JPS58126003A - Diamond tool and manufacture thereof - Google Patents

Abstract

PURPOSE:To accurately and efficiently machine a material into a specified form by electrospark machining by using an artificial diamond grain having conductivity. CONSTITUTION:A conductive diamond having resistance below 10<3>OMEGA.cm is usable. A machining tool is obtained by bonding one or a plurality of said diamond (s) 1 to a conductive holder 3, using a conductive bonding material 2. Using an electrospark machine on the market, for instance, voltage is applied to the diamond itself of said tool and an electrode of the electrospark machine. A material is machined into a specified form by spark erosion of diamond which is produced by transient arc discharge, which occurs repeatedly between the electrode and the surface of a diamond.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a diamond tool that can accurately and efficiently machine a predetermined shape by electrical discharge machining using synthetic diamond grains having electrical conductivity. It is something.

Diamond tools are broadly classified depending on the size of the diamond used. Generally, there are tools that use large single crystals called diamond grains (Polar) and tools that use fine diamond powder (powder).Polar is generally about 1/180 carat or more and about 0.7JL in diameter.
This product uses naturally occurring rough stones of more than 100,000 ml.

Powders, on the other hand, include crushed natural stones and artificially synthesized powders. In recent years, diamond synthesis technology under ultra-high pressure and high temperature has progressed, and most of the industrially used powder with a diameter of 0.7 B or less has been replaced with synthetic diamond. However, it is difficult to industrially synthesize large single-crystal diamonds with a size of 0.7 B or more, and although success has been achieved in the laboratory, industrialization has not yet been achieved.

The inventors worked on developing an industrial synthesis technology for Diamondports, which had previously been made only from natural rough stones, and published their earlier application (Japanese Patent Application No. 54-141918.54-153186,
55-2818. 55-26651.55-444
29), and obtained prospects for industrialization. The present invention was first made possible by this large single crystal synthesis technology.

Diamond has the highest hardness of all existing materials. Also, most of them are electrical insulators with a resistivity of 1Q16Ω/flaw. 1040 is extremely rare among natural gemstones.
It is known that semiconductor diamonds exist that have a resistivity of less than m. However, since the production amount is extremely small, there seems to be no example of its application for industrial purposes, especially for diamond tools.

As mentioned above, diamond is a substance with the highest hardness, and diamond tools are used in a wide variety of applications, such as cutting tools for machining, dressers, wire drawing dies, and drilling bits. Some tools that use bones, such as Surf Ace set bits and some dressers, are used only to join the rough stone to a support such as steel, but diamond bits, dies, and most dressers use bones. , a glass cutter, etc. are used by fixing one or more diamond grains to a support and molding them to give them a predetermined shape.

Currently, the main methods for processing diamonds are polishing them using diamond powder or grinding them using a diamond grindstone. diamond·
Since there is no substance with higher hardness, it is impossible to process using a tool material with higher hardness, as in the case of machining ordinary materials. Diamond-on-diamond processing is extremely inefficient and takes a long time. For this reason, in recent years, for example, laser processing has been applied to the drilling of diamond dies, and the processing time has been greatly shortened. However, although laser processing is effective for drilling holes with a certain diameter or more, it is difficult to process micro holes with a diameter of 0.1B or less, and it is difficult to process holes with a certain predetermined curved surface. Not applicable.

The purpose of the present invention is to dramatically improve the efficiency of all diamond tool processing methods by changing the characteristics of diamond itself, and to make it possible to create shapes that were previously difficult to process. be.

The diamond used in the present invention is a conductive diamond with a resistivity of 10 8 Ω·m or less. One or more of these diamonds are bonded to a conductive support using a conductive bonding material to form a tool.

For example, using a commercially available electric discharge machine, a voltage is applied between the diamond itself and an electrode to repeatedly generate a transient arc discharge on the surface of the electrode and the diamond, which causes spark erosion of the diamond to be machined into a predetermined shape. be.

The diamond used in the present invention is obtained by incorporating boron during synthesis. Boron is one of the additives that determines the conductivity of diamond, but the exact relationship between the amount added and resistivity is currently not well understood.

Experiments have shown that synthetic diamond with a resistivity of less than 101' Ω·m contains at least 1 ppm of boron.

The upper limit of resistivity was determined by actually performing electrical discharge machining. Diamond, which exhibits a resistivity exceeding 10' ohms, cannot be electrically discharged at a substantial speed.

According to the present invention, by making diamond itself conductive, electrical discharge machining becomes possible, and machining efficiency can be dramatically improved compared to conventional mechanical machining methods that rely on polishing. Furthermore, tools that cannot be produced using conventional methods, such as tools with complex shapes or concave curved surfaces, can be easily obtained.

Example 1 A foamed dresser was manufactured using a synthetic diamond single crystal of Colorad with a diameter of about 5 mm.

This diamond was synthesized using ultra-high pressure and high temperature equipment, contains approximately 5 atomic ppm of boron, and has a resistivity of approximately 10 jΩ·mm. Cut this single crystal
It was fixed to a steel support with a hod brace using a mixed powder binder of APt Fe. A formed dresser having a concave curved surface as shown in FIG. 1 was machined using a wire-cut electrical discharge machine.

Conventionally, it has been difficult to manufacture a diamond weight dresser with such a shape.

Example 2 A diamond cutting tool was manufactured using a synthetic diamond single crystal with a diameter of about 6 mm and a resistivity of about 800 mm. The shape of the cutting edge is shown in Figure 2. The diamond was fixed to the steel shank in the same manner as in Example 1, and the cutting edge was formed by electric discharge machining using a kp-W electrode having a shape matching the cutting edge R. Conventional cutting edge polishing and shaping using diamond powder took about 50 hours, but the cutting tool of the present invention could be processed in 5 hours.

[Brief explanation of drawings]

FIG. 1 shows one application example of the present invention, which is a weight-formed dresser having a concave curved surface, and FIG. 2 shows another example, which is a diamond cutting tool. In each figure, numeral 1 is a conductive diamond that has been electrically discharge-machined into a predetermined shape. 2 is a conductive bonding material for fixing the diamond to a support, and 8 is a support such as steel.

Claims (3)

[Claims] (1) One or more conductive diamond single crystals with a resistivity of 1080·a or less are fixed to a conductive support using a conductive bonding material, and the diamond single crystal is formed by electrical discharge machining. A diamond tool characterized by being processed into a predetermined shape. (2) The diamond tool according to claim (1), which uses an artificially synthesized diamond single crystal containing 1 atomic ppm or more of boron and having a resistivity of 1080·1 or less. (3) A diamond single crystal with a resistivity of 1080·1 or less is bonded and fixed to a conductive support using a conductive bonding material, and a transient arc discharge is repeatedly generated between the electrode and the diamond single crystal. A method for manufacturing a diamond tool having a predetermined shape, which comprises machining and removing the surface of a single crystal.