Wire electrical discharge processing device, wire electrical discharge processing process and wafer manufacturing process

Abstract

A wire electrical discharge machining (EDM) device comprises the following: a pair of wire parallel guide rollers arranged on both sides of a workpiece to hold the workpiece between them, each of these rollers having a plurality of wire guide grooves formed at equal intervals on an outer circumferential surface, the plurality of wire guide grooves causing a plurality of running cutting wire sections to fit into them and constraining the movement of the plurality of cutting wire sections; parallel wire extension position measuring units (52a, 52b) which measure a distance between a measuring reference surface set parallel to a virtual plane containing the plurality of cutting wire sections and a wire electrode forming the plurality of cutting wire sections;a wire guide groove detachment detection unit (53) that detects the occurrence of a change in distance based on a measurement result obtained from the parallel wire extension position measuring units (52a, 52b); and a wire condition determination unit (54) that determines, based on the detection result obtained from the wire guide groove detachment detection unit (53), whether it is a wire detachment condition in which at least one of the cutting wire sections has detached from the wire guide groove, or a wire contact condition in which all cutting wire sections are in contact with the wire guide grooves.

Description

Technical field

[0001] The present invention relates to a wire electrical discharge machining (EDM) device that performs an EDM machining operation in which a plurality of plate elements are cut together from a workpiece using a wire electrode, a wire EDM process and a wafer manufacturing process. background

[0002] In a multi-wire electrical discharge machining (EDM) system, an electrical discharge is generated between a multitude of wire electrodes and a workpiece, and a multitude of wafer elements are cut from the workpiece simultaneously. Multi-wire EDM systems are used, for example, in a semiconductor manufacturing step where multiple wafers are cut from a single ingot. Delayed detection of anomalies occurring near an electrode in the multi-wire EDM system causes various defects, such as instability of the EDM process, wire electrode breakage, variations in the thickness of the wafer elements being cut, and deterioration of the surface accuracy of the wafer elements. Therefore, various anomaly detection methods have been developed for multi-wire EDM systems.

[0003] Patent document 1 describes a wire electrical discharge machining (EDM) device comprising a high-frequency pulsed power supply unit and a control unit. To detect a short circuit, the high-frequency pulsed power supply unit applies a high-frequency pulse voltage to the parallel wire section and includes a short-circuit detection device that detects a short circuit between wires of the parallel wire section and a workpiece. The short-circuit detection device determines that a short circuit has occurred if the time between the start of the application of the high-frequency pulse voltage and the start of the rise of a current flowing between one of the wires and the workpiece is less than or equal to a predetermined reference value. Citation list

[0004] Patent Document 1: Japanese Patent Application Publication JP 2017-87395 A Summary of the invention Problem to be solved by the invention

[0005] A multi-wire electrical discharge machining (EDM) machine can be equipped with a pair of guide rollers positioned on either side of a workpiece, with the workpiece positioned between them to prevent displacement of a cutting wire, ensuring that the distance between a plurality of parallel cutting wires remains constant from the start to the end of the machining process. In this case, a plurality of wire guide grooves, defining the distance between the plurality of parallel wire electrodes, are machined into the surfaces of the guide rollers.

[0006] When multiple parallel wire electrodes are used to cut multiple plate elements from the workpiece, any of the wire electrodes can protrude from the wire guide groove. Examples of factors that cause wire electrode protrusion include a flow of machining fluid between the electrodes during machining, a repulsive force from electrical discharge, eccentricity during the rotation of a guide mechanism where wire guide grooves are formed on a cylindrical side face to arrange the wire electrodes in parallel at intervals determined by the thickness of the plate elements to be cut, and foreign matter accumulated in the wire guide grooves.

[0007] The wire electrode, lifted from the wire guide groove, can slip out of the groove due to the external force mentioned above or similar factors. As a result, the numerous wire electrodes cannot run at a predetermined parallel distance, the thickness of the plate elements cut from the ingot becomes uneven, and the productivity of the plate elements decreases.

[0008] Furthermore, the wire electrode that has emerged from the wire guide groove becomes unstable during parallel operation, leading to unstable electrical discharge machining (EDM) and likely resulting in wire electrode separation. If the wire electrode separates and is reconnected to resume EDM, the resulting groove will be formed by the wire electrode that escaped the guide groove and will deviate from its original position, created by the parallel wire electrode. This makes it difficult to resume EDM at the point of separation. Therefore, detecting anomalies in multi-wire EDM equipment is crucial.

[0009] However, the wire electrical discharge machining device described in patent document 1 detects an anomaly based on a current value between the electrodes, so that it is not possible to detect a defect that does not occur in the current value, and it is not possible to accurately detect a defect caused by a positional displacement of a wire electrode, which is problematic.

[0010] The present invention was made taking into consideration the foregoing, and its objective is to provide a wire electrical discharge machining device capable of accurately detecting a defect caused by a positional displacement of a wire electrode. Means to solve the problem

[0011] To solve the problems described above and achieve the objective, a wire electrical discharge machining (EDM) device according to the present invention generates an electrical discharge between a plurality of moving cutting wire sections and a workpiece in order to perform EDM machining of the workpiece using the energy generated by the electrical discharge, and simultaneously cuts a plurality of wafers from the workpiece. The wire EDM device comprises: a wire electrode comprising a plurality of parallel, spaced-apart cutting wire sections and a section facing the workpiece; a power supply unit for generating an electrical discharge between the plurality of cutting wire sections and the workpiece;a pair of wire parallel guide rollers arranged on both sides of the workpiece to hold the workpiece between each other, each of these rollers having a plurality of wire guide grooves formed at equal intervals on its outer circumferential surface, the plurality of wire guide grooves causing the plurality of movable cutting wire areas to fit into them and restricting the movement of the plurality of cutting wire areas;and a parallel wire extension position measuring unit for measuring the distance between a measuring reference surface set parallel to a virtual plane containing the plurality of cutting wire areas and the wire electrode forming the plurality of cutting wire areas. The wire electrical discharge machining (EDM) device comprises: a wire guide groove detachment detection unit for detecting the occurrence of a change in distance based on a measurement result obtained from the parallel wire extension position measuring unit; a wire condition determination unit for determining whether a wire detachment condition exists, in which at least one of the cutting wire areas has detached from the wire guide groove, or a wire contact condition, in which all cutting wire areas are in contact with the wire guide grooves, based on a detection result obtained from the wire guide groove detachment detection unit;and a processing control unit for controlling the stop or continuation of the electrical discharge machining process based on a determination result obtained from the wire condition determination unit. Effects of the invention

[0012] The present invention achieves the effect that it is possible to provide a wire electrical discharge machining device that is able to accurately detect a defect caused by a positional displacement of a wire electrode. Brief description of the drawings Fig. Figure 1 is a concept diagram illustrating an exemplary configuration of a wire electrical discharge machining (EDM) machine according to a first embodiment. Fig. Figure 2 is a schematic diagram illustrating an exemplary configuration of a wire elongation condition monitoring unit of the wire electrical discharge machining device according to the first embodiment. Fig. Figure 3 is a perspective view illustrating an exemplary arrangement of a parallel wire extension position measuring unit in relation to the cutting wire area in the wire electrical discharge machining device according to the first embodiment. Fig. Figure 4 is a block diagram showing exemplary configurations of a control unit and the wire extension status monitoring unit included in the wire electrical discharge machining device according to the first embodiment. Fig. Figure 5 is a diagram showing a positional relationship between a wire parallel guide roller, parallel parallel wire areas and a guide roller holder in the wire electrical discharge machining device according to the first embodiment. Fig. Figure 6 is a schematic diagram showing the parallel wire section which is extended in a plurality of wire guide grooves in the wire parallel guide roller which is included in the wire electrical discharge machining device according to the first embodiment. Fig. Figure 7 is a first schematic diagram showing an example of a state in which the parallel wire area is detached from the wire guide groove in the wire parallel guide roller included in the wire electrical discharge machining device according to the first embodiment. Fig. Figure 8 is a second schematic diagram showing an example of the state in which the parallel wire section is detached from the wire guide groove in the wire parallel guide roller included in the wire electrical discharge machining device according to the first embodiment. Fig. Figure 9 is a diagram that shows an example of a detection value of a wire guide groove detachment detection unit in the Fig. The condition shown in section 6 is displayed. Fig. 10 is a diagram that shows an example of a detection value of the wire guide groove detachment detection unit in which in Fig. The depicted state is shown in section 7. Fig. Figure 11 is a diagram that shows an example of a detection value of the wire guide groove detachment detection unit in the Fig. The condition shown in section 8 is displayed. Fig. Figure 12 is a flowchart illustrating the operation of the wire electrical discharge machining device according to the first embodiment during cutting. Fig. Figure 13 is a schematic diagram illustrating an exemplary configuration of a wire contact processing condition monitoring unit of the wire electrical discharge machining device in a second embodiment. Fig. Figure 14 is a block diagram showing exemplary configurations of the control unit and the wire contact processing status monitoring unit included in the wire electrical discharge machining device in the second embodiment. Fig. Figure 15 is a characteristic curve diagram showing a time of switching between the application of the processing voltage and the wire contact detection of the wire electrical discharge machining device in the second embodiment. Fig. Figure 16 is a schematic diagram showing an example of a state in which the parallel wire section is released from the wire guide groove in the wire parallel guide roller of the wire electrical discharge machining device in the second embodiment. Fig. 17 is a concept diagram that represents a detection value corresponding to the wire solution state in Fig. 16 and shows the determination of a state according to the recorded value. Fig. Figure 18 is a diagram illustrating a configuration in which each function of the control unit according to the first and second embodiments is implemented by hardware. Fig. Figure 19 is a diagram illustrating a configuration in which each function of the control unit according to the first and second embodiments is implemented by software. Description of the embodiments

[0013] In the following, a wire electrical discharge machining (EDM) device, a wire EDM process, and a wafer manufacturing process according to each embodiment are described in detail with reference to the drawings. First embodiment.

[0014] A multi-wire electrical discharge machining (EDM) machine is used, for example, in a semiconductor manufacturing step for cutting multiple semiconductor wafers together from a single ingot. In the multi-wire EDM machine, thin sheets to be cut together are sliced ​​by an electrical discharge generated between a workpiece and multiple parallel-spaced cutting wire sections facing the workpiece. Therefore, in the multi-wire EDM machine, the spacing between the parallel cutting wire sections significantly influences the thickness of the thin sheets to be cut.

[0015] Therefore, the multi-wire electrical discharge machining (EDM) device is equipped with a pair of wire parallel guide rollers arranged on both sides of the workpiece, with the workpiece positioned between them to prevent positional displacement of a multitude of parallel cutting wire areas, so that the distance between the cutting wire areas does not change from the beginning of machining to the end of machining.

[0016] A multitude of V-shaped wire guide grooves, defining the distance between the respective wire electrodes, are machined into the surfaces of the wire parallel guide rollers. Wire electrodes, individually positioned with respect to each of the wire guide grooves, extend between the pair of wire parallel guide rollers to form the cutting wire sections.

[0017] The wire guide grooves are formed on the surface of each wire parallel guide roller at a spacing designed for cutting thin sheets that are to be cut together with a desired sheet thickness. During electrical discharge machining (EDM), the pair of wire parallel guide rollers ensures that the cutting wire sections run parallel, while the multiple wire electrodes are restricted in such a way as to maintain the spacing between the multiple wire electrodes.

[0018] When machining thin plates with a multi-wire electrical discharge machining (EDM) machine, a machining fluid is expelled from a nozzle along a cut groove in the direction of extension of a cutting wire. When a columnar ingot is being cut, the flow rate of the machining fluid is adjusted according to the cutting thickness. However, the setting of the machining fluid flow rate affects the vibrations exerted on the wire electrodes and the voltage fluctuations of the wire electrodes. Furthermore, if the discharge energy is increased to accelerate the discharge cutting process, the repulsive force caused by the discharge also increases. This increase in the repulsive force caused by the electrical discharge also affects the vibrations exerted on the wire electrodes and the voltage fluctuations of the wire electrodes.Alternatively, foreign bodies, such as machining residues generated during cutting, can enter the wire guide groove of the wire parallel guide roller, causing the corresponding area of ​​the wire electrode to be locally flat due to the foreign bodies in the wire guide groove.

[0019] Furthermore, the wire electrodes are pushed out in a direction opposite to the direction of the machined surface of the ingot and bent by the impact force of the electrical discharge. The direction of the machined surface of the ingot is a machining progress direction of the ingot by the wire electrodes and a cutting progress direction of the ingot by the wire electrodes. The direction opposite to the direction of the machined surface of the ingot can be referred to as the anti-machining progress direction or anti-cutting progress direction. That is, the wire electrodes are pushed out in the anti-machining progress direction and bent by the impact force of the electrical discharge. The impact force of the electrical discharge that pushes the wire electrodes out in the anti-machining progress direction is called the electrical discharge repulsion force.

[0020] Due to the various disturbances described above, the wire electrode is not pressed against the deepest part of the wire guide groove, but rather against an inclined surface on one side of the wire guide groove in the form of a V-groove. Furthermore, the wire electrode is detached from the wire guide groove and slides along the outer circumferential surface of the wire parallel guide roller in an area between the wire guide groove itself and an adjacent wire guide groove, and continues to travel in this state. Consequently, as the electrical discharge cutting progresses through the cutting wire area, a region is encountered where the thickness of the subsequently processed thin sheets changes rapidly, making it impossible to perform a uniform thin sheet cutting operation.

[0021] In semiconductor wafers, the occurrence of cracks or chips, even in a single area, leads to problems such as reduced yield during the polishing step of the sliced ​​wafer or in subsequent semiconductor manufacturing processes. Therefore, cracks or chips in semiconductor wafers significantly reduce their commercial value.

[0022] This means that in electrical discharge cutting, where multiple plate elements are cut from the workpiece using wire electrodes, the flow rate of the machining fluid, which is fed into a gap between the thin plates being formed, is increased to improve the extraction of machining waste generated by the electrical discharge and the cooling of wires heated by the electrical discharge energy. This increases the pressure of the machining fluid flow received by each wire electrode, thus causing the wire electrode to vibrate. Furthermore, the wire electrode is vibrated by an electrical discharge repulsion force that is proportional to the electrical discharge energy.Furthermore, the wire electrode is vibrated by machining debris that has accumulated in the wire guide groove of the wire parallel guide roller, or by debris that clogs the wire guide groove. The wire electrode, vibrated during machining as described above, dislodges itself from a constrained position in the deepest part of the V-shaped wire guide groove, causing the wire electrode to cut the workpiece at a parallel distance that deviates from the target value.

[0023] At the point where the wire electrode's positional displacement occurs, the groove milled into the workpiece is deflected from its intended position, resulting in a positional shift of the groove itself. The area where this displacement occurs creates resistance to the flow of machining fluid into and out of the groove, reducing the likelihood of fluid replacement. Consequently, after this wire electrode displacement, the machining process becomes unstable, the machining performance deteriorates, the thickness of thin plates tends to be uneven, and wire breakage may occur.

[0024] If the workpiece consists of, for example, an ingot made of a silicon carbide (SiC) crystal and an ingot made of a gallium nitride (GaN) crystal, the distance between the installed pair of parallel wire guide rollers increases accordingly with the increasing diameter of the ingot and thus the increasing diameter of the semiconductor wafer. Therefore, it is more likely that the wire electrode will bend and become detached from the wire guide groove of the wire guide roller.

[0025] In the following, the thin sheet cut and separated by the cutting process will be referred to as a wafer.

[0026] Fig. Figure 1 is a concept diagram illustrating an exemplary configuration of a wire electrical discharge machining (EDM) machine 1000 according to a first embodiment. Fig. Figure 2 is a schematic diagram illustrating an exemplary configuration of a wire elongation condition monitoring unit 400 of the wire electrical discharge machining device 1000 according to the first embodiment. Fig. Figure 2 illustrates a positional relationship between a workpiece W, wire parallel guide rollers 51a and 51b, guide roller holders 55a and 55b, nozzles 7a and 7b, damping guide rollers 4a and 4b and a power supply unit 200. Fig. Figure 2 shows a state in which the electrical discharge machining (EDM) cutting is carried out through cutting wire sections 1b and the wire EDM cutting performed on the workpiece W in a column shape has progressed to a position that corresponds to approximately half the diameter of the workpiece W. Fig. Figure 2 shows the thin plate processing stabilization unit 70 for processing thin plates, but this is not shown. Fig. Figure 3 is a perspective view showing an exemplary arrangement of a parallel wire extension position measuring unit 52a in relation to the cutting wire area 1b in the wire electrical discharge machining device 1000 according to the first embodiment. Fig. Figure 3 shows a state in which the cutting wire sections 1b, which are located between the wire parallel guide rollers 51a and 51b of the wire extension state monitoring unit 400, which is included in the wire electrical erosion processing device 1000, run over the guide roller holder 55a.

[0027] The wire electrical discharge machining (EDM) machine 1000 is a multi-wire EDM machine that performs EDM machining using a wire electrode 1. Fig. 2 and Fig. 3 An arrow 101 indicates the direction of travel of the cutting wire sections 1b. Fig. 2 An arrow 102 indicates the direction of the processing fluid flow.

[0028] Fig. Figure 1 shows the x-axis, y-axis, and z-axis of a three-axis Cartesian coordinate system. The y-axis direction corresponds to the direction of travel of the wire electrode 1 on the workpiece W, i.e., the direction of travel of the wire electrode 1 with respect to the workpiece W, which is arranged in the wire electrical discharge machining (EDM) machine 1000. The z-axis direction corresponds to the vertical direction of the wire EDM machine 1000. The vertical direction of the wire EDM machine 1000 is an upward and downward direction, i.e., the vertical direction. The x-axis direction corresponds to the direction in which areas of the wire electrode 1 are arranged parallel to the workpiece W, i.e., the direction in which the areas of the wire electrode 1 are arranged parallel to the workpiece W in the wire EDM machine 1000.The x-axis direction can be described as a direction parallel to the longitudinal direction of the workpiece W arranged in the wire electrical discharge machining device 1000.

[0029] The wire electrical discharge machining (EDM) machine 1000 comprises a machining mechanism unit 100, which performs EDM cutting on the workpiece W using the wire electrode 1; a power supply unit 200, which provides the power supply; a control unit 300, which controls the wire EDM machine 1000; and a wire elongation status monitoring unit 400. The wire EDM machine 1000 cuts a variety of plate elements simultaneously from the workpiece W. Examples of materials for the workpiece W include tungsten, molybdenum, silicon carbide, monocrystalline silicon, monocrystalline silicon carbide, gallium nitride, and polycrystalline silicon. Silicon carbide is also known as "Tanka Keiso" in Japanese. Hereinafter, the EDM cutting process can be referred to simply as cutting.

[0030] The machining mechanism unit 100 includes a plurality of guide rollers 2, coils 3, damping guide rollers 4a and 4b, nozzles 7a and 7b, coil rotation controls 8a and 8b, cross control devices 9a and 9b, and a cutting feed stage 10. The plurality of guide rollers 2 includes a guide roller 2a, a guide roller 2b, a guide roller 2c, and a guide roller 2d. The coils 3 include a coil 3a and a coil 3b.

[0031] The multiple guide rollers 2 guide the wire electrode 1. Each of the guide rollers 2a, 2b, 2c, and 2d is mounted so that it can rotate about its corresponding axis of rotation. The guide rollers 2a, 2b, 2c, and 2d are spaced apart from one another and arranged so that their axes of rotation are parallel to each other. Because the axes of rotation of the guide rollers 2a, 2b, 2c, and 2d are parallel to each other, the wire electrode 1 can run with high accuracy. The axes of rotation of the guide rollers 2a, 2b, 2c, and 2d are arranged parallel to the x-axis.

[0032] A wire electrode 1 is wound around the guide rollers 2a, 2b, 2c, and 2d in a number of turns at intervals along the axis of rotation of each of the guide rollers 2a, 2b, 2c, and 2d. These sections of the wire electrode 1 are collectively referred to as parallel wire sections 1a. The sections of the parallel wire sections 1a facing the workpiece W are each referred to as cutting wire sections 1b. The cutting wire sections 1b comprise a plurality of parallel parallel wire sections 1a. The cutting wire sections 1b are preferably arranged parallel to each other.

[0033] A plurality of wire guide grooves 2e are formed at equal intervals on the surfaces of the guide rollers 2a, 2b, 2c, and 2d. By winding the wire electrode 1 around the surfaces of the guide rollers 2a, 2b, 2c, and 2d along the plurality of wire guide grooves 2e, the guide rollers 2a, 2b, 2c, and 2d maintain a constant distance between the areas of the wire electrode 1, i.e., the distance between the areas of the wire electrode 1 of the parallel wire section 1a. In the wire electrical discharge machining (EDM) device 1000, the cutting wire sections 1b are arranged parallel to each other and at equal intervals, so that the thicknesses of the plurality of plate elements cut from the workpiece W can be made uniform, and the cross-sections of the plurality of plate elements can be made parallel to each other. The number of guide rollers 2 need not necessarily be four, but can also be three or fewer, or five or more.

[0034] Coils 3a and 3b cause the wire electrode 1 to undergo a winding cycle. Coil 3a performs the winding cycle. Coil 3b performs the winding cycle. Coil rotation control 8a and lateral control device 9a control coil 3a. Coil rotation control 8b and lateral control device 9b control coil 3b.

[0035] The coil rotation control 8a controls the rotation of coil 3a and controls the movement of wire electrode 1. For example, the coil rotation control 8a controls the direction and speed of wire electrode 1. The coil rotation control 8b controls the rotation of coil 3b and controls the movement of wire electrode 1. For example, the coil rotation control 8b controls the direction and speed of wire electrode 1.

[0036] The transverse control device 9a controls the position of coil 3a in the x-direction according to an unwinding position of the wire electrode 1. The transverse control device 9b controls the position of coil 3b in the x-direction according to a winding position of the wire electrode 1. The position control of coils 3a and 3b by the transverse control devices 9a and 9b is referred to as transverse control. Through transverse control, coils 3a and 3b ensure that the wire electrode 1 runs stably and with high accuracy.

[0037] The wire electrode 1, unwound from coil 3a, is wound around guide roller 2b, guide roller 2a, guide roller 2d, and guide roller 2c in this sequence, and then the winding continues from guide roller 2b. The wire electrode 1 is wound onto coil 3b after passing through guide rollers 2a, 2b, 2c, and 2d several times in the manner described above.

[0038] The workpiece W is placed on a workpiece mounting plate 42, which is attached to the cutting feed stage 10 described later. The workpiece mounting plate 42, to which the workpiece W is attached, is arranged between the wire parallel guide roller 51a and the wire parallel guide roller 51b in the Y-axis direction.

[0039] The wire parallel guide rollers 51a and 51b are arranged on both sides of the workpiece W, so that they hold the workpiece W between them in the Y-axis direction. The wire parallel guide rollers 51a and 51b are installed between the damping guide roller 4a and the damping guide roller 4b in the Y-axis direction. The wire parallel guide rollers 51a and 51b restrict the movement of the wire electrode 1 in the x-direction. In particular, the wire parallel guide rollers 51a and 51b restrict the movement of the parallel wire sections 1a and the cutting wire sections 1b in the x-direction.

[0040] Each of the wire parallel guide rollers 51a and 51b has an axis of rotation similar to the guide rollers 2a, 2b, 2c, and 2d and is mounted so that it can rotate about the corresponding axis of rotation. The wire parallel guide rollers 51a and 51b are spaced apart from each other in the Y-axis direction and arranged so that their axes of rotation are parallel to each other. Because the axes of rotation of the wire parallel guide rollers 51a and 51b are parallel to each other, the wire electrode 1 can run with high accuracy. The axes of rotation of the wire parallel guide rollers 51a and 51b are arranged parallel to the x-axis.

[0041] On the surfaces of the wire guide rollers 51a and 51b, a plurality of wire guide grooves 51c are formed at predetermined equal intervals. As the wire electrode 1 runs along the surfaces of the wire guide rollers 51a and 51b along the plurality of wire guide grooves 51c, the wire guide rollers 51a and 51b maintain a constant distance between the areas of the wire electrode 1, i.e., the distance between the areas of the wire electrode 1 and the parallel wire areas 1a. In the wire electrical discharge machining (EDM) device 1000, the cutting wire areas 1b are arranged parallel to each other and at equal intervals, so that the thicknesses of the plurality of plate elements cut from the workpiece W can be made uniform and the cross-sections of the plurality of plate elements can be made parallel to each other.

[0042] This means that the wire parallel guide rollers 51a and 51b guide the movement of the parallel wire sections 1a and the cutting wire sections 1b of the wire electrode 1, which run at equal intervals along the axis of rotation of each of the guide rollers 2a, 2b, 2c, and 2d and are separated from each other, and reduce the vibration of the parallel wire sections 1a in a section of the workpiece thickness W. Consequently, the parallel wire parallel guide rollers 51a and 51b ensure that the parallel wire sections 1a and the cutting wire sections 1b run with high accuracy while maintaining an alignment distance between them.

[0043] As in Fig. As shown in Figure 2, the wire parallel guide rollers 51a and 51b are supported by a pair of guide roller holders 55a and 55b, which are provided with bearings that support the wire parallel guide rollers 51a and 51b in such a way that the wire parallel guide rollers 51a and 51b can be rotated about the corresponding axes of rotation.

[0044] The pair of guide roller holders 55a and 55b is attached to both sides of the workpiece W, such that the axes of rotation of the wire parallel guide rollers 51a and 51b are arranged parallel to the x-axis direction in order to hold the workpiece W between them in the y-axis direction. As shown in Fig. As shown in Figure 3, the guide roller holder 55a supports a rotating shaft 51a2 of the parallel wire guide roller 51a to support the parallel wire guide roller 51a in a state where an upper end region 51a1 of the parallel wire guide roller 51a projects upward from a surface 55a1 of the guide roller holder 55a. Similarly, the guide roller holder 55b supports a rotating shaft of the wire guide roller 51b to support the wire guide roller 51b in a state where an upper end region (not shown) of the wire guide roller 51b projects upward from a surface (not shown) of the guide roller holder 55b.

[0045] Nozzle 7a is arranged between damping guide roller 4a and the workpiece W in the y-axis direction. Nozzle 7b is also arranged between damping guide roller 4b and the workpiece W in the y-axis direction. Nozzles 7a and 7b are positioned above the plurality of parallel wire sections 1a in a state where the plurality of parallel wire sections 1a are enclosed between the wire guide rollers 51a and 51b and the nozzles 7a and 7b, respectively, and in a state where nozzles 7a and 7b are spaced apart from the plurality of parallel wire sections 1a in the Z-axis direction. The interior of nozzles 7a and 7b is filled with the machining fluid, which is supplied from a machining fluid supply line 62.Nozzles 7a and 7b each include a machining fluid discharge opening 7c, through which the machining fluid filled in nozzles 7a and 7b is discharged towards the workpiece W in the thin-plate machining stabilization unit 70. The parallel wire sections 1a run below the machining fluid discharge openings 7c of nozzles 7a and 7b.

[0046] A machining fluid tank and a pump can be connected to nozzles 7a and 7b. The thin-plate machining stabilization unit 70, to which the workpiece W is attached, can be installed in a machining tank in which the machining fluid is stored, and electrical discharge machining can be carried out while the workpiece W is immersed in the machining fluid.

[0047] In the wire electrical discharge machining (EDM) device 1000, the parallel wire guide rollers 51a and 51b restrict the movement of the wire electrode 1 in the x-direction, and furthermore, the damping guide rollers 4a and 4b restrict the movement of the wire electrode 1 in the z-direction, thereby reducing the vibration of the wire electrode 1 in the cutting wire area 1b. Although the areas of the parallel wire sections 1a facing the workpiece W are referred to as cutting wire areas 1b, as described above, areas of the parallel wire sections 1a above the wire guide roller 51a and above the wire guide roller 51b, as well as areas between the wire guide roller 51a and the wire guide roller 51b, are also referred to as cutting wire areas 1b. In the wire electrical discharge machining device 1000, the damping guide roller 4a and the damping guide roller 4b can be omitted.

[0048] The cutting feed stage 10 changes the relative positions of the workpiece W and the cutting wire sections 1b. In particular, the cutting feed stage 10 changes the relative positions of the workpiece mounting plate 42, to which the workpiece W is attached, and the cutting wire sections 1b. In the first embodiment, the positions of the cutting wire sections 1b are fixed in the Z-axis direction, and the cutting feed stage 10 is movable in the Z-axis direction. The cutting feed stage 10 moves the workpiece W in the upward and downward directions. By moving the cutting feed stage 10 in the upward and downward directions, the wire EDM machining device 1000 causes the workpiece W to approach or move away from the cutting wire sections 1b, thereby cutting the workpiece W. Additionally, the EDM process forms a machined groove along each of the cutting wire sections 1b in the workpiece W.It should be noted that the cutting feed stage 10 can be moved in the x-axis direction, y-axis direction and z-axis direction.

[0049] The processing mechanism unit 100 can include components such as a guide roller that reduces the vibration of the wire electrode 1, a load cell that measures the tension of the wire electrode 1, and a dancer roller that controls the tension of the wire electrode 1. The processing mechanism unit 100 can maintain the tension of the wire electrode 1 within a suitable range for its operation using the load cell and the dancer roller. For example, the dancer roller can control the tension of the wire electrode 1 by changing the unwinding and winding speeds of the wire electrode 1.

[0050] The power supply unit 200 includes a processing power supply 5 and power supply contact units 6a and 6b. The processing power supply 5 supplies the wire electrode 1 with current via the power supply contact units 6a and 6b, which are connected to the wire electrode 1. The processing power supply 5 also supplies the workpiece W with current via the processing fluid flow compensation plate 71a, which is described later. The power supply contact units 6a and 6b, which are the power supply means, consist of an arrangement of a plurality of power supply contacts 11. The power supply contacts 11 are insulated from each other. Each area of ​​the wire electrode 1 of the cutting wire area 1b is supplied with current via the power supply contact 11, and a processing current flows through it.In the processing power supply 5, which is a power supply device, a power supply-side connection is electrically connected to each of the power supply contact units 6a and 6b, and a grounding-side connection is electrically connected to the workpiece W. Therefore, a voltage pulse output by the processing power supply 5 is applied between the wire electrode sections 1 and the cutting wire sections 1b and the workpiece W. The processing power supply 5, the multiple power supply contacts 11, and the workpiece W5 are electrically connected to each other via power supply lines 12.

[0051] The thin-sheet machining stabilization unit 70 is a mechanism that prevents a power failure to the individual thin sheets during cutting. The thin-sheet machining stabilization unit 70 is arranged between the damping guide roller 4a and the damping guide roller 4b, and between the nozzle 7a and the nozzle 7b. The thin-sheet machining stabilization unit 70 includes the machining fluid flow compensating plate 71a and a machining fluid flow compensating plate 71b, which form a pair of machining fluid flow compensating plates 71, as well as a workpiece holding unit 72.

[0052] The machining fluid flow compensating plates 71a and 71b, which form the pair of machining fluid flow compensating plates 71, are conductive, arranged parallel to the direction of travel of the cutting wire sections 1b, and align the flow of the machining fluid. The machining fluid flow compensating plates 71a and 71b are arranged between the nozzle 7a and the nozzle 7b. The machining fluid flow compensating plates 71a and 71b have a plate shape or a rectangular parallelepiped shape and are arranged such that their facing surfaces are parallel to each other.

[0053] The machining fluid flow compensation plate 71a is the first machining fluid flow compensation plate of the pair of machining fluid flow compensation plates 71 and is connected to the machining power supply 5. Consequently, the electrical discharge machining power is delivered from the machining fluid flow compensation plate 71a, which is in contact with an end face of the workpiece W, to the workpiece W.

[0054] The machining fluid flow compensation plate 71b is a second machining fluid flow compensation plate of the pair of machining fluid flow compensation plates 71 and is arranged parallel to the machining fluid flow compensation plate 71a in a state in which the workpiece W attached to the workpiece mounting plate 42 is enclosed between the machining fluid flow compensation plate 71a and the machining fluid flow compensation plate 71b.

[0055] The machining fluid flow compensation plate 71b is in close contact with the workpiece W and, together with the machining fluid flow compensation plate 71a, forms a path to guide the machining fluid supplied by the nozzles 7a and 7b to the workpiece W. The machining fluid is fed from the nozzles 7a and 7b into a gap between the machining fluid flow compensation plate 71a and the machining fluid flow compensation plate 71b in the direction of the workpiece W. Consequently, the diffusion of the machining fluid in the thickness direction of the thin plates to be formed, i.e., in the x-axis direction, is reduced.

[0056] Since the current of the processing fluid supplied by the nozzles 7a and 7b is rectified in the wire electrical discharge machining device 1000 as described above, the diffusion of the processing fluid is reduced, thereby decreasing the probability that the thin plates to be formed will be shaken by the processing fluid and develop cracks.

[0057] The workpiece W is positioned between the machining fluid flow compensation plate 71a and the machining fluid flow compensation plate 71b and placed on the workpiece mounting plate 42, where it is secured within the thin-plate machining stabilization unit 70. The workpiece W is secured to the workpiece mounting plate 42 by a device (not shown) for securing the workpiece W, which is arranged on the cutting feed stage 10.

[0058] In a case where the workpiece W is a material for a semiconductor wafer, its shape is often pre-formed into a columnar shape, so that the thin sheets become circular thin plates after cutting. Here, with respect to the columnar workpiece W, a side face of the column, which forms a curved surface, is referred to as the outer circumferential surface. The workpiece W is positioned on the workpiece mounting plate 42 within the thin-plate processing stabilization unit 70 such that the outer circumferential surface faces the cutting wire sections 1b. By cutting the workpiece W using the cutting wire sections 1b, wafers, which are thin plates, are processed from the workpiece W.

[0059] When a voltage of a specific value is applied between the electrodes, i.e., in the gap between the cutting wire sections 1b and the workpiece W, and the electrode gap reaches a certain value, an electrical discharge is generated between the electrodes. This generates heat in the cutting wire sections 1b, leading to the melting of the workpiece W. As a result, numerous plate elements are cut out simultaneously. If machining fluid is introduced into the gap between the workpiece W and the cutting wire sections 1b during the cutting process, the machining residues generated between the workpiece W and the cutting wire sections 1b can be carried out of the gap.Even if the machining residues can cause a short circuit between the workpiece W and the cutting wire areas 1b, the frequency of short circuits can be reduced by supplying the machining fluid.

[0060] The workpiece holding unit 72 holds the multitude of thin plates formed from an outer circumferential surface on a cutting start area of ​​the multitude of thin plates and fixes the multitude of thin plates being formed together. By fixing the multitude of thin plates to be formed together, the workpiece holding unit 72 can reduce the wobbling of the multitude of thin plates due to vibrations of the workpiece W generated by the fluid pressure of the machining fluid flow acting on the cutting surfaces of the multitude of thin plates.

[0061] The wire elongation status monitoring unit 400 monitors the elongation status of the parallel wire areas 1a during cutting. Fig. Figure 4 is a block diagram showing exemplary configurations of the control unit 300 and the wire extension condition monitoring unit 400, which are included in the wire electrical discharge machining (EDM) machine 1000 according to the first embodiment. The wire extension condition monitoring unit 400 includes parallel wire extension position measuring units 52a and 52b, a wire guide groove release detection unit 53, and a wire condition determination unit 54. The parallel wire extension position measuring units 52a and 52b are connected to the wire guide groove release detection unit 53. The wire guide groove release detection unit 53 is connected to the wire condition determination unit 54. The wire condition determination unit 54 is connected to a machining control 31 of the control unit 300. The wire extension status monitoring unit 400 for cutting wire area 1b is thus configured.

[0062] As in Fig. 2 and Fig. As shown in Figure 3, the two parallel wire extension position measuring units 52a and 52b are installed in the guide roller holders 55a and 55b. The pair of parallel wire extension position measuring units 52a and 52b, which face the extended and parallel sections of the wire electrode 1 in the wire guide grooves 51c of the wire parallel guide rollers 51a and 51b, is installed in the guide roller holders 55a and 55b.

[0063] In the guide roller holder 55a, the parallel wire extension position measuring unit 52a is arranged in a position corresponding to a position between the pair of parallel wire guide rollers 51a and 51b, and above which the cutting wire sections 1b run. That is, in the guide roller holder 55a, the parallel wire extension position measuring unit 52a is arranged in a position that is closer to the workpiece W in the Y-axis direction than the parallel wire guide roller 51a and below the cutting wire section 1b.

[0064] In the guide roller holder 55b, the parallel wire extension position measuring unit 52b is arranged in a position corresponding to a position between the pair of parallel wire guide rollers 51a and 51b, and over which the cutting wire section 1b runs. That is, in the guide roller holder 55b, the parallel wire extension position measuring unit 52b is arranged in a position that is closer to the workpiece W in the y-axis direction than the parallel wire guide roller 51b and below the cutting wire section 1b.

[0065] The cutting wire sections 1b run above the guide roller holders 55a and 55b. In the vertical direction, the distance between the surface of each of the guide roller holders 55a and 55b and the cutting wire sections 1b is specified to be 1 mm or less. Therefore, the arrangement is designed such that the end faces of the sensors of the parallel wire extension position measuring units 52a and 52b, which are installed in the guide roller holders 55a and 55b, are at substantially the same height as the surfaces of the guide roller holders 55a and 55b. The end faces of the sensors of the parallel wire extension position measuring units 52a and 52b are the surfaces of the parallel wire extension position measuring units 52a and 52b. In the Fig. In the example shown in Figure 3, the arrangement is such that a surface 52a1, which is the end surface of the sensor of the parallel wire extension position measuring unit 52a, has essentially the same height as the surface 55a1 of the guide roller holder 55a.

[0066] It should be noted that with regard to the installation positions of the parallel wire extension position measuring units 52a and 52b in the vertical direction, the distance to the surface of each of the guide roller holders 55a and 55b does not always have to be set to 1 mm or less, as long as the distance does not cause a conflict with the cutting wire area 1b and is within a detection range of the sensors of the parallel wire extension position measuring units 52a and 52b.

[0067] The pair of parallel wire extension position measuring units 52a and 52b measures a distance L to the parallel wire sections 1a, which face the parallel wire extension position measuring units 52a and 52b in the vertical direction, during cutting in a predetermined cycle, and monitors a change in the distance L. The distance L to the parallel wire sections 1a, which face the parallel wire extension position measuring units 52a and 52b in the vertical direction, can be redefined as the distance L between the surfaces 55a1 of the guide roller holders 55a and 55b, which are predetermined measurement reference surfaces, and the parallel wire sections 1a in the vertical direction.That is, each of the two parallel wire extension position measuring units 52a and 52b measures the distance L between the surfaces 55a1 of the guide roller holders 55a and 55b, which are predetermined measuring reference surfaces, and the parallel wire areas 1a in the vertical direction during cutting.

[0068] With respect to the pair of parallel wire extension position measuring units 52a and 52b, the surfaces 55a1 of the guide roller holders 55a and 55b, which are substantially parallel to an identical virtual plane encompassing the areas of the wire electrode 1 and the cutting wire areas 1b arranged parallel between the pair of parallel wire guide rollers 51a and 51b, are defined as predetermined measurement reference surfaces. The height position of the surface 52a1 of the parallel wire extension position measuring unit 52a, which is the distal end region of each sensing unit of the parallel wire extension position measuring units 52a and 52b, is defined in accordance with the height of the measurement reference surfaces. The distal region of each sensing unit of the parallel wire extension position measuring units 52a and 52b is the end surface of each sensor of the parallel wire extension position measuring unit 52a.

[0069] Therefore, the pair of parallel wire extension position measuring units 52a and 52b measures the distance L between the distal end regions of the detection units of the pair of parallel wire extension position measuring units 52a and 52b and the parallel wire regions 1a in the vertical direction in a predetermined cycle. The pair of parallel wire extension position measuring units 52a and 52b measures the distance L between the measurement reference surfaces arranged parallel to a virtual plane that includes the plurality of cutting wire regions 1b and the regions of the wire electrode 1 that form the plurality of cutting wire regions 1b. The pair of parallel wire extension position measuring units 52a and 52b each transmits information about the distance L, which is a measurement result, to the wire guide groove detachment detection unit 53.

[0070] The pair of parallel wire extension position measuring units 52a and 52b includes as a sensor at least one eddy current displacement sensor, one capacitive displacement sensor, one line-sensitive sensor or one touch-sensitive displacement sensor and measures the distance L with the sensor.

[0071] The wire guide groove detachment detection unit 53 detects the occurrence of a change exceeding a predetermined reference value in the distance L measured by each of the parallel wire extension position measuring units 52a and 52b, based on the measurement result obtained by each of the parallel wire extension position measuring units 52a and 52b. That is, the wire guide groove detachment detection unit 53 acquires the measurement result of the distance L between the parallel wire extension position measuring units 52a and 52b and the parallel wire sections 1a in the vertical direction. The wire guide groove detachment detection unit 53 then compares the acquired measurement result of the distance L with a distance threshold, which is a predetermined reference value, and thereby detects the occurrence of a change in the distance L at which the distance L exceeds the distance threshold.This means that the wire guide groove detachment detection unit 53 detects the occurrence of a change in which the distance L exceeds a predetermined reference value.

[0072] Fig. Figure 5 is a diagram illustrating the positional relationship between the wire parallel guide roller 51a, the parallel wire sections 1a and the guide roller holder 55a in the wire electrical discharge machining device 1000 according to the first embodiment. Fig. Figure 5 illustrates a positional relationship between the guide roller holder 55a and longitudinal sections of the wire parallel guide roller 51a and the parallel wire sections 1a along the line VV in Fig. 3. That means, Fig. Figure 5 shows a positional relationship between the guide roller holder 55a and a longitudinal section passing through the rotating shaft 51a2 of the wire parallel guide roller 51a, when the parallel wire sections 1a extending between the wire parallel guide rollers 51a and 51b and the wire parallel guide roller 51a are viewed from a direction of arrow 103 in Fig. 3 are considered. Fig. Figure 5 shows a state in which the parallel wire sections 1a are hooked onto the plurality of wire guide grooves 51c in the wire parallel guide roller 51a and the parallel wire sections 1a are fitted into the plurality of wire guide grooves 51c in the wire parallel guide roller 51a. Fig. Figure 5 also shows a plane 43, which is an equal virtual plane that includes the areas of the wire electrode 1 of the parallel wire areas 1a, which are arranged parallel between the pair of wire parallel guide rollers 51a and 51b, as described above.

[0073] Fig. Figure 6 is a schematic diagram showing the parallel wire section 1a extending into a plurality of wire guide grooves 51c in the wire parallel guide rollers 51a and 51b included in the wire electrical discharge machining device 1000 according to the first embodiment. Fig. 6 is a diagram that represents a range of Fig. 5 corresponds to. Fig. Figure 6 shows a normal state in which the parallel wire sections 1a are located in the deepest areas of the wire guide grooves 51c.

[0074] Fig. Figure 7 is a first schematic diagram showing an example of a state in which the parallel wire section 1a is released from the wire guide groove 51c in the wire parallel guide rollers 51a and 51b which are included in the wire electrical discharge machining device 1000 according to the first embodiment. Fig. Figure 7 shows an anomalous state in which a region of the parallel wire areas 1a is detached from the wire guide groove 51c in the wire parallel guide roller 51a due to the disturbance described above and rests on an outer circumferential surface 51d of the wire parallel guide roller 51a.

[0075] Fig. Figure 8 is a second schematic diagram showing an example of the state in which the parallel wire section 1a detaches from the wire guide groove 51c in the wire parallel guide roller 51a, which is included in the wire electrical discharge machining device 1000 according to the first embodiment. Fig. Figure 8 shows a state in which the parallel wire section 1a, which is located in the Fig. The wire guide groove 51c, as shown in Figure 7, is detached, moved further, and the parallel wire section 1a is fitted into the adjacent wire guide groove 51c.

[0076] Fig. Figure 9 is a diagram showing an example of a detection value of the wire guide groove detachment detection unit 53 in the diagram. Fig. The condition shown in section 6 is displayed. Fig. Figure 10 is a diagram showing an example of a detection value of the wire guide groove detachment detection unit 53 in the Fig. The depicted state is shown in section 7. Fig. Figure 11 is a diagram showing an example of a detection value of the wire guide groove detachment detection unit 53 in the Fig. The condition shown in section 8 illustrates this. Fig. Figures 9 to 11 correspond to the extension states of the parallel wire sections 1a and illustrate graphically the detection values ​​of the distance L between the parallel wire sections 1a, which are opposite the parallel wire extension position measuring units 52a and 52b, and the parallel wire extension position measuring units 52a and 52b in the vertical direction, which are converted into electrical signals. The horizontal axis in each of the Fig. 9 to 11 represents the measurement time. The vertical axis in each of the Fig. 9 to 11 represents the detection value of the distance L converted into an electrical signal.

[0077] The distance L between the detection units of the parallel wire extension position measuring units 52a and 52b and the parallel wire sections 1a opposite the detection units, where the distance L is measured from the parallel wire extension position measuring units 52a and 52b, is determined by the position of the wire guide grooves 51c in the vertical direction and does not vary significantly under stable electrical discharge machining conditions. However, as shown in the Fig. 7 and Fig. As shown in Figure 8, an anomaly in the alignment state of the parallel wire section 1a may occur due to a disturbance, such as a change in the processing fluid current in conjunction with a change in the processing conditions or a fluctuation in the wire voltage due to an increase in the discharge energy.

[0078] This means that during cutting in the wire EDM machine 1000, the machining fluid is expelled from nozzles 7a and 7b in the direction of the machining grooves along the extension direction of the parallel wire section 1a. When a workpiece W is cut in a columnar shape, the flow rate of the machining fluid is adjusted according to the cutting thickness. However, the setting of the machining fluid flow rate is a factor influencing the vibrations exerted on the parallel wire sections 1a and influencing the voltage fluctuations of these sections. Furthermore, if the discharge energy is increased to accelerate the EDM machining, the repulsive force caused by the discharge also increases.The increase in the repulsive force due to the electrical discharge is also a factor in the vibrations exerted on the parallel wire sections 1a and a factor in the voltage fluctuations of the parallel wire sections 1a. Alternatively, foreign bodies, such as machining residues generated during cutting, can enter one of the wire guide grooves 51c of the wire parallel guide rollers 51a and 51b, which causes the corresponding area of ​​the parallel wire section 1a to be locally flattened due to the foreign bodies in the wire guide groove 51c.

[0079] During cutting in the wire electrical discharge machining (EDM) machine 1000, the parallel wire sections 1a are pushed out in a direction opposite to the direction of the workpiece surface W being machined and bent by the impact force of the EDM process. The direction of the workpiece surface W is the machining progress direction of the workpiece W through the parallel wire sections 1a. The direction opposite to the machining progress direction of the workpiece surface W can be referred to as the anti-machining progress direction. That is, the parallel wire sections 1a are pushed out in the anti-machining progress direction and bent by the impact force of the electrical discharge during cutting.The impact force of the electrical discharge, which pushes the parallel wire area 1a out in the anti-processing progress direction during cutting, is called the electrical discharge repulsion force.

[0080] During cutting in the wire electrical discharge machining device 1000, the parallel wire section 1a is not pressed against the deepest areas of the wire guide grooves 51c of the wire parallel guide rollers 51a and 51b due to the disturbance described above, but against inclined surfaces on one side of the wire guide grooves 51c in the form of a V-groove, and furthermore the parallel wire section 1a is released from the wire guide grooves 51c and runs on the outer circumferential surfaces 51d of the wire parallel guide rollers 51a and 51b in areas between the wire guide grooves 51c and the adjacent wire guide grooves 51c, and in this state the parallel wire section 1a continues to run.As a result, as the electrical discharge processing progresses through the parallel wire area 1a, an area occurs where the plate thickness in the subsequently processed thin plates changes rapidly, and thus it is not possible to perform a collective cutting of thin plates with uniform plate thickness.

[0081] Out of Fig. Figure 9 shows that the distance L remains constant at a distance L1 and that the parallel wire section 1a is in a normal state, in which it is fitted into the deepest part of the wire guide groove 51c. Fig. It is evident from Figure 10 that the distance L begins to change to a distance L2 from time T1, that the parallel wire section 1a begins to detach from the wire guide grooves 51c of the wire parallel guide rollers 51a and 51b, and that it has slipped onto the outer circumferential surfaces 51d of the wire parallel guide roller 51a. Furthermore, it is evident from Fig. 11 can be seen that the distance L2 begins to change to a distance L3 from time T2, that the parallel wire section 1a released from the wire guide groove 51c has moved further and that the parallel wire section 1a has been fitted into the adjacent wire guide groove 51c.

[0082] That means, in the Fig. In the wire elongation state of the parallel wire sections 1a shown in Figure 6, the sections of the wire electrode 1 are all elongated while fitted into the wire guide grooves 51c. Therefore, the distance L obtained from each of the parallel wire elongation position measuring units 52a and 52b is measured as the distance L1 with a constant value, as shown in Figure 6. Fig. 9 shown, recorded.

[0083] In Fig. 7 is a region of the wire electrode 1 of the parallel wire section 1a detached from a region of the wire guide grooves 51c under the plurality of wire guide grooves 51c, whereby the detection value of each of the parallel wire extension position measuring units 52a and 52b, i.e. the distance L, changes from the distance L1 in a stable state to the distance L2, as in Fig. 10 is shown, and the wire guide groove detachment detection unit 53 detects that an anomaly has occurred in the wire elongation state of the parallel wire areas 1a.

[0084] In Fig. 8. The area of ​​the wire electrode 1 of the parallel wire section 1a, which has detached from the wire guide rail 51c, is inserted into the adjacent wire guide groove 51c, and thereby the distance L from distance L2 to distance L3 changes with respect to the detection value of each of the parallel parallel wire extension position measuring units 52a and 52b, as shown in Fig. 11 shown, and the wire guide groove detachment detection unit 53 detects that the wire elongation state of the parallel wire areas 1a has changed.

[0085] As described above, the parallel wire extension position measuring units 52a and 52b detect a change in the distance L during cutting, which indicates the extension position of the parallel wire sections 1a in the height direction to be monitored. The parallel wire extension position measuring units 52a and 52b then send information about the detected distance L values, which are measurement results, to the wire guide groove release detection unit 53. The wire guide groove release detection unit 53 converts the detected values ​​from the parallel wire extension position measuring units 52a and 52b into electrical signals and calculates a change in distance L as a difference ΔL. In the example in Fig. 7. The change from distance L1 to distance L2 is calculated as the difference ΔL.

[0086] In a case where the difference ΔL exceeds a predetermined reference value, the wire guide groove detachment detection unit 53 transmits information about the difference ΔL to the wire condition determination unit 54, thereby notifying the wire condition determination unit 54 of the occurrence of a change in the distance L that exceeds the predetermined reference value. The predetermined reference value is stored in the wire guide groove detachment detection unit 53.

[0087] The wire condition determination unit 54 determines, based on the detection result received from the wire guide groove detachment detection unit 53, whether the wire is in a detachment state, where at least one parallel wire section 1a has detached from the wire guide groove 51c, or in a wire contact state, where all parallel wire sections 1a are in contact with the wire guide grooves 51c. The wire condition determination unit 54 determines whether there has been a change in the elongation state of the parallel wire sections 1a by comparing the difference ΔL transmitted by the wire guide groove detachment detection unit 53 with a predetermined reference value for the distance L. If the difference ΔL exceeds the predetermined reference value for the distance L, the wire condition determination unit 54 determines that there has been a change in the elongation state of the parallel wire sections 1a, i.e.,of the elongation state of the cutting wire sections 1b. This case corresponds to a time when an anomalous parallelism of the sections of the wire electrode 1 occurs. In a case where the difference ΔL does not exceed the predetermined determination reference value of the distance L, the wire state determination unit 54 determines that there is no change in the elongation state of the parallel wire sections 1a, i.e., in the elongation state of the cutting wire sections 1b.

[0088] The wire condition determination unit 54 transmits the parallel wire extension condition information ps, which is a determination result and condition monitoring information, to the processing control 31 of the control unit 300.

[0089] The control unit 300 controls the entire wire electrical discharge machining (EDM) machine 1000. The control unit 300 controls the entire wire EDM machine 1000 based on condition monitoring information transmitted from the wire condition determination unit 54 to the wire elongation condition monitoring unit 400. The control unit 300 includes the machining control 31, a waveform control for the electrical discharge 32, a drive control for the cutting stage 34, and a wire feed control 35.

[0090] The processing control 31 controls the control for the waveform of the electrical discharge 32, the control for the drive of the cutting stage 34 and the wire feed control 35 on the basis of the parallel wire elongation state information ps, which is acquired by the wire state determination unit 54 of the wire elongation state monitoring unit 400.

[0091] The electrical discharge waveform control 32 controls the processing power supply 5 on the basis of an electrical discharge waveform command wc entered by the processing control 31 and controls the waveform of the voltage applied between the electrodes or the waveform of the current flowing between the electrodes.

[0092] The wire feed control 35 drives the coil rotation controls 8a and 8b based on a wire electrode feed command rc entered by the machining control 31 and controls the feed of the wire electrode 1. In addition, the wire feed control 35 drives the cross control devices 9a and 9b based on the wire electrode control command entered by the machining control 31 and controls the cross control.

[0093] The control for the drive of the cutting stage 34 drives the cutting feed stage 10 on the basis of a stage command sc entered by the machining control 31 and controls the relative positions of the workpiece W and the cutting wire area 1b.

[0094] Fig. Figure 12 is a flowchart illustrating the operation of the wire electrical discharge machining device 1000 according to the first embodiment during cutting.

[0095] When the cutting process is started, a step to measure the parallel wire extension position is performed in step S110. That is, the parallel wire extension position measuring units 52a and 52b measure the distance L between the measuring reference surface, which is parallel to the virtual plane and contains the multiple cutting wire areas 1b, and the areas of the wire electrode 1 that form the multiple cutting wire areas 1b, as described above. The parallel wire extension position measuring units 52a and 52b transmit information about the distance L, which is a measurement result, to the wire guide groove detachment detection unit 53.

[0096] Next, in step S120, a wire guide groove detachment detection step is performed. That is, the wire guide groove detachment detection unit 53 detects the occurrence of a change in the distance L based on the measurement results described above, which were obtained from the parallel wire extension position measuring units 52a and 52b. The wire guide groove detachment detection unit 53 calculates the change in distance L as a difference ΔL. If the difference ΔL exceeds the predetermined reference value, the wire guide groove detachment detection unit 53 transmits information about the difference ΔL to the wire condition determination unit 54.

[0097] Next, in step S130, a wire condition determination step is performed. That is, the wire condition determination unit 54 determines, based on the detection result received from the wire guide groove detachment detection unit 53, whether it is a wire detachment state, in which at least one area of ​​the wire electrode 1 of the parallel wire area 1a has detached from the wire guide groove 51c, or a wire contact state, in which all areas of the wire electrode 1 of the parallel wire areas 1a are in contact with the wire guide grooves 51c. If it is determined that the elongation state of the parallel wire areas 1a has changed, the wire condition determination unit 54 transmits the parallel wire elongation state information ps, which is condition monitoring information, to the machining control 31 of the control unit 300.

[0098] Next, in step S140, the machining process is controlled. Specifically, machining control 31 controls whether to stop or continue the electrical discharge machining (EDM) process based on the parallel wire elongation state information ps, which is the determination result obtained from the wire state determination unit 54. Machining control 31 controls the continuation of the EDM process if the parallel wire elongation state information ps indicates that there is no change in the elongation state of the parallel wire sections 1a, i.e., the elongation state of the cutting wire sections 1b. Machining control 31 controls the termination of the EDM process if the parallel wire elongation state information ps indicates that the elongation state of the parallel wire sections 1a, i.e.,The elongation state of the cutting wire sections 1b has changed. That is, the machining control 31 stops the wire electrical discharge machining simultaneously with the occurrence of the anomalous parallelism of the areas of the wire electrode 1.

[0099] As described above, the wire electrical discharge machining (EDM) machine 1000, according to the first embodiment, can detect an anomalous parallelism condition caused by the wire electrode 1 of the parallel wire section 1a detaching from the wire guide groove 51c immediately after the anomalous parallelism condition occurs. The anomalous parallelism condition is an anomaly in which the multiple sections of the wire electrode 1 of the cutting wire sections 1b, which were originally parallel and equidistant between the pair of wire parallel guide rollers 51a and 51b, are no longer parallel and equidistant. That is, the wire EDM machine 1000 can accurately and promptly detect the positional displacement of the wire electrode 1 and accurately and promptly detect any defect caused by this displacement.The wire electrical discharge machining (EDM) device 1000 can detect anomalous parallelism caused by the detachment of part of the wire electrode 1 area of ​​the parallel wire sections 1a from the wire guide groove 51c immediately after the occurrence of the anomalous parallelism, and the wire EDM process is stopped simultaneously with the occurrence of the anomalous parallelism of the wire electrode 1 area. Therefore, it is possible to prevent the EDM processing of large quantities of thin sheets whose thickness changes during machining, where the distance between the parallel wire electrode 1 area of ​​the parallel wire sections 1a changes during cutting.

[0100] Since the wire EDM machine 1000 stops the cutting process simultaneously with the occurrence of anomalous parallelism in the areas of the wire electrode 1, anomalous areas formed on the surfaces of the thin sheets being cut can be minimized. Consequently, after the parallel state of the parallel wire area 1a is restored, the wire EDM machine 1000 can resume the cutting process from a machining stop position without machining instability, thus improving the machining accuracy of the thin sheets and increasing the yield of thin sheet machining. Therefore, when cutting, for example, a semiconductor block, the wire EDM machine 1000 does not waste expensive semiconductor crystals and can thus reduce wafer production costs.

[0101] Since the wire electrical discharge machining (EDM) device 1000 can also prematurely stop cutting in the anomalous parallelism state of the parallel wire section 1a, it is possible to prevent the formation of a meandering area in the machined groove of the workpiece W, which leads to a reduction in the machining fluid supplied between the electrodes and to an impediment to the discharge of machining waste during cutting, and to prevent the separation of the wire electrode 1.

[0102] Furthermore, the parallel wire extension position measuring units 52a and 52b in the wire electrical discharge machining (EDM) device 1000 include at least one eddy current displacement sensor, one capacitive displacement sensor, one conduction-sensitive sensor, and one touch-sensitive displacement sensor as sensors and measure the distance L with the sensor. Consequently, the wire EDM device 1000 can accurately and promptly detect an anomalous parallelism condition caused by a section of the wire electrode 1 of the parallel wire sections 1a being detached from the wire guide groove 51c immediately after the anomalous parallelism condition occurs.

[0103] Therefore, the wire electrical discharge machining (EDM) device 1000 according to the first embodiment achieves the effect of making it possible to provide a wire EDM device 1000 that is capable of accurately detecting a defect caused by a positional displacement of the wire electrode 1. The wire EDM device 1000 achieves the effect of making it possible to uniformly shape the thickness of the thin plates that are to be cut together from the workpiece W. Second embodiment.

[0104] In a second embodiment, a further function of the wire electrical discharge machining (EDM) device 1000 is described. The wire EDM device 1000, which cuts thin plates using the cutting wire sections 1b, supplies machining power individually from the machining power supply 5 to each of the sections of the wire electrode 1 of the parallel wire sections 1a, which run parallel at a predetermined distance. The machining power is supplied to each section of the wire electrode 1 of the parallel wire sections 1a in pulsed form and only during a predetermined power supply time or voltage application time.

[0105] For example, a pause time, during which no voltage is applied, is defined at a predetermined time interval between a voltage and a voltage applied in pulsed form. Furthermore, to handle a high-frequency pulse oscillation command for supplying machining power to the wire electrode areas 1 of the parallel wire areas 1a, the machining power supply 5 uses a system in which a variety of power supply devices are combined to enable the switch-on and switch-off processes to be carried out in a short time.With such a processing power supply 5, the power supply devices can be damaged by a branch short circuit, in which the power supply in the power supply devices is switched on simultaneously, depending on the time of switching from a switched-off state, in which no processing power is applied to the individual areas of the wire electrode 1 of the parallel wire areas 1a, to a switched-on state, in which processing power is applied to the individual areas of the wire electrode 1 of the parallel wire areas 1a.

[0106] In the wire electrical discharge machining (EDM) machine 1000, to prevent damage to the power supply devices, in addition to a switch-off time during which no power is applied to the wire electrode sections 1 and the parallel wire sections 1a, a time referred to as a dead time is also defined during which the voltage supply to all combined power supply devices is interrupted. The pulsed power supply described above from the machining power supply 5 to each power supply contact 11 or the power supply contact units 6a and 6b is controlled by the machining control 31 and the electrical discharge waveform control 32.

[0107] In the wire electrical discharge machining (EDM) machine 1000, during cutting, a voltage is applied in a pulsed manner between each of the areas of the wire electrode 1 of the parallel wire sections 1a and the workpiece W via the power supply contacts 11, which are connected to the machining power supply via the power supply lines 12a and 12b, thereby generating an electrical discharge. The electrical discharge waveform of the electrical discharge generated between the electrodes, i.e., between the areas of the wire electrode 1 of the cutting wire sections 1b and the workpiece W, varies according to the distance between the electrodes, i.e., between the areas of the wire electrode 1 of the cutting wire sections 1b and the workpiece W at the time the machining power is applied.

[0108] In a state where the areas of wire electrode 1 (cutting wire sections 1b) and the workpiece W are relatively separated from each other at the time the machining power is applied—that is, in a state where the distance between the electrode sections of wire electrode 1 (cutting wire sections 1b) and the workpiece W is relatively large at the time the machining power is applied—an electrical discharge waveform with a relatively low peak is obtained. In a state where the areas of wire electrode 1 (cutting wire sections 1b) and the workpiece W are relatively close together at the time the machining power is applied—that is, in a state where the distance between the areas of wire electrode 1 (cutting wire sections 1b) and the workpiece W is relatively small at the time the machining power is applied—the electrical discharge waveform with a relatively high peak is obtained.In a state where the distance between the areas of the wire electrode 1 of the cutting wire area 1b and the workpiece W is a suitable distance at the time of application of the machining power, an electrical discharge waveform with a mean peak between that in the open state and that in the short-circuit state is obtained.

[0109] Here, the "open state" and the "short-circuit state" are described. When the machining power is applied in pulses between the cutting wire sections 1b and the workpiece W, the magnitude of the electrical discharge pulse to be generated changes according to the distance between the cutting wire sections 1b and the workpiece W. If the distance, i.e., the gap between the electrodes representing the space between the cutting wire sections 1b and the workpiece W, is large, it is less likely that an electrical discharge will occur between the electrodes, and if no electrical discharge occurs, no discharge current flows. Such a state, in which no electrical discharge occurs between the electrodes and no discharge current flows between them, is defined as the "open state."

[0110] In the open state, the electrical discharge voltage waveform essentially maintains the level of the applied voltage during the pulse application time, and the electrical discharge current waveform has a low value. However, depending on the specific resistance of the deionized water used as the processing fluid, i.e., the specific conductivity of the deionized water, and the magnitude of the insulation resistance between the adjacent power supply contacts 11, the electrical discharge current can be detected as a certain leakage current.

[0111] If, however, the cutting wire sections 1b approach the workpiece W extremely closely or come into contact with the workpiece W, an electrical discharge is generated between the electrodes essentially simultaneously with the application of the pulse, and due to the low insulation resistance between the electrodes, a large electrical discharge current flows. Such a condition is defined as a "short-circuit condition".

[0112] In the wire electrical discharge machining (EDM) machine 1000, which uses a process in which the EDM is performed in deionized water, the insulation between the electrodes is ensured by the specific resistance of the deionized water located between them. However, a reduction in the electrode spacing leads to a decrease in the specific resistance between the electrodes, so that a discharge current with low resistance loss, or a current supplied by the machining power supply 5, flows between the electrodes. In this state, the discharge voltage drops sharply, and the discharge current has a waveform with a high peak.

[0113] The "state in which the distance between the wire electrode 1b and the workpiece W is a suitable electrode gap" is classified as a state in which the electrode gap causes neither a short circuit nor an open circuit. Since it is difficult to measure the gap directly during cutting, the wire electrical discharge machining (EDM) device 1000 continuously monitors the states of the resulting discharge waveform.If, in the wire electrical discharge machining device 1000, a tendency to shift from the state in which a discharge state that is neither the open state nor the short-circuit state continues to occur to a state of the "open state" or "short-circuit state" is detected, a stable discharge state is maintained by controlling the machining to adjust various conditions such as the applied voltage, the machining current, the discharge frequency, the pulse duration of the voltage application and the pulse pause.

[0114] The wire electrical discharge machining device 1000 monitors the electrical discharge waveform as described above, estimates the state between the electrodes, i.e., between the areas of the wire electrode 1, the cutting wire areas 1b, and the workpiece W during cutting, and takes over the control of the cutting so that an electrical discharge waveform frequently occurs, leading to stable cutting.

[0115] The machining control 31 transmits command information to the waveform control 32, which controls the oscillation frequency of the discharge pulse during the discharge machining process or the on and off times of the discharge pulse, and controls the discharge energy between the electrodes, i.e., between the wire electrode areas 1 and the cutting wire areas 1b and the workpiece W, from the machining power supply. The machining control 31 transmits command information that controls a machining feed rate to the drive control 34 and controls the distance between the electrodes.

[0116] When machining thin plates with the wire electrical discharge machining (EDM) device 1000 described above, it occasionally happens that the EDM machining continues in a state where the cutting wire areas 1b are completely in contact with the workpiece W, for example when a workpiece W with a relatively high specific resistance, such as a semiconductor wafer material, is used.This situation corresponds to a case in which the processing current flowing through the cutting wire sections 1b, while the cutting wire sections 1b are fully in contact with the workpiece W, does not satisfy the impulse oscillation condition that provides a sufficient amount of heat to melt the wire electrode 1, a case in which a short circuit between the cutting wire sections 1b and the workpiece W occurs partially in one area of ​​the cutting wire sections 1b, but in other areas of the cutting wire sections 1b a normal electrical discharge occurs between the electrodes and thus the electrical discharge cutting continues, or similar, and is due to the fact that it is not possible to accurately observe or correctly determine the situation in which the short circuit persists.

[0117] As described above, the cutting of the thin plates continues in a state where the cutting wire sections 1b and the workpiece W are short-circuited, and the cutting wire sections 1b are in continuous contact with the workpiece W. The cutting process does not continue beyond the positions where the areas of the wire electrode 1 of the cutting wire sections 1b are short-circuited with the workpiece W. Despite this situation, the areas of the wire electrode 1 of the cutting wire sections 1b that are short-circuited with the workpiece W continue to rise while remaining in contact with the workpiece W and are pulled upwards along with the workpiece W by the cutting feed stage 10.

[0118] In the second embodiment, the wire electrical discharge machining device 1000 includes a wire contact machining status monitoring unit 500. Fig. Figure 13 is a schematic diagram illustrating an exemplary configuration of the wire contact processing status monitoring unit 500 of the wire electrical erosion processing device 1000 in the second embodiment. Fig. Figure 13 shows a state in which the electrical discharge machining (EDM) is carried out through the cutting wire section 1b and the wire EDM performed on the workpiece W in a column shape has progressed to a position that corresponds to approximately half the diameter of the workpiece W, with the wire electrode 1 being in contact with the workpiece W and short-circuited. Fig. Figure 13 does not show the thin-plate processing stabilization unit 70 for processing thin plates. Fig. Figure 13 shows the configuration of the wire extension status monitoring unit 400, but this figure is omitted.

[0119] The wire contact processing condition monitoring unit 500 monitors the contact condition between the parallel wire areas 1a and the nozzles 7a and 7b during cutting. Fig. Figure 14 is a block diagram showing exemplary configurations of the control unit 300 and the wire contact machining status monitoring unit 500, which are included in the wire electrical discharge machining (EDM) machine 1000 in the second embodiment. The wire contact machining status monitoring unit 500 includes nozzle contact detection devices 75a and 75b, a wire contact detection circuit switching device 76, and a wire contact determination device 77.

[0120] The nozzle contact detection devices 75a and 75b are connected to the wire contact detection circuit switching device 76 and the nozzles 7a and 7b. The wire contact detection circuit switching device 76 is connected to the nozzle contact detection devices 75a and 75b, the wire contact determining device 77, and the electrical discharge waveform control 32 of the control unit 300. The wire contact determining device 77 is connected to the nozzle contact detection devices 75a and 75b, the power supply lines 12a and 12b, which connect the machining power supply 5 and the power supply contacts 11, or to the machining power supply 5 and the machining control 31 of the control unit 300. The wire contact machining status monitoring unit 500 is thus configured.

[0121] The nozzle contact detection devices 75a and 75b detect characteristic values ​​relating to potential differences between the nozzles 7a and 7b and the power supply contacts 11. In particular, the nozzle contact detection devices 75a and 75b detect a current, voltage, or resistance value in a wire contact detection circuit. The nozzle contact detection devices 75a and 75b transmit information about the current, voltage, or resistance value in the wire contact detection circuit, which represents a detection result, to the wire contact determination device 77.

[0122] The wire contact detection circuit includes the nozzle contact detection devices 75a and 75b, the nozzles 7a and 7b, the cutting wire sections 1b, the power supply contacts 11, the power supply lines 12a and 12b, and the wire contact determining device 77. The wire contact detection circuit is powered by a wire contact detection power supply 74 under the control of the wire contact detection circuit switching device 76.

[0123] The wire contact detection circuit switching device 76 controls the opening and closing of the wire contact detection circuit. The wire contact detection circuit switching device 76 connects the wire contact detection circuit, i.e., closes the wire contact detection circuit, during a machining current off-time when no machining voltage is applied between the electrodes. Furthermore, the wire contact detection circuit switching device 76 disconnects the wire contact detection circuit, i.e., opens the wire contact detection circuit, during a machining current on-time when the machining voltage is applied between the electrodes.

[0124] The wire contact detection device 77 monitors for changes in current, voltage, or resistance in the wire contact detection circuit. When a change in current, voltage, or resistance is detected in the wire contact detection circuit, the wire contact detection device 77 determines that a short-circuit processing continuation condition exists due to the failure to detect contact between the wire electrode areas 1 of the parallel wire areas 1a and the nozzles 7a and 7b, and transmits a signal uc indicating a contact processing condition to the processing control 31.

[0125] Initially, a linear extension state of the cutting wire sections 1b, which are extended between the pair of wire parallel guide rollers 51a and 51b, is maintained in a state in which the cutting wire sections 1b are spaced from the workpiece W between the pair of wire parallel guide rollers 51a and 51b. On the other hand, the wire electrode sections 1 of the cutting wire sections 1b, which are pulled up by the cutting feed stage 10 while in contact with the workpiece W, may come into contact with the nozzles 7a and 7b, with which they should not come into contact. Fig. Figure 13 shows a state in which the areas of the wire electrode 1 of the cutting wire areas 1b, which are lifted by the cutting feed stage 10 while in contact with the workpiece W, come into contact with the nozzles 7a and 7b, with which they should not come into contact.

[0126] Fig. Figure 15 is a characteristic diagram illustrating a point in time of switching between the application of the processing voltage and the wire contact detection of the wire electrical discharge machining device 1000 in the second embodiment. Fig. Figure 15 shows waveforms of a processing power application command pulse and a wire contact detection pulse.

[0127] The processing power application command pulse is a command pulse with which the control for the waveform of the electrical discharge 32 gives a command regarding a time of application of the processing voltage to the processing power supply 5.

[0128] The wire contact detection pulse is a pulsed current supply that provides the wire contact detection circuit with detection current to recognize that contact has been made with the areas of wire electrode 1 of cutting wire area 1b. The wire contact detection pulse oscillates in a phase opposite to that of the machining current application command pulse, which is a command pulse for determining the moment the machining voltage is applied between the electrodes by the machining current supply 5. In other words, the wire contact detection pulse is a wire contact detection switching command pulse for performing the switching between the opening and closing of the wire contact detection circuit.

[0129] When the processing current control pulse is received, which is a command pulse for controlling the timing of the application of the processing voltage by the control for the waveform of the electrical discharge 32, the processing current supply 5 supplies current to each current supply contact 11 based on the processing current control pulse and supplies current to each of the parallel wire sections 1a individually. Consequently, a voltage is applied between the electrodes, i.e., between the cutting wire sections 1b and the workpiece W.

[0130] When the processing current command pulse from the control for the electrical discharge waveform 32 is in the LOW state, the period during which the processing current command pulse is in the LOW state is the processing current off-time P2. During the processing current off-time P2, a processing current off-state occurs in which no current is supplied from the processing current supply 5 to each current supply contact 11 and the processing voltage is not applied between the electrodes, i.e., between the cutting wire areas 1b and the workpiece W.

[0131] If the command pulse for the machining power supply changes to the HIGH state after the machining current off time P2, during which no machining voltage is applied, the period during which the command pulse for the machining power supply is in the HIGH state is the machining current application time P1. During the machining current application time P1, a machining current on state occurs in which current is supplied from the machining power supply 5 to each power supply contact 11 and the machining voltage is applied between the electrodes, i.e., between the cutting wire sections 1b and the workpiece W. In a case where an electrical discharge occurs between the electrodes when the machining current command pulse is in the HIGH state, a machining current is supplied from the machining power supply 5 to the power supply contacts 11.

[0132] During the above-described process of applying a voltage between the electrodes, a command pulse tc is sent from the control unit for the waveform of the electrical discharge 32 to the wire contact detection circuit switching device 76.

[0133] The wire contact detection circuit switching device 76 switches the wire contact detection circuit on during the machining current off time P2 when no machining voltage is applied between the electrodes, i.e., when the machining current application command pulse transmitted by the electrical discharge waveform controller 32 to the machining current supply 5 is in the LOW state. Furthermore, the wire contact detection circuit switching device 76 disconnects the wire contact detection circuit during the machining current on time when the machining current application command pulse transmitted by the electrical discharge waveform controller 32 to the machining current supply 5 is in the HIGH state and the machining voltage is applied between the electrodes, i.e., during the machining current application time P1.

[0134] The processing current off-time P2 corresponds to the period during which the wire contact detection pulse is HIGH. The period during which the wire contact detection pulse is LOW is the detection off-time P3, during which detection power is not applied to the wire contact detection circuit. The period during which the wire contact detection pulse is HIGH is the short-circuit detection time P4, during which detection power is applied to the wire contact detection circuit and the presence or absence of a short circuit between the workpiece W and the cutting wire sections 1b is detected. The period after time T11 is the short-circuit processing resumption time P5, during which cutting is carried out in a state where the cutting wire sections 1b are completely short-circuited to the workpiece W.

[0135] A waveform of the short-circuit processing continuation time P5, during which cutting is performed in a state where the cutting wire sections 1b are completely short-circuited to the workpiece W, is present in the wire contact detection pulse. The wire contact detection pulse has a waveform indicating that the wire contact detection power supply 74 is supplying the wire contact detection circuit with detection current to detect that contact has been made with the wire electrode sections 1 of the cutting wire section 1b.

[0136] If the power supply for detecting a potential change corresponding to the contact state of the cutting wire area 1b with respect to the workpiece W can be continuously applied to the wire contact detection area, the configurations of a resonant circuit and a detection processing system can be simplified. However, since processing power is also applied to the cutting wire area 1b and the workpiece W in addition to the detection power, two types of power—detection power and processing power—are applied to them. Therefore, it is necessary to prevent these two types of voltages, namely detection power and processing power, from being applied to the cutting wire area 1b and the workpiece W simultaneously.

[0137] Therefore, the wire electrical discharge machining (EDM) device 1000 employs a method in which a wire contact detection pulse is applied to the cutting wire sections 1b and the workpiece W during an idle period when no pulsed machining voltage is applied. This prevents the two types of voltage, namely the detection voltage and the machining voltage, from being applied to the cutting wire sections 1b and the workpiece W simultaneously. Since the wire contact detection circuit is only closed when the cutting wire sections 1b are in contact with the workpiece W, the current supplied by the wire contact detection power supply 74 does not flow through the wire contact detection circuit, and no voltage drop occurs. Therefore, the voltage applied to the wire contact detection circuit is in a high state.

[0138] However, when the cutting wire sections 1b come into contact with the workpiece W, the wire contact detection circuit is closed via the conductive workpiece W. In this case, the potentials detected by the nozzle contact detection devices 75a and 75b decrease compared to a case in which there is no contact between the cutting wire sections 1b and the workpiece W, i.e., they are in the LOW state.

[0139] Therefore, with the wire electrical discharge machining device 1000, it is possible to determine, based on the states of the voltages with respect to the potentials detected by the nozzle contact detection devices 75a and 75b, whether the cutting wire areas 1b and the workpiece W are in contact with each other or whether the cutting wire areas 1b and the workpiece W are not in contact with each other, for example, whether an impulse voltage applied to the wire contact detection circuit is in the HIGH state or in the LOW state, as in Fig. 15 shown.

[0140] In a normal electrical discharge machining (EDM) state, the cutting wire sections 1b are not in contact with the nozzles 7a and 7b, and thus the wire contact detection circuit is open. On the other hand, as described above, if no contact is detected between the cutting wire sections 1b and the workpiece W, the machining feed is continued by the control for the drive of the cutting stage 34, so that the raised cutting wire sections 1b come into contact with the metal nozzles 7a and 7b, thereby closing the wire contact detection circuit.

[0141] When the wire contact detection circuit is connected by the wire contact detection circuit switching device 76, the wire contact determination device 77 detects a change in the current, voltage, or resistance value in the wire contact detection circuit. The wire contact determination device 77 detects the change in the current, voltage, or resistance value of the wire contact detection circuit by comparing the current, voltage, or resistance value in the wire contact detection circuit, detected when the wire contact detection circuit is closed by the wire contact detection circuit switching device 76, with a predetermined determination reference value of the current, voltage, or resistance value.

[0142] The predetermined determination reference value of the current value, voltage value or resistance value is a current value, a voltage value or a resistance value of the wire contact detection circuit in a state in which the cutting wire sections 1b, which have come into contact with the workpiece W and have been pulled upwards, are in contact with the metal nozzles 7a and 7b.

[0143] In a case where the current value, voltage value or resistance value in the wire contact determining circuit that has been detected exceeds a determination reference value corresponding to the value, the wire contact determining device 77 determines that a change in the current value, voltage value or resistance value has occurred and determines that the change in the current value, voltage value or resistance value of the wire contact determining circuit has been detected.In a case where the current value, voltage value or resistance value in the wire contact detection circuit that has been detected does not exceed the determination reference value corresponding to the value, the wire contact detection device 77 determines that there is no change in the current value, voltage value or resistance value and determines that the change in the current value, voltage value or resistance value of the wire contact detection circuit has not been detected.

[0144] Upon detecting a change in the current, voltage, or resistance value of the wire contact detection circuit, the wire contact detection device 77 determines that a short-circuit processing continuation state is in place, in which cutting is performed while the workpiece W and the cutting wire section 1b are short-circuited due to the failure to detect a contact, i.e., due to the fact that no contact has been detected between the areas of the wire electrode 1, the parallel wire sections 1a, and the nozzles 7a and 7b. The short-circuit processing continuation state can be reformulated as a contact processing state in which cutting is performed while the workpiece W and the cutting wire section 1b are in contact with each other. The wire contact detection device 77 then transmits the signal uc, indicating the contact processing state, to the processing control 31.

[0145] Upon receiving the signal uc, which indicates the contact processing status, the processing control 31 instructs the control for the electrical discharge waveform 32 to stop the oscillation of the processing power supply 5, the wire feed control 35 to stop the wire feed, and the control for the drive of the cutting stage 34 to stop the cutting feed stage 10 based on the signal uc. That is, the processing control 31 controls the termination of the voltage application between the electrodes, the termination of the wire electrode 1's travel, and the termination of the movement of the cutting feed stage 10 and the workpiece W based on the signal uc, thus ending the cutting process.

[0146] The wire contact detection power supply 74 applies the detection power to the wire contact detection circuit, so that the detection power is not applied simultaneously with the machining power supplied between the electrodes by the machining power supply 5. That is, the wire contact detection power supply 74 supplies the wire contact detection circuit with the wire contact detection power via the wire contact detection pulse.

[0147] If the wire contact detection circuit is connected, even briefly, in a state where machining power is applied between the electrodes by the machining power supply 5, machining power will also be applied to the wire contact detection circuit from the power supply contacts 11 or the power supply lines 12a and 12b, and the device forming the wire contact detection circuit may be damaged. Alternatively, if the wire contact detection circuit is connected, even briefly, in a state where machining power is applied between the electrodes, the detection power for the machining power application command pulse will be applied between the electrodes, and the electrical discharge machining may become unstable.

[0148] Therefore, in the wire contact detection power supply 74, not only is the oscillation carried out in a phase opposite to that of the machining power application command pulse, but a period is also defined in which neither the machining power command pulse nor the wire contact detection pulse is in the switched-on state, namely a period of several hundred nanoseconds, which is designated Δt1 and lies immediately after the change of the machining power command pulse from HIGH to LOW, and a period of several hundred nanoseconds, which is designated Δt2 and lies immediately before the change of the machining power command pulse from LOW to HIGH, as in Fig. 15 shown.

[0149] The pulse for applying the machining power, sent by the control unit for the waveform of the electrical discharge 32 to the machining power supply 5, is also sent to the wire contact detection circuit switching device 76. The wire contact detection circuit switching device 76 responds to the machining power application command pulse and opens and closes the wire contact detection circuit based on the time of application of the pulse voltage from the machining power supply 5 to the power supply contacts 11.

[0150] Fig. Figure 16 is a schematic diagram showing an example of a state in which the parallel wire section 1a is detached from the wire guide groove 51c in the wire parallel guide roller 51a of the wire electrical discharge machining device 1000 in the second embodiment. Fig. Figure 16 shows a longitudinal section through the rotating shaft 51a2 of the wire parallel guide roller 51a with respect to the nozzle 7a, the parallel wire sections 1a extended between the wire parallel guide rollers 51a and 51b, and the wire parallel guide roller 51a. Furthermore, it shows Fig. 16 a state in which cutting continues while part of the areas of the wire electrode 1 of the parallel wire sections 1a is in contact with the workpiece W, thereby raising the parallel wire section 1a extending in the wire guide groove 51c and possibly bringing it into contact with the nozzle 7a, and cutting continues to cut the nozzle 7a. Fig. 16 is the parallel wire section 1a, which is to be replaced by the wire guide groove 51c, marked by an open circle.

[0151] Fig. 17 is a concept diagram that represents a detection value corresponding to the wire detachment state in Fig. Figure 16 illustrates the determination of a state according to the detection value. The detection value D is a current value, a voltage value, or a resistance value in the wire contact detection circuit when the wire contact detection circuit is connected by the wire contact detection circuit switching device 76. Fig. Figure 17 schematically shows a monitored situation regarding the behavior of the parallel wire section 1a, which extends from the wire guide groove 51c in Fig. 16 solved, based on a detection value in the wire contact processing status monitoring unit 500 of the wire electrical erosion processing device 1000.

[0152] In Fig. 16. In the stationary state, the parallel wire sections 1a fit into the deepest areas of the wire guide grooves 51c, and a normal cut is performed (state A). Subsequently, a situation arises in which a portion of the wire electrode 1 sections of the parallel wire sections 1a is short-circuited with a machined surface of the workpiece W, and the cutting continues in a state where this portion of the wire electrode 1 sections of the parallel wire sections 1a is in continuous contact with the machined surface of the workpiece W. As a result, the wire electrode 1 section enters an anomalous elongation state in which it begins to rise out of the wire guide groove 51c (state B), while the cutting feed stage 10 of the workpiece W is in contact with the portion of the wire electrode 1 sections of the parallel wire section 1a.If the cutting process continues without eliminating the anomalous elongation condition, the raised area of ​​the wire electrode 1 may come into contact with the nozzle 7a (state C). If the cutting process continues, the area of ​​the wire electrode 1 that has come into contact with the nozzle 7a will rub against and cut the nozzle 7a, forming a cut groove Wz in the nozzle 7a. If state C continues, the wire electrode 1 will separate.

[0153] A similar phenomenon to the one described above occurs in the nozzle 7b, the parallel wire sections 1a extended between the wire parallel guide rollers 51a and 51b and the wire parallel guide roller 51b.

[0154] In Fig. 17. State A, which is a stable state in which there is no anomaly in the wire elongation state, transitions via state B to state B in which the area of ​​the wire electrode 1 is in contact with the nozzle 7a. At this point, the detection value D in the wire contact processing state monitoring unit 500 changes from a detection value D1 in the stable state to a detection value D2, whereby the wire contact detection device 77 detects the occurrence of state C, which is the wire contact state with respect to the nozzle 7a. The wire contact detection device 77 detects the occurrence of state C based on the detection value obtained from the nozzle contact detection device 75a when the wire contact detection circuit is switched by the wire contact detection circuit switching device 76.

[0155] The wire contact determining device 77 transmits the signal uc, which indicates the contact processing status, to the processing control 31. The processing control 31 instructs the control for the waveform of the electrical discharge 32 to stop the oscillation of the processing power supply 5, the wire feed control 35 to stop the wire feed, and the control for the drive of the cutting stage 34 to stop the cutting feed stage 10 based on the signal uc.Alternatively, upon receiving the signal uc indicating the contact processing state from the wire contact determining device 77, the processing control 31 instructs the control for the waveform of the electrical discharge 32 to temporarily stop the oscillation of the processing power supply 5 or to perform an oscillation frequency control to rapidly reduce the oscillation frequency of the processing power supply 5, or instructs the wire feed control 35 to reverse the feed direction of the wire electrode 1 from the cutting progress direction by the control for the drive of the cutting stage 34 and to rapidly retract the cutting feed stage 10 (state D in the . Fig. 16 and Fig. 17). That is, based on the signal uc, the machining control 31 initiates a retraction operation to eliminate a short circuit, in which the feed direction of the control for driving the cutting stage 34 is reversed from the cutting progress direction. Consequently, the wire electrical discharge machining device 1000 can retract the abnormally elongated portion of the wire electrode 1 into the wire guide groove 51c without interrupting the cutting process.

[0156] If the retraction operation to eliminate the short circuit is not carried out based on the signal uc, the processing control 31 also stops the power supply to all parallel wire sections 1a and stops the cutting. Consequently, the processing control 31 can stop the cutting simultaneously with the occurrence of the anomalous parallelism of the wire electrode sections 1.

[0157] As described above, according to the second embodiment, it is possible to detect when a section of the wire electrode 1 of the parallel wire sections 1a has detached from the wire guide groove 51c and is in contact with the nozzles 7a and 7b, and to stop the cutting process when this section of the wire electrode 1 comes into contact with the nozzles 7a and 7b. Consequently, according to the second embodiment, it is possible to prevent peripheral components of the wire electrical discharge machining (EDM) device 1000, such as the nozzles 7a and 7b, from being damaged by friction with the wire electrode 1.

[0158] According to the second embodiment, when the portion of the wire electrode 1 that has detached from the wire guide groove 51c comes into contact with the nozzles 7a and 7b, the wire electrode 1 is prevented from detaching by controlling the vibration of the processing power supply 5. That is, the wire electrical discharge machining (EDM) machine 1000 performs a control operation to temporarily stop the vibration of the processing power supply 5, or a vibration frequency control operation to rapidly reduce the vibration frequency of the processing power supply 5, when the portion of the wire electrode 1 that has detached from the wire guide groove 51c comes into contact with the nozzles 7a and 7b, thereby preventing the wire electrode 1 from detaching due to the cutting operation continuing in the contact machining state.

[0159] According to the second embodiment, the portion of the wire electrode 1 that has detached from the wire guide groove 51c is retracted from the wire contact state by the drive control of the cutting feed stage 10 when it comes into contact with the nozzles 7a and 7b. Therefore, the portion of the wire electrode 1 that has elongated abnormally can be returned to the wire guide groove 51c without interrupting the cutting process.

[0160] According to the second embodiment, the machining performed while the area of ​​the wire electrode 1 is in contact can be minimized, and anomalous areas formed on the surfaces of the thin plates to be cut can be minimized because the wire electrical discharge machining (EDM) machine 1000 stops cutting simultaneously with the occurrence of anomalous parallelism in the areas of the wire electrode 1. Consequently, the wire EDM machine 1000 can resume machining after the elongation of the areas of the wire electrode 1 in the anomalous elongation state is restored and power is re-established to the wire electrode 1, resuming the cut from the machining stop position without machining instability, improving the machining accuracy of the thin plates, and increasing the yield of thin plate machining.Therefore, the wire electrical discharge machining (EDM) machine 1000 does not waste expensive semiconductor crystals when cutting, for example, a semiconductor block, and can thus reduce the production costs for wafers.

[0161] According to the second embodiment, cutting of the workpiece W is prevented by friction in the area of ​​the wire electrode 1 that comes into contact with the workpiece W. This prevents the formation of a meandering section of the machined groove in the workpiece W, which would reduce the amount of machining fluid supplied between the electrodes, impede the removal of machining debris during cutting, and prevent wire breakage. Consequently, the wire electrical discharge machining (EDM) device 1000 does not waste expensive semiconductor crystals when cutting a semiconductor block, improves the yield when machining thin wafers, and thus reduces wafer production costs.

[0162] Therefore, the second embodiment achieves the effect of providing a wire electrical discharge machining (EDM) device 1000 capable of accurately detecting defects caused by positional displacement of the wire electrode 1. Furthermore, the second embodiment enables the uniform thickness of the thin plates to be cut together from the workpiece W. Finally, the second embodiment prevents damage to the components within the wire EDM device 1000 caused by the wire electrode 1 in a short-circuit state.

[0163] Next, the respective hardware configurations of a control unit 80 according to the first and second embodiments are described. The control unit 80 according to the first and second embodiments corresponds in each case to the control unit 300 and the wire extension status monitoring unit 400 in the first and second embodiments, and to the wire contact processing status monitoring unit 500 in the second embodiment. Each function of the control unit 80 according to the first and second embodiments is implemented by a processing circuit. The processing circuit can be dedicated hardware or a processing device that executes a program stored in a memory device.

[0164] In a case where the processing circuit is dedicated hardware, the processing circuit corresponds to a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an application-specific integrated circuit, a field-programmable gate array, or a combination thereof. Fig. Figure 18 is a diagram illustrating a configuration in which each function of the control unit according to the first and second embodiments is implemented by hardware. A logic circuit 81a for implementing functions of the control unit 80 is contained in a processing circuit 81.

[0165] In a case where the processing circuit 81 is a processing device, the functions of the control unit 80 are implemented by software, firmware or a combination of software and firmware.

[0166] Fig.Figure 19 is a diagram illustrating a configuration in which each function of the control unit according to the first and second embodiments is implemented by software. The processing circuit 81 includes a processor 811, which executes a program 81b, a working memory 812, which is used by the processor 811 as a workspace, and a storage device 813, which stores the program 81b. The functions of the control unit 80 are implemented by the processor 811 extending the program 81b, stored in the storage device 813, to the direct-access memory 812 and executing it. The software or firmware is described in a programming language and stored in the storage device 813. For example, a central processing unit (CPU) can serve as the processor 811, but there is no restriction on this.The storage device 813 can be a semiconductor memory such as random-access memory (RAM), read-only memory (ROM), flash memory, erasable programmable read-only memory (EPROM), or electrically erasable programmable read-only memory (EEPROM (registered trademark)). The semiconductor memory can be non-volatile or volatile. In addition to semiconductor memory, a magnetic disk, flexible disk, optical disk, compact disc, mini-disc, or digital versatile disc (DVD) can also be used as the storage device 813. It should be noted that the processor 811 can output data, such as a calculation result, to the device 813 and store the data therein, or it can store the data via the random-access memory 812 in an additional device (not shown).By integrating the 811 processor, the 812 direct access memory and the 813 storage device into one chip, the functions of the 80 control unit can be implemented by a microcomputer.

[0167] The processing circuit 81 implements the functions of the control unit 80 by reading and executing the program 81b stored in the memory device 813. In other words, the program 81b instructs a computer to execute procedures and methods for implementing the functions of the control unit 80.

[0168] The processing circuit 81 can implement one area of ​​the functions of the control unit 80 through dedicated hardware and another area of ​​the functions of the control unit 80 through software or firmware.

[0169] Thus, the processing circuit 81 can implement the functions described above through hardware, software, firmware or a combination thereof.

[0170] The configurations described in the above embodiments are merely examples and can be combined with other known technologies; the embodiments can be combined with one another, and a range of configurations can be omitted or modified without deviating from the essentials. List of reference symbols

[0171] 1 Wire electrode; 1a Parallel wire section; 1b Cutting wire section; 2, 2a, 2b, 2c, 2d Guide roller; 2e, 5c Wire guide groove; 3, 3a, 3b Spool; 4a, 4b Damping guide roller; 5 Machining power supply; 6a, 6b Power supply contact unit; 7a, 7b Nozzle; 7c Machining fluid discharge opening; 8a, 8b Spool rotation control; 9a, 9b Cross control device; 10 Cutting feed stage; 11 Power supply contact; 12a, 12b Power supply line; 31 Machining control; 32 Electrical discharge waveform control; 34 Cutting stage drive control; 35 Wire feed control; 42 Workpiece mounting plate; 43 Level; 51a, 51b Wire parallel guide roller; 51a1 upper end area; 51a2 rotating shaft; 51d outer circumferential surface; 52a, 52b parallel wire extension position measuring unit; 52a1, 55a1 surface; 53 wire guide groove detachment detection unit; 54 wire condition determination unit; 55a, 55b guide roller holder; 62 machining fluid supply line;70 Thin plate machining stabilization unit; 71, 71a, 71b Machining fluid flow compensation plate; 72 Workpiece holding unit; 74 Wire contact detection power supply; 75a, 75b Nozzle contact detection device; 76 Wire contact detection circuit switching device; 77 Wire contact determining device; 100 Machining mechanism unit; 101, 102, 103 Arrow; 200 Power supply unit; 300 Control unit; 400 Wire extension status monitoring unit; 500 Wire contact machining status monitoring unit; 1000 Wire electrical discharge machining device; L, L1, L2, L3 Distance; P1 Machining current application time; P2 Machining current switch-off time; W Workpiece; Wz Cutting groove.; QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2017-87395 A

[0004]

Claims

[1] Wire electrical discharge machining (EDM) device which generates an electrical discharge between a plurality of running cutting wire sections and a workpiece in order to perform EDM machining of the workpiece with the energy generated by the electrical discharge and simultaneously cut a plurality of wafers from the workpiece, wherein the wire EDM device comprises: a wire electrode comprising a multitude of parallel, spaced-apart cutting wire areas and an area facing the workpiece; a power supply unit for generating an electrical discharge between the multitude of cutting wire areas and the workpiece; a pair of wire parallel guide rollers arranged on both sides of the workpiece to hold the workpiece between each other, each of these rollers having a plurality of wire guide grooves formed at equal intervals on its outer circumferential surface, the plurality of wire guide grooves causing the plurality of cutting wire areas to run appropriately therein and restricting the movement of the plurality of cutting wire areas; a parallel wire extension position measuring unit for measuring the distance between a measuring reference surface set parallel to a virtual plane containing the plurality of cutting wire areas and the wire electrode forming the plurality of cutting wire areas; a wire guide groove detachment detection unit for detecting the occurrence of a change in distance based on a measurement result obtained from the parallel wire extension position measuring unit; a wire condition determination unit for determining whether a wire detachment state exists, in which at least one of the cutting wire sections has detached from the wire guide groove, or a wire contact state exists, in which all cutting wire sections are in contact with the wire guide grooves, based on a detection result obtained from the wire guide groove detachment detection unit; and a processing control unit for controlling the stop or continuation of the electrical discharge processing based on a determination result obtained from the wire condition determination unit. [2] Wire electrical discharge machining device according to claim 1, wherein the parallel wire extension position measuring unit includes at least one eddy current displacement sensor, one capacitive displacement sensor, one conductivity-sensitive sensor and one touch-sensitive displacement sensor and measures the distance. [3] Wire electrical discharge machining device according to claim 1 or 2, wherein the machining control unit stops the electrical discharge machining in a case where the wire condition determination unit determines that the wire detachment state is present. [4] Wire electrical discharge machining device according to one of claims 1 to 3, wherein The power supply unit comprises a processing power supply and a power supply contact that is connected to the cutting wire area to supply power from the processing power supply to the cutting wire area. The wire electrical discharge machining (EDM) device includes the following: a nozzle positioned above the plurality of cutting wire areas to supply a machining fluid into a gap between the cutting wire area and the workpiece, wherein the plurality of cutting wire areas are located between the wire parallel guide roller and the nozzle, and the nozzle is spaced apart from the plurality of cutting wire areas; and a wire contact detection circuit for detecting a contact between the nozzle and the cutting wire area based on a potential difference between the nozzle and the power supply contact, and The processing control unit stops the electrical discharge machining in a case where a contact between the nozzle and the cutting wire area is detected in the wire contact detection circuit. [5] Wire electrical discharge machining apparatus according to claim 4, comprising the following: a cutting feed stage for changing the relative positions of the workpiece and the cutting wire area, wherein The machining control unit stops the power supply to all cutting wire areas and the electrical discharge machining if a contact between the nozzle and the cutting wire area is detected and no retraction operation is performed to eliminate a short circuit, in which the feed direction of the cutting feed stage is reversed from the cutting progress direction of the workpiece. [6] A wire electrical discharge machining (EDM) process in which an electrical discharge is generated between a plurality of moving cutting wire sections and a workpiece in order to subject the workpiece to EDM machining with the energy generated by the electrical discharge and simultaneously cut a plurality of wafers from the workpiece, wherein the wire electrical discharge machining process comprises the following steps: a step for measuring the parallel wire extension position, in which the distance between a measurement reference surface set parallel to a virtual plane containing the plurality of cutting wire areas and a wire electrode forming the plurality of cutting wire areas is measured; a step for detecting a detachment from the wire guide groove, in which the occurrence of a change in distance is detected based on a measurement result obtained in the step for measuring the parallel wire extension position; a wire state determination step to determine whether it is a wire detachment state, in which at least one of the cutting wire sections has detached from the wire guide groove, or a wire contact state, in which all cutting wire sections are in contact with the wire guide grooves, based on a detection result obtained in the wire detachment detection step; and a processing step to control the stop or continuation of the electrical discharge machining process based on the determination result obtained in the wire condition determination step. [7] A wire electrical discharge machining (EDM) method according to claim 6, wherein in the machining step the power supply to all cutting wire areas is interrupted and the EDM machining is stopped when contact between a nozzle and the cutting wire area is detected and no retraction operation is performed to eliminate a short circuit, in which the feed direction of a cutting feed stage that changes the relative positions of the workpiece and the cutting wire area is reversed from the cutting progress direction of the workpiece, the nozzle is arranged at a position above the plurality of cutting wire areas and supplies a machining fluid into a gap between the cutting wire area and the workpiece, in a state in which the plurality of cutting wire areas are received between a pair of wire parallel guide rollers and the nozzle, and in a statein which the nozzle is spaced apart from the plurality of cutting wire sections, wherein the pair of wire parallel guide rollers is arranged on both sides of the workpiece to hold the workpiece between each other, wherein a plurality of wire guide grooves are formed at equal intervals on an outer circumferential surface of each of the two wire parallel guide rollers, wherein the plurality of wire guide grooves cause the plurality of cutting wire sections to fit into them and restrict the movement of the plurality of cutting wire sections. [8] Method for producing wafers in which a plurality of wafers are simultaneously cut out of the workpiece by the wire electrical discharge machining process according to claim 6 or 7. [9] Method for producing wafers according to claim 8, wherein the workpiece is a semiconductor block and the wafer is a semiconductor wafer.

Images