JPH08312640A - Sintered bearing and manufacture thereof - Google Patents

Abstract

PURPOSE: To cope with a load applied to an end face of a bearing and produce sintered bearings on a large scale accurately and efficiently by providing a plurality of steel balls or ceramic balls in the recessed groove of the end face of a sintered cylindrical body. CONSTITUTION: Steel balls (or ceramic balls) 19 are provided in a recessed groove 17 of an end face 21 of a sintered cylindrical body 8, and served as rolling objects in the recessed groove 17. A shaft journal 25 of a rotary part 23 is contacted with the steel balls 19 on the end face 21 of a sintered bearing, and a plurality of the steel balls 19 on the end face 21 of the sintered cylindrical body act as a bearing against a load applied to the shaft journal 25 in the direction of the rotary shaft. Further, recompression for improving sizing, coining, and density increasing for improving physical property is simultaneously executed by pressingly grinding the upper and lower both faces of the sintered cylindrical body 8, and hence the sintered bearings can be produced on a large scale accurately and efficiently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered bearing having a steel ball or a ceramic ball on its end face and a method for manufacturing the same, and more particularly to a sintered bearing such as an oilless bearing whose density is corrected and ground. The present invention relates to a sintered bearing having balls or ceramic balls and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, when powder is placed in a mold and compressed,
To increase the density of the green compact, it is required to increase the compression force, but it is difficult to increase the density beyond a certain limit due to the ability of the press and the strength of the mold. Therefore,
Coining and sizing of the sintered product have been conventionally performed, but when it is desired to grind the end face, lathe grinding is usually performed as a secondary process. But,
This is very troublesome to process and is not suitable for mass production of oilless bearings. Therefore, conventionally, a technique has been proposed in which a sintered product is put into a mold, and a punch for pressing the sintered product and a rotating punch provided in the core of the punch are used to correct the density of the sintered product and grind the end surface. Has been done (Actually Ko 55-401
73).

[0003]

In the above-mentioned prior art, the density of the sintered product is corrected and the end surface is ground, and the work efficiency can be improved, but the end surface of the sintered bearing is ground. However, there is a problem in that a sintered bearing that has only been subjected to oil impregnation cannot handle a load that is applied to the end surface of the sintered bearing, that is, a journal that is subjected to an axial load. For example, there is a problem in that when the journal, which is axially loaded, rotates at high speed, or when the axial load is large, smooth rotation is not performed and heat is generated. Therefore, in the present invention, a sintered bearing having a steel ball or a ceramic ball on the end face so as to be able to cope with a load applied to the end face of the bearing, and mass production of such a sintered bearing with high precision and efficiency can be performed. The present invention provides a manufacturing method capable of

[0004]

Means for Solving the Problems The present invention is to solve the above problems, and a plurality of steel balls or ceramic balls are provided in the groove of the end surface of a sintered cylindrical body which is sintered, straightened, and oil-impregnated. The inner peripheral surface of the sintered cylindrical body acts on the rotary shaft circumferential journal, and the plurality of steel balls or ceramic balls on the end surface of the sintered cylindrical body act on the rotary shaft direction journal. It is a sintered bearing having steel balls or ceramic balls of.

Further, according to the present invention, a step of compressing and forming a cylindrical green compact having an annular concave groove on the end face of the cylindrical body and heating and sintering it, and then using the sintered cylindrical body as a mold Get in,
A cylindrical punch that presses the outer surface of the concave groove on the end surface of the sintered cylindrical body having the concave groove, and an annular convex shape that can be raised and lowered and rotated in the hollow portion of the cylindrical punch and that corresponds to the concave groove at the tip. With a punch provided with a cutter, and by inserting a core lot into the inner peripheral surface of the sintered cylindrical body, the sintering cylindrical body is pressed from both upper and lower surfaces, a straightening step of simultaneously performing grinding, then an oil impregnation treatment, and then A sintered bearing having a steel ball or a ceramic ball on the end surface, characterized by including a step of inserting a steel ball or a ceramic ball into the groove on the end surface of the cylindrical body after sintering, pressing, grinding, oil-impregnated treatment, and performing a retaining process. Is a manufacturing method.

Further, the present invention is a method of manufacturing a sintered bearing having a steel ball or a ceramic ball on an end surface, which is characterized in that a core lot inserted through an inner peripheral surface of a cylindrical sintered body is rotated. Further, according to the present invention, the sectional shape of the annular groove in which the steel ball or the ceramic ball is inserted on the end face of the cylindrical body may be such that the steel ball or the ceramic ball is inserted and acts as a roller bearing. It may be a groove, a V groove, or a groove having a pentagonal bottom surface.

[0007]

In the present invention, the steel balls or the ceramic balls are provided on the end surface of the sintered bearing in response to the load applied to the end surface of the sintered bearing. Even if the axial load is large in contact with the shaft journal, it can be smoothly rotated by a small and thin sintered bearing. In addition, sizing, coining, and recompression for improving physical properties such as increasing density are performed by pressing and grinding from the upper and lower surfaces of the sintered cylinder at the same time to mass produce sintered bearings with high accuracy and efficiency. Is something that can be done.

[0008]

Embodiments of the present invention will be described with reference to the drawings. [Embodiment 1] FIG. 1 shows a first embodiment of the present invention. FIG.
(A) is a cross-sectional view of the sintered bearing of the present invention, in which a sintered cylindrical body (8) which has been sintered, straightened, and impregnated with oil has an end surface (2).
A steel ball (or a ceramic ball) (19) is provided in the concave groove (17) of the steel ball (1).
Reference numeral 9) is a groove (17) which functions as a roller. The inner peripheral surface (22) of the sintered cylindrical body (8) is formed smoothly by straightening the sintered cylindrical body.

FIG. 1 (b) shows the sintered bearing of the present invention and the shaft journal of the rotating portion. The steel journal (25) of the rotating part (23) is in contact with the steel ball (19) of the sintered bearing end face (21), and the plurality of steel balls (19) of the sintered cylinder end face (21) are The bearing acts on the load applied to the shaft journal (25) in the direction of the rotation axis, that is, in the vertical direction in the figure. The inner peripheral surface (22) is in contact with the shaft journal (24) of the rotating portion (23) and acts as a bearing. With such a sintered bearing having a plurality of steel balls in the end surface concave groove, even if the shaft journals (24) and (25) of the rotating portion (23) rotate at high speed, or even if the axial load is large, Is rotated.

In order to smoothly rotate the rotating portion (23), the sintered cylindrical body (8) is raised (the inner peripheral surface (22) is lengthened), and a long shaft journal (24) axially attached to it.
However, in the sintered bearing of the present invention, the sintered ball of the end surface of the sintered bearing is in contact with the shaft journal of the rotating portion and is small in axial load and thin in thickness. It can be smoothly rotated at a high speed by the coupling bearing.

[Second Embodiment] A second embodiment of the present invention will be described with reference to FIGS. 2 (a) to 2 (c) are diagrams for explaining compression formation of a green compact, FIG. 3 is a diagram for explaining a step of press grinding a sintered cylindrical body, and FIG. 4 (a) is a step of press grinding. FIG. 2B is an enlarged plan view of the annular convex cutter of FIG.
Is a cross-sectional view of the sintered cylindrical body, FIG. 5 is a view for explaining taking out after the step of performing pressure grinding, and FIGS. 6A to 6C are steps of putting a steel ball in the end surface concave groove and performing a retaining process. And FIGS. 7A and 7B are views showing a sintered bearing having steel balls on the end faces.

First, as shown in FIG. 1 (a), the compression molding of a cylindrical green compact having an annular groove on the end face of the cylindrical body is performed by placing a core lot (7) from below in the center of the die (2). The projected cavities are filled with powder and compressed. The compression from above is a cylindrical first upper punch (3) having a pressing die (5) and a cylindrical first punch (3) which can slide on the inner surface of the cylinder and at which the lower core lot (7) can be inserted. 2 Upper punch (4). The compression from below is performed by a cylindrical lower punch (6) having a core lot (7) inserted through the center.

In the compression forming of the cylindrical green compact, the pressing die (5) of the first upper punch (3) uses an annular projection (51) as shown in FIG. 2 (b). Two
As shown in (c), an annular groove is formed on the end face of the cylindrical green compact (1). The pressing die for forming the annular groove on the end surface of the cylindrical body is not limited to this, and a plurality of cylindrical punches corresponding to the shape of the annular groove may be slidably provided on the end surface. After the completion of the compression forming of the cylindrical green compact, the upper first punch (3) and the second upper punch (4) above are retracted, and the lower punch (6) is pushed further upward to raise the molded product (1) upward. Push it up to remove.

Next, the compressed and formed cylindrical green compact is heated and sintered at an appropriate temperature and atmosphere. As the material, Cu
-Sn system, Fe-Cu system, Fe system, stainless system, and this sintering step is, for example, 7 if the material is Cu-Sn system.
00-900 ° C, 900-110 for Fe-Cu system
The temperature is 0 ° C., the temperature is 1000 to 1200 ° C. for Fe type, and the temperature is 1000 to 1200 ° C. for stainless type, and the atmosphere is non-oxidizing, for example, hydrogen atmosphere.

Next, the straightening step of simultaneously pressing and grinding the sintered cylindrical body will be described with reference to FIGS. 3, 4 (a), (b) and 5
Shown in As shown in FIG. 3, a sintered cylindrical body (8) is provided between the straightening die (9) and the straightening core lot (14) at the center thereof.
Set. On the end surface of the sintered cylindrical body (8) having the concave groove, there is provided a first upper punch for correction (10) which is a cylindrical punch for pressing the outer surface of the concave groove, and a cylinder of the first upper punch (10). The second upper punch for correction (11) is provided so that the hollow part can be moved up and down and can be rotated. The second straightening upper punch (11) is provided with an annular convex cutter corresponding to the concave groove of the sintered cylindrical body (8).

A core lot for correcting the core portion (14) is inserted through the inner peripheral surface of the sintered cylindrical body (8). The straightening core lot (14) can move up and down the core of the straightening lower punch (13). The end surface having the concave groove on the upper surface of the sintered cylindrical body (8) is the second upper punch (11) rotating with the first upper punch (10), and the lower surface thereof is the lower punch (1).
Pressed in 3).

FIG. 4A shows an annular convex cutter (12) at the tip of the second straightening upper punch (11), which has an annular shape corresponding to the concave groove on the end surface of the sintered cylindrical body. The convex mold (15) is provided, and the annular convex mold (15) is provided with a plurality of grooves (16). In the step of straightening the sintered cylinder, the sintered body (8) is put into the die (9) and pressure is applied, sizing to obtain the required size, coining to clarify the surface shape, increasing density, etc. Re-compression is performed to improve physical properties, and particularly in the oil-impregnated bearing of the present invention, sizing is mainly performed for coining and re-compression.

Immediately, the annular projection (1) shown in FIG.
By rotating the straightening cutter (12) provided with the groove (16) acting as a blade in (5), the annular recess (17) on the upper surface of the sintered body (8) shown in FIG. It is a mirror finish. Further, the hole at the center of the sintered body (8) in FIG. 4 (b) is the core hole for straightening (1) shown in FIG.
It is sized according to 4). In order to perform this sizing more efficiently and to achieve high dimensional accuracy,
It is desirable to rotate the straightening core lot (14).

FIG. 8 (a) shows another embodiment of the straightening cutter (12) and the annular recess (17). The annular projection (15) is angular, and the annular recess (17) is shown. Is also square. It is to be noted that this is one in which an annular recess is formed in a square shape when the cylindrical green compact is formed by compression. After the straightening process is completed, as shown in FIG. 5, the straightening first upper punch (10) and the straightening second upper punch (11) are retracted upward, and the straightening lower punch (13) is pushed up to form a die ( The sintered body (8) straightened from 9) is taken out.

Next, the sintered body is subjected to oil impregnation treatment. To impregnate oil with oil impregnation, for example, put the sintered body in a container and depressurize it, pour lubricating oil into this container, put it under depressurization, and replace the oil with air in the pores of the sintered body. Enter. Alternatively, it may be immersed in oil without being depressurized.

Next, as shown in FIG. 6 (a), a desired number of steel balls (19) are inserted into the annular recesses (17) on the upper surface of the sintered body (8). Then, as shown in FIG. 6 (b), the push-up tool (20) is used for caulking. The push-up tool (20) is a tubular tool whose only cross-section is shown, but is a tool for crimping the push-up surface, which is for crimping a steel ball (19) put in an annular recess (17). . Then, the push-up tool (20) is crimped, and the recess (17) of the sintered body (8) is deformed as shown in FIG. 6 (c) to prevent the steel ball (19) from coming out. Figure 7
As shown in (a) and (b), a steel ball (19) is inserted on the upper surface of the sintered bearing or sintered body (8) manufactured by the process of the present invention.

[0022]

As described above, according to the present invention,
By having steel balls or ceramic balls on the end surface of the sintered bearing, it has the effect of being able to handle the load applied to the end surface, and also in order to obtain the required dimensions, especially in the straightening step of the manufacturing method, sizing, surface Of the sintered cylindrical body with high precision and efficiency by performing coining to clarify the shape of the sintered compact and recompression for improving the physical properties to increase the density by pressing and grinding from the upper and lower surfaces of the sintered cylinder at the same time. The effect is that it can be mass-produced.

[Brief description of drawings]

FIG. 1 is a sectional view of a sintered bearing according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating formation of a green compact according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a correction process according to an embodiment of the present invention.

FIG. 4 is an enlarged plan view of a cutter and a cross-sectional view of a sintered cylinder used in a straightening process according to an embodiment of the present invention.

FIG. 5 is a view for explaining taking out after the correction process according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating a step of performing retaining processing according to an embodiment of the present invention.

FIG. 7 is a sketch drawing of a sintered bearing according to an embodiment of the present invention.

FIG. 8 is an enlarged plan view of a cutter and a cross-sectional view of a sintered cylinder used in a straightening process according to another embodiment of the present invention.

[Explanation of symbols]

 1. Green compact 2. Dice 3. First upper punch 4. Second upper punch 5. Mold 51. 5. Press-shaped convex portion 6. Lower punch 7. Core lot 8. Sintered cylinder 9. Straightening die 10. First upper punch for straightening 11. Second upper punch for straightening 12. Annular convex cutter 13. Lower punch for straightening 14. Orthodontic core lot 15. Annular convex type 16. Annular convex groove 17. Groove 19. Steel balls or ceramic balls 20. Sintered bearing end face 22. Inner peripheral surface of sintered cylindrical body 23. Rotating part 24.25. Axis journal

Claims (3)

[Claims] 1. A plurality of steel balls or ceramic balls are provided in an end groove of a sintered, straightened and oil-impregnated sintered cylindrical body, and an inner peripheral surface of the sintered cylindrical body serves as a rotary shaft peripheral journal and is sintered. A sintered bearing having a plurality of steel balls or ceramic balls in the groove of the end face, wherein a plurality of steel balls or ceramic balls on the end face of the cylindrical body act on the journal in the rotation axis direction. 2. A step of forming and sintering a cylindrical green compact having an annular groove on the end surface of a cylindrical body, and placing the sintered cylindrical body in a mold, and the end surface of the sintered cylindrical body having the groove. Is a cylindrical punch that presses the outer surface of the concave groove, and a punch that can move up and down in the hollow portion of the cylindrical punch and has an annular convex cutter corresponding to the concave groove at the tip, By inserting the core lot into the inner peripheral surface of the sintered cylindrical body, pressing the sintered cylindrical body from the upper and lower surfaces,
2. The method according to claim 1, further comprising a straightening step of simultaneously performing grinding, an oil impregnation step, and then a steel ball or a ceramic ball is inserted into the groove on the end surface of the sintered cylindrical body to perform a retaining process. Manufacturing method of sintered bearing. 3. The method for producing a sintered bearing according to claim 2, wherein the core lot inserted through the inner peripheral surface of the cylindrical sintered body is rotated.