JP5491161B2 - Wire for electric discharge machining and multi-electric discharge machining method - Google Patents

Description

  The present invention relates to a wire electric discharge machining that cuts a workpiece by electric discharge energy, and in particular, an electric discharge machining wire suitable for unidirectional machining, and a plurality of places on the workpiece using the electric discharge machining wire. The present invention relates to a multi-electric discharge machining method for simultaneously performing electric discharge cutting in a parallel direction.

  Wire electric discharge machining is a machining method in which a thin wire is used as an electrode wire, a voltage is applied between the electrode wire (wire) and the workpiece, and the workpiece is cut by heat generated by electric discharge. In this processing, while the electrode wire is continuously run in a tensioned state, a voltage is applied between the electrode wire and the workpiece (for example, a die or a die) in a working fluid atmosphere, and the workpiece and the electrode are applied. A pulsed discharge is repeatedly generated between the wires. At that time, in order to generate a stable discharge, a gap (distance between the electrodes) of several microns to several tens of microns, that is, a discharge gap is required between the electrode wire and the workpiece, and the discharge voltage and discharge current during processing are required. Control is performed to keep the discharge gap properly by moving the workpiece forward and backward in the machining direction on the order of sub-millisecond while monitoring. Water or oil with high purity is used as the processing liquid. Then, electric discharge machining is performed while the machining liquid is supplied to the discharge site or in the machining liquid.

  Electric discharge machining includes melting, explosion, scattering, cooling, and sludge removal processes. Then, when the electrode wire and the workpiece are continuously approached, the electric discharge machining is repeatedly performed, and the workpiece is machined into a predetermined shape. The electrode wire used generally has a wire diameter of about 0.2 mm. In the fine processing, an electrode wire having a thin wire diameter of 100 μm or less (0.01 to 0.1 mm) is used.

  FIG. 6 is a cross-sectional view (a) to (c) perpendicular to the wire longitudinal direction of a conventional representative electric discharge machining wire.

  A conventional electric discharge machining wire 1 shown in FIG. 6A is a wire made of only a base material 11, and is, for example, a brass wire, a tungsten wire, a molybdenum wire, or the like. A brass wire is generally used for a wire having a relatively large diameter. The brass wire has high electrical conductivity, so heat generation during discharge is small and discharge characteristics are excellent. However, since brass wire is not strong (tensile strength), it cannot be used for electrode wires having a small wire diameter. Therefore, tungsten wires and molybdenum wires having high strength (tensile strength) at high temperatures are used for those having a small wire diameter, particularly electrode wires having a wire diameter of 100 μm or less for fine processing. However, tungsten wires and molybdenum wires have problems in price and manufacturability.

  Further, the conventional electric discharge machining wire 2 shown in FIG. 6B is obtained by forming a metal layer 13 on the surface of a base material 11 by plating or modification. For example, a steel wire (piano wire) is used as the base material 11. ) And a metal layer 13 formed with a brass plating layer or the like (see, for example, Patent Document 1) is known. By forming a metal layer on the surface by plating or the like, the drawability is improved.

  Further, in the conventional electric discharge machining wire 3 shown in FIG. 6C, a metal layer 13 is formed on the surface of the base material 11 by plating or reforming, and more electric than the base material 11 is formed on the substantially entire outermost surface. A high resistance layer 14 having high resistance is formed. For example, a steel wire (piano wire) is used as the base material 11, a brass plating layer is formed as the metal layer 13, and an alkyd is used as the outermost high resistance layer 14. Resins such as resins, polyethylene resins and polyester resins, and those provided with a non-insulating high-resistance layer such as metal carbide (for example, see Patent Document 2) are known. The wire having such a configuration can stably generate a discharge with a small discharge gap. Also, by optimizing the inter-pole servo control (servo voltage value control) using a wire electric discharge machine, the discharge gap can be reduced and the machining surface can be smoothed, and the machining groove width can be reduced. In addition, the number of discharges can be increased to increase the processing speed, and the processing efficiency of fine processing can be increased.

  Wire electric discharge machining has been originally used for the manufacture of articles having various curved surfaces, and has conventionally been favorably used for forming complex machining surfaces. In recent years, however, wire electric discharge machining has been studied for use in not only complicated shape machining but also slicing of hard and brittle materials such as Si and SiC compound semiconductors because of improved machining performance.

  As a wire electric discharge machining method for slicing such compound semiconductors, etc., an electric discharge machining wire is supplied from a supply reel, wound multiple times at equal intervals between rollers, wound around a discharge reel, and between the rollers of the wire The work piece is caused to generate a discharge by applying a voltage from the power supply area side via a power supply while bringing the work piece from the discharge area side close to a plurality of wire portions running in parallel with each other. So-called multi-electric discharge machining (see, for example, Patent Documents 3 and 4) is known in the past.

JP 2006-136852 A JP 2008-296350 A Japanese Patent Laid-Open No. 9-248719 JP 2000-107941 A

  However, the conventional wire for electric discharge machining is not suitable for machining in which the machining direction is specified in one direction (hereinafter referred to as unidirectional machining), such as slicing machining of a compound semiconductor or the like.

  There is a difference in required machining performance between electric discharge machining for forming a complicated machining surface and simple slit machining such as slicing machining of a compound semiconductor or the like.

  In other words, in the electric discharge machining for forming a complex machining surface, the direction in which it advances by electric discharge (hereinafter referred to as the machining direction) changes every moment in order to obtain a complicated machining surface. On the other hand, the circumferential position of the wire surface facing the processing direction changes every moment. Therefore, a wire used for electric discharge machining for obtaining such a complicated machining surface is required to have uniform machining performance over the entire surface of the wire. If the machining direction is unspecified, stable machining cannot be performed unless the electrical discharge machining performance is uniform over the entire surface of the wire.

  On the other hand, in the case of unidirectional machining, the fact that the wire surface has a uniform machining performance over the entire surface, as in the case of conventional electric discharge machining wires, is rather harmful. In the case of unidirectional machining, it is only necessary to discharge in a specific machining direction, but in the case of using a conventional wire for electric discharge machining, not only in the machining direction but also from both sides in the width direction to the machining direction. Discharge occurs in a wide range. Such a discharge in a direction other than the machining direction is not only a useless discharge that does not directly contribute to the machining but is also harmful. Unnecessary electric discharge in directions other than the machining direction roughens the machining surface and increases the machining groove width.

  In electric discharge machining, the workpiece is melted, exploded, and scattered. The large processing groove width means that there is a large amount of melting, explosion and scattering. That is, the machining groove width greatly affects the yield of the workpiece. In particular, in the case of multi-electric discharge machining, since the influence of the machining groove width is large, it is required to make the machining groove width as small as possible. For example, in the case of multi-electric discharge machining in which several tens or hundreds of Si wafers are sliced at a time, a slight increase in the machining groove width greatly reduces the yield.

As a wire for electric discharge machining used for unidirectional machining such as slicing of compound semiconductors, etc., it is possible to efficiently generate electric discharge that contributes to unidirectional machining to realize high-speed machining, and to unidirectional machining. It is required that the generation of useless discharge that does not contribute can be suppressed, the formation of a smooth processed surface can be realized, and the processing groove width can be reduced to improve the yield of the workpiece.

  Therefore, as a wire for electric discharge machining having the machining performance required for unidirectional machining, the wire surface has a discharge area continuous in the longitudinal direction of the wire at the same peripheral edge of the wire cross section, and a non-discharge having a higher electric resistance than the discharge area. A wire for electric discharge machining having a region is conceivable. By configuring the wire for electric discharge machining in this way, it can be expected that a portion to be discharged on the surface of the wire is specified in the circumferential direction, and electric discharge can be efficiently generated only in the machining direction of one-way machining.

  The fact that the surface of the wire has a uniform processing performance over the entire surface like a conventional wire for electric discharge machining is inconvenient in unidirectional processing such as slicing processing of compound semiconductors and the like, and is unnecessary in other than the processing direction. Electric discharge occurs, and the useless discharge roughens the machined surface and increases the machining groove width, resulting in a decrease in the yield of the workpiece. Especially in multi-electric discharge machining, due to an increase in the machining groove width. The decrease in yield increases. On the other hand, according to the wire for electric discharge machining in which the wire surface has a discharge region continuous in the longitudinal direction of the wire at the same peripheral edge of the wire cross section and a non-discharge region having a higher electric resistance than the discharge region, In this way, the discharge part on the surface of the wire is specified in the circumferential direction, so that the discharge can be generated efficiently only in the machining direction, and the part where the workpiece is melted and removed is minimized. Thus, the yield can be improved.

  However, the electric discharge machining wire in which the wire surface is composed of a discharge region and a non-discharge region in this way cannot supply power in the non-discharge region, and therefore must supply power in the discharge region. If the discharge area of the same part of the wire approaches the multiple points of the workpiece and repeats the discharge several times as in multi-discharge machining, the surface of the discharge area becomes rough and stable power supply cannot be performed. Therefore, the electric discharge becomes unstable, and the electric discharge cutting process on the outgoing line side becomes difficult.

  Therefore, it is possible to efficiently generate electric discharge only in the machining direction, to minimize the portion where the workpiece is melted and removed, to improve the yield, and to perform stable power feeding The challenge is to make it possible.

The above-described problem is that, on the wire surface, one discharge region continuous in the wire longitudinal direction at the same peripheral edge of the wire cross section, at least two non-discharge regions continuous in the wire longitudinal direction on both sides in the circumferential direction of the discharge region, A wire for electric discharge machining having a power supply region continuous in the longitudinal direction of the wire separated from the discharge region by the discharge region , in particular, the core material part forms a metal layer on the surface of the base material, and further, the base material on the outermost surface A high-resistance layer having a higher electrical resistance is formed, and the high-resistance layer is exposed on the wire surface in an arrangement opposite to the wire cross section, and the region of the wire surface where the high-resistance layer is exposed is electrically connected to the discharge area A region formed between the discharge region and the power supply region is covered with an insulating layer having a higher electrical resistance than the high resistance layer on the wire surface to form a non-discharge region. For electric discharge machining It can be solved by ear.

  In this wire for electric discharge machining, the power supply area is separated from the discharge area by the non-discharge area on the wire surface, and the discharge area can be dedicated to discharge and the power supply area can be dedicated to power supply. Therefore, the discharge area of the same part of the wire approaches the multiple points of the workpiece one after another and repeats the discharge many times as in multi-discharge machining. Therefore, even when the discharge area is rough, stable power feeding can be performed. And since this wire for electric discharge machining specifies the discharge part on the surface of the wire in the circumferential direction, in wire electric discharge machining that specifies the machining direction in one direction, the electric discharge can be efficiently generated only in the machining direction. And the yield can be improved by minimizing the portion where the workpiece is melted and removed.

  In this electric discharge machining wire, the “non-discharge area” is formed of an insulating layer such as a resin having a higher electric resistance than the “discharge area”. The term “insulating layer” as used herein means a layer that does not conduct electricity at a voltage during normal use, specifically at a voltage of 50V to 300V.

Further, the "electric resistance" refers to electrical resistance from the base metal surface of the wire until the wire outermost surface. The “ high resistance layer ” refers to a layer that avoids concentrated discharge and enhances dispersive discharge characteristics at a voltage in normal use, specifically, a voltage of 50 to 300 V (metal oxide layer (for example, zinc oxide layer)) Or a resin layer (for example, a layer formed of an alkyd resin, a polyethylene resin, a polyester resin, etc., and formed to a thickness of 0.1 to 5 μm), or any other similar material, and is not particularly limited.

  Further, the wire for electric discharge machining may be formed of the same material in the “discharge area” and the “non-discharge area”. For example, if a resin such as polyester or polyethylene is thinly formed on the wire surface (for example, 1 μm), a non-insulating high-resistance layer is formed, and a discharge region is formed. If the same resin is formed thick (for example, 10 μm), an insulating layer is formed. A non-discharge region is formed.

  In the electric discharge machining wire, it is preferable that the discharge region, the non-discharge region, and the power supply region are arranged symmetrically with respect to an axis of symmetry passing through the discharge region and the power supply region in the wire cross section. By setting it as such an arrangement | positioning, it becomes the arrangement | positioning which the discharge area and the electric power feeding area opposed, and the electric power feeding area moves away from a discharge area, and the unnecessary discharge from an electric power feeding area is suppressed.

  Further, the wire for electric discharge machining has a pair of straight portions that are long in one direction and extend in the longitudinal direction so as to face each other, and connect the opposite ends of both ends of the pair of straight portions. It is preferable that the wire has a curved portion that bulges outward in at least one of the portions, and the curved portion has a discharge area in one of the curved portions that are continuous in the longitudinal direction of the wire. In particular, the shape of the wire cross section is a track shape in which a pair of straight portions are the same size and parallel to each other, and both ends of the pair of straight portions have curved portions at both ends that face each other. It is good.

The electric discharge machining wire has a structure in which the cross-sectional shape is long in one direction and has a discharge region in the curved portion at one end in the longitudinal direction of the cross section, thereby increasing the tensile strength without increasing the width of the machining groove. Alternatively, the groove width can be reduced without reducing the tensile strength, and such an effect is particularly remarkable in the case of a track shape that is long in one direction.

  The wire for electric discharge machining is particularly suitable for multi-electric discharge machining in which a plurality of portions of a workpiece are simultaneously subjected to electric discharge cutting in a parallel direction. In this case, the electric discharge machining method is such that the electric discharge machining wire is supplied from a supply reel, wound multiple times at equal intervals between the rollers, and wound around the discharge reel. The plurality of wire portions are moved while being parallel to each other between the rollers, and the workpiece is brought close to the plurality of wire portions of the wire for electric discharge machining that are parallel to each other between the rollers from the discharge area side. On the other hand, power feeding is performed from the power feeding area side, electric discharge is generated between the wire portion and the workpiece, and a plurality of portions of the workpiece are simultaneously subjected to electric discharge cutting.

  In this way, by performing multi-electric discharge machining using a wire for electric discharge machining in which the power feeding area is separated from the electric discharge area by the non-electric discharge area, the electric discharge area of the same part of the wire sequentially approaches a plurality of locations on the workpiece. Even if the discharge area is roughened by repeating the discharge several times, the power can be supplied stably. In addition, the discharge can be efficiently generated only in the processing direction, and the yield can be improved by minimizing the portion where the workpiece is melted and removed.

  As is apparent from the above description, according to the present invention, in wire electric discharge machining in which the machining direction is specified as one direction, electric discharge can be efficiently generated only in the machining direction, and the workpiece is melted and removed. Therefore, the yield can be improved and the power can be stably supplied.

It is sectional drawing (a) orthogonal to the wire longitudinal direction of the wire for electrical discharge machining with a circular cross section which concerns on an example of embodiment of this invention, and an external appearance perspective view (b). It is explanatory drawing (a)-(c) of the deformation | transformation aspect of the wire for electrical discharge machining with a circular cross section which concerns on embodiment of FIG. It is sectional drawing (a)-(c) orthogonal to the wire longitudinal direction of the wire for electric discharge machining with a circular cross section which concerns on other embodiment of this invention. It is sectional drawing (a)-(e) orthogonal to the wire longitudinal direction of the wire for electrical discharge machining which concerns on other embodiment of this invention. 1 is a schematic view of a multi-electric discharge machine according to an embodiment of the present invention. It is sectional drawing (a)-(c) orthogonal to the wire longitudinal direction of the conventional typical electric discharge machining wire.

  FIGS. 1A and 1B show an electric discharge machining wire 10 having a circular cross section according to an example of an embodiment of the present invention. This wire for electric discharge machining 10 is a wire having a circular cross-section in which the core material portion is composed only of the base material 11, and on the wire surface, one discharge area A continuous in the wire longitudinal direction at the same peripheral edge of the wire cross-section, Two non-discharge regions B that are continuous in the wire longitudinal direction on both sides in the circumferential direction of the discharge region A, and a power supply region C that is continuous from the discharge region A by the non-discharge region B and that is continuous in the wire longitudinal direction Yes. Then, as shown in FIG. 1A, the discharge area A, the non-discharge area B, and the power supply area C are arranged in line symmetry with respect to the symmetry axis S passing through the discharge area A and the power supply area C in the wire cross section. Yes. The number of non-discharge areas B is preferably two, but may be more.

  The base material 11 is brass, tungsten, molybdenum or the like. Generally, tungsten is used. Tungsten wire has high electrical conductivity and is tough. The base material 11 is exposed on the wire surface in an arrangement facing the cross section of the wire, and a region of the wire surface where the base material 11 is exposed forms a discharge area A and a power feeding area C. The region sandwiched between the discharge region A and the power supply region C has a higher electrical resistance than the base material 11 on the wire surface, and does not conduct electricity at a normal use voltage, specifically, 50V to 300V. A non-discharge region B is formed by being covered with an insulating layer 12 made of a resin such as rubber (which is not particularly limited).

  The insulating layer 12 in the non-discharge region B is, for example, a region where the wire core material made only of the base material 11 is drawn, immersed in a molten resin while being traveled, and further traveled to be the non-discharge region B. It can be formed by peeling off the resin adhering to the region desired to be the discharge region A and the region desired to be the power feeding region C. In this way, the resin adhering to the region desired to be the discharge region A and the region desired to be the power feeding region B is peeled off, and then dried, whereby the insulating layer 12 is formed by the resin that has not been peeled off, and the insulating layer 12 is formed. This area becomes the non-discharge area B. The areas where the resin is peeled off are the discharge area A and the power supply area C.

  This electric discharge machining wire 10 is suitable for unidirectional machining such as slicing machining of compound semiconductors and the like, particularly for multi-electric discharge machining. Since the discharge area A is specified in the circumferential direction on the surface of the wire, high-speed machining is performed. In addition, the generation of useless discharge that does not contribute to unidirectional machining is suppressed, the part where the workpiece is melted and removed is minimized, and the formation of a smooth machined surface is realized. The processing width can be reduced and the yield of the workpiece can be improved.

  In the electric discharge machining wire 10, the power supply area C is separated from the discharge area A by the non-discharge area B on the wire surface, and the discharge area A can be dedicated to discharge and the power supply area C can be dedicated to power supply. Moreover, the discharge area A, the non-discharge area B, and the power supply area C are arranged in line symmetry with respect to the symmetry axis S passing through the discharge area A and the power supply area C in the wire cross section, and the discharge area A and the power supply area C are opposed to each other. Since the power feeding area C is sufficiently separated from the discharge area A, unnecessary discharge from the power feeding area C can be suppressed, and the power feeding surface can be always kept smooth. Even when the discharge area A is rough because the discharge area A of the same portion sequentially approaches a plurality of locations of the workpiece and repeats the discharge several times, stable power feeding can be performed, and the discharge is also stabilized.

If the discharge area A, the non-discharge area B, and the power supply area C are not line-symmetric with respect to the symmetry axis S passing through the discharge area A and the power supply area C in the wire cross section, the discharge area A and the power supply area C are not opposed to each other. , both sides of the non-discharge area B (If it is a non-discharge area B of the both sides of the discharge region a is a non-discharge area B on both sides at the same time sandwiching the feeding zone C) becomes unbalanced, the feed zone C is the wire cross-section In this case, it is shifted from the position facing the discharge area A and is biased to one side, and approaches the discharge area A. Therefore, it becomes difficult to supply power, and further, the electric discharge is discharged from the power supply area. Moreover, there is a possibility that the processing groove width becomes large.

  In the electric discharge machining wire 10 having a circular cross section, the ratio of the electric discharge area A to the circumference of the wire cross section is preferably 120 ° to 250 ° in circumference angle, particularly 120 ° to 170 °. preferable.

  In order to make the machined surface of the workpiece smooth and perform highly accurate machining, electric discharge machining is performed under the condition that the voltage setting of the electric discharge machine is lowered and the electric discharge gap is reduced. A is preferably set to 160 ° to 170 °.

  In order to increase the machining speed, the electric discharge machining is performed under the condition that the voltage setting of the electric discharge machine is increased and the discharge gap is increased. In that case, the discharge area A is preferably narrowed. Even if the discharge area A is narrowed, a sufficient groove width for the wire to advance can be ensured by processing with a large discharge.

  As shown in FIG. 2, the ratio of the discharge area A (circular angle in the wire cross section) can be variously changed depending on the size and arrangement of the non-discharge area B.

  FIGS. 2A to 2C show deformation modes of the electric discharge machining wire having a circular cross section according to the embodiment of FIG. (A) is an electric discharge machining wire 101 in which the non-discharge area B is narrowed, (b) is an electric discharge machining wire 102 in which the non-discharge area B is widened, and (c) is an electric discharge machining in which the discharge area A is wider than the power feeding area C. Each wire 103 is shown.

  When the non-discharge area B is narrowed as in the electric discharge machining wire 101 shown in FIG. 2A, the discharge area A is widened, resulting in a wide-angle discharge. In this case, the processing is performed by a small electric discharge, and the smoothness of the processed surface can be improved.

  If the non-discharge area B is widened like the wire 102 for electric discharge machining shown in FIG. 2B, the discharge area A is narrowed and discharge is performed at a narrow angle. In this case, machining is performed with a large electric discharge, and the machining speed can be increased.

  As in the electric discharge machining wire 103 shown in FIG. 2C, the non-discharge area B is arranged so that the discharge area A is wider than the power supply area C, thereby securing the discharge area so that wide-angle discharge is possible. Therefore, it becomes easy to improve the smoothness of the processed surface as processing by small electric discharge.

  Further, the present invention provides an electric discharge machining wire in which the core material portion is formed by forming a metal layer on the surface of the base material by plating or the like in addition to the electric discharge machining wire whose core material portion is made of only the base material as in the above embodiment. Alternatively, the present invention can also be applied to a wire having a circular cross section in which the core portion forms a metal layer on the surface of the base material and further forms a high resistance layer on the outermost surface. FIGS. 3A to 3C show the structure of an electric discharge machining wire having a circular cross section according to another embodiment of the present invention.

  An electric discharge machining wire 111 shown in FIG. 3A is a wire having a circular cross-section in which the core portion is formed by forming the metal layer 13 on the surface of the base material 11. The electric discharge machining wire 111 is arranged on the wire surface in a line-symmetric arrangement like the electric discharge machining wire 10 according to FIG. 1, and is one discharge area continuous in the longitudinal direction of the wire at the same peripheral portion of the wire cross section. A, two non-discharge regions B continuous in the wire longitudinal direction on both sides in the circumferential direction of the discharge region A, and a power supply region C continuous in the wire longitudinal direction separated from the discharge region A by these non-discharge regions B Have. The number of non-discharge areas B is preferably two, but may be more.

  In the electric discharge machining wire 111, the material of the base material 11 is the same as that in the embodiment according to FIG. The metal layer 13 is formed by plating or modification, and is, for example, a brass plating layer. The metal layer 13 is exposed on the wire surface in an opposing arrangement in the wire cross section, and the region of the wire surface where the metal layer 13 is exposed forms the discharge area A and the power feeding area C. A region sandwiched between the discharge region A and the power supply region C is covered with an insulating layer 12 made of nylon resin or the like having a higher electrical resistance than the metal layer 13 on the wire surface to form a non-discharge region B. . The insulating layer 12 in the non-discharge area B is formed in the same manner as in the embodiment according to FIG.

  In the electric discharge machining wire 112 shown in FIG. 3B, the core material portion has a metal layer 13 formed on the surface of the base material 11, and a high electrical resistance higher than that of the base material 11 on the substantially entire surface. A wire having a circular cross section formed by forming a resistance layer 14. The electric discharge machining wire 112 is arranged on the wire surface so as to be line-symmetric like the electric discharge machining wire 10 according to FIG. 1, and is one electric discharge continuous in the longitudinal direction of the wire at the same peripheral portion of the wire cross section. A region A, two non-discharge regions B continuous in the wire longitudinal direction on both sides in the circumferential direction of the discharge region A, and a power supply region C continuous in the wire longitudinal direction separated from the discharge region A by the non-discharge region B have. The number of non-discharge areas B is preferably two, but may be more.

  In this electric discharge machining wire 112, the material of the base material 11 is the same as that in the embodiment according to FIG. The metal layer 13 is formed by plating or modification, and is, for example, a brass plating layer. The high resistance layer 14 is a non-insulating high resistance layer made of a resin such as an alkyd resin, a polyethylene resin, or a polyester resin, or a metal carbide. The high resistance layer 14 is exposed on the wire surface in an opposing arrangement in the wire cross section, and the region of the wire surface where the high resistance layer 14 is exposed forms a discharge area A and a power supply area C, and the discharge area A and the power supply area A region sandwiched between C is covered with an insulating layer 12 made of nylon resin or the like having a higher electrical resistance than the high resistance layer 14 on the wire surface, and a non-discharge region B is formed. Also in this case, the insulating layer 12 in the non-discharge region B is formed in the same manner as in the embodiment according to FIG.

  An electric discharge machining wire 113 shown in (c) of FIG. 3 is a wire having a circular cross-section in which the core portion forms the metal layer 13 on the surface of the base material 11, and further, the discharge region on the outermost surface A high resistance layer 14 having an electric resistance higher than that of the base material 11 is formed only in the region to be formed, and also on the wire surface, similarly to the electric discharge machining wire 10 according to FIG. One discharge area A (area where the high resistance layer 14 is exposed) in the wire longitudinal direction at the same portion, two non-discharge areas B continuous in the wire longitudinal direction on both sides in the circumferential direction of the discharge area A, and It has the electric power feeding area | region C continued in the longitudinal direction of the wire separated from the discharge area A by the non-discharge area B. Also in this case, the number of non-discharge areas B is preferably two, but may be more.

  In the electric discharge machining wire 113, the material of the base material 11 is the same as that in the embodiment according to FIG. The metal layer 13 is formed by plating or modification, and is, for example, a brass plating layer. The high-resistance layer 14 is a non-insulating high-resistance layer made of a resin such as an alkyd resin, a polyethylene resin, or a polyester resin, or a metal carbide, and forms a discharge area A. The metal layer 13 is exposed to the wire surface in an arrangement facing the high resistance layer 14 in the cross section of the wire to form a power feeding region C, and a region sandwiched between the discharge region A and the power feeding region C is the wire surface. The non-discharge region B is formed by being covered with an insulating layer 12 made of nylon resin or the like having a higher electrical resistance than the high resistance layer 14. The insulating layer 12 in the non-discharge area B is formed in the same manner as in the embodiment according to FIG. The high resistance layer 14 is formed in the same manner after the insulating layer 12 is formed (may be formed prior to the formation of the insulating layer 12).

  As a modification of the electric discharge machining wire 113 shown in FIG. 3C, the high resistance layer 14 may be provided not only in the discharge area A but also in the power supply area C.

  In the example shown in FIGS. 3B and 3C, the high-resistance layer 14 is capable of avoiding concentrated discharge and enhancing dispersive discharge at a voltage in normal use, specifically, a voltage of 50 V to 300 V. Specifically, a metal oxide layer (for example, zinc oxide layer) or a resin layer (for example, a layer made of alkyd resin, polyethylene resin, polyester resin, etc., and formed to a thickness of 0.1 to 5 μm), and others There is no particular limitation as long as it is similar to the above.

  These electric discharge machining wires 111 to 113 are also suitable for unidirectional machining such as slicing machining of compound semiconductors and the like, especially multi-electric discharge machining, and the discharge area A is specified in the circumferential direction on the surface of the wire. High-speed machining can be realized, and unnecessary discharge that does not contribute to unidirectional machining is suppressed, minimizing the part where the workpiece is melted and removed, and forming a smooth machining surface In addition, the processing groove width can be reduced and the yield of the workpiece can be improved. In addition, it is possible to suppress unnecessary discharge from the power supply area C and keep the power supply surface smooth, and even when the discharge surface is rough due to multi-discharge machining or the like, stable power supply can be performed and the discharge is also stable. To do.

  The present invention can also be applied to electric discharge machining wires having various cross-sectional shapes other than circular. 4A to 4E show an embodiment of the present invention applied to an electric discharge machining wire having a cross-sectional shape other than a circular shape.

  The wire for electric discharge machining 121 shown in FIG. 4 (a) is a wire having a quadrangular cross-section in which the core portion is composed only of the base material 11, and is line-symmetrical on the wire surface as in the electric discharge machining wire 10 according to FIG. In this arrangement, one discharge area A continuous in the longitudinal direction of the wire at the same peripheral edge of the wire cross section, two non-discharge areas B continuous in the longitudinal direction of the wire on both sides in the circumferential direction of the discharge area A, A power supply area C that is separated from the discharge area A by the discharge area B and that is continuous in the longitudinal direction of the wire. In the cross section of the wire, the discharge area A and the power supply area C are located in each area centered on a pair of opposite corners of a quadrangle, and the non-discharge area B is located in each area centered on another pair of opposite corners. Is located.

  The electric discharge machining wire 122 shown in FIG. 4 (b) is a hexagonal cross-section wire whose core material portion is composed only of the base material 11, and is also arranged in a line-symmetric manner on the wire surface, and the same peripheral portion of the wire cross-section. 1, one discharge area A continuous in the wire longitudinal direction, two non-discharge areas B continuous in the wire longitudinal direction on both sides in the circumferential direction of the discharge area A, and separated from the discharge area A by these non-discharge areas B And a power feeding region C continuous in the wire longitudinal direction. In the cross section of the wire, the discharge area A and the power supply area C are located on the sides on both sides centered on a pair of opposing corners of the hexagon, and the pair of opposing sides located between the other corners. A non-discharge area B is located.

  An electric discharge machining wire 123 shown in (c) of FIG. 4 is an elliptical wire whose core material portion is composed only of the base material 11 and has a wire cross section that is long in one direction and is also symmetrical with respect to the wire surface. Thus, one discharge region A continuous in the wire longitudinal direction at the same peripheral edge of the wire cross section, two non-discharge regions B continuous in the wire longitudinal direction on both sides in the circumferential direction of the discharge region A, and these non-discharge regions B And a feeding area C continuous in the longitudinal direction of the wire separated from the discharge area A. In the cross section of the wire, the discharge area A and the power feeding area C are located at the opposite peripheral edges of the major axis, and the non-discharge area B is located at the peripheral edge of the minor diameter side.

  An electric discharge machining wire 124 shown in FIG. 4 (d) is a wire having a substantially front-rear circular shape in which the core portion is composed only of the base material 11, and the wire cross section is long in one direction and extends in the longitudinal direction in opposition. It has a pair of straight line portions, and has a curved portion that bulges outward at a rear end portion that is one of the portions that connect opposite ends of both ends of the pair of straight line portions. Then, one discharge area A continuous in the longitudinal direction of the wire at the same peripheral portion of the wire cross-section, and two continuous in the longitudinal direction of the wire on both sides in the circumferential direction of the discharge area A, in a line-symmetrical arrangement on the wire surface. There are two non-discharge areas B and a power supply area C that is separated from the discharge area A by the non-discharge areas B and that is continuous in the longitudinal direction of the wire. In the cross section of the wire, the discharge area A is located on the curved surface portion where the curved part of the rear end portion of the substantially front rear circle is continuous in the wire longitudinal direction, the power feeding area C is located in the front end portion, and the non-discharge area B Is located.

  The wire for electric discharge machining 125 shown in FIG. 4E is a track-shaped wire whose core material portion is composed only of the base material 11. That is, the wire cross-section has a pair of straight portions that are long in one direction and extend in the opposite direction in the longitudinal direction, and bulge outward at the portions connecting the opposite ends of both ends of the pair of straight portions. It has a curved part. Then, one discharge area A continuous in the longitudinal direction of the wire at the same peripheral portion of the wire cross-section, and two continuous in the longitudinal direction of the wire on both sides in the circumferential direction of the discharge area A, in a line-symmetrical arrangement on the wire surface. There are two non-discharge areas B and a power supply area C that is separated from the discharge area A by the non-discharge areas B and that is continuous in the longitudinal direction of the wire. In the cross section of the wire, a discharge area A and a power feeding area C are located at both ends in the longitudinal direction of the track shape, and a non-discharge area B is located at the side face.

  The materials of the base material 11 of these electric discharge machining wires 121 to 125 are the same as those of the embodiment according to FIG. 1, and the base material 11 is exposed on the wire surface in an arrangement facing the cross section of the wire. The area of the wire surface where the material 11 is exposed forms a discharge area A and a power supply area C. A region sandwiched between the discharge region A and the power supply region C is covered with an insulating layer 12 made of nylon resin or the like having a higher electrical resistance than the base material 11 on the wire surface, and a non-discharge region B is formed. . The insulating layer 12 in the non-discharge area B is formed in the same manner as in the embodiment according to FIG.

  These electric discharge machining wires 121 to 125 are also suitable for unidirectional machining, such as slicing machining of compound semiconductors, etc., especially multi-electric discharge machining, and the discharge area A is specified in the circumferential direction on the surface of the wire. High-speed machining can be realized, and unnecessary discharge that does not contribute to unidirectional machining is suppressed, minimizing the part where the workpiece is melted and removed, and forming a smooth machining surface In addition, the processing groove width can be reduced and the yield of the workpiece can be improved. In addition, it is possible to suppress unnecessary discharge from the power supply area C and keep the power supply surface smooth, and even when the discharge surface is rough due to multi-discharge machining or the like, stable power supply can be performed and the discharge is also stable. To do.

  Among these electric discharge machining wires 121 to 125 having a non-circular cross section, the cross sections of the electric discharge machining wires 123, 124, and 125 shown in FIGS. 4C, 4D, and 4E are identical. The wire having the discharge area A and the feeding area C at both ends in the longitudinal direction can increase the tensile strength without increasing the processing groove width, or the processing groove width without decreasing the tensile strength. Is preferable in that it can be reduced. In particular, the electric discharge machining wires 124 and 125 shown in FIGS. 4D and 4E have a pair of straight portions that extend in the longitudinal direction in opposition to each other, and the ends of the pair of straight portions are mutually connected. At least one of the portions that connect the opposing ends has a curved portion that bulges outward, and one of the curved portions in which the curved portion is continuous in the longitudinal direction of the wire is a discharge area A. Therefore, it is advantageous in that the machining groove width can be further reduced and a uniform discharge is easily generated in the machining direction. In particular, the cross-section track-shaped electric discharge machining wire 125 of FIG. 4 (e) can make the machining groove width smaller and easily generate a uniform electric discharge in the machining direction. This is advantageous in terms of wire forming.

  Note that the wire for electric discharge machining other than the circular cross section to which the present invention can be applied is not limited to those shown in FIGS. 4 (a) to 4 (e). The present invention can also be applied to electric discharge machining wires having various other cross-sectional shapes.

  Moreover, although embodiment shown to (a)-(e) of FIG. 4 is an example of the wire for electrical discharge machining whose core material part consists only of the base material 11, this invention is (a)-( The wire for electric discharge machining having the same or other irregular cross-sectional shape as shown in e), wherein the core portion is formed with a metal layer by plating or the like on the surface of the base material, like the wire shown in FIG. As in the wire shown in FIG. 3B and the wire shown in FIG. 3C, the core portion forms a metal layer on the surface of the base material and further forms a high resistance layer on the outermost surface. The present invention can also be applied to an electric discharge machining wire.

  FIG. 5 shows a schematic structure of the multi-electric discharge machine 20 according to the embodiment of the present invention. The multi-electric discharge machine 20 includes a supply reel 21 for supplying a wire W (electric discharge machining wire), a supply-side guide roller 22 for guiding the wire W supplied from the supply reel 21, and a wire on the roller surface. Forms a working fluid atmosphere around a plurality of parallel (four in the illustrated example) main rollers 23 having a groove for wrapping W multiple times at equal intervals, and the wire W traveling between the main rollers 23 And a grooved positioning roller that keeps the wire interval (pitch) constant while preventing the wire W from being shaken by discharging the wire W before and after the working fluid supply device 24 25, an electric feeder 26 for supplying power from the side opposite to the positioning roller 25 (lower side in the illustrated example) with respect to the traveling wire W before and after the machining liquid supply device 24, and the workpiece K is moved up and down, the workpiece K is brought closer (lowered in the illustrated example) from the side opposite to the power supply 26 (upper in the illustrated example), and between the wire W and the workpiece K in the processing liquid atmosphere. A work feeding device 27 that generates electric discharge, a discharge-side guide roller 28 that guides a used wire W that has traveled between the main rollers 23 a plurality of times, and a discharge reel 29 that winds up the used wire W that has been guided. It has.

  Using this multi-electric discharge machine 20, the wire W is supplied from the supply reel 21, guided by the guide roller 22, wrapped around the main roller 23 in multiples at equal intervals, and in the working liquid atmosphere between the main rollers 23. In the state where tension is applied by the positioning roller 25, the wire W is caused to run in a state where the plurality of wire portions are parallel to each other between the main rollers 23 while power is supplied by the power supply 26. While feeding the workpiece from the discharge area A side to the plurality of wire portions traveling in parallel with each other, power is supplied to the plurality of wire portions from the power supply region C side via the feeders 26, and the wire portions By generating an electric discharge between the workpiece K and the workpiece K, a plurality of locations on the workpiece K are simultaneously subjected to electric discharge cutting (slicing). Then, the used wire W is guided by the guide roller 28 and wound around the discharge reel 29 to slice the compound semiconductor or the like.

  And in this multi-electric discharge machine 20, as a wire W (wire for electric discharge machining), the electric discharge machining wires (10, 101 to 103, 111 to 11) of the embodiment shown in FIG. 1, FIG. 2, FIG. 3 and FIG. 113, 121-125), etc., using the wire for electric discharge machining according to the present invention, the electric discharge area A faces the workpiece K at the machining position, and the power feeding area C faces the electric supply 26 at the machining position. Set to run in a posture to do.

  By performing multi-electric discharge machining in this way, power feeding can be performed stably, and since the portion to be discharged on the surface of the wire is specified in the circumferential direction, wire discharge that specifies the machining direction in one direction In machining, electric discharge can be efficiently generated only in the machining direction, and the portion where the workpiece is melted and removed can be minimized to improve the yield.

DESCRIPTION OF SYMBOLS 10 Wire for electric discharge machining 11 Base material 12 Insulating layer 13 Metal layer 14 High resistance layer 20 Multi electric discharge machine 21 Supply reel 22 Guide roller 23 Main roller 24 Processing liquid supply device 25 Positioning roller 26 Electric supply 27 Work feeding device 28 Guide roller 29 Ejection reels 101, 102, 103 Electric discharge machining wires 111, 112, 113 Electric discharge machining wires 121, 122, 123, 124, 125 Electric discharge machining wires A Discharge area B Non-discharge area C Power supply area S Symmetric axis W Wire ( EDM wire)

Claims (5)

On the surface of the wire, one discharge region continuous in the wire longitudinal direction at the same peripheral edge of the wire cross section, at least two non-discharge regions continuous in the wire longitudinal direction on both sides in the circumferential direction of the discharge region, and the non-discharge region A wire for electric discharge machining having a power supply region continuous in the longitudinal direction of the wire separated from the electric discharge region ,
The core part is formed by forming a metal layer on the surface of the base material, and further forming a high resistance layer having a higher electrical resistance than the base material on the outermost surface,
The high resistance layer is exposed on the wire surface in an opposing arrangement in the cross section of the wire, and the area of the wire surface where the high resistance layer is exposed forms the discharge area and the power supply area. An electric discharge machining wire characterized in that the sandwiched region is covered with an insulating layer having an electric resistance higher than that of the high-resistance layer on the wire surface to form the non-discharge region . 2. The electric discharge machining according to claim 1, wherein the discharge area, the non-discharge area, and the power supply area are arranged in line symmetry with respect to an axis of symmetry passing through the discharge area and the power supply area in a wire cross section. Wire. The cross section of the wire has a pair of straight portions that are long in one direction and extend in the opposite direction in the longitudinal direction, and outward to at least one of the portions that connect the opposite ends of both ends of the pair of straight portions. The electric discharge machining according to claim 1 or 2, wherein the electric discharge machining is a wire having a swollen curved portion, wherein the electric discharge area is provided in one of the curved portions in which the curved portion is continuous in the longitudinal direction of the wire. For wire. The shape of the wire cross-section is a track shape in which the pair of straight portions are the same size and parallel to each other, and the curved portions are provided at both ends of the pair of straight portions that connect the opposite ends. The wire for electric discharge machining according to claim 3. On the surface of the wire, one discharge region continuous in the wire longitudinal direction at the same peripheral edge of the wire cross section, at least two non-discharge regions continuous in the wire longitudinal direction on both sides in the circumferential direction of the discharge region, and the non-discharge region An electric discharge machining wire having a power supply area continuous in the longitudinal direction of the wire separated from the discharge area is supplied from the supply reel, and is wound around the discharge reel by multiple winding at equal intervals between the rollers. A machining wire is run with a plurality of wire portions parallel to each other between the rollers, and a plurality of wire portions of the electrical discharge machining wire that run in parallel with each other between the rollers are moved from the discharge zone side. While feeding the workpieces, power is supplied to the plurality of wire portions from the feeding region side, and an electric discharge is generated between the wire portions and the workpieces. Multi discharge machining method characterized by simultaneously discharging cutting a plurality of locations in factory product.

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