WO2001005545A1

WO2001005545A1 - Discharge surface treating electrode and production method thereof

Info

Publication number: WO2001005545A1
Application number: PCT/JP1999/003830
Authority: WO
Inventors: Akihiro Goto; Toshio Moro
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 1999-07-16
Filing date: 1999-07-16
Publication date: 2001-01-25
Also published as: CH694120A5; DE19983550T1; DE19983550B4

Abstract

A practical-use discharge surface treating electrode (10) having a proper strength and safety and being easy to crumble and used for discharge surface treating for forming a hard coat on the surface of an untreated material by discharge energy produced between the electrode and the untreated material, wherein a production method thereof comprises the steps of mixing TiC powder (11) as metal carbide powder with TiH2 powder (12) as metal hydride powder, compression-molding the mixture and heat-treating the molded product to release hydrogen in the TiH2 powder (12) and obtain Ti powder (13).

Description

Description Electrode for surface treatment of electric discharge and manufacturing method thereof

According to the present invention, a discharge is generated between an electrode and a material to be treated, and the energy causes a hard film made of an electrode material or a hard film made of a substance in which the electrode material reacts with discharge energy on the surface of the material to be treated. The present invention relates to an electrode for discharge surface treatment to be formed and used for a discharge surface treatment operation, and to an improvement in a manufacturing method thereof. Background art

Conventionally, techniques for forming a hard coating on the surface of a material to be treated to impart corrosion resistance and abrasion resistance include, for example, a discharge surface disclosed in Japanese Patent Application Laid-Open No. 5-148686. There is a processing method. In this technology, primary processing (deposition processing) is performed using a green compact electrode formed by mixing and compressing WC (tungsten carbide) powder and Co (cobalt) powder. This is a two-step discharge surface treatment method for metallic materials, in which the electrode is replaced with an electrode with relatively low electrode wear and secondary processing (remelting processing) is performed. This method can form a hard coating with strong adhesion to steel, but forms a hard coating with strong adhesion to sintered materials such as cemented carbide. It is difficult.

However, according to our research, if a material that forms a hard carbide such as Ti (titanium) is used as an electrode and a discharge is generated between the material to be treated and a metal material, a strong It has been found that a hard coating can be formed on the surface of the metal to be treated. This is due to the power consumed by the discharge. This is due to the reaction between the electrode material and carbon, a component in the working fluid, to form TiC (titanium carbide). In addition, when a discharge is generated between the metal material to be processed by the compacted electrode of a metal hydride such as Ti H ₂ (titanium hydride), it is more difficult than when using a material such as Ti. However, it has been found that a hard coating film having high adhesion can be formed quickly. Furthermore, if a discharge is generated between the metal material as the material to be processed by the compacted electrode in which other metals or ceramics are mixed with a hydride such as TiH2, the hardness, abrasion resistance, etc. It has been shown that hard coatings with various properties can be formed quickly.

Such a method is disclosed in, for example, Japanese Patent Application Laid-Open No. 9-192937, and a configuration example of an apparatus used for such a discharge surface treatment will be described with reference to FIG. In the figure, 1 is a green compact electrode formed by compression molding of TiH2 powder, 2 is a material to be processed, 3 is a processing tank, 4 is a working fluid, and 5 is a green compact electrode 1 and a material 2 to be processed. A switching element for switching applied voltage and current, 6 is a control circuit for controlling on / off of the switching element 5, 7 is a power supply, 8 is a resistor, and 9 is a formed hard coating. With such a configuration, a discharge is generated between the green compact electrode 1 and the material 2 to be processed, and a strong adhesive force to the surface of the material 2 to be processed, such as steel or cemented carbide, is generated by the discharge energy. It is possible to form the hard coating 9 having the following.

Electrodes used in such a discharge surface treatment are difficult to handle without a certain degree of strength, and the electrodes are excessively disintegrated due to the discharge energy during the discharge surface treatment, and the electrode material is exposed to the surface of the material to be treated. There is a problem that it cannot be adhered in a molten state. In addition, when the strength of the electrode is high and the electrode is too hard, there is a problem that the electrode is not easily collapsed by discharge energy at the time of the discharge surface treatment, and the treatment efficiency is reduced. Therefore, The electrode for discharge surface treatment is required to have appropriate strength and fragility. Materials with such properties include metal hydrides, but there is a safety problem due to the danger of spontaneous ignition when exposed to water. Therefore, a practical electrode for discharge surface treatment containing metal hydride in the electrode material could not be obtained. Disclosure of the invention

The present invention has been made in order to solve the above-mentioned problems, and a practical electrode for discharge surface treatment, which can improve the treatment efficiency of the discharge surface treatment, is excellent in safety, and can reduce the production cost, and The purpose is to obtain a manufacturing method.

The discharge surface treatment electrode according to the first invention is a discharge surface treatment used for discharge surface treatment for generating a discharge between the electrode and the material to be treated and forming a hard coating on the surface of the material to be treated by the energy. The electrode for use is formed by mixing at least a powder of a metal carbide and a powder of a metal hydride, performing a heat treatment after compression molding, and releasing hydrogen in the metal hydride.

In the electrode for discharge surface treatment according to a second invention, in the first invention, the metal carbide is titanium carbide, and the metal hydride is titanium hydride.

In the electrode for discharge surface treatment according to a third aspect, in the first aspect, a mixing ratio of the metal carbide powder and the metal hydride powder is set in accordance with an intended electrode strength and susceptibility to collapse. Is what you do.

According to a fourth aspect of the present invention, there is provided a method for producing an electrode for discharge surface treatment, comprising: generating a discharge between the electrode and a material to be treated; and using the energy to form a hard coating on the surface of the material to be treated. Of electrodes for surface treatment of electric discharge used In the method, at least a powder of a metal carbide and a powder of a metal hydride are mixed, heat treatment is performed after compression molding, and hydrogen in the metal hydride is released to produce the electrode for discharge surface treatment. is there.

A method for producing an electrode for discharge surface treatment according to a fifth invention is the method according to the fourth invention, wherein the metal carbide is titanium carbide, and the metal hydride is titanium hydride.

According to a sixth aspect of the present invention, in the method for producing an electrode for discharge surface treatment according to the fourth aspect, the mixing ratio of the powder of the metal carbide and the powder of the metal hydride is adjusted to a desired electrode strength and susceptibility to collapse. It is set in accordance with this.

Since the present invention is configured as described above, it has the following effects.

The discharge surface treatment electrodes according to the first invention and the second invention have an effect of being inexpensive and excellent in safety. In addition, in the discharge surface treatment using the discharge surface treatment electrode, there is an effect that a good hard film can be formed on the material to be treated and the treatment efficiency can be improved.

The electrode for discharge surface treatment according to the third invention has the same effects as the first invention, and the electrode for discharge surface treatment having the strength and collapse of the electrode suitable for the intended discharge surface treatment characteristics is provided. Thus, in the discharge surface treatment using the electrode for discharge surface treatment, there is an effect that a good hard film can be formed according to the characteristics of the material to be treated.

The method for manufacturing an electrode for discharge surface treatment according to the fourth and fifth inventions has an effect that an electrode for discharge surface treatment that is inexpensive and excellent in safety can be stably supplied. Further, in the discharge surface treatment using the electrode for discharge surface treatment manufactured by this manufacturing method, there is an effect that a good hard coating can be formed on the material to be processed and the processing efficiency can be improved. The method for producing an electrode for discharge surface treatment according to the sixth invention is the same as that of the fourth invention. It is possible to manufacture an electrode for discharge surface treatment that has the same effect, and has the strength and fragility of the electrode suitable for the intended discharge surface treatment characteristics. In the surface treatment, there is an effect that a good hard film can be formed according to the characteristics of the material to be treated. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an explanatory view showing an electrode for discharge surface treatment according to the present invention and a method for producing the same.

FIG. 2 is an explanatory diagram showing a configuration example of a discharge surface treatment apparatus using the discharge surface treatment electrode according to the present invention.

FIG. 3 is an explanatory diagram showing a configuration example of a conventional discharge surface treatment apparatus using a discharge surface treatment electrode. BEST MODE FOR CARRYING OUT THE INVENTION

As shown in the background art, a discharge surface treatment electrode is required to have appropriate strength and fragility, and metal hydride, which is a material having such characteristics, has a problem in safety. Therefore, it is necessary to manufacture an electrode made of a material having the same strength and susceptibility as a metal hydride for a discharge surface treatment electrode, and having no problem in terms of safety. For this purpose, experiments conducted on various materials have shown that the strength of a compact electrode formed by compressing powder has a close relationship with the hardness of the powder. In other words, when the powder has a high hardness, for example, when it is a metal carbide or the like, the shape of the powder is not easily changed even by compression molding. is there. When the powder has a low hardness, for example, a powder of a simple metal, the powder is easily deformed by compression molding, and thus has a property of hardening strongly. Therefore, it was found that by mixing powders having different hardnesses at a predetermined mixing ratio and compression molding, an electrode for discharge surface treatment having an intended strength and susceptibility to collapse can be obtained.

Next, as an example, an electrode is manufactured by mixing TiC powder, which is a metal carbide (high hardness) and Ti powder, which is a simple metal (low hardness), as powders having different hardnesses, and compression molding. Will be described. For the electrode for discharge surface treatment, the particle size of the electrode material powder must be about 10 im or less in order to improve the discharge characteristics in the discharge surface treatment, but a material having a sticky Ti Therefore, it is difficult to reduce the particle size of the Ti powder. That is, in order to pulverize the powder, a device called a ball mill is usually used in which the powder and ceramic balls are put into a cylindrical container and rotated. In this case, the powder is deformed because Ti is a sticky material, but the fineness of the powder does not progress very much. Therefore, when the electrode material is Ti powder, a very high manufacturing cost is required to reduce the particle size of the electrode material powder suitable for the electrode for discharge surface treatment. I can't get it.

From the above, it is practical to mix powders having different hardnesses at a predetermined mixing ratio in order to impart the desired strength and susceptibility to collapse to the electrode for discharge surface treatment, and to reduce the particle size of these powders practically. It is important to select electrode materials that can be manufactured at low manufacturing costs. FIG. 1 shows an explanatory view of an electrode for discharge surface treatment according to the present invention and a method for manufacturing the same using an electrode material selected from such a viewpoint. In FIG, 1 0 the electrode for electrical-discharge surface treatment according to the present invention, T i C powder 1 1 is a metal carbide powder, T i H ₂ powder is 1 2 metal hydride Powder, 1 3 metal alone It is Ti powder which is a powder. FIG. 2 shows a configuration using the electrode for discharge surface treatment according to the present invention. In the figure, 2 is a material to be treated, 3 is a processing tank, 4 is a working fluid, 5 is a switching element for switching the voltage and current applied between the electrodes, and 6 is a switching element. 5 is a control circuit for controlling ON / OFF, 7 is a power supply, 8 is a resistor, 10 is a discharge surface treatment electrode according to the present invention, and 14 is a hard coating formed on the material 2 to be treated. . With such a configuration, a discharge is generated between the discharge surface treatment electrode 10 and the material to be treated 2, so that a hard coating having a strong adhesion to the surface of the material to be treated 2 by the discharge energy 14 can be formed.

In (a) of FIG. 1, T i C powder 11 is a material having high hardness, and T i H 2 powder 12 is a material having low hardness. As described above, the strength and fragility of the electrode can be adjusted by the mixing ratio of these powders. According to experiments, compression molding is possible when the mixing ratio of TiC powder 11 and TiH2 powder 12 is in the range of about 1: 9 to 9: 1, and the mixing ratio of TiH2 powder 12 is possible. It is known that the strength of the green compact increases with the increase of the pressure. Therefore, by changing the mixing ratio between the metal carbide powder and the metal hydride powder, it is possible to change the strength of the green compact and, consequently, to change the electrode strength and the fragility.

The compression molding can be performed by placing the mixed powder as the electrode material in a mold and applying pressure by pressing or the like.

As described above, by forming a green compact by using the TiC powder 11 which is a metal carbide powder and the TiH2 powder 12 which is a metal hydride powder, the particle size is reduced (from lm to 3 im or less). ). This is because T i C can easily produce a fine powder industrially, and T i H ₂ can be ground very easily. For example, a mixture of TiC powder having a small particle size and TiH2 powder having a large particle size is subjected to a pulverizing treatment by the above-mentioned ball mill. Particle size , A mixed powder of T i C and T i H 2 having a small particle size can be obtained. In this way, a powder having a small particle size can be easily formed, so that the powder production cost can be reduced.

However, in this state, the strength is low and it is easily broken for use as an electrode for discharge surface treatment. There is also a danger of spontaneous ignition due to the inclusion of titanium hydride. Therefore, the TiC powder and the TiH2 powder are mixed at a predetermined mixing ratio, and the green compact ((a) in FIG. 1) formed by compression molding is subjected to heat treatment to decompose the TiH2. By releasing hydrogen to form the metal T i, it is possible to obtain a practical discharge surface treatment electrode 10 ((b) in FIG. 1) having appropriate strength, fragility, and safety. it can.

The heat treatment can be performed by, for example, high-frequency heating the green compact of FIG. 1 (a) in an electric furnace.

According to such a manufacturing method, it is possible to improve the treatment efficiency of the discharge surface treatment, to provide excellent safety, and to stably supply an inexpensive electrode for discharge surface treatment.

In the above description, the case where T i C powder is used as the metal carbide powder and T i H 2 powder is used as the metal hydride powder, but other metal carbide powder and metal hydride powder may be used. A similar effect is achieved. Industrial applicability

As described above, the electrode for electrical-discharge surface treatment according to the present invention is suitable for use in electrical-discharge surface treatment work. Further, the method for producing an electrode for discharge surface treatment according to the present invention is suitable for producing the electrode for discharge surface treatment.

Claims

The scope of the claims

1. An electric discharge is generated between the electrode and the material to be treated, and the energy of the electric discharge is used to form a hard coating on the surface of the material to be treated.

An electrode for discharge surface treatment formed by mixing at least a powder of a metal carbide and a powder of a metal hydride, performing heat treatment after compression molding, and releasing hydrogen in the metal hydride.

2. The discharge surface treatment according to claim 1, wherein the metal carbide is titanium carbide, and the metal hydride is titanium hydride.

3. The discharge surface treatment method according to claim 1, wherein a mixing ratio of the metal carbide powder and the metal hydride powder is set in accordance with an intended electrode strength and susceptibility to collapse. electrode.

4. In the method for producing an electrode for discharge surface treatment used in a discharge surface treatment for forming a hard film on the surface of the material to be treated by generating a discharge between the electrode and the material to be treated,

A discharge characterized by mixing at least a metal carbide powder and a metal hydride powder, performing heat treatment after compression molding, and releasing the hydrogen in the metal hydride to produce the discharge surface treatment electrode. Manufacturing method of surface treatment electrode.

5. The method for producing an electrode for discharge surface treatment according to claim 4, wherein the metal carbide is titanium carbide, and the metal hydride is titanium hydride.

6. In Claim 4, the mixing ratio of the metal carbide powder and the metal hydride powder is set in accordance with the desired electrode strength and susceptibility to collapse. A method for producing an electrode for discharge surface treatment.