JPH05185323A - Discharge processing electrode for forming ring groove - Google Patents

Abstract

PURPOSE:To provide a ring groove having an acute angle at each corner by embodying it so that the thickness lessens gradually from the periphery toward the internal circumference and that the shape is symmetrical to the front and rear, and thereby generating approx. uniform width in the direction over the depth. CONSTITUTION:Processing proceeds in such a condition that the outermost part of a dics-form processing electrode 1 has intruded to the deepest part in a ring groove 3 formed in a work 2. Therein the thickness of the electrode 1 Wa is largest at the outermost part to decrease toward the internal circumference, and the shape is symmetrical to the front and rear. Therefore, the gap between the periphery of the groove 3 and the electrode 1 is kept comparatively large, and electric discharge takes place in a micro-gap part between the outermost of the electrode 1 and the groove 3, and the processing proceeds. No discharge or electrolytic reaction which is unnecessary, does not occur between the periphery of the groove and the electrode 1, which reduces likelihood of generation of poor workmanship such as widening or rounding of the groove.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc-shaped electric discharge machining electrode used for forming an annular groove on the outer periphery of a cylindrical work by electric discharge machining.

[0002]

2. Description of the Related Art First, a method of forming an annular groove by electric discharge machining, which is the object of the present invention, will be described. Figure 1
As shown in FIG. 1, the disk-shaped machining electrode 1 and the cylindrical work 2 such as a grindstone for grinding are closely arranged while keeping their central axes P and Q parallel to each other (in the machining liquid).
Then, the workpiece 2 is brought closer while rotating about the respective central axes P and Q, the machining electrode 1 and the workpiece 2 are connected to a machining power source, and the annular groove 3 is formed on the outer periphery of the workpiece 2 by electric discharge machining. The disk-shaped machining electrode 1 used for such electric discharge machining is the subject of the present invention.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
2 is important for processing the annular groove 3 on the outer periphery of
As shown in (A), the width W of the groove 3 is uniform over the entire area in the depth direction, and the corners of the deepest part of the groove 3 and the corners of the groove 3 and the outer circumference of the work are as perpendicular as possible. .. With respect to this target, the present inventors repeated the machining test using the machining electrode 1 (FIG. 1) whose thickness is constant and the outer peripheral corners are right angles. As a result, as shown in FIG. 2 (B), in the annular groove 3 that is actually machined in the work 2, the groove width W1 on the outer peripheral side becomes considerably larger than the target value W, and the corners and the maximum depth of the groove are increased. The outer corners are also rounded. Such a defective groove shape increases as the machining electrode 1 wears down due to long-term use, but occurs at a considerable level even in the early stage when the machining electrode 1 is not worn at all. In the past it was not possible to overcome such problems,
The machining for forming the annular groove 3 in the work 2 such as a cylindrical grindstone with high precision has been performed by a method other than wire cut electric discharge machining or electric discharge machining.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to make it possible to form an annular groove with a high groove shape on the outer circumference of a cylindrical work by means of a disk-shaped working electrode. To do so.

[0005]

Therefore, in the present invention, in the electric discharge machining electrode for machining the annular groove as described above, the shape of the effective portion of the predetermined area on the outer peripheral side is symmetrical to the front and back, and the thickness thereof is the outer peripheral. It became smaller toward the inner circumference.

[0006]

The discharge is generated in the minute gap between the outermost periphery of the disk-shaped machining electrode and the cylindrical work, and the annular groove is gradually formed. When the annular groove becomes deep to some extent, the machining electrode enters the groove. At that time, since the outermost periphery of the machining electrode is thickest, electric discharge occurs in the minute gap between the outermost periphery of the electrode and the workpiece, but the gap between the outermost periphery of the machined annular groove and the machining electrode is kept large. Since it sags, unnecessary discharge or electrolytic reaction hardly occurs in this part.

[0007]

EXAMPLE FIG. 3 shows a specific example of the shape of the electric discharge machining electrode 1 for forming an annular groove according to the present invention. Central shaft 1a
The basic configuration in which the disk-shaped machining electrode 1 is integrated concentrically with is the same as the conventional one. However, the thickness of the disk-shaped machining electrode 1 is not constant, the thickness Wa of the outermost peripheral portion is the largest, and gradually decreases to the thickness dimension Wb of the inner periphery. Moreover, the shape of the disk-shaped machining electrode 1 is symmetrical on the front and back sides, and therefore the front and back surfaces of the machining electrode 1 and the central axis P are formed.
The angles θ formed by are equal.

FIG. 4 shows a state in which an annular groove 3 is being formed by electrical discharge machining on the outer periphery of a cylindrical work 2 using the machining electrode 1 constructed as shown in FIG. As shown in the figure, the machining proceeds with the outermost peripheral portion of the disk-shaped machining electrode 1 entering the deepest portion of the annular groove 3 of the work 2, but the thickness of the outermost peripheral portion of the electrode 1 Since Wa is the largest and the thickness of the electrode 1 becomes smaller toward the inner circumference, the gap between the outer peripheral portion of the groove 3 and the electrode 1 is kept relatively large, and the outermost peripheral portion of the electrode 1 and the groove 3 are kept. Electric discharge occurs in the minute gap portion with the deepest portion, and the processing proceeds. Unnecessary discharge or electrolytic reaction does not occur between the outer peripheral portion of the groove 3 and the electrode 1, and therefore, defects such as widening or rounding of the groove are less likely to occur.

[0009]

As described in detail above, by using the disk-shaped machining electrode according to the present invention, the thickness of which gradually decreases from the outer circumference to the inner circumference and which has a symmetrical shape on the front and back sides, When forming an annular groove by electric discharge machining on the outer periphery of the work, the groove width of the annular groove to be processed is almost uniform in the depth direction, and the corner portion of the deepest groove portion and the corner portion of the outermost peripheral portion are not greatly rounded, An annular groove having a constant groove width and an acute angle can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing an electric discharge machining method for an annular groove, which is a target of the present invention.

FIG. 2 is a diagram showing an ideal state and a conventional actual state of a groove shape processed by the same method.

FIG. 3 is a configuration diagram of an electric discharge machining electrode according to an embodiment of the present invention.

FIG. 4 is an explanatory view in the middle of processing an annular groove by the electric discharge machining electrode of FIG.

[Explanation of symbols]

 1 Processing electrode 2 Work piece 3 Annular groove

Claims (1)

[Claims] 1. A disk-shaped machining electrode and a cylindrical work are closely arranged with their respective central axes kept parallel,
A disk-shaped machining electrode used to form an annular groove on the outer circumference of a workpiece by electrical discharge machining by rotating the machining electrode and the workpiece closer to each other while rotating them about their respective center axes. The shape of the part is symmetrical on the front and back,
An electric discharge machining electrode for forming an annular groove, characterized in that its thickness gradually decreases from the outer circumference to the inner circumference.