JP2005329504A - Electrode wire for wire electric discharge machining and object machined by electric discharge manufactured by using the electrode wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode wire for wire electric discharge machining capable of improving corrosion resistance of a working surface of a workpiece only if performing electric discharge machining, and an object machined by electric discharge manufactured by using the electrode wire. <P>SOLUTION: This electrode wire 10 has at least one coating layer 12 around a core material 11. At least an outermost layer of the coating layer 12 is a Ni or Ni alloy layer, a Fe or Fe alloy layer, a Fe-Cr-Ni alloy layer, or a Fe-Cr alloy layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrode wire used for wire electric discharge machining.

  Cu-Zn alloy electrode wires are utilized as electrode wires for wire electric discharge machining. This electrode wire has excellent discharge characteristics such as processing speed and processing accuracy, and also has advantageous characteristics in terms of cost.

  Until now, a single alloy wire (Cu-35 wt% Zn alloy (65/35 brass)) containing 32-36 wt% Zn has been used as this type of electrode wire. In the processing electrode wire, high-speed workability is particularly emphasized. For this reason, a coated electrode wire for electric discharge machining has been proposed in which a Cu—Zn alloy layer having a higher Zn concentration than the conventional one is coated around a core material made of Cu or Cu alloy (for example, Patent Document 1). reference).

  In addition, as a method of modifying the machining surface of a workpiece (hereinafter referred to as a workpiece) by electric discharge machining, the workpiece is placed in the machining fluid and silicon is mixed in the machining fluid in a powdered state. A method of forming a film on the processed surface has been proposed (see, for example, Patent Document 2).

Japanese Patent No. 2541638 Japanese Patent Laid-Open No. 2-83119

  In recent years, workpieces manufactured using an electrode wire for wire electric discharge machining have been required to add functions such as corrosion resistance and improve production efficiency. Usually, constituent elements (specifically, Cu, Zn, etc.) of the electrode wire for wire electric discharge machining adhere to the processed surface of the workpiece. However, some workpieces dislike that Cu, Zn or the like is attached to the processed surface. Examples of such a work include medical instruments, specifically, surgical instruments that come into contact with the body, and implant members that are inserted or implanted in the body. Since Cu, Zn, and the like are metal elements that easily cause metal allergy, it is not preferable that they adhere to the surface of a medical device.

  The conventional general-purpose single alloy wire (65/35 brass wire) and the electrode wire described in Patent Document 1 are intended to improve the processing speed and the accuracy of the workpiece processing surface. For this reason, in the work manufactured using these electrode wires, after wire electric discharge machining, surface treatment of the work is performed in a separate process to improve the corrosion resistance of the work work surface, Cu attached to the work work surface, Zn was removed. As a result, there has been a problem that the production efficiency of the workpiece is deteriorated, and as a result, the production cost of the workpiece is increased.

  Although the method described in Patent Document 2 can form a film on the workpiece machining surface, it requires a step of mixing silicon powder into the machining fluid, and therefore there is a problem that the number of steps required for electric discharge machining increases. there were. In addition, this method requires a circulation device for uniformly dispersing the silicon powder in the processing liquid, and thus has a problem of increasing the device cost. Furthermore, this method is mainly applied to a die engraving machine for processing a mold or the like, and does not use a wire-shaped (or linear) electrode. Therefore, it has been difficult to process a lead frame die that requires fine processing or a thick workpiece.

  The object of the present invention created in view of the above circumstances is to provide an electrode wire for wire electric discharge machining that can improve the corrosion resistance of a workpiece machining surface only by performing electric discharge machining, and an electric discharge workpiece manufactured using the wire. It is to provide.

  In order to achieve the above object, an electrode wire for wire electric discharge machining according to the present invention is an electrode wire for wire electric discharge machining having at least one coating layer around a core material. A layer, an Fe or Fe alloy layer, an Fe—Cr—Ni alloy layer, or an Fe—Cr alloy layer is provided.

  Here, the Fe—Cr—Ni alloy layer is preferably formed of austenitic stainless steel. The Fe—Cr alloy layer is preferably formed of martensitic stainless steel or ferritic stainless steel.

  Moreover, it is preferable that ratio (t / D) of the layer thickness t of a coating layer and the diameter D of the whole electrode wire is 0.10-0.30.

The heartwood is
Pure Cu wire,
Cu-0.02 to 0.2 wt% Zr alloy wire,
Cu-0.15-0.25 wt% Sn-0.15-0.25 wt% In alloy wire,
Cu-0.15-0.70 wt% Sn alloy wire,
Cu-0.15-0.70 wt% In alloy wire,
Cu-5-30 wt% Zn alloy wire,
An alloy wire obtained by adding at least one of Zr, Cr, Si, Mg, Al, Fe, P, Ni, Ag, and Sn to Cu-5 to 30 wt% Zn,
Cu-0.2 to 20% by weight Ag alloy wire,
Fe-based alloy wire,
Copper coated steel wire,
Copper alloy coated steel wire,
Or copper and copper alloy coated composite wire,
Consists of.

  On the other hand, the electric discharge machined object according to the present invention performs electric discharge machining on the workpiece using the aforementioned wire electric discharge machining electrode wire, and a coating layer of the wire electric discharge machining electrode wire is formed on the processed surface of the workpiece. A metal or alloy film constituting the outermost layer is formed.

  The wire electrode for wire electric discharge machining according to the present invention exhibits an excellent effect that the corrosion resistance of the workpiece machining surface can be improved only by performing electric discharge machining using the electrode wire.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of the invention will be described with reference to the accompanying drawings.

  FIG. 1 shows a cross-sectional view of a wire electric discharge machining electrode wire according to a preferred embodiment of the present invention.

  As shown in FIG. 1, the wire electric discharge machining electrode wire 10 according to the present embodiment has at least one coating layer 12 around a core material 11. At least the outermost layer of the coating layer 12 is composed of a Ni or Ni alloy layer, a Fe or Fe alloy layer, a Fe—Cr—Ni alloy layer, or a Fe—Cr alloy layer. In FIG. 1, the entire coating layer 12 is composed of Ni or Ni alloy, Fe or Fe alloy, Fe—Cr—Ni alloy, or Fe—Cr alloy.

  Here, as the Fe—Cr—Ni alloy, austenitic stainless steel is preferable, and examples thereof include SUS304 and SUS316L (so-called surgical stainless steel).

  As the Fe—Cr alloy, nickel-free stainless steel, for example, martensitic stainless steel or ferritic stainless steel is preferable. Examples of martensitic stainless steel include SUS410. Examples of the ferritic stainless steel include SUS430.

  The ratio (t / D) between the layer thickness t of the coating layer 12 and the diameter D of the entire wire electric discharge machining electrode wire 10 is 0.10 to 0.30, preferably 0.15 to 0.25. The layer thickness t of the coating layer 12 is appropriately determined according to the diameter D of the wire electric discharge machining electrode wire 10, and is Ni or Ni alloy, Fe or Fe alloy, Fe—Cr—Ni alloy, or Fe—Cr alloy. The outermost layer to be formed preferably has a layer thickness of at least 2 μm. Here, if t / D is less than 0.10, the coating layer 12 is consumed and the core material 11 is exposed before the coating (described later) is formed on the workpiece machining surface during electric discharge machining, and the workpiece machining is performed. This is because the constituent elements (Cu, Zn, etc.) of the core material adhere to the surface. Further, when t / D exceeds 0.30, the discharge characteristics of the wire electric discharge machining electrode wire 10 are remarkably deteriorated.

  The covering layer 12 is formed so that the layer thickness is uniform over the circumferential direction of the core material 11. For example, the surface roughness of the coating layer 12 is adjusted so that the maximum height Rmax is 10 to 500 nm. As a result, at the time of electric discharge machining using the wire electric discharge machining electrode wire 10, electric discharge can be uniformly generated between the workpiece and the wire electric discharge machining electrode wire 10 over the entire circumference in the circumferential direction of the electrode wire. .

The core material 11 is made of a highly conductive and heat resistant material. As the core material 11, for example,
Pure Cu wire,
Cu-0.02 to 0.2 wt% Zr alloy wire,
Cu-0.15-0.25 wt% Sn-0.15-0.25 wt% In alloy wire,
Cu-0.15-0.70 wt% Sn alloy wire,
Cu-0.15-0.70 wt% In alloy wire,
Cu-5-30 wt% Zn alloy wire,
An alloy wire obtained by adding at least one of Zr, Cr, Si, Mg, Al, Fe, P, Ni, Ag, and Sn to Cu-5 to 30 wt% Zn,
Cu-0.2 to 20% by weight Ag alloy wire,
Fe-based alloy wire,
Copper coated steel wire,
Copper alloy coated steel wire,
Or copper and copper alloy coated composite wire,
Consists of. Here, as the Fe-based alloy, one having high conductivity is preferable. By constituting the core material 11 with these wires, the electrical conductivity of the wire electric discharge machining electrode wire 10 can be improved, and the discharge characteristics can be improved.

  Although the case where the coating layer 12 of the wire electric discharge machining electrode wire 10 has a single-layer structure has been described in the present embodiment, the present invention is not limited to this. For example, when the coating layer 12 has a multilayer structure of two or more layers, the outermost layer may be a Ni or Ni alloy layer, a Fe or Fe alloy layer, a Fe—Cr—Ni alloy layer, or a Fe—Cr alloy layer. .

  Next, the operation of the wire electric discharge machining electrode wire 10 according to the present embodiment will be described.

First, the wire electric discharge machining electrode wire 10 according to the present embodiment is manufactured by a method such as an extrusion method, a plating method, or a pipe making method described below.
(1) After a roughing wire composed of the core material 11 is inserted into a pipe made of a metal or alloy constituting the coating layer 12 to form a billet, the billet is subjected to diameter reduction processing (extrusion processing) ( Extrusion method).
(2) A metal or alloy plating film constituting the coating layer 12 is formed around the rough wire formed of the core material 11, and then the plating wire is subjected to diameter reduction processing (plating method).
(3) A strip of metal or alloy constituting the covering layer 12 is vertically attached around the rough drawing line composed of the core material 11 (formed into a tubular shape by roll forming), and then extends in the longitudinal direction of the tubular material. After welding the opening to form a welded pipe, the welded pipe is subjected to diameter reduction processing (pipemaking method).

  Electric discharge machining (cutting) is performed on a workpiece (not shown) using the wire electric discharge machining electrode wire 10 manufactured by the above method or the like. Specifically, by applying a voltage between the workpiece and the wire electric discharge machining electrode wire 10 (wire electrode), an electric discharge is generated between the workpiece and the wire electrode. The coating energy 12 of the wire electric discharge machining electrode wire 10 is melted and evaporated by the discharge energy, and is welded to the workpiece machining surface. As a result, a film made of a metal or an alloy constituting the coating layer 12 is formed on the entire work surface, and an electric discharge machined product is obtained.

  As the workpiece, any conventional material that can be cut by wire electric discharge machining can be applied, and examples thereof include tool steel and bearing steel.

  The electric discharge machining is performed under such a condition that at least the outermost layer of the coating layer 12 is not completely consumed during the electric discharge machining. For example, when the outermost layer is thick, the outermost layer is hardly consumed even when a high voltage is applied (loading a high output). Conversely, when the outermost layer is thin, when the high voltage is applied (when a high output is applied), the outermost layer is quickly consumed. Therefore, electric discharge machining is performed while adjusting the applied voltage value according to the thickness of the outermost layer.

  The electrode wire 10 for wire electric discharge machining according to the present embodiment has a coating layer 12 in which at least the outermost layer is made of a metal or alloy having excellent corrosion resistance on the outer periphery of a core material 11 having high conductivity and high heat resistance. Is provided. Using this wire electric discharge machining electrode wire 10, electric discharge machining (cutting) is performed on a workpiece (not shown). Specifically, by applying a voltage between the workpiece and the wire electric discharge machining electrode wire 10 (wire electrode), an electric discharge is generated between the workpiece and the wire electrode. Due to the discharge energy, the coating layer 12 of the wire electric discharge machining electrode wire 10 is melted and evaporated, and the metal or alloy constituting the coating layer 12 is transferred (welded) to the workpiece processing surface as a consumable powder. As a result, a film made of a metal or an alloy constituting the coating layer 12 is first formed on the work surface.

  This coating prevents Cu and Zn, which are constituent elements of the core material 11 of the electrode wire 10 for wire electric discharge machining, from adhering to the workpiece machining surface during subsequent electric discharge machining. Therefore, there is no adhesion of Cu or Zn on the work surface after electric discharge machining. As a result, it is not necessary to perform a deposit removal process on the workpiece after the electric discharge machining (electric discharge machined product).

  Moreover, since the metal or alloy which comprises this film has the outstanding corrosion resistance, surface modification of a workpiece processing surface is made | formed by formation of a coating film, and the corrosion resistance of a workpiece processing surface improves. This coating is formed on the workpiece machining surface simultaneously with the wire electric discharge machining. Therefore, it is not necessary to subject the workpiece after the electric discharge machining to a surface modification treatment on the workpiece machining surface, and an electric discharge machining product subjected to the surface modification treatment can be obtained easily and inexpensively.

  In addition, the wire electric discharge machining electrode wire 10 according to the present embodiment can perform complicated fine machining on a workpiece as in the case of a conventional wire electric discharge machining electrode wire, and can also handle a thick workpiece. Electric discharge machining is possible. Therefore, the electrode wire 10 for wire electric discharge machining can be easily applied to a lead frame die that requires fine machining or a workpiece having a thickness of 300 mm or more.

  As described above, according to the electrode wire 10 for wire electric discharge machining according to the present embodiment, electric discharge machining can be performed with the same or substantially the same discharge characteristics as the conventional electrode wire, and the workpiece machining surface is simultaneously formed with the electric discharge machining. Surface modification treatment (formation treatment of a corrosion-resistant film) can also be performed. For this reason, the surface modification treatment for the electric discharge workpiece is not necessary, and the productivity of the electric discharge workpiece can be greatly improved. As a result, it is possible to reduce the production cost of the electric discharge machined object.

  Moreover, in the obtained electric discharge machined object, the film formed on the workpiece machining surface prevents Cu and Zn from adhering to the workpiece machining surface during electric discharge machining. For this reason, when the electric discharge machined object to be manufactured is a medical instrument, the electric discharge machined object can be used as a product in a state as it is after electric discharge machining, without performing Cu or Zn removal treatment on the electric discharge machined object. it can.

  Here, when the purpose is only to improve the corrosion resistance of the workpiece surface of the electric discharge workpiece, the metal or alloy constituting at least the outermost layer of the coating layer 12 of the electrode wire 10 for wire electric discharge machining may be Ni or Ni alloy, Any of Fe or Fe alloy, Fe—Cr—Ni alloy, and Fe—Cr alloy may be used. On the other hand, when the electric discharge machined object is a medical instrument, the metal or alloy constituting at least the outermost layer of the coating layer 12 of the electrode wire 10 for wire electric discharge machining can be Fe or Fe alloy, surgical stainless steel (Fe-Cr). -Ni alloy) and Fe-Cr alloy are preferable, more preferably surgical stainless steel and Fe-Cr alloy.

  As described above, the present invention is not limited to the above-described embodiment, and it goes without saying that various other things are assumed.

  Next, although this invention is demonstrated based on an Example, this invention is not limited to this Example.

(Example 1)
Using a Cu-0.19Sn-0.2In alloy wire (unit: wt%) with a diameter of 4.0mm as the core material, this core material is inserted into a Ni pipe with a thickness of 0.5mm, and then wire drawing and heat treatment are repeated. Thus, an electrode wire for wire electric discharge machining having a wire diameter of 0.25 mm was produced.

(Example 2)
Using the same core material as in Example 1, this core material was inserted into a 0.5 mm thick stainless steel pipe (made of SUS304), and then wire drawing and heat treatment were repeated, so that a wire discharge with a wire diameter of 0.25 mm was performed. A processing electrode wire was prepared.

(Conventional example 1)
An electrode wire for wire electric discharge machining having a diameter of 0.25 mm was made of a single alloy of Cu-35Zn (unit: wt%).

  Table 1 shows the core composition, the coating layer material, the electric discharge machining speed, the corrosion resistance, and the presence or absence of adhesion of Cu and Zn in the wire electric discharge machining electrode wires of Examples 1 and 2 and Conventional Example 1.

  The electric discharge machining speed is measured by using the electrode wires of Examples 1 and 2 and Conventional Example 1 made of steel (SKD-11 [JIS standard]) and performing electric discharge machining on a workpiece having a thickness of 50 mm. Measured with Here, the electric discharge machining speed is a relative value when the electric discharge machining speed of the electrode wire for wire electric discharge machining of Conventional Example 1 is 1.0.

  The corrosion resistance was evaluated by immersing each workpiece after electric discharge machining in aqua regia for 5 minutes and observing the appearance of the corrosion of the workpiece. Here, the evaluation of the corrosion resistance was evaluated as ◯ when no corrosion was observed, Δ when some corrosion was observed, and X when corrosion was significant.

  As shown in Table 1, each of the wire electric discharge machining electrode wires of Examples 1 and 2 was 5 to 8% lower in electric discharge machining speed than the wire electric discharge machining electrode wire of Conventional Example 1.

  By the way, in the workpiece subjected to the electric discharge machining using the wire electric discharge machining electrode wire of Conventional Example 1, significant corrosion was observed. On the other hand, in the workpiece subjected to the electric discharge machining using the wire electric discharge machining electrode wires of Examples 1 and 2, almost no corrosion was observed, and in particular, the wire electric discharge machining electrode wire of Example 2 was used. No corrosion was observed in the workpieces that were subjected to EDM. That is, by performing electric discharge machining of the workpiece using the wire electric discharge machining electrode wires of Examples 1 and 2, a coating having excellent corrosion resistance was formed on the workpiece machining surface.

  Moreover, in the workpiece | work which performed the electrical discharge machining using the electrode wire for wire electrical discharge machining of the prior art example 1, Cu and Zn had adhered to the process surface. On the other hand, Cu and Zn did not adhere to the workpiece machining surface at all in the workpiece subjected to electric discharge machining using the wire electric discharge machining electrode wires of Examples 1 and 2. In other words, by performing electric discharge machining of the workpiece using the wire electric discharge machining electrode wires of Examples 1 and 2, the coating formed on the workpiece machining surface prevents Cu and Zn from adhering to the workpiece machining surface. did.

It is a cross-sectional view of an electrode wire for wire electric discharge machining according to a preferred embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electrode wire for wire electric discharge machining 11 Core material 12 Coating layer

Claims (9)

  A wire electric discharge machining electrode wire having at least one coating layer around a core material, wherein a Ni or Ni alloy layer is provided on the outermost layer of the coating layer.   A wire electric discharge machining electrode wire having at least one coating layer around a core material, wherein an Fe or Fe alloy layer is provided on the outermost layer of the coating layer.   A wire electric discharge machining electrode wire having at least one coating layer around a core material, wherein an Fe-Cr-Ni alloy layer is provided on the outermost layer of the coating layer.   The electrode wire for wire electric discharge machining according to claim 3, wherein the Fe-Cr-Ni alloy layer is formed of austenitic stainless steel.   A wire electric discharge machining electrode wire having at least one coating layer around a core material, wherein an Fe-Cr alloy layer is provided on the outermost layer of the coating layer.   The electrode wire for wire electric discharge machining according to claim 5, wherein the Fe-Cr alloy layer is formed of martensitic stainless steel or ferritic stainless steel.   The electrode wire for wire electric discharge machining according to any one of claims 1 to 6, wherein a ratio (t / D) between a layer thickness t of the covering layer and a diameter D of the entire electrode wire is 0.10 to 0.30. The heartwood is
Pure Cu wire,
Cu-0.02 to 0.2 wt% Zr alloy wire,
Cu-0.15-0.25 wt% Sn-0.15-0.25 wt% In alloy wire,
Cu-0.15-0.70 wt% Sn alloy wire,
Cu-0.15-0.70 wt% In alloy wire,
Cu-5-30 wt% Zn alloy wire,
An alloy wire obtained by adding at least one of Zr, Cr, Si, Mg, Al, Fe, P, Ni, Ag, and Sn to Cu-5 to 30 wt% Zn,
Cu-0.2 to 20% by weight Ag alloy wire,
Fe-based alloy wire,
Copper coated steel wire,
Copper alloy coated steel wire,
Or copper and copper alloy coated composite wire,
The electrode wire for wire electric discharge machining according to any one of claims 1 to 7, comprising: 9. An electric discharge machining is performed on a workpiece using the wire electric discharge machining electrode wire according to claim 1, and an outermost layer of a coating layer of the wire electric discharge machining electrode wire is formed on a machining surface of the workpiece. An electric discharge machined product formed by forming a metal or alloy film.

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