JPH03277814A - Manufacture of oil impregnated sintered bearing - Google Patents

Abstract

PURPOSE:To make a product small, and make it hard to be drawn by engaging a sintered bearing intermediate product in an outer frame, and inserting an elastic core into the bearing intermediate product, compressing the core, and deforming the core into a barrel shape to enlarge a diameter of a part touching the inside diameter face. CONSTITUTION:A sintered bearing intermediate product 20 is engaged in an outer frame 21, and while a lower frame 22 is inserted into an inside diameter hole 23, and a cylindrical core 24 made of an elastic material such as urethane rubber and having a diameter smaller than the inside diameter dimension by about 0.1-2mm is inserted into the inside diameter hole 23. Next, an upper frame 25 is lowered to compress the core 24. The core 24 is thereby deformed into a barrel shape, and a diameter of a part touching the inside diameter face of the bearing intermediate product 20 is enlarged. A small-sized and draw- hard bearing intermediate product, which has an enlarged diameter part 26 in the inside diameter face and above and under which bearing faces 27, 27 are formed, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a sintered oil-impregnated bearing.

[Conventional technology]

In a device having a structure in which a shaft is cantilever-supported, such as a coreless motor, two bearings 3 are disposed close to each other between a shaft 1 and a housing 2, as shown in FIG. These bearings 3 are composed of sintered oil-impregnated bearings, but there are demands such as reducing the variation in the inner diameter dimensions of the two bearings, miniaturizing the structure, improving the efficiency of assembly work, and reducing the price. .

As a sintered oil-impregnated bearing that meets these demands, as shown in FIG. 6.6
A bearing having an integrated structure that supports the shaft 1 is desired.

In order to manufacture a bearing with such an integrated structure, a conventionally known method is to manufacture a bearing intermediate product 7 as shown in FIG.
In this method, the inner mold 8 is inserted into the inner diameter hole, and the outer mold 9.9 is placed on both upper and lower ends of the inner mold 8, and compressive force is applied from above and below as shown in FIG. There is a circumferential recess 1 on the inner diameter surface of the outer mold 9.9.
0 exists, the outer diameter surface of the intermediate bearing 7 is located in the recess 1.
Escape to 0.

Therefore, an enlarged diameter portion 11 is formed on the inner diameter surface, and bearing surfaces 12.12 are formed above and below the enlarged diameter portion 11.

[Problem to be solved by the invention]

However, the bearing manufactured by the above method is
The outer diameter surface has a step that protrudes outward, and the outer diameter surface of the stepped portion is fitted into the bearing housing. Therefore, compared to a bearing that is fitted over the entire length of the outer diameter surface of the bearing (see FIG. 5), a stepped bearing has the disadvantage that it is easier to remove if the interference is constant.

Therefore, an object of the present invention is to solve the above-mentioned problems and provide a method for manufacturing a sintered oil-impregnated bearing having a desirable shape as shown in FIG.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a method for manufacturing a sintered oil-impregnated bearing, which includes sequentially performing the steps of powder compacting, sintering, and compression shaping. After the product is molded and subjected to a sintering process or a compression shaping process, a highly elastic core is inserted into the inner diameter hole of the intermediate bearing product, and both end surfaces of the core are compressed with a mold. The diameter of the bearing is enlarged to form an enlarged diameter part in the middle of the inner diameter surface of the intermediate bearing.

〔Example〕

In the method of the embodiment, molding is performed through a powder compacting process, a sintering process, and a compression shaping process in sequence, as in the conventional case.

In the powder compaction process, a sleeve-shaped bearing intermediate product is formed using the sintering powder, and this is sintered in the next sintering process. As shown in FIG. 1, the sintered intermediate bearing product 20 is
At the same time as fitting the lower mold 22 into the outer mold 21, the lower mold 22 is inserted into the bearing intermediate product 20.
A cylindrical core 24 made of an elastic material such as urethane rubber and having a diameter smaller than the inner diameter by about 0.1 to 2 cm is inserted into the inner diameter hole 23 of the inner diameter hole 23 .

Thereafter, the upper mold 25 is lowered and the core 24 is compressed while applying a constant pressure to the upper end surface of the intermediate bearing product 20. The compressed core 24 deforms into a barrel shape, as shown in FIG. 2, and expands the diameter of the portion that contacts the inner diameter surface of the intermediate bearing product 20. After expanding the diameter, when the core 24 is pushed out, an intermediate bearing product 20 is obtained in which an expanded diameter portion 26 is formed on the inner diameter surface and bearing surfaces 27 and 27 are formed above and below the expanded diameter portion 26, as shown in FIG. .

Note that the step of forming the enlarged diameter portion 26 on the intermediate bearing product 20 is as follows:
As mentioned above, there are cases where this is carried out after the sintering process, and cases where it is carried out after the subsequent compression shaping process.

The intermediate bearing product manufactured in this way is impregnated with lubricating oil and used as a sintered oil-impregnated bearing, but like the ideal bearing shown in Figure 5, the outer diameter surface is a straight cylindrical shape. There is no step, and there is an enlarged diameter section 26 in the center of the inner diameter surface, and bearing surfaces 27, 27 are present on both sides of the enlarged diameter section 260.

〔Effect of the invention〕

As described above, according to the present invention, a sintered oil-impregnated bearing having bearing surfaces in contact with the shaft on both sides of the enlarged diameter portion can be formed from a single bearing.

Therefore, compared to the case where two bearings are used, there is less variation in the inner diameter dimension of the bearing surface, the size can be reduced, and the assembly work is easier. Further, since it has a cylindrical shape with a straight outer diameter surface and its entire length is fitted into the bearing housing, it exhibits a large pullout resistance and has the effect of being difficult to pull out.

[Brief explanation of drawings]

Figures 1 to 3 are cross-sectional views of the manufacturing process of an embodiment of the present invention, Figure 4 is a conventional bearing, Figure 5 is a cross-sectional view of an example of use of an ideal bearing, and Figures 6 and 7. 1 is a cross-sectional view of a conventional example in the manufacturing process. DESCRIPTION OF SYMBOLS 1...Shaft, 2...Housing, 3...Bearing, 4...Bearing, 5...Expanded diameter part, 6... ... Bearing surface, 7 ... Bearing intermediate product, 8 ... Inner mold, 9 ... Outer mold, 10 ... Recess, 11. ...Expanded diameter part, 12...Bearing surface, 20...Bearing intermediate product, 21...
Outer mold, 22...Lower mold, 23...
Inner diameter hole, 24... Core, 26...
- Expanded diameter part, 27...Bearing surface.

Claims (1)

[Claims] (1) In a method for manufacturing a sintered oil-impregnated bearing, which consists of sequentially performing the steps of powder compaction, sintering, and compression shaping, a sleeve-shaped intermediate bearing product is formed using sintering powder, and the sintering step Alternatively, after the compression shaping process, a highly elastic core is inserted into the inner diameter hole of the bearing intermediate product, and both end surfaces of the core are compressed with a mold, thereby increasing the diameter of the core and forming the bearing intermediate product. A method for manufacturing a sintered oil-impregnated bearing, characterized by forming an enlarged diameter part in the middle of the inner diameter surface of the product.