JPS61165019A - Sintered oil-impregnated bearing - Google Patents

Abstract

PURPOSE:To prevent burrs from arising in the crossing sections of large and small diameter sections, by setting the inner diameter of each large diameter section to a value equal to the inner diameter of the small diameter sections at both end thereof, and by gradually increasing the inner diameter of the large diameter section toward the center section thereof. CONSTITUTION:Wall surfaces defining relieves 101 are formed in an arcuate surface so that the diameter of each relief is set to be equal to that of small diameter sections defening a bearing hole 91 while it is gradually increased from each end to the center section thereof. Accordingly, the angle between the wall surface defining each relief 101 and each small diameter section of the bearing hole 91 becomes acute. Therefore, it is possible to effectively prevent burrs from arising at each of crossing sections of large and small diameter sections in the bearing hole 91.

Description

[Detailed Description of the Invention] [Further Field of Application] The present invention further develops the contents of the previously filed Japanese Patent Application No. 187445/1982 and relates to a running sintered oil-impregnated bearing [Prior Art] Powder metallurgy method There are various applications and usage methods for this type of oil-impregnated bearing manufactured by the company, but there are cases where two of the same bearing are used in parallel.

An example is the coreless motor shown in Fig. 1.2 is attached to the resin support 5, and the resin support 5 is attached to the iron core 6.

By the way, conventionally, oil-impregnated bearings 2 have been simply cylindrical with a uniform cross-sectional shape in the thin direction.

However, it goes without saying that there will be variations in the positioning of each bearing.

Since there are variations in the size of 1.2, two oil-impregnated bearings 1. It is difficult to mount B without eccentricity to the motor shaft 4, which inevitably causes problems such as noise and shaft galling.

Therefore, the applicant of this application made the inner diameter of the bearing smaller at both ends of the bearing and larger at the center in the axial direction.
We first proposed a sintered oil-impregnated bearing that allowed one bearing to perform the same functions as two bearings (patent application 1983-1999).
(See No. 187445).

The oil-impregnated bearing 7 according to the future proposal is 39, for example, the above-mentioned 7
Used in place of bearings 1 and 2 in Hiko-less motors.
(Fig. 2), although the oil-impregnated bearing 7 is integral as a whole, both end portions 7a+7b are spaced apart from each other.
The bearings perform the same function as the independent conventional bearings [, 2].

In that case, in order to effectively perform such a function, it is necessary to have a central portion 7c with a large diameter and both end portions 7a+ with a small diameter.
It is necessary to set the diameter difference between 7b and 7b to 2 μm or more.

By the way, in the oil-impregnated bearing 7 according to the above proposal, the bearing length is, for example, about φ to 7 mm, and moreover, it is assumed that there is contact at two places (that is, support at two places). Therefore, in the central part of the bearing, there were only 1 places with a large diameter [the pinnacle of conventional technology].
Some of them exceeded 0,000, and the problem of defects due to bending of the bearing hole was noticeable. The inventors of this application have also made various studies regarding the bending of the bearing hole in the case where the bearing length of the crosspiece is long, and in order to solve the problem of bending, the above-mentioned concept of the previous proposal was applied to the crossbeam. We found that a particular method was effective.

[Purpose of the invention]

This invention solves the problem of curvature of the bearing hole based on this knowledge.
The present invention provides a large FR9 sintered oil-impregnated bearing with two or more locations.

[Implementation %D] Hereinafter, the content of the present invention will be explained in detail with reference to the attached FIGS. 3 to 6.

In the sintered oil-impregnated bearing 81.82 of the present invention, as shown in FIG.
The feature is that a plurality of 02 are provided.

Therefore, in the axial direction of each of these sintered oil-impregnated bearings 81, 82, there are locations with large bearing inner diameters (i.e., portions corresponding to reliefs 101° and 102) at multiple locations spaced apart from each other. These serve to prevent the bearing holes IJI and 92 from bending. The mechanism of this anti-bending effect of the bearing holes 91 and 92 is not clear, but since these sintered oil-impregnated bearings 81 and 82 are manufactured by powder metallurgy, the I! The relief 10 L, 102
It can be considered that a shape with

This point will become clearer in future explanations. Note that the number of reliefs to t , 102 is plural, and it is desirable to increase the number as the bearing length is longer.

By the way, if only the function of preventing the bearing holes 91, 92 from bending is obtained, there is no restriction on the shape of the reliefs 101, 102, and the mural defining the reliefs 101, 102 may have a U-shaped cross section. However, if the wall surface is made into a U-shape, the angles between the side wall surfaces of the relief lots and toz and the small diameter portions b Q fr of the bearing holes 91 and 92 will be at right angles, making it easy for cracks to occur at their intersections. If burr occurs, the shaft inserted into the bearing hole 91.92 may be damaged by the burr, or burr may enter between the bearing hole 91.92 and the shaft, causing malfunction. be. Furthermore, if the angle between the side wall surface and the small diameter portion of the bearing hole 91.92 is a right angle, when inserting the shaft into the bearing hole 91.92, even if the axis line between the bearing hole 91.92 and the shaft is very small, If it is tilted, the end of the shaft will come into contact with the side wall surface of the relief lot 102, making it difficult to insert the shaft smoothly.

In this respect, in this sintered oil-impregnated bearing, the clearance is 101°1.
02), the diameter of the relief is the same as the small diameter portion of the bearing hole 91, 92 at both ends, and gradually increases from both ends toward the center. Therefore, the angle formed between the wall surface defining the relief 101, 102 and the small diameter portion of the bearing hole 91, 92 is an obtuse angle.

Therefore, it is possible to prevent the occurrence of a flash at the intersection thereof, and it is possible to solve the various problems described above due to the occurrence of a flash. In addition, the diameter of the wall surface defining the reliefs 101 and 102 gradually becomes smaller as it goes from the center to the ends, and becomes the same diameter as the small diameter portion of the bearing holes 91 and 92 at the ends. Even if the axes of the bearing holes 91 and 92 and the shaft inserted therein are inclined to each other,
The shaft is guided into the small diameter portion of the bearing hole SJ1.92 by the walls defining the reliefs 101 and 102, thus allowing smooth insertion of the shaft.

Furthermore, among the bearings shown in FIG. 3 [al, fb), one bearing 81 has a ring-shaped groove 11 in the outer local part of the bearing corresponding to the relief 101 on the inner peripheral side, and the other bearing 82 has a ring-shaped groove 11. There is no corresponding groove. This depends on how the grooves 11a+flb, llc are provided on the outer peripheral surface of the sintered body as described below.

Next, we will explain a method suitable for manufacturing the sintered oil-impregnated bearing with the above structure. Sintered parts are usually manufactured through a powder compaction process, a sintering process, and a repressing process after sintering. Here, the sintered body 12 after the sintering process has a ring-shaped groove 11a on the outer circumferential surface of the central portion in the axial direction (corresponding to the location where the relief ioi, 102 is provided) as shown in FIG.

One having LLb and ILc is formed in advance. These *Lla, lLb, and Llc can be formed by cutting or by changing the shape of the die used during powder compaction. The sizes and shapes of these grooves 11a and 1lb11c are based on the clearance LOL of the bearing hole 91°92, 102
It can be selected appropriately depending on the size etc.

Then, such a sintered body 12 is pressed again in the usual manner, that is, as shown in FIG. Upper punch 14. By using the lower punch 15 and the core rod 16, pressure is compressed in the axial direction. Then, the outer diameter portion of the sintered body 12 and the grooves 11a and Llb.

In the Llc portion, the meat moves outward so as to follow the shape of the die 18. On the other hand, the bearing hole portion has a groove 11a.

The bearings 81 and 82 as described above and shown in FIG. The shape is obtained.

Next, the effects of this invention will be clarified based on an actual prototype example.

There are three types of sintered body L2 as shown in FIGS. 6(a) to (C), namely (al: one in which two grooves 11a are concentrated in the center of the outer circumferential surface, and (b): ( (C): The number of grooves 11b is ψ, and the width of the groove ILa is larger than that of (a), and the valley grooves ILa are distributed over the entire outer peripheral surface, and the outer peripheral surface is the same as that of (b). After repressurizing and correcting the sample using the method described above, the variation width of each prototype was determined using a predetermined plug gauge, and the results shown in the following table were obtained.

Since the area within the width is about 10%, it is clear that the present invention has an effect of preventing bending of the bearing hole. In addition, the bearing inner diameter of the prototype is φt■, the bearing length is approximately 3 hiro, and the depth of the groove LLa is Q r wm af31. It is.

〔Effect of the invention〕

As explained above, according to the sintered oil-impregnated bearing of the present invention, the inner diameter of the bearing is increased at two or more locations that are mutually adjacent in the axial direction, and the inner diameter of the large diameter portion is changed to the small diameter portion at both ends. The diameter is the same as that of the bearing hole, and the diameter is gradually increased from both ends toward the center, which prevents the bearing hole from bending and also prevents the intersection of the large and small diameter portions of the bearing hole. It is possible to prevent this from occurring, and also to be able to smoothly insert the shaft into the bearing hole.

[Brief explanation of drawings]

Figure 3 shows an example of application of a conventional bearing of this type, Figure 2 shows an example of application of a bearing according to the previous proposal, and Figures 3 (a) and (b) are the same according to the present invention. A cross-sectional view showing an embodiment of a sintered oil-impregnated bearing, FIG. 81, 82... ... Sintered oil-impregnated bearing according to this invention,
91.92...Bearing hole, 101,102...
...Escape, ll, lla, llb tllc--
--- Groove on outer peripheral surface, 12...Sintered body. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) The inner diameter of the sintered oil-impregnated bearing is increased at two or more locations separated from each other in the axial direction, and the inner diameter of the large diameter portion is the same as the small diameter portion at both ends, and the inner diameter of the large diameter portion is made the same diameter as the small diameter portion at both ends, and 1. A sintered oil-impregnated bearing characterized in that the bearing gradually increases in size toward the bottom.