JP2001050277A - Manufacture of bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a bearing of two-point support structure where sintered body is incorporated into a housing, efficiently in a relatively simple manner to give appreciable bearing performance. SOLUTION: This bearing manufacturing method has a positioning step of positioning a housing 21 in a forming hole 30, and a press-fitting step of press-fitting a raw material 1A to form a bearing body 10A in the housing 21 while a core rod 32 of a uniform outside diameter is kept passed through the raw material 1A. The press-fitting step bonds the diametrally external surface of the raw material 1A under compression to the diametrally internal surface of the housing 21, and presses both axial ends of the diametrally internal surface of the raw material 1A against the core rod 32 to form shaft supporting surface 12 with an intermediate recess 13 in between.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing suitable for use in supporting a shaft rotating at a relatively high speed, such as a drive shaft of a spindle motor built in precision equipment, with high precision. The present invention relates to a method of manufacturing a bearing of a type in which a bearing body having a middle relief portion that does not contact a rotating shaft is incorporated in a housing. The bearing body is formed by molding a material made of a sintered body or a porous body obtained by sizing the sintered body, is impregnated with lubricating oil, and is suitably used as a sintered oil-impregnated bearing.

[0002]

2. Description of the Related Art In a sintered oil-impregnated bearing, the lubricating oil impregnated in a sintered body seeps into an inner diameter surface, and an oil film is formed between the inner diameter surface and a rotating shaft, thereby reducing frictional resistance. It has the characteristic that noise and vibration are suppressed. In addition, as a sintered oil-impregnated bearing with further enhanced vibration and noise suppression effects,
A gap (hereinafter, referred to as a middle relief portion) having an inner diameter slightly larger than the outer diameter of the rotating shaft and not in contact with the rotating shaft is formed on the inner diameter surface at the central portion in the axial direction. As a two-point support structure limited to a surface, there is a structure in which the effect of reducing frictional resistance and the support force of the rotating shaft are further stabilized.

[0003] Sintered oil-impregnated bearings are usually manufactured mainly by the steps of sintering a cylindrical green compact obtained by compression-molding a raw metal powder, sizing the sintered body and finishing it into a final shape. However, as a bearing, there is a type in which a sintered body is incorporated in a housing in addition to a sintered body alone. By the way, in the case where the above-mentioned middle relief portion is formed, if the middle relief portion is formed by machining the sintered body, the pores exposed on the inner diameter surface are crushed, which hinders the circulation operation of the lubricating oil. Become. For this reason, it is preferable to form the middle relief portion at the same time in the sizing step of the sintered body, or to form the middle relief portion by deforming the sintered body again after sizing. In any case, the two inner shafts are separated from each other by causing plastic deformation in the sintered body such that the inner diameter surfaces at both ends in the axial direction project radially inward or the central portion in the axial direction swells radially outward. The supporting surface and the clearance between them are formed on the inner diameter surface at the same time.

[0004]

In the bearing having the above-mentioned two-point support structure, in order to enhance the bearing performance such as the reduction of the frictional resistance and the improvement of the support force of the rotary shaft, the inner diameter of the two separated shaft supporting surfaces and It is required that the coaxiality match with high accuracy and that the supply amount of the lubricating oil to the bearing surface be sufficient. However, although various methods of plastically deforming a sintered body have been conventionally proposed, a certain manufacturing method that is relatively simple and does not sufficiently satisfy requirements for improving bearing performance has been found at present. there were. Also, in a bearing of a type in which a sintered body is incorporated in a housing, even if the bearing is formed into a housing after forming a bearing surface and an intermediate relief portion, the sintered body is deformed due to deformation. In many cases, the inner diameter of the surface is different or the coaxiality is impaired, and it is extremely difficult to size the sintered body after the assembly to form the bearing surface and the middle relief.

Therefore, the present invention provides a bearing having a two-point support structure in which a sintered body is incorporated in a housing, by a relatively simple method, efficiently and with excellent bearing performance (the inner diameter of two bearing surfaces, It is an object of the present invention to provide a method capable of manufacturing a rotating shaft having a coaxiality having the same bearing capacity, lubricating property, and wear resistance.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method for manufacturing a bearing in which a cylindrical bearing main body is incorporated in a cylindrical housing. A press-fitting step of coaxially press-fitting the material into a housing arranged in a molding hole while maintaining a state in which a uniform core rod is inserted into the material formed in the bearing body. While the outer diameter surface is pressed against the inner diameter surface of the housing, the inner diameter surfaces of both ends in the axial direction of the material are pressed against the core rod to form a bearing surface for supporting the rotating shaft, and the rotation between these bearing surfaces is performed. It is characterized in that a middle escape portion that does not contact the shaft is formed.
As the material according to the present invention, a sintered body or a porous body obtained by sizing the sintered body as described above is used, and after production, the sintered body is impregnated with a lubricating oil and is suitably used as a sintered oil-impregnated bearing.

In the arrangement step, for example, the housing is pressed into the molding hole. In this case, the outer diameter of the housing is larger than the inner diameter of the forming hole, and the housing is tightly fitted in the forming hole. In order to dispose the housing in the molding hole, an intermediate fitting in which the housing is simply inserted into the molding hole and fitted thereto, or a loose fit in which a gap is formed between the outer diameter surface of the housing and the inner diameter surface of the molding hole, may be used. Form.

[0008] In the press-fitting step, the core rod penetrating the housing is inserted into the material, and the material is pushed into the housing while being held in that state. The outer diameter surface of the material is pressed into the housing inner diameter surface by being press-fitted into the housing. The outer diameter shape of the material and the inner diameter shape of the housing are such that, as the material is pressed into the housing, at least both ends in the axial direction of the material are reduced in diameter by being pressed against the inner diameter surface of the housing, and the inner diameters at both ends in the axial direction are reduced. The surface is in pressure contact with the core rod. Further, the inner diameter surface of the material is shaped and dimensioned so that only the axial ends are pressed against the core rod. Preferably, the material and the housing have the same axial length.

As described above, the inner diameter surface of the material pressed against the core rod serves as two spaced-apart bearing surfaces for supporting the rotating shaft. On the other hand, a gap is formed between the shaft supporting surface and the core rod on the inner diameter surface, and serves as a middle escape portion that does not contact the rotating shaft. As a result of the plastic deformation of the material, the material is formed into a bearing body, and the bearing body is pressed against the housing to form a bearing in which the two are integrated.

In the present invention, a form in which the material is reduced in diameter over its entire length is of course included. In this case, in order to form a middle clearance portion on the inner diameter surface of the material, the inner diameter of both ends in the axial direction of the material is made smaller in advance than the center portion so as to be thicker, and only the inner diameter surface of the inner diameter small diameter portion is the core rod. It is configured to be pressed against. When locally reducing the diameter of both ends in the axial direction of the material as described above, the inner diameter of the material may be uniform,
It is also possible to use a material having a shape having a small inner diameter portion at both ends in the axial direction. The small-diameter inner diameter portion of this material may have such a size that the inner diameter surface is in contact with the core rod as long as the middle relief portion is formed reliably.

According to the present invention, by adopting a combination of a material and a housing in which the above-described modification is appropriately made, the bearing main body is configured to be incorporated in the housing, and the amount of clearance is reduced. A bearing having a two-point support structure having a relatively large middle relief can be efficiently manufactured by a relatively simple method.

Further, since the bearing surface formed on the bearing body is formed by pressing the inner diameter surface of the material strongly against the core rod, the inner diameter and the coaxiality coincide with high accuracy. Further, since the density of the bearing surface can be increased, the wear resistance is improved. On the other hand, it is possible to make the density of the inner diameter surface where the middle relief portion is formed lower than that of the bearing surface, and it is possible to form the diameter of the middle relief portion relatively large, so that the lubricating oil content and the oil retention amount are reduced. It can be increased, and the lubricity is improved. As a result, a bearing having a high level of bearing performance can be manufactured.

Further, the present invention is characterized in that a convex portion or a concave portion for forming a dynamic pressure groove is formed on the outer diameter surface of the core rod which is pressed against the inner diameter surfaces of both ends in the axial direction of the material. According to this, in the case of the former convex portion, a dynamic pressure groove corresponding to the shape of the convex portion is formed on the bearing surface. In the case of the latter concave portion, a bearing surface engraved according to the shape of the concave portion and a dynamic pressure groove between the bearing surfaces are simultaneously formed. When the dynamic pressure grooves are formed on the bearing surface, the dynamic pressure effect generated in the dynamic pressure grooves (the lubricating oil flowing into the dynamic pressure grooves) Increased rigidity with higher pressure)
Accordingly, the supporting force of the rotating shaft is synergistically increased, and the supporting force of the rotating shaft can be further stabilized.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. (1) First Embodiment-FIG. 1 FIGS . 1A to 1C show a bearing forming process according to a first embodiment.
These are shown in the order of (d). In the present embodiment, the housing 21 is arranged in the die 31 of the molding apparatus, and then the material 1A is press-fitted into the housing 21 to manufacture a bearing.

As shown in FIG. 1, the molding apparatus includes a die 31 having a molding hole 30 into which the housing 21 is press-fitted, a core rod 32 having a uniform outer diameter, and upper and lower punches 33 and 34. The forming hole 30 of the die 31 has a shape corresponding to the housing 21. As shown in FIG. 1A, the forming hole 30 is provided on the inlet side (upper side) of the cylindrical main portion 30a via a horizontal step portion 30d. An opening 30c having a larger diameter than the main portion 30a is formed. As shown in FIG. 1B, the upper punch 33 is slidably inserted into the opening 30c of the molding hole 30, and the lower punch 34 slides on the main portion 30a of the molding hole 30. It is designed to be movably inserted. The core rod 32 includes upper and lower punches 33 and 34.
It is slidably penetrated.

As shown in FIG. 1 (a), the housing 21 has a uniform inner diameter, and has a cylindrical shape in which a flange 23 is formed at one end of a cylindrical portion 22 which forms a main body. Cylindrical part 2
The outer diameter of 2 is larger than the inner diameter of the main part 30a of the forming hole 30, and the outer diameter of the flange 23 is set to be larger than the inner diameter of the opening 30c. Further, with respect to the axial length (height), the cylindrical portion 22 is set shorter than the main portion 30a of the forming hole 30, and the flange 23 is set shorter than the opening 30c. The housing 21 is made of a material that can be press-fit into the forming hole 30 while being plastically deformed. For example, bronze, brass,
Sintered materials are used in addition to aluminum alloys and steels. In the case of using a sintered material, if a material having pores larger than the material 1A is used, the oil impregnated in the housing 21 is effectively supplied to the bearing main body side by capillary force, so that the bearing life can be extended. preferable.

The material 1A shown in FIG. 1C is a sintered body or a cylindrical porous body formed by sizing the sintered body. The outer diameter surface of the material 1A is mainly composed of an outer diameter small diameter portion 4a having an outer diameter larger than the inner diameter of the housing 21, and an outer diameter large diameter portion 4b having a diameter larger than the outer diameter small diameter portion 4a at one end. Is formed. The inner diameter surface of the material 1A mainly includes an inner diameter large diameter portion 3b having a diameter larger than the diameter of the core rod 32, and the other end portion (an end opposite to the outer diameter large diameter portion 4b) has an inner diameter small diameter portion 3a. Are formed. Inside diameter small diameter part 3
a small gap is formed between the inner diameter surface of the core rod 32 and the inner diameter surface of the core rod 32.
And the core rod 32. The axial length of the material 1A is set equal to that of the housing 21.

Next, a procedure for manufacturing a bearing by a molding apparatus will be described. [Step 1-Housing Arrangement] As shown in FIG. 1A, the upper end of the lower punch 34 inserted into the main portion 30a of the forming hole 30 of the die 31 is held at the same level as the step portion 30d, while the core rod 32 is held. From the upper surface of the die 31 for a predetermined length. Next, the housing 21 with the flange 23 facing up
Is coaxially fitted into the core rod 32 to form a lower punch 34.
Set on top. Next, the upper punch 33 is lowered as shown in FIG.
1 is pressed into the forming hole 30. The lower punch 34 is lowered together with the housing 21. In the housing 21, the cylindrical portion 22 is press-fitted into the main portion 30 a of the forming hole 30, and the flange 23 is press-fitted into the opening 30 c, and the outer diameter surface is restrained by the die 31.

[Step 2—Press-fitting of Material] After the upper punch 33 is lifted and retracted once, as shown in FIG.
The material 1A is fitted to the core rod 32 with the outer diameter large diameter portion 4b facing upward, and set on the housing 21. Next, as shown in FIG. 1D, the upper punch 33 is lowered again, and the material 1A is pushed into the housing 21 by the upper punch 33 and press-fitted. At this time, the core rod 32 is moved down following the material 1A.

When the material 1A is pressed into the housing 21, its outer diameter surface is plastically deformed in accordance with the inner diameter surface of the housing 21, and its diameter is reduced over its entire length. The diameter surface becomes straight, and the outer diameter surface is pressed against the inner diameter surface of the housing 21. The small-diameter portion 3a at the lower end of the material 1A protrudes toward the inner diameter side, and its inner diameter surface is pressed against the core rod 32 to support the rotary shaft 1.
2 is formed. Further, the flesh of the disappeared outer diameter large diameter portion 4b plastically flows toward the inner diameter side, and the inner diameter surface thereof corresponds to the core rod 32.
Is formed on a shaft support surface 12 that presses against the shaft to support the rotating shaft.
The large inner diameter portion 3b remains between the upper and lower shaft support surfaces 12,
It is formed in the escape portion 13 where the rotating shaft does not contact.

As a result of the plastic deformation of the material 1A, the material 1A is formed into the bearing body 10A, and the bearing 20A in which the bearing body 10A and the housing 21 are integrated is formed. The bearing 20A raises and retracts the upper punch 33 and, together with the core rod 32, lower punch 3
4 can be removed from the die 31 by raising it, and then the core rod 32 can be taken out by lowering.

According to the first embodiment, the housing 2
1 is press-fitted into the die 31 and then the raw material 1A is press-fitted into the housing 21 by a simple method such that the bearing body 10A made of a sintered body is incorporated in the housing 21. The bearing 20A can be manufactured efficiently.

Since the bearing surface 12 of the bearing 20A is formed by pressing the inner diameter surface of the material 1A strongly against the core rod 32, the inner diameter and the coaxiality match with high precision, and the density is increased. Excellent in abrasion resistance and rotating shaft support force. On the other hand, since the middle relief portion 13 does not press against the core rod 32, the density is lower than that of the bearing surface 12, and the middle relief amount can be made relatively large. The amount can be increased and lubricity is improved. As a result, the bearing 20A exhibits excellent bearing performance. In addition, since the degree of compression of both bearing surfaces 12 can be made substantially equal, the porosity of those bearing surfaces 12 is equalized, and therefore, the bearing surfaces 12
And the hydraulic pressure generated at the same time is equalized, and the rotating shaft can be supported in a well-balanced manner.

In the above embodiment, the housing 21
The outer diameter of the hole is a size that is pressed into the forming hole 30 to be tightly fitted. However, the outer diameter is a size that is fitted into the forming hole 30 in the middle, or a slight gap is formed between the outer diameter of the forming hole 30 and the inner diameter surface. The dimensions may be such that the loose fit is formed. If the outer diameter of the housing 21 is such that there is a gap between the outer diameter surface of the housing 21 and the fitting hole 30, the housing 21 is press-fitted when the material 1A is pressed.
Although it is not preferable because there is a possibility that the diameter of the housing 21 may be increased, it is not limited as long as the housing 21 has a high rigidity and expands in an elastic deformation region, that is, does not plastically deform.

(2) Second Embodiment FIG. 2 Next, a second embodiment of the present invention will be described. The forming apparatus according to the second embodiment is obtained by changing the forming hole 30 and the lower punch 34 of the die 31 used in the first embodiment. The molding hole 30 in this case is, as shown in FIG.
A small-diameter portion 30b having a smaller diameter than the main portion 30a is formed in a deeper portion (lower portion) of the lower portion 3a.
4 is inserted. In the second embodiment, a housing 21 similar to that of the first embodiment, and FIG.
A bearing is manufactured from the material indicated by reference numeral 1B in (c).

In this case, the outer diameter of the cylindrical portion 22 of the housing 21 is larger than the inner diameter of the small-diameter portion 30b and slightly smaller than the inner diameter of the main portion 30a of the forming hole 30. Reference numeral 22 is set to a size that fits in the state of intermediate fitting. The outer diameter of the flange 23 is set to be larger than the inner diameter of the opening 30c as in the first embodiment.

The material 1B has a uniform outer diameter, and the outer diameter is set larger than the inner diameter of the housing 21. The inner diameter surface mainly includes an inner diameter large diameter portion 3b having a diameter larger than the diameter of the core rod 32, and an inner diameter small diameter portion 3a is formed at one end in the axial direction. A minute gap is formed between the inner diameter surface of the inner diameter small diameter portion 3a and the core rod 32, and a gap larger than this gap is formed between the inner diameter large diameter portion 3b and the core rod 3.
2 is formed.

Next, a procedure for manufacturing a bearing by a molding apparatus will be described. [Step 1-Housing Arrangement] As shown in FIG. 2A, the housing 21 with the flange 23 facing upward is set in a molding apparatus, and then, as shown in FIG. Into the forming hole 30. In the housing 21, the lower end of the cylindrical portion 22 is press-fitted into the small diameter portion 30b of the forming hole 30, the narrowed portion 25 is formed, and the flange 23 is press-fitted into the opening 30c. Housing 21
Is in a state where the outer diameter surface is restricted by the die 31.

[Step 2—Press-fitting of Material] After the upper punch 33 is lifted and retracted once, as shown in FIG.
The material 1B is fitted to the core rod 32 with the small-diameter portion 3a facing upward, and set on the housing 21. Next, as shown in FIG. 2D, the material 1B is pushed into the housing 21 by the upper punch 33 and press-fitted. At this time, the core rod 32 is moved down following the material 1B.

When the material 1B is press-fitted into the housing 21, its outer diameter surface is plastically deformed to follow the inner diameter surface of the housing 21, and its diameter is reduced over its entire length. Thus, the squeezed portion 11 is formed, and the outer diameter surface is pressed against the inner diameter surface of the housing 21. The inner diameter surface of the throttle unit 11 is pressed against the core rod 32,
It is formed on a shaft support surface 12 that supports the rotation shaft. The large-diameter large-diameter portion 3b at the upper end of the material 1B protrudes toward the inner diameter side, and the inner diameter surface is formed on the shaft support surface 12 that presses against the core rod 32 and supports the rotating shaft. The large-diameter large-diameter portion 3b remains between the upper and lower shaft supporting surfaces 12, and the middle relief portion 1 where the rotating shaft does not contact.
3 is formed.

By plastically deforming the material 1B, the material 1B is formed into the bearing body 10B, and the bearing 20B in which the bearing body 10B and the housing 21 are integrated is formed. The bearing 20B raises and retracts the upper punch 33, and moves the lower punch 3 together with the core rod 32.
4 can be removed from the die 31 by raising it, and then the core rod 32 can be taken out by lowering.

(3) Third Embodiment—FIGS. 3 and 4 In the third embodiment, as shown in FIG.
This is an example in which a core rod 32A for forming a dynamic pressure groove in place of 2 is applied to the first embodiment to form a raw material 1A and a bearing in which a dynamic pressure groove is formed on a shaft support surface 12. As shown in FIG. 4 (a), the core rod 32A has a plurality of V-shaped protrusions 32a herring at equal intervals in the circumferential direction on an outer diameter surface of the material 1A which receives pressure contact between inner diameter surfaces at both ends. It is formed in a bone shape. The protrusion 32a is formed by the core rod 3
It can be formed by means such as cutting or plating of 2A, and its height is about several μm.

In order to form the bearing, the housing 21 is press-fitted into the forming hole 30 in the same manner as in the first embodiment, and then, as shown in FIG. The portions of the core rod 32A where the protrusions 32a are formed correspond to the inner diameter surfaces of both ends of the material 1A. From this state, as shown in FIG. 3B, the raw material 1A is pressed into the housing 21 by the upper punch 33 while the core rod 32A is lowered, and the bearing 20C in which the bearing body 10C is incorporated in the housing 21 is obtained.

The bearing surface 12 of the bearing body 10C has a structure shown in FIG.
As shown in (b) (the housing 21 is omitted in the figure), a herringbone-shaped dynamic pressure groove 14 is formed by the projection 32a of the core rod 32A. Since the restraint on the outer diameter surface by the die 31 is released to the removed bearing 20C, spring back occurs in which the entire diameter slightly increases,
The core rod 32 without abrasion of the projections between the dynamic pressure grooves 14.
The bearing 20C can be removed from A.

Bearing 20 manufactured according to the third embodiment
According to C, in addition to the two-point support structure that supports the rotating shaft on the shaft supporting surface 12, due to the dynamic pressure effect generated in the dynamic pressure groove 14 (improved rigidity due to the high pressure of the lubricating oil flowing into the dynamic pressure groove). The supporting force of the rotating shaft increases synergistically, and the supporting force of the rotating shaft becomes more stable. From the viewpoint that the effect that the lubricating oil concentrates on a part of the dynamic pressure groove 14 and the dynamic pressure rises is sufficiently expected, the bearing 20
C is preferably set so that the rotation direction of the rotating shaft is oriented in the direction of the V-shaped tip of the dynamic pressure groove 14 (the direction of arrow R in FIG. 4B).

The form in which the dynamic pressure grooves are formed on the bearing surface using the core rods 32A for forming the dynamic pressure grooves as in the third embodiment can be applied to the second embodiment.

The shape of the dynamic pressure groove shown in the third embodiment is arbitrary, and the number thereof is also selected as appropriate. However, from the viewpoint of more stably supporting the rotating shaft, a plurality of grooves are formed on the bearing surface. It is preferable that they are arranged at equal intervals along the circumferential direction. In the third embodiment, the effect of increasing the dynamic pressure is obtained as a herringbone shape, that is, depending on the shape.
The effect can also be obtained depending on the cross-sectional shape of the depth.

In order to achieve this, the general shape is a groove extending along the axial direction. When the rotating shaft rotates in only one direction, the end of the rotating shaft in the direction opposite to the rotating direction is the deepest portion. From the section to the direction of rotation of the rotating shaft. When the rotating shaft rotates in both the forward and reverse directions, the middle part in the circumferential direction is set as the deepest part, and the inclination is made so as to gradually become shallower from the deepest part toward both ends in the circumferential direction. The thus formed dynamic pressure groove has a wedge-shaped gap in which the cross-section (cross-section when cut into a circle) becomes shallower in the direction of rotation of the rotary shaft, and the lubricating oil concentrates on the shallow tip of the groove. A wedge effect can be obtained.

The dynamic pressure groove 14 shown in the third embodiment
Is formed by the convex portion 32a formed on the core rod 32A, but a dynamic pressure groove can be formed by a concave portion instead of such a convex portion. That is, the pattern of the engraving is opposite to that of the third embodiment, and when the inner diameter surface of the inner diameter small diameter portion of the material 1A is pressed against the core rod, it is introduced into the concave portion formed in the core rod, and the convex portion protrudes. The inner diameter surface of the convex portion functions as a bearing surface, and the groove between the convex portions functions as a dynamic pressure groove. In this case, by further projecting the convex portion, a bearing having a large amount of middle clearance by its height can be obtained. The concave portion formed in the core rod can be formed by means such as electric discharge machining or electrolytic corrosion.

[0040]

As described above, according to the present invention,
The bearing body is configured to be incorporated in the housing,
A two-point support structure bearing with a relatively large middle relief
It can be efficiently manufactured by a relatively simple method. In the bearing manufactured by the present invention, the inner diameter and the coaxiality of the bearing surfaces at both ends in the axial direction are matched with high accuracy, and the density is increased to improve wear resistance.
On the other hand, in the central portion in the axial direction where the middle relief portion is formed,
Since the density is low, the content of lubricating oil and the amount of retained oil are sufficiently ensured. As a result, excellent bearing performance is exhibited.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a manufacturing process of a bearing according to a first embodiment of the present invention in the order of (a) to (d).

FIG. 2 is a longitudinal sectional view showing a manufacturing process of a bearing according to a second embodiment of the present invention in the order of (a) to (d).

FIG. 3 is a longitudinal sectional view showing a part of a manufacturing process of a bearing according to a third embodiment of the present invention in the order of (a) and (b).

FIG. 4A is a partial perspective view of a core rod used in a third embodiment of the present invention, and FIG. 4B is a vertical perspective view showing a part of a bearing manufactured in the third embodiment.

[Explanation of symbols]

 1A, 1B ... Material 10A, 10B, 10C ... Bearing body 12 ... Bearing support surface 13 ... Medium relief portion 14 ... Dynamic pressure groove 20A, 20B, 20C ... Bearing 21 ... Housing 30 ... Forming hole 32, 32A ... Core rod 32a ... Driving Protrusions for forming pressure grooves

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J011 AA04 BA02 CA01 CA02 DA02 JA02 LA01 SB19 4K018 CA13 CA15 FA02 JA34 KA03 KA22

Claims (2)

[Claims] 1. A method of manufacturing a bearing, comprising a cylindrical bearing main body incorporated in a cylindrical housing, comprising: an arranging step of arranging the housing in a molding hole; Press-fitting the material coaxially into a housing arranged in the molding hole while maintaining the state of being inserted into the material to be molded into the material. While being pressed against the inner diameter surface, the inner diameter surfaces of both ends in the axial direction of the material are pressed against the core rod to form a bearing surface for supporting the rotating shaft, and a clearance between these bearing surfaces that does not contact the rotating shaft. A method for manufacturing a bearing, comprising forming a portion. 2. A convex portion or a concave portion for forming a dynamic pressure groove is formed on an outer diameter surface of the core rod to which inner diameter surfaces of both ends in the axial direction of the material are pressed. 3. The method for producing a bearing according to item 1.