JPS59152020A - Grind wheel used for electrolytic and electric discharge machining - Google Patents

Abstract

PURPOSE:To increase efficiency of electrolytic and electric discharge machining by constructing a grind wheel so as to carry out electrolytic operation, mechanical grinding operation, and electric discharge operation. CONSTITUTION:On the circumferential surface of a non-conductive grind wheel A, a conductive zones B constructed by conductive material and grinding zones C, in which non-conductive grains are being exposed, are formed alternately. Current collecting plates D are installed on the sides of the grind wheel A being formed in such a way that each conductive plate can be electrically connected to them. Electrolytic operation is carried out with a workpiece M being brought in contact with the conductive zones B of the grind wheel A. Then, oxydizing film is removed by means of grinding zones C. And electric discharge machining is carried out with the workpiece M being momentarily brought in contact with the conductive zone B.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a disc grindstone for electrolytic discharge grinding.

When machining difficult-to-cut materials such as cemented carbide, conventional machining methods using mechanical grinding have low machining capabilities and are difficult to process.

Therefore, the inventor of the present invention proposed an electrolytic discharge machining method that uses a special grindstone and has high machining efficiency.

The electrolytic discharge machining will be briefly explained below.

<A> Structure of the grindstone In Figure 6, (A) is a non-conductive grindstone, and the circumferential surface of this grindstone (A) is equipped with a conductive band (made of a conductive material).
B) and the polishing band (0) with the non-conductive abrasive grains exposed as they are.
are formed alternately.

Further, a current collector plate (D) is arranged on the side surface of the grindstone (A) so that each conductive plate (B) is electrically connected.

Machining method Electricity is applied between the conductive band (B) of this grindstone and the workpiece (M) to supply machining fluid and rotate the grindstone.

Then, the workpiece (M) has a conductive band (B) and an abrasive band (0).
It has been found that because of the alternating contact between the two, an electric discharge action is performed in addition to the electrolytic action and the mechanical polishing action, and it has been found that difficult-to-cut materials can be efficiently ground.

The mechanism of each action is considered as follows.

(Row 1) Electrolytic action At the moment when the workpiece (M) and the conductive band (B) of the grindstone (A) come into contact, electrolysis occurs on the surface of the workpiece (M). becomes metal ions and begins to dissolve.

(Row 2) Mechanical grinding action Immediately after this, the abrasive band (0) of the grindstone (A) passes, and the abrasive grains scrape off the dissolved portion and oxide film. In this way, the processed surface is always activated because the oxide film and the like are removed immediately after they are generated.

Therefore, electrolysis is possible with a much smaller current than in conventional electrolytic grinding.

(Row 3) Discharge action Different from conventional electrolytic grinding wheels, conductive bands (B) are discontinuously present.

Therefore, one conductive band (B) is only in momentary contact with the workpiece (M). Therefore, during a short period of time between contact and separation, charging and discharging phenomena occur due to the Norse current, and sparks fly between the two.

The spark immediately turns into a thin column of sparks, that is, a flow of electrons with extremely high current density, melting and blowing away one point on the workpiece (M).

Electric discharge machining is performed in this manner.

By the way, with the above-mentioned structure, the circumferential surface of the whetstone (man) remains smooth even if a predetermined machining liquid is supplied between the whetstone (M) and the workpiece (M) during processing. It became difficult for the Loe liquid to enter the machine, and it was not possible to sufficiently supply the machining liquid to the machining part.

This is especially true when the cutting depth of the grindstone (A) increases and the workpiece (
When the contact area with M) becomes large, sufficient supply of machining fluid cannot be expected, and as a result, a decrease in machining efficiency has to be tolerated.

Also, during the electric discharge machining described above, the conductive band (B) of the grinding wheel (A)
and the workpiece (M), a certain distance (discharge gap) is formed between them in order to obtain efficient electrical discharge machining, and it is desirable to maintain this distance. It was difficult to maintain.

The present invention has been made in view of the above points, and an object of the present invention is to provide a disc grindstone for electrolytic discharge grinding as shown below.

<B> Disc grinding wheel for electrolytic discharge grinding that can supply sufficient machining fluid between the workpiece and the workpiece. Disc whetstone.

Next, an example will be described.

<A> Disk main body The disk main body is a disk (1) made of known non-conductive abrasive grains baked and hardened using a suitable non-conductive abrasive.

Examples of abrasive grains that can be used include green carborundum, white alundum, pink alundum, and silica.

The material is non-conductive; the disk (1) has no conductivity.

<Mouth> Creation of grooves A plurality of discontinuous grooves (2) are formed on the side surface of the disk (1), reaching the circumferential edge and having, for example, a U-shaped, V-shaped, or semicircular cross section.

The grooves (2) are formed to a depth slightly exceeding half the thickness of the disk (1), and are formed alternately on both the front and back surfaces of the disk (1).

In other words, the circumferential surface of the disk (1) has grooves (2) on one side and grooves (2) in the middle, and grooves (2) on the other side.
2) will be formed alternately so that they are located.

As a result, each groove (2) has walls (21) facing each other,
A bottom surface (22) is formed that connects both wall surfaces (21).

<...> Formation of conductive band The wall surface (21) and bottom surface (22) in the groove (2) are coated with a conductive film to form a conductive band (3).

To form this film, a known conductive material with low electrical resistance is used, and a thin coating is applied by baking, painting, pasting, or the like.

As a result, a conductive band (3) with a U-shaped cross section is exposed on the circumferential surface of the disk (1), and an abrasive band (4) made of non-conductive abrasive grains is exposed outside the conductive band (3). It is formed by

A donut-shaped conductive current-carrying plate (5) is provided at the center of the side surface of the shoe current-carrying plate disc (1).

Current-carrying plates (5) are provided on both sides of the disc (1) and are electrically connected to each of the conductive bands (2).

Next, the grinding method will be explained.

<1> Formation of energizing circuit The energizing plate (5) of the disk (1) with the above structure and the workpiece (M)
Connect electrodes to each to form a current-carrying circuit.

The power supply that passes between the disc (1) and the workpiece (M) can be either AC, DC, or a combination of AC and DC, depending on the material of the workpiece (M). Use them differently.

<2> Rotate the grinding start disk (1) and bring the disk (1) into contact with the workpiece (M) while supplying a predetermined machining fluid.

When the conductive band (3) formed exposed on the circumferential surface of the disk (1) contacts the workpiece (M) and is energized, both (3)
(M) As mentioned above, a discharge phenomenon occurs and the workpiece (
The surface of M) is melted, and then a polishing band (4) made of non-conductive abrasive grains passes through and scrapes off this melted portion.

Furthermore, when electricity is applied between the conductive band (3) of the disk (1) and the workpiece (M) through a working fluid that also has the characteristics of an electrolyte, ions of the workpiece (M) are caused by electrolysis. Decomposition progresses.

Immediately after this, the polishing band (4) passes through and scrapes off the surface of the ionically decomposed workpiece (M).

Note that the above processing is performed alternately on both the front and back surfaces of the disk (1).

Therefore, each conductive band (3) on both sides of the disk (1) is connected to the disk (1).
Since it is formed to a depth that exceeds about half the thickness of

<3> Maintaining the discharge gap During grinding Each conductive band (3) at the circumferential edge of the disk (1) is connected to the workpiece (M
) and is slightly chipped, forming a gap @(H) between the surface of the workpiece (-M) and the surface of the workpiece (-M).

This interval (H) is maintained at a substantially constant distance because the tip corner of the groove (2) is chipped as the disk (1) wears.

Therefore, this interval (H) becomes a discharge gap which is an optimum discharge interval for performing a good discharge, and the discharge gap is always maintained during grinding.

<4> In the case of closed cutter, the disk (1) and the workpiece (M) undergo electric discharge machining,
Grinding of the workpiece (M) progresses while performing electrolytic machining 2 mechanical grinding processes alternately, but if the depth of cut into the workpiece (M) increases and becomes a deep cut, the disk (1)
The machining fluid is guided to the groove (2) of the conductive band (3) recessed on the side surface of the workpiece (M) and is reliably supplied to the contact area with the workpiece (M), thereby preventing heat generation and grinding caused by insufficient machining fluid. Clogging of the band (4) is prevented, and efficient electrical discharge machining, electrolytic machining, and mechanical machining are performed.

<5> Other Examples In addition to the above embodiments, a conductive band (3) formed in an inclined groove (6) as shown in FIG. 4 may be used as the conductive band that also serves as a supply of machining fluid. .

That is, on the side surface of the disk (1) made of non-conductive abrasive grains, inclined grooves (6) which become deeper as they get closer to the circumferential surface are formed alternately on both sides of the disk (1), reaching the circumferential surface. do.

Next, the inner wall of each inclined groove (6) is coated with a conductive material having excellent conductivity and low resistance to form a conductive band (3).

The grinding method and effects are the same as in the previous embodiment.

Furthermore, in the above embodiment, a conductive band (3) is provided on the circumferential surface of the disk (1).
When forming a groove (2) (
6) As shown in Fig. 5, a transverse groove (7) opened across the circumferential surface is coated with a conductive film to form a conductive band (3). can also be expected to have similar effects.

Since the disc of the present invention is constructed as described above, the following effects can be expected.

<B> By providing a groove on the side surface of the disk that communicates with the circumferential edge, the machining fluid is guided by this groove and guided between it and the workpiece, ensuring a sufficient supply of machining fluid. can be done.

<Mouth> By coating the groove with a conductive film to form a conductive band, the tip corner of the groove is chipped during grinding due to wear of the disk, so there is a gap between the conductive band and the surface of the workpiece. A certain gap is formed.

Therefore, this gap becomes a discharge gap and good grinding can be performed.

[Brief explanation of drawings]

No. 1m: An explanatory diagram of one embodiment of a disc according to the present invention Tube 2 An enlarged partial explanatory diagram of the circumferential surface of the disc. Fig. 3: An explanatory diagram during grinding. Figure 6: Explanation of processing method using special grindstone 1 = Disc 2: Groove 3: Conductive band 4: Abrasive band Figure 2 3 Procedural amendment 1. Indication of the case Japanese Patent Application No. 57-187548 2, Name of the invention Disc grinding wheel used for electrolytic discharge machining 3, Person making the amendment Relationship to the case Patent applicant Address 602 Komaoka-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Name
Applied Magnetic Research Institute Ltd. Representative: Akio Kuromatsu 4, Agent: 105 Address: 9F6 Marufuji Building, 3-1-10 Shinbashi, Minato-ku, Tokyo, Specification subject to amendment 7, Page 1 of the statement of contents of amendment 1. The name of the invention is corrected to "Disc grindstone used for electrolytic discharge machining."

Claims (1)

[Scope of Claims] A grindstone made of non-conductive abrasive grains has grooves extending from the side surface to the circumferential surface at multiple discontinuous locations, and a conductive coating is applied to the grooves to form conductive bands. A disc grindstone used for electrolytic discharge machining, in which the circumferential surface other than the conductive band forms an abrasive band, and each conductive band is configured to conduct electricity.