JPH06123313A - Oil-impregnated sintered bearing - Google Patents

Abstract

PURPOSE:To reduce the coefficient of friction of an oil-impregnated bearing by crushing symmetrical parts of a hole in the circumferential direction around a point opposite to a side, where a member for transmitting the force to a rotary shaft is arranged, in the axial direction of a bearing main body at the time of green formation. CONSTITUTION:In an oil-impregnated sintered bearing 10, is formed a bearing hole 13, in which a rotary shaft 12 is inserted in a bearing main body 11 made of porous sintered alloy. Among the inner peripheral surface of the bearing hole 13, plural symmetrical parts of the inner peripheral surface of the hole in the circumferential direction around a point Z opposite to a side, where a member for transmitting the force to the rotary shaft 12 is arranged, at 180 degrees in a range of a nearly half-circumference of the side, where the member for transmitting the force to the rotary shaft 12 is arranged, are crushed in the axial direction of the bearing main body 11 at the time of green formation of the bearing main body 11. Leak of the lubricating oil from sliding surfaces S1, S2 is thereby eliminated, and the inner surface between these sliding surfaces S1, S2 is left as a hole and functions as an oil supply part P.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Sintered oil-impregnated bearings, which are made of a porous sintered alloy and impregnated with lubricating oil, can be used for a long time without lubrication and are therefore widely used as bearings for rotary shafts of various equipment. Has been.

As shown in FIG. 3, a sintered oil-impregnated bearing of this type has a bearing hole 2 formed in a bearing body 1 made of a porous sintered alloy, and has a rotation diameter smaller than that of the bearing hole 2. Axis 4
The lubricating oil sucked out from a large number of fine oil-impregnated holes (holes) of the bearing body 1 by the pump action accompanying the rotation of the rotary shaft 4 and the lubricating oil exuded due to expansion due to friction heat An oil film is formed on the sliding surface 4 of the bearing hole 2, and the rotation shaft 3 is rotatably supported by this oil film.

[0004]

By the way, in the above sintered oil-impregnated bearing, a large number of holes for impregnating lubricating oil are formed on the sliding surface 4 of the bearing hole 2 on which the rotary shaft 3 slides. Even if an oil film is formed, a part of the lubricating oil leaks from the holes to reduce the oil pressure, and as a result, the rotating shaft 3 and the sliding surface 4 are locally brought into contact with each other. Thus, there is a drawback that the friction coefficient of the oil-impregnated bearing increases when the local contact is performed.

On the other hand, in order to solve such a problem, for example, a technique disclosed in Japanese Utility Model Laid-Open No. 50-101735 has been proposed.

According to this technique, of the inner peripheral surface of the bearing main body, a substantially half-circumferential portion to which a load is applied is crushed to suppress the leakage of lubricating oil from the sliding surface with the rotating shaft to reduce the oil film. This is to prevent it.

However, even in such a technique, the following problems still remain.

That is, in the above-mentioned conventional technique, since the bearing body is blunted over approximately half the circumference thereof, there are few regions where the holes for supplying the lubricating oil are formed, and depending on the operating condition, sufficient lubrication is provided. There is a problem in that the oil cannot be supplied, and there is also a problem in that the lubricating oil cannot be smoothly supplied to the central part of the mesh because the meshed portion is long.

Further, in a rotating shaft of a forward / reverse rotation motor or the like, the relative positional relationship with respect to the bearing main body changes depending on the rotating direction, so that the lubricating oil supply position changes with respect to the rotating position of the rotating shaft. It is also assumed that the supply form of lubricating oil may be changed.

[0010]

SUMMARY OF THE INVENTION The present invention provides a sintered oil-impregnated bearing capable of effectively solving the problems remaining in the above-mentioned conventional techniques. In a sintered oil-impregnated bearing in which a bearing hole for inserting a rotary shaft is formed in a bearing main body formed of a coupling metal, in an inner peripheral surface of the bearing hole, a substantially half circumference of a side on which the rotary shaft slides. Within the range, a plurality of holes symmetrical in the circumferential direction centering on a point opposed to the side on which the member for transmitting force to the rotating shaft is arranged on the inner peripheral surface by 180 ° are formed, It is characterized by being crushed in the axial direction of the bearing body during molding.

[0011]

In the sintered oil-impregnated bearing according to the present invention, of the inner peripheral surface of the bearing hole, a force is transmitted to the rotary shaft at the inner peripheral surface at a substantially half circumference on the sliding side of the rotary shaft. Since a plurality of holes symmetrical in the circumferential direction centering on a point opposed to the side on which the member is arranged by 180 ° are crushed in the axial direction of the bearing body during powder compaction of the bearing body, the sliding surface The lubricating oil above does not leak, the oil pressure does not decrease, a strong oil film is formed, and holes remain between the sliding surfaces. Also, the lubricating oil is supplied, and the lubricating oil is sufficiently supplied to the sliding surface and the rotating shaft. Therefore, since the rotary shaft and the sliding surface are not brought into local contact with each other, the friction coefficient of the oil-impregnated bearing can be reduced, and the bearing characteristics with high usage limit can be obtained.
On the other hand, the inner peripheral surface is formed by crushing holes in a plurality of planes symmetrical about a point opposite to the side on which the member for transmitting force to the rotary shaft is arranged by 180 °. Even if the position of the rotary shaft is displaced due to normal rotation or reverse rotation, the sliding surface is positioned corresponding to that position, and the holes are positioned on both sides of this sliding surface, thereby providing lubrication. Oil supply conditions are made uniform. further,
Since the holes of the sliding surface are crushed during the powder compaction of the bearing body, the plastic deformation of the sliding surface is smoothly performed, and the holes are reliably crushed.

[0012]

EXAMPLE An example of a sintered oil-impregnated bearing according to the present invention will be described below. The sintered oil-impregnated bearing 10 shown in FIG. 1 has a bearing body 11 made of a porous sintered alloy, a rotary shaft 12
The bearing hole 13 into which the rotary shaft 12 slides is formed in the inner peripheral surface of the bearing hole 13. 18 on the side where the member for transmitting force to the rotary shaft 12 is arranged
A plurality of holes (sliding surfaces indicated by S1 and S2 in FIG. 1) which are symmetrical in the circumferential direction about the point Z facing each other by 0 ° are formed in the axial direction of the bearing body 11 when the above-mentioned bearing body 11 is compacted. The lubricating oil is prevented from leaking from the sliding surfaces S1 and S2 by crushing it into the oil supply section P having holes left on the inner surface between the sliding surfaces S1 and S2. There is.

Next, a method for manufacturing the sintered oil-impregnated bearing will be described. First, as shown in FIG. 3, the cylindrical lower punch 16 is positioned at a predetermined position in the die 15 of the die set used for normal powder molding, and the cylindrical core rod 17 is attached to the upper surface of the die 15. And make it flush. At this time, the upper punch 18 is made to stand by above the die 15.

Here, on the outer peripheral surface of the core rod 17,
Twisted portions 19 having a surface roughness higher than those of other portions are formed at two locations spaced apart in the circumferential direction (only one location is shown in the drawing). These rough parts 1
9 is formed to extend in a belt shape in the axial direction of the core rod 17, and is formed to be slightly recessed from the outer peripheral surface of the core rod 17.

The width of each of the roughened portions 19 in the circumferential direction is determined by sliding along the axial direction in which the rotary shaft 12 slides in the inner peripheral surface of the bearing hole 13 of the sintered oil-impregnated bearing to be manufactured. Surface S
It is set to a size corresponding to the width of 1 · S2, specifically, a width that allows for shrinkage due to sintering of the green compact to be molded, and the sliding surface S1 · S2 It is formed with an interval that allows for the above-mentioned contraction in accordance with the interval.

The roughened portion 19 is formed by electric discharge machining, and a large number of fine convex portions are formed on the surface thereof. The surface roughness of the roughened portion 19 is appropriately selected according to the particle diameter of the powder to be molded, but in this embodiment, it is 5 to 5.
It is set to 10S.

Next, after the powder is filled in the die 15, the upper punch 18 is lowered into the die 15 to compression-mold the powder into a cylindrical shape. At this time, since the roughened portions 19 are formed at two positions of the core rod 17, the holes on the surface of the green compact which are in contact with these roughened portions 19 are
The peripheral portions of the holes are pressed by the large number of convex portions of each roughened portion 19 and plastically flow into the holes to be crushed. Also, the roughened part 1
Since 9 is slightly recessed as described above, the portion in contact with the roughened portion 19 of the molded green compact, that is, the sliding surface 13
The part that becomes is slightly protruding.

Then, the green compact thus formed is taken out from the die 15 and sintered at a predetermined temperature to obtain a sintered body. This sintered body has sliding surfaces S1 and S2 when pressed.
Since the holes on the surface corresponding to are crushed, the holes 13 on each of the sliding surfaces S1 and S2 of the sintered body are crushed, and both sliding surfaces S1
The holes of the bearing holes 13 between S2 and on both sides thereof are left.

Then, this sintered body is incorporated into a die set (not shown) similar to the above, and compressed and subjected to a sizing process to correct each part of the sintered body to manufacture a sintered oil-impregnated bearing. . During the sizing process, the slightly protruding sliding surfaces S1 and S2 are pressed by the core rod of the die set to be flush with the inner peripheral surface of the bearing hole 13, and the sliding surfaces S1 and S2 are also formed. Is smoothed.

According to the sintered oil-impregnated bearing 10, however, the holes of the sliding surfaces S1 and S2 of the inner peripheral surface of the bearing hole 13 along the axial direction in which the rotary shaft 12 slides are crushed. And, since the crushing is performed at the time of the powder compaction of the bearing body 11, the holes are surely crushed, whereby
The lubricating oil on the sliding surfaces S1 and S2 does not leak. Therefore, a strong oil film is formed on the sliding surfaces S1 and S2 so that the hydraulic pressure does not decrease, and the sliding surfaces S1 and S2 and the rotary shaft 12 are
Between the sliding surfaces S1 and S2 and between these sliding surfaces S1
The lubricating oil is sufficiently supplied from the holes on the inner peripheral surface of the bearing hole 13 located on both sides of S2. Therefore, since the rotating shaft 12 and the sliding surface 13 are not locally contacted with each other, it is possible to reduce the friction coefficient of the oil-impregnated bearing and obtain bearing characteristics with a high use limit.

The rotating shaft 12 is provided on the inner peripheral surface.
The sliding surface S is provided at two locations that are symmetrical in the circumferential direction about a point Z facing 180 ° to the side where a member for transmitting a force is arranged.
Since 1 · S2 is formed, when the rotary shaft 12 rotates in one direction and becomes a steady state, the rotary shaft 12 is opposed to one sliding surface S1 and in the opposite direction. When it is rotated, it is opposed to the other sliding surface S2.

As a result, even when the center axis of the rotary shaft 12 is displaced when the rotary shaft 12 is rotated in both forward and reverse directions, the rotary shaft 12 can be reliably moved by the sliding surface S1 of the bearing body 11.
・ It will be opposed to S2. Therefore, in combination with the smooth supply of the lubricating oil described above, an oil-impregnated bearing having a small friction coefficient can be obtained.

Furthermore, when molding the green compact, the sliding surface S1
Since the hole in the portion to be S2 is crushed, the plastic deformation of the sliding surface S1, S2 is smoothly performed, and the hole is reliably crushed, and the sliding surface S1, S2 is There is an advantage that a sintered oil-impregnated bearing can be manufactured by a process exactly the same as the conventional process, without newly providing a process of crushing the holes.

In the above embodiment, the roughened portion 19 is formed on the core rod 17 by using the electric discharge machining, but the invention is not limited to this. For example, the roughened portion 19 may be formed by machining such as knurling. .

Further, in the above embodiment, the example in which the sliding surface is formed at two places has been described, but as shown in FIG. 2, it may be provided at three places (S1, S2, S3) or more places. It's okay.

With this structure, a sliding surface is also formed in the contact portion with the bearing body 11 when the rotating shaft 12 is in a stopped state, so that the rotating shaft 12 and the bearing hole 13 at the initial stage of start-up. The friction with can be reduced.

Further, in the example shown in FIG. 2, a plurality of oil supply parts P1, P2 are formed between the respective sliding surfaces S1, S2, S3. It is also possible to match the point Z facing 180 ° to the side where the member for transmitting the force to the rotary shaft 12 is arranged on the inner peripheral surface.

By doing so, the bearing body 11
The degree of freedom of alignment with respect to the rotary shaft 12 is increased.

[0029]

As described above, according to the sintered oil-impregnated bearing of the present invention, within the inner peripheral surface of the bearing hole, the above-mentioned inner peripheral surface is within a range of approximately half around the side where the rotary shaft slides. At the side on which the member for transmitting force to the rotating shaft is arranged at 180 °
It is characterized in that a plurality of holes that are symmetrical in the circumferential direction with respect to the opposite point are crushed in the axial direction of the bearing body during the powder compaction of the bearing body. Produce an effect.

The bearing body is easily plastically deformed, the holes are surely crushed, and the lubricating oil on the sliding surface formed after sintering does not leak. Therefore, a strong oil film with no hydraulic pressure drop is formed on the sliding surfaces, and sufficient lubricating oil is provided on the sliding surfaces and the rotating shaft between the sliding surfaces or from other holes on the inner peripheral surface of the bearing hole. Is supplied to. Therefore, since the rotary shaft and the sliding surface are not brought into local contact with each other, the friction coefficient of the oil-impregnated bearing can be reduced, and the bearing characteristics with high usage limit can be obtained.

Further, when the green compact is molded, the pores of the sliding surface are crushed, so that the plastic deformation of the sliding surface is smoothed and the crushing of the pores is ensured. In addition, it is not necessary to newly provide the step of crushing the holes on the sliding surface after sintering, and the sintered oil-impregnated bearing can be manufactured by the same step as the conventional one.

Further, since the inner peripheral surface is formed by crushing holes in a plurality of surfaces symmetrical with respect to a point opposite to the side on which the member for transmitting force to the rotary shaft is arranged by 180 °. Even if the position of the rotary shaft is displaced due to normal or reverse rotation of the rotary shaft, the sliding surface should be positioned corresponding to the position, and holes should be positioned on both sides of this sliding surface. As a result, the lubricating oil supply conditions are made uniform.

[Brief description of drawings]

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

FIG. 2 is a front view of a sintered oil-impregnated bearing according to another embodiment of the present invention.

FIG. 3 is a vertical sectional view of a conventional oil-impregnated sintered bearing.

FIG. 4 is a sectional view taken along the line AA in FIG.

FIG. 5 is a cross-sectional view of a main part of a die set for explaining a method for manufacturing a sintered oil-impregnated bearing according to the present invention.

[Explanation of symbols]

10 Sintered oil-impregnated bearing 11 Bearing main body 12 Rotating shaft S1, S2, S3 Sliding surface P1, P2 Oil supply part Z A point facing 180 ° to the side where the member transmitting force to the rotating shaft is arranged on the peripheral surface

Front Page Continuation (72) Inventor Satoshi Murayama 1 3-3, Kogane-cho, Niigata City, Niigata Prefecture Mitsubishi Material Co., Ltd. Niigata Plant (72) Inventor Takeshi Tanaka 390 Umeda, Kosai City, Shizuoka Asmo Stock Company In-house (72) Invention Person Daisuke Oba 390 Umeda, Kosai City, Shizuoka Asmo Stock Association In-house

Claims (1)

[Claims] 1. A sintered oil-impregnated bearing in which a bearing main body made of a porous sintered alloy is formed with a bearing hole through which a rotary shaft is inserted. Within a range of a substantially half circumference on the side where the shaft slides, there are a plurality of locations that are symmetrical in the circumferential direction around the point on the inner peripheral surface where the member that transmits the force to the rotary shaft is 180 ° opposite. A sintered oil-impregnated bearing, characterized in that the holes are crushed in the axial direction of the bearing body when the bearing body is compacted.