JPH028302A - Manufacture of sintered bearing material - Google Patents

Abstract

PURPOSE:To obtain a product having suitable non-contacting range at intermediate part in the inside by charging raw material powder into a gap between a core having step and a metallic mold, compacting and sizing while drawing after sintering. CONSTITUTION:The raw material powder is charged into the gap between the core 1 forming the step part 1c at interval of comparatively small diameter part 1a and comparatively large part 1b and the metallic mold 2, and by operating punches 3, 3a, the powder is compacted and the green compact is sintered. This sintered body is charged toward deep drawing part 16 of a metallic mold 15 and straightening drawing forming is executed with a small diameter lower punch 13a operated along a lower guide core 11b and an upper punch 13a pressing down along a sizing core 11a. This product has the compacted bearing face 14b formed with the relatively large diameter part 1b, and forms the drawn bearing face 14a at the other end face side and the non-contacting face 14c between the bearing faces 14a, 14b. By this method, the product having a high damping function to a shaft 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, and is a method for properly manufacturing a product having a precise non-contact area in the middle part of the inner diameter of the sintered bearing material. I'm trying to find a way to do it.

(Industrial application field) A sintered bearing material that reduces friction by forming a non-contact area in the middle of the inner diameter surface.

(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.

In cases where the rotary shaft is supported at two places using traditional metal as described above, each bearing length may be short, but it is important to achieve coaxiality between the two bearings. Have difficulty. If we try to support the shaft with a single piece of metal to eliminate the coaxiality described above, the axial length of the bearing material will become large, and in a bearing with such a large axial length, the contact area with the rotating shaft will increase. Since the friction becomes large and the temperature of the bearing body during continuous operation also increases, it is necessary to form a relief in the middle of the inner diameter surface of the bearing material as described above so that it does not come into contact with the shaft material. There is. 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 powder-formed sintered bearing materials whose inner diameter surface is generally straight have a large surface friction with the shaft material, and it is particularly difficult to suppress runout when the shaft material rotates. Bearing materials with long bearing lengths have large friction, and the temperature rise during continuous rotation is also high.

In order to avoid this disadvantage, the method described in the previous item (3) is difficult to perform drilling on the inner surface, which increases the number of man-hours and inevitably increases the cost.

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, as mentioned above, the length of the sliding surface on both ends of this product is not accurate due to the lack of accuracy in the shape and structure at the boundary between the bulge molded part and the sliding surface between the sliding surfaces on both ends. It is difficult to ensure the 1-rate property, and it is difficult to obtain an effective supporting action, especially on the load side. In addition, when a bearing with a bulged center part is installed in a housing, the configuration is as shown in FIG. Even if a substantially tight setting can be obtained by doing so, a gap 11 must remain between the other end of the bearing body and the housing 10, making it difficult to obtain a stable set state.

"Structure of the Invention" (Means for Solving the Problem) A core with a stepped portion formed between a relatively small diameter portion and a relatively large diameter portion is used, and the core is inserted between the stepped core and a mold. The powder compacting process involves compacting the raw material powder to form a cylindrical body with internal holes formed on both sides of the stepped core described above, and sintering this compacted compact and then performing the comparative process described above. The sintered body is charged into a mold having a sizing core with the same diameter as the small diameter part and a drawing part, and the formed end side of the relatively large diameter part of the stepped core is drawn as described above. 1. A method for manufacturing a sintered bearing material, comprising the step of sizing while drawing and forming between a sizing core and a sizing core.

(Function) By using a core in which a stepped portion is formed between a relatively small diameter portion and a relatively large diameter portion, a compact having a large diameter portion and a small diameter portion on the inner diameter surface is formed through a powder compacting process, In the sizing process after sintering this product, the forming end side of the large diameter portion described above is drawn to have the same diameter as the small diameter portion.

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 structures, effective bearing action is achieved. In addition, the sliding surface portion formed with a smaller diameter than the stepped portion of the stepped core during powder compaction has a dense structure including the outer diameter side, so by setting this portion as the front side of the bearing, it is possible to The load side is supported accurately. Even if the drawn portion has a small outer diameter, a small diameter portion corresponding to this portion is formed on one side of the housing attachment portion to ensure tight attachment to the housing.

(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 by the method shown in FIG. 2.

That is, in the powder compacting shown in FIG. 1, raw material powder is charged between a core 1 and a mold 2, in which a stepped portion 1c is formed between a relatively small diameter portion 1a and a relatively large diameter portion 1b. The upper and lower punches 3.3a are machined along the core 1 for powder compaction, and the lower punch 3a is relatively thin so as to fit into the gap between the mold 2 and the relatively large diameter portion 1b. As shown in the figure, the upper punch 3 is thicker than the upper punch 3.

The molded body obtained by the method shown in FIG. 1 as described above is as shown in FIG. The portion molded with the target small diameter portion 1a is formed as a sliding surface having small diameter holes 4b, and this compacted powder body is then subjected to a sintering process to form a sintered body 4.

The sintered body obtained as described above is then subjected to a sizing treatment using the equipment shown in FIG. The guide core llb is used, and the mold 15 is provided with a constricted part 16, and the sintered body 4 is charged into the constricted part 1G of the mold 15, and the lower guide core llb is
A target product 14 is formed by corrective drawing using a small-diameter lower punch 13b that is operated along the sizing core lla and an upper punch 13a that is rolled down along the sizing core lla.

That is, the obtained product is as shown in FIG. 4, and has a powder-molded bearing surface 14b formed with the above-mentioned relatively large diameter portion 1b on the end surface side, and a sizing core on the other end surface. A drawn bearing surface 14a formed by the drawing part 16 of the mold is formed on the lla, and these bearing surfaces 14
A non-contact surface 14C formed by the relatively large diameter portion 1b described above is formed between a and 14b, and as shown in the figure, this non-contact surface 14C is accurate and considerably large. It is.

In the above-mentioned one shown in FIG. 2, if the joint between the lower guide core 11b and the sizing core lla is uneven, the relationship between the guide core and the sizing core may be reversed, and the sizing core may be protruded downward to the upper bunch area. LJ may be joined to a guide core from above within the upper punch 13a. After compaction or swissing, the compacted product or the sized target product can be easily taken out by moving the lower punch 3b or 13b with the upper bunch 3 or 13a or the upper punch 13a and the sizing core lla pulled up. be able to.

An example of a state in which the bearing according to the present invention is installed in the housing 1o is as shown in FIG. 5, and the outer diameter of the portion formed by the above-mentioned constricted portion 16 is smaller than the other portion. It is obvious that the housing 10. :! : Installation can be achieved without leaving any gaps. In other words, in the conventional type shown in Fig. 6, which has the reduced outer diameter portions on both ends, even if one of the parts could be tightly attached to the housing sink, the other would remain unstable with a gap left. In contrast, the device of the present invention, in which only one side has a smaller diameter, can be accurately installed in eight sinks. The portion 14b formed with a relatively smaller diameter than the stepped portion 1c is a solid bearing structure portion even though it has a relatively large diameter, and is suitable for supporting the load side 20a of the shaft member 20. Preferably it is equipped to support the load side 20b.

``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, Because it is formed by effective compaction or compression molding between the drawn part and the guide core, it has excellent strength and is dimensionally accurate.Furthermore, since it is an integrally molded material, coaxial It is clear that it is possible to set a high It is possible to appropriately manufacture even relatively long bearing materials, thereby effectively providing low-cost products or products with high shaft vibration prevention properties, so it is industrially popular. This is a highly effective invention.

[Brief explanation of the drawing]

The drawings show the technical contents of the present invention, and FIG. 1 is a sectional view of a compacting mechanism in the method of the present invention, FIG. 2 is a sectional view of a sizing mechanism for the compacting and sintered body, Figure 3 is a partially cutaway side view of the powder compact, Figure 4 is a partially cutaway side view of the product after sizing, and Figure 5 is a partially cutaway side view of the product after sizing.
The figure is a sectional view of the conventional device in a state where it is attached to a housing, and FIG. 6 is a sectional view of a conventional device in a state where it is attached to a housing. In these drawings, 1 is a core, 1a is a relatively small diameter portion thereof, 1b is a relatively large diameter portion, 1c is a stepped portion, and 2
is a mold, 3.3a is a punch, 4 is a compacted or sintered body, 4a is its large diameter inner diameter surface, 4b is a small diameter hole, 10 is a housing, lla is a sizing core, llb is a guide core,
13a and 13b are punches, 14 is a sized product, 14a is a drawing bearing surface, 14b is a powder forming bearing surface,
15 is the mold, 16 is the drawing part, 20 is the shaft +A, 20a
20b shows the load side, and 20b shows the anti-load side.

Claims (1)

[Claims] The above-mentioned stepped core is obtained by using a core in which a stepped portion is formed between a relatively small diameter portion and a relatively large diameter portion, and compacting raw material powder charged between the stepped core and a mold. A powder compacting process to form a cylindrical body with inner holes formed on both sides of the step part, and after sintering this powder compact, a sizing core and a drawing part with the same diameter as the above-mentioned relatively small diameter part are formed. The sintered body that has undergone the above sintering is charged into a mold, and the formed end side formed by the relatively large diameter portion of the stepped core is sized while being drawn between the drawing portion and the sizing core. A method for manufacturing a sintered bearing material, comprising the steps of: