JPH05277922A - Spherical machining of ring part - Google Patents

Abstract

PURPOSE:To spherically process the outer periphery of a ring part consisting of ceramics and others by using a universal cup grinding wheel at a low cost and highly in precision. CONSTITUTION:A ring part 2 rotates around its axis A. A cup grinding wheel 4 having inner diameter which is larger than thickness of the ring part 2 is rotated around an axis B vertical against the rotation axis A of the ring part 2. By giving a slit along the axis B to the cup grinding wheel 4, the outer periphery of the ring part 2 is spherically ground.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for spherically processing the outer periphery of a ring-shaped component, and more particularly to a spherical surface processing method suitable for a ceramic ring-shaped component.

[0002]

2. Description of the Related Art For example, as a technique for spherically machining the outer periphery of an outer ring in a ball bearing for a rolling bearing unit (JIS B1558), a plunge grinding method using a conventional grindstone having a polishing surface complementary to a finishing surface has been conventionally used. Also, a processing method is known in which the movement path of the flat grindstone is controlled by a copying apparatus or an NC apparatus.

[0003]

However, according to the grinding method using the full-form grindstone, it is necessary to manufacture a large number of dedicated grindstones, which increases the cost of the grindstone. There are problems that the grindstone cannot be used, the grindstone has a shape-deformation, and the processing accuracy decreases, so that the grindstone needs to be corrected or replaced at an early stage, and the surface roughness deteriorates due to plunge grinding. On the other hand, in the case of the machining method by copying or NC control, a general-purpose plain grindstone can be used, which is advantageous in terms of cost, but on the other hand, the local wear of the grindstone is severe and it is difficult to correct the movement trajectory of the grindstone, so that frequent truing or There is a problem that dressing is required, which hinders automation of the polishing process and cost reduction. Particularly in the case of ceramic ring-shaped parts, it was very difficult to maintain the shape of the grindstone by any of the conventional methods.

Therefore, an object of the present invention is to provide a spherical surface processing method for a ring-shaped part which can reduce the cost of the grindstone and improve the processing accuracy. In addition to the ring shape, the shape of the ring-shaped part includes parts such as a cylindrical shape, a columnar shape, and a disc shape.

[0005]

In order to solve the above problems, the spherical surface processing method of the present invention rotates a ring-shaped part around its axis and has an inner diameter larger than the thickness of the ring-shaped part. It is characterized in that the cup grindstone is rotated around an axis perpendicular to the rotation axis of the ring-shaped component to give a cut to the cup grindstone to polish the outer periphery of the ring-shaped component into a spherical surface.

[0006]

According to the spherical surface processing method of the present invention, since the cup grindstone having the inner diameter larger than the thickness of the ring-shaped component is used, the inner circumference of the cup grindstone makes line contact with the outer periphery of the ring-shaped component, and in this state. When the cup grindstone rotates, a spherical surface having a radius of curvature larger than the inner diameter of the cup grindstone is continuously formed on the outer circumference of the ring-shaped component. In this case, since the relationship between the outer diameter D of the ring-shaped component and the radius of curvature R of the spherical surface is D = 2R, changing the cutting amount of the cup grindstone changes the outer diameter dimension of the ring-shaped component, and accordingly The radius of curvature of the finished surface also changes. Therefore, the finished surface can be processed with different sizes by one cup grindstone, the versatility of the grindstone is increased, and the grindstone cost can be significantly reduced. Also, since the cup grindstone is rotated and polished, the surface roughness of the finished surface can be improved compared to plunge grinding, and local wear of the grindstone can be prevented, and moreover, when the shape of the cup grindstone changes due to wear. Can easily avoid the influence on the finished surface by controlling the depth of cut. As a result, it becomes possible to maintain excellent processing accuracy for a long period of time.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a chuck mounted on a spindle (not shown) of a grinding machine, 2 is a ceramic ring-shaped component, and the ring-shaped component 2 is attached to the chuck 1 by a jig 3 and is the same as the spindle. Is rotated about the axis A of. Reference numeral 4 denotes a cup grindstone having an inner diameter larger than the thickness of the ring-shaped component 2, and an open end surface thereof is provided with an abrasive grain layer 4a formed by bonding diamond abrasive grains or CBN abrasive grains with a metal bond. The cup grindstone 4 is rotated by a grindstone driving device (not shown) around an axis B orthogonal to the rotation axis A of the ring-shaped component 2, and
It is sent along the axis B to make a predetermined cut.

Next, an embodiment of the spherical surface processing method of the present invention will be described. As the ring-shaped part 2, diameter: 90 m
m, thickness: 25 mm, an outer ring for ball bearings made of silicon nitride (Si ₃ N ₄ ) was used. The outer diameter of the cup grindstone 4 is 60 m
m, width of abrasive grain layer 4a: 5 mm, binder: metal bond,
Particle size: # 140 was used. The outer ring was attached to the main shaft of the universal tool grinder and rotated at a speed of 200 rpm, and the cup grindstone was attached to the output shaft of the grindstone drive, and the speed was 250.
The cup grindstone was rotated at 0 rpm to make a cut, and a spherical surface having a radius of curvature of 45 mm was machined on the outer circumference of the outer ring. After processing, the finished surface of the outer ring was measured, and sphericity: 3 μm,
The surface roughness Ra was 0.2 μm. It is considered possible to obtain a sphericity of 3 μm or less by improving the accuracy of the main axis.

Next, a comparative example will be described. As the ring-shaped component 2, an outer ring made of the same material and having the same dimensions as those used in the above embodiment was used. As a whetstone, outer diameter: 350 mm, whetstone width:
A 40 mm, grain size: # 800 electrodeposition formed grindstone was used.
The outer ring is rotated at a speed of 100 rpm, and the shaped grindstone is rotated at a speed of:
After rotating the outer ring of the outer ring spherically at 1,500 rpm and measuring the finished surface of the outer ring, the sphericity is 10μ.
m, surface roughness: Ra 0.3 μm. As described above, according to the present invention, not only the sphericity is dramatically improved as compared with the conventional processing method, but the surface roughness of the processed surface is also better than the conventional processing method even if the grain size of the grindstone is coarse. It is possible to obtain the processed surface roughness.

The cup grindstone 4 is not limited to the one shown in FIG. 1, but is provided with a plain body as shown in FIG. 2, a dish-shaped one as shown in FIG. 3, and the one shown in FIG. It is also possible to use the one having the abrasive grain layer 4a on both end faces. Further, as shown in FIG. 5, the axis B of the cup grindstone 4 is tilted within the rotation plane of the ring-shaped component 2, that is, the axis B of the cup grindstone 4 which is perpendicular to the rotation axis A of the ring-shaped part 2 but does not intersect. It is also possible to rotate around and process, and in this case, the curvature of the finished surface can be arbitrarily changed. In addition, the present invention is not limited to the above-described embodiment, and is applied to spherical surface processing of a metal ring-shaped part, etc., and the shape and configuration of each part are appropriately changed without departing from the spirit of the present invention. It is also possible to convert.

[0011]

As described in detail above, according to the present invention, since the method of polishing the cup grindstone by rotating it about the axis perpendicular to the axis of rotation of the ring-shaped component is employed, the cost of the grindstone is reduced. It has an excellent effect that it can be reduced and the processing accuracy can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a spherical surface processing method showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another example of a cup grindstone.

FIG. 3 is a cross-sectional view showing another example of a cup grindstone.

FIG. 4 is a sectional view showing another example of a cup grindstone.

FIG. 5 is an explanatory view of a spherical surface processing method showing another embodiment of the present invention.

[Explanation of symbols]

1 ... Chuck, 2 ... Ring parts, 3 ... Jig, 4
..Cup grindstone, 4a ..

Claims (1)

[Claims] 1. A cup grindstone is rotated about its axis while a cup grindstone having an inner diameter greater than the thickness of the ring-shaped part is rotated about an axis perpendicular to the axis of rotation of the ring-shaped part. A spherical surface processing method for a ring-shaped component, which comprises cutting a grindstone to polish the outer periphery of the ring-shaped component into a spherical surface.