Wire electrical discharge machining apparatus, wire electrical discharge machining method, and wafer manufacturing method

Abstract

The wire electric discharge machining apparatus includes: a pair of electrically conductive working fluid rectifying plates connected to a power source and provided so as to be in contact with both sides of a workpiece so as to sandwich the workpiece; a pair of nozzles (7a, 7b) having a plurality of working fluid ejection holes (7c) through which the plurality of cutting line sections (1b) are inserted, which eject a working fluid toward a space sandwiched by the pair of working fluid rectifying plates, and which supply the working fluid to a gap between the plurality of cutting line sections (1b) and the workpiece (W); a cutting feed table that moves the pair of working fluid rectifying plates up and down relative to the plurality of cutting line sections (1b); a to-be-processed object pressing part (72) for holding the to-be-processed object (W), which has been broken during the cutting process, from above the to-be-processed object (W) and the plurality of cutting line parts (1b); and a lower workpiece holding unit that holds the workpiece (W) by contacting the workpiece (W) from below, the lower workpiece holding unit having electrical conductivity.

Description

Technical Field

[0001] The present invention relates to a wire discharge machining device, a wire discharge machining method, and a wafer manufacturing method for performing discharge machining for cutting out a plurality of plate-like members at once from a workpiece using a wire electrode. Background Art

[0002] In a multi-wire electrical discharge machining device, electrical discharge is generated between a plurality of wire electrodes and a workpiece, and a plurality of plate-like parts are cut out from the workpiece at once. In the simultaneous cutting of a plurality of plate-like parts by electrical discharge machining, a plurality of grooves are formed in the workpiece at the positions of the plurality of portions of the wire electrodes, i.e., the wire cutting portions. Furthermore, the wire cutting portions enter the plurality of grooves respectively, and the grooves are continuously deepened. Furthermore, the grooves reach the ends of the workpiece, thereby simultaneously generating a plurality of thin plates.

[0003] In the machining gap between thin plates in the middle of the process, that is, in the EDM, heat energy and machining chips are always generated due to the discharge. The heat energy and machining chips generated by the discharge will become the cause of the EDM becoming unstable. Therefore, for the purpose of removing the machining chips and cooling the inter-electrode, an attempt is made to supply the machining fluid to the inter-electrode through the machining fluid nozzle from the machining fluid supply device to eliminate the machining instability factor. In order to properly supply the machining fluid to the inter-electrode, the machining fluid nozzle is configured to be as close as possible to the workpiece, and the machining fluid is properly supplied to the inter-electrode.

[0004] For example, Patent Document 1 discloses a structure in which a voltage is applied to a gap formed between a wire electrode and a workpiece in a machining fluid to cause discharge, thereby machining the workpiece. In this wire discharge machining machine, machining fluid is supplied to the gap between electrodes from a machining fluid supply device via a machining fluid nozzle for the purpose of inter-electrode cooling and chip discharge in response to heat energy and machining chips caused by discharge generated in the machining gap during discharge machining. In order to properly supply the machining fluid to the inter-electrode, the machining fluid nozzle is placed as close to the workpiece as possible.

[0005] In addition, Patent Document 2 discloses a holding device, which includes: a holding portion that holds an ingot during electrical discharge machining in which an ingot is cut at intervals where wires are arranged in parallel; and a current-carrying portion that conducts current to the ingot so that current flows through the ingot. The holding device eliminates the ingot holding portion for each material and the ingot mixing in the area where electrical discharge machining is performed while holding the ingot so that it does not fall, thereby reducing the instability of electrical discharge machining caused by simultaneous electrical discharge of different materials, preventing wire breakage, and stabilizing machining.

[0006] Patent Document 1: International Publication No. 2020 / 213040

[0007] Patent Document 2: Japanese Patent Application Publication No. 2015-120235 Summary of the invention

[0008] In Patent Document 1, the method for fixing the workpiece is to increase the contact area with the cutting end face fixing block provided on the fixture plate, to improve the holding force against the swing of each thin plate in the process of forming, and to fix the workpiece by using the oriented plane portion of the workpiece through a conductive adhesive or the like. In addition, it is possible to conduct power from the cutting end face fixing block so that the power supply path to the workpiece is not interrupted until the thin plate is cut. However, when the workpiece is fixed only by the processing end portion, if the diameter of the thin plate of the processing object becomes larger, in order to prevent the thin plate from breaking, it is necessary to significantly reduce the flow rate of the machining fluid, and the discharge machining speed may be sharply reduced due to poor chip discharge or insufficient wire cooling.

[0009] Patent document 2 considers the following situation, that is, since the workpiece is lowered relative to the wire electrode while the discharge machining is performed, the influence of the deadweight caused by the reduction of the bending rigidity of the thin plate due to the large diameter is small. However, when the method of patent document 2 is applied to patent document 1, it becomes a structure that suppresses the deflection of the thin plate caused by the pressure of the machining fluid flow by two wafer pressing parts opposite to one holding part. In particular, the wafer pressing part is a polyurethane or sponge-like material. When subjected to a strong machining fluid flow, the material itself is deformed or slips relative to the outer peripheral surface of the thin plate. In addition, it is configured to press the thin plate at a position away from the cutting end portion of the thin plate, so it is difficult to prevent the rupture of the cutting end portion caused by the deflection of the large-diameter thin plate.

[0010] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to obtain a wire electrical discharge machining device capable of preventing damage to a thin plate when the thin plate is cut.

[0011] In order to solve the above problems and achieve the purpose, the wire discharge machining device according to the present invention generates discharge between a plurality of advancing cutting wires and a workpiece, performs discharge machining on the workpiece by the energy of the discharge, and simultaneously cuts a plurality of wafers from the workpiece. The wire discharge machining device comprises: a wire electrode which is separated from each other in parallel and has a plurality of cutting wires facing the workpiece; a power supply unit which generates discharge between the plurality of cutting wires and the workpiece; a pair of machining fluid rectifying plates which are connected to a power supply, are provided in contact with both sides of the workpiece in a manner of sandwiching the workpiece, and have conductivity; and a pair of nozzles which have a plurality of machining fluid ejection holes which are inserted through the plurality of cutting wires, eject machining fluid toward a space sandwiched by the pair of machining fluid rectifying plates, and supply machining fluid to the gaps between the plurality of cutting wires and the workpiece. The wire discharge machining device comprises: a cutting feed table, which enables a pair of machining fluid rectifying plates to move up and down relative to a plurality of cutting line portions; a workpiece pressing portion, which holds the workpiece separated during the cutting process from above the workpiece and the plurality of cutting line portions; and a lower workpiece holding portion, which holds the workpiece by contacting the workpiece from below and having conductivity.

[0012] Effects of the Invention

[0013] The wire electrical discharge machining device according to the present invention has an effect of preventing damage to a thin plate when the thin plate is cut. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a conceptual diagram showing a configuration example of the wire electrical discharge machining device according to the first embodiment.

[0015] Figure 2 It is a perspective view showing the positional relationship between a thin plate machining stabilization portion, a peripheral mechanism of the thin plate machining stabilization portion, and the thin plate machining stabilization portion included in the wire electrical discharge machining device according to the first embodiment.

[0016] Figure 3 It is a cross-sectional view showing the internal structure of a thin plate machining stabilization portion included in the wire electrical discharge machining device according to the first embodiment.

[0017] Figure 4 It is a diagram showing a power supply path from the machining power supply to the electrical discharge machining power supply of the workpiece in the wire electrical discharge machining device according to the first embodiment.

[0018] Figure 5 This is a block diagram showing a configuration example of a control unit included in the wire electrical discharge machining device according to the first embodiment.

[0019] Figure 6 This is a flowchart showing the operation of the wire electrical discharge machining device according to the first embodiment during cutting processing.

[0020] Figure 7 It is a first perspective view showing a state of a thin plate during cutting processing in a thin plate processing stabilization section included in the wire electrical discharge machining apparatus according to the first embodiment.

[0021] Figure 8 It is a second perspective view showing a state of the thin plate processing stabilization section included in the wire electrical discharge machining apparatus according to the first embodiment during the cutting processing of the thin plate.

[0022] Fig. 9 This is a diagram for explaining the relationship between the cutting position of a workpiece and the cutting length during cutting processing by the wire electrical discharge machining device according to the first embodiment.

[0023] Fig.10 It is a schematic diagram showing a configuration example of a workpiece power supply auxiliary unit included in the wire electrical discharge machining apparatus according to the second embodiment.

[0024] Fig.11 This is a conceptual diagram showing an example of a state immediately before the completion of the cutting process of a thin plate in the wire electrical discharge machining device according to the first embodiment.

[0025] Fig.12 Yes Fig.11 An enlarged view showing a specific area in the image.

[0026] Fig.13 This is a conceptual diagram showing an example of a state immediately before the completion of the cutting process of a thin plate in the wire electrical discharge machining device according to the second embodiment.

[0027] Fig.14 Yes Fig.13 An enlarged view showing a specific area in the image.

[0028] Fig.15 It is a schematic diagram showing a configuration example of a thin plate side surface holding portion of a thin plate machining stabilizing portion included in the wire electrical discharge machining apparatus according to the third embodiment.

[0029] Fig.16 Yes Fig.15 An enlarged view showing a specific area in the image.

[0030] Fig.17 Yes Fig.15 Other magnified images showing specific areas in the image.

[0031] Fig.18 This is a diagram showing a hardware configuration in which the functions of a control unit included in the wire electrical discharge machining device are realized by dedicated hardware.

[0032] Fig.19 Yes means Fig.18 The diagram is a diagram of a hardware configuration in which the functions of the control unit included in the wire electrical discharge machining device are realized by a processor executing a program stored in a memory. DETAILED DESCRIPTION

[0033] Hereinafter, a wire electrical discharge machining device, a wire electrical discharge machining method, and a wafer manufacturing method according to embodiments will be described in detail with reference to the drawings.

[0034] Implementation method 1.

[0035] The multi-wire electrical discharge machining device is used, for example, in the semiconductor manufacturing process to cut a plurality of semiconductor wafers from an ingot at once, i.e., to perform a collective cutting process of a plurality of semiconductor wafers. As the collective cutting process proceeds, the thin plate to be cut off from the ingot increases in the thin plate portion that becomes the semiconductor wafer, and decreases in the portion that is integrated with the ingot. Moreover, before the collective cutting process is completed, the adjacent thin plates are connected to each other by a small amount of remaining processed portions.

[0036] The thin plate in this state swings due to the flow of machining fluid supplied to the gap between the ingot and the wire, i.e., the inter-electrode gap, or, for example, in a thin plate having a diameter greater than or equal to 6 inches, the weight of the thin plate itself also increases, causing the thin plate to bend. As a result, especially in a thin plate with a large diameter relative to the plate thickness, the stress generated by the bending will concentrate near the remaining processed portion, and cracks starting from the remaining processed portion are likely to occur. Even for high-hardness materials such as silicon carbide (SiC) and gallium nitride (GaN) with relatively high hardness, if the diameter becomes larger relative to the thickness of the semiconductor wafer, the semiconductor wafer may swing or bend due to the decrease in the rigidity of the semiconductor wafer itself or the force received from the machining fluid flow.

[0037] In the case of a semiconductor wafer, if a portion of the semiconductor wafer is cracked or missing, it causes a problem such as a reduction in yield during the grinding process of the cut semiconductor wafer or in the semiconductor manufacturing process after the grinding process. Therefore, the cracking or missing of the semiconductor wafer becomes a cause of significant loss of the commodity value of the semiconductor wafer.

[0038] That is, in electrical discharge machining in which a wire electrode is used to cut off multiple plate-like components from a workpiece at a time, in order to improve the discharge of machining chips generated by the electrical discharge and the cooling of the wire after being heated by the discharge energy, the flow rate of machining fluid supplied to the gap of the thin plate in the middle of formation is increased, and the pressure of the machining fluid flow received by the thin plate portion is increased, thereby causing the thin plate to swing. In addition, due to the decrease in the bending rigidity of the thin plate itself caused by the expansion of the diameter relative to the thickness of the thin plate, the thin plate in the middle of formation gradually becomes easily bent.

[0039] Furthermore, the pressure of the machining fluid flow acts on the thin plate, and stress concentration occurs at the boundary between the formed thin plate portion and the remaining processed portion of the workpiece, or near the thin plate where the cutting is completed, which makes it easy for the thin plate to be cracked or missing. In the case of the workpiece, such as an ingot composed of crystals such as SiC or GaN, the diameter of the semiconductor wafer is increased, and the influence of the hydraulic pressure or the reduction of rigidity of the thin plate portion from the machining fluid flow during the discharge machining becomes more significant.

[0040] Hereinafter, not only a thin plate cut by cutting is referred to as a wafer, but also a workpiece with a machined groove formed thereon, that is, a part of the workpiece and a thin plate-shaped portion before being cut is also referred to as a wafer, a wafer in process, etc.

[0041] Figure 1 This is a conceptual diagram showing a configuration example of a wire electrical discharge machining device 1000 according to the first embodiment. Figure 2 It is a perspective view showing the positional relationship between the thin plate machining stabilization unit 70 , the peripheral mechanisms of the thin plate machining stabilization unit 70 , and the thin plate machining stabilization unit 70 included in the wire electrical discharge machining device 1000 according to the first embodiment. Figure 3 FIG. 2 is a cross-sectional view showing the internal structure of the thin plate machining stabilizing section 70 included in the wire electrical discharge machining device 1000 according to the first embodiment. Figure 3 , the state in which the wire discharge machining is performed on the workpiece W set on the machining fluid rectifying plate 71 until the position of about 1 / 3 of the total machining distance is shown. Figure 3 , a cross section at a position between a machining fluid rectifying plate 71a and a machining fluid rectifying plate 71b described later is shown. The wire electrical discharge machining device 1000 is a multi-wire electrical discharge machining device that performs electrical discharge machining using a wire electrode 1. Figure 2 and Figure 3 In FIG. 8 , arrow 81 shows the direction of travel of the cutting line portion 1 b. Figure 3 In FIG. 8 , arrow 82 shows the direction of flow of the machining fluid.

[0042] exist Figure 1, the x-axis, y-axis, and z-axis of the three-axis orthogonal coordinate system are shown. The y-axis direction corresponds to the traveling direction of the wire electrode 1 on the workpiece W, that is, the traveling direction of the wire electrode 1 relative to the workpiece W arranged in the online electrical discharge machining device 1000. The z-axis direction corresponds to the height direction of the wire electrical discharge machining device 1000. The height direction of the wire electrical discharge machining device 1000 corresponds to the up-down direction, that is, the vertical direction. The x-axis direction corresponds to the direction in which the wire electrode 1 is arranged on the workpiece W, that is, the direction in which the wire electrode 1 is arranged relative to the workpiece W arranged in the online electrical discharge machining device 1000. The x-axis direction can be said to be a direction parallel to the length direction of the workpiece W arranged in the online electrical discharge machining device 1000.

[0043] The wire discharge machining device 1000 includes: a machining mechanism unit 100 that performs discharge cutting machining on a workpiece W through a wire electrode 1; a power supply unit 200 that performs power supply; and a control unit 300 that controls the wire discharge machining device 1000. The wire discharge machining device 1000 cuts out a plurality of plate-like components from the workpiece W at once. Examples of materials of the workpiece W include tungsten, molybdenum, silicon carbide, single crystal silicon, single crystal silicon carbide, gallium arsenide, and polycrystalline silicon. Silicon carbide is also called silicon carbide. Hereinafter, discharge cutting machining may be referred to as cutting machining.

[0044] The processing mechanism 100 includes a plurality of guide rollers 2, a bobbin 3, vibration-damping guide rollers 4a, 4b, nozzles 7a, 7b, bobbin rotation control devices 8a, 8b, traverse control devices 9a, 9b, and a cutting feed table 10. The plurality of guide rollers 2 are composed of a guide roller 2a, a guide roller 2b, a guide roller 2c, and a guide roller 2d. The bobbin 3 is composed of a bobbin 3a and a bobbin 3b.

[0045] The plurality of guide rollers 2 guide the wire electrode 1 as it travels. The guide rollers 2a, 2b, 2c, and 2d are each rotatably disposed about a respective rotation axis. The guide rollers 2a, 2b, 2c, and 2d are disposed separately from each other and are disposed so that their rotation axes are parallel to each other. The rotation axes of the guide rollers 2a, 2b, 2c, and 2d are parallel to each other, thereby enabling the wire electrode 1 to travel with high precision. The rotation axes of the guide rollers 2a, 2b, 2c, and 2d are each disposed in parallel to the x-axis.

[0046] One wire electrode 1 is wound multiple times around guide rollers 2a, 2b, 2c, 2d at intervals in the direction of the respective rotation axes of the guide rollers 2a, 2b, 2c, 2d. These wire electrodes 1 are collectively referred to as a parallel wire section 1a. In addition, a portion of the parallel wire section 1a facing the workpiece W is referred to as a cutting wire section 1b. The cutting wire section 1b is composed of a plurality of parallel wire electrodes 1. The cutting wire sections 1b are preferably provided in parallel with each other.

[0047] A plurality of guide grooves 2e are formed at equal intervals on the surfaces of the guide rollers 2a, 2b, 2c, and 2d. The wire electrode 1 is wound along the plurality of guide grooves 2e on the surfaces of the guide rollers 2a, 2b, 2c, and 2d, and the guide rollers 2a, 2b, 2c, and 2d keep the intervals of the wire electrodes 1, that is, the intervals of the wire electrodes 1 of the parallel wire portions 1a, constant. In the wire discharge machining device 1000, the cutting wire portions 1b are arranged parallel to each other and at equal intervals, so that the thicknesses of the plurality of plate-like members cut from the workpiece W can be made equal, and the cross-sections of the plurality of plate-like members can be made parallel. In addition, the plurality of guide rollers 2 need not necessarily be four, and may be less than or equal to three, or may be greater than or equal to five.

[0048] The bobbins 3a and 3b advance the wire electrode 1 by the extraction and winding operations of the wire electrode 1. The bobbin 3a extracts the wire electrode 1. The bobbin 3b winds the wire electrode 1. The bobbin rotation control device 8a and the traverse control device 9a control the bobbin 3a. The bobbin rotation control device 8b and the traverse control device 9b control the bobbin 3b.

[0049] The bobbin rotation control device 8a controls the rotation of the bobbin 3a and controls the travel of the wire electrode 1. The bobbin rotation control device 8a controls, for example, the travel direction and travel speed of the wire electrode 1. The bobbin rotation control device 8b controls the rotation of the bobbin 3b and controls the travel of the wire electrode 1. The bobbin rotation control device 8b controls, for example, the travel direction and travel speed of the wire electrode 1.

[0050] The traverse control device 9a controls the position of the bobbin 3a in the x-axis direction in accordance with the extraction position of the wire electrode 1. The traverse control device 9b controls the position of the bobbin 3b in the x-axis direction in accordance with the winding position of the wire electrode 1. The position control of the bobbin 3a and 3b by the traverse control devices 9a and 9b is called traverse control. Through the traverse control, the bobbin 3a and 3b can stably and accurately move the wire electrode 1.

[0051] The wire electrode 1 drawn out from the bobbin 3a is wound around the guide rollers 2b, 2a, 2d, and 2c in sequence, and is wound around the guide roller 2b again. As described above, the wire electrode 1 is wound around the bobbin 3b after passing through the guide rollers 2a, 2b, 2c, and 2d a plurality of times.

[0052] The workpiece W is fixed inside the thin plate machining stabilizing section 70. The thin plate machining stabilizing section 70 will be described in detail later. The thin plate machining stabilizing section 70, which fixes the workpiece W inside, is provided between the vibration suppression guide roller 4a and the vibration suppression guide roller 4b. The vibration suppression 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 cutting wire section 1b. In addition, the portion of the parallel wire section 1a that faces the workpiece W is referred to as the cutting wire section 1b in the foregoing description, and the portion between the vibration suppression guide roller 4a and the vibration suppression guide roller 4b in the parallel wire section 1a is also referred to as the cutting wire section 1b. In addition, in the wire electric discharge machining device 1000, the vibration suppression guide roller 4a and the vibration suppression guide roller 4b can also be omitted.

[0053] The nozzle 7a is arranged between the vibration suppression guide roller 4a and the thin plate processing stabilizing portion 70. The nozzle 7b is arranged between the vibration suppression guide roller 4b and the thin plate processing stabilizing portion 70. The inside of the nozzles 7a and 7b is filled with a processing fluid supplied from a processing fluid supply pipe 74. The nozzles 7a and 7b have a plurality of processing fluid ejection holes 7c for ejecting the processing fluid filled inside toward the workpiece W in the thin plate processing stabilizing portion 70. The parallel line portion 1a is inserted through the plurality of processing fluid ejection holes 7c of the nozzles 7a and 7b and travels.

[0054] The cutting feed table 10 changes the relative position between the workpiece W and the cutting line portion 1b. Specifically, the cutting feed table 10 changes the relative position between the thin plate processing stabilizing portion 70 to which the workpiece W is fixed and the cutting line portion 1b. In the first embodiment, the position of the cutting line portion 1b in the z-axis direction is fixed, and the cutting feed table 10 is movable in the z-axis direction. The cutting feed table 10 moves the structural elements inside the thin plate processing stabilizing portion 70 together with the workpiece W in the up-down direction. The wire discharge machining device 1000 makes the workpiece W set in the thin plate processing stabilizing portion 70 relatively approach or depart from the cutting line portion 1b by moving the cutting feed table 10 in the up-down direction, and cuts the workpiece W. In addition, by performing discharge machining on the workpiece W, a machining groove Wg described later along the cutting line portion 1b is formed in the workpiece W. In addition, the cutting feed table 10 may also be movable in the x-axis direction, the y-axis direction, and the z-axis direction.

[0055] The processing mechanism 100 may include components such as a guide pulley for suppressing vibration of the wire electrode 1, a load cell for measuring the tension of the wire electrode 1, and a dancer roller for controlling the tension of the wire electrode 1. The processing mechanism 100 may maintain the tension of the wire electrode 1 within a range suitable for the travel of the wire electrode 1 through the load cell and the dancer roller. For example, the dancer roller may change the drawing speed and winding speed of the wire electrode 1, thereby controlling the tension of the wire electrode 1.

[0056] The power supply unit 200 includes a machining power supply 5 and power supply units 6a and 6b. The machining power supply 5 supplies power to the wire electrode 1 via the power supply units 6a and 6b. The machining power supply 5 supplies power to the workpiece W via the machining liquid rectifying plate 71a.

[0057] The thin plate processing stabilizing section 70 is a mechanism section for preventing poor power supply to each thin plate during cutting. The thin plate processing stabilizing section 70 is arranged between the vibration suppression guide roller 4a and the vibration suppression guide roller 4b and between the nozzle 7a and the nozzle 7b. The thin plate processing stabilizing section 70 includes a processing liquid rectifying plate 71a and a processing liquid rectifying plate 71b as a pair of processing liquid rectifying plates 71, a workpiece pressing section 72, a workpiece power supply auxiliary section 73, thin plate side holding sections 75a and 75b, and a workpiece pressing section holding device 78 described later.

[0058] The machining liquid rectifying plate 71a and the machining liquid rectifying plate 71b, which are a pair of machining liquid rectifying plates 71, are conductive and are arranged in parallel with the direction of travel of the cutting line 1b to rectify the flow of the machining liquid. The machining liquid rectifying plate 71a and the machining liquid rectifying plate 71b are arranged between the nozzle 7a and the nozzle 7b. The machining liquid rectifying plate 71a and the machining liquid rectifying plate 71b have a plate shape or a rectangular parallelepiped shape, and the surfaces facing each other are arranged in parallel. That is, the surface of the machining liquid rectifying plate 71a facing the machining liquid rectifying plate 71b, that is, the opposing surface 71as, and the surface of the machining liquid rectifying plate 71b facing the machining liquid rectifying plate 71a, that is, the opposing surface 71bs, are arranged in parallel. Moreover, the opposing surface 71as of the machining liquid rectifying plate 71a and the opposing surface 71bs of the machining liquid rectifying plate 71b are arranged in parallel with the direction of travel of the cutting line 1b. The opposing surface 71as and the opposing surface 71bs are, for example, vertical surfaces.

[0059] The machining fluid rectifying plate 71a is the first machining fluid rectifying plate among the pair of machining fluid rectifying plates 71, and is connected to the machining power source 5. Therefore, the electric discharge machining power source is supplied to the workpiece W, the workpiece power supply auxiliary portion 73, and the thin plate side surface holding portions 75a, 75b via the machining fluid rectifying plate 71a from the machining power source 5. Thus, the electric discharge machining power source can be supplied to the workpiece W not only from the machining fluid rectifying plate 71a in contact with the end surface of the workpiece W, but also from the workpiece power supply auxiliary portion 73 and the thin plate side surface holding portions 75a, 75b in contact with the machining fluid rectifying plate 71a.

[0060] The machining liquid rectifying plate 71b is the second machining liquid rectifying plate among the pair of machining liquid rectifying plates 71, and is arranged parallel to the machining liquid rectifying plate 71a in a state where the workpiece W fixed to the machining liquid rectifying plate 71a, the workpiece power supply auxiliary portion 73, and the thin plate side surface holding portions 75a, 75b are sandwiched between the machining liquid rectifying plate 71a. That is, the workpiece W fixed to the machining liquid rectifying plate 71a, the workpiece power supply auxiliary portion 73, and the thin plate side surface holding portions 75a, 75b are sandwiched between the opposing surface 71as of the machining liquid rectifying plate 71a and the opposing surface 71bs of the machining liquid rectifying plate 71b, which are arranged in parallel.

[0061] The machining liquid rectifying plate 71b is in close contact with the workpiece W, and forms a flow path for guiding the machining liquid supplied from the nozzles 7a and 7b to the workpiece W together with the machining liquid rectifying plate 71a. The machining liquid is supplied from the nozzles 7a and 7b to the gap between the machining liquid rectifying plate 71a and the machining liquid rectifying plate 71b toward the workpiece W. The machining liquid ejected from the plurality of machining liquid ejection holes 7c of the nozzles 7a and 7b is guided to the workpiece W through the opposing surface 71as of the machining liquid rectifying plate 71a and the opposing surface 71bs of the machining liquid rectifying plate 71b. That is, the opposing surface 71as of the machining liquid rectifying plate 71a and the opposing surface 71bs of the machining liquid rectifying plate 71b restrict the flow of the machining liquid supplied to the gap between the machining liquid rectifying plate 71a and the machining liquid rectifying plate 71b in the x-axis direction, and form a flow path for guiding the flow of the machining liquid to the workpiece W.

[0062] Thus, the machining fluid is prevented from diffusing in the thickness direction of the thin plate during forming, that is, in the x-axis direction. In addition, the cutting line portion 1b is inserted and penetrated through the plurality of machining fluid ejection holes 7c of the nozzles 7a and 7b. Thus, the machining fluid easily enters the gap between the cutting line portion 1b and the workpiece W.

[0063] In the in-line electrical discharge machining device 1000, the machining fluid supplied from the nozzles 7a and 7b is rectified as described above, so that the diffusion of the machining fluid is suppressed, and the risk of the thin plate being broken due to the oscillation of the machining fluid during formation is reduced.

[0064] The workpiece W is fixed inside the thin plate machining stabilizing portion 70 while being clamped between the machining liquid rectifying plate 71a and the machining liquid rectifying plate 71b. That is, the workpiece W is fixed to the opposing surface 71as of the machining liquid rectifying plate 71a while being clamped between the opposing surface 71as of the machining liquid rectifying plate 71a and the opposing surface 71bs of the machining liquid rectifying plate 71b. One end surface of the cylindrical shape of the workpiece W is fixed to the opposing surface 71as of the machining liquid rectifying plate 71a while the axial direction of the cylindrical shape is perpendicular to the opposing surface 71as of the machining liquid rectifying plate 71a and the opposing surface 71bs of the machining liquid rectifying plate 71b. In addition, the other end surface of the cylindrical shape of the workpiece W is in close contact with the opposing surface 71bs of the machining liquid rectifying plate 71b.

[0065] When the workpiece W is a material for semiconductor wafers, the shape of the workpiece W is often pre-formed into a cylindrical shape so that the thin plate processed by cutting becomes a circular thin plate. Here, the cylindrical side surface constituting the curved surface of the cylindrical workpiece W is recorded as the outer peripheral side surface. In addition, the workpiece W is arranged in the thin plate processing stabilizing portion 70 in such a manner that the outer peripheral side surface is opposite to the cutting line portion 1b. The workpiece W is wheel-cut by the cutting line portion 1b, thereby processing a wafer as a thin plate from the workpiece W.

[0066] In the discharge cutting process in which the workpiece W is cut by the cutting line portion 1b, the portion of the workpiece W where the cutting process starts by the cutting line portion 1b is defined as the cutting start portion. In addition, in the discharge cutting process in which the workpiece W is cut by the cutting line portion 1b, the portion of the workpiece W where the cutting process by the cutting line portion 1b ends is defined as the processing end portion.

[0067] The cutting line portion 1b is repeatedly wound at predetermined intervals, and passes between the machining fluid rectifying plate 71b and the machining fluid rectifying plate 71a which are parallel to each other and face each other with the workpiece W fixed to the machining fluid rectifying plate 71a interposed therebetween.

[0068] By changing the posture to a state where the machining liquid rectifying plate 71a and the machining liquid rectifying plate 71b to which the workpiece W is fixed are relatively rotated with respect to the cutting line portion 1b, or relatively tilted, and provided on a posture changing mechanism (not shown) to be fixed, a plurality of thin plates having a cut surface that forms a specific angle with respect to the reference surface when the opposing surface 71as of the machining liquid rectifying plate 71a is set as the reference surface can be simultaneously cut out from the workpiece W. In addition, as a mechanism for rotating or tilting the workpiece W, a rotating table and an angle measuring table can be used.

[0069] like Figure 3As shown, the workpiece power supply auxiliary part 73 is fixed to the machining fluid rectifying plate 71a in a state where the machining end portion of the workpiece W is in contact with the outer peripheral side surface of the workpiece W. In addition, in the area from the diameter portion of the workpiece W to the cutting start portion, the workpiece pressing part 72 is fixed to the machining fluid rectifying plate 71a in a state where it is in contact with the outer peripheral side surface of the workpiece W. Figure 3 In the embodiment, a workpiece pressing portion 72 is provided along the outer peripheral side surface of the cut workpiece W.

[0070] The diameter portion is a portion of the workpiece W having a cylindrical shape whose cutting length changes according to the cutting position of the workpiece W in the z-axis direction, and becomes the maximum cutting length. In the cutting process of the workpiece W, the cutting length is the cutting length formed by the cutting line portion 1b in the cutting process in the horizontal direction, that is, the y-axis direction.

[0071] The workpiece power supply auxiliary part 73 contacts the outer peripheral side of the workpiece W from below the workpiece W, and holds and fixes the workpiece W. In addition, the workpiece power supply auxiliary part 73 constitutes a power supply path from the machining liquid rectifying plate 71a to the workpiece W. The workpiece power supply auxiliary part 73 is fixed to the machining liquid rectifying plate 71a in a state where the outer peripheral side of the workpiece power supply auxiliary part 73 contacts the outer peripheral side of the lowermost part of the workpiece W. That is, the workpiece power supply auxiliary part 73 is fixed to the machining liquid rectifying plate 71a in a state where the outer peripheral side of the workpiece power supply auxiliary part 73 contacts the outer peripheral side of the lowermost part of the workpiece W. In other words, the workpiece power supply auxiliary part 73 contacts the outer peripheral side of the part of the workpiece W where the cutting process by the cutting line part 1b ends, that is, the processing terminal part.

[0072] An example of the shape of the workpiece power supply auxiliary part 73 is a cylindrical shape. The workpiece power supply auxiliary part 73 having a cylindrical shape has one end surface of the cylindrical shape fixed to the opposite surface 71as of the machining liquid rectifying plate 71a in a state where the axial direction of the cylindrical shape is perpendicular to the opposite surface 71as of the machining liquid rectifying plate 71a. The height of the workpiece power supply auxiliary part 73 from the opposite surface 71as as the installation surface in the machining liquid rectifying plate 71a is set to be less than or equal to the thickness of the workpiece W. The thickness of the workpiece W is the length of the cylindrical shape in the workpiece W in the axial direction. In addition, the shape of the workpiece power supply auxiliary part 73 is not limited to a cylindrical shape.

[0073] The workpiece power supply auxiliary portion 73 described above can be referred to as a lower workpiece holding portion that contacts the workpiece W from below to hold the workpiece W and has conductivity.

[0074] The thin plate side surface holding parts 75a and 75b contact the outer peripheral side surface of the workpiece W from below the workpiece W, and hold and fix the workpiece W. In addition, the thin plate side surface holding parts 75a and 75b constitute a power supply path from the machining liquid rectifying plate 71a to the workpiece W. The thin plate side surface holding parts 75a and 75b are arranged at positions below the diameter portion of the cylindrical workpiece W on the opposing surface 71as of the machining liquid rectifying plate 71a, at positions symmetrical with respect to the workpiece power supply auxiliary part 73, and at positions contacting the outer peripheral side surface of the workpiece W above the position where the cutting of the workpiece W is completed.

[0075] An example of the shape of the thin plate side holding parts 75a, 75b is a cylindrical shape. The thin plate side holding parts 75a, 75b having a cylindrical shape are fixed to the opposite surface 71as of the machining liquid rectifying plate 71a in a state where the axial direction of each cylindrical shape is perpendicular to the opposite surface 71as of the machining liquid rectifying plate 71a. The height of the thin plate side holding parts 75a, 75b from the opposite surface 71as of the machining liquid rectifying plate 71a as the installation surface is set to be less than or equal to the thickness of the workpiece W. The thickness of the workpiece W is the length of the cylindrical shape in the workpiece W in the axial direction. In addition, the shape of the thin plate side holding parts 75a, 75b is not limited to a cylindrical shape.

[0076] The thin plate side holding parts 75a and 75b as described above can be said to be lower workpiece holding parts, which are in contact with the workpiece W from below to hold the workpiece W and have conductivity. Moreover, the thin plate side holding parts 75a and 75b are cut together with the workpiece W as described later, and the plurality of thin plate parts of the thin plate side holding parts 75a and 75b formed by cutting the thin plate side holding parts 75a and 75b support and fix the plurality of thin plates that are formed by cutting the workpiece W at the same time as the thin plate parts and are separated from each other.

[0077] The workpiece pressing portion 72 presses the multiple thin plates in the process of being formed from the outer peripheral side of the cutting start portion side of the multiple thin plates, and fixes the multiple thin plates in the process of being formed together. The workpiece pressing portion 72 fixes the multiple thin plates in the process of being formed together, thereby suppressing the swing of the multiple thin plates caused by the vibration of the workpiece W caused by the hydraulic pressure of the machining fluid flow on the cut surface of the multiple thin plates. The workpiece pressing portion 72 has a rectangular parallelepiped shape formed with a groove portion 72a, and the groove portion 72a accommodates a part of the workpiece W on the cutting start portion side. In addition, the shape of the workpiece pressing portion 72 is not limited to a rectangular parallelepiped shape.

[0078] The workpiece pressing portion 72 is not provided at the time of starting the discharge cutting process of the workpiece W. The workpiece pressing portion 72 performs the discharge cutting process after the start of the discharge cutting process of the workpiece W. When the discharge cutting process performed by the cutting line portion 1b reaches a position that is greater than or equal to 1 / 6 and less than or equal to 1 / 5 of the cutting distance of the workpiece W, the contact portion of the workpiece pressing portion 72 presses and contacts the workpiece W and the upper portion of each thin plate from above the workpiece W and the multiple thin plates in the process. The workpiece pressing portion 72 is inserted from above the workpiece W and the multiple thin plates into the space sandwiched by the pair of machining liquid rectifying plates 71a and 71b. The workpiece pressing portion 72 is automatically arranged on the upper portion of the multiple thin plates in the process of forming by the workpiece pressing portion holding device 78.

[0079] The cutting distance is the distance from the cutting start portion to the processing end portion of the workpiece W, and corresponds to the diameter of the workpiece W.

[0080] The object pressing portion holding device 78 is controlled by the control unit 300, and automatically arranges the object pressing portion 72 on the upper part of the multiple thin plates formed in the middle at a predetermined timing. In addition, the object pressing portion holding device 78 makes the object pressing portion 72 retreat from the upper part of the multiple thin plates after cutting at the timing when the cutting process of the object W is finished according to the control of the control unit 300. The object pressing portion 72 is held in the height direction by the object pressing portion holding device 78. At the beginning of the cutting process, the object pressing portion 72 is held in the initial cutting position separated upward from the object W and the cutting line portion 1b. After the start of the cutting process, the object pressing portion 72 fixes the thin plate gradually processed from the object W into a thin plate shape. In addition, the force of pressing the object pressing portion 72 to the thin plate can be obtained by a driving device such as a motor or a cylinder, or by using a heavy object.

[0081] The contact portion of the workpiece pressing portion 72 is a portion where the workpiece pressing portion 72 contacts the upper portion of the workpiece W, that is, the upper portion of the plurality of thin plates. The contact portion of the workpiece pressing portion 72 is formed into a shape along the outer peripheral side of the workpiece W, that is, along the outer peripheral side of the plurality of thin plates. That is, when the shape of the workpiece W is a cylindrical shape, the contact portion of the workpiece pressing portion 72 is formed into a shape along the outer peripheral side of the cylindrical shape, that is, an arc shape.

[0082] In addition, a thin plate portion pressing portion 76 is installed at the contact portion of the workpiece pressing portion 72. The thin plate portion pressing portion 76 presses the workpiece W from above and fixes the multiple thin plates that are in the process of being formed. That is, the thin plate portion pressing portion 76 presses the multiple thin plates that are in the process of being formed from the outer peripheral side surface of the cutting start portion side of the multiple thin plates and fixes the multiple thin plates that are in the process of being formed. The thin plate portion pressing portion 76 increases the contact area between the contact portion of the workpiece pressing portion 72 and the workpiece W, that is, the contact area between the contact portion of the workpiece pressing portion 72 and the outer peripheral side surface of the multiple thin plates, and fixes the multiple thin plates that are in the process of being formed. The thin plate pressing portion 76 fixes multiple thin plates that are being formed together, thereby increasing the contact area between the contact portion of the workpiece pressing portion 72 and the outer peripheral side surfaces of the multiple thin plates, and suppressing the swing of the multiple thin plates caused by the vibration of the workpiece W due to the hydraulic pressure of the machining fluid flow applied to the cut surfaces of the multiple thin plates.

[0083] When the workpiece pressing portion 72 pushes the workpiece pressing portion 76 to the outer peripheral side of the workpiece W, that is, the outer peripheral side of the plurality of thin plates, the thin plate pressing portion 76 is deformed between the contact portion of the workpiece pressing portion 72 and the outer peripheral side of the workpiece W. A portion of the deformed thin plate pressing portion 76 enters into the plurality of machining grooves formed between the plurality of thin plates. Thus, in the in-line electrical discharge machining device 1000, the intervals between the plurality of thin plates cut out from the workpiece W are maintained by the deformed thin plate pressing portion 76, so that the risk of the thin plates being broken due to the swing of the machining fluid is reduced.

[0084] In addition, the other part of the deformed thin plate portion pressing portion 76 does not enter the inside of the processing groove, and is clamped between the contact portion of the workpiece pressing portion 72 and the outer peripheral side of each thin plate in a state where the unevenness of the contact portion of the workpiece pressing portion 72 and the unevenness of the outer peripheral side of each thin plate are buried. As a result, in the in-line EDM device 1000, the contact area between the contact portion of the workpiece pressing portion 72 and the outer peripheral side of each thin plate through the thin plate portion pressing portion 76 is expanded, and the force for holding the outer peripheral side of a plurality of thin plates cut from the workpiece W in the process of forming is strengthened from above the workpiece W.

[0085] Therefore, when the workpiece pressing portion 72 is pushed to the peripheral side of the workpiece W, that is, the peripheral side of the multiple thin plates, the thin plate pressing portion 76 is deformed, and the multiple thin plates formed in the middle are held from the thickness direction of the thin plates. In addition, the peripheral side of the multiple thin plates formed in the middle is held from above the workpiece W, thereby preventing the thin plates formed in the middle from being broken due to the swinging of the machining fluid.

[0086] When fixing the workpiece W to the machining fluid rectifying plate 71a, a conductive adhesive, conductive sheet, conductive adhesive tape, low melting point metal, conductive wax, etc. having conductivity is used. When fixing the workpiece W to the machining fluid rectifying plate 71a, a conductive material is used, so that the workpiece W and the machining fluid rectifying plate 71a are electrically connected. As described later, the power supply for electric discharge machining from the machining power supply 5 to the workpiece W can be realized via the machining fluid rectifying plate 71a.

[0087] In addition, when fixing the workpiece power supply auxiliary part 73 and the thin plate side holding parts 75a, 75b to the machining fluid rectifying plate 71a, in addition to conductive adhesives, conductive sheets, conductive adhesive tapes, low melting point metals, and conductive wax, screw fastening using metal threads is used. When fixing the workpiece power supply auxiliary part 73 and the thin plate side holding parts 75a, 75b to the machining fluid rectifying plate 71a, a conductive material is used, thereby conducting between the workpiece power supply auxiliary part 73 and the thin plate side holding parts 75a, 75b and the machining fluid rectifying plate 71a. As a result, as described later, power supply from the machining power supply 5 to the workpiece W for electric discharge machining can be achieved via the machining fluid rectifying plate 71a and the workpiece power supply auxiliary part 73. In addition, power supply from the machining power supply 5 to the workpiece W for electric discharge machining can be achieved via the machining fluid rectifying plate 71a and the thin plate side holding parts 75a, 75b.

[0088] Figure 4 1 is a diagram showing a power supply path of the electric discharge machining power supply from the machining power supply 5 to the workpiece W in the wire electric discharge machining device 1000 according to the first embodiment. In the wire electric discharge machining device 1000, the electric discharge machining power supply supplies power to the workpiece W from the machining power supply 5 via the machining fluid rectifying plate 71a. In addition, the electric discharge machining power supply supplies power to the workpiece W from the machining power supply 5 via the machining fluid rectifying plate 71a and the workpiece power supply auxiliary portion 73. In addition, the electric discharge machining power supply supplies power to the workpiece W from the machining power supply 5 via the machining fluid rectifying plate 71a and the thin plate side surface holding portion 75a. In addition, the electric discharge machining power supply supplies power to the workpiece W from the machining power supply 5 via the machining fluid rectifying plate 71a and the thin plate side surface holding portion 75b.

[0089] The control unit 300 controls the entire wire electrical discharge machining device 1000 . Figure 51 is a block diagram showing a configuration example of a control unit 300 included in the wire electrical discharge machining device 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 portion holding control device 36. The control unit 300 controls the wire electrical discharge machining device 1000.

[0090] The processing state acquisition unit 33 acquires various processing state information ps including the position of the workpiece W in the z-axis direction from the output of various sensors, and outputs the acquired processing state information ps to the processing control device 31. The processing 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 processing state information ps. The discharge waveform control device 32 controls the processing power supply 5 based on the discharge waveform command wc input from the processing control device 31, and controls the voltage waveform applied to the inter-electrode or the current waveform flowing between the electrodes.

[0091] The wire travel control device 35 drives and controls the wire shaft rotation control devices 8a and 8b based on the wire electrode travel command rc input from the processing control device 31, and controls the travel of the wire electrode 1. In addition, the wire travel control device 35 drives and controls the traverse control devices 9a and 9b based on the wire electrode travel command rc input from the processing control device 31, and controls the traverse control.

[0092] The cutting table drive control device 34 drives the cutting feed table 10 based on the cutting table instruction sc input from the processing control device 31 to control the relative position between the workpiece W and the cutting line portion 1b. In addition, the cutting table drive control device 34 also sends the cutting table instruction sc to the workpiece pressing portion holding control device 36 connected to the workpiece pressing portion holding device 78.

[0093] The workpiece pressing portion holding control device 36 monitors the coordinate value of the cutting feed table 10 in the z-axis direction based on the cutting table instruction sc from the cutting table drive control device 34, and drives and controls the workpiece pressing portion holding device 78 through the pressing portion holding control instruction qc when the cutting feed table 10 reaches the preset first position, and controls the placement of the workpiece pressing portion 72 to the upper part of the multiple thin plates in the process of being formed. In addition, the workpiece pressing portion holding control device 36 monitors the coordinate value of the cutting feed table 10 in the z-axis direction based on the cutting table instruction sc from the cutting table drive control device 34, and drives and controls the workpiece pressing portion holding device 78 through the pressing portion holding control instruction qc when the cutting feed table 10 reaches the preset second position, and controls the workpiece pressing portion 72 to retreat from the upper part of the multiple thin plates after cutting.

[0094] Figure 6 This is a flowchart showing the operation of the wire electrical discharge machining device 1000 according to the first embodiment during cutting processing. Figure 7 It is a first perspective view showing a state of the thin plate processing stabilizing section 70 included in the wire electrical discharge machining apparatus 1000 according to the first embodiment during the cutting process of the thin plate. Figure 8 It is a second perspective view showing a state of the thin plate processing stabilizing section 70 included in the wire electrical discharge machining apparatus 1000 according to the first embodiment during the cutting process of the thin plate.

[0095] exist Figure 7 , the state in which the workpiece W is cut from the outer peripheral side of the workpiece W at the cutting start side, that is, from the outer peripheral side of the upper side of the workpiece W to a position of about 1 / 6 in the height direction is shown. Figure 8 In the figure, it is shown that Figure 7 From the state shown, the cutting process is further carried out, and the workpiece pressing portion 72 contacts the outer peripheral side of the workpiece W on the side of the cutting start portion, that is, the outer peripheral side of the upper side of the plurality of thin plates, and the workpiece pressing portion 72 is used to hold the plurality of thin plates in the process of forming. Figure 8 , the cutting line portion 1b is shown to extend downward in the z-axis direction beyond the central axis C of the workpiece W, and the thin plate side holding portions 75a and 75b fixed to the outer peripheral side of the workpiece W are also cut by the cutting line portion 1b and the workpiece W at the same time. Figure 7 In order to facilitate understanding, several components are shown in a state of being observed through. Next, the operation of the wire electrical discharge machining device 1000 during cutting processing will be described. In addition, the following operation is performed under the control of the control unit 300.

[0096] At the beginning of the cutting process, the workpiece W is fixed to the thin plate processing stabilizing portion 70. At the beginning of the cutting process, the workpiece W is separated from the cutting line portion 1b and is located directly below the cutting line portion 1b. In addition, at the beginning of the cutting process, the workpiece pressing portion 72 is not provided. In this state, the cutting line portion 1b starts to move forward. The cutting line portion 1b passes through the plurality of machining fluid ejection holes 7c of the nozzles 7a and 7b, and moves directly above the workpiece W sandwiched between the machining fluid rectifying plate 71a and the machining fluid rectifying plate 71b.

[0097] In addition, the power for electric discharge machining is supplied from the machining power source 5 to the workpiece W via the machining fluid rectifying plate 71a. In addition, the power for electric discharge machining is supplied from the machining fluid rectifying plate 71a to the workpiece W via the machining power supply auxiliary portion 73, the thin plate side holding portion 75a, and the thin plate side holding portion 75b. In addition, the power for electric discharge machining is supplied from the machining power source 5 to the cutting line portion 1b via the power supply units 6a and 6b. In addition, the machining fluid is supplied from the nozzles 7a and 7b to the gap between the machining fluid rectifying plate 71a and the machining fluid rectifying plate 71b.

[0098] When the cutting process starts, the control unit 300 raises the cutting feed table 10 to change the relative position between the workpiece W and the cutting line portion 1b. Specifically, the control unit 300 raises the cutting feed table 10 to move upward the thin plate processing stabilizing portion 70 on which the workpiece W is fixed. As a result, the workpiece W disposed on the thin plate processing stabilizing portion 70 is relatively close to and in contact with the cutting line portion 1b, and is cut by the cutting line portion 1b.

[0099] In addition, if the cutting process is started, a machining fluid rectifying process is performed in step S110. In the machining fluid rectifying process, the machining fluid supplied from the nozzles 7a and 7b to the thin plate machining stabilizing portion 70 is rectified and collides with the workpiece W. The machining fluid supplied from the nozzles 7a and 7b to the thin plate machining stabilizing portion 70 collides with the workpiece W after the flow in the x-axis direction is restricted by the machining fluid rectifying plates 71a and 71b inside the thin plate machining stabilizing portion 70. That is, the opposing surfaces 71as of the machining fluid rectifying plates 71a and the opposing surfaces 71bs of the machining fluid rectifying plates 71b restrict the flow of the machining fluid supplied to the gap between the machining fluid rectifying plates 71a and 71b in the x-axis direction, and guide the flow of the machining fluid to the workpiece W.

[0100] Therefore, the machining fluid rectification process can be said to be the following process, that is, the machining fluid is sprayed from the nozzles 7a and 7b toward the space sandwiched by a pair of machining fluid rectifying plates 71, the flow of the machining fluid is guided toward the workpiece W through the relative surfaces 71as and 71bs of the pair of machining fluid rectifying plates 71, and the machining fluid is supplied to the gaps between the multiple cutting line portions 1b and the workpiece W.

[0101] As described above, the control unit 300 controls each unit of the wire electrical discharge machining device 1000 to perform electrical discharge cutting machining of the workpiece W. The machining fluid rectifying step of step S110 is continuously performed from the start of the cutting machining to the end of the cutting machining.

[0102] Then, in step S120, a wafer pressing process is performed. In the wafer pressing process, the electrical discharge cutting process is performed, and at the time when the electrical discharge cutting process performed by the cutting line portion 1b is performed to a position of about 1 / 6 or more and 1 / 5 or less of the cutting distance of the workpiece W, the contact portion of the workpiece pressing portion 72 is pressed and contacted with the workpiece W and the upper portion of each thin plate from above the workpiece W and the plurality of thin plates in the process.

[0103] Thus, the thin plate portion pressing portion 76 installed at the contact portion of the workpiece pressing portion 72 presses the workpiece W from above and fixes the multiple thin plates in the process of being formed. That is, the thin plate portion pressing portion 76 presses the multiple thin plates in the process of being formed from the outer peripheral side surface of the cutting start portion side of the multiple thin plates and fixes the multiple thin plates in the process of being formed. The thin plate portion pressing portion 76 fixes the multiple thin plates in the process of being formed, thereby suppressing the swing of the multiple thin plates caused by the vibration of the workpiece W caused by the hydraulic pressure of the machining fluid flow on the cut surfaces of the multiple thin plates.

[0104] Furthermore, as described above, the workpiece W is subjected to the electrical discharge cutting process while the plurality of thin plates being formed are fixed together by the workpiece pressing portion 72. Here, the plurality of thin plates machined from the workpiece W are held by the thin plate side holding portions 75a and 75b in contact with the outer peripheral side surfaces of the plurality of thin plates, so that the pressure generated by the machining fluid supplied from the nozzles 7a and 7b toward the machining groove Wg in the process of forming does not cause swinging or bending, thereby suppressing the change in the gap in the x-axis direction between the adjacent thin plates. As a result, the supply state of the machining fluid to the inside of the machining groove formed between the adjacent thin plates does not change, and the machining chips generated by the electrical discharge cutting process are stably discharged from the gap between the workpiece W and the cutting line portion 1b, i.e., the inter-electrode gap, and the cutting line portion 1b is stably cooled. Thus, the wire electrical discharge machining device 1000 can stably continue the wire electrical discharge cutting process of the workpiece W.

[0105] Therefore, the wafer pressing step can be said to be a step of holding the workpiece W cut in the cutting process from above the workpiece W and the plurality of cutting line portions 1 b.

[0106] Then, in step S130, the wafer support process is performed. Further, the discharge cutting process is performed. If the cutting line portion 1b is hung on the thin plate side holding portions 75a and 75b in the z-axis direction, Figure 8 As shown, the thin plate side surface holding portions 75a, 75b are simultaneously subjected to electric discharge cutting processing from above along the cutting line portion 1b together with the workpiece W.

[0107] In the wafer support process, during the cutting process of the workpiece W, the workpiece holding portion, i.e., the workpiece power supply auxiliary portion 73 and the thin plate side surface holding portions 75a and 75b, which are provided in the cutting process direction over the upper and lower regions of the part of the workpiece W where the cutting process is completed, i.e., the processing terminal portion, and are fixed to the facing surface 71as of one of the pair of working liquid rectifying plates 71, i.e., the working liquid rectifying plate 71a, and have conductivity, come into contact with the workpiece W from below to hold the workpiece W. In addition, in this state, from the start of the cutting process of the workpiece W to the end of the cutting process of the workpiece W, the workpiece W is powered from the working liquid rectifying plate 71a via the workpiece power supply auxiliary portion 73 and the thin plate side surface holding portions 75a and 75b as the lower workpiece holding portion.

[0108] If the discharge cutting process is performed, the cutting line portion 1b is hung on the thin plate side holding portions 75a and 75b in the z-axis direction. Figure 8 As shown, the thin plate side holding parts 75a, 75b are simultaneously subjected to discharge cutting processing by the cutting line part 1b from the upper side with the workpiece W. In this state, until the cutting processing of the workpiece W is completed, the workpiece W is powered from the machining fluid rectifying plate 71a via the workpiece power supply auxiliary part 73 as the lower workpiece holding part and the thin plate side holding parts 75a, 75b.

[0109] Furthermore, the thin plate side holding parts 75a and 75b are arranged so that the lowest part of each is located below the lowest part of the workpiece W. Therefore, since the thin plate side holding parts 75a and 75b are cut and separated into a plurality of thin plates in the middle of processing the workpiece W, the holding force of the thin plate side holding parts 75a and 75b for the plurality of thin plates processed from the workpiece W is not lost. That is, at the moment when the discharge cutting processing for the workpiece W is completed, a plurality of thin plate parts 75c having the same width as the thin plates formed from the workpiece W and the same number as the thin plates formed from the workpiece W are formed on the thin plate side holding parts 75a and 75b.

[0110] However, the plurality of thin plate portions 75c formed by the thin plate side holding portions 75a and 75b are not separated from the workpiece W. Therefore, in a state where the discharge cutting process of the plurality of thin plates from the workpiece W is completed, the plurality of thin plates processed from the workpiece W are continuously held by the thin plate portions 75c formed by the thin plate side holding portions 75a and 75b and the workpiece pressing portion 72.

[0111] Fig. 9 This is a diagram for explaining the relationship between the cutting position and the cutting length of the workpiece W during the cutting process by the wire electrical discharge machining device 1000 according to the first embodiment. Fig. 9 The left figure shows an example of the positional relationship among the workpiece W, the workpiece power supply auxiliary portion 73, and the thin plate side surface holding portions 75a and 75b in the in-plane direction of the opposing surface 71as of the machining fluid rectifying plate 71a. Fig. 9 The figure on the right shows the Fig. 9 The cutting length at the cutting position of the workpiece W in the left figure. Fig. 9 The solid line in the right figure shows the cutting processing length in the cutting processing of the workpiece W performed by the wire electrical discharge machining device 1000. Fig. 9 The dotted line in the right figure shows the cutting length of the workpiece W in the cutting process when the thin plate side surface holding parts 75a and 75b are not provided in the structure of the wire electric discharge machining device 1000. Fig. 9 The dashed line in the right figure shows the cutting length when only the thin plate side surface holding portions 75a and 75b are cut by the wire electrical discharge machining device 1000.

[0112] In the cutting process of the cylindrical workpiece W by the wire electrical discharge machining device 1000 , the cutting length varies according to the cutting position in the height direction during the cutting process, that is, according to the cutting position in the z-axis direction during the cutting process.

[0113] like Fig. 9 As shown by the solid line in the right figure of , when the cutting process is performed from the processing start position PS of the workpiece W, that is, the uppermost end of the workpiece W, toward the processing end position PE of the workpiece W, that is, the lowermost end of the workpiece W, in the processing section of the workpiece W, the cutting process length changes corresponding to the cutting position of the workpiece W in the height direction, and the cutting process length becomes the maximum at the diameter part position PD of the workpiece W. The cutting process is further continued, and after the cutting line portion 1b passes the diameter part position PD of the workpiece W in the height direction, the cutting process length is continuously reduced as the cutting process proceeds.

[0114] The cutting process is further performed. At the processing position PH, if the cutting line portion 1b is hung on the thin plate side holding portions 75a and 75b in the z-axis direction, the thin plate side holding portions 75a and 75b are cut from the upper side by the cutting line portion 1b simultaneously with the workpiece W. From this moment on, the cutting process length becomes the total cutting process length of the workpiece W and the cutting process length of the thin plate side holding portions 75a and 75b, and as the cutting process proceeds, it temporarily increases and then decreases. That is, in the wire discharge machining device 1000, the thin plate side holding portions 75a and 75b are cut together with the workpiece W, thereby easing the sharp decrease in the cutting process length near the processing end portion.

[0115] like Fig. 9 As shown by the dotted line in the right figure of , if the thin plate side retaining parts 75a and 75b are not configured in the structure of the online EDM device 1000, the cutting processing length will decrease relative to the change of the cutting position if it passes through the processing position PH, and will decrease sharply near the processing end. The sharp decrease in the cutting processing length is one of the reasons for the sharp change in the state of the online EDM. When the state of the online EDM changes sharply, the risk of wire breakage increases. In addition, if the state of the online EDM changes sharply, if the appropriate processing conditions of the thin plate are not selected in response to the change in the cutting processing length, the plate thickness in the cut surface of the processed thin plate fluctuates, which has an adverse effect on the quality of the thin plate.

[0116] On the other hand, in the online EDM device 1000, the thin plate side holding parts 75a and 75b configured to hold a plurality of thin plates are cut together with the workpiece W, thereby relieving the sharp reduction in the cutting length near the processing end, and suppressing the occurrence of adverse effects on the cutting quality of the thin plate caused by the sharp change in the EDM state described above. In addition, in the online EDM device 1000, the thin plate side holding parts 75a and 75b are provided, thereby relieving the direct impact of the machining fluid flow supplied from the nozzles 7a and 7b on the thin plate, thereby suppressing the swing of the thin plate caused by the machining fluid flow, and preventing the occurrence of the thin plate breakage or thin plate loss that is easy to occur at the processing end of the thin plate.

[0117] Next, the configuration positions of the thin plate side holding parts 75a and 75b with respect to the workpiece W and the sizes of the thin plate side holding parts 75a and 75b are described. The thin plate side holding parts 75a and 75b are fixed to the machining liquid rectifying plate 71a in a state where the outer peripheral side of the thin plate side holding parts 75a and 75b is in contact with the outer peripheral side of the workpiece W. In addition, the contact position of the outer peripheral side of the thin plate side holding parts 75a and 75b with respect to the outer peripheral side of the workpiece W is located in the height direction, that is, in the cutting direction of the workpiece W, in the interval where the uncut length of the workpiece W in the cutting direction is less than or equal to 1 / 2 of the entire cut length of the workpiece W, and is located above the position where the outer peripheral side of the workpiece power supply auxiliary part 73 contacts the outer peripheral side of the workpiece W, that is, in the interval above the position where the cutting of the workpiece W is completed.

[0118] The uncut length in the cutting direction is the length of the uncut region of the workpiece W in the lower direction, that is, in the cutting direction as the z-axis lower direction. The entire cutting length of the workpiece W is the length of the diameter of the workpiece W having a cylindrical shape.

[0119] In addition, the width of the thin plate side surface holding parts 75a, 75b is the length that does not protrude from the machining liquid rectifying plates 71a, 71b in a state where the outer peripheral side surface of the thin plate side surface holding parts 75a, 75b is in contact with the outer peripheral side surface of the workpiece W. The width of the thin plate side surface holding parts 75a, 75b is the maximum length of the thin plate side surface holding parts 75a, 75b in the y-axis direction, that is, the maximum length of the thin plate side surface holding parts 75a, 75b in the advancing direction of the cutting line part 1b relative to the workpiece W. In addition, in a state where the workpiece W is completely cut and the cutting line part 1b passes through the workpiece W, there is an unprocessed portion in the thin plate side surface holding parts 75a, 75b.

[0120] As described above, the thin plate side surface holding portions 75a and 75b are made of a conductive material in order to realize the function of supplying power to the workpiece W. On the other hand, even if it is a conductive material, when there is a significant difference in physical properties such as resistance value or thermal conductivity between the material of the workpiece W and the material of the workpiece W, there will be a difference in discharge machining characteristics such as a difference in machining speed due to a difference in the ease of arc discharge or a difference in the degree of damage to the wire electrode 1 due to a difference in the wear characteristics of the wire electrode 1. As a result, in the area where the workpiece W and the thin plate side surface holding portions 75a and 75b are cut at the same time, the influence of the above-mentioned difference in discharge machining characteristics on the cutting process becomes significant, and it is expected that the discharge machining will become unstable.

[0121] Therefore, the material of the thin plate side retaining parts 75a, 75b is preferably a conductive material having the same electrical discharge machining characteristics as the workpiece W. For example, when the workpiece W composed of SiC is cut, the thin plate side retaining parts 75a, 75b produced by processing a sintered body of SiC powder can be used.

[0122] If the cutting process of the cylindrical workpiece W reaches the vicinity of the processing end portion of the workpiece W and is about to be cut and separated from the workpiece W, the flow rate of the machining fluid supplied from the nozzles 7a and 7b is adjusted to a flow rate that does not cause the wire electrode 1 of the cutting line portion 1b to break. As a result, the external force that causes the multiple thin plates to swing in the middle, that is, the hydraulic pressure of the machining fluid flow received by the cut surfaces of the multiple thin plates, is reduced. In this state, the cutting line portion 1b continues the cutting process while passing through the workpiece W, reaches the workpiece power supply auxiliary portion 73, and starts the cutting process of the workpiece power supply auxiliary portion 73 made of a material similar to the workpiece W. Then, if the control unit 300 determines that the cutting of the thin plate is completely completed based on the degree of progress of the cutting line portion 1b in the cutting process direction, the cutting process is stopped.

[0123] When the workpiece W is separated into a plurality of thin plates, the power supply path of the electric discharge machining power source from the machining fluid rectifying plate 71a to the workpiece W may be cut off depending on the separation status of the thin plates from the workpiece W. The workpiece power supply auxiliary portion 73 and the thin plate side holding portions 75a and 75b constitute the power supply path of the electric discharge machining power source to the workpiece W and the plurality of thin plates in the process of being formed from the start of the cutting process to the completion of the cutting process. Thus, the wire electric discharge machining device 1000 can stably continue the wire cutting process of the workpiece W.

[0124] In addition, if the power supply path of the electric discharge machining power supply to the cutting line portion 1b is disconnected before the cutting process is about to be completed, the cutting process is interrupted, resulting in a thin plate that has not been separated by passing through the remaining processed part that has not yet been cut, or a thin plate that has been broken at the boundary with the remaining processed part. In addition, the electric discharge machining gap in the cutting process direction, that is, the inter-electrode gap, is processed a small amount from the front end of the cutting line portion 1b. Therefore, the thin plate is cut and separated before the cutting line portion 1b completely passes through the workpiece W. As a result, at the processing end of the separated thin plate, the unprocessed part becomes a tiny residual protrusion and remains, which reduces the cutting process quality and yield rate of the thin plate.

[0125] On the other hand, the workpiece power supply auxiliary portion 73 is fixed at a position in contact with the lowermost end of the workpiece W in a state of contact with the workpiece W. Thus, the workpiece power supply auxiliary portion 73, together with the workpiece power supply pressing portion 72 and the thin plate side retaining portions 75a and 75b, can hold the multiple thin plates together with the external force that causes the multiple thin plates to swing before separation, thereby preventing the thin plates from being broken or missing.

[0126] In addition, the workpiece power supply auxiliary portion 73 and the thin plate side holding portions 75a and 75b constitute a power supply path for the electric discharge machining power supply to the workpiece W and the plurality of thin plates formed in the process from the start of the cutting process to the completion of the cutting process. As a result, the wire electric discharge machining device 1000 can stably continue the wire cutting process of the workpiece W. Therefore, in the wire electric discharge machining device 1000, the power supply path of the electric discharge machining power supply from the machining fluid rectifying plate 71a to the workpiece W is not disconnected according to the separation state of the thin plate from the workpiece W, and the generation of residual protrusions caused by the cutting line portion 1b not completely passing through the workpiece W due to the disconnection of the power supply path of the electric discharge machining power supply from the machining fluid rectifying plate 71a to the workpiece W can be prevented.

[0127] As described above, according to the wire discharge machining device 1000 involved in the first embodiment, discharge occurs between the plurality of advancing cutting wires and the workpiece, and the workpiece is subjected to discharge machining by the energy of the discharge, thereby simultaneously cutting off a plurality of wafers from the workpiece. The wire discharge machining device comprises: a wire electrode which is separated from each other in parallel and has a plurality of cutting wires facing the workpiece; a power supply unit which causes discharge to occur between the plurality of cutting wires and the workpiece; and a pair of machining fluid rectifying plates which are connected to a power supply, are provided in contact with both sides of the workpiece in a manner of sandwiching the workpiece, and have a conductive a pair of nozzles having a plurality of machining fluid ejection holes which are inserted through the plurality of cutting line portions and eject machining fluid toward a space sandwiched by a pair of machining fluid rectifying plates, and supply machining fluid to gaps between the plurality of cutting line portions and the workpiece; a cutting feed table which moves the pair of machining fluid rectifying plates up and down relative to the plurality of cutting line portions; a workpiece pressing portion which holds the workpiece separated during the cutting process from above the workpiece and the plurality of cutting line portions; and a lower workpiece holding portion which holds the workpiece by contacting the workpiece from below and having conductivity.

[0128] As described above, in the wire electric discharge machining device 1000 according to the first embodiment, a plurality of thin plates which are being separated from the workpiece W by the cutting process are held from the outer peripheral surface side of the workpiece W by the workpiece power supply auxiliary portion 73, the thin plate side holding portions 75a, 75b, and the workpiece pressing portion 72. Thus, in the wire electric discharge machining device 1000, the swing of the thin plate caused by the machining fluid flow supplied from the nozzles 7a, 7b can be suppressed or prevented, and the cracking of the thin plate, the loss of the thin plate, which is easy to occur at the processing end portion of the thin plate just before the cutting process is completed, and the generation of residual protrusions at the processing end portion of the thin plate caused by the residue of the processing end portion of the workpiece W at the end of the process can be prevented.

[0129] In addition, in the wire EDM device 1000, the above-mentioned structure is provided, so that when the cutting process is almost finished, it is not necessary to significantly suppress the flow rate of the machining fluid in order to reduce the external force on the thin plate caused by the collision of the machining fluid flowing to the thin plate, and the discharge of machining chips from the inter-electrode gap and the cooling state of the cutting wire portion 1b near the inter-electrode gap are not deteriorated. Therefore, in the wire EDM device 1000, it is possible to prevent a decrease in the machining speed due to poor discharge of machining chips or insufficient cooling of the cutting wire portion 1b, and it is possible to prevent the danger to the wire electrode 1 caused by a sudden change in the wire EDM state due to the significant suppression of the flow rate of the machining fluid.

[0130] Therefore, according to the wire electrical discharge machining device 1000 according to the first embodiment, there is an effect of being able to prevent damage to the thin plate when the thin plate is cut.

[0131] Implementation method 2.

[0132] Fig.10 FIG. 2 is a schematic diagram showing a configuration example of a workpiece power supply auxiliary unit 73 included in the wire electrical discharge machining device 1000a according to the second embodiment. Fig.10 , in the cutting process of the thin plate of the workpiece W in the wire EDM device 1000a, the cutting line 1b passes through the workpiece W and the cutting process of the thin plate from the workpiece W is completed, and the workpiece W is separated into a plurality of thin plates. Fig.10 In the embodiment, a conductive connection portion 77 is provided between the workpiece W and the workpiece power supply auxiliary portion 73 .

[0133] The wire EDM device 1000a according to the second embodiment is different from the wire EDM device 1000 according to the first embodiment in that a thin plate machining stabilizing portion 70a is provided instead of the thin plate machining stabilizing portion 70. The thin plate machining stabilizing portion 70a is different from the thin plate machining stabilizing portion 70 according to the first embodiment in that a conductive connecting portion 77 is provided. The other structures of the wire EDM device 1000a according to the second embodiment are the same as those of the wire EDM device 1000 according to the first embodiment, and repeated descriptions are omitted.

[0134] exist Fig.10 In the state shown, the thin plate side holding parts 75a and 75b are also formed with a plurality of processing grooves 75g formed by the cutting line part 1b. However, the thin plate side holding parts 75a and 75b are not separated into a plurality of thin plates. In addition, the plurality of thin plates processed from the workpiece W are held by the outer peripheral side surface of the thin plate part 75c formed on the thin plate side holding parts 75a and 75b and the workpiece pressing part 72. Fig.10 The workpiece pressing portion 72 is omitted in the figure.

[0135] like Fig.10 As shown, in the wire electric discharge machining device 1000a, a conductive connection portion 77 is interposed between the workpiece W and the workpiece power supply auxiliary portion 73. After the workpiece W is cut, the cutting process is continued, and the conductive connection portion 77 is cut by the cutting line portion 1b passing through the workpiece W, and a processing groove 77g is formed. The simultaneous cutting process of multiple thin plates by the cutting line portion 1b is determined by the control unit 300 as the completion of the thin plate cutting at the time when the processing groove 77g formed by all the wire electrodes 1 constituting the cutting line portion 1b is formed in the conductive connection portion 77, and the processing is completed.

[0136] When the workpiece W is made of SiC and the conductive connecting portion 77 is made of porous metal, the generation conditions of the discharge pulse or short-circuit pulse generated between the electrodes, the oscillation frequency of the discharge pulse generated between the electrodes, or the processing speed are significantly different between SiC and porous metal. Therefore, the determination of the completion of the cutting of the thin plate can be achieved by detecting the generation conditions of the discharge pulse when the state of the cutting process changes sharply, for example.

[0137] The conductive connection portion 77 is flexible and is disposed between the workpiece power supply auxiliary portion 73 and the workpiece W by being clamped, so as to electrically connect the workpiece power supply auxiliary portion 73 and the workpiece W. The conductive connection portion 77 fills the gap between the workpiece power supply auxiliary portion 73 and the workpiece W, thereby increasing the contact area between the workpiece power supply auxiliary portion 73 and the workpiece W relative to each other and the outer peripheral side surface, thereby improving the conductivity between the workpiece power supply auxiliary portion 73 and the workpiece W.

[0138] For the conductive connection part 77, a conductive material such as a low melting point metal or a porous metal is used, which has the characteristics of being soft and easy to deform. According to the easy deformation characteristics of the conductive connection part 77, the conductive connection part 77 pushed against the two peripheral sides of the outer peripheral side of the workpiece W and the outer peripheral side of the workpiece power supply auxiliary part 73 will be deformed. Moreover, the gap between the outer peripheral side of the workpiece W and the outer peripheral side of the workpiece power supply auxiliary part 73 is filled by the deformed conductive connection part 77. As a result, in the online electrical discharge machining device 1000a, the contact area between the workpiece power supply auxiliary part 73 and the workpiece W relative to each other and the peripheral side can be increased. Moreover, the contact area between the workpiece power supply auxiliary part 73 and the workpiece W relative to each other and the peripheral side is increased, thereby improving the conductivity between the workpiece power supply auxiliary part 73 and the workpiece W.

[0139] The material used for the conductive connection portion 77 is a conductive material having a Young's modulus of less than or equal to 80 GPa and a relative resistance of less than or equal to about 10 Ωcm, which can be deformed by pressure to fill the small gap between the workpiece W and the workpiece power supply auxiliary portion 73. An example of the size of the small gap is less than or equal to 100 μm and greater than or equal to about 300 μm. As an example, a porous sheet formed into a mesh shape by a metal such as nickel or cobalt can achieve deformation caused by bending or deformation in a compression direction due to the softness of the porous portion.

[0140] In addition, rubber or silicone rubber containing powder of a conductive substance such as silver or carbon and having a relative resistance value of 10 Ωcm or less can also be deformed by bending or in a compression direction.

[0141] In addition, it is difficult to obtain sufficient deformation of the adhesive tape formed by molding a conductive metal foil such as aluminum foil or copper foil. However, by laminating multiple sheets of aluminum foil or copper foil, for example, to form a laminated body with a thickness of about 1 mm, the laminated body can be used as the conductive connecting portion 77.

[0142] In addition, conductive wax mixed with carbon powder can also be used as the conductive connecting portion 77. The conductive wax mixed with carbon powder has good moldability, so it can be interposed between the workpiece W and the contact surface of the workpiece power supply auxiliary portion 73 to be worn, thereby filling the small gap between the workpiece W and the workpiece power supply auxiliary portion 73. The conductive wax melts at a temperature of about 40°C or more and about 60°C or less. Therefore, the conductive wax can be used by flowing into the small gap between the workpiece W and the workpiece power supply auxiliary portion 73 in a molten state.

[0143] The outer peripheral side surface of the workpiece W and the outer peripheral side surface of the workpiece power supply auxiliary part 73 are preferably completely in contact. However, in reality, it is difficult to set the workpiece W and the workpiece power supply auxiliary part 73 on the machining liquid rectifying plate 71 in a state where the outer peripheral side surface of the workpiece power supply auxiliary part 73 is completely in contact with the outer peripheral side surface of the workpiece W. That is, when the outer peripheral side surface of the workpiece W and the outer peripheral side surface of the workpiece power supply auxiliary part 73 are completely in contact, the parallelism of the outer peripheral side surfaces of the workpiece W and the workpiece power supply auxiliary part 73 that are in contact with each other are completely consistent, and the workpiece W and the workpiece power supply auxiliary part 73 need to be set on the machining liquid rectifying plate 71a in a state where the workpiece W and the workpiece power supply auxiliary part 73 are in close contact at the contact surface between the workpiece W and the workpiece power supply auxiliary part 73.

[0144] Here, the peripheral side surface of the workpiece W and the peripheral side surface of the workpiece power supply auxiliary part 73 are in complete contact, and the contact surface between the peripheral side surface of the workpiece W and the peripheral side surface of the workpiece power supply auxiliary part 73 is in uninterrupted and continuous contact in the y-axis direction, that is, in the axial direction of the workpiece W.

[0145] Fig.11 This is a conceptual diagram showing an example of a state immediately before the completion of the cutting process of a thin plate in the wire electrical discharge machining apparatus 1000 according to the first embodiment. Fig.12 Yes Fig.11 This is an enlarged view showing a specific area A in FIG. Fig.11 , a schematic diagram of a cross section at a position where the peripheral side surface Ws of the workpiece W and the peripheral side surface 73s of the workpiece power supply auxiliary part 73 contact each other just before the thin plate cutting process is completed is shown. The cross section at a position where the peripheral side surface Ws of the workpiece W and the peripheral side surface 73s of the workpiece power supply auxiliary part 73 contact each other is a cross section in the xz plane passing through the center axis C of the workpiece W. Fig.11 The arrow 83 in FIG. 8 shows the power supply path of the electric discharge machining power source from the machining fluid rectifying plate 71 a .

[0146] It is assumed that even if the peripheral side surface Ws of the workpiece W and the peripheral side surface 73s of the workpiece power supply auxiliary part 73 are polished and flattened with high precision, a small gap will be generated at the contact part as the butting part in the structure of making the peripheral side surfaces of the non-deformed rigid bodies butt each other. Therefore, it is considered difficult to make the non-deformed rigid bodies contact each other over the entire area of ​​the peripheral side surfaces. An example of the size of the small gap is greater than or equal to 10μm and less than or equal to about 50μm. In addition, depending on the accuracy of the straightness of the workpiece W and the workpiece power supply auxiliary part 73 relative to the setting surface of the machining liquid rectifying plate 71a on which the workpiece W and the workpiece power supply auxiliary part 73 are set and fixed, that is, the opposite surface 71as, a small gap of greater than or equal to 100μm and less than or equal to 300μm, which is larger than the wire diameter of the wire electrode 1 to be used, is sometimes generated.

[0147] If the workpiece power supply auxiliary part 73 contacts the workpiece W at a part, the electric discharge machining power supplied from the machining power supply 5 can be energized to the workpiece W. However, it is conceivable that before the cutting process of the plurality of thin plates formed from the workpiece W is completed, the power supply path of the electric discharge machining power supply from the machining power supply 5 via the machining fluid rectifying plate 71a and the workpiece power supply auxiliary part 73 is disconnected with respect to the thin plate portion separated from the workpiece W.

[0148] As described above, an example of a situation in which the power supply path of the electric discharge machining power source is disconnected is the following situation, namely, before the cutting process of multiple thin plates formed from the workpiece W is about to be completed, a small amount of processing is performed by the wire electrode 1 through a portion of the cutting wire portion 1b, or the remaining processed portion of the workpiece W that has not yet been cut becomes small, thereby reducing the mechanical strength of the remaining processed portion, and the thin plate in the middle of being formed is broken.

[0149] exist Fig.11 and Fig.12 In the state shown, just before the cutting process of the plurality of thin plates formed from the workpiece W is completed, the machining by the wire electrode 1 of the cutting wire portion 1b is performed a small amount in advance, and the power supply path of the electric discharge machining power source from the machining fluid rectifying plate 71a to the workpiece W is disconnected. On the other hand, the outer peripheral side surface 73s of the workpiece power supply auxiliary portion 73 and the outer peripheral side surface Ws of the workpiece W are in contact at a portion, so the power supply of the electric discharge machining power source to the workpiece W from the machining fluid rectifying plate 71a via the workpiece power supply auxiliary portion 73 continues.

[0150] If the power supply path of the power supply for the discharge machining is disconnected before the cutting of the multiple thin plates is about to be completed, the discharge machining is interrupted, resulting in a thin plate that passes through the remaining machining portion without being separated, or a thin plate that is broken at the boundary with the remaining machining portion. In addition, the discharge machining gap in the machining direction, that is, the inter-electrode gap, is processed a small amount from the front end of the cutting line portion 1b. Therefore, the thin plate is cut and separated before the cutting line portion 1b completely passes through the workpiece W. As a result, at the machining end of the separated thin plate, the unprocessed part becomes a tiny residual protrusion and remains, which reduces the cutting quality and yield rate of the thin plate.

[0151] Fig.13 This is a conceptual diagram showing an example of a state immediately before the completion of the cutting process of a thin plate in the wire electrical discharge machining device 1000 a according to the second embodiment. Fig.14 Yes Fig.13 The enlarged view is shown by enlarging a specific area B in FIG. Fig.13 , a schematic diagram of the cross section at the position where the peripheral side surface Ws of the workpiece W and the peripheral side surface 73s of the workpiece power supply auxiliary part 73 contact the conductive connecting part 77 is shown just before the thin plate cutting process is completed. The cross section at the position where the peripheral side surface Ws of the workpiece W and the peripheral side surface 73s of the workpiece power supply auxiliary part 73 contact the conductive connecting part 77 is a cross section in the xz plane passing through the central axis C of the workpiece W. Fig.13 The arrow 83 in FIG. 8 shows the power supply path of the electric discharge machining power source from the machining fluid rectifying plate 71 a .

[0152] exist Fig.13 In the figure, the conductive connecting part 77 arranged between the workpiece W and the workpiece power supply auxiliary part 73 is clamped between the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply auxiliary part 73, and is pushed to the outer peripheral side surface Ws of the workpiece W together with the workpiece power supply auxiliary part 73.

[0153] The conductive connection portion 77 is deformed by being pressed against the outer peripheral side surface Ws of the workpiece W, thereby filling the gap between the outer peripheral side surfaces of the workpiece power supply auxiliary portion 73 and the workpiece W. As a result, the contact area between the outer peripheral side surfaces of the workpiece power supply auxiliary portion 73 and the workpiece W is increased. As a result, in the wire discharge machining device 1000a, the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply auxiliary portion 73 can be completely in contact, and the conductivity between the workpiece power supply auxiliary portion 73 and the workpiece W is improved.

[0154] exist Fig.13 and Fig.14In the state shown, the peripheral side surface 73s of the workpiece power supply auxiliary portion 73 and the peripheral side surface Ws of the workpiece W are electrically connected via the conductive connecting portion 77. Therefore, after the cutting process of multiple thin plates formed from the workpiece W is completed, the power supply for discharge machining from the machining fluid rectifier plate 71a via the workpiece power supply auxiliary portion 73 and the conductive connecting portion 77 to the workpiece W will continue.

[0155] As described above, a material such as a low melting point metal or a porous metal, which has the characteristics of being soft and easily deformable, can be used for the conductive connecting portion 77. Due to the easy deformation characteristics of the conductive connecting portion 77, the conductive connecting portion 77 pushed against the two outer peripheral side surfaces, the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply auxiliary portion 73, is deformed. Moreover, the gap between the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply auxiliary portion 73 is filled by the deformed conductive connecting portion 77, and the contact area between the workpiece power supply auxiliary portion 73 and the workpiece W relative to each other and the outer peripheral side surface is expanded.

[0156] When the contact portion between the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply auxiliary portion 73 is not parallel to each other, the conductive connecting portion 77 is deformed, thereby merging the gap between the outer peripheral side surfaces of the workpiece power supply auxiliary portion 73 and the workpiece W, and the gap is blocked. In addition, even if there are minute irregularities in the contact portion between the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply auxiliary portion 73, the deformed conductive connecting portion 77 will fuse the gap between the outer peripheral side surfaces of the workpiece power supply auxiliary portion 73 and the workpiece W caused by the minute irregularities and block the gap.

[0157] Thus, in the wire EDM apparatus 1000a, the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply auxiliary portion 73 can be completely in contact, and the conductivity between the workpiece power supply auxiliary portion 73 and the workpiece W is improved. Moreover, the workpiece power supply auxiliary portion 73 and the conductive connecting portion 77 constitute a power supply path for the EDM power supply from the machining liquid rectifying plate 71a to the workpiece W and the plurality of thin plates being formed during the cutting process from the start of the cutting process to the completion of the cutting process. Thus, the wire EDM apparatus 1000a can stably continue the wire cutting process of the workpiece W.

[0158] Moreover, in the wire discharge machining device 1000a having the above-mentioned structure, in the cutting processing performed at multiple locations through the cutting wire portion 1b, it is possible to prevent the power supply path from the machining power supply 5 to the multiple thin plates formed in the middle from being disconnected, which occurs when the wire electrode 1 through a part of the cutting wire portion 1b cuts the workpiece W in a small amount and faster than the other wire electrodes 1 in the cutting wire portion 1b.

[0159] Therefore, in the wire EDM device 1000a, the wire electrode 1 constituting the cutting wire portion 1b does not interrupt the cutting process midway, and continues the cutting process while completely passing through the workpiece W to reach the conductive connection portion 77. As a result, the plurality of thin plates cut by the wire EDM device 1000a do not have a residual processing portion, i.e., a residual protrusion, at the processing end portion caused by the interruption of the cutting process, and the cutting process quality and yield rate are improved.

[0160] As described in the first embodiment, conductive wax can be used when fixing the workpiece W and the workpiece power supply auxiliary part 73 to the machining fluid rectifying plate 71a. When conductive wax is used when fixing the workpiece W and the workpiece power supply auxiliary part 73 to the machining fluid rectifying plate 71a, the melting point of the conductive wax used to fix the workpiece W to the machining fluid rectifying plate 71a is preferably higher than the melting point of the conductive wax used to fix the workpiece power supply auxiliary part 73 to the machining fluid rectifying plate 71a. For example, after fixing the workpiece W to the machining fluid rectifying plate 71a using conductive wax having a melting point of about 60°C, the workpiece power supply auxiliary part 73 is fixed to the machining fluid rectifying plate 71a using conductive wax having a melting point of about 40°C in a state where the outer peripheral surface of the workpiece power supply auxiliary part 73 is in contact with the outer peripheral surface of the workpiece W. When using the conductive paraffin under the above conditions, after the workpiece W is first fixed to the machining fluid rectifier plate 71a, the workpiece power supply auxiliary part 73 can be fixed to the machining fluid rectifier plate 71a while the outer peripheral side 73s of the workpiece power supply auxiliary part 73 is reliably in contact with the outer peripheral side Ws of the workpiece W.

[0161] Furthermore, the conductive connection portion 77 may be used between the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surfaces of the thin plate side surface holding portions 75 a and 75 b.

[0162] In addition, in the online electrical discharge machining device 1000a, the contact area between the workpiece power supply auxiliary portion 73 and the workpiece W is increased by the conductive connection portion 77, the holding force of the workpiece W is increased by the workpiece power supply auxiliary portion 73, and the flow rate of the machining fluid near the machining end portion where the machining amount, i.e., the cutting machining length, is sharply reduced, so that the thin plate can be subjected to electrical discharge cutting machining without damaging the thin plate near the machining end portion. Therefore, in the online electrical discharge machining device 1000a, the thin plate side holding portions 75a and 75b can also be omitted.

[0163] As described above, the wire electrical discharge machining device 1000 a according to the second embodiment has the same effects as those of the wire electrical discharge machining device 1000 according to the first embodiment described above.

[0164] In addition, the wire EDM apparatus 1000a includes a conductive connection portion 77 between the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply auxiliary portion 73. Thus, in the wire EDM apparatus 1000a, the contact area between the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply auxiliary portion 73 can be increased, the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply auxiliary portion 73 can be completely in contact, and the conductivity between the workpiece power supply auxiliary portion 73 and the workpiece W can be improved. Therefore, in the wire EDM apparatus 1000a, the generation of minute residual protrusions caused by the disconnection of the power supply path of the EDM power supply immediately before the cutting of the plurality of thin plates from the workpiece W is completed can be prevented, and the cutting processing quality and yield rate of the thin plates can be improved.

[0165] Implementation method 3.

[0166] Fig.15 1 is a schematic diagram showing a configuration example of the thin plate side surface holding portions 75a and 75b of the thin plate machining stabilizing portion 70b included in the wire electrical discharge machining device 1000b according to the third embodiment. Fig.15 , a machining fluid rectifying plate 71a, a workpiece pressing portion 72, a workpiece power supply auxiliary portion 73, thin plate side holding portions 75a, 75b and a thin plate portion pressing portion 76 are shown in a thin plate machining stabilizing portion 70b of the wire EDM apparatus 1000b. Fig.16 Yes Fig.15 An enlarged view showing a specific area D in FIG. Fig.17 Yes Fig.15 Another enlarged view showing a specific area D in FIG. Fig.16 , a first shape example of the thin plate side surface holding portions 75a, 75b of the thin plate processing stabilizing portion 70b is shown. Fig.17, a second shape example of the thin plate side surface holding portions 75a and 75b included in the thin plate processing stabilizing portion 70b is shown.

[0167] The wire discharge machining device 1000b according to the third embodiment is different from the wire discharge machining device 1000 according to the first embodiment in that a thin plate machining stabilizing portion 70 is replaced with a thin plate machining stabilizing portion 70b. The shapes of the thin plate side surface retaining portions 75a and 75b of the thin plate machining stabilizing portion 70b are different from those of the thin plate side surface retaining portions 75a and 75b according to the first embodiment. The other structures of the wire discharge machining device 1000b according to the third embodiment are the same as those of the wire discharge machining device 1000 according to the first embodiment, and repeated descriptions are omitted.

[0168] The thin plate side holding parts 75a and 75b provided in the processing path of the workpiece W also have the functions of preventing the swing caused by the force of the processing fluid flow from the multiple thin plates formed by the workpiece W and supplying power to each thin plate for the discharge machining power supply. Therefore, with respect to the contact state between the workpiece W and the thin plate side holding parts 75a and 75b, surface contact is more advantageous than line contact from the viewpoint of strengthening the holding force of the thin plate and stable power supply to the thin plate. That is, by setting the contact state between the workpiece W and the thin plate side holding parts 75a and 75b to surface contact, the contact area between the workpiece W and the thin plate side holding parts 75a and 75b is expanded, and the holding state of the thin plate in the cutting process achieved by the thin plate side holding parts 75a and 75b is further stabilized. The holding state of the thin plate in the cutting process achieved by the thin plate side holding parts 75a and 75b is further stabilized, thereby enabling the discharge machining speed to be increased and the cutting process to be performed, and the cutting process quality is improved.

[0169] Therefore, the contact surface 75e of the outer peripheral side surface 75d of the thin plate side holding parts 75a and 75b with the outer peripheral side surface Ws of the workpiece W is preferably shaped along the shape of the outer peripheral side surface Ws of the workpiece W. If the length of the contact surface 75e where the outer peripheral side surface 75d of the thin plate side holding parts 75a and 75b contacts the outer peripheral side surface Ws of the workpiece W in the circumferential direction of the outer peripheral side surface Ws of the workpiece W is about 3 mm, the holding force of the thin plates and the reliability of stable power supply to each thin plate are improved.

[0170] Fig.16The thin plate side holding portion 75b of the first shape example shown has a cylindrical shape whose shape in the surface direction perpendicular to the x-axis direction is circular, and the shape in the surface direction perpendicular to the x-axis direction of the contact surface 75e that contacts the peripheral side surface Ws of the workpiece W is formed into a shape along the shape of the peripheral side surface Ws of the workpiece W, that is, an arc shape. The contact state between the thin plate side holding portion 75b of the first shape example constructed as described above and the workpiece W is a surface contact in the contact surface 75e. Therefore, the thin plate side holding portion 75b of the first shape example is superior to the thin plate side holding portion 75b whose contact state with the workpiece W is a line contact from the viewpoint of the holding force of the thin plate and the stable power supply to the thin plate. In addition, here, the thin plate side holding portion 75b is described, but the same is true for the thin plate side holding portion 75a and the workpiece power supply auxiliary portion 73.

[0171] Fig.17 The thin plate side retaining portion 75b of the second shape example shown has a square column shape in which the shape in the surface direction perpendicular to the x-axis direction is a square shape, and the shape in the surface direction perpendicular to the x-axis direction of the contact surface 75e that contacts the peripheral side surface Ws of the workpiece W is formed into a shape along the shape of the peripheral side surface Ws of the workpiece W, that is, an arc shape. The contact state between the thin plate side retaining portion 75b of the second shape example constructed as described above and the workpiece W is a surface contact in the contact surface 75e. Therefore, the thin plate side retaining portion 75b of the second shape example is superior to the thin plate side retaining portion 75b whose contact state with the workpiece W is a line contact from the viewpoint of the holding force of the thin plate and the stable power supply to the thin plate. In addition, here, the thin plate side retaining portion 75b is described, but the same is true for the thin plate side retaining portion 75a.

[0172] The material used in the thin plate side retaining parts 75a and 75b preferably has discharge machining characteristics similar to those of the workpiece W. For example, when the workpiece W made of SiC is cut, the thin plate side retaining parts 75a and 75b are preferably made of silicon carbide or a sintered part of silicon carbide powder. The thin plate side retaining parts 75a and 75b are manufactured by processing a block formed by sintering SiC powder, thereby reducing the material cost of the thin plate side retaining parts 75a and 75b.

[0173] In the case of cutting a thin plate from a workpiece W made of a material such as silicon carbide or gallium nitride, a study was conducted on the case where standard metals such as copper, brass, iron, and aluminum were used for the thin plate side holding portions 75a and 75b, and the case where sintered silicon carbide was used for the thin plate side holding portions 75a and 75b. As a result, the present inventors confirmed in a machining experiment that the damage to the wire electrode 1 caused by the electric discharge machining was extremely small, based on the consumption of the wire electrode 1 by the electric discharge machining and the change in the electric discharge machining characteristics caused by the re-adhesion of machining chips generated by the electric discharge machining to the surface of the wire electrode 1.

[0174] However, silicon carbide and gallium nitride are difficult-to-process materials that have relatively high hardness among materials, are easily damaged by impact, and are difficult to process during cutting. Therefore, the thin plate side retaining parts 75a, 75b composed of silicon carbide can be easily processed with high precision based on the processing trajectory involved in the NC program. They are formed by cutting out from a block component using a non-contact thermal processing method that does not affect the hardness or brittleness of the material, namely wire discharge machining. In addition, the thin plate side retaining parts 75a, 75b composed of silicon carbide or gallium nitride are used for cutting multiple thin plates by performing discharge machining on a workpiece W composed of a semiconductor material such as silicon carbide, gallium nitride, Si (silicon) or gallium oxide (Ga2O3) through a cutting line part 1b.

[0175] As described above, in the wire electrical discharge machining device 1000b according to the third embodiment, the contact surface 75e with the outer peripheral side surface Ws of the workpiece W among the outer peripheral side surfaces 75d of the thin plate side surface holding parts 75a and 75b is formed in a shape along the shape of the outer peripheral side surface Ws of the workpiece W. That is, the contact surface 75e is formed in a concave shape with respect to the convex shape of the outer peripheral side surface Ws of the workpiece W, and is formed in a shape along the shape of the outer peripheral side surface Ws of the workpiece W. As a result, in the wire electrical discharge machining device 1000b, the contact area between the workpiece W and the thin plate side surface holding parts 75a and 75b is enlarged, the holding state of the thin plate in the cutting process by the thin plate side surface holding parts 75a and 75b is further stabilized, and the electrical discharge machining speed and the cutting process quality are improved.

[0176] Next, the hardware structure of the control unit 300 involved in Embodiments 1 to 3 is described. The functions of the control unit 300 of the wire electrical discharge machining apparatus 1000, 1000a, 1000b are realized by a processing circuit. The processing circuit is dedicated hardware installed in the control unit 300 of the wire electrical discharge machining apparatus 1000, 1000a, 1000b. The processing circuit may be a processor that executes a program stored in a memory.

[0177] Fig.18 This is a diagram showing a hardware configuration when the functions of the control unit 300 of the wire discharge machining device 1000, 1000a, 1000b are realized by dedicated hardware. The dedicated hardware, i.e., the processing circuit 51, is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof.

[0178] Fig.19 Yes means Fig.18 The figure shows a hardware structure in which the functions of the control unit 300 of the wire discharge machining devices 1000, 1000a, and 1000b are realized by a processor that executes a program stored in a memory. The processor 53 and the memory 54 are connected to each other so as to be able to communicate. The processor 53 is a CPU (Central Processing Unit), a processing device, an arithmetic device, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor). The functions of the control unit 300 are realized by the processor 53 and software, firmware, or a combination of software and firmware. The software or firmware is described as a program and stored in the memory 54. The memory 54 is a built-in memory such as a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), or an EEPROM (registered trademark) (Electrically Erasable Programmable Read-Only Memory).

[0179] Part of the functions of the control unit 300 may be implemented by dedicated hardware, and another part of the functions of the control unit 300 may be implemented by software or firmware. As described above, the functions of the control unit 300 can be implemented by hardware, software, firmware, or a combination thereof.

[0180] The configuration described in the above embodiment is merely an example, and may be combined with other known technologies, the embodiments may be combined with each other, and part of the configuration may be omitted or changed without departing from the gist.

[0181] Description of the label

[0182] 1 wire electrode, 1a parallel wire portion, 1b cutting wire portion, 2, 2a, 2b, 2c, 2d guide rollers, 2e guide groove, 3, 3a, 3b wire shaft, 4a, 4b vibration suppression guide roller, 5 processing power supply, 6a, 6b power supply unit, 7a, 7b nozzle, 7c processing liquid ejection hole, 8a, 8b wire shaft rotation control device, 9a, 9b traverse control device, 10 cutting feed table, 31 processing control device, 32 discharge waveform control device, 33 processing state acquisition unit, 34 cutting table drive control device, 35 wire travel control device, 36 workpiece pressing portion holding control device, 51 processing circuit, 53 processor, 54 memory, 70, 70a, 70b thin plate processing stabilization portion, 71, 71a, 71b processing Liquid rectifying plate, 71as, 71bs opposing surfaces, 72 workpiece pressing portion, 72a groove portion, 73 workpiece power supply auxiliary portion, 73s, 75d, Ws peripheral side surface, 74 machining liquid supply pipe, 75a, 75b thin plate side holding portion, 75c thin plate portion, 75e contact surface, 75g, 77g machining groove, 76 thin plate portion pressing portion, 77 conductive connecting portion, 78 workpiece pressing portion holding device, 100 machining mechanism portion, 200 power supply portion, 300 control portion, 1000, 1000a, 1000b wire discharge machining device, A, B, D specific areas, C center axis, PD diameter part position, PE machining end position, PH machining position, PS machining start position, W workpiece, Wg machining groove.

Claims

1. A wire electrical discharge machining device, which generates electrical discharge between a plurality of advancing cutting wires and a workpiece, performs electrical discharge machining on the workpiece by using the energy of the electrical discharge, and simultaneously cuts a plurality of wafers from the workpiece, The wire discharge machining device is characterized by having: a wire electrode which is separated from each other in parallel and has a plurality of the cutting line portions facing the workpiece; a power supply unit configured to cause discharge between the plurality of cutting line units and the workpiece; A pair of machining liquid rectifying plates, which are connected to a power source, are disposed in contact with both sides of the workpiece in a manner of sandwiching the workpiece, and are conductive; a pair of nozzles having a plurality of machining fluid ejection holes which are inserted through the plurality of cutting line portions, eject the machining fluid toward a space sandwiched by the pair of machining fluid rectifying plates, and supply the machining fluid to gaps between the plurality of cutting line portions and the workpiece; a cutting feed stage which moves the pair of machining fluid rectifying plates vertically relative to the plurality of cutting line portions; a workpiece pressing portion for holding the workpiece cut in the cutting process from above the workpiece and the plurality of cutting line portions; as well as The lower workpiece holding portion contacts the workpiece from below to hold the workpiece and has conductivity.

2. The wire discharge machining device according to claim 1, characterized in that: The pair of machining fluid rectifying plates comprises: A first machining liquid rectifying plate, which is arranged to contact one end surface of the workpiece in a direction parallel to the cutting line portion, that is, in a line parallel direction, and is connected to the power source; and A second machining liquid rectifying plate is arranged to contact the other end surface of the workpiece in the direction parallel to the lines, The lower workpiece holding portion is fixed to opposing surfaces of the first working fluid rectifying plate and the second working fluid rectifying plate in the first working fluid rectifying plate.

3. The wire discharge machining device according to claim 2, characterized in that: The lower workpiece holding portion comprises: a workpiece power supply auxiliary portion fixed to the first machining fluid rectifying plate in a state of contacting an outer peripheral side surface of a portion of the workpiece where the cutting process by the cutting line portion is completed, that is, a machining terminal end portion; and The thin plate side surface holding portion is provided over the upper and lower regions of the machining terminal portion in the upper and lower directions, and is fixed to the first machining fluid rectifying plate in a state of being in contact with the outer peripheral side surface of the workpiece.

4. The wire discharge machining device according to claim 3, characterized in that: The workpiece power supply auxiliary portion is arranged directly below the processing terminal portion.

5. The wire discharge machining device according to claim 3 or 4, characterized in that: It has a conductive connecting part, which is clamped and arranged between the workpiece power supply auxiliary part or the thin plate side holding part and the workpiece, fills the gap between the workpiece power supply auxiliary part or the thin plate side holding part and the workpiece, and has flexibility.

6. The wire discharge machining device according to claim 5, characterized in that: The conductive connection part is made of a flexible conductive material having a Young's modulus of less than or equal to 80 GPa and a resistance of less than or equal to 10 Ωcm.

7. The wire discharge machining device according to any one of claims 3 to 6, characterized in that: The contact position of the outer side surface of the thin plate side holding portion relative to the outer side surface of the workpiece is located in an interval in the cutting processing direction of the workpiece where the uncut length of the workpiece is less than or equal to 1 / 2 of the overall cutting length of the workpiece, and is located above the position where the outer side surface of the workpiece power supply auxiliary portion contacts the outer side surface of the workpiece.

8. The wire discharge machining device according to claim 7, characterized in that: The thin plate side holding portion is cut together with the workpiece, and the multiple thin plate portions of the thin plate side holding portions formed by cutting the thin plate side holding portions support and fix multiple chips that are formed by cutting from the workpiece simultaneously with the thin plate portions and separated from each other.

9. The wire discharge machining device according to any one of claims 3 to 8, characterized in that: The thin plate side retaining portion includes silicon carbide or a sintered component of silicon carbide powder.

10. The wire discharge machining device according to any one of claims 3 to 9, characterized in that: A posture changing mechanism is provided for changing the postures of the first machining fluid rectifying plate and the second machining fluid rectifying plate so as to be fixed in a state in which the first machining fluid rectifying plate and the second machining fluid rectifying plate are relatively rotated or relatively inclined with respect to the cutting line portion.

11. A wire electrical discharge machining method, wherein electrical discharge is generated between a plurality of advancing cutting wires and a workpiece, and the workpiece is subjected to electrical discharge machining by energy of the discharge, thereby simultaneously cutting a plurality of wafers from the workpiece. The wire discharge machining method is characterized by comprising: A machining fluid rectifying step of spraying machining fluid from a nozzle toward a space sandwiched by a pair of machining fluid rectifying plates connected to a power source, guiding the flow of the machining fluid toward the workpiece through the opposing surfaces of the pair of machining fluid rectifying plates, and supplying the machining fluid to gaps between the plurality of cutting line portions and the workpiece; a wafer pressing step of holding the workpiece cut in the cutting process from above the workpiece and the plurality of cutting line portions; and A wafer supporting step, in which, during the cutting process of the workpiece, a conductive lower workpiece holding portion, which is arranged over the upper and lower regions of the portion of the workpiece where the cutting process is completed, i.e., the processing terminal portion, in the cutting process direction of the workpiece and fixed to the opposing surfaces of one of the pair of processing fluid rectifying plates, contacts the workpiece from below to hold the workpiece, and power is supplied to the workpiece from the pair of processing fluid rectifying plates via the lower workpiece holding portion from the start of the cutting process of the workpiece to the end of the cutting process of the workpiece.

12. The wire discharge machining method according to claim 11, characterized in that: The pair of machining fluid rectifying plates comprises: A first machining liquid rectifying plate, which is arranged to contact one end surface of the workpiece in a direction parallel to the cutting line portion, that is, in a line parallel direction, and is connected to the power source; and A second machining liquid rectifying plate is arranged to contact the other end surface of the workpiece in the direction parallel to the lines, The lower workpiece holding portion comprises: a workpiece power supply auxiliary portion fixed to the first machining fluid rectifying plate in a state of contacting an outer peripheral side surface of a machining end portion of the workpiece where the cutting process by the cutting line portion is completed; and The thin plate side surface holding portion is provided over the upper and lower regions of the machining terminal portion in the upper and lower directions, and is fixed to the first machining fluid rectifying plate in a state of being in contact with the outer peripheral side surface of the workpiece.

13. A method for manufacturing a wafer, characterized in that: According to the wire discharge machining method described in claim 11 or 12, a plurality of wafers are cut out simultaneously from the workpiece.

14. The method for manufacturing a wafer according to claim 13, wherein: The workpiece is a semiconductor ingot. The wafer is a semiconductor wafer.

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