JPS62203720A - Electric discharge machining method for conductive sialon - Google Patents

Abstract

PURPOSE:To promote the high efficiency of machining, by using a brass made wire and setting a specific machining condition, in case of the electric discharge machining for conductive sialon. CONSTITUTION:Wire cut electric discharge machining is performed by using a wire made of brass and setting a discharge current pulse time width to 1.0mus or less, shock coefficient to 6% or less and machining fluid conductivity to about 2mA. In this way, stable and high efficient machining can be performed by setting the electric discharge machining condition, and surface roughness can be decreased small by performing the second cut or the third cut and the like, further a machining alteration layer or a crack can be decreased to a small depth.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a ceramic that has high temperature strength characteristics, corrosion resistance,
The present invention relates to an electric discharge machining method for sialon, which is attracting attention as an alternative material for structural parts made of conventional metal materials due to concerns about its wear resistance.

[Conventional technology]

Ceramics are generally hard, brittle, and difficult-to-process materials, so grinding with a diamond tool is used as the processing method. However, diamond tools wear quickly, high-rigidity processing 1 must be used, and processing is limited to straight-line cutting, surface grinding, or cylindrical processing, so irregular-shaped cutting or deep hole processing is difficult. Therefore, it is a big issue whether it can be applied to products with complex shapes.0 Based on this background, we are aiming to make it possible to process complex shapes and improve machining efficiency by applying the electrical discharge machining method. Conductive ceramics have been developed for this purpose, and research has been conducted on processing techniques, but no specific processing method has been established.

[Problem that the invention seeks to solve]

Regarding electric discharge machining of conductive sialon, which was developed for this purpose, an optimal machining method has not been established, and it has been insufficient in terms of machining complex shapes or improving machining efficiency, which is the original main purpose.

In addition to the development of conductive ceramics, the ceramics industry, universities, and research institutes are also conducting research on their electrical discharge machinability.
Research results regarding in, ZrB2 composite sintered body, 5iaNa-TiC, etc. have been reported. However, the electric discharge machining characteristics of these material systems are not the same due to differences in electrical resistivity, composition, and other characteristics. Furthermore, there have been only a few reports regarding the wire-cut electric discharge machining characteristics of Zr1j2 composite sintered bodies.

In order to be applied as a substitute material for structural parts made of conventional metal materials, it must be possible to perform stable machining without causing wire breakage during machining, and to obtain machining speeds equal to or higher than those of steel or carbide. is required.

FIG. 5 shows the relationship between plate thickness and machining speed when performing myt machining in the negative direction. In the case of steel, the machining speed reaches its maximum when the plate thickness is around 500, and when the wire diameter is 0.2 to σ, the maximum machining speed is about 10 mo/win when the plate thickness is IQlfi (/,).
When plate thickness is 4QIn, approximately 1501i+5/win, plate thickness is 7
At 0, it is about 14,011 m57 north. Even in electrical discharge machining of conductive sialon, is the machining speed equivalent to or higher than that of steel? The goal is to obtain.

An object of the present invention is to provide a wire-cut electric discharge machining method that allows easy machining of complex shapes and highly efficient machining by setting optimal machining conditions for electric discharge machining of conductive sialon.

〔problem? Means to solve the problem]

Generally, in steel or carbide wire cut electric discharge machining, wire Y negative (negative electrode, workpiece positive electrode)
Although it is processed as a pole, the wire polarity is a general cathode even in the case of conductive sialon.

Normally, when performing mv processing, the conductivity of the processing fluid is 10 to 12 m.
A range is used where the impact coefficient (hereinafter referred to as duty factor) is 10% or more. When machining carbide, do you need a conductive layer for machining fluid? The current is approximately 2 mA, and the duty factor is 10% or more, similar to steel.

In the case of conductive steel, if a duty factor of 10% or more is used, such as steel or carbide, the discharge state will become unstable, the wire will break more frequently, and stable machining will not be possible. Therefore, it is desirable to use a region with a duty factor smaller than 10%. Also, the electrical conductivity of the machining fluid is 2mA, which is the same as in carbide machining.
It is better to obtain sufficient discharge energy and perform stable machining.

The present invention achieves a machining speed equivalent to or higher than that of steel or carbide by setting the discharge IE current pulse time width (hereinafter referred to as discharge pulse width) to a range of 1.0 μs or less under the above conditions. This enables stable machining with almost no wire breakage.

〔Example〕

Hereinafter, the present invention will be explained based on examples.

The composition and manufacturing method of the conductive sialon in Examples are as shown below, and the warpage properties are shown in Table 1.

Composition: 90%5ialia+7Y*Os+3Atli
t: Retype-+5AAaOn.

For the above SiAlON composition blend, 40 vot% TΔ addition Molding: After ball mill mixing, rubber press molding and sintering: N,
Sintering under normal pressure in an atmosphere Table 1 Next, the processing conditions of this example are as shown in Table 2.

Table 2 The wire material used was brass, which is commonly used, and the wire diameter was 0.2111. The wire is guided by a diamond die above and below the workpiece, and appropriate tension is applied to the wire, and the processing liquid is applied to the wire from above and below the workpiece. This is a general machining method that performs machining while blowing.

The discharge conditions shown in Table 2 were selected based on the warping conditions after finding the conditions that would allow stable machining and maximize the machining speed for each plate thickness.

The machining results in Examples will be explained below. In Fig. 1, the maximum machining speed that allows relatively stable machining is 160 - when expressed in cutting area per unit time.
A processing speed of 200 m5/min was obtained, which is faster than steel at any plate thickness.

In FIG. 2, the machining speed increases as the discharge pulse width increases, but in the region where the discharge pulse width is 12 μs or more, wire breakage is likely to occur, so the discharge pulse width is set to 1.
A region of 2 μs or less was used.

In Fig. 3, the machining speed tends to increase as the duty factor increases, but even if the duty factor is increased by changing the pause time, the change in machining speed σ will be less when the discharge pulse width is increased. Therefore, the discharge pulse width has a greater influence on the machining speed.

In order to perform highly efficient and stable machining, the discharge pulse width must be 1.0μs or less, the duty factor must be 10% or less,
Moreover, as shown in FIG. 3, it is desirable to use a small area of 6% or less and to reduce the machining fluid tolerance to about 2 m people.

From the above results, the wire cut electric discharge machining method of the present invention has a discharge pulse width of 1.0 μs or less and a duty factor of 76% or less. In Figure 4, the heading page was created.
Even if the discharge pulse width is changed, there is almost no effect on the surface roughness. Here, the thicker the plate, the greater the surface roughness, but this is due to the fact that the thicker the plate, the higher the machining voltage and the greater the discharge energy 2 in order to increase the machining speed. It is. In the case of wire cut electrical discharge machining, is there generally a 2nd cut or a 3rd force cut? In this example, the discharge pulse width is 1.0 μs or less, and the due knife actor is 6% or less, and 2nd cut or 3rd cut is used.
By performing rd cutting or the like, the surface roughness can be reduced and the depth of the process-affected layer or cracks can be reduced.

Note that if the diameter of the wire to be used is different from this example, the current value is selected according to the diameter of the warp wire.

〔Effect of the invention〕

The present invention described above has the following effects.

B. Set discharge conditions within the range of discharge hull width 1.0 μs or less, duty factor 6% or less, and machining fluid conductivity 4.
By setting the current to about 2 mA, stable and highly efficient machining can be achieved.

Mouth: Is it possible to use a general wire-cut electrical discharge machine by processing using the above processing conditions? Conductive sialon can be processed with high efficiency without changing the wire polarity.

C. Due to the above effects, as shown in Table 3, it is possible to process at a speed equal to or higher than that of steel or carbide.

[Brief explanation of drawings]

Figure 1 shows the relationship between plate thickness and maximum machining speed. Figure 2 shows the relationship between discharge pulse width and machining speed. Figure 3 shows the relationship between duty factor and machining speed. Figure 4 shows the relationship between duty factor and machining speed. Figure 5 shows the relationship between discharge pulse width and surface roughness, and Figure 5 shows plate thickness and machining in W4 machining. It is a figure showing relationship 2 of speed. Engraving of the drawings (no changes to the contents) Fig. 7 Fig. 2 No. 1 dimension, isn 3 Fig. 4 × Pulse width 0ts) Plate thickness (a) Procedural amendment, zero) G1. 6.20 Indication of the case 1986 Patent Application No. 45657 Name of the invention Relationship with the Person Who Amended the Electrical Discharge Machining Method for Conductive Sialon Case Patent Applicant Address 2-1 Marunouchi, Chiyoda-ku, Tokyo Contents of the specification and drawing amendments subject to amendment No. 2

Claims (1)

[Claims] A method for wire-cut electric discharge machining of conductive sialon, characterized in that a brass wire is used in the wire-cut electric discharge machining of conductive sialon, and the machining is performed within a discharge current pulse time width of 10 μs or less and an impact coefficient of 6% or less.