JPH08177861A - Oil retaining bearing - Google Patents

Abstract

PURPOSE: To increase the durability of an oil retaining bearing by forming a groove in a bearing end surface so as to eliminate oil leakage, forming a bearing with two members of an inner part and an outer part, and impregnating the two members with lubricating oils different in quality from each other. CONSTITUTION: An oil retaining bearing is an annular compact formed type sintered metal body. The compact formed type sintered metal body comprises an inner part 2 at the center of which a bearing part is formed and an outer part 4 connected to the outer periphery side of the inner part concentrically to it. Also a V-shaped groove part 5 is formed in a joint end surface between both of them, or lubricating oils different in quality from each other are retained in the inner and outer parts. Thus an ideal sintered oil retaining bearing 1 which, when the temperature of the oil retaining bearing is increased, prevents leakage of lubricating oil, perform running-in immediately, reduce coefficient of friction after running-in, is free from wow can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing impregnated with lubricating oil, which comprises an annular powder-compacted sintered metal body having a bearing portion formed in the center thereof. The inner portion having the bearing portion formed at the center and the outer portion fitted around the inner portion are coupled to each other, and a V-shaped groove is formed on the coupling end surfaces of both members, so that the impregnated lubricating oil is unnecessary. The object is to prevent leakage and improve the durability of the oil-impregnated bearing by impregnating both members with different kinds of lubricating oil.

[0002]

2. Description of the Related Art The latest technology for effectively retaining a lubricating oil component impregnated in a powder compacted sintered metal body in the sintered metal body has been developed by the present applicant. A "bearing made of sintered metal" (Jun. 6-29536) is known. This consists of an outer powder-compacted sintered metal body with a bearing on one side of the annular inner powder-compacted sintered metal body with bearings and a projecting joint on the other side. The above-mentioned joining parts are joined to the other sintered metal part body, and a lubricating component storage part is formed between both annular part bodies.

Further, by forming a groove having a V-shaped cross section on the end surface of a sintered oil-impregnated bearing made of a single member, the lubrication characteristics against thrust load are improved, or the same shape which is almost indistinguishable from the appearance is formed. In addition, there is also known one that is easily distinguished from another bearing impregnated with a different lubricating oil.

[0004]

However, in the case of the above-mentioned sintered oil-impregnated bearing according to the prior art, when heat is generated due to friction with the rotary shaft, the rotary shaft of the metal and the powder-molded sintered metal part are produced. In some cases, a part of the lubricating oil leaks out from the bearing due to the difference in the thermal expansion coefficient between the bearing and the lubricating oil impregnated in the bearing. Further, particularly when the rotating shaft rotates at a high speed, air is entrained by the oil pressure caused by the sliding of the inner peripheral surface of the bearing portion and pushed into the oil hole from the inner peripheral surface of the bearing, so that the lubricating oil in the oil hole Will be pushed out.

The lubricating oil that has been pushed out and leaked loses its hydraulic pressure due to the rotation stop of the rotating shaft, and is absorbed again from the inner peripheral surface of the bearing portion due to the decrease in the bearing temperature. Is lost by adhering to the rotating shaft and the housing, resulting in a so-called oil leak. This oil leakage has problems such as deterioration of performance such as deterioration of bearing durability and adverse effects on peripheral equipment due to contamination of the surroundings.

Further, the porous structure which is the characteristic of the oil-impregnated bearing is
While it has the advantage of being able to supply the lubricating oil to the sliding surface automatically, stably and continuously, it has the drawback that the lubricating oil easily escapes from the oil hole due to the hydraulic pressure generated by the rotation of the rotary shaft. For this reason, it is usual to use a so-called mixed lubrication state in which light metal contact is intermittently repeated between the rotating shaft and the bearing portion not only in the familiar period at the initial stage of start-up but also in the stationary period.

However, when the oil-impregnated bearing is used in an audio device, even a slight sliding noise is avoided, so that the oil holes on the inner surface of the bearing portion are reduced to suppress the escape of hydraulic pressure and the state close to fluid lubrication. However, if the number of oil holes on the inner surface of the bearing is reduced from the beginning on the other hand, the predetermined oil film thickness will be reached immediately after the rotary shaft is started. And the so-called familiarity for smoothing fine irregularities on the surface of the bearing is insufficient, and even after entering the stationary period from the initial stage of shaft rotation, the above-mentioned mild metal contact is repeated intermittently, resulting in a current value The occurrence of so-called wow caused by fluctuation is regarded as a problem, and it cannot be said that it is very good.

In this case, it has been understood that it is possible to bring the state to an ideal state to some extent by carrying out a leveling operation of the actual machine for a certain period of time or gradually increasing the load during the performance test of the oil-impregnated bearing. It is not practical to go through such a process because it not only requires a lot of trouble and time, but also causes a significant cost increase.

Further, in the case of a sintered oil-impregnated bearing having a groove having a V-shaped cross section formed on the end surface of the sintered oil-impregnated bearing, a V-shaped groove is formed at the tip of the punch surface at the time of compacting as a forming means. Is formed and is pressed against the end surface of the sintered oil-impregnated bearing to form a concave groove having a V-shaped cross section. However, due to restrictions on the punch strength, the groove is too deep and has an acute angle. I can't. Therefore, since the angle of the V-shaped groove on the end face obtained by this method is within the range of 45 to 60 degrees at most, it is almost impossible to hold the lubricating oil oozing out from the bearing in this groove. Is.

[0010]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art, and firstly, eliminates oil leakage from the bearing portion when heat is generated due to friction with the rotating shaft, and improves durability of the oil-impregnated bearing. Secondly, an ideal sintered oil-impregnated bearing is provided in which the so-called familiarity is promptly performed with slight wear immediately after the start of the rotating shaft, the coefficient of friction after familiarization is low, and wow is not generated. Specifically, it is a ring-shaped powder compacted sintered metal body, wherein the powder compacted sintered metal body comprises an inner portion having a bearing portion formed in the center and an outer peripheral surface side of the inner portion. In addition, the present invention relates to an oil-impregnated bearing comprising an outer portion concentrically connected to the outer portion, and a groove portion having a V-shaped cross section formed on a joint end surface of the inner portion and the outer portion.

The present invention also provides a ring-shaped powder compacted sintered metal body, wherein the powder compacted sintered metal body has an inner portion having a bearing portion formed at the center and an outer peripheral surface side of the inner portion. The present invention relates to an oil-impregnated bearing comprising an outer portion concentrically coupled to the outer portion, and wherein the inner portion and the outer portion are impregnated with different lubricating oils.

[0012]

When the groove portion having a V-shaped cross section is formed on the joint end surface between the inner portion and the outer portion of the green compact sintered metal body, the bearing portion generates heat as the rotary shaft is driven, and the oil-impregnated bearing is formed. When the temperature rises, the amount of the lubricating oil impregnated in the bearing that oozes out in the direction of the end surface of the bearing that is parallel to the rotating shaft is retained in the V-shaped groove. Further, when the driving of the rotary shaft is stopped, it is absorbed again in the bearing.

When the inner part and the outer part of the compacted and sintered metal body are impregnated with different kinds of lubricating oil, low-viscosity lubricating oil from the inner part is received from the inner part at the beginning of rotation of the rotating shaft. It is supplied to the inner surface, and mild metal contact is intermittently repeated between the rotating shaft and the bearing part, so-called "familiar" is quickly performed, and when it enters the stationary phase as it is, high viscosity from the outer part Is supplied to the inner portion, mixed with the low-viscosity lubricating oil in the inner portion to become a lubricating oil having a desirable viscosity originally intended, and sequentially supplied to the bearing portion.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The concrete contents of the present invention will be described below with reference to the drawings. First Embodiment of the present invention for preventing oil leakage is shown in FIG. 1 and FIG. In the figure, 1 is a green compact sintered metal body,
An oil-impregnated bearing formed by concentrically connecting two sintered bodies, each of which is composed of an inner portion 2 and an outer portion 4 concentrically fitted to the inner portion 2, is shown. Inner part 2
The bearing portion 3 is formed at the center of the bearing, and the outer portion 4 is joined to the outer peripheral surface thereof by a method such as press fitting or two member integrated sizing. Further, a groove portion 5 having a V-shaped cross section is formed on a joint end surface of the inner portion 2 and the outer portion 4.

Regarding the size of the groove portion 5, the required volume is taken into consideration based on the expected temperature rise of the bearing, the oil content, and the like. For example, the coefficient of thermal expansion of iron = 13 × 10 minus 6th lubricating oil. Coefficient of thermal expansion = approximately 240 × 10 minus 6 power can be obtained by the above calculation formula. In this case, when the rotary shaft rotates at high speed, it is necessary to take into consideration the amount of air entrained from the bearing portion 3.

Further, the inner portion 2 is press-fitted into the outer portion from the side surface of the outer portion 4. Prior to the press-fitting, the inner portion 2 is provided with a relatively low-viscosity lubricating oil and the outer portion 4 is relatively high in viscosity. A lubricating oil of viscosity is impregnated respectively. In this case, the above-mentioned two kinds of lubricating oils are best if they are of the same brand and have different viscosities, because there is no adverse effect due to the mixing of the two. Further, the two lubricating oils must be selected in consideration of the oil-impregnated volumes of the two bearings, the inner portion 2 and the outer portion 4, so that the viscosity after mixing is optimum for the steady operation of the oil-impregnated bearings. But there is
The above-mentioned two types of lubricating oils are more effective when the difference in viscosity between them is large.

Further, FIG. 3 not only promotes "familiarity" in the initial stage of starting the rotating shaft, and also obtains an ideal lubricating effect by the lubricating oil in the stationary phase, and also automatically aligns the rotating shaft. A second embodiment of the present invention is shown which has the characteristics. This is basically composed of two members, an inner part 12 and an outer part 15 made of a powder compacted sintered metal body as in the first embodiment described above.
The inner portion 12 has a bearing portion 13 at the center, and also has a spherical portion 14 formed in a spherical shape on the outer peripheral surface thereof so that the central portion thereof projects outward. Further, the outer portion 15 is formed with a recess 16 continuous in the circumferential direction on the inner peripheral surface side thereof. The inner portion 12 is press-fitted from the side surface of the outer portion 15 so as to be settled in the recessed portion 16. Prior to the press-fitting, a relatively low-viscosity lubricating oil is used for the inner portion 12 and the outer portion 15 is compared. The high-viscosity lubricating oil is impregnated respectively.

Regarding the method for impregnating the powder compacted sintered metal body with the lubricating oil in this case, for example, each member can be impregnated with the lubricating oil by a method such as a vacuum method or a heating method.

As an example of the method of molding the outer portion 15 in this case, both ends are made thick, and one end side thereof is projected in the inner diameter direction and the other end side is projected in the outer diameter direction which is the opposite side. Insert the cylindrical pressed powder metal body into the drawing die, with the large diameter side protruding in the outer diameter direction at the beginning, and further downsize by the upper punch to make the inner diameter of the protruding portion in the outer diameter direction. In this way, both ends can be formed so as to project toward the inner diameter side. Further, in this case, when the protruding portion 15a of the outer portion 15 is large and it is difficult to press-fit the spherical inner portion 12, it is necessary to insert the inner portion 12 into the outer portion 15 in advance as shown in FIG. Lower die 1 having a tapered portion 18a at the upper opening edge from
8, the core 20 is fitted vertically on the lower punch 19, and the upper punch 21 having the core hole 22 corresponding to the core 20 formed at the center is pressed down and sized to the outer shape on the other end side. It is also possible to make the direction protrusion 15a reversely protrude toward the inner diameter side.

With this structure, the gap 16 is formed between the inner portion 12 and the outer portion 15, and sufficient lubricating oil is stored in the gap 16 and is formed on the outer peripheral surface of the inner portion 12. The V-shaped groove portion 17 is formed between the spherical surface and the portion of the inner peripheral surface of the outer portion 15 that is closer to the side surface.
When the temperature of the oil-impregnated bearing rises as a result, the amount of the lubricating oil impregnated in the bearing exuding in the direction of the end surface of the bearing which is parallel to the rotating shaft is V-shaped groove portion 17 described above. Retained within.

Further, in this case, when the inner portion 12 and the outer portion 15 made of the powder compacted sintered metal body are impregnated with different lubricating oils from each other, the initial rotation of the rotating shaft (not shown) is performed. In addition, low-viscosity lubricating oil is supplied from the inner portion 12 to the inner surface of the bearing portion 13, and light metal contact is intermittently repeated between the rotary shaft and the bearing portion 13, so-called "familiarization" is rapidly performed. At the start of the stationary phase, a high-viscosity lubricating oil is supplied from the outer portion 15 into the inner portion 12, and mixed with the low-viscosity lubricating oil in the inner portion 12 to obtain a lubricating oil having a desirable viscosity originally intended. Then, they are sequentially supplied to the bearing unit 13.

That is, in the case of the conventional oil-impregnated bearing with a single member, the oil holes are reduced due to the initial running-in, and the oil film is slightly thickened as a result, but the difference between the oil film thickness during the initial running-in and the steady time is small. Therefore, even in the stationary phase, a slight change in the oil film thickness causes contact between the rotating shaft and the surface protrusion of the bearing portion, which causes so-called wow.However, in the case of using the oil-impregnated bearing of the present invention described above, At the time of initial startup of the shaft, low-viscosity lubricating oil is supplied to the sliding surface of the bearing portion 13. Since the oil film of the low-viscosity lubricating oil is thin, most of the protrusions on the sliding surface of the rotating shaft and the bearing contact with each other and are smoothed. On the other hand, the lubricating oil impregnated in the inner portion 12 also circulates in the bearing by the pumping action of the oil-impregnated bearing immediately after the start of the rotary shaft, and the high-viscosity lubricating oil impregnated in the outer portion 15 on the outer side gradually increases. 12
The lubricant is gradually mixed into the lubricating oil impregnated in the above, and eventually the entire bearing is impregnated with a uniform mixed oil of two kinds of lubricating oil.

Since the viscosity of the mixed oil in this case is higher than that of the low-viscosity lubricating oil discharged from the inner portion 12 in the initial "familiarization", the thickness of the oil film under the same operating conditions is also It becomes thicker than at the time of initial familiarization, and even if the thickness of the oil film fluctuates somewhat due to equipment vibration,
The protrusions lower than the oil film thickness do not come into contact with each other.

When the oil-impregnated bearing 11 is attached to the rotary shaft, if the axial directions of the two do not completely coincide with each other, the inner portion 12 is fixed with respect to the fixed outer portion 15.
The spherical surface portion 14 on the outer peripheral surface side freely slides, whereby the axial center direction of the inner portion 12 can be freely changed according to the inclination of the rotary shaft, and the contact surface between the rotary shaft and the oil-impregnated bearing is always Make parallel and even contact.

[0025]

As described above, according to the present invention, the cross-section V is formed on the connecting end face of the inner portion and the outer portion of the powder compact sintered metal body.
In order to form a V-shaped groove, a V-shaped convex portion is formed at the tip of the punch surface at the time of powder compacting as in the past, and this is pressed against the end surface of the sintered oil-impregnated bearing to form a V-shaped cross section. As compared with the case where a groove having a large depth and an acute angle cannot be formed due to the restriction on the punch strength,
It becomes possible to form a V-shaped groove with a more acute angle. Therefore, when the bearing part generates heat as the rotary shaft is driven and the temperature of the oil-impregnated bearing rises, the lubricating oil impregnated in the bearing becomes parallel to the rotary shaft. The portion that oozes out in the direction of the end face of the bearing is held in the V-shaped groove described above and is absorbed again in the bearing when the drive of the rotary shaft is stopped, so that so-called oil leakage can be prevented. In addition, it is possible to eliminate the adverse effects of stains on peripheral equipment and significantly improve the durability of the oil-impregnated bearing.

When the inner and outer parts of the compacted and sintered metal body are impregnated with different kinds of lubricating oil, low-viscosity lubricating oil is received from the inner part at the beginning of rotation of the rotary shaft. It is supplied to the inner surface, and mild metal contact is intermittently repeated between the rotating shaft and the bearing part, so-called "familiar" is quickly performed, and when it enters the stationary phase as it is, high viscosity from the outer part Is supplied to the inner part and mixed with the low-viscosity lubricating oil in the inner part to form the desired desired viscosity of lubricating oil, which is sequentially supplied to the bearing part. It is possible to obtain an ideal sintered oil-impregnated bearing in which so-called familiarization is rapidly performed with abrasion, and the friction coefficient after familiarization is low and wow is not generated.

Further, in an oil-impregnated bearing comprising an inner part and an outer part concentrically coupled to the outer peripheral surface side of the inner part, the inner part is spherical and a space is provided between the inner part and the outer part. In the case where the inner part is formed, the spherical part on the outer peripheral surface side of the inner part can freely slide with respect to the fixed outer part. The shaft center direction can be changed freely, the contact surfaces of the rotary shaft and the oil-impregnated bearing can always contact in parallel and evenly, and the durability of the oil-impregnated bearing can be remarkably improved. It is possible to eliminate heat generation and seizure due to the one-sided contact phenomenon, and further prevent a problem such as uneven wear.

[Brief description of drawings]

FIG. 1 is an enlarged side view of an oil-impregnated bearing that is a first embodiment of the present invention.

FIG. 2 is a sectional view of the oil-impregnated bearing shown in FIG.

FIG. 3 is an enlarged sectional view of an oil-impregnated bearing, which is a second embodiment of the present invention.

[Explanation of symbols]

 1 Oil-impregnated bearing 2 Inner part 3 Bearing part 4 Outer part 5 Groove part 11 Oil-impregnated bearing 12 Inner part 13 Bearing part 14 Spherical part 15 Outer part 16 Clearance 17 Groove part

Claims (5)

[Claims] 1. A ring-shaped powder compacted sintered metal body, wherein the powder compacted sintered metal body has an inner portion having a bearing portion formed in the center, and an inner portion on the outer peripheral surface side of the inner portion. An oil-impregnated bearing comprising a concentrically joined outer portion, and a groove portion having a V-shaped cross section formed on a joint end surface between the inner portion and the outer portion. 2. An annular powder-compacted sintered metal body, wherein the powder-compacted sintered metal body has an inner portion having a bearing portion formed at the center thereof, and an inner portion on the outer peripheral surface side of the inner portion. An oil-impregnated bearing comprising an outer portion concentrically connected to each other, wherein the inner portion and the outer portion are impregnated with different kinds of lubricating oil. 3. The oil-impregnated bearing according to claim 2, wherein the inner portion is impregnated with a low-viscosity lubricating oil, and the outer portion is impregnated with a high-viscosity lubricating oil. 4. The oil-impregnated bearing according to claim 1, wherein the inner portion is spherical and a void is formed between the inner portion and the outer portion. 5. The oil-impregnated bearing according to claim 2, wherein the inner portion has a spherical shape and a gap is formed between the inner portion and the outer portion.