WO2001036709A1

WO2001036709A1 - Method and device for electric discharge surface treatment

Info

Publication number: WO2001036709A1
Application number: PCT/JP1999/006347
Authority: WO
Inventors: Akihiro Goto; Yasuhiro Kojima; Nagao Saito
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 1999-11-15
Filing date: 1999-11-15
Publication date: 2001-05-25
Also published as: TW469203B

Abstract

An electric discharge surface treatment method for forming a modified layer on the surface of an object (11) to be machined using an electrode for electric discharge surface treatment, in which the electrode and the object (11) are relatively moved, the modified layer (11a) is formed on the surface of the object (11) in a liquid by the discharge energy supplied between the electrode and the object (11), a wire electrode (12) and the modified layer (11a) are relatively moved, and the modified layer (11a) is shaped in the air using the discharge energy supplied between the wire electrode (12) and the modified layer (11a). Thus, a smoother modified layer (11a) is formed on the surface of the object (11).

Description

Description Discharge surface treatment method and apparatus

According to the present invention, a discharge layer is generated between a discharge surface treatment electrode and a workpiece, and the energy of the discharge causes a modified layer made of an electrode material or a substance in which the electrode material reacts with the discharge energy on the surface of the workpiece. Surface treatment method and apparatus for forming a modified layer comprising: a discharge surface treatment capable of forming a modified layer having good quality and smoother surface roughness on the surface of a workpiece; Method and apparatus improvements. Background art

Conventionally, as a technique for forming a modified layer on the surface of a workpiece to impart corrosion resistance and abrasion resistance, for example, a technique disclosed in Japanese Patent Application Laid-Open No. HEI 5-148615 is disclosed. There are surface treatment methods. This technology uses a green compact electrode, which is a discharge surface treatment electrode formed by mixing and compressing WC (tungsten carbide) powder and Co (cobalt) powder in a machining fluid. Processing (deposition processing), and then replacing the electrode with relatively low electrode wear such as copper electrode and performing secondary processing (remelting processing). is there. This method can form a modified layer with strong adhesion to steel, but forms a modified layer with strong adhesion to sintered materials such as cemented carbide. It is difficult.

However, according to our research, when a material that forms a hard carbide such as Ti (titanium) is used as an electrode for discharge surface treatment and a discharge is generated between the workpiece and a metal material, the process of remelting occurs. Without the need for a strong modified layer It has been found that it can be formed on certain metal surfaces. This is due to the reaction between the electrode material consumed by the electric discharge and C (carbon), which is a component of the machining fluid, to form TiC (titanium carbide). In addition, when a discharge is generated between a metal material as a workpiece and a compact powder electrode as a discharge surface treatment electrode made of a metal hydride such as TiH ₂ (titanium hydride), T It is known that a modified layer with higher adhesion can be formed more quickly than when a material such as i is used. Further, when a discharge is generated between a metal material as a workpiece by a green compact electrode which is an electrode for discharge surface treatment in which another metal or ceramic is mixed with a hydride such as T i H 2, It is said that a modified layer having various properties such as hardness and abrasion resistance can be quickly formed.

Such a method is disclosed, for example, in Japanese Patent Application Laid-Open No. 9-192937, and FIG. 4 shows a configuration example of a discharge surface treatment apparatus used for such a discharge surface treatment. explain. In the figure, 1 is T i H ₂ flour powder was compression molded formed by discharge surface treatment in which green compact electrode, 2 is the pressure E was 3 machining tank, four working fluid, 5 green A switching element for switching the voltage and current applied to the body electrode 1 and the workpiece 2; 6, a control circuit for controlling the on / off of the switching element 5; 7, a power supply; 8, a resistor; and 9, a formed circuit. This is a modified layer. With such a configuration, the green compact electrode 1 and the workpiece 2 are relatively moved by the X-axis drive unit, the Y-axis drive unit, and the Z-axis drive unit, which are not shown, and are relatively moved. A discharge is generated between the workpiece 2 and the discharge energy, whereby the modified layer 9 can be formed on the surface of the workpiece 2 made of steel, cemented carbide, or the like.

A method of forming a modified layer made of carbide on the surface of a workpiece by such a discharge surface treatment is performed in a working fluid as described below. That is, the carbide that is a component of the modified layer to be formed is combined with the component of the discharge surface treatment electrode. Either forming a modified layer made of carbide on the workpiece by the heat energy from the discharge, or applying a metal or a compound of the metal that forms carbide that is a component of the formed modified layer to an electrode for discharge surface treatment As a component of this, the heat energy from the discharge is used to react with carbon, which is a component of the machining fluid, to form a reformed layer made of carbide on the workpiece.

In such a discharge surface treatment, when the modified layer on the surface of the workpiece is observed, irregularities are observed in the modified layer formed on the workpiece, and a smooth surface property may not always be obtained. . This indicates that the surface roughness of the modified layer formed on the workpiece by the discharge surface treatment is rough. The reason for this is that it is necessary to form a modified layer with a certain thickness or more in a short time in order to secure the quality of the modified layer formed on the workpiece, such as hardness and adhesion strength. This is because, under the electric discharge machining conditions for realizing this, the surface roughness of the modified layer formed on the workpiece tends to be rough.

As described above, the conventional discharge surface treatment method exclusively uses in-liquid discharge, and depending on only in-liquid discharge, the composition of the electrode material for discharge surface treatment used and the discharge machining conditions during discharge surface treatment. Thus, the surface roughness of the modified layer formed on the workpiece can only be slightly improved. Therefore, the conventional discharge surface treatment method has a problem that a modified layer having good quality and smoother surface roughness cannot be formed.

In addition, when the surface roughness of the modified layer formed on the workpiece becomes rough, for example, when the workpiece is a punching die, burrs are formed on the molded product, and the workpiece becomes an extrusion die. In the case of (punch), defects such as streaks occur in the molded product. Disclosure of the invention

The present invention has been made to solve the above problems. Another object of the present invention is to provide a discharge surface treatment method and apparatus capable of forming a high-quality and smoother modified layer on the surface of a workpiece.

The discharge surface treatment method according to the present invention is a discharge surface treatment method for forming a modified layer on the surface of a workpiece by discharge machining using an electrode for discharge surface treatment. The object is relatively moved, and in a liquid, a modified layer is formed on the surface of the workpiece by discharge energy supplied between the discharge surface treatment electrode and the workpiece. And the modified layer are relatively moved, and the modified layer is shaped by discharge energy supplied between the wire electrode and the modified layer in the air.

The modified layer is formed by discharging energy supplied between the wire electrode and the modified layer in an atmosphere of a nitrogen gas, a nitrogen compound gas, or a mixed gas of a nitrogen compound gas and a nitrogen gas. It is to shape.

An electric discharge surface treatment apparatus according to the present invention is an electric discharge surface treatment apparatus for forming a modified layer on a surface of a workpiece by electric discharge machining using an electric discharge surface treatment electrode. A relative movement means capable of relatively moving the workpiece; a discharge generating means for supplying discharge energy between the discharge surface treatment electrode or the wire electrode and a pole between the workpiece; Wire electrode traveling means for feeding a workpiece, machining fluid supply means for supplying a machining fluid for immersing the workpiece, and discharge machining between the wire electrode and the workpiece. And a working fluid discharging means for discharging the working fluid in order to perform the process.

Further, an injection means for supplying a nitrogen gas, a nitrogen compound gas, or a mixed gas of a nitrogen compound gas and a nitrogen gas into a gap between the wire electrode and the workpiece.

A chamber covering the workpiece; nitrogen gas in the chamber; A supply means for supplying a nitrogen compound gas or a mixed gas of a nitrogen compound gas and a nitrogen gas.

Since the present invention is configured as described above, there is an effect that a high quality and smoother modified layer can be formed on the surface of the workpiece. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a configuration diagram showing a discharge surface treatment apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram showing a discharge surface treatment apparatus according to Embodiment 2 of the present invention.

FIG. 3 is a configuration diagram showing a discharge surface treatment apparatus according to Embodiment 2 of the present invention.

FIG. 4 is a configuration diagram of a conventional discharge surface treatment apparatus. BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1

FIG. 1 is a configuration diagram showing a discharge surface treatment apparatus according to Embodiment 1 of the present invention, where 11 is a die material such as a punching die, an extrusion die, etc. A wire electrode, 13 is a table surface on which the workpiece 11 is placed, 14 and 15 are X and Y tables arranged orthogonal to each other so as to move in a two-dimensional direction, and 16 is An X-axis driving device for driving the X-table 14, 17 is a Y-axis driving device for driving the Y-table 15, and the X-axis driving device 16 and the Y-axis driving device 17 are provided with the workpiece 11. It constitutes a relative moving means for relatively changing the positional relationship with the wire electrode 12. As the relative moving means, the relative moving means described in the background art can be used. Also, 18 is a numerical controller, 19 is a numerical controller 18 Locus movement control means provided therein, 20a is a wire reel, 2Ob is a wire drive roller, and the wire reel 20a and the wire drive roller 20b constitute wire electrode running means. I have. Reference numeral 21 denotes a power supply device which is a discharge generating means for supplying discharge energy between the workpiece 11 and the wire electrode 12, and includes a DC power supply, a switching element, a control circuit, and the like. .

The workpiece 11 is subjected to a discharge surface treatment in a machining fluid using, for example, the side surface of the electrode for discharge surface treatment by a discharge surface treatment apparatus having a configuration as shown in FIG. 4 shown in the background art. A modified layer 11 a is formed on a predetermined portion of the workpiece 11. In this way, after forming the modified layer 11a on the workpiece 11 in the working fluid, the working fluid is discharged by a working fluid discharge unit (not shown) capable of discharging the working fluid by, for example, opening a valve. Next, as shown in FIG. 1, an X-axis driving device 16 and a Y-axis driving device constituting a relative moving means between the modified layer 11 a formed on the workpiece 11 and the wire electrode 12. The gap is adjusted to a predetermined value by 17 and the wire electrode 12 is run by a wire reel 20a, a wire drive roller 20b, etc., which constitutes the wire electrode running means, and is provided in the numerical controller 18 Based on a command from the trajectory movement control means 19, the wire electrode 12 is moved along the modified layer surface of the workpiece 11 by the X-axis drive device 16 and the Y-axis drive device constituting the relative movement means. The trajectory is moved, and a discharge energy is supplied between the workpiece 11 and the wire electrode 12 by the power supply device 21 which is a discharge generating means, and is processed between the modified layer 11 a and the wire electrode 12. Discharge is generated in the air without passing through the liquid, and the surface of the modified layer 11a is removed. Next, the reason why the electric discharge machining using the wire electrode is performed in the air in the present invention will be described.

When performing EDM in a machining fluid, the machining fluid is less compressible than gas, so the discharge generates a large discharge explosion pressure, Since the wire electrode between the guides vibrates, it is not possible to perform more precise processing. Due to such characteristics of the machining fluid, electric discharge machining using a wire electrode in the machining fluid is performed by a modified layer (having a thickness of several m to several m) formed on the workpiece by the discharge surface treatment targeted by the present invention. It is not suitable for processing to reduce the surface roughness (for example, the maximum height is about several meters or less).

Therefore, in the present invention, electric discharge machining in the air is employed, and by performing electric discharge machining with the wire electrode 12 in the air, the machining reaction force becomes extremely small. Vibration is suppressed, and higher precision processing can be performed. Therefore, the modified layer 11a can be shaped more smoothly, and the surface roughness of the modified layer 11a can be reduced.

After the series of discharge surface treatment operations according to the present invention has been completed, when performing the same operation on another workpiece, it is necessary to immerse the workpiece in the working fluid. The supply of the processing liquid can be performed by, for example, supplying the processing liquid into the processing tank by a processing liquid supply unit including a pump or the like.

As described above, electric discharge machining is performed on the modified layer formed on the workpiece by electric discharge surface treatment in the machining fluid as the primary machining, and further, in the air using the wire electrode in the air as the secondary machining. Accordingly, it is possible to form a modified layer having good quality and smoother surface roughness.

Embodiment 2

FIG. 2 is a configuration diagram showing a discharge surface treatment apparatus according to Embodiment 2 of the present invention. The same reference numerals as in FIG. 1 of Embodiment 1 indicate the same or corresponding parts. In FIG. 2, reference numeral 22 denotes injection means, and reference numeral 23 denotes nitrogen gas, nitrogen compound gas such as ammonia gas, or a mixed gas of nitrogen compound gas and nitrogen gas injected by the injection means 22. Fig. 2 It has a configuration in which 22 injection means are added in the vicinity of the gap between the reformed layer 11a and the wire electrode 12. Nitrogen gas, nitrogen compound gas, or nitrogen compound gas and nitrogen introduced from a supply source (not shown) The gas mixture 23 is injected and supplied by the injection means 22 into the gap between the reformed layer 11a of the workpiece 11 and the wire electrode 12 to supply nitrogen gas, nitrogen compound gas, or nitrogen compound gas. And electrical discharge machining (secondary machining described in Embodiment 1) in an atmosphere of a mixed gas of nitrogen and nitrogen gas.

According to such a method, similarly to Embodiment 1, the surface roughness of the modified layer 11a can be reduced, and a nitrogen compound is further formed on the surface of the modified layer 11a. Therefore, the wear resistance of the workpiece 11 can be improved.

Fig. 3 shows the minimum opening required for the relative movement of the work 11 and the X table 14 and the Y table 15 on the X table 14 to cover the work 11 in Fig. 2. It is a figure which shows the state which attached the chamber 24 which has a gas, and 25 is a supply means of the nitrogen gas, the nitrogen compound gas, or the mixed gas of the nitrogen compound gas and the nitrogen gas. The supply means 25 is provided with a flow rate adjusting means capable of arbitrarily adjusting the gas supply amount to the chamber 24.

In the atmosphere of the nitrogen gas or the nitrogen compound gas or the mixed gas of the nitrogen compound gas and the nitrogen gas filled in the chamber 24, the modified layer 11a of the workpiece 11 and the wire electrode 12 are The same effect as in the configuration of FIG. 2 can be obtained more efficiently by discharging the battery between the two. Industrial applicability

As described above, the discharge surface treatment method and apparatus according to the present invention are suitable for being used in a surface treatment related industry for forming a modified layer on the surface of a workpiece.

Claims

The scope of the claims

1. In a discharge surface treatment method of forming a modified layer on the surface of a workpiece by electric discharge machining using an electrode for discharge surface treatment,

The electrode for discharge surface treatment and the workpiece are relatively moved to each other, and in a liquid, the surface of the workpiece is formed by discharge energy supplied between the electrode for discharge surface treatment and the workpiece. After forming the modified layer on

A discharge characterized by relatively moving a wire electrode and the modified layer, and shaping the modified layer by discharge energy supplied between the wire electrode and the modified layer in the air. Surface treatment method.

2. The discharge surface treatment method according to claim 1, wherein the air is an atmosphere of a nitrogen gas, a nitrogen compound gas, or a mixed gas of a nitrogen compound gas and a nitrogen gas.

3. In a discharge surface treatment apparatus that forms a modified layer on the surface of a workpiece by electric discharge machining using an electrode for discharge surface treatment,

Relative movement means capable of relatively moving the discharge surface treatment electrode or wire electrode and the workpiece;

Discharge generating means for supplying discharge energy between the electrode for the discharge surface treatment or the wire electrode and the workpiece;

Wire electrode running means for feeding the wire electrode to the workpiece,

A machining fluid supply means for supplying a machining fluid to immerse the workpiece, and a machining fluid discharge means for discharging a machining fluid for performing electric discharge machining between the wire electrode and the workpiece in the air. Discharge surface treatment characterized by comprising:

4. The gap between the wire electrode and the workpiece according to claim 3. And a discharge means for supplying a nitrogen gas, a nitrogen compound gas, or a mixed gas of a nitrogen compound gas and a nitrogen gas.

5. The method according to claim 3, further comprising: a chamber that covers the workpiece; and a supply unit that supplies a nitrogen gas, a nitrogen compound gas, or a mixed gas of a nitrogen compound gas and a nitrogen gas into the chamber. Discharge surface treatment equipment.