JP3053944B2 - EDM electrode for forming annular groove - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk-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 machining method for forming an annular groove by electric discharge machining, which is an object of the present invention, will be described. FIG.
As shown in FIG. 3, a disk-shaped machining electrode 1 and a cylindrical workpiece 2 such as a grinding wheel are arranged close to each other while keeping their central axes P and Q parallel (in a machining fluid).
Then, the work 2 is brought close to the work 2 while being rotated about the respective central axes P and Q, the machining electrode 1 and the work 2 are connected to a machining power source, and an annular groove 3 is formed on the outer periphery of the work 2 by electric discharge machining. The disk-shaped machining electrode 1 used for such electric discharge machining is an object of the present invention.

[0003]

As described above, the work 2
The important thing in processing the annular groove 3 on the outer periphery of FIG.
As shown in (A), the width W of the groove 3 is uniform over the entire region in the depth direction, and the corner at the deepest part of the groove 3 and the corner between the groove 3 and the outer periphery of the work are each as perpendicular as possible. . With respect to this target, the present inventors repeated the processing test using the processing electrode 1 (FIG. 1) having a constant thickness and a right outer peripheral corner. As a result, as shown in FIG. 2B, in the annular groove 3 actually machined in the work 2, the groove width W1 on the outer peripheral side thereof becomes considerably larger than the target value W, and the corner and the maximum of the deepest part of the groove are formed. The outer corners are also rounded. Such a defect of the groove shape becomes larger as the processing electrode 1 is consumed by long-term use, but also occurs at a considerable level even in the early stage when the processing electrode 1 is not consumed at all. In the past, we couldn't overcome these problems,
The process of 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.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to form a highly accurate annular groove in the outer periphery of a cylindrical work by using a disk-shaped machining electrode. Is to do so.

[0005]

According to the present invention, in the electric discharge machining electrode for machining an annular groove as described above, the shape of the effective portion of a predetermined area on the outer peripheral side is symmetrical and the thickness thereof is set to the outer peripheral area. Down to the inner circumference.

[0006]

The discharge occurs 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 deeper to some extent, the machining electrode enters the groove. At this time, since the outermost periphery of the machining electrode is the thickest, discharge occurs in a small 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. Unnecessary discharge or electrolytic reaction hardly occurs in this part because of dripping.

[0007]

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. Center shaft 1a
The basic configuration that the disk-shaped machining electrode 1 is integrated concentrically with the conventional one is the same as the conventional one. However, the thickness of the disk-shaped electrode 1 is not constant, the thickness Wa at the outermost portion is the largest, and gradually decreases to the thickness Wb at the inner portion. Moreover, the shape of the disk-shaped machining electrode 1 is symmetrical, so that the front and back surfaces of the machining electrode 1 and the central axis P
Are equal.

FIG. 4 shows a state in which an annular groove 3 is being formed on the outer periphery of a cylindrical workpiece 2 by electric discharge machining using the machining electrode 1 configured as shown in FIG. As shown in the figure, the machining proceeds while the outermost peripheral portion of the disk-shaped machining electrode 1 enters the deepest portion of the annular groove 3 of the work 2, and the thickness of the outermost peripheral portion of the electrode 1 is increased. Since Wa is the largest and the thickness of the electrode 1 decreases toward the inner periphery, 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 Discharge occurs in a minute gap portion from the deepest portion, and machining proceeds. Unnecessary discharge and electrolytic reaction do not occur between the outer peripheral portion of the groove 3 and the electrode 1, so that a defect that the groove width is widened or rounded is less likely to occur.

[0009]

As described in detail above, by using the disk-shaped machining electrode according to the present invention having a gradually decreasing thickness from the outer periphery to the inner periphery and having a symmetrical shape on the front and back, a cylindrical shape is obtained. When forming an annular groove on the outer periphery of the workpiece by electric discharge machining, the groove width of the annular groove to be machined becomes substantially uniform in the depth direction, and the corner portion of the deepest portion of the groove 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 the drawings]

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

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

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 showing a state in which an annular groove is being machined by the electric discharge machining electrode of FIG. 3;

[Explanation of symbols]

 1 machining electrode 2 work 3 annular groove

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-127625 (JP, A) JP-A-2-250726 (JP, A) JP-A-3-264214 (JP, A) JP-A 57-127 132925 (JP, A) Hikaru 2-43164 (JP, U)

Claims (1)

(57) [Claims] 1. A disk-shaped machining electrode and a cylindrical workpiece are arranged close to each other while keeping their central axes parallel.
A disk-shaped machining electrode used to form an annular groove on the outer periphery of a workpiece by electric discharge machining while rotating the machining electrode and the work around their respective central axes as rotation centers, and the effective area of a predetermined area on the outer periphery is used. The shape of the part is symmetrical,
An electric discharge machining electrode for forming an annular groove, wherein the thickness of the electric discharge machining electrode gradually decreases from the outer periphery to the inner periphery.