each step are omitted. Figure 6 The processing of steps S510 to S518 and steps S522 to S534 will be explained, but only the processing of step S620 will be explained.

[0084] When the processing in step S518 ends, this control process proceeds to step S620. In step S620, the adjustment unit 320 calculates the first adjustment ratio RVAk and the second adjustment ratio RFAk based on the weighting coefficient α using equations (13) and (14). When the processing in step S620 ends, this control process proceeds to step S522.

[0085] (Variation Example 2)

[0086] In the above embodiments, the first control quantity is a pulse voltage control quantity, and the second control quantity is a pulse number control quantity, but is not limited to these control quantities. For example, the first control quantity can be a machining speed control quantity. The second control quantity can also be a machining fluid control quantity.

[0087] (Variation Example 3)

[0088] At least one of the first and second control quantities can be multiple control quantities. For example, in the inner corner interval CI, the pulse voltage control quantity may increase, and the machining speed control quantity may also increase. In the outer corner interval CO immediately following the inner corner interval CI, the machining fluid control quantity may also increase together with the pulse number control quantity. In this case, the first control quantity that the machining control unit 310 changes based on the machining conditions used in the inner corner interval CI is the pulse voltage control quantity and the machining speed control quantity. The second control quantity that the machining control unit 310 changes based on the machining conditions used in the outer corner interval CO is the pulse number control quantity and the machining fluid control quantity.

[0089] (Variation Example 4)

[0090] In the above embodiments and variations, in the corner path on the processing path RT, the inner corner interval CI is followed by the outer corner interval CO. Alternatively, the outer corner interval CO may be followed by the inner corner interval CI. In this case, the repeating interval is contained within the inner corner interval CI. The starting point of the repeating interval coincides with the starting point of the inner corner interval CI located after the outer corner interval CO.

[0091] (Variation Example 5)

[0092] The above-described embodiments and variations can be combined arbitrarily.

[0093] [Invention derived from implementation methods]

[0094] The invention described below can be understood from the above embodiments and variations.

[0095] (1) A control device (30) for a wire electrical discharge machining (10) that moves a wire electrode (14) relative to a workpiece (W) along a machining path (RT) while generating a discharge between the wire electrode and the workpiece (G) to machine the workpiece, the control device comprising: a machining control unit (310) that controls the wire electrical discharge machining according to a plurality of control quantities based on reference machining conditions, and in an inner corner interval (CI), controlling the wire electrical discharge machining by changing at least one first control quantity (V) of the plurality of control quantities based on machining conditions for the inner corner interval, and in an outer corner interval (CO) immediately following the inner corner interval, controlling the wire electrical discharge machining by changing at least one second control quantity of the plurality of control quantities that is different from the first control quantity based on machining conditions for the outer corner interval. The machining control unit (320) controls the wire electrical discharge machining (EDM) by varying the quantity (F). It also calculates, within a repeating interval (DS) where the first and second control quantities repeatedly change, a first ratio (RVk) is calculated based on the ratio of the current change (ΔVk) of the first control quantity to the maximum change (ΔVmax) of the first control quantity, and a second ratio (RFk) is calculated based on the ratio of the current change (ΔFk) of the second control quantity to the maximum change (ΔFmax) of the second control quantity. The current first and second control quantities are adjusted based on the first and second ratios, respectively. Within the repeating interval where the first and second control quantities repeatedly change, the machining control unit controls the EDM according to the adjusted first and second control quantities. This improves the accuracy of EDM in repeating intervals where corner intervals are continuous. Furthermore, the possibility of wire electrode breakage during EDM in repeating intervals is reduced.

[0096] (2) The adjustment unit calculates a first adjustment ratio (RVAk) and a second adjustment ratio (RFAk) based on the first ratio and the second ratio, adjusts the current first control quantity based on the first adjustment ratio, and adjusts the current second control quantity based on the second adjustment ratio. This improves the accuracy of wire discharge machining in repetitive intervals when corner intervals are continuous. Furthermore, the possibility of wire electrode breakage during wire discharge machining in repetitive intervals is reduced.

[0097] (3) The sum of the first adjustment ratio and the second adjustment ratio is 100%. This improves the accuracy of wire discharge machining in repeating intervals when the corner intervals are continuous. In addition, the possibility of wire electrode breakage during wire discharge machining in repeating intervals is reduced.

[0098] (4) The adjustment unit calculates the first adjustment ratio and the second adjustment ratio based on the first ratio, the second ratio, and a predetermined weighting coefficient (α) assigned to at least one of the first ratio and the second ratio. Therefore, the control quantity corresponding to the ratio with the larger weighting coefficient among the first and second ratios can increase the influence on the processing control of the repetitive interval compared to the control quantity corresponding to the ratio with the assigned weighting coefficient. Furthermore, it is easy to fine-tune the degree of change in the control quantity corresponding to the ratio with the assigned weighting coefficient.

[0099] (5) The first control quantity and the second control quantity each include at least one of the following control quantities: a control quantity for controlling the speed at which the wire electrical discharge machine processes the workpiece; a control quantity for controlling the magnitude of the pulse voltage applied to the electrode space when the wire electrical discharge machine generates the discharge; a control quantity for controlling the number of pulses per unit time of the pulse voltage applied to the electrode space when the wire electrical discharge machine generates the discharge; and a control quantity for controlling the flow rate per unit time of the processing fluid supplied to the electrode space when the wire electrical discharge machine generates the discharge. Therefore, the accuracy of wire electrical discharge machining in repeating intervals when corner intervals are continuous is further improved. Furthermore, the possibility of wire electrode breakage during wire electrical discharge machining in repeating intervals is further reduced.

[0100] (6) A control method for a wire electrical discharge machining (10) wherein a wire electrode (14) moves relative to a workpiece (W) along a machining path (RT), and simultaneously discharges between the wire electrode and the workpiece (G) to machine the workpiece. In this control method, the machining control is performed as follows: the wire electrical discharge machining is controlled according to a plurality of control quantities based on reference machining conditions; and in an inner corner interval (CI), the wire electrical discharge machining is controlled by changing at least one first control quantity (V) of the plurality of control quantities based on the machining conditions for the inner corner interval; and in an outer corner interval (CO) immediately following the inner corner interval, at least one second control quantity (F) of the plurality of control quantities, different from the first control quantity, is changed based on the machining conditions for the outer corner interval. To control the wire electrical discharge machining (EDM) machine, the following adjustments are made: In the repetitive interval (DS) where the first and second control quantities repeatedly change, the ratio of the current change (ΔVk) of the first control quantity to its maximum change (ΔVmax), i.e., the first ratio (RVk), and the ratio of the current change (ΔFk) of the second control quantity to its maximum change (ΔFmax), i.e., the second ratio (RFk), are calculated. Based on the first ratio and the second ratio, the current first and second control quantities are adjusted respectively. During machining control, in the repetitive interval where the first and second control quantities repeatedly change, the wire EDM machine is controlled according to the adjusted first and second control quantities. This improves the accuracy of wire EDM in repetitive intervals with continuous corner intervals. Furthermore, the possibility of wire electrode breakage during wire EDM in repetitive intervals is reduced.

[0101] (7) When making the adjustment, a first adjustment ratio (RVAk) and a second adjustment ratio (RFAk) are calculated based on the first ratio and the second ratio. The current first control quantity is adjusted based on the first adjustment ratio, and the current second control quantity is adjusted based on the second adjustment ratio. This improves the accuracy of wire discharge machining in repetitive intervals when corner intervals are continuous. Furthermore, the possibility of wire electrode breakage during wire discharge machining in repetitive intervals is reduced.

[0102] (8) The sum of the first adjustment ratio and the second adjustment ratio is 100%. This improves the accuracy of wire discharge machining in repeating intervals when the corner interval is continuous. In addition, the possibility of wire electrode breakage during wire discharge machining in repeating intervals is reduced.

[0103] (9) When making the adjustment, the first adjustment ratio and the second adjustment ratio are calculated based on the first ratio, the second ratio, and a predetermined weighting coefficient (α) assigned to at least one of the first ratio and the second ratio. Therefore, the control quantity corresponding to the ratio with the larger weighting coefficient among the first and second ratios can increase the influence on the processing control of the repetitive interval compared to the control quantity corresponding to the ratio with the assigned weighting coefficient. Furthermore, it is easy to fine-tune the degree of change in the control quantity corresponding to the ratio with the assigned weighting coefficient.

[0104] (10) The first control quantity and the second control quantity each include at least one of the following control quantities: a control quantity for controlling the speed at which the wire electrical discharge machine processes the workpiece; a control quantity for controlling the magnitude of the pulse voltage applied to the electrode space when the wire electrical discharge machine generates the discharge; a control quantity for controlling the number of pulses per unit time of the pulse voltage applied to the electrode space when the wire electrical discharge machine generates the discharge; and a control quantity for controlling the flow rate per unit time of the processing fluid supplied to the electrode space when the wire electrical discharge machine generates the discharge. Therefore, the accuracy of wire electrical discharge machining in repeating intervals when corner intervals are continuous is further improved. Furthermore, the possibility of wire electrode breakage during wire electrical discharge machining in repeating intervals is further reduced.

[0105] Symbol Explanation

[0106] 10… wire EDM machine 12… worktable

[0107] 14…line electrode 16…upper wire guide

[0108] 18…Offline guide component 20…Upline guide block

[0109] 22…lower guide block 24…winding tube

[0110] 26…Recycling bin 28…Processing power supply

[0111] 30…Control device 32…Output drive unit

[0112] 34…processing groove 36…roller

[0113] 38…base 40…displacement drive unit

[0114] 44…pinch rollers 46…feed rollers

[0115] 48…Pump 310…Machining Control Department

[0116] 320… Adjustment section 510, 560, 610, 660, 710, 760… curves.

Claims

1. A control device (30) for a wire electrical discharge machining (10), the wire electrical discharge machining (10) moving a wire electrode (14) relative to a workpiece (W) along a machining path (RT) while simultaneously generating a discharge (G) between the wire electrode and the workpiece to machine the workpiece, the control device for the wire electrical discharge machining is characterized by comprising: A machining control unit (310) controls the wire electrical discharge machine according to a plurality of control quantities based on reference machining conditions. In the inner corner interval (CI), based on the machining conditions for the inner corner interval, it controls the wire electrical discharge machine by changing at least one first control quantity (V) among the plurality of control quantities. In the outer corner interval (CO) immediately following the inner corner interval, based on the machining conditions for the outer corner interval, it controls the wire electrical discharge machine by changing at least one second control quantity (F) among the plurality of control quantities that is different from the first control quantity. The adjustment unit (320) calculates, within the repetition interval (DS) where the first control quantity and the second control quantity repeatedly change, a first ratio (RVk) relative to the maximum change of the first control quantity (ΔVk) and a second ratio (RFk) relative to the maximum change of the second control quantity (ΔFk) and the second ratio, respectively, the ratio of the current change of the first control quantity (ΔVk) to the maximum change of the second control quantity (ΔFmax) during the repetition interval (DS ... During the repetition interval in which the first control quantity and the second control quantity are repeatedly varied, the machining control unit controls the wire electrical discharge machine according to the adjusted first control quantity and the adjusted second control quantity.

2. The control device for a wire electrical discharge machining machine according to claim 1, characterized in that, The adjustment unit calculates a first adjustment ratio (RVAk) and a second adjustment ratio (RFAk) based on the first ratio and the second ratio, adjusts the current first control quantity based on the first adjustment ratio, and adjusts the current second control quantity based on the second adjustment ratio.

3. The control device for a wire electrical discharge machining machine according to claim 2, characterized in that, The sum of the first adjustment ratio and the second adjustment ratio is 100%.

4. The control device for a wire electrical discharge machining machine according to claim 2 or 3, characterized in that, The adjustment unit calculates the first adjustment ratio and the second adjustment ratio based on the first ratio, the second ratio, and a predetermined weighting coefficient (α) assigned to at least one of the first ratio and the second ratio.

5. The control device for a wire electrical discharge machining machine according to any one of claims 1 to 3, characterized in that, The first control quantity and the second control quantity each include at least one of the following control quantities: a control quantity for controlling the speed at which the wire electrical discharge machine processes the workpiece; a control quantity for controlling the magnitude of the pulse voltage applied to the electrode space when the wire electrical discharge machine generates the discharge; a control quantity for controlling the number of pulses per unit time of the pulse voltage applied to the electrode space when the wire electrical discharge machine generates the discharge; and a control quantity for controlling the flow rate per unit time of the processing fluid supplied to the electrode space when the wire electrical discharge machine generates the discharge.

6. A control method for a wire electrical discharge machining (10) wherein the wire electrical discharge machining (10) moves a wire electrode (14) relative to a workpiece (W) along a machining path (RT), and simultaneously generates a discharge (G) between the wire electrode and the workpiece to machine the workpiece, wherein the control method for the wire electrical discharge machining is characterized in that… The machining control is performed as follows: the wire electrical discharge machine is controlled according to multiple control quantities based on reference machining conditions; and in the inner corner interval (CI), the wire electrical discharge machine is controlled by changing at least one first control quantity (V) among the multiple control quantities based on the machining conditions used for the inner corner interval; and in the outer corner interval (CO) immediately following the inner corner interval, the wire electrical discharge machine is controlled by changing at least one second control quantity (F) among the multiple control quantities that is different from the first control quantity based on the machining conditions used for the outer corner interval. The following adjustments are made: Within the repetition interval (DS) where the first control quantity and the second control quantity repeatedly change, the ratio of the current change (ΔVk) of the first control quantity to the maximum change (ΔVmax) of the first control quantity, i.e., the first ratio (RVk), and the ratio of the current change (ΔFk) of the second control quantity to the maximum change (ΔFmax) of the second control quantity, i.e., the second ratio (RFk), are calculated. Based on the first ratio and the second ratio, the current first control quantity and the current second control quantity are adjusted respectively. During the machining control, the wire electrical discharge machine is controlled according to the adjusted first control quantity and the adjusted second control quantity during the repetition interval in which the first control quantity and the second control quantity are repeatedly changed.

7. The control method for a wire electrical discharge machining machine according to claim 6, characterized in that, When making the adjustment, a first adjustment ratio (RVAk) and a second adjustment ratio (RFAk) are calculated based on the first ratio and the second ratio. The current first control quantity is adjusted based on the first adjustment ratio, and the current second control quantity is adjusted based on the second adjustment ratio.

8. The control method for a wire electrical discharge machining machine according to claim 7, characterized in that, The sum of the first adjustment ratio and the second adjustment ratio is 100%.

9. The control method for a wire electrical discharge machining machine according to claim 7 or 8, characterized in that, When making the adjustment, the first adjustment ratio and the second adjustment ratio are calculated based on the first ratio, the second ratio, and a prescribed weighting coefficient (α) assigned to at least one of the first ratio and the second ratio.

10. The control method for a wire electrical discharge machining machine according to any one of claims 6 to 8, characterized in that, The first control quantity and the second control quantity each include at least one of the following control quantities: a control quantity for controlling the speed at which the wire electrical discharge machine processes the workpiece; a control quantity for controlling the magnitude of the pulse voltage applied to the electrode space when the wire electrical discharge machine generates the discharge; a control quantity for controlling the number of pulses per unit time of the pulse voltage applied to the electrode space when the wire electrical discharge machine generates the discharge; and a control quantity for controlling the flow rate per unit time of the processing fluid supplied to the electrode space when the wire electrical discharge machine generates the discharge.

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