JPH06129431A - Sintered oil retaining bearing - Google Patents

Abstract

PURPOSE:To make the adequate supply of lubrication oil possible and form a firm oil firm in retention between both and retain smooth rotation over a long period by forming slide surfaces with an interval and width size of a specific shape. CONSTITUTION:In the case of a sintered oil-containing bearing 10 in which a bearing hole 23 into which a rotary shaft 12 is inserted, is formed at a bearing main body 11 formed of a porous sintered alloy, on the inner periphery surface of the bearing hole 13, slide surfaces 14 are formed by crushing the empty holes of the inner periphery surface at the time of the pressed powder formation of the bearing main body 11. These slide surfaces 14 are formed with the width of a 40 deg.-120 deg. angle around the axis of the bearing hole 13, and at the same time are formed at plural places with the interval of 2X(thetaf-10 deg.) (but thetaf is a load direction at a stationary time). Thus, a proper facing state between a slide surface and the rotary shaft is realized, and empty hole crushing at slide surfaces is carried out at the time of the pressed powder formation of the bearing main body, and by carrying out the plastic deformation of the inner periphery surface, the retainability of lubrication oil is improved.

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. 1, a sintered oil-impregnated bearing 1 of this type has a bearing body 2 made of a porous sintered alloy.
The rotary shaft 4 having a smaller diameter than that of the bearing hole 3 is inserted into the bearing hole 3 formed in the bearing hole 3 and is 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. The lubricating oil and the lubricating oil that oozes out due to expansion due to frictional heat form an oil film on the sliding surface 5 of the bearing hole 3, and the oil film rotatably supports the rotating shaft 4. .

[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 5 of the bearing hole 3 on which the rotary shaft 4 slides. Even if an oil film is formed, a part of the lubricating oil leaks from the holes to reduce the hydraulic pressure, and as a result, the rotating shaft 4 and the sliding surface 5 are locally brought into contact with each other. Thus, there is a drawback that the friction coefficient of the sintered oil-impregnated bearing 1 becomes large 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, since the sliding surface is formed by covering the bearing hole over approximately half of its circumference, the portion where the hole, which is the supply portion of the lubricating oil, is formed becomes small, and the sliding This is a problem that the amount of lubricating oil supplied to the surface is reduced, and the original lubricating effect of the sintered oil-impregnated bearing is halved.

[0009]

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 through which a rotary shaft is inserted is formed in a bearing body formed of a binding metal, a hole in the inner peripheral surface is formed in the inner peripheral surface of the bearing hole. Crushed during molding to form a sliding surface, and this sliding surface
The bearing hole is formed with a width of 40 ° to 120 ° around the axis, and is formed at a plurality of positions at intervals of 2 × (θf−10 °) (where θf is the load direction at rest). And

[0010]

In the sintered oil-impregnated bearing of the present invention, by forming the sliding surface with the above-described width dimension and spacing, the area of the hole portion is secured, and by the hole between the sliding surfaces, Lubricating oil is supplied to the sliding surface from a position close to the sliding surface, and the lubricating oil is sufficiently supplied to the sliding surface.

The two rotating shafts differ in that the shaft and the bearing are in contact with each other in the rotating direction. This is due to the following points.

First, when decelerating using a worm gear, the direction in which the gear is located is taken as the center line, the direction facing the gear is set to 0 °, and the direction in which the load is applied at rest is θf.
If so, θf is deviated in the axial rotation direction by the values shown below depending on the tooth angle pressure angle α of the worm gear, the lead angle λ, and the friction coefficient μ of the worm and the worm gear. In the case of both rotations, the load direction is determined at a position symmetrical with respect to the center line. θf = tan-1 {(cosα · sinλ + μcosλ)
/ Sinα}

Further, although fluid lubrication can be realized by crushing the holes, in order to ideally realize it, 3 ° in the forward direction from the point of 10 ° in the direction opposite to the rotational direction of the shaft with respect to θf.
It has been found that the points up to 0 ° are squashed, that is, at least 40 ° is required.

The second reason why the contact point between the shaft and the bearing changes is that the shaft is eccentric in the forward direction due to the rotation of the shaft, and this fact is generally well known. Although the structure of the present invention is a sintered oil-impregnated bearing, fluid lubrication can be realized by crushing the holes, and eccentricity of up to 80 ° is recognized at high speed rotation. The holes and the crushed area at this time are:
120 °, which is 80 ° added to 40 ° described above, is required.

Therefore, in order to bring out the effect of the present invention under any operating condition, the region where the holes are crushed is 40 ° to
It is desirable that the angle is 120 ° and the load direction θf is 10 ° from the rear end portion in the axial rotation direction of the region where the holes are crushed. Further, the region in which the holes for both rotary shafts are collapsed is symmetrical with respect to the center line, and the region in which the holes are not collapsed is 2 ×.
The positions are separated by (θf-10 °).

When the width of the sliding surface is less than the above range, the oil film holding property on the sliding surface is not sufficient,
Moreover, the effective opposing state of the sliding surface and the rotating shaft cannot be obtained,
Further, if it exceeds the above range, the sliding surface is too wide and the lubricating oil cannot be supplied smoothly, which is not preferable. Further, if the distance between the sliding surfaces is less than the above range, the lubricating oil is not sufficiently supplied to the sliding surfaces, and if it exceeds the above range, the sliding surface and the rotating shaft are effectively opposed to each other. Is not obtained and neither is preferable.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the sintered oil-impregnated bearing of the present invention will be described below with reference to FIG. Sintered oil-impregnated bearing 10 shown in FIG.
Is a bearing body 11 made of a porous sintered alloy.
In addition, a bearing hole 13 through which the rotary shaft 12 is inserted is formed. The bearing hole 13 is formed in the inner peripheral surface of the bearing hole 13 by crushing holes in the inner peripheral surface during powder compaction of the bearing body. The sliding surface 14 is formed at a plurality of positions at intervals in the circumferential direction, and the width W of the sliding surface 14 is within a range of 40 ° to 120 ° at an angle around the axis of the bearing hole. And the distance G is 2 × (θf−10 °); however, θf indicates the load direction at rest.

Each slide 14 of the sintered oil-impregnated bearing 10 has a roughened portion having a large surface roughness formed at a predetermined position on the surface of the core rod used in the normal powder compaction of the powder. When the powder compact is released from the powder compact after the powder compaction, the core rod plastically deforms a predetermined position of the bearing main body 11 to form the sliding surface 14 on the inner surface thereof.

As described above, the sliding surface 14 is formed at the time of powder compacting in that, when the sliding surface 14 is crushed at the time of powder compacting, the sliding surface 14 is smoothly plastically deformed and its pores are formed. Since there is an advantage that the sintered oil-impregnated bearing can be manufactured by exactly the same process as the conventional one, there is no need to newly provide a process of crushing the holes of the sliding surface 14, and is there.

The circumferential widths and intervals of the roughened portions of the core rod are set so as to correspond to the widths of the sliding surfaces 14 of the bearing holes 13 of the sintered oil-impregnated bearing to be manufactured within the above-mentioned range. It is set, and specifically, the width is set to allow for shrinkage due to sintering of the green compact to be molded.

Then, the green compact thus formed is taken out from the die and sintered at a predetermined temperature to obtain a sintered body. In this sintered body, the voids on the surface corresponding to each sliding surface 14 are crushed when it is a green compact, so the holes on each sliding surface 14 in the sintered body are crushed and each sliding surface is crushed. Bearing holes 13 other than 14
The holes 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 sliding surfaces 14 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 14 are smoothed.

On the other hand, in this embodiment, the width W of each sliding surface 14 and the gap G between each sliding surface 14 are set to the following values, and the total sliding surface 14 is 5: It is formed in the place. W = 65 ° G = 36 °

The sintered oil-impregnated bearing 10 according to the present embodiment thus formed is mounted on a predetermined bearing device, and the rotary shaft 12 is inserted while being impregnated with lubricating oil.
2 was rotated at 4000 rpm while applying a downward load of 20 kg in FIG.
Smooth rotation was maintained even after 000 hours.

For comparison, four sintered oil-impregnated bearings each having one of the above ranges removed were manufactured and tested under the same conditions. As a result, in any case, within the above elapsed time. A large increase in frictional resistance was observed.

Therefore, according to the sintered oil-impregnated bearing 10 of the present invention, it is possible to realize a proper opposed state between the sliding surface 14 and the rotary shaft 12 and also to supply an appropriate lubricating oil, and for a long period of time. Therefore, smooth rotation can be maintained.

Further, by crushing the holes of the sliding surface 14 at the time of powder compaction of the bearing body 11, the inner peripheral surface of the bearing body 11 is surely deformed by plastic deformation to improve the retaining property of the lubricating oil. To be

The above embodiment is an example, and various modifications can be made based on design requirements and the like. For example, although the example in which the sliding surface is formed at two locations has been described in the above embodiment, the number of installations can be changed appropriately.

[0029]

As described above, the sintered oil-impregnated bearing according to the present invention is a sintered body having a bearing body formed of a porous sintered alloy and a bearing hole through which a rotary shaft is inserted. In an oil-impregnated bearing, the inner peripheral surface of the bearing hole is crushed at the time of powder compacting of the bearing body to form a sliding surface on the inner peripheral surface of the bearing hole. It is formed with a width of 40 ° to 120 ° at the surrounding angle and 2 × (θ
It is characterized in that it is formed at a plurality of positions at intervals of f-10 ° (where θf is the load direction at rest), and has the following excellent effects.

A proper sliding surface and a rotating shaft are made to face each other, and a suitable lubricating oil can be supplied to form and hold a strong oil film between them to maintain smooth rotation for a long period of time. It is possible to provide a sintered oil-impregnated bearing that can be manufactured.

Further, by crushing the holes on the sliding surface at the time of powder compaction of the bearing body, the inner peripheral surface of the bearing body is surely deformed by plastic deformation, and the holes are surely crushed. It is possible to significantly improve the retention of the lubricating oil.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an example of a conventional sintered oil-impregnated bearing.

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

[Explanation of Codes] 10 Sintered oil-impregnated bearing 11 Bearing body 12 Rotating shaft 13 Bearing hole 14 Sliding surface W Sliding surface width G Spacing between sliding surfaces

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Satoshi Murayama 1 No. 3 Kogane-cho, Niigata City, Niigata Prefecture Mitsubishi Material Co., Ltd. Niigata Plant (72) Inventor Takeshi Tanaka 390 Umeda, Kosai City, Shizuoka In-house ( 72) Inventor, 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 into which a rotary shaft is inserted, the inner peripheral surface of the bearing hole having an inner peripheral surface thereof. The surface holes are crushed during the powder compaction of the bearing body to form a sliding surface, and the sliding surface is formed with a width of 40 ° to 120 ° at an angle around the axis of the bearing hole, and 2 x (θ
A sintered oil-impregnated bearing characterized in that it is formed at a plurality of locations at intervals of f-10 °). ; However, θf is the load direction at rest