JP2012245567A - Wire for electric discharge machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform highly accurate machining without causing no exfoliation when wire tension is increased, in a wire for electric discharge machining for the purpose of machining in a specific direction such as one direction.SOLUTION: The wire 10 for electric discharge machining has a discharge region A and a non-discharge region B that are continuous in the wire longitudinal direction on the wire surface. The non-discharge region is formed of an insulation layer 12 which has a thickness of 0.1-6 μm and a Shore D hardness of 60-90 and is obtained by mixing or by being mixed with the chemical bonding of a hard segment and a soft segment where the hard segment is composed of thermosetting resins such as a phenol resin, an epoxy resin, and a polyimide resin, and the soft segment is composed of elastomers that are homogeneous or heterogeneous with thermosetting resins such as a polyvinylbutyral resin, an epoxy resin, a polyimide resin, a polyamide resin, and SEBS.

Description

  The present invention relates to an electric discharge machining wire for wire electric discharge machining that cuts a workpiece by electric discharge energy, and more particularly to an electric discharge machining wire suitable for one-way machining such as electric discharge slicing or other specific machining.

  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 μm to several tens of μm, 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 is composed of a series of steps of melting, explosion, scattering, cooling, and sludge removal. 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 mm 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 electrical discharge machining has been considered for use in slicing (discharge slicing) of hard and brittle materials such as Si and SiC compound semiconductors as well as machining complex shapes due to improved machining performance. Has been.

  And as a method of such electric discharge slicing, the electric discharge machining wire is supplied from the supply reel, is wound around the discharge reel by multiple winding at equal intervals between the rollers, and runs in a state parallel to each other between the rollers of the wire. A plurality of portions of the workpiece are simultaneously cut by applying a voltage from the power supply region side via the power supply to generate a discharge while bringing the workpiece from the discharge region side closer to the plurality of wire portions to be So-called multi-discharge machining (see, for example, Patent Documents 3 and 4) has been conventionally known.

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 as one direction, such as electric discharge slicing. There is a difference in required machining performance between electric discharge machining for forming a complicated machining surface and simple slit machining such as electric discharge slicing.

  The fact that the wire surface has a uniform machining performance over the entire surface like a conventional wire for electric discharge machining is inconvenient for machining in a specific direction such as electric discharge slicing, and is unnecessary in other than the machining direction. Generated, 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, the machining groove width increases. Yield reduction due to is increased.

  In electric discharge machining to form a complex machined surface, the direction of cutting by electric discharge (hereinafter referred to as the machining direction) changes every moment in order to obtain a complex machined surface. The circumferential position of the wire surface facing the 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 machining in a specific direction such as one direction such as electric discharge slicing, the fact that the wire surface has a uniform machining performance over the entire surface like a conventional electric wire for electric discharge machining is rather harmful. .

  In the case of machining in a specific direction such as one direction, it is sufficient that electric discharge is performed only in a specific machining direction. However, when a conventional electric discharge machining wire is used, not only the machining direction but also the width in the machining direction. Discharge occurs in a wide range from both sides in the direction to the rear. Such a discharge other than the machining direction is not only a useless discharge that does not directly contribute to the machining but is also harmful, and the unwanted discharge 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 described above, the wire for electric discharge machining used for machining in a specific direction such as one direction can efficiently generate electric discharge that contributes to machining in a specific direction to realize high-speed machining, and also in a specific direction. It is required that the generation of useless discharge that does not contribute to the machining of the workpiece can be suppressed, a smooth machining surface can be formed, and the machining groove width can be reduced to improve the yield of the workpiece. .

  Therefore, as an electric discharge machining wire having machining performance required for machining in a specific direction such as one direction, a non-discharge area is formed on a part of the wire surface to limit the discharge area to a specific direction. A wire for electric discharge machining configured to obtain machining performance required for machining in a specific direction such as a direction, for example, a discharge area continuous in the longitudinal direction of the wire at the same peripheral edge of the wire cross section on the wire surface, and the discharge area A wire for electric discharge machining having a non-discharge region continuous in the longitudinal direction of the wire is considered. The non-discharge region can be formed by coating with resin or the like.

  By configuring the wire for electric discharge machining in this way, the portion to be discharged on the surface of the wire is specified in the circumferential direction, so that electric discharge can be efficiently generated only in the machining direction, and the workpiece is melted and melted. It is possible to improve the yield by minimizing the portion to be removed.

  By the way, in order to increase the machining accuracy of the wire electric discharge machining, it is necessary to increase the wire tension so that the traveling wire does not move left and right during the machining. However, a part of the wire surface is coated with a resin to form a non-discharge region, and the discharge region is limited to the circumferential direction so that the processing performance required for processing in a specific direction such as one direction can be obtained. In the case of an electric discharge machining wire, if the wire tension is increased from about 10 N to about 20 to 30 N, for example, the resin easily peels off.

  As a resin to be coated to form a non-discharge region, first, a general resin such as a polystyrene resin or a polyester resin can be considered. Since these polystyrene resins and polyester resins are not so high in hardness, the wire tension is set to, for example, When the pressure is increased to about 20 to 30 N, the resin is peeled off by rubbing with a roller or the like in the processing equipment, and the peeled material may be accumulated on the roller or the processing portion to adversely affect the processing.

  Therefore, it is conceivable to use a resin having higher hardness, for example, a thermosetting resin such as a phenol resin, a polyimide resin, or an epoxy resin. However, since these high-hardness thermosetting resins are low in flexibility and weak in bending, when the wire tension is increased to, for example, about 20 to 30 N, surface cracking occurs when the wire is bent by a roller or the like in a processing facility. Occurrence occurs and peeling occurs, and the peeled material may accumulate on the roller and the processing portion, which may adversely affect the processing.

  Therefore, it is possible to efficiently generate discharge only in the processing direction in processing in a specific direction such as one direction, to minimize the part where the workpiece is melted and removed, and to perform processing with high yield, And it is a subject to provide the wire for electrical discharge machining which can implement | achieve highly accurate process, without a peeling thing producing even if wire tension is increased.

  As a result of extensive research, the present invention has found that the above-mentioned problems can be solved by using a resin in which a material having high hardness and a material having relatively high flexibility are mixed or mixed by chemical bonding. It is embodied as an electric discharge machining wire.

  That is, the wire for electric discharge machining of the present invention has a discharge area on the wire surface having a discharge area continuous in the wire longitudinal direction at the same peripheral edge of the wire cross section and a non-discharge area continuous in the wire longitudinal direction along the discharge area. A wire for processing, in which the non-discharge region is a mixture of a relatively hard material (hard segment) and a relatively low hardness material (soft segment) mixed or chemically bonded It is formed by an insulating layer formed by coating a resin.

  This wire for electric discharge machining uses, for example, a thermosetting resin such as a phenol resin, an epoxy resin, or a polyimide resin as a relatively hard material (hard segment), and has a relatively low hardness and high flexibility. As the (soft segment), for example, the same type or different type of elastomer as the thermosetting resin such as polyvinyl butyral resin, epoxy resin, polyimide resin, polyamide resin, SEBS (styrene = ethylene = butylene = styrene) is used. Good. The resin of the insulating layer in which they are mixed preferably has a Shore D hardness (durometer D hardness defined in JIS K 7215) of 60 to 90.

  This wire for electric discharge machining has, on the wire surface, a discharge area that is continuous in the wire longitudinal direction at the same peripheral edge of the wire cross section, and a non-discharge area that is continuous in the wire longitudinal direction along the discharge area, A portion that discharges on the surface of the wire is specified in the circumferential direction. Therefore, in one-way machining such as electric discharge slicing and other wire electric discharge machining in a specific direction, electric discharge can be generated efficiently only in the machining direction, minimizing the part where the workpiece is melted and removed, Yield can be improved.

  In this electric discharge machining wire, the non-discharge region is a mixture of a relatively hard material (hard segment) and a relatively low hardness and high flexibility material (soft segment) by mixing or chemical bonding. By being formed of an insulating layer coated with a matching resin, the resin hardness of the insulating layer can be increased moderately, and it has appropriate flexibility, excellent flexibility, and adhesion. Can be good. Therefore, even if the wire tension is increased more than usual, it is possible to make it difficult for the resin to be peeled off by rubbing with a roller or the like in the processing equipment, or to be peeled off by bending with a roller or the like. Can be increased more than usual, and wire deflection during processing can be suppressed, and more accurate processing can be realized.

  Thus, according to the wire for electric discharge machining of the present invention, in one-way machining such as electric discharge slicing or other specific direction machining, an electric discharge is efficiently generated only in the machining direction, and the workpiece is melted and removed. It is possible to perform processing with a high yield while minimizing the portion, and even if the wire tension is increased, no delamination occurs and high-accuracy processing can be realized.

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, There are two non-discharge regions B that are continuous in the longitudinal direction of the wire along the discharge region A on both sides in the circumferential direction of the discharge region A. And the electric power feeding area | region C which continues in the wire longitudinal direction by the arrangement | positioning separated from the discharge area A by the two non-discharge areas B is formed. In this example, the discharge area A, the non-discharge area B, and the power supply area C are 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, as shown in FIG. It is an arrangement. The number of non-discharge areas B is preferably two, but may be larger.

  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. A region sandwiched between the discharge region A and the power supply region C is made of a resin having an insulating property that has higher electrical resistance than the base material 11 on the wire surface and does not conduct electricity at a voltage (50 V to 300 V) in normal use. It is covered with an insulating layer 12 having a thickness of 0.1 to 6 μm (not limited to this) and a Shore D hardness of 60 to 90, thereby forming a non-discharge region B.

  The insulating layer 12 includes a hard segment (material having relatively high hardness) made of thermosetting resin such as phenol resin, epoxy resin, polyimide resin, etc., polyvinyl butyral resin, epoxy resin, polyimide resin, polyamide resin, SEBS, etc. The soft segment (a material having relatively low hardness and high flexibility) made of the same type or different type of elastomer as the thermosetting resin is formed of a resin mixed by mixing or chemical bonding.

  For example, the insulating layer 12 of the resin is obtained by drawing a wire core made of only the base material 11 and then dipping it in a molten resin in which the hard segment and the soft segment are mixed and running while running. 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 other than the region desired to be the non-discharge region B. 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 one-way machining such as electric discharge slicing (slicing machining of compound semiconductors) and other specific machining, and particularly suitable for multi-electric discharge machining. Because it is specified in the direction, it is possible to efficiently generate discharge only in the machining direction, to achieve high-speed machining, and to suppress the generation of unnecessary discharge that does not contribute to machining in a specific direction, It is possible to minimize the portion where the workpiece is melted / removed, to form a smooth processed surface, and to reduce the width of the processed groove to improve the yield of the workpiece.

  The resin insulation layer 12 forming the non-discharge region B is a mixture of hard segments and soft segments, having appropriate hardness and flexibility, good adhesion, and a wire for discharge slicing. Excellent flexibility, abrasion resistance, peel resistance, and heat resistance required for the resin to be coated. Especially, peeling due to rubbing with a roller or the like in a processing facility or peeling due to bending with a roller or the like hardly occurs. Yes. And it becomes possible to increase wire tension to about 20-30N so that a highly accurate process may be implement | achieved.

  In addition, the electric discharge machining wire 10 has a power feeding area C separated from a discharge area A by a non-discharge area B on the wire surface, and the discharge area A can be dedicated to discharging and the feeding area C can be dedicated to feeding. 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.

  In the discharge area A, the ratio of the wire cross section to the circumference is preferably 120 ° to 250 ° in circumference angle, and particularly preferably 120 ° to 170 °. In addition, in order to smooth the work surface of the workpiece and achieve high-precision machining, the electric discharge machining is performed under the condition that the voltage setting of the electric discharge machine is lowered and the discharge gap is reduced. The discharge area 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.

  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. Moreover, when 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. Further, by disposing the non-discharge area B so that the discharge area A is wider than the power supply area C as in the electric discharge machining wire 103 shown in FIG. It is possible to ensure 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 larger.

  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. The region sandwiched between the discharge region A and the power supply region C is made of a resin having an electrical resistance higher than that of the metal layer 13 on the wire surface and not conducting electricity at a voltage (50 V to 300 V) in normal use. The non-discharge area B is formed by being covered with an insulating layer 12 having a thickness of 0.1 to 6 μm (not limited to this). 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 larger.

  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 such as a metal oxide layer (for example, zinc oxide layer) or 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 The region sandwiched between C has a thickness of 0.1 to 6 μm made of an insulating resin that has higher electrical resistance than the high resistance layer 14 on the wire surface and does not conduct electricity at a normal use voltage (50 V to 300 V). 0.1 to 6 μm is preferable, but not limited thereto.), And the 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.

  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. In this case as well, the number of non-discharge areas B is preferably two, but may be larger.

  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 thickness is 0.1 to 6 μm (preferably 0.1 to 6 μm, which is made of an insulating resin that has higher electrical resistance than the high resistance layer 14 and does not conduct electricity at a voltage (50 V to 300 V) in normal use. In other words, the non-discharge area 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. The high resistance layer 14 is formed in the same manner as the insulating layer 12 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 examples shown in FIGS. 3B and 3C (including modifications), the high-resistance layer 14 avoids concentrated discharge at a voltage in normal use, specifically, a voltage of 50 V to 300 V, and distributes it. This is to increase the discharge performance.

  These electric discharge machining wires 111 to 113 are also suitable for one-way machining such as electric discharge slicing (slicing machining of compound semiconductors) or other specific machining, and particularly suitable for multi-electric discharge machining. Since the surface is specified in the circumferential direction, discharge can be efficiently generated only in the machining direction, high-speed machining can be realized, and generation of useless discharge that does not contribute to machining in a specific direction As a result, the portion where the workpiece is melted and removed can be minimized to form a smooth machining surface, and the machining groove width can be reduced to improve the yield of the workpiece.

  The resin insulation layer 12 forming the non-discharge region B is a mixture of hard segments and soft segments, having appropriate hardness and flexibility, good adhesion, and a wire for discharge slicing. Excellent flexibility, wear resistance, peel resistance, and heat resistance required for the resin to be coated. Especially, peeling due to rubbing with a roller or the like in a processing facility or peeling due to bending with a roller or the like hardly occurs. Yes. Therefore, it is possible to increase the wire tension to about 20 to 30 N so as to realize highly accurate processing.

  In addition, these electric discharge machining wires 111 to 113 have a power feeding area C separated from a discharge area A by a non-discharge area B on the wire surface, the discharge area A being dedicated to discharging, and the feeding area C being dedicated to feeding. In addition, 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 passing through the discharge area A and the power supply area C in the wire cross section. Oppositely, since the power feeding area C is sufficiently separated from the discharge area A, useless discharge from the power feeding area C can be suppressed, and the power feeding surface can always be kept smooth. Even when the discharge area is rough because the discharge area A of the same portion of the wire sequentially approaches a plurality of locations of the workpiece and repeats the discharge several times, stable power feeding can be performed, and thus the discharge is also stabilized.

  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 portion 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 on the front end portion, and the non-discharge area B on the side surface portion. 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 both straight portions.

  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 made of a resin having an insulating property that has higher electrical resistance than the base material 11 on the wire surface and does not conduct electricity at a voltage (50 V to 300 V) in normal use. A non-discharge region B is formed by being covered with an insulating layer 12 having a thickness of 0.1 to 6 μm (not limited to this) and a Shore D hardness of 60 to 90. 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 one-way machining such as electric discharge slicing (slicing machining of compound semiconductors, etc.) and other specific machining, particularly suitable for multi-electric discharge machining. Since the surface is specified in the circumferential direction, discharge can be efficiently generated only in the machining direction, high-speed machining can be realized, and generation of useless discharge that does not contribute to machining in a specific direction As a result, the portion where the workpiece is melted and removed can be minimized to form a smooth machining surface, and the machining groove width can be reduced to improve the yield of the workpiece.

  The resin insulation layer 12 forming the non-discharge region B is a mixture of hard segments and soft segments, having appropriate hardness and flexibility, good adhesion, and a wire for discharge slicing. Excellent flexibility, wear resistance, peel resistance, and heat resistance required for the resin to be coated. Especially, peeling due to rubbing with a roller or the like in a processing facility or peeling due to bending with a roller or the like hardly occurs. Yes. Therefore, it is possible to increase the wire tension to about 20 to 30 N so as to realize highly accurate processing.

  In addition, these electric discharge machining wires 121 to 125 have a power supply area C separated from a discharge area A by a non-discharge area B on the wire surface. The discharge area A is dedicated to discharge and the power supply area C is dedicated to power supply. In addition, 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 passing through the discharge area A and the power supply area C in the wire cross section. Oppositely, since the power feeding area C is sufficiently separated from the discharge area A, useless discharge from the power feeding area C can be suppressed, and the power feeding surface can always be kept smooth. Even when the discharge area is rough because the discharge area A of the same portion of the wire sequentially approaches a plurality of locations of the workpiece and repeats the discharge several times, stable power feeding can be performed, and thus the discharge is also stabilized.

  Among these electric discharge machining wires 121 to 125 having a non-circular wire cross section, the electric wire cross sections such as the electric discharge machining wires 123, 124, and 125 in FIGS. 4C, 4D, and 4E are unidirectional. A long wire having a discharge area A and a feeding area C at both ends in the longitudinal direction can increase the tensile strength without increasing the processing groove width, or reduce the processing groove width without decreasing the tensile strength. It is preferable in that it can be performed. 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. The wire W is fed in a state where a plurality of wire portions are parallel to each other between the main rollers 23 while power is supplied by the power supply 26 in a state where tension is applied by the positioning roller 25. Then, while feeding the workpiece from the discharge area A side to the plurality of wire portions running in parallel with each other between the main rollers 23, the plurality of wire portions are supplied with power from the power supply region C side via the power supply 26. By performing discharge between the wire portions and the workpiece K, a plurality of portions of the workpiece K are simultaneously subjected to electric discharge cutting (slicing). The used wire W is guided by the guide roller 28 and wound around the discharge reel 29. By such a method, slicing (discharge slicing) of a compound semiconductor or the like is performed.

  At that time, as the wire W (wire for electric discharge machining), the wire for electric discharge machining (10, 101 to 103, 111 to 113, 121 to 125) of the embodiment shown in FIG. 1, FIG. 2, FIG. 3, FIG. The wire for electric discharge machining of the present invention is used. Then, the wire W is set in the multi-electric discharge machine 20 so that it travels in such a posture that the discharge area A faces the workpiece K and the feeding area C faces the power supply 26 at the machining position.

  As mentioned above, although each embodiment of the present invention was described, the present invention is not limited to these. For example, the present invention is applied to an electric discharge machining wire having a discharge area and a non-discharge area on the wire surface as described above, and having a power supply area in an arrangement separated from the discharge area by the non-discharge area. Further, the present invention can be applied to an electric discharge machining wire in which the wire surface is composed of a discharge region and a non-discharge region, and power is supplied in the discharge region. And when applying to the wire for electric discharge machining in which the wire surface is composed of the discharge region and the non-discharge region, the non-discharge region is one and occupies the whole area of the wire surface excluding the discharge region. There may be two or more. Also, when applied to a wire for electric discharge machining that has a power supply area in an arrangement separated from the discharge area by a non-discharge area on the wire surface, the discharge area, the non-discharge area, and the power supply area are not necessarily symmetrically arranged. Also good. In addition, various embodiments of the present invention are possible within the scope of the technical idea of the invention described in the claims.

  The metal core wire having a cross-sectional track shape shown in FIG. 4 (e), that is, the core portion is made only of a base metal (for example, tungsten), and both end portions of the track shape in the longitudinal direction in the wire cross section are defined as a discharge area and a power supply area. The present invention is applied to a wire for electric discharge machining (metal core wire) in which both straight portions are non-discharge areas, a resol type phenol resin (TD-447 manufactured by Dic) is used as a hard segment, and a polyvinyl butyral resin is used as a soft segment. (Using DENKA # 3000-1 (average polymerization degree 600), a hard segment is formed by coating a resin composed of these hard segments and soft segments on both side straight portions with a thickness of 6 μm as non-discharge regions. Prepare multiple mixing ratios (weight percent) from 10 to 100 Flexibility, abrasion resistance, peel resistance, were evaluated hardness. The results are as shown in Table 1.

  Flexibility was evaluated by observing the wire after the wire was wound around a roller having a diameter of 50 mm.

  Peeling resistance is evaluated by wrapping a wire around a roller with a diameter of 50 mm, applying a load of 30 N, observing the surface of the wire after running the wire, x indicating no peeling, and ◯ indicating no peeling. did.

  Similar to the evaluation of peelability, the abrasion resistance is obtained by winding a wire around a roller having a diameter of 50 mm, applying a load of 30 N, and observing the surface of the wire after running the wire, and the resin has a thickness of 0 to 1 μm. Evaluation was made with “X” indicating no remaining, “Δ” indicating 1-3 μm remaining, and “◯” indicating remaining 3 μm or more. For the measurement, a contact-type measuring device was used (measurement using a laser microscope or the like seems to be effective).

  In this case, as shown in Table 1, when the Shore D hardness of the resin of the insulating layer composed of the hard segment and the soft segment is 60 to 90, the evaluation of the flexibility, the wear resistance, and the peel resistance are all good. Therefore, it has the flexibility, wear resistance, and peel resistance necessary for realizing high-precision machining.

  Table 2 also shows the case where the resin of the insulating layer forming the non-discharge region is a polystyrene resin or a polyester resin (conventional example) in the track-shaped metal core wire shown in FIG. In the case of a phenol resin or an epoxy resin (comparative example), the results of evaluation of flexibility, wear resistance, peel resistance, and hardness in the same manner as in Table 1 are shown.

  As shown in Table 2, with a wire having an insulating layer of polystyrene resin or polyester resin (conventional example), the wear resistance evaluation was Δ at a load of 30 N, and the peelability evaluation was x. In addition, in the case of a wire having an insulating layer of polyamide resin, phenol resin or epoxy resin (comparative example), in the case of polyamide resin, only the flexibility is ○, and in the case of phenol resin and epoxy resin, only the wear resistance is ○. It was.

  Also in the metal core wire having a cross-sectional track shape shown in FIG. 4E, a hard segment made of polyimide resin as a hard segment, Rika Coat GN-20 polyimide resin manufactured by Shin Nippon Rika Co., Ltd. is also a polyimide resin as a soft segment. Is a soft type, Rika Coat FN-40 polyimide resin manufactured by Shin Nippon Rika Co., Ltd. A plurality of hard segment mixing ratios (weight percents) were prepared from 10 to 100, and the flexibility, wear resistance, peel resistance, and hardness were evaluated in the same manner as in Table 1. The results are as shown in Table 3.

  Also in this case, as shown in Table 3, when the Shore D hardness of the resin of the insulating layer composed of the hard segment and the soft segment is 60 to 90, the evaluation of the flexibility, the wear resistance, and the peel resistance are all. ○ with the flexibility, wear resistance, and peel resistance necessary for high precision machining.

DESCRIPTION OF SYMBOLS 10 Electric discharge machining wire 11 Base material 12 Insulating layer 13 Metal layer 14 High resistance layers 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

Claims (4)

An electric discharge machining wire having a discharge area continuous in the wire longitudinal direction at the same peripheral edge of the wire cross section on the wire surface, and a non-discharge area continuous in the wire longitudinal direction along the discharge area,
The non-discharge region is formed by an insulating layer formed by coating a resin in which a relatively hard material and a relatively low hardness and high flexibility material are mixed or mixed by chemical bonding. A wire for electric discharge machining characterized by The relatively hard material is a thermosetting resin, and the relatively low hardness and high flexibility material is an elastomer of the same type or different type from the thermosetting resin. Wire for electric discharge machining. The wire for electric discharge machining according to claim 2, wherein the thermosetting resin is a phenol resin, an epoxy resin, or a polyimide resin, and the elastomer is a polyvinyl butyral resin, an epoxy resin, a polyimide resin, a polyamide resin, or SEBS. The wire for electric discharge machining according to claim 1, 2 or 3, wherein the resin of the insulating layer has a Shore D hardness of 60 to 90.

Images