JP2001050275A - 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 press-fitting and positioning a raw material or sintered body 1A to form a bearing body 10A in a housing 21 coaxially to unite them both temporarily, and a press-fitting step of press-fitting the housing 21 as it carries the raw material 1A in a forming hole 30 of a die 31 after a core rod 32 of a uniform outside diameter has been inserted in 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 constricts the housing 21 diametrally through the overall length. The diametral constriction of the housing 21 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, wherein a cylindrical material molded into the bearing main body is provided in the housing. An arrangement step of substantially coaxial arrangement, and a press-fitting step of pressing the housing together with the material into a molding hole by pressing the housing together with the material from a state in which a core rod having a uniform outer diameter is inserted into the material arranged in the housing, While the outer diameter surface of the material is pressed against the inner diameter surface of the housing, at least both ends in the axial direction of the housing are reduced in diameter, and the inner diameter surfaces of both ends in the axial direction of the material are pressed against the core rod by the reducing action of the housing. It is characterized in that it is formed on a bearing surface that supports the rotating shaft, and that a middle relief portion that does not contact the rotating shaft is formed between these bearing surfaces. 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.

[0007] In the arrangement step, for example, a material is press-fitted into a housing to temporarily integrate them. In this case, the outer diameter of the material is larger than the inner diameter of the housing, and the material is tightly fitted in the housing. Preferably, the material and the housing have the same axial length. In order to place the material in the housing, there are forms such as an intermediate fitting where the material is simply inserted into the housing and fitted, or a loose fit where there is a gap between the outer diameter surface of the material and the inner diameter surface of the housing. Can be

In the press-fitting step, the housing is pushed into the forming hole along the axial direction with the core rod inserted into the material in the housing, and the material is press-fitted. Simultaneously with this press-fitting, both may be compressed in the axial direction. The outer diameter of the housing and the inner diameter of the forming hole are such that at least both ends in the axial direction of the housing are reduced in diameter by being pressed against the inner surface of the forming hole as the housing is pressed into the forming hole. In addition, when the inner diameter is uniform, the inner diameter of the material is set to such a size that a gap is formed between the inner diameter surface and the core rod. In the housing press-fitted into the molding hole, at least both ends in the axial direction are pressed against the inner diameter surface of the molding hole to reduce the diameter. Then, the reduced diameter portion presses the material, and the material is also reduced in diameter, and the inner diameter surfaces of both ends in the axial direction of the material are pressed against the core rod. In this way, the inner diameter surfaces that are in pressure contact with the core rod are two spaced-apart bearing surfaces that support the rotating shaft. On the other hand, the inner diameter surface between these shaft support surfaces does not decrease in diameter, and a gap remains between the core rod and the core support rod. As a result of the plastic deformation of the housing and the raw material, the raw material is formed on the bearing main body, and is pressed against the inner diameter surface of the housing to form a bearing in which both are integrated.

The present invention naturally includes a mode in which the diameter of the housing is reduced over the entire length. In this case, the diameter of the material is reduced along the entire length of the material together with the housing, so that the inside diameter of both ends in the axial direction of the material is made smaller in advance than the center to increase the wall thickness so that a middle clearance portion is formed. Is configured so that only the inner diameter surface thereof is pressed against the core rod. When locally reducing the diameter of both ends in the axial direction of the housing as described above, the inner diameter of the material may be uniform, but a material having a small inner diameter portion at both axial ends may be used. it can. This small-diameter inner diameter portion may have such a size that its inner diameter surface is in contact with the core rod as long as the middle relief portion is formed reliably. The small-diameter portion may be formed by deforming the material when the material is pressed into the housing in the arranging step.

Although the diameter of the housing and the arrangement of the material in the housing (tight fit, intermediate fit, or loose fit) have a correlation with each other, they are reduced during the press-fitting step of the housing. When the diameter is adjusted, the material is press-fitted to the housing so that the two are integrated, and the bearing surface and the intermediate relief portion can be reliably formed on the inner diameter surface of the material.

According to the present invention, the bearing body is incorporated in the housing by adopting a combination of a material and a housing and a molding die in which the above-mentioned deformation mode is appropriately made. A bearing having a two-point support structure having a relatively large amount of 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, FIG.
As shown in (1), the raw material 1A is placed in the housing 21 in advance, and the housing 21 is pressed into the forming hole of the forming device together with the raw material 1A to manufacture a bearing.

As shown in FIGS. 1B to 1D, 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. It is composed of The molding hole 30 of the die 31 has a shape corresponding to the housing 21 and is formed as shown in FIG.
As shown in (b), an opening 30c having an inner diameter larger than that of the main portion 30a is formed on the entrance side (upper side) of the cylindrical main portion 30a via a horizontal step portion 30d. The upper punch 33 is slidably inserted into the opening 30 c of the forming hole 30, and the lower punch 34 is
Is slidably inserted into the main portion 30a of the main body. The core rod 32 is slidably penetrated by upper and lower punches 33 and 34.

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 raw material 1A is a sintered body or a cylindrical porous body formed by sizing the sintered body. The outer diameter of the material 1A is uniform, and is set to be larger than the inner diameter of the housing 21 to such an extent that the material 1A fits in the housing 21 in a tight fit state. Further, the inner diameter is non-uniform, and the inner diameter small-diameter portions 3a are formed at both ends in the axial direction, and the central portion is the inner diameter large-diameter portion 3b having a diameter larger than the inner diameter small-diameter portion 3a. As shown in FIG. 1B, the small-diameter inner diameter portion 3a is set to have such a size that a minute gap is formed between the inner-diameter surface and the core rod 32 even when fitted in the housing 21. . 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-Arrangement of Material in Housing] As shown in FIG. 1A, the material 1A is press-fitted into the housing 21 by an appropriate device other than the above-described molding device, and fitted into a tight fit. The two are temporarily integrated.

[Step 2—Press Fitting of Housing] FIG. 1 (b)
As shown in (2), while holding the upper end of the lower punch 34 at the same level as the step portion 30d of the forming hole 30 of the die 31, the core rod 32 is protruded from the upper surface of the die 31 by a predetermined length to be in a standby state. The material 1 </ b> A is coaxially fitted to the core rod 32 with the flange 23 of the housing 21 disposed above, and the housing 21 and the material 1 </ b> A are set on the lower punch 34. Next, as shown in FIG. 1C, the upper punch 33 and the core rod 32 are both lowered, and the housing 21 is pushed into the forming hole 30 together with the raw material 1A by the upper punch 33 and press-fitted. The lower punch 34 is lowered together with the housing 21.

When the housing 21 is pressed into the forming hole 30, the cylindrical portion 22 is pressed against the inner diameter surface of the main portion 30a of the forming hole 30 to reduce the diameter, and the flange 23 is pressed against the inner diameter surface of the opening 30c. Reduce diameter. That is, the diameter of the housing 21 is reduced over the entire length, and accordingly, the material 1A is reduced in diameter over the entire length, and is pressed against the inner diameter surface of the housing 21. When the diameter of the material 1A is reduced, the small-diameter inner diameter portion 3a is pressed against the core rod 32, and the inner diameter surface forms the bearing surface 12 that supports the rotating shaft. In addition, the large-diameter portion 3b between the shaft supporting surfaces 12 remains, and the middle escape portion 13 with which the rotating shaft does not contact.
Formed. Thus, the housing 21 and the material 1
A is plastically deformed, so that the material 1A is
A, and a bearing 20A in which the bearing main body 10A and the housing 21 are integrated is formed.

[Step 3—Removal of Bearing] As shown in FIG. 1D, the upper punch 33 is raised and retracted, the lower punch 34 is raised together with the core rod 32, and the bearing 20A is pulled out from the die 31. Demold. Thereafter, the core rod 32 is lowered to obtain the bearing 20A.

According to the first embodiment, the raw material 1A is press-fitted into the housing 21, and the housing 21 is press-fitted into the forming hole 30 of the die 31 together with the raw material 1A. Bearing 20A having a two-point support structure in which a bearing body 10A
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. Further, since the degree of compression of both the bearing surfaces 12 is substantially equal, the porosity of the bearing surfaces 12 is equalized. Therefore, the hydraulic pressure generated on the bearing surfaces 12 is also equalized and the rotating shaft is well balanced. Can be supported.

Next, second and third embodiments of manufacturing a bearing from a material having a shape different from that of the material 1A of the first embodiment using the above-described molding apparatus will be described.

(2) Second Embodiment—FIG . 2 The material of the second embodiment indicated by reference numeral 1B in FIG . 2A has a uniform outer diameter, an outer diameter large diameter portion 4b at one axial end, and , A cylindrical shape having a small-diameter portion 3a formed at the other end. The outer diameter of the outer diameter large diameter portion 4b is larger than the inner diameter of the housing 21, and the outer diameter of the outer diameter small diameter portion 4a, which is the outer diameter portion other than the outer diameter large diameter portion 4b, is in a state of being fitted in the housing 21 in the middle. The dimensions are set to fit. Note that the outer diameter of the outer diameter small diameter portion 4a may be set to a size that fits in the housing 21 in a tightly fitted state, similarly to the outer diameter of the material 1A of the first embodiment. The inner diameter of the small-diameter inner diameter portion 3a is set to a size at which a minute gap is formed between the inner diameter surface of the small-diameter inner diameter portion 3a and the core rod 32. It is set larger than the inner diameter small diameter portion 3a.

Next, a procedure for manufacturing a bearing by a molding apparatus will be described. [Step 1-Arrangement of Material in Housing] As shown in FIG.
1 is fitted from the flange 23 side to be in an intermediate fitting state. Next, the core rod 32 of the molding apparatus in a standby state is
The material 1A is fitted with the flange 23 of the housing 21 and the large-diameter outer diameter portion 4b of the material 1B disposed above, and the housing 21 is set on the lower punch 34. Then, FIG.
As shown in (b), the upper punch 33 is lowered, and the material 1B is pushed into the housing 21 by the upper punch 33. At this time, the core rod 32 is also lowered while maintaining a state in which the core rod 32 does not come off from the material 1B. When the material 1B is pushed into the housing 21, the large-diameter outer diameter portion 4b disappears due to press-fitting, and the corresponding portion of the material 1B plastically flows to the internal diameter side, and the small-diameter internal diameter portion 3a is newly formed at the upper end. You. Large diameter part 3b
Remains at the center in the axial direction. Thereby, the material 1B and the housing 21 are temporarily integrated.

[Step 2—Press Fitting of Housing] FIG. 2 (c)
The upper punch 33 and the core rod 32 are both lowered as shown in FIG.
Into the forming hole 30 and press fit. Housing 21
And the material 1B are reduced in diameter as in the first embodiment.
B is a bearing body 1 having a bearing surface 12 and a middle relief 13
The bearing 20B is molded into a bearing 0B and is pressed against the inner diameter surface of the housing 21 to form an integrated bearing 20B. Bearing 2
0B is the same operation as in the first embodiment (see FIG. 1D)
Demolded by

(3) Third Embodiment—FIG. 3 In the third embodiment, as shown in FIG. 3A, a housing 21 A is used instead of the housing 21. The housing 21A has a small inner diameter portion 24a formed on the inner diameter surface at the end on the flange 23 side, and the other inner diameter portion is a large inner diameter portion 24b. Other configurations and dimensions are the same as those of the housing 21.

On the other hand, the material of the third embodiment indicated by reference numeral 1C in FIG. 3A has a uniform outer diameter, a small inner diameter portion 3a formed at one end in the axial direction, and another inner diameter portion having a large inner diameter portion. 3b. The outer diameter of the material 1C is set to be larger than the inner diameter of the small-diameter inner diameter portion 24a of the housing, and a small gap is formed between the outer-diameter surface and the large-diameter large-diameter portion 24b so as to be in a loose fit state. Have been. As for the inner diameter, the inner diameter of the inner diameter small diameter portion 3 a is set to a size at which a minute gap is formed between the inner diameter surface and the core rod 32. The outer diameter of the material 1C is
1 may be set to a size that fits in the state of intermediate fitting.

Next, a procedure for manufacturing a bearing by a molding apparatus will be described. [Step 1-Arrangement of Material in Housing] As shown in FIG. 3A, the core rod 32 of the molding apparatus in a standby state is
The material 1C having the smaller inner diameter portion 3a side is fitted thereon and placed on the lower punch 34, and the housing 21A having the flange 23 disposed thereon is fitted into the material 1C. Then, FIG.
As shown in FIG.
A is lowered, and the upper end of the material 1C is pressed into the small inner diameter portion 24a of the housing 21A. Then, the upper end portion of the material 1 </ b> C is reduced in diameter to form the narrowed portion 11, and the inner diameter surface of the narrowed portion 11 is pressed against the core rod 32. The inner diameter large diameter portion 3b is
It remains at the axial center. As a result, the material 1C and the housing 21A are temporarily integrated.

[Step 2—Press Fitting of Housing] FIG. 3 (c)
The upper punch 33 and the core rod 32 are both lowered as shown in FIG.
The entire C is pressed into the forming hole 30 and press-fitted. Housing 2
1A is reduced in diameter over its entire length by being pressed by the inner diameter surface of the molding hole 30, and the material 1C is also reduced in diameter over its entire length by the diameter reducing action of the housing 21A. Thereby, material 1C
Bearing body 10 having a bearing surface 12 and a middle relief 13
C, and is pressed against the inner diameter surface of the housing 21A to form a bearing 20C in which both are integrated. Bearing 2
0C is the same operation as in the first embodiment (see FIG. 1D).
Demolded by

Next, fourth and fifth embodiments of manufacturing a bearing by using a molding apparatus different from the above-mentioned molding apparatus will be described.

(4) Fourth Embodiment—FIG. 4 The molding apparatus of the fourth embodiment is obtained by changing the molding hole 30 of the die 31 used in the first to third embodiments. As shown in FIG. 4 (a), the forming hole 30 is provided at a deep portion (lower portion) of the main portion 30a at a small diameter portion 30 having a smaller diameter than the main portion 30a.
The lower punch 34 is inserted into the small diameter portion 30b. In the fourth embodiment, a housing 21 similar to those of the first and second embodiments is provided.
A bearing is manufactured from the material indicated by reference numeral 1D in (a).

In this case, the outer diameter of the cylindrical portion 22 of the housing 21 is set to a size that fits into the main portion 30a of the forming hole 30 in an intermediately fitted state. The outer diameter of the cylindrical portion 22 is smaller than the inner diameter of the main portion 30a, and is set to a size in which a small gap is formed between the outer diameter surface and the inner diameter surface of the main portion 30a so as to be in a loose fitting state. May be. Meanwhile, material 1D
Is the same as the material 1C of the third embodiment, and its outer diameter is set to be larger than the inner diameter of the housing 21 to such an extent that it fits in the housing 21 in a tightly fitted state.

Next, a procedure for manufacturing a bearing by a molding apparatus will be described. [Step 1-Arrangement of Material in Housing] As shown in FIG. 4A, the material 1D is placed in the housing 21 by an appropriate device other than the above-described molding device in a state in which the small-diameter portion 3a corresponds to the flange 23. And press fit into a tight fit to temporarily integrate them.

[Step 2—Press Fitting of Housing] FIG. 4 (a)
As shown in FIG.
The material 1D is fitted with the flange 23 of the housing 21 and the small-diameter portion 3a of the material 1D arranged on the upper side, and set on the lower punch 34. Next, as shown in FIG. 4B, the upper punch 33 and the core rod 32 are both lowered, and the upper punch 33 pushes the housing 21 into the forming hole 30 together with the material 1D.

In the housing 21 press-fitted into the molding hole 30, the diameter of the flange 23 is reduced, and the lower end is formed at the molding hole 30.
The diameter of the narrowed portion 25 is reduced by being press-fitted into the small diameter portion 30b. By reducing the diameter of the flange 23, the material 1
The inner diameter surface of the inner diameter small diameter portion 3a at the upper end of D is the core rod 32.
And is formed on the bearing surface 12. Also, the squeezing section 25
Is formed at the lower end of the material 1D, and the inner diameter surface is formed on the shaft support surface 12. Housing 2 corresponding to main portion 30a of forming hole 30
The first cylindrical portion 22 does not reduce in diameter only by sliding on the main portion 30a, and the large-diameter portion 3b remains in the material 1D, and the middle escape portion 1
3 is formed. In this way, the material 1D is plastically deformed, and the bearing body 10 having the shaft support surface 12 and the middle relief 13 is formed.
D, and is pressed against the inner diameter surface of the housing 21 to form a bearing 20D in which both are integrated. Bearing 2
0D is the same operation as in the first embodiment (see FIG. 1D)
Demolded by

(5) Fifth Embodiment—FIG. 5 In the fifth embodiment, the molding apparatus according to the fourth embodiment is used,
A bearing is manufactured from the same housing 21A as in the embodiment and a material indicated by reference numeral 1E in FIG. In this case, the outer diameter of the cylindrical portion 22 of the housing 21A is set to a size that fits into the main portion 30a of the forming hole 30 in an intermediately fitted state. The outer diameter of the cylindrical portion 22 is smaller than the inner diameter of the main portion 30a, and is set to a size in which a small clearance is formed between the outer diameter surface and the inner diameter surface of the main portion 30a. It may be. On the other hand, the raw material 1E is a simple cylindrical shape having both uniform outer and inner diameters. The outer diameter of material 1E is
The dimensions are set so as to fit into the large-diameter inner diameter portion 24b of the housing 21A in an intermediate fitting state. The inner diameter is set to a size at which a minute gap is formed between the inner diameter surface and the core rod 32.

Next, a procedure for manufacturing a bearing by a molding apparatus will be described. [Step 1-Arrangement of Material in Housing] As shown in FIG. 5A, the upper end of the lower punch 34 is
0a. And the core rod 32
The material 1E is fitted on the lower punch 34, and the housing 21A having the flange 23 disposed thereon is fitted into the material 1E. Next, as shown in FIG. 5B, the housing 21A is lowered by the upper punch 33 to insert the lower portion of the cylindrical portion 22 into the main portion 30a of the forming hole 30, and the material 1E is formed.
Is pressed into the small inner diameter portion 24a of the housing 21A. Then, the upper end of the material 1E is reduced in diameter, and
1 is formed, and the inner diameter surface of the narrowed portion 11 is pressed against the core rod 32. Thereby, the material 1E and the housing 21A are temporarily integrated.

[Step 2—Press Fitting of Housing] FIG. 5 (c)
The upper punch 33 and the core rod 32 are both lowered as shown in FIG.
E is pressed into the forming hole 30 by press-fitting. Housing 2
1A, similarly to the fourth embodiment, the flange 23 and the lower end are reduced in diameter, and a narrowed portion 25 is newly formed at the lower end. The material 1E is pressed against the inner diameter surface of the housing 21A, and the inner diameter surfaces of the upper and lower throttles 11 are
Is formed on the shaft support surface 12 by pressing against the inner surface, and a clearance between the shaft support surface 12 and the core rod 32 remains to form a middle relief portion 13. In this way, the material 1E is plastically deformed and formed into the bearing body 10E having the shaft support surface 12 and the middle relief portion 13, and the bearing 20E in which the bearing body 10E and the housing 21A are integrated is formed. The bearing 20D is released by the same operation as that of the first embodiment (see FIG. 1D).

(6) Sixth Embodiment—FIGS. 6, 7 In the sixth 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. 7 (a), the core rod 32A has a plurality of V-shaped protrusions 32a herring at equal intervals in the circumferential direction on the outer diameter surface of the material 1A which receives pressure contact between the 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.

As shown in FIG. 6 (a), the housing 21 into which the material 1A is press-fitted is set in a molding apparatus, and the portions of the core rod 32A where the projections 32a are formed correspond to the inner diameter surfaces at both ends of the material 1A. . From this state, the same operation as in the first embodiment (FIGS. 6B to 6C) is performed to obtain a bearing 20F in which the bearing body 10F is incorporated in the housing 21.

As 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 constraint on the outer diameter surface by the die 31 is released in the removed bearing 20F, spring back occurs in which the entire diameter slightly expands.
The core rod 32 without abrasion of the projections between the dynamic pressure grooves 14.
The bearing 20F can be removed from A.

Bearing 20 manufactured according to the sixth embodiment
According to F, in addition to the two-point support structure for supporting 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
F 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. 7B).

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 sixth embodiment can be applied to the second to fifth embodiments. .

The shape of the dynamic pressure groove shown in the sixth embodiment is arbitrary, and the number thereof is appropriately selected. However, from the viewpoint of more stably supporting the rotating shaft, a plurality of dynamic bearing grooves are formed on the bearing surface. It is preferable that they are arranged at equal intervals along the circumferential direction. In the sixth 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.

Further, the dynamic pressure groove 14 shown in the sixth 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 sixth 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 recess formed in the core rod, and the projection is projected. 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. Further, the core rod 32A having the concave portion 32a is press-fitted into the forming hole 30 by using the fifth embodiment shown in FIG.
Even in the case where the bearing is pressed against, the inner diameter surface introduced into the recess 32a of the core rod 32A becomes the bearing surface, so that a bearing in which the middle relief portion is flush with the dynamic pressure groove can be obtained. In addition,
The recess formed in the core rod can be formed by means such as electric discharge machining or electrolytic corrosion.

[0049]

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 (c).

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

FIG. 4 is a longitudinal sectional view showing a manufacturing process of a bearing according to a fourth embodiment of the present invention in the order of (a) and (b).

FIG. 5 is a longitudinal sectional view showing a manufacturing process of a bearing according to a fifth embodiment of the present invention in the order of (a) to (c).

FIGS. 6A to 6C are longitudinal sectional views showing a manufacturing process of a bearing according to a sixth embodiment of the present invention in the order of (a) to (c).

FIG. 7A is a partial perspective view of a core rod used in a sixth embodiment of the present invention, and FIG. 7B is a vertical perspective view showing a part of a bearing manufactured in the sixth embodiment.

[Explanation of symbols]

 1A to 1E: Material 10A to 10F: Bearing body 12: Bearing surface 13: Middle relief portion 14: Dynamic pressure groove 20A to 20F: Bearing 21, 21, A: Housing 30: Forming hole 32, 32A: Core rod 32a: Dynamic pressure groove Convex for forming

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J011 AA20 BA02 CA02 DA01 DA02 5H605 AA08 BB05 CC03 CC04 CC05 DD03 DD05 EA06 EB06 EB13 EB17 EB21 FF03 GG04 GG10 GG12 GG14

Claims (2)

[Claims] 1. A method for manufacturing a bearing, comprising a cylindrical bearing main body incorporated in a cylindrical housing, wherein a cylindrical material molded into the bearing main body is disposed substantially coaxially in the housing. An arranging step; and a press-fitting step of pressing the housing together with the material into a forming hole and press-fitting the material from a state in which a core rod having a uniform outer diameter is inserted into the material arranged in the housing. While crimping to the inside diameter surface of the housing,
At least both ends in the axial direction of the housing are reduced in diameter, and 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 by reducing the diameter of the housing. A method for manufacturing a bearing, comprising forming a middle relief portion between a shaft support surface and a contact portion that does not contact a rotating shaft. 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.