Wire discharge machining device and wire discharge machining method

Abstract

The control unit (300) drives the cutting feed table (10) when the cutting process begins, so that the workpiece fixing plate and the pair of processing fluid rectifier plates (41) that fix the workpiece (W) approach the multiple cutting line sections (1b) and move upward relative to the pair of processing fluid discharge prevention plates (43). The control unit controls the holding device in such a way that the workpiece pressing part (46) is held in the initial cutting position by moving upward until the workpiece (W) reaches the first position. The control unit controls the holding device in such a way that the holding of the workpiece pressing part (46) is released after the workpiece (W) reaches the first position.

Description

Technical Field

[0001] This invention relates to a wire electrical discharge machining apparatus and a wire electrical discharge machining method for performing electrical discharge machining that cuts multiple plate-shaped parts from a workpiece using a wire electrode. Background Technology

[0002] In multi-wire electrical discharge machining (EDM) apparatuses, discharge occurs between multiple wire electrodes and the workpiece, cutting multiple plate-shaped components from the workpiece simultaneously. EDM apparatuses are used, for example, in semiconductor manufacturing processes, in the dicing process of cutting multiple wafers from an ingot. During the formation of the plates being processed together, the flow of the processing fluid supplied between the electrodes oscillates, causing narrowing between adjacent plates. As a result, the EDM process becomes unstable due to poor chip removal or inadequate cooling of the wire electrodes.

[0003] In Patent Document 1, a pressing plate is provided to support the workpiece by pressing it down from above, thereby suppressing the floating of the wafer caused by vibrations of the workpiece due to wire travel and external forces during cutting. The force applied to the pressing plate is obtained using a counterweight or a drive device such as an electric motor.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2002-205255 Summary of the Invention

[0005] In Patent Document 1, the weight of the counterweight becomes the load on the platform on which the workpiece is placed. When multiple workpieces are placed on the same platform for processing, the weight of the counterweight increases, requiring reinforcement of the platform mechanism, such as preventing deformation of the worktable and increasing the driving force. Furthermore, in Patent Document 1, the workpiece is pressed by a pressing plate from the start to the end of processing. Therefore, in the method using a drive device such as an electric motor, in order to prevent interference between the wire electrode and the pressing plate, a load needs to be applied to the workpiece by the pressing plate, and the pressing plate needs to be moved and driven from the start to the end of processing, which complicates control.

[0006] The present invention was made in view of the above circumstances, and its purpose is to obtain a wire discharge machining apparatus that does not require the reinforcement of a platform mechanism and achieves wire discharge machining under simple control.

[0007] To solve the aforementioned problems and achieve the objective, the wire electrical discharge machining apparatus of the present invention includes a wire electrode, a power supply unit, a pair of nozzles, a workpiece fixing plate, a pair of machining fluid rectifier plates, a pair of machining fluid discharge prevention plates, a workpiece pressing unit, a cutting feed stage, a holding device, and a control unit. The wire electrode has cutting wire portions that are separated from each other and face the workpiece. The power supply unit generates discharge between the multiple cutting wire portions and the workpiece. The pair of nozzles has multiple ejection holes through which the multiple cutting wire portions are inserted, supplying machining fluid to the gap between the multiple cutting wire portions and the workpiece. The workpiece fixing plate holds and fixes the workpiece. The pair of machining fluid rectifier plates are disposed on both sides of the workpiece in a manner that clamps the workpiece. The pair of machining fluid discharge prevention plates are disposed in a manner that clamps the workpiece fixing plate and the pair of machining fluid rectifier plates, and have multiple through holes connected to the multiple ejection holes of the pair of nozzles and through which the multiple cutting wire portions are inserted. The workpiece pressing part is inserted above the workpiece and multiple cutting lines into the space surrounded by a pair of processing fluid rectifier plates and a pair of processing fluid discharge prevention plates, holding the workpiece separated during cutting. The cutting feed table moves the workpiece fixing plate and the pair of processing fluid rectifier plates relative to the pair of processing fluid discharge prevention plates and multiple cutting lines vertically. The holding device holds the workpiece pressing part in the initial cutting position, separating it upwards from the cutting lines. The control unit drives the cutting feed table when cutting begins, moving the workpiece fixing plate and the pair of processing fluid rectifier plates, which hold the workpiece, closer to the multiple cutting lines, and moves them upwards relative to the pair of processing fluid discharge prevention plates. The holding device is controlled to hold the workpiece pressing part in the initial cutting position by moving upwards until the workpiece reaches the first position, and the holding device is released after the workpiece reaches the first position.

[0008] The effects of the invention

[0009] The wire electrical discharge machining apparatus according to the present invention has the effect of not requiring the reinforcement of the platform mechanism and achieving wire electrical discharge machining under simple control. Attached Figure Description

[0010] Figure 1 This is a conceptual diagram illustrating a structural example of the wire electrical discharge machining apparatus according to Embodiment 1.

[0011] Figure 2 This is an exploded perspective view showing a structural example of the machining fluid flow path restriction section of the wire electrical discharge machining apparatus according to Embodiment 1.

[0012] Figure 3 This is a perspective view showing the structure of the workpiece pressing part of the wire electrical discharge machining apparatus according to Embodiment 1.

[0013] Figure 4 This is a cross-sectional view showing the structure of the machining fluid flow path restriction part of the wire electrical discharge machining apparatus according to Embodiment 1.

[0014] Figure 5 This is another cross-sectional view showing the structure of the machining fluid flow path restriction part of the wire electrical discharge machining apparatus according to Embodiment 1.

[0015] Figure 6 This is a block diagram illustrating a structural example of the control unit of the wire electrical discharge machining apparatus according to Embodiment 1.

[0016] Figure 7 This is a flowchart illustrating the cutting operation of the wire electrical discharge machining apparatus according to Embodiment 1.

[0017] Figure 8 This is a cross-sectional view showing the first stage of the cutting process of the wire electrical discharge machining apparatus according to Embodiment 1.

[0018] Figure 9 This is a cross-sectional view showing the second stage of the cutting process of the wire electrical discharge machining apparatus according to Embodiment 1.

[0019] Figure 10 This is a cross-sectional view showing the third stage of the cutting process of the wire electrical discharge machining apparatus according to Embodiment 1.

[0020] Figure 11 This is an exploded perspective view showing a structural example of the machining fluid flow path restriction section of the wire electrical discharge machining apparatus according to Embodiment 2.

[0021] Figure 12 This is a block diagram illustrating an example of the hardware structure of the control unit of the wire electrical discharge machining apparatus according to embodiments 1 and 2. Detailed Implementation

[0022] The wire discharge machining apparatus and wire discharge machining method according to the embodiments will now be described in detail based on the accompanying drawings.

[0023] Implementation method 1.

[0024] Figure 1 This is a conceptual diagram illustrating a structural example of the wire electrical discharge machining apparatus 1000 according to Embodiment 1. Figure 1 The x-axis, y-axis, and z-axis of a 3-axis orthogonal coordinate system are shown. The y-axis corresponds to the travel direction of the wire electrode 1 on the workpiece W, the z-axis corresponds to the height direction (vertical direction), and the x-axis corresponds to the direction in which multiple wire electrodes 1 are arranged side by side on the workpiece W.

[0025] The wire electrical discharge machining (EDM) apparatus 1000 includes: a machining mechanism 100 that cuts a workpiece W using a wire electrode 1; a power supply 200 that supplies power; a control unit 300; and a machining fluid flow path restriction unit 400. The EDM apparatus 1000 cuts out multiple plate-shaped components from the workpiece W simultaneously. Examples of the workpiece W include tungsten, molybdenum, silicon carbide, monocrystalline silicon, monocrystalline silicon carbide, gallium nitride, and polycrystalline silicon.

[0026] The processing mechanism 100 includes multiple guide rollers 2, spools 3, vibration damping guide rollers 4a and 4b, and nozzles 7a and 7b (see reference). Figure 2 The system includes 8a and 8b for spool rotation control, 9a and 9b for traverse control, and a cutting feed table 10. Multiple guide rollers 2 consist of guide roller 2-1, guide roller 2-2, guide roller 2-3, and guide roller 2-4. The spool 3 consists of spool 3-1 and spool 3-2.

[0027] Multiple guide rollers 2 guide the movement of the wire electrode 1. Guide rollers 2-1, 2-2, 2-3, and 2-4 are rotatably arranged about their respective axes of rotation. Guide rollers 2-1, 2-2, 2-3, and 2-4 are arranged separately from each other, with their axes of rotation parallel to each other. The parallel axes of rotation of guide rollers 2-1, 2-2, 2-3, and 2-4 enable the wire electrode 1 to move with high precision. The axes of rotation of guide rollers 2-1, 2-2, 2-3, and 2-4 are parallel to the x-axis.

[0028] A single wire electrode 1 is wound multiple times around guide rollers 2-1, 2-2, 2-3, and 2-4 at intervals along the rotation axes of each roller. These wire electrodes 1 are collectively referred to as parallel wire section 1a, and the portion of parallel wire section 1a opposite the workpiece W is referred to as cutting wire section 1b. Cutting wire section 1b is composed of multiple parallel wire electrodes 1. Preferably, the cutting wire sections 1b are arranged parallel to each other. Multiple guide grooves are formed at equal intervals on the surfaces of guide rollers 2-1, 2-2, 2-3, and 2-4. The wire electrodes 1 are wound along these guide grooves, thereby maintaining a constant interval between the wire electrodes 1 by the guide rollers 2-1, 2-2, 2-3, and 2-4. If the cutting wire sections 1b are arranged parallel to each other and at equal intervals, the thickness of the multiple cut plate-shaped parts is equal, and the cross-sections can be made parallel. In addition, the number of guide rollers 2 does not necessarily have to be 4; it can be less than or equal to 3 or greater than or equal to 5.

[0029] The bobbins 3-1 and 3-2 move the wire electrode 1 by pulling out and winding. Bobbin 3-1 is pulled out, and bobbin 3-2 is wound. The bobbin rotation control device 8a and the traverse control device 9a control bobbin 3-1. The bobbin rotation control device 8b and the traverse control device 9b control bobbin 3-2. The bobbin rotation control devices 8a and 8b control the rotation of bobbins 3-1 and 3-2 respectively, and thus control the movement of the wire electrode 1. For example, the bobbin rotation control devices 8a and 8b control the direction and speed of movement of the wire electrode 1.

[0030] The traverse control device 9a controls the x-axis position of the bobbin 3-1 in accordance with the withdrawal position of the wire electrode 1. The traverse control device 9b controls the x-axis position of the bobbin 3-2 in accordance with the winding position of the wire electrode 1. The position control of the bobbins 3-1 and 3-2 by the traverse control devices 9a and 9b is called traverse control. Through traverse control, the bobbins 3-1 and 3-2 can stably and accurately move the wire electrode 1.

[0031] The wire electrode 1, drawn from the spool 3-1, is sequentially wound onto guide rollers 2-2, 2-1, 2-4, and 2-3, and then wound again starting from guide roller 2-2. As described above, the wire electrode 1 rotates multiple times between guide rollers 2-1, 2-2, 2-3, and 2-4, and then winds back onto the spool 3-2.

[0032] The workpiece W is fixed inside the machining fluid flow path restriction section 400. The machining fluid flow path restriction section 400 will be described in detail later. The machining fluid flow path restriction section 400, in which the workpiece W is fixed inside, is provided between vibration damping guide rollers 4a and 4b. The vibration damping guide rollers 4a and 4b restrict the movement of the wire electrode 1 in the z-axis direction, thereby suppressing the vibration of the wire electrode 1 in the wire cutting section 1b. Furthermore, the portion of the parallel wire section 1a opposite to the workpiece W is referred to as the wire cutting section 1b, but the portion between the vibration damping guide rollers 4a and 4b in the parallel wire section 1a is also called the wire cutting section 1b. Alternatively, the vibration damping guide rollers 4a and 4b can be omitted.

[0033] Nozzle 7a is positioned between vibration damping guide roller 4a and processing fluid flow path restriction part 400 (see reference). Figure 2 Nozzle 7b is positioned between vibration damping guide roller 4b and processing fluid flow path restriction section 400. Processing fluid is filled inside nozzles 7a and 7b. Nozzles 7a and 7b have multiple ejection holes (not shown) that spray the processing fluid filled inside towards the workpiece W within the processing fluid flow path restriction section 400. Cutting wire section 1b is inserted through the multiple ejection holes of nozzles 7a and 7b.

[0034] The cutting feed stage 10 changes the relative position between the workpiece W and the cutting line portion 1b. In Embodiment 1, the position of the cutting line portion 1b in the z-axis direction is fixed, while the cutting feed stage 10 is movable in the z-axis direction. Details will be provided later. The cutting feed stage 10 causes the structural elements inside the machining fluid flow path restriction portion 400 to move up and down relative to a pair of machining fluid discharge prevention plates 43 along with the workpiece W. By moving the cutting feed stage 10 up and down, the workpiece W is brought closer to or separated from the cutting line portion 1b, thus cutting the workpiece W. Furthermore, by electrical discharge machining on the workpiece W, a machining groove Wz (see reference) is formed on the workpiece W along the cutting line portion 1b. Figure 5 Alternatively, the cutting feed stage 10 can be configured to move in the x-axis, y-axis, and z-axis directions.

[0035] The processing mechanism 100 may include a guide pulley for suppressing vibration of the wire electrode 1, a force measuring element for measuring the tension of the wire electrode 1, and a tension adjusting roller for controlling the tension of the wire electrode 1. The tension of the wire electrode 1 can be maintained within a range suitable for the travel of the wire electrode 1 by means of the force measuring element and the tension adjusting roller. For example, the tension adjusting roller can change the extraction speed and winding speed of the wire electrode 1, thereby controlling the tension of the wire electrode 1.

[0036] The power supply unit 200 includes a processing power supply 5 and power supply units 6a and 6b. The processing power supply 5 supplies power to the wire electrode 1 via the power supply units 6a and 6b.

[0037] Figure 2 This is an exploded perspective view showing a structural example of the machining fluid flow path restriction section 400 of the wire electrical discharge machining apparatus 1000 according to Embodiment 1. The machining fluid flow path restriction section 400 has a pair of machining fluid rectifier plates 41, a pair of machining fluid discharge prevention plates 43, a workpiece pressing section 46, and a workpiece fixing plate 42. The machining fluid discharge prevention plate 43 constitutes a first component for mounting the cutting line section 1b. The machining fluid rectifier plates 41 and the workpiece fixing plate 42 constitute a second component, which fixes the workpiece W and, together with the first component, forms a space for the machining fluid to flow from the first component into the workpiece W. The workpiece pressing section 46 is held at the initial cutting position, separating upwards from the cutting line section 1b, and constitutes a third component for holding the workpiece W, which is inserted into the space and cut during cutting, from above.

[0038] The workpiece W is placed and fixed on the workpiece fixing plate 42. The workpiece W is fixed to the workpiece fixing plate 42 by a clamp (not shown) for fixing the workpiece W placed on the cutting feed table 10. The workpiece W is fixed to the workpiece fixing plate 42 in a state where each end face of the workpiece W is clamped and in contact with a pair of processing fluid rectifier plates 41. The pair of processing fluid rectifier plates 41 are arranged parallel to the travel direction of the cutting line section 1b to rectify the flow of processing fluid.

[0039] In the processing fluid flow path restriction section 400, by cutting off the up and down movement of the feed table 10, the workpiece fixing plate 42 and a pair of processing fluid rectifier plates 41 move up and down relative to a pair of processing fluid discharge prevention plates 43.

[0040] A pair of processing fluid discharge prevention plates 43 are attached to the end faces of the workpiece fixing plate 42 and the pair of processing fluid rectifier plates 41, and are disposed on both sides of the workpiece W sandwiched by the processing fluid rectifier plates 41. The pair of processing fluid discharge prevention plates 43 do not move up and down, but are fixedly disposed.

[0041] The machining fluid discharge prevention plate 43 is connected to the nozzles 7a and 7b. Multiple through holes 43a are formed in the portion of the machining fluid discharge prevention plate 43 that contact the nozzle orifices of 7a and 7b, allowing the parallel-moving cutting line portions 1b to pass through, thus discharging the machining fluid. The multiple nozzle orifices of 7a and 7b and the multiple through holes 43a of the machining fluid discharge prevention plate 43 are of the same size. Figure 2 In the diagram, for convenience, the multiple through holes 43a of the processing fluid drainage prevention plate 43 are shown as cuboid openings. The processing fluid drainage prevention plate 43 is also in contact with the workpiece pressing part 46.

[0042] The workpiece pressing part 46 is held in position in the height direction by the workpiece pressing and holding device 47. When the cutting process begins, the workpiece pressing part 46 is held in the initial cutting position where it separates from the workpiece W and the cutting line part 1b upwards. After the cutting process begins, the workpiece pressing part 46 fixes the sheet being processed from the workpiece W into a sheet shape.

[0043] The workpiece pressing and holding device 47 has an arm-shaped holding mechanism 47a, which supports the workpiece pressing part 46. A fitting part 46a is also formed on the workpiece pressing part 46 that engages with the front end of the holding mechanism 47a (see reference). Figure 8The holding mechanism 47a retracts in the x-axis direction. Furthermore, the workpiece pressing and holding device 47 includes a vertical moving mechanism 47b that moves the holding mechanism 47a vertically. The holding mechanism 47a may include, for example, a cylinder and an electric motor. The workpiece pressing and holding device 47 is positioned on the platform of the wire EDM apparatus 1000, in a location where its relative position to the wire cutting portion 1b remains unchanged.

[0044] Processing fluid is supplied from nozzles 7a and 7b to the workpiece W via the processing fluid discharge prevention plate 43. Preferably, the processing fluid outlet of the processing fluid discharge prevention plate 43 is positioned at a height closest to the portion of the workpiece W that has the maximum cut length, so that the processing fluid can easily enter the gap between the cutting line portion 1b and the workpiece W. Furthermore, when the workpiece W is a cylindrical shape with a cut thickness that varies according to the cutting position, the portion of the workpiece W that has the maximum cut length refers to the portion where the cut thickness is the longest, i.e., the diameter portion.

[0045] A certain voltage is applied between the electrodes of the cutting wire 1b and the workpiece W. If the electrode distance falls within a certain range, a discharge occurs between the electrodes. The high heat generated by this discharge melts the workpiece W, resulting in the simultaneous cutting out of multiple plate-shaped components. During processing, if a processing fluid is supplied to the gap between the workpiece W and the cutting wire 1b, the processing chips generated between them can be discharged out of the gap. These processing chips can cause short circuits between the workpiece W and the cutting wire 1b; therefore, by supplying processing fluid, the frequency of short circuits can be reduced.

[0046] Furthermore, a processing fluid tank and a pump can be connected to nozzles 7a and 7b. Additionally, a processing fluid flow path restriction section 400, to which the workpiece W is fixed, can be provided inside a processing tank storing processing fluid, allowing electrical discharge machining to be performed while the workpiece W is immersed in the processing fluid.

[0047] Figure 3 This is a perspective view showing the structure of the workpiece pressing part 46 of the wire electrical discharge machining apparatus 1000 according to Embodiment 1. Figure 4 This is a cross-sectional view showing the structure of the machining fluid flow path restriction section 400 in the wire electrical discharge machining apparatus 1000 according to Embodiment 1. Figure 5 This is another cross-sectional view showing the structure of the machining fluid flow path restriction section 400 in the wire electrical discharge machining apparatus 1000 according to Embodiment 1. Figure 5 The left image is along Figure 4 A cross-sectional view of the X-ray. Figure 5 The right image is... Figure 5 The left image is a magnified view of a portion of the scene. Figure 4The image shows a state where the cutting process of the cylindrical workpiece W, performed by the cutting line 1b, has progressed to about half its completion.

[0048] like Figure 4 and Figure 5 As shown, the workpiece pressing part 46 is inserted into a rectangular area surrounded by a pair of processing fluid rectifier plates 41 and a pair of processing fluid discharge prevention plates 43. The opposing surfaces of the workpiece pressing part 46 opposite to the rectangular area are shaped to be in contact with each other from the start to the end of processing and to be able to slide, so that the processing fluid will not leak from the contact surfaces with the pair of processing fluid rectifier plates 41 and the pair of processing fluid discharge prevention plates 43.

[0049] like Figure 4 As shown, an elastomer 56, made of rubber or the like, is installed on the portion of the workpiece pressing part 46 that is in contact with the processing fluid discharge prevention plate 43, the portion of the pair of processing fluid rectifier plates 41 that is in contact with the processing fluid discharge prevention plate 43, and the portion of the workpiece fixing plate 42 that is in contact with the processing fluid discharge prevention plate 43. When the processing fluid discharge prevention plate 43 is set before processing begins, it is set in a state where the elastomer 56 is deformed relative to the workpiece pressing part 46, the processing fluid rectifier plates 41, and the workpiece fixing plate 42, thereby making the elastomer 56 a sealing material that seals the gaps. As a result, the processing fluid discharge prevention plate 43 is in contact with the workpiece pressing part 46, the processing fluid rectifier plates 41, and the workpiece fixing plate 42, suppressing the outflow of processing fluid from the gaps between the components constituting the processing fluid flow path restriction part 400. Therefore, the flow path of the machining fluid supplied to the interior of the machining fluid flow path restriction section 400 is further limited to each machining tank formed in the workpiece W. As a result, the flow rate of the machining fluid flowing into each machining tank increases, the cutting wire section 1b is cooled, and machining chips are discharged from the electrode space to the outside of the workpiece W, thus performing stable electrical discharge machining. Alternatively, the elastomer 56 can be provided on the machining fluid discharge prevention plate 43 side.

[0050] Workpiece pressing part 46 Figure 3As shown, the contact portion with the workpiece W is machined to conform to the contour shape of the workpiece W. Ingots used in semiconductor wafers are mostly cylindrical. For example, in the case where the workpiece W is a cylindrical ingot with a diameter of 6 inches, the portion of the workpiece pressing portion 46 that contacts the workpiece W is machined into a partially cut-off arc shape with a diameter of 6 inches. A cutout portion 46b is formed in the arc-shaped portion of the workpiece pressing portion 46, and a processing fluid outlet 51 extending from the lower surface to the upper surface is provided in the cutout portion 46b. To increase the contact area with the workpiece W and firmly fix the workpiece W, the arc shape of the workpiece pressing portion 46 is selected corresponding to the outer peripheral shape of the workpiece W. The dimension of the pressing part 46 of the workpiece in the x-axis direction is set to be greater than or equal to the length of the workpiece W in the x-axis direction, and the dimension of the pressing part 46 of the workpiece in the y-axis direction is set to be longer than the cutting width (diameter) of the workpiece W and the same length as the processing fluid rectifier plate 41.

[0051] like Figures 3-5 As shown, holes 52-1 to 52-4 are formed on the surface of the workpiece pressing part 46 opposite to the processing fluid rectifier plate 41. Holes 52-1 to 52-4 are bottomed cylindrical holes. A plunger 48 is provided in each hole 52-1 to 52-4. The plunger 48 is as follows: Figure 5 As shown, it has a pin 48a and a spring 48b. The pin 48a is forced outward by the spring 48b. On the other hand, a recess 41h is formed on the inner surface of the processing fluid rectifier plate 41 for the pin 48a of the plunger 48 to be inserted. The plunger 48 and the recess 41h constitute a fixing mechanism for fixing the workpiece pressing part 46 to the processing fluid rectifier plate 41. If the workpiece pressing part 46 is inserted from above into the space between a pair of processing fluid rectifier plates 41 along the processing fluid rectifier plate 41, the pin 48a, which is forced outward by the spring 48b, contacts the processing fluid rectifier plate 41 and is pressed into the interior of the holes 52-1 to 52-4. Figure 5 As shown, if the workpiece pressing part 46 moves to a position where the plunger 48 and the recess 41h are opposite each other, a portion of the pin 48a is embedded in the recess 41h, thereby fixing the workpiece pressing part 46 to a pair of processing fluid rectifier plates 41.

[0052] like Figure 4 As shown, in the workpiece pressing part 46, an elasto-plastic body 55 made of rubber or clay is installed on the arc-shaped portion that contacts the workpiece W. If the workpiece pressing part 46 slides along the processing fluid rectifier plate 41 while gradually pressing against the workpiece W, the elasto-plastic body 55 deforms. The deformed elasto-plastic body 55... Figure 5As shown in the right figure, the sheet metal of the workpiece W is pressed into multiple machining grooves Wz formed on the workpiece W, filling the machining grooves Wz, and the front end of the sheet metal of the workpiece W being cut is fixed. As a result, vibration of the sheet metal caused by the flow of machining fluid or adhesion between the sheet metals is suppressed, preventing the gap between the sheet metals from narrowing or becoming blocked. The gap change of the sheet metals during processing is reduced, and the width of the machining groove between adjacent sheet metals is stable. As a result, the machining fluid supplied from the machining fluid outlet of the machining fluid discharge prevention plate 43 to the inside of the machining fluid flow path restriction part 400 becomes static pressure inside the machining fluid flow path restriction part 400, and is evenly pressed into the machining grooves Wz formed on the workpiece W. The machining fluid pressed into each electrode moves towards the machining fluid outlet 51 provided on the workpiece pressing part 46 in the machining grooves Wz generated by electrical discharge machining, and is discharged from the machining fluid outlet 51 to the outside of the workpiece W. Therefore, to prevent the retention of machining chips between thin plates, reduce the secondary discharge to the machining chips, and perform stable electrical discharge machining.

[0053] Figure 6 This is a block diagram illustrating a structural example of the control unit 300 included in the wire electrical discharge machining apparatus 1000 according to Embodiment 1. The control unit 300 includes a machining control device 31, a discharge waveform control device 32, a machining state acquisition unit 33, a cutting table drive control device 34, a wire travel control device 35, and a workpiece pressing part holding control device 36. The control unit 300 controls the wire electrical discharge machining apparatus 1000.

[0054] The machining status acquisition unit 33 acquires various machining status information ps, including the position of the workpiece W in the z-axis direction, from the outputs of various sensors, and outputs the acquired machining status information ps to the machining control device 31. The machining control device 31 controls the discharge waveform control device 32, the cutting table drive control device 34, and the wire travel control device 35 based on the acquired machining status information ps. The discharge waveform control device 32 controls the machining power supply 5 based on the discharge waveform command wc input from the machining control device 31, controlling the voltage waveform applied between the electrodes or the current waveform flowing between the electrodes. The wire travel control device 35 drives the spool rotation control devices 8a and 8b based on the wire electrode travel command rc input from the machining control device 31, controlling the travel of the wire electrode 1.

[0055] The cutting table drive control device 34 drives the cutting feed table 10 based on the table command sc input from the processing control device 31, and controls the relative position between the workpiece W and the cutting line 1b. Additionally, the cutting table drive control device 34 also sends a table command sc to the workpiece pressing and holding device 36 connected to the workpiece pressing and holding device 47. Based on the table command sc from the cutting table drive control device 34, the workpiece pressing and holding device 36 monitors the coordinate value of the cutting feed table 10 in the z-axis direction. Simultaneously with the cutting feed table 10 reaching a preset first position, the holding mechanism 47a of the workpiece pressing and holding device 47 retracts via the pressing and holding control command qc, releasing the holding state of the workpiece pressing part 46.

[0056] Figure 7 This is a flowchart illustrating the operation of the wire electrical discharge machining apparatus 1000 during the cutting process according to Embodiment 1. Figure 8 This is a cross-sectional view showing the first stage of operation of the wire electrical discharge machining apparatus 1000 according to Embodiment 1 during the cutting process. Figure 9 This is a cross-sectional view showing the second stage of operation during the cutting process of the wire electrical discharge machining apparatus 1000 according to Embodiment 1. Figure 10 This is a cross-sectional view showing the third stage of operation during the cutting process of the wire electrical discharge machining apparatus 1000 according to Embodiment 1. (The image is inserted here.) Figures 7-10 The operation of the wire electrical discharge machining device 1000 during the cutting process is explained.

[0057] At the start of the cutting process, the cutting line 1b is supported in a state where it passes through the nozzle 7b and a through hole 43a of a processing fluid discharge prevention plate 43 fixed to the nozzle 7b, passes directly above the workpiece W which is sandwiched between two processing fluid rectifier plates 41, and passes through another through hole 43a of a processing fluid discharge prevention plate 43 fixed to the nozzle 7a and the nozzle 7a. The cutting line 1b travels in this state. With the processing fluid filling the processing tank (not shown), power from the processing power supply 5 is supplied to the cutting line 1b via the power supply units 6a and 6b.

[0058] If the cutting process begins, the control unit 300 holds the workpiece pressing part 46 in the initial cutting position via the workpiece pressing and holding device 47 (steps S100, S110). The initial cutting position is the position where the workpiece W and the cutting line 1b are separated upwards. Furthermore, at this initial cutting position, the lower end of the workpiece pressing part 46 is inserted into the rectangular area formed by the two processing fluid rectifier plates 41 and the two processing fluid discharge prevention plates 43. The reason for not allowing the workpiece pressing part 46 to contact and fix itself to the workpiece W at the initial cutting position is to avoid interference between the workpiece pressing part 46 and the cutting line 1b. Figure 8 The left figure shows the workpiece pressing part 46 held in the initial cutting position. Figure 8 In the state shown in the left figure, the workpiece pressing part 46 separates upwards from the workpiece W and the cutting line part 1b, and the plunger 48 is in the position separated from the recess 41h. Figure 8 In the state shown in the left figure, the holding mechanism 47a of the workpiece pressing and holding device 47 extends and engages with the fitting portion 46a of the workpiece pressing portion 46. Therefore, in this... Figure 8 In the state shown in the left figure, the workpiece pressing part 46 holds the position in the z-axis direction by the workpiece pressing and holding device 47.

[0059] The machining fluid supplied from nozzles 7a and 7b to the machining fluid flow path restriction section 400 is restricted in its flow by the machining fluid straightener 41 inside the machining fluid flow path restriction section 400, causing it to collide with the workpiece W. In the machining fluid flow path restriction section 400, the flow path of the machining fluid is restricted only by the cut portion 46b of the workpiece pressing portion 46 and the machining fluid outlet 51, which are arranged at the upper part of the machining fluid flow path restriction section 400. Therefore, the machining fluid rebounding from the workpiece W, etc., passes through the gap between the workpiece W and the workpiece pressing portion 46, and is discharged through the cut portion 46b of the workpiece pressing portion 46 and the machining fluid outlet 51.

[0060] If the cutting process begins, the control unit 300 raises the cutting feed table 10 (step S120). As a result, the workpiece fixing plate 42 and the pair of processing fluid rectifier plates 41 on the cutting feed table 10 rise relative to the pair of processing fluid discharge prevention plates 43. Figure 8 The right figure shows the state where, with the workpiece pressing part 46 held in the initial cutting position, the workpiece fixing plate 42 and the pair of processing fluid rectifier plates 41 rise slightly relative to the pair of processing fluid discharge prevention plates 43 as the cutting feed table 10 rises. Figure 8 In the right figure, the upper central portion of the workpiece W is cut off via the cutting line 1b. Figure 8 In the right figure, the plunger 48 is still in the position separated from the recess 41h, and the workpiece pressing part 46 is held in the z-axis direction by the workpiece pressing and holding device 47.

[0061] If the feed table 10 is raised further, then as Figure 9 As shown in the left figure, the processing fluid rectifier plate 41 rises relative to the workpiece pressing portion 46, and the plunger 48 engages with the recess 41h. As a result, the workpiece pressing portion 46 is locked and fixed to the two processing fluid rectifier plates 41 (step S130). Furthermore, as... Figure 9 As shown in the left figure, the cutting of the upper central portion of the workpiece W is further carried out by the cutting line 1b. Figure 9As shown in the left figure, when the processing progresses to the point where the workpiece pressing part 46 is in complete contact with the outer peripheral surface of the workpiece W, and a part of the workpiece pressing part 46 does not interfere with the cutting line part 1b, the plunger 48 engages with the recess 41h.

[0062] The processing distance of the workpiece pressing part 46 from the start of the cutting process to the operation of the aforementioned plunger mechanism 52 is designed based on the diameter of the workpiece W and the shape of the arc portion of the workpiece pressing part 46. The workpiece pressing and holding device 47 adjusts the holding position of the workpiece pressing part 46, i.e., the initial cutting position, so that the plunger 48 operates until the processing progresses to a position where a portion of the workpiece pressing part 46 does not interfere with the cutting line portion 1b when it is in complete contact with the outer peripheral surface of the workpiece W.

[0063] Furthermore, the first position and the positional relationship between the plunger 48 and the recess 41h are set so that the cutting feed table 10 reaches a preset first position simultaneously with the plunger 48 engaging with the recess 41h. Therefore, in the control unit 300, at the moment the plunger 48 engages with the recess 41h, the coordinate value of the monitored cutting feed table 10 in the z-axis direction is detected to have reached the first position (step S140: Yes). In response to this detection, the control unit 300 outputs a press-hold control command qc to the workpiece press-hold device 47. As a result, as... Figure 9 As shown in the right figure, the holding mechanism 47a of the workpiece pressing and holding device 47 retracts, and the holding state of the workpiece pressing part 46 is released (step S150).

[0064] The first position is set at an appropriate distance from the cross-sectional diameter of the workpiece W, or the maximum cutting length. For example, in a cylindrical workpiece W with a diameter of 6 inches, the first position can be set as the coordinate value after machining approximately 20mm to 25mm from the outer circumference of the cylinder where the cutting begins. This is because even for a large-diameter workpiece W with a cutting length exceeding 6 inches, if the machining in the Z direction is approximately 20mm after the start of machining, the thin plate portion after machining is still small. Therefore, the rigidity of the thin plate is high, and the thin plate portion hardly wobbles, allowing the machining fluid to flow fully into the machining tank, thus enabling stable electrical discharge machining. In addition, in the above, the first position is detected by the coordinate value in the Z-axis direction of the cutting feed stage 10, but it can also be detected by the position of the workpiece W, the position of the workpiece fixing plate 42 that mounts the workpiece W, or the position of the pair of machining fluid rectifier plates 41.

[0065] Furthermore, since the workpiece pressing part 46 moves slower in the z-axis direction due to the cutting feed table 10 than the operating speed of the holding mechanism 47a of the workpiece pressing and holding device 47, the table feed and discharge pulse oscillation performed by the cutting feed table 10 will not be temporarily interrupted, and the thin plate processing performed by the wire discharge machining will be performed continuously.

[0066] Then, the holding state of the workpiece pressing part 46, achieved by the workpiece pressing and holding device 47, is released, and the workpiece pressing part 46 is locked and fixed to the two processing fluid rectifier plates 41. Therefore, as Figure 10 As shown, if the cutting feed table 10 rises further, the workpiece pressing part 46, locked and fixed to the two processing fluid rectifier plates 41, rises together with the two processing fluid rectifier plates 41 and the workpiece fixing plate 42 on which the workpiece W is placed. This rise further advances the cutting of the workpiece W via the cutting line part 1b, cutting out multiple plate-shaped components from the workpiece W.

[0067] If the coordinate value of the cut-off feed table 10 in the z-axis direction reaches the value indicating the end of the cut-off process (step S160: Yes), the rising motion of the cut-off feed table 10 stops (step S170).

[0068] Furthermore, the first position can be determined by machine learning based on the results of the cutting process, the parameters during processing, and the depth of cut at the moment when the workpiece pressing part 46 grips the thin plate portion cut from the workpiece W.

[0069] As described above, according to Embodiment 1, the cutting process begins when the workpiece pressing part 46 is held in the initial cutting position by the workpiece pressing and holding device 47. Then, if the coordinate value of the cutting feed table 10 in the z-axis direction reaches the first position, the holding of the workpiece pressing part 46 by the workpiece pressing and holding device 47 is released, and then the cutting process is performed while the workpiece pressing part 46 is locked and fixed by the two processing fluid rectifier plates 41. That is, during the cutting process, the workpiece pressing part 46 is not driven to move up and down, but is only held in the initial cutting position, thereby holding the workpiece W by the workpiece pressing part 46. Therefore, it is not necessary to control the movement of the workpiece pressing part 46 together with the cutting feed table 10, and wire EDM can be realized with simple control. In addition, by locking the workpiece pressing part 46 to the two processing fluid rectifier plates 41, the workpiece pressing part 46 is held in contact with the workpiece W, so there is no need for the reinforcement of the stage mechanism.

[0070] Furthermore, the machining fluid flow path restriction section 400, which includes a workpiece pressing section 46 with a machining fluid outlet 51, a pair of machining fluid rectifier plates 41, a pair of machining fluid discharge prevention plates 43, and a workpiece fixing plate 42, ensures a stable supply of machining fluid between the electrodes, preventing localized accumulation of machining chips and enabling continuous wire EDM. This reduces secondary discharge to machining chips, suppresses partial discharge, and efficiently cools the wire electrodes, allowing for higher EDM speeds. Additionally, it reduces fluctuations in the thickness of the cut plate-shaped component, minimizes machining marks on the machined surface, and reduces the probability of wire electrode breakage.

[0071] Implementation method 2.

[0072] Figure 11 This is an exploded perspective view showing a structural example of the machining fluid flow path restriction section 500 of the wire electrical discharge machining apparatus according to Embodiment 2. In Embodiment 2, the machining fluid flow path restriction section 400 of Embodiment 1 is replaced by the machining fluid flow path restriction section 500. In the machining fluid flow path restriction section 500, the machining fluid discharge prevention plate 43 of Embodiment 1 is replaced by the machining fluid discharge prevention plate 60. The other structures of Embodiment 2 are the same as those of Embodiment 1, and repeated descriptions are omitted.

[0073] One processing fluid discharge prevention plate 60 consists of two plates, including a nozzle side plate 60a connected to the nozzle 7a and a rectifier plate side plate 60b in contact with the processing fluid rectifier plate 41. The other processing fluid discharge prevention plate 60 consists of two plates, including a nozzle side plate 60a connected to the nozzle 7b and a rectifier plate side plate 60b in contact with the processing fluid rectifier plate 41. The opposing surfaces of the nozzle side plate 60a and the rectifier plate side plate 60b are connected by a spring 61. Furthermore, holes machined in the nozzle side plate 60a and the rectifier plate side plate 60b are connected by a processing fluid supply pipe 62.

[0074] For example, a compression spring is used for spring 61, so that even when the nozzle side plate 60a and the rectifier plate side plate 60b cannot be arranged parallel, the rectifier plate side plate 60b is pressed against the processing fluid rectifier plate 41 by the restoring force generated when the spring 61 is bent. The processing fluid supply pipe 62 is a flexible pipe such as a corrugated one, through which the processing fluid supplied from the nozzles 7a and 7b and the cutting line section 1b pass.

[0075] When the workpiece W is a semiconductor material, the angle of the cut surface relative to the crystal direction of the semiconductor material affects the electrical characteristics of the semiconductor manufactured from the wafer produced by the cut process. Therefore, the cutting direction of the thin plate is finely adjusted through a changeover adjustment process before the cut process. Specifically, a rotary table (not shown) is provided between the workpiece fixing plate 42 and the cut feed table 10 to rotate the workpiece fixing plate 42. This rotary table adjusts the relative angle between the reference end face of the workpiece W fixed on the workpiece fixing plate 42 and the cut line portion 1b. This relative angle adjustment is basically to a value less than or equal to a few degrees, even if the relative angle is large. However, since the contact surfaces of the workpiece fixing plate 42 and the processing fluid rectifier plate 41 with the rectifier plate side plate 60b rotate along the z-axis, a gap is generated in the processing fluid discharge prevention plate 43 of Embodiment 1, and processing fluid may leak out.

[0076] In contrast, the processing fluid discharge prevention plate 60 according to Embodiment 2 is configured as two independently movable pieces: a nozzle side plate 60a connected to the nozzles 7a and 7b and a rectifier plate side plate 60b in contact with the processing fluid rectifier plate 41. Therefore, when the relative angle is adjusted, the spring 61 will also maintain the contact state of the rectifier plate side plate 60b.

[0077] As described above, according to Embodiment 2, the processing fluid discharge prevention plate 60 is configured as a two-piece structure consisting of a nozzle side plate 60a and a rectifier plate side plate 60b with a clamping spring 61. Therefore, even when adjusting the angle of the cutting surface, no leakage of processing fluid will occur.

[0078] Figure 12 This is a block diagram illustrating an example of the hardware structure of the control unit 300 included in the wire electrical discharge machining apparatus according to embodiments 1 and 2. The control unit 300 can... Figure 12 The processor 101, memory 102, and interface circuit 103 shown are implemented as follows. Examples of processor 101 include CPU (Central Processing Unit), central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, DSP (Digital Signal Processor), or system LSI (Large Scale Integration) circuit. Examples of memory 102 include RAM (Random Access Memory) and ROM (Read Only Memory).

[0079] The control unit 300 is implemented by the processor 101 reading and executing a program stored in the memory 102 for performing the actions of the control unit 300. This program can be described as instructing the computer to execute a sequence or method of the control unit 300. The memory 102 also serves as temporary storage when the processor 101 performs various processes. The interface circuit 103 is the connection interface with external instruments connected to the control unit 300. Furthermore, regarding the functions of the control unit 300, some can be implemented using dedicated hardware, and some can be implemented using software or firmware.

[0080] The structures shown in the above embodiments represent a part of the content of the present invention and can also be combined with other known technologies. Without departing from the spirit of the present invention, parts of the structure can be omitted or modified.

[0081] Explanation of the label

[0082] 1. Wire electrode, 1a. Parallel wire section, 1b. Wire cutting section, 2. Guide rollers 2-1 to 2-4, 3. Wire spools 3-1 and 3-2, 4a and 4b. Vibration damping guide rollers, 5. Power supply for processing, 6a and 6b. Power supply unit, 7a and 7b. Nozzles, 8a and 8b. Wire spool rotation control device, 9a and 9b. Traverse control device, 10. Cutting feed table, 31. Processing control device, 32. Discharge waveform control device, 33. Processing status acquisition unit, 34. Cutting table drive control device, 35. Wire travel control device, 36. Workpiece pressing part holding control device, 41. Processing fluid rectifier plate, 41h. Recess, 42. Workpiece fixing plate, 43 and 60. Processing fluid discharge prevention plate, 4 3a Through hole, 46 Workpiece pressing part, 46a Fitting part, 46b Cutting part, 47 Workpiece pressing and holding device, 47a Holding mechanism, 47b Up and down moving mechanism, 48 Piston, 48a Pin, 48b, 61 Spring, 51 Processing fluid outlet, 52-1 to 52-4 Holes, 55 Elastic-plastic body, 56 Elastic body, 60a Nozzle side plate, 60b Rectifier plate side plate, 62 Processing fluid supply pipe, 100 Processing mechanism part, 101 Processor, 102 Memory, 103 Interface circuit, 200 Power supply part, 300 Control part, 400, 500 Processing fluid flow path restriction part, 1000 Wire EDM device, W Workpiece, Wz Processing groove.

Claims

1. A wire electrical discharge machining apparatus, characterized in that, have: A wire electrode having cutting wire portions arranged side-by-side and separated from each other, facing the workpiece; A power supply unit that causes a discharge between the plurality of said cutting wires and the workpiece; A pair of nozzles having a plurality of ejection holes through which a plurality of said cutting lines are inserted and through, supplying processing fluid to the gap between the plurality of said cutting lines and the workpiece; A workpiece fixing plate, which holds and fixes the workpiece. A pair of processing fluid rectifier plates are disposed on both sides of the workpiece in a manner that clamps the workpiece. A pair of processing fluid discharge prevention plates are provided in such a way that they clamp the workpiece fixing plate and the pair of processing fluid rectifier plates, and have a plurality of through holes that are connected to a plurality of the ejection holes of the pair of nozzles and allow a plurality of the cutting line portions to be inserted through them. The workpiece pressing part is inserted from above the workpiece and the plurality of cutting lines into a space surrounded by a pair of processing fluid rectifier plates and a pair of processing fluid discharge prevention plates to hold the workpiece that has been broken during cutting. The cutting feed table causes the workpiece fixing plate and the pair of processing fluid rectifier plates to move vertically relative to the pair of processing fluid discharge prevention plates and the plurality of cutting lines. A holding device that holds the workpiece pressing portion in the initial cutting position, separating it upwards from the cutting line portion; as well as The control unit drives the cutting feed table to move upward relative to the pair of processing fluid discharge prevention plates when the cutting process begins, so that the workpiece fixing plate and the pair of processing fluid rectifier plates that fix the workpiece approach the plurality of cutting lines. The control unit controls the holding device to keep the workpiece pressing part in the initial cutting position by moving upward until the workpiece reaches the first position. The control unit also controls the holding device to release the holding of the workpiece pressing part after the workpiece reaches the first position.

2. The wire electrical discharge machining apparatus according to claim 1, characterized in that, It has a fixing mechanism that, if the workpiece reaches the first position, locks the pressing part of the workpiece to a pair of processing fluid rectifier plates. The control unit controls the process in such a way that, after the workpiece reaches the first position, while the workpiece pressing part is locked and fixed to the pair of processing fluid rectifier plates by the fixing mechanism, the cutting feed table is driven to move the workpiece fixing plate and the pair of processing fluid rectifier plates relative to the pair of processing fluid discharge prevention plates upward until the end of the cutting process, thereby cutting the workpiece.

3. The wire electrical discharge machining apparatus according to claim 2, characterized in that, The workpiece pressing part has multiple bottom holes. The fixing mechanism has a plurality of spring-loaded plungers respectively provided with the plurality of bottom holes in the workpiece pressing portion, and a plurality of recesses for engaging the plurality of spring-loaded plungers provided in a pair of rectifier plates.

4. The wire electrical discharge machining apparatus according to any one of claims 1 to 3, characterized in that, The workpiece pressing part has a processing fluid outlet that extends from the lower surface to the upper surface.

5. The wire electrical discharge machining apparatus according to any one of claims 1 to 4, characterized in that, An elastomer is provided on the surface of the workpiece pressing part that contacts the processing fluid discharge prevention plate, the surface of the pair of processing fluid rectifier plates that contacts the processing fluid discharge prevention plate, and the portion of the workpiece fixing plate that contacts the processing fluid discharge prevention plate.

6. The wire electrical discharge machining apparatus according to any one of claims 1 to 5, characterized in that, The surface of the workpiece pressing part that contacts the workpiece is shaped along the outer periphery of the workpiece, and an elastic-plastic body is provided on the surface of the workpiece pressing part that contacts the workpiece.

7. The wire electrical discharge machining apparatus according to any one of claims 1 to 6, characterized in that, The pair of processing fluid discharge prevention plates are each clamped by a pair of side plates of a spring.

8. A wire electrical discharge machining apparatus, characterized in that, have: The first component is used to support the cutting line section; The second component fixes the workpiece in place and, together with the first component, forms a space from the first component into the workpiece for the processing fluid to flow. The third component, which is held at the initial cutting position separating upward from the cutting line, is inserted into the space to hold the workpiece that has been separated during the cutting from above; A fixing mechanism that locks and fixes the third component relative to the second component; and The control unit controls the process in such a way that, if the cutting process begins, the second component carrying the workpiece moves upward relative to the first component, bringing the second component closer to the third component and the plurality of cutting lines, and holds the third component at the initial cutting position until the workpiece reaches the first position. If the workpiece reaches the first position, the holding is released. After the workpiece reaches the first position, with the third component locked to the second component by the fixing mechanism, the second component carrying the workpiece moves upward relative to the first component until the cutting process ends, thereby cutting the workpiece.

9. A wire electrical discharge machining method, characterized in that, have: The first component is used to support the cutting line section; The second component fixes the workpiece in place and, together with the first component, forms a space through which the processing fluid flows from the first component into the workpiece. as well as The third component, held at the initial cutting position separating upwards from the cutting line, is inserted into the space to hold the workpiece separated during the cutting process from above. If the cutting process begins, the second component carrying the workpiece is moved upward relative to the first component, bringing the second component closer to the third component and the plurality of cutting lines. The third component is held in the initial cutting position until the workpiece reaches the first position. After the workpiece reaches the first position, the holding is released. With the third component fixed to the second component, the second component carrying the workpiece is moved upward relative to the first component until the cutting process is completed, thereby cutting the workpiece.

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