JP2007307669A - Wire electric discharge machine and wire electric discharge machining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means hardly generating unevenness in electric discharge. <P>SOLUTION: This wire electric discharge machine 10 is constituted of a work bench 12 for holding a workpiece W, a wire 20 for machining the workpiece W, traveling parts 22 and 24 for traveling the wire 20 in relation to the workpiece W, and a voltage impressing part 38 for impressing voltage between the wire 20 and the workpiece W to generate electric discharge. A plated layer 60 is formed on an outer peripheral surface 52 of the wire 20. Conductive abrasive grains 54 formed with coating layers 58 are electro-deposited on abrasive grains 56. The conductive abrasive grains 54 are covered with a plated layer 58, and thereby thickness of the plated layer 60 is made thin to shorten time required for electro-deposition. The conductive abrasive grains 54 are coated with the plated layer 60, thereby hardly generating unevenness in spark 62 by electric discharge. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wire electric discharge machine and a wire electric discharge machining method.

A wire electric discharge machine applies a high voltage between a wire and a workpiece while causing the wire to travel with respect to the workpiece, thereby generating an electric discharge between the wire and the workpiece. Process the workpiece. In such a wire electric discharge machine, in order to machine a workpiece also mechanically, abrasive grains such as diamond are fixed to the wire by electrodeposition (see Patent Documents 1 to 4).
JP-A-57-96729 JP 54-14085 A Japanese Patent Laid-Open No. 54-20485 Japanese Patent Laid-Open No. 60-16368

  However, in the wire electric discharge machine in which abrasive grains are electrodeposited on the wire as described above, there is a disadvantage that the processing speed is likely to be lowered because unevenness of spark due to electric discharge is likely to occur.

  In view of such a situation, the present invention is to provide means for making it difficult to cause uneven discharge.

  The present invention applies a voltage between the holding means for holding the workpiece, the wire for processing the workpiece, the traveling means for running the wire relative to the workpiece, and the wire and the workpiece. The wire is a wire electric discharge machine in which conductive abrasive grains are electrodeposited on the surface thereof.

  According to this configuration, since the conductive abrasive grains are electrodeposited on the surface of the wire, in addition to the electrodeposited abrasive grains themselves having conductivity, the surface of the electrodeposited abrasive grains Most of it will be coated with a conductive plating layer. Therefore, unevenness in spark due to discharge is less likely to occur.

  In this specification, the term “conductive abrasive” means that the abrasive itself is conductive, such as abrasive grains made of diamond semiconductor or the like, and abrasive grains coated with a metal film. Includes both conductive and conductive coatings.

  The present invention also applies a voltage between the holding means for holding the workpiece, a wire for processing the workpiece, a traveling means for running the wire relative to the workpiece, and the wire and the workpiece. And a voltage applying means for generating electric discharge, and the wire is a wire electric discharge machine in which abrasive grains coated with a conductive material are electrodeposited on the surface thereof.

  According to this configuration, since the wire is electrodeposited with abrasive grains coated with a conductive material on the surface thereof, the electrodeposited abrasive grains themselves are electrically conductive, and the surface of the abrasive grains is electrically conductive. It is covered with a sex plating layer. Therefore, unevenness in spark due to discharge is less likely to occur. Moreover, since the surface of the abrasive grains is coated with a conductive material, the electrodeposition strength of the abrasive grains can be further increased.

  Further, according to another aspect of the present invention, a voltage is applied between the wire and the workpiece while the wire having the conductive electrode deposited on the surface is run against the workpiece. Thus, a wire electric discharge machining method for machining a workpiece by generating electric discharge is provided.

  According to the wire electric discharge machine and the wire electric discharge machining method according to the present invention, unevenness in electric discharge can be made difficult to occur.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a diagram showing a configuration of a wire electric discharge machine according to an embodiment of the present invention. As shown in FIG. 1, the wire electric discharge machine 10 of the present embodiment includes a work table 12 (holding means) that holds a workpiece W, a wire 20 that processes the workpiece W, and the wire 20 as the workpiece W. Traveling portions 22 and 24 (traveling means) for traveling, voltage applying unit 38 (voltage applying means) for generating a discharge by applying a voltage between the wire 20 and the workpiece W, machining the workpiece W The processing liquid supply unit 42 supplies the processing liquid to the site, and the control unit 48 controls the entire apparatus.

  The work table 12 includes work table drives 14 and 16 and moves the work table 12 holding the workpiece W in the X-axis direction and the Y-axis direction. The work table drivers 14 and 16 are each connected to a work table drive unit 18 and controlled by the work table drive unit 18. Thus, a desired portion of the workpiece W can be machined by freely changing the portion where the workpiece W held on the work table 12 and the wire 20 are in contact with each other.

  Reel portions 26 and 28 for winding the wire 20 are respectively attached to the traveling portions 22 and 24 provided on the wire supply side (upper side in the figure) and the wire recovery side (lower side in the figure), respectively. The wire 20 is guided by guide pulleys 30, 32, 34, and 36. The guide pulleys 30, 32, 34, and 36 can be rotated according to the traveling direction of the wire 20. For this reason, the guide pulleys 30, 32, 34, and 36 are designed to be less worn even when the wire 20 on which the abrasive grains are electrodeposited is guided.

  A voltage application electrode 40 connected to the voltage application unit 38 is provided in contact with the wire 20. The voltage application unit 38 is also electrically connected to the work table 12. As a result, a voltage can be applied between the wire 20 and the workpiece W held on the work table 12 to cause discharge.

  The machining liquid supply nozzles 44 and 46 connected to the machining liquid supply unit 42 are arranged so as to surround the wire 20, and can supply the machining liquid to the machining site of the workpiece W.

  The worktable drive unit 18, the traveling units 22 and 24, the voltage application unit 38, and the machining fluid supply unit 42 described above are each connected to the control unit 48 and controlled to perform a predetermined operation.

  FIG. 2 is a perspective view showing a part of the wire according to the present embodiment. As shown in FIG. 2, the wire 20 according to the present embodiment is configured by electrodepositing conductive abrasive grains 54 on an outer peripheral surface 52 of a core wire 50 that is a linear body made of a piano wire, a stranded wire, or the like. Yes. The thickness of the core wire can be, for example, less than 1 mm.

  FIG. 3 is an enlarged view of the vicinity of the outer peripheral surface of the cross section of the wire according to the present embodiment. As shown in FIG. 3, a conductive layer 54 in which a plating layer 60 of Ni or the like is formed on the outer peripheral surface 52 of the wire 20 and a coating layer 58 is formed on an abrasive grain 56 made of diamond, CNB or the like is plated. Electrodeposited to be embedded in the layer 60. When the conductive abrasive grains 54 are electrodeposited, the plating layer 60 is covered with the conductive abrasive grains 54 as shown in FIG. 3, so that the electrodeposition strength can be increased. Therefore, the thickness of the plating layer 60 can be reduced, and the time required for electrodeposition can be shortened. A coating layer 58 made of any one selected from Ti, Ni, Cu, TiC, and SiC is formed on the surface of the abrasive grains 56 in order to improve the efficiency during electrodeposition. More preferably, the coating layer 58 made of TiC is suitable because the resistivity of the abrasive grains 56 and the coating layer 58 has appropriate values. The average particle size of the abrasive grains 56 is preferably 1 to 60 μm. In FIG. 3, the conductive abrasive grains 54 are completely covered with the plating layer 60, but part of the abrasive grains 56 may be exposed due to wear of the plating layer 60 and the coating layer 58 by processing. . Further, as shown in FIG. 4, in order to improve the sharpness before processing, a part of the plating layer 60 and the coating layer 58 may be removed to expose a part of the abrasive grains 56. .

  The thickness of the coating layer 58 formed on the abrasive grains 56 is 10 μm or less, more preferably less than 0.1 μm, and still more preferably 0.05 μm or less. Alternatively, the mass of the coating layer 58 is preferably less than 10% of the mass of the abrasive grains 56, more preferably less than 5%.

  As a method for forming the coating layer on the surface of the abrasive grains, it can be formed using a CVD method, a PVD method, a plating method, a dipping method, or the like.

  FIG. 5 is a diagram showing a process of electrodepositing abrasive grains on the core of the wire according to the present embodiment. As shown in FIG. 5, the plating tank 64 is filled with a plating bath 66. The plating bath 66 is, for example, a sulfamic acid bath made of nickel sulfamate, nickel chloride, and boric acid. In the plating bath 66, conductive abrasive grains having a coating layer formed on the surface thereof are mixed. The core wire 50 is conveyed while being immersed in the plating bath 66 in the direction of the arrow in the figure. A part of the pulley that holds the core wire 50 serves as a cathode 68 and is applied with a negative potential. An anode 70 is provided so as to surround the core wire 50 immersed in the plating bath 66, and a positive potential is applied thereto.

  At the time of electrodeposition, a voltage is applied to the cathode 68 and the anode 70 while conveying the core wire 50 in the direction of the arrow. By using the conductive abrasive grains, the speed at which the abrasive grains are electrodeposited on the core wire 50 is increased, so that the conveying speed of the core wire 50 can be 1 m / min or more. For this reason, the time for electrodepositing the abrasive grains on the wire can be shortened, and the cost for producing the wire of the wire electric discharge machine can be reduced.

  Hereinafter, the operation of the wire electric discharge machine of the present embodiment will be described. As shown in FIG. 1, the workpiece W is placed on the work table 12, and the reels 26 and 28 are rotated by the traveling units 22 and 24 to cause the wire 20 to travel with respect to the workpiece W. A voltage is applied between the wire 20 and the workpiece W by the voltage application unit 38 while supplying the machining fluid from the machining fluid supply nozzles 44 and 46 to the machining portion of the workpiece W. Processing of the workpiece W is performed mainly by sparks caused by electric discharge generated between the wire 20 and the workpiece W.

  FIG. 6 is an enlarged view of the vicinity of the outer peripheral surface of a longitudinal section of a conventional wire. As shown in FIG. 6, in the wire 20 in which the conventional uncoated abrasive grains 56 are electrodeposited on the outer peripheral surface 58 of the core wire by the plating layer 60, the abrasive grains 56 do not have conductivity. It is not covered with the plating layer 60 and remains exposed. Therefore, if it is intended to electrodeposit the abrasive grains 56 with the required strength, it is necessary to increase the thickness of the plating layer 60, which requires time for electrodeposition. Further, even when a voltage is applied, the spark 62 due to the discharge hardly occurs in the vicinity of the non-conductive abrasive grains 56, and the spark is uneven. For this reason, a processing speed falls.

  On the other hand, as shown in FIG. 3, in the present embodiment, the conductive abrasive grains 54 themselves have conductivity, and most of the conductive abrasive grains 54 are covered with the plating layer 60. The spark 62 is less likely to be uneven. Therefore, machining efficiency by electric discharge is improved, and the machining speed can be improved. Even when the conductive abrasive 56 is quarried as shown in FIG. 4, only a part of the spark 62 is small, and compared with the case where abrasive particles having no conductivity are used, Unevenness can be made difficult to occur. The portion that cannot be completely processed by the electric discharge is mechanically processed by the conductive abrasive 54 that is electrodeposited on the traveling wire 20.

  The wire electric discharge machine and the wire electric discharge machining method of the present invention are not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the scope of the present invention.

It is a figure showing composition of a wire electric discharge machine concerning an embodiment of the present invention. It is a perspective view which shows a part of wire which concerns on this embodiment. It is the figure which expanded the outer peripheral surface vicinity of the longitudinal cross-section of the wire which concerns on this embodiment. It is a figure which shows a mode that the stone removal process was given to the abrasive grain of FIG. It is a figure which shows the process of electrodepositing a superabrasive grain on the core wire of the wire which concerns on this embodiment. It is the figure which expanded the outer peripheral surface vicinity of the longitudinal cross-section of the conventional wire.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Wire electric discharge machine, 12 ... Work table, 14, 16 ... Work table drive machine, 18 ... Work table drive part, 20 ... Wire, 22, 24 ... Traveling part, 26, 28 ... Reel, 30, 32, 34 , 36 ... guide pulley, 38 ... voltage application unit, 40 ... voltage application electrode, 42 ... machining fluid supply unit, 44, 46 ... machining fluid supply nozzle, 48 ... control unit, 50 ... core wire, 52 ... outer peripheral surface, 54 ... Conductive abrasive, 56 ... abrasive, 58 ... coating layer, 60 ... plating layer, 62 ... spark, 64 ... plating bath, 66 ... plating bath, 68 ... cathode, 70 ... anode, W ... workpiece.

Claims (3)

Holding means for holding the workpiece;
A wire for processing the workpiece;
Traveling means for traveling the wire relative to the workpiece;
Voltage application means for generating a discharge by applying a voltage between the wire and the workpiece;
With
The wire is electrodeposited with conductive abrasive grains on its surface,
Wire electric discharge machine. Holding means for holding the workpiece;
A wire for processing the workpiece;
Traveling means for traveling the wire relative to the workpiece;
Voltage application means for generating a discharge by applying a voltage between the wire and the workpiece;
With
The wire is electrodeposited with abrasive grains coated with a conductive material on its surface,
Wire electric discharge machine.   While running a wire electrodeposited with abrasive particles having conductivity on the surface, a voltage is applied between the wire and the workpiece to cause a discharge, thereby causing the workpiece to work. A wire electrical discharge machining method.

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