JPH02107705A - Manufacture of sintered bearing material - Google Patents

Abstract

PURPOSE:To obtain a bearing material having a little friction with a rotating shaft by arranging non-contacting part with the rotating shaft in the intermediate inner wall part of the cylindrical sintered bearing material with a sizing device at the time of manufacturing the porous oil-containing bearing material by forming and sintering metal powder. CONSTITUTION:Raw material metal powder is charged into gap between a core 1 and a metallic mold 2 and compacted with a upper and lower punches 3a, 3, and after making a cylindrical formed body, this is sintered to make the sintered body 4. This is set in a sizing core 11 for forming a large diameter part 11a at the inter-mediate part, upper and lower punches 12, 13 and metallic mold 15, and by pressing down the upper punch 12, the sintered body 4 is pressed in gap 14 between the straight part at upper end side of the sizing core 11 and inner face of the metallic mold, and successively, this is pressed in gap between the large diameter part 11a and the metallic mold 15 to execute compressed sizing. This sized material 6 is knocked out from the metallic mold 15. the expanded diameter part without contacting with the rotating shaft at the center pat of the inner wall face is formed and the bearing material having a little friction with the rotating shaft at the time of working the bearing, is obtd.

Description

[Detailed Description of the Invention] "Object of the Invention" The present invention relates to a method for manufacturing a sintered bearing material, which has a precise non-contact area in the middle part of the inner diameter of the sintered bearing material, and has straight outer surfaces on both ends. The object of the present invention is to provide a method for properly manufacturing a product that can form a stable and proper mounting relationship with the housing.

(Industrial Application Field) A sintered bearing material that reduces friction by forming a non-contact area in the middle of the inner diameter surface, and also ensures proper attachment to the housing.

(Prior art) The use of sintered metal materials in oil-impregnated bearings and the like has been practiced for a long time, but the conventional sintered metal bearing materials generally have an inner diameter that is straight in the axial direction. It is. That is, since the inner diameter surface is shaped by the sizing core during sizing after powder compacting and sintering, it is natural that the inner diameter surface becomes straight along the sizing core surface.

When using conventional sintered metal as described above and supporting the rotating shaft at two locations, the length of each bearing may be short, but it is necessary to maintain coaxiality between the two bearings. It is difficult to If an attempt is made to support the shaft with a single piece of sintered metal in order to eliminate the coaxiality described above, the axial length of the bearing material will be large, and in a bearing with such a large axial length, it will be difficult to connect the shaft with the rotating shaft. The contact area becomes large and friction becomes large. Furthermore, since the temperature of the bearing body increases significantly during continuous operation, a relief is formed in the middle part of the inner diameter surface of the bearing material as described above so that it does not come into contact with the shaft material. That is, the method is as follows.

■ Mechanical drilling ■ As in JP-A-58-84222, both upper and lower end surfaces and both ends of the outer diameter of a cylindrical sintered body are compressed while being restrained, and the center of the outer diameter is expanded, and the center of the inner diameter is A method of expanding the area to form a non-contact area.

(Problem to be solved by the invention) Conventional general powder compacting b”e where the inner diameter surface is generally straight
Bonded bearing materials have a large amount of surface friction between them and the shaft material, especially bearing materials with long bearing lengths that suppress vibration when the shaft material rotates, and the temperature rise during continuous rotation is also high. .

In order to avoid this disadvantage, the method described in the previous item (2) is difficult to perform drilling on the inner surface, which increases the number of man-hours and inevitably increases costs.

Although it can be said that the method according to the previous item (■) eliminates the disadvantage of the above case (■), since it utilizes the phenomenon of swelling during compression operation, it tends to be unable to secure an accurate shape structure, and it also has a tendency to be difficult to maintain in terms of strength. Since it tends to be insufficient, it requires a certain wall thickness and is relatively short and small. Furthermore, the shape of the outer surface of both ends of this product is a small diameter part, that is, only the middle part is bulged as described above, so when installing a bearing with a bulged center part like this in a housing, Even if a substantially tight setting can be obtained by leaving gaps on both sides of the housing and creating a special configuration in which one side of the housing has a size and shape that matches the outer diameter of one end of the bearing body. A gap must still be left between the other end of the bearing and the housing, making it difficult to obtain a stable centrifugal state.

"Structure of the Invention" (Means for Solving the Problems) A powder compacting process in which raw material powder charged between a core and a mold is compacted into a cylindrical body, and this compacted cylindrical body. After sintering the body, the middle part of the forming area is inserted between the sizing core, which has a large diameter, and the sizing mold, and sizing is performed using upper and lower punches, and the large diameter part of the middle part of the forming area of the sizing core is sintered. forming an enlarged diameter region in the middle part of the inner hole of the molded cylindrical sintered body, then extruding the sizing body together with the sizing core from the mold, and then extracting the sizing core by a spring bank of the sizing body. A manufacturing method for sintered bearing materials.

(Function) By inserting a compacted sintered cylindrical body between a sizing core and a sizing mold in which the middle part of the forming area is made large in diameter and sizing, the middle part of the inner hole becomes the large diameter part. A sizing body with an expanded diameter is obtained.

After this sizing, the sizing body is taken out from the mold along with its core to obtain a spring bank in the sizing body, and the core size is 10 μm or less in one ship due to the taper at the boundary with the large diameter part of the sizing core. The diameter part can be easily pulled out.

After sizing, both the inner and outer surfaces of the product are formed as compacted powder or compression molded layers, which stabilizes the structure and dimensions to be uniform and provides appropriate strength.

Therefore, even products with relatively thin layers or relatively long products with a length larger than the outer diameter can be appropriately manufactured. Since the sliding surfaces for the shaft members on both ends are molded with precise dimensions and structure, a constant bearing action is achieved. Moreover, the inner diameter of the product including both ends is straight like that, so no special machining is required at the housing attachment part, and moreover, it can always be attached to the housing in a tight state.

(Example) To explain the specific embodiment of the invention as described above, which is shown in the attached drawings, in the present invention, compaction is performed by the operation method shown in FIG.
Next, after sintering the powder compact, sizing is carried out in a stepwise manner as shown in FIG.

That is, the powder compacting shown in FIG. 1 is exactly the same as that which has been conventionally performed, in which raw material powder is charged between a core 1 and a mold 2, and then upper and lower punches 3. 3a is operated along the core 1 and compacted to form a molded body with straight inner and outer surfaces.

The powder compact obtained by the method shown in FIG. 1 as described above is then subjected to a sintering treatment to form a sintered body 4 as shown in FIG. 1(B).

The sintered body obtained as described above is then subjected to sizing treatment through various steps as shown in FIG.
A sizing core 11, upper and lower bunches 12, 13, and a mold 15 are used.

That is, first, as shown in the same figure (A), the above-described sintered body 4 is set with the upper end of the sizing core 11 aligned with the upper surface of the mold 15, and when the upper punch 12 is pressed down, the sintered body 4 is is press-fitted into the gap 14 between the upper straight portion 11b of the sizing core 11 as described above and the inner surface of the mold, and then press-fitted between the large-diameter portion 11a and the mold 15. The amount of increase in diameter of the large diameter portion 11a relative to the outer diameter of the sizing core 11 is determined in order to effectively reduce friction against the shaft material as a product bearing.
- Approximately 5 to 10 μm is sufficient for boat fishing, and it is relatively easy to press fit between the large diameter portion 11a made to this large diameter and the inner surface of the mold 15, as shown in Fig. 2 (B). Then, by applying pressure from the lower bunch 13, it is compressed and sized as shown in FIG. 2(C).

As shown in FIG. 2(C), the lower punch 13 and the sizing core 11 are both compressed and sized in the mold 15.
As the sizing material 6 is pushed up, the sizing material 6 is knocked out as shown in FIG. 2(D). As shown in Fig. 2, the sizing material 6 compressed during sizing is spring-hacked due to such knockout, and a certain gap is created between the inner hole and the molding area of the sizing core 11.
D), and when the sizing core 11 is appropriately pulled out together with the lower punch 13 in this state, only the sizing material 6 remains on the mold 15 as shown in FIG. 2(E).

That is, as shown in FIG. 2 (E), the sizing material 6 remaining on the mold 15 is discharged outside the molding area as shown in FIG. Returning to the state, the same sizing as described above is repeated for a new sintered material 4.

Regarding the above-mentioned sizing process, the details of the spring bank of sizing material as shown in Figure 2 (D) will be explained in detail. When the sizing material 6 is later pulled out from the mold 15, its inner and outer diameters are +0.1 to +0.2% larger than the mold dimensions.
It has been confirmed through studies by the present inventors that the diameter can be increased to a certain degree. In other words, even though there are some variations depending on the material, structure, etc., under general sizing conditions, the above spring bank amount is obtained, and the dimensions of the large diameter portion 11a of the sizing core are set within this spring back amount. By increasing the diameter, the sizing core 11 having such a large diameter portion 11a can be pulled out approximately appropriately. Since elastic deformation of the sizing material 6 is also obtained during this drawing, it is clear that the drawing is substantially easy.

For example, when the inner hole diameter of the sizing material 6 is 8.00 mm, the inner diameter of the enlarged diameter portion of the sizing material 6 is 8.0 mm.
We have examined many products with a diameter of 5 to 8.010*n, but none of them have any problems, and smooth sizing can be achieved.Furthermore, such an enlarged diameter portion sufficiently reduces friction against the shaft material. be able to.

The thus obtained product according to the present invention has a straight outer diameter, so there is no need to worry about attaching it to the housing, and since the middle part of the inner hole is exactly recessed, it can be easily supported. The frictional resistance between the shaft member and the other shaft member is small, and coaxiality is also accurate since the shaft member is integrated.

``Effects of the Invention'' According to the present invention as described above, it is possible to form a precise non-contact surface with the shaft material on the inner diameter surface, thereby effectively reducing friction during bearing operation, and moreover, it is possible to effectively reduce the friction as a whole. It is clear that since it is formed by powder molding or compression molding, it has excellent strength and can be obtained as a product with accurate dimensions, and since it is an integrally molded material, it is possible to set a high degree of coaxiality. Moreover, there is nothing to worry about when installing the outer surface to the straight housing.
This invention is industrially very effective because it can provide a bearing material that can be easily and consistently set stably and accurately at a low cost.

[Brief explanation of drawings]

The drawings show the technical contents of the present invention, and Fig. 1 is a sectional view of the compaction mechanism in the method of the present invention, and Fig. 2 shows each process of the sizing mechanism for the compacted sintered body. It is a sectional explanatory view shown step by step. However, in these drawings, ■ is the core, 2 is the mold, and 3 is the core.
, 3a is a punch, 4 is a sintered body, 6 is a sizing material, 10
is the housing, 11 is the sizing core, lla is the large diameter part, llb is the stray 1~ section, 12 is the upper punch, 13
14 is a lower punch, 14 is a gap, and 15 is a sizing mold.゛Sardine 5 (:LHL

Claims (1)

[Claims] A powder compaction process in which the raw material powder charged between the core and the mold is compacted into a cylindrical body, and after this compacted cylindrical body is sintered, the middle part of the forming area is formed into a large diameter The sizing core is inserted between the sizing core and the sizing mold, and sized using upper and lower punches. 1. A method for manufacturing a sintered bearing material, which comprises forming an enlarged diameter region, extruding a sizing body together with a sizing core from a mold, and then extracting the sizing core by springback of the sizing body.