JPH04307112A - Oil-impregnated sintered bearing and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide an oil-impregnated sintered bearing, whose inner diametral part, excellent in a frictional characteristic, is of hourglass form, and its manufacture. CONSTITUTION:A bearing hole 12 of a bearing body 10 made up of a porous sintered alloy is composed of a sliding surface 13, being formed along the intermediate part in the circumferential direction, and a turning shaft is sliding, and a diametral expanding part 14 being ranged with this sliding surface 13 and expanding the diameter in proportion as heading for the outward, and under this constitution, it is composed of crushing a hole of the sliding surface 13. In addition, this oil retaining bearing is manufactured by way of forming the sliding surface 13 after crushing the hole of the inner circumferential surface when frictional force is made to act on the inner circumferential surface surrounding the central part of a through hole, after the diametral expanding part 14 is formed on the inner circumferential surface of this through hole of a sintered body. Since the hole of the sliding surface 13 is crushed, lubricating oil on the sliding surface is in no case leaked out, whereby a firm oil film with no oil-pressure drop on the sliding surface is formed, so any local contact between the turning shaft 11 and the sliding surface 13 is prevented from occurring, thus a frictional factor in the bearing is made reducible.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a sintered oil-impregnated bearing, and more particularly to a sintered oil-impregnated bearing with excellent friction characteristics and a method for manufacturing the same.

0002

[Prior Art] Sintered oil-impregnated bearings, which are formed from a porous sintered alloy and are used after being impregnated with lubricating oil, are widely used as bearings for rotating shafts of various devices because they can be used for long periods of time without lubrication. It is being

As an example of this type of sintered oil-impregnated bearing, for example, as shown in FIG. 5, a bearing hole 2 is formed in a bearing body 1 made of a porous sintered alloy. , formed along the circumferential direction in the middle part thereof, and bearing hole 2
It is known that the rotary shaft 3 is constructed of a sliding surface 4 on which the rotating shaft 3 slides, and a pair of enlarged diameter portions 5, 5 that are connected to the sliding surface 4 and gradually expand in diameter toward the outside. It is being

This sintered oil-impregnated bearing has a configuration in which the rotating shaft 3 inserted into the bearing hole 2 is supported by a part of the bearing hole 2, that is, the sliding surface 4, so that it can be reliably aligned at a predetermined position. The lubricating oil is sucked out from the many fine oil-impregnating holes (holes) in the bearing body 1 by the pump action accompanying the rotation of the rotating shaft 3, and the lubricating oil oozes out due to expansion due to frictional heat. The lubricating oil forms an oil film on the sliding surface 4 of the bearing hole 2, and the rotating shaft 3 is rotatably supported by this oil film.

[0005]

By the way, in the above-mentioned sintered oil-impregnated bearing, since the sliding surface 4 of the bearing hole 2 on which the rotating shaft 3 slides is formed with a large number of holes for impregnating lubricating oil, Even if an oil film is formed, a portion of the lubricating oil leaks from the holes and the oil pressure decreases, resulting in local contact between the rotating shaft 3 and the sliding surface 4. When such localized contact occurs, the friction coefficient of the oil-impregnated bearing increases, resulting in a disadvantage that seizure is likely to occur. Therefore, the present inventors thought that by preventing lubricating oil from leaking from the sliding surface 4, it would be possible to form a strong oil film that would not cause a drop in oil pressure, thereby reducing the friction coefficient of the bearing. We have obtained the following knowledge.

[0006]

Purpose of the Invention The present invention has been made based on the above knowledge, and provides a sintered oil-impregnated bearing that can reduce the coefficient of friction by preventing leakage of lubricating oil from sliding surfaces, and a method for manufacturing the same. is intended to provide.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the sintered oil-impregnated bearing of the present invention has a bearing hole formed in the intermediate portion of the bearing body along the circumferential direction through which the rotating shaft is inserted. , and is composed of a sliding surface on which the rotating shaft slides, and a pair of diameter-enlarging portions that are connected to this sliding surface and gradually expand in diameter toward the outside, and the pores in the sliding surface are crushed. That's what happens.

[0008] In addition, the method for manufacturing a sintered oil-impregnated bearing includes the step of gradually expanding the diameter from the center of the through-hole toward the opening on the inner circumferential surface of the through-hole formed in the sintered body and serving as the bearing hole. An enlarged diameter portion is formed, and then a frictional force is applied to the inner circumferential surface surrounding the central portion of the through hole to collapse the hole in the inner circumferential surface to form a sliding surface on which the rotating shaft slides. It is characterized by

[0009]

[Operation] In the sintered oil-impregnated bearing of this invention, the holes on the sliding surface on which the rotating shaft slides are crushed, so the lubricating oil on the sliding surface does not leak, so the hydraulic pressure is reduced. A strong oil film is formed without deterioration, and the sliding surface and rotating shaft are
Lubricating oil is sufficiently supplied from the inner circumferential surface of the bearing hole other than the sliding surface, that is, the hole in the enlarged diameter portion. Therefore, since there is no local contact between the rotating shaft and the sliding surface, the friction coefficient of the oil-impregnated bearing can be reduced, and bearing characteristics with high service limits can be obtained.

[0010] In addition, in the method for manufacturing a sintered oil-impregnated bearing, after forming enlarged diameter portions at both end openings of a through hole which becomes a bearing hole of a sintered body, an inner circumferential surface surrounding a central portion of the through hole is formed. By applying a frictional force to the pores, the area around the pores on the inner circumferential surface plastically flows into the pores, thereby producing a sintered oil-impregnated bearing having a sliding surface with the pores crushed. Ru.

[0011]

[Embodiment] An embodiment of the sintered oil-impregnated bearing of the present invention and its manufacturing method will be described below. The sintered oil-impregnated bearing shown in FIG. 1 and FIG.
The bearing hole 12 is formed along the circumferential direction in the central part of the bearing hole 12, and has a sliding surface 13 on which the rotating shaft 11 slides, and a sliding surface 13 on which the rotating shaft 11 slides. It is comprised of a pair of diameter-enlarging portions 14, 14 which are connected to each other and whose diameter gradually increases toward the outside. Further, the holes in the sliding surface 13 are crushed to prevent lubricating oil from leaking from the holes.

Next, a method for manufacturing the above-mentioned sintered oil-impregnated bearing will be explained. First, a lower punch is placed at a predetermined position in a die of a normal die set, and powder is filled, and the upper punch is lowered into the die to compression mold a cylindrical green compact. Next, this green compact is taken out from the die and sintered, and then the sintered body is subjected to the following sizing process.

That is, as shown in FIG. 3, the lower punch 16 is positioned inside the die 15, and the sintered body S is inserted into the die 1.
Charge into 5. At this time, the upper punch 18 is kept in standby above.

The lower punch 16 is composed of a cylindrical outer punch 16a and an inner punch 16b slidably provided inside the outer punch 16a. is formed into a tapered shape corresponding to the enlarged diameter portion 14 of the sintered oil-impregnated bearing to be manufactured. The upper punch 18 is composed of a cylindrical outer punch 18a and an inner punch 18b slidably provided inside the outer punch 18a. It is formed into a tapered shape corresponding to the enlarged diameter portion 14 of the sintered oil-impregnated bearing to be used.

Next, the upper punch 18 is lowered into the die 15 to straighten the sintered body S. At this time, by inserting a predetermined amount of the inner punches 16b and 18b into the through hole which becomes the bearing hole 12 of the sintered body, the pair of enlarged diameter portions 14
, 14 are formed.

Thereafter, as shown in FIG. 4, a rotary reamer pin 20 is inserted into the through hole which will become the bearing hole 12 of the sintered body while rotating the pin 20 around the axis. The rotary reamer pin 20 has a cylindrical shape, and its diameter is set to be smaller than the diameter of the enlarged diameter portion 14 and slightly larger than the through hole located between the enlarged diameter portions 14, 14.

When the rotary reamer pin 20 is inserted, the inner circumferential surface located between the enlarged diameter portions 14 and 14 is inserted into the rotary reamer pin 20.
This rotary reamer pin 2
The pores on the inner circumferential surface that are in contact with the pores are crushed by plastic flow into the pores, and the inner circumferential surface where the pores are crushed becomes the sliding surface 13.

According to the sintered oil-impregnated bearing, the holes in the sliding surface 13 on which the rotating shaft 11 of the bearing hole 12 slides are crushed, so that the lubricating oil on the sliding surface 13 leaks. Never. Therefore, a strong oil film is formed on the sliding surface 13 so that the oil pressure does not decrease, and the sliding surface 13 and the rotating shaft 11 are provided with surfaces other than the sliding surface 13, that is, enlarged diameter portions 14, 1.
Lubricating oil is sufficiently supplied from the holes No. 4. Therefore, since there is no local contact between the rotating shaft 11 and the sliding surface 13, the friction coefficient of the oil-impregnated bearing can be reduced, and bearing characteristics with high service limits can be obtained.

Further, according to the above method for manufacturing a sintered oil-impregnated bearing, friction force is applied to the inner circumferential surface surrounding the central portion of the through hole, which becomes the bearing hole 12, by the rotary reamer pin 20, thereby improving the inner circumferential surface. The area around the hole plastically flows into the hole,
As a result, the pores in the sliding surface 13 are crushed. therefore,
Since the lubricating oil on the sliding surface 13 does not leak, a strong oil film is formed on the sliding surface 13 that does not reduce the oil pressure. A sufficient amount of lubricating oil is supplied from the surfaces, that is, the holes in the enlarged diameter portions 14, 14. Therefore, since there is no local contact between the rotating shaft 11 and the sliding surface 13, the friction coefficient of the oil-impregnated bearing can be reduced, and bearing characteristics with high service limits can be obtained.

Furthermore, the bearing hole 12 is formed by sizing processing.
After forming the enlarged diameter portions 14, 14, the rotary reamer pin 20
A sliding surface 13 with flattened holes can be easily formed by rotating and inserting the material into the through hole that becomes the bearing hole 12.

Note that in the above embodiment, the rotary reamer pin 2
Although the holes in the sliding surface 13 were crushed by rotating the slider 0, they may be crushed by vibrating in the axial direction, or by rotating while vibrating.

[0022]

As explained above, according to the sintered oil-impregnated bearing of the present invention, the pores on the sliding surface on which the rotating shaft of the bearing hole slides are crushed, so that the lubrication on the sliding surface is reduced. No oil leaks. Therefore, a strong oil film is formed on the sliding surface that does not reduce oil pressure, and on the sliding surface and rotating shaft,
Lubricating oil is sufficiently supplied from the surface other than the sliding surface, that is, the hole in the enlarged diameter portion. Therefore, since there is no local contact between the rotating shaft and the sliding surface, the friction coefficient of the oil-impregnated bearing can be reduced, and bearing characteristics with high service limits can be obtained.

Furthermore, according to the method for manufacturing a sintered oil-impregnated bearing,
On the inner peripheral surface of a through hole formed in the sintered body to become a bearing hole, an expanding diameter portion is formed that gradually increases in diameter from the center of the through hole toward the opening, and then the center of the through hole is By applying a frictional force to the inner circumferential surface surrounding the slider, a portion of the inner circumferential surface surrounding the hole plastically flows into the hole, thereby crushing the hole in the sliding surface. Therefore, since the lubricating oil on the sliding surface does not leak, a strong oil film is formed on the sliding surface that does not reduce the oil pressure. Lubricating oil is sufficiently supplied from the holes in the enlarged diameter section. Therefore, since there is no local contact between the rotating shaft and the sliding surface, the friction coefficient of the oil-impregnated bearing can be reduced, and bearing characteristics with high service limits can be obtained.

Furthermore, after forming the enlarged diameter portion of the bearing hole, the hole is crushed by applying frictional force to the inner circumferential surface, that is, the sliding surface surrounding the central portion of the through hole that will become the bearing hole. For example, by rotating and inserting a cylindrical pin into the through hole, the hole in the sliding surface at the center of the bearing hole can be easily crushed.

[Brief explanation of the drawing]

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

FIG. 2 is a sectional view taken along the line AA in FIG. 1;

FIG. 3 is a sectional view of a main part of a die set for straightening.

FIG. 4 is a cross-sectional view of the sintered oil-impregnated bearing showing a state in which a rotary reamer pin is inserted.

FIG. 5 is a sectional view showing an example of a conventional sintered oil-impregnated bearing.

[Explanation of symbols]

10 Bearing body 11 Rotation axis 12 Bearing hole 13 Sliding surface 14 Expanded diameter part 20 Rotary reamer pin

Claims (2)

[Claims] Claim 1: A sintered oil-impregnated bearing in which a bearing hole through which a rotating shaft is inserted is formed in a bearing body made of a porous sintered alloy, wherein the bearing hole is formed in an intermediate portion thereof in a circumferential direction. It is composed of a sliding surface formed along the axis of rotation and on which the rotating shaft slides, and a pair of enlarged diameter portions that are connected to this sliding surface and whose diameter gradually increases toward the outside. A sintered oil-impregnated bearing characterized by crushing the pores in the dynamic surface. 2. A method for manufacturing a sintered oil-impregnated bearing in which a bearing hole through which a rotating shaft is inserted is formed in a bearing body made of a porous sintered alloy, wherein the bearing body is made of a porous sintered alloy. An enlarged diameter portion is formed on the inner circumferential surface of the through hole that becomes the hole, and the diameter gradually increases from the center of the through hole toward the opening, and then friction is applied to the inner circumferential surface surrounding the center of the through hole. A method for manufacturing a sintered oil-impregnated bearing, characterized in that a sliding surface on which the rotating shaft slides is formed by crushing holes in the inner circumferential surface by applying force.