JPH09329146A - Manufacture of bearing with bore groove and bearing unit with bore groove - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a porous bearing unit and its manufacturing method which makes the highly accurate support of rotation possible, and can simply, inexpensively and accurately produce a bearing unit with a bore groove. SOLUTION: A cylindrical bearing material 2A which is about polygonal in an external form and circular in a bore form is prepared, and pressed into a sizing metal mold or a bearing housing 1 using a mandrel. In this case, a bore part corresponding to the outer peripheral large diameter part 2a of the bearing material 2A which is compressed toward an axial center side by the sizing metal mold or the bearing housing 1 is reformed into a circular arc-shape by the mandrel to form the small diameter part 4a of a bearing 2, and the thin thickness part 3b of the bearing material 2A is plastic-deformedly expanded in a direction for leaving an axial center to form a large diameter part 4b being the bore groove of the bearing 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a bearing unit with an inner diameter groove and a bearing unit with an inner diameter groove which are suitable for a motor shaft for rotating a disk at a high speed.

[0002]

2. Description of the Related Art As a bearing for a motor shaft that rotates a disk such as a CD-ROM, MO, HDD, or DVD,
Although ball bearings have been used in the past, sliding bearings are being studied due to the recent trend of cost reduction and the problem of non-periodic runout (NRRO) associated with high speed rotation. Further, in this slide bearing, as a method of forming the inner diameter of the bearing, as described in JP-A-6-109020, the bearing is manufactured to have a perfect inner and outer diameter and is press-fitted into a bearing housing or a case. When fixing, the cut surface is formed in advance on the outer diameter part of the case, and the difference in wall thickness of the case partially changes the rate of reduction of the inner diameter shape in the process of press-fitting the bearing. There is also a case where the inner diameter is deformed corresponding to the cut surface. Further, in Japanese Unexamined Patent Publication No. 8-68423, a virtual inner diameter reference surface is set on the inner diameter surface of a sintered oil-impregnated bearing, and there are three or more concave portions on the outer side and three or more convex portions on the inner side in the circumferential direction. Disclosed is a bearing structure which is continuously formed and generates dynamic pressure by relative rotation with a shaft. To manufacture the bearing, the outer diameter of three or more outer diameter concave portions and the inner diameter of the inner diameter concave portion on the same radius as the outer diameter concave portion are previously provided in the bearing material, and when this bearing material is sizing or press-fitted into the housing, This is a method of press-fitting and deforming to form the above-mentioned inner diameter uneven shape.

[0003]

In the conventional slide bearing described above, it is necessary to make the clearance smaller in order to support the shaft with high accuracy, but the smaller the clearance, the more the fluid resistance of the lubricant is received. There is a problem that the power consumption of the motor and the like increases. For this issue,
Although reducing the viscosity of the lubricant and widening the clearance can be considered as countermeasures, they have contradictory properties and epoch-making countermeasures have been desired. Further, the above-mentioned JP-A-6-10
As described in No. 9020, the inner diameter deformation due to the thickness of the case is
This is just a device for the case, and in the current situation where the motor is downsized, the case may be used as it is as a yoke of the motor, etc., and the flexibility of the case shape is lost, and it is difficult to adopt it. Therefore, countermeasures have been demanded for the bearing itself. The measures must be compact and highly productive.

Further, as a method of forming a concavo-convex shape on the inner diameter of the bearing, a concave portion is previously formed on the outer diameter as described in JP-A-8-68423, and the force for compressing the inner diameter at the time of press-fitting or sizing is used. The forming method has a problem in that it is difficult to control the degree of compression and deformation on the inner diameter surface, and although irregularities can be formed, the inner diameter dimension of the core is not stable. Especially in the case of a bearing mechanism that requires high-precision rotation,
Inner diameter dimensional accuracy of 1 to 2 μm is required, and press fitting margin is 20
Assuming that the inner diameter is reduced to about 10 μm, it is difficult to maintain the inner diameter with high accuracy. Further, in this method, the inner diameter portion supporting the shaft is only a surface reduced from the outer side to the inner side, and it is necessary to make the pores finer in order to support the shaft with high accuracy. There is a concern that the oil supply section will also become finer and oil supply to the inner diameter surface will become insufficient. Moreover, this method requires that the recesses be formed in advance on both the inside diameter and the outside diameter. However, with this material shape, for example, the recesses and protrusions are formed on both the molding die and the core, and the punch is used. However, since it is necessary to provide a corresponding shape and mold in phase, molding becomes complicated and the mold cost increases.

It is an object of the present invention to rationally solve the above problems and to enable highly accurate rotation support, which is simple and inexpensive.
Another object of the present invention is to provide a method of manufacturing a bearing with an inner diameter groove and a bearing unit with an inner diameter groove that can be produced with high precision. Furthermore, other purposes will be clarified one after another in the content described below.

[0006]

The above-mentioned objects are achieved by the following features, which are the most characteristic features of the present invention. First
As described in claim 1 and illustrated in FIG. 1, the invention of claim 1 is a cylindrical bearing material 2 having a substantially polygonal outer shape and a circular inner hole shape.
A is manufactured, and the bearing material 2A is press-fitted into the sizing die or the bearing housing 1 using a mandrel, and at that time, the bearing material is compressed toward the axial center side by the sizing die or the bearing housing 1. A direction in which the inner hole portion corresponding to the outer peripheral large diameter portion 2a of 2A is corrected to an arc shape by the mandrel to form the small diameter portion 4a of the bearing 2 and the thin portion 3b of the bearing material 2A is moved away from the axis. This is a manufacturing method in which the large diameter portion 4b that is the inner diameter groove of the bearing 2 is formed by plastic deformation and bulging. According to a second aspect of the present invention, as described in claim 3 and in FIG. 3, the outer shape is a substantially polygonal shape, and the inner hole shape is a substantially polygonal shape or a large diameter portion 11c at a position corresponding to the outer circumference large diameter portion 11b. A circular cylindrical bearing material 10A having a groove provided at a position corresponding to the outer peripheral large diameter portion 11b is produced, and the cylindrical bearing material 10A is press-fitted into the sizing die or the bearing housing 1 using a mandrel. At that time, the small inner diameter portion 11d of the bearing material 10A is expanded by the mandrel and corrected into an arc shape to reduce the small diameter portion 13a of the bearing 10.
And the thin portion 12b of the bearing material 10A is plastically deformed and bulged in the direction away from the axis to form the large diameter portion 13b that is the inner diameter groove of the bearing 10. According to a third aspect of the present invention, as described in claim 6 and FIG. 5, the outer shape is a substantially polygonal shape, and the inner hole shape is a substantially polygonal shape or a small diameter portion 19d at a position corresponding to the outer peripheral large diameter portion 19a. A cylindrical bearing material 18A having a circular shape with a groove having a groove provided at a position corresponding to the vicinity of the middle connecting the outer peripheral large-diameter portions 19a is produced,
The tubular bearing material 18A is press-fitted into the sizing die or the bearing housing 1 by using a mandrel, and at that time, the small inner diameter portion 19d of the bearing material 18A is expanded by the mandrel and corrected into an arc shape to form the bearing 18 The small diameter portion 21a of the bearing material 18A is formed, and the thin portion 20b of the bearing material 18A is plastically deformed and bulged in the direction away from the axis to form the large diameter portion 21b which is the inner diameter groove of the bearing 18.

From the test results, it is preferable that the first to third inventions satisfy the following condition (1) or (2). (1) In the cylindrical bearing material before the press-fitting, the area of the large-diameter portion (the total of the large-diameter portion 2a of the outer periphery in the example of FIG. 1) of the outer periphery that contacts the inner surface of the sizing die or the bearing housing is
It is 15 to 85% of the area of the entire outer circumference (a virtual circumference passing through the outer circumference large diameter portion 2a in the example of FIG. 1). (2) In the cylindrical bearing material before press fitting, the minimum thickness dimension of the thin wall portion of the bearing material is T (unit is mm, thickness of thin wall portion 3b in the example of FIG. 1), large diameter of bearing material The radius of the part is D
(The unit is mm, and in the example of FIG. 1, the radius connecting the outer peripheral large diameter portion 2a and the shaft center), the radius of the large diameter portion of the inner hole of the bearing material is d (the unit is mm, and in the example of FIG. Radius of hole), where k is the coefficient, T = (D−d) × k, and k = 0.4 to 0.8
It is. And more preferably, the bearing material is D−d = 0.5 to
5 mm, the press-fit margin of the large diameter part of the bearing material is 15-20 μm,
The material is bronze-based or iron-copper-based (about 30 to 55%).

Further, the above object is to provide two or more bearings 27 with the bearing housing 1 as shown in FIG. 7 showing another feature of the present invention.
In the bearing unit 26 with an inner diameter groove, which is press-fitted and fixed on the coaxial line inside and rotatably supports the shaft in each of the bearings 27,
One or more inner diameter grooves 28b are formed in the bearing inner diameter of each bearing 27, and the inner diameter groove 2 of the adjacent bearing 27 is formed.
This is achieved by the fact that 8b are provided in a state in which the phases are shifted in the axial rotation direction, and it becomes possible to rotatably support the shaft of the spindle or the like with high precision.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The main part of the present invention will be described in detail below with reference to the drawings showing an embodiment. In the following embodiment examples, the bearing material used is, for example, bronze-based or iron-copper-based raw material powder mixed and pressure-molded, and then the molded body is fired at a predetermined temperature in a reducing atmosphere. The sintered body itself is an oil-impregnated sintered body which has been subjected to oil-impregnation treatment. Such a sintered body can be obtained by a known manufacturing method, but in the present invention, the shape of the sintered body itself is changed to a bearing housing (may be a sizing die, the same applies hereinafter) to a mandrel. It was devised on the assumption that it would be deformed by press fitting using. Therefore, in the following description, when the bearing material is in a state before being press-fitted into the bearing housing,
It is expressed by adding the symbol A such as A and 6A, and it is expressed as 2, 6 when the product bearing is press-fitted into the bearing housing.

FIG. 1 shows a form corresponding to claim 1, in which 1 (a) is a bearing material 2 before being press-fitted into a bearing housing 1.
FIG. 3B is an end surface shape view of A, and FIG. 3B is an end surface shape view schematically showing the bearing 2 after being press-fitted into the bearing housing 1 (inner diameter is a perfect circle). The cylindrical bearing material 2A of the first embodiment has a substantially triangular outer shape and a circular inner hole shape. Therefore, in the outer circumference of the bearing material 2A, the vicinity of the large diameter portion 2a of the bearing corresponds to the top of the triangle and is a thick portion, and the portions 2b corresponding to the sides of the triangle are thin portions. . That is, each portion 2b is provided in a manner in which the inner side of the locus of the large outer diameter portion 2a is axially lacking, and the thick portion 3b (hereinafter, thin portion 3b) connecting the intermediate portion of each portion 2b and the axial center. Is smaller than a thick portion 3a (hereinafter referred to as a thick portion 3a) connecting the outer peripheral large diameter portion 2a and the shaft center.

The bearing material 2 produced in this way
A is press-fitted into the bearing housing 1 using a mandrel (not shown), and is plastically deformed in the press-fitting process to form a regular bearing 2. In this plastic process, as shown by the arrow in (b), the outer peripheral large diameter portion 2a of the bearing material 2A is compressed by the bearing housing 1 toward the axial center side. At this time, the inner hole portion corresponding to the outer peripheral large diameter portion 2a is corrected to an arc shape by a mandrel to form the small diameter portion 4a of the bearing, and the thin portion 3b of the bearing material 2A is plastically moved in a direction away from the axial center. The large diameter portion 4b of the bearing is formed by deforming and bulging. That is, when the bearing material 2A is press-fitted into the bearing housing 1, the thin wall portion 3b is plastically deformed more strongly than the thick wall portion 3a by the pressing force received from the large outer diameter portion 2a, and the thin wall portion 3b moves toward the non-restraint portion side of the bearing housing 1. Large diameter part 4b of the bearing due to bulging deformation
Therefore, it escapes from the locus of the small-diameter portion 4a (the portion where the shaft S of the motor or the like is engaged in the contact surface state) of the bearing at three locations which are straightened in an arc shape by the mandrel.

FIG. 2 shows an example in which the bearing material of FIG. 1 is modified in accordance with claim 2, FIG. 2 (a) corresponds to FIG. 1 (a), and FIG. 2 (b) corresponds to FIG. 1 (b). It corresponds to. The bearing material 6A of the second embodiment is similar to the embodiment of FIG. 1 in that the vicinity of the outer peripheral large-diameter portion 7a corresponds to the top of the triangle and is a thick portion. By having the missing portion 7b formed in the portion corresponding to the side portion, a plurality of thick-walled portions 7c having the outer peripheral large diameter portion 7a as the apex are provided in a substantially radial shape. In other words, each missing portion 7b is provided in such a manner that the inside of the locus of the outer peripheral diameter large portion 7a is axially missing, and the thick portion 8b connecting each portion 7b and the axial center.
The thin portion 8b (hereinafter referred to as the thin portion 8b) is thinner than the thick portion 8a (hereinafter referred to as the thick portion 8a) that connects the outer peripheral large diameter portion 7a and the shaft center. Further, the bearing material 6A is press-fitted into the bearing housing 1 by using a mandrel (not shown) as in FIG. In this plastic process, as shown by the arrow in (b), the outer peripheral large diameter portion 7a of the bearing material 6A is moved to the bearing housing 1
Then, the corresponding inner hole portion compressed by the axial center side is corrected into an arc shape by the mandrel to form the small diameter portion 9a of the bearing. At the same time, the thin portion 8b is plastically deformed and bulged in the direction away from the axis to form the large diameter portion 9b of the bearing. That is, also in this case, when the bearing material 6A is press-fitted into the bearing housing 1, the thin portion 8b is plastically deformed more strongly than the thick portion 8a by the pressing force received from the large outer diameter portion 7a, and The large diameter portion 9b of the bearing is bulged and deformed toward the restraint portion side, and the small inner diameter portions 4a are corrected in an arc shape by the mandrel (the portion where the shaft S of the motor or the like engages in the contact surface state). Is running away from the trail of.

Therefore, the above-described manufacturing methods have the following advantages. , The small diameter portion 4 of the bearing supports the shaft S indicated by the imaginary line.
a and 9a, and the accuracy of this dimension is important. As for this accuracy, since this portion is straightened at the time of press-fitting using a perfect circular mandrel as in the present invention, the accuracy can be surely and easily imparted. , The inner diameter of the bearing material 2A, 6A corresponding to the thick portions 3a, 8a is corrected by a mandrel to reduce the diameter of the bearing 4a,
Since 9a is formed, the inner diameter surfaces of the small diameter portions 4a, 9a of the bearing have few surface pores. Since the portions of the bearing materials 2A and 6A corresponding to the thick portions 3a and 8a are compressed, they are densified, that is, the density is increased. On the contrary, the portions of the bearing materials 2A and 6A corresponding to the thin-walled portions 3b and 8b are bulged and deformed toward the non-restraint portion side of the bearing housing 1, so that the density does not change so much. That is, the unconstrained portion of the outer diameter portion (the portion corresponding to the thin portion 3b, 8b) corresponds to the large diameter portion 4b, 9b of the bearing that has escaped from the small diameter portion 4a, 9a of the bearing to the outside. Is on the oil supply side to the inner diameter side of the bearing, which is preferable in terms of oil reservoir and dynamic pressure groove action. In this case, since the large diameter portion 9b of each bearing in FIG. 2 is asymmetrical with respect to the large diameter portion 4b of each bearing in FIG. 1, a higher dynamic pressure can be obtained. At the same time, the unconstrained portion of the outer diameter portion (thin portion 3
b, 8b) and the bearing housing 1 and a felt, a porous material, or the like can be arranged in the gap 5 as a refueling mechanism, so that durability performance is particularly high. It is effective for desired applications. The shape of the bearing material of this embodiment is not limited to a specific shape as long as the inner and outer diameters of the bearing housing 1 are true circles.

A further remark will be made regarding the above. Conventionally, the asymmetrical shape of the inner diameter of the bearing is normally forced to be squeezed by a highly accurate mandrel at the time of press fitting, and the shape is taken to be that shape, and the machining accuracy of the mandrel is very important. . However, the mandrel is made of a hard material that is difficult to wear because precision is required for mass production, and it is very difficult to finish this hard material with high precision and in a complicated shape such as an asymmetrical shape. However, there were major problems in terms of cost and reproducibility. On the other hand, according to the configuration of the present invention, the outer diameter portion of the bearing is preliminarily formed into a predetermined shape by a mold, and thereafter, the bearing material is press-fitted into the bearing housing 1 using a normal circular ordinary mandrel. Since a predetermined asymmetrical shape can be obtained only by itself, a highly precise processed mandrel having a complicated shape is not required, and productivity is greatly improved. In addition, an oil replenishing mechanism can be provided on the outer diameter portion of the bearing, and a life extension effect can be expected. Moreover, in addition to the straight line, the missing portion of the outer diameter portion of the bearing material can be various combinations such as a curved line and a composite line.

FIG. 3 shows a form corresponding to claim 3, and FIG. 3 (a) is an end face shape view of the bearing material 10A, and FIG. 3 (b).
[Fig. 3] is an end face shape diagram schematically showing the bearing 10 after being press-fitted into the bearing housing 1 (inner diameter is a perfect circle). The tubular bearing material 10A of the third embodiment has a triangular outer shape, and the inner hole shape is formed in a triangular shape having a large-diameter portion 11c at a position corresponding to the outer-diameter large-diameter portion 11a. Therefore, in this outer circumference, the vicinity of the large outer diameter portion 11a corresponds to the apex of the triangle, and the side portions 11b connecting the large outer diameter portions 11a correspond to the respective side portions of the triangle. On the other hand, the inner circumference is
The inner peripheral large diameter portion 11c is located directly below the outer peripheral large diameter portion 11a, and the side portion (corresponding to the small inner diameter portion) 11d connecting the inner peripheral large diameter portions 11c is located directly below the side portion 11b. There is. In addition, the thick portion 1 between the both side portions 11b and 11d
2b (hereinafter referred to as thin portion 12b) is the outer / inner peripheral large diameter portion 1
A thick portion 12a (hereinafter, thick portion 1
2a).

The manufactured bearing material 10A is press-fitted into the bearing housing 1 using a mandrel (not shown), and is plastically deformed during the press-fitting process to form the regular bearing 1.
0 is formed. In this plastic process, as shown by the arrow in (b), the side portion 11d which is the small inner diameter portion of the bearing material 10A.
While expanding with the mandrel to correct the arc shape,
The thin portion 12d is plastically deformed and bulged in the direction away from the axis. In other words, the bearing material 10A is replaced by the bearing housing 1
At the time of press fitting into the inside, the thin portion 12b receives a strong deforming force from the mandrel and thick portion 12a sides and bulges and deforms to the non-restraint portion side of the bearing housing 1, and at the same time, the mandrel corrects the arc shape. The small diameter portion 13a of the bearing (the portion where the shaft S of the motor or the like engages in the contact surface state) is formed at three places, and the large diameter portion 11c of the inner circumference of the bearing material 10A is the large diameter portion 1 of the bearing.
3b is formed. In the process of press-fitting the bearing material 10A, the outer diameter of the large diameter portion 11a is reduced. However, in this case, the inner diameter of the large diameter portion 11c is larger than the reduction amount of the inner diameter. The portion to be formed is the large diameter portion 13b of the bearing.

FIG. 4 shows an example in which the bearing material of FIG. 3 is modified in accordance with claim 4, the same (a) corresponds to FIG. 3 (a), and the same (b) corresponds to FIG. 3 (b). It corresponds. In the bearing material 14A of the fourth embodiment, the outer shape is triangular and the inner hole shape is formed in a triangular shape in which the position corresponding to the outer peripheral large diameter portion 15a is the inner diameter large diameter portion 15c as compared with the configuration of FIG. The same applies to the points described above, but by having the missing portion 15b formed in the portion corresponding to each side of the outer peripheral triangle,
A plurality of thick-walled portions 15f having the outer peripheral large-diameter portion 15a as the top are provided in a substantially radial shape. Therefore, the outer circumference is formed by the outer circumference large diameter portion 15a and the missing portion 15b, while the inner circumference has the inner circumference large diameter portion 15c located directly below the outer circumference large diameter portion 15a. A side portion (corresponding to a small inner diameter portion) 15d connecting the portions 15c is located directly below the missing portion 15b. Further, a thick portion 16b (hereinafter referred to as a thin portion 16b) between the missing portion 15b and the side portion 15d is a thick portion 16a between the outer / inner peripheral large diameter portions 15a, 15c.
It is thinner than (hereinafter referred to as the thick portion 16a). Also in this case, similarly to FIG. 3, the bearing material 14A is plastically deformed to form the regular bearing 14 in the process of being press-fitted into the bearing housing 1 using a mandrel (not shown). That is, the bearing material 14A is expanded by the mandrel at the side portion 15d having a small inner diameter to be corrected into an arc shape, and at the same time, the thin portion 16d is plastically deformed and expanded in a direction away from the axial center. As a result, the thin portion 16b receives a strong deforming force from the mandrel and thick portion 16a sides and bulges and deforms toward the non-restraint portion side of the bearing housing 1, and at the same time, the small diameter portion of the bearing straightened into an arc shape by the mandrel. 17a (a portion where the shaft S of the motor or the like engages in the contact surface state) is formed at three places, and the large diameter portion 15c of the inner circumference corresponding to the top of the triangle is formed.
Form the large diameter portion 17b of the bearing.

Each of the above-mentioned configurations has the following features in addition to the advantages (1) to (3) described in paragraph 0013. In addition,
In the case of FIG. 4, similarly to the embodiment of FIG. 2, the large diameter portion 17b of each bearing of FIG. 4 is asymmetrical with respect to the large diameter portion 13b of each bearing of FIG. 3, so that a higher dynamic pressure can be obtained. , Small diameter parts 13a, 17 of the bearing formed by the mandrel
a is the thick parts 12a, 16a of the bearing materials 10A, 14A
Side portions 11d, 1 that are smaller in inner diameter and are thinner than
Since it is bulged and deformed from the 5d side, the pores become relatively rough, which is suitable when crushing is not desired. The supporting portions of the shaft S are the small diameter portions 13a and 17a of the bearing, and since these portions do not correspond to the press-fitted portions with respect to the housing 1, the bearing performance is not easily affected by the temporal change of the bearing housing material. Becomes This point will be added below. In the conventional configuration, for example, in the case of a zinc alloy die-cast bearing housing to reduce weight and cost, the case may change with time due to creep after press fitting of the bearing. The small portion is also affected by the influence (the inner diameter increases with the lapse of time), and there is a problem that the absolute value of the dimension changes, but this is extremely effective as a solution to such a problem. In other words, the press-fitting portion (outer peripheral large diameter portion 11a, 15
In (a), the influence is directly exerted, whereas in the non-press-fitted portions (side portions 11b, 15b which are small inner diameter portions), the influence is hard to exert. Therefore, in the non-press-fitted portions, the small diameter portions 13a, 17a of the bearing are used.
By forming the above, it is possible to obtain the bearings 10 and 14 in which the inner diameter is less likely to change with time. This makes it possible to omit the step which has been conventionally performed, such as leaving it until the dimensions after the press-fitting are stable, and the productivity can be improved.

The bearing material 10A having such a shape,
14A can be easily obtained by forming a cylindrical material and pressing the material from a plurality of outer diameter directions to plastically deform the material. Further, in each of these embodiments, the cylindrical bearing materials 10A and 14A have a triangular outer shape, and the inner hole shape corresponds to the outer peripheral large diameter portions 11a and 15a at positions corresponding to the large inner diameter portion 1a.
Although the case of forming the triangular shapes 1c and 15c has been described, it is also possible to use a grooved circular shape having a groove at a position corresponding to the outer peripheral large diameter portions 11a and 15a. .

5A and 5B show a form corresponding to claim 6, FIG. 5A is an end face shape view of the bearing material 18A, and FIG. 5B is the bearing 18 after being press-fitted into the bearing housing 1 (inner diameter is a perfect circle). It is an end face shape figure which shows typically. The tubular bearing material 18A of the fifth embodiment has a triangular outer shape, and the inner hole shape is formed in a triangular shape in which the position corresponding to the outer peripheral large diameter portion 19a is the inner peripheral small diameter portion 19d. Therefore, this circumference is
The vicinity of the outer peripheral large diameter portion 19a corresponds to the top of the triangle, and the side portion 19b connecting the outer peripheral large diameter portions 19a corresponds to each side of the triangle. On the other hand, in the inner circumference, the inner circumference large diameter portion 19c is located directly below the middle of the side portion 19b, and the inner circumference small diameter portion 19d is located directly below the outer circumference large diameter portion 19a. In addition, the side portion 19b and the inner peripheral large diameter portion 1
The thick portion 20b between 9c (hereinafter referred to as the thin portion 20b) is thinner than the thick portion 20a (hereinafter referred to as the thick portion 20a) between the outer peripheral large diameter portion 19a and the small inner peripheral diameter portion 19d. Has become.

The manufactured bearing material 18A is press-fitted into the bearing housing 1 using a mandrel (not shown), and is plastically deformed in the press-fitting process to form a regular bearing 18. In this plastic process, as indicated by the arrow in (b),
The inner peripheral small-diameter portion 19d of the bearing material 18A is expanded by the mandrel to correct it into an arc shape, and the thin-walled portion 20d is plastically deformed and bulged in a direction away from the axial center. In other words, when the bearing material 18A is press-fitted into the bearing housing 1, the thin portion 20b receives a strong deforming force from the mandrel side and bulges and deforms toward the restraining portion side of the bearing housing 1, and at the same time, the thin mandrel has an arc shape. Small diameter portion 21a of the bearing straightened (a portion where the shaft S of the motor or the like engages in the contact surface state)
Is formed in three places, and the large diameter portion 19c of the inner circumference corresponding to the top of the triangle forms the large diameter portion 21b which is the inner diameter groove of the bearing.

FIG. 6 shows an example in which the bearing material of FIG. 5 is modified in accordance with claim 7, the same (a) corresponds to FIG. 5 (a), and the same (b) corresponds to FIG. 5 (b). It corresponds. The bearing material 22A of the sixth embodiment has a triangular outer shape, and the inner hole shape is a triangular shape in which the inner peripheral small diameter portion 23d is located at a position corresponding to the outer peripheral large diameter portion 23a. However, since the outer peripheral large-diameter portion 23a has a plurality of thickened portions 23f, the plurality of thick-walled portions 23f are formed substantially in the outer peripheral large-diameter portion 23a. It is provided radially. Therefore, while this outer periphery is formed by the outer periphery large diameter portion 23a and the missing portion 23b,
In the inner circumference, the large diameter portion 23c of the inner circumference is located directly below the missing portion 23b, and the small diameter portion 23d of the inner circumference is located directly below the large diameter portion 23a of the outer circumference. Further, a thick portion 24b (hereinafter, referred to as a thin portion 24b) between the missing portion 23b and the inner peripheral large diameter portion 23c is a thick portion 24a (hereinafter, referred to as a thin portion 24a) between the outer peripheral large diameter portion 23a and the inner peripheral small diameter portion 23d. It is thinner than the thick portion 24a). Also in this case, similarly to FIG. 5, in the process of press-fitting the bearing material 22A into the bearing housing 1 using a mandrel (not shown), the bearing material 22A is plastically deformed to form the regular bearing 22. In this plastic process, as shown by the arrow (b), the small inner peripheral diameter portion 23d of the bearing material 22A is expanded by the mandrel to correct it into an arc shape, and the thin portion 24
Plastic deformation swells in a direction away from d. In other words, when the bearing material 22A is press-fitted into the bearing housing 1, the thin portion 24b receives a strong deforming force from the mandrel side and bulges and deforms toward the restraining portion side of the bearing housing 1, and at the same time, the thin mandrel has an arc shape. The small diameter portion 25a (the portion where the shaft S of the motor or the like is engaged in the contact surface state) is formed in three places, and the large inner diameter portion 23c corresponding to the top of the triangle is formed in the bearing. The large-diameter portion 25b is formed.

Each of the above constructions has the following features in addition to the advantages (1) to (3) described in paragraph 0013. The supporting portion of the shaft S is the small diameter portions 21a and 25a of the bearing, and these portions are pressed from the large outer diameter portions 19a and 23a and the small inner diameter portions 19d and 23d to be densified and have few inner surface pores. Will be things. On the contrary, the large inner diameter portion 21
Since b and 25b have almost no change in density and are not affected by the mandrel, they are maintained in a state with a large amount of pores. In the case of FIG. 6, similarly to the embodiment of FIG. 2, each inner diameter large portion 25b of FIG. 6 is asymmetrical to each inner diameter large portion 21b of FIG. 5, so a higher dynamic pressure is obtained. . Further, in each of these forms, the cylindrical bearing materials 18A and 22A have a triangular outer shape, and the inner hole shape is a triangular shape in which the positions corresponding to the outer peripheral large diameter portions 19a and 23a are the inner peripheral small diameter portions 19d and 23d. Although the case where the inner hole is formed in a circular shape with grooves provided at the positions corresponding to the outer peripheral large diameter portions 19a and 23a is also possible.

Next, a seventh mode of the present invention will be described with reference to FIG. The seventh mode is an improved technique in which a plurality of bearings are press-fitted and fixed in the bearing housing, unlike the above-described modes. Here, an example is shown in which two bearings 27 are used, but the same configuration can be applied when three or more bearings are press-fitted, and the bearing material before press-fitting is used in the above-described manufacturing method. The shape is preferable, but the shape may be further modified.

FIG. 7 (a) is a view in which the bearing unit 26 with an inner diameter groove of the present invention is axially sectioned, and FIG. 7 (b) is a view seen from the end face side. The bearing unit 26 has bearings 27, 27 that are press-fitted on both sides inside the bearing housing 1. Each of the bearings 27 is formed by applying the above-described method of the present invention, and is the same in that the small diameter portion 28a of the bearing and the large diameter portion 28b of the bearing are formed at three locations. However, in the bearing housing 1, the phases of the large diameter portions 28b, 28b of the bearings 27, 27 are shifted by a predetermined angle. More specifically,
In this embodiment, each of the bearings 27 has a large diameter portion 28b of the bearing formed at intervals of about 120 degrees on the inner circumference. When press-fitting into the bearing housing 1, the bearing 27 on the right side is shown against the bearing 27 on the right side. As shown in FIG. 7 (b), they are press-fitted and fixed at positions shifted by 60 degrees. Therefore, the phase of the large diameter portion 28b of each bearing of both bearings 27, 27 is shifted by 60 degrees. As a result, as the bearing unit 26, in the upper and lower or left and right bearings 27, 27, the small diameter portions 28a, 28 of the bearings are formed.
a (sliding portion that supports the shaft S) and the large diameter portion 28 of the bearing
b and 28b are formed at 3 places on the upper side, 3 places on the lower side, and 6 places at intervals of 60 degrees in total. Apparently,
It has the same effect as a bearing by generating dynamic pressure at 6 locations.

Incidentally, if six dynamic pressure portions are simply formed as in the conventional bearing, the dynamic pressure must be generated within the range of 60 degrees, and the dynamic pressure has a width as large as possible. The more stable and large dynamic pressure can be obtained, but the range is narrowed and the dynamic pressure generated is limited. Therefore, the number of dynamic pressure generating parts has been limited so far by the inner diameter size and the number of rotations. However, such constraints are overcome by this invention. That is, as described above, the bearings 27 to be press-fitted into the bearing housing 1 are composed of two or more, and the respective bearings 27, 27 are shifted by a predetermined angle to be press-fitted into different phases to be divided into individual bearings 27, 27. By providing the dynamic pressure portions (large diameter portions 28b, 28b which are the inner diameter grooves of the bearing), it becomes possible to easily form a large number of dynamic pressure portions while ensuring the width.

Therefore, the bearing unit 26 with an inner diameter groove of the present invention has a large number of dynamic pressure portions (bearing large diameter portions 28b, 28).
By b), a stable large dynamic pressure can be obtained, and it becomes possible to provide a bearing that suppresses shaft runout even at high speed rotation and suppresses an increase in friction torque. Top and bottom or left and right bearings 27, 27
The inner diameter of the bearing has a large diameter portion 28b of the bearing for generating dynamic pressure.
In addition to 28b, the same effect can be obtained in FIGS. 1 to 6 described above, and the bearings can be set in different shapes, and the phase angle between the bearings can be arbitrarily set.

[0028]

As described above, according to the present invention,
Conventionally, in order to make the inner diameter shape of the bearing complicated,
A mold jig such as a mandrel with a corresponding shape and high accuracy was required, and as a bearing that supports high-speed rotation, more accurate rotation support is required, and a complicated inner diameter shape is required. In view of the above, it is possible to form a complicated inner diameter shape with a relatively simple bearing material, and it is possible to provide a manufacturing method and a bearing unit that are excellent in mass production. In particular, the present invention can produce a complicated shape easily, inexpensively, and accurately. Also, by shifting the dynamic pressure generation points of each bearing, the dynamic pressure part (large diameter part or groove part of the bearing), which has a limit in one bearing, can be dispersed, so that better and more accurate rotation support can be achieved. Is possible.

[Brief description of drawings]

FIG. 1 is an end view of a bearing shown as a first embodiment of the present invention and a schematic end view after press fitting.

FIG. 2 is a diagram showing a modified example of the first embodiment in a similar manner.

FIG. 3 is a diagram showing a third embodiment of the present invention in the same manner as in FIG.

FIG. 4 is a diagram showing a modified example of the third embodiment in a similar manner.

FIG. 5 is a diagram showing a fifth mode of the present invention in the same manner as in FIG.

FIG. 6 is a diagram showing a modified example of the fifth embodiment in a manner similar to FIG.

FIG. 7 is a sectional view and an end view of a bearing unit structure shown as a seventh embodiment of the present invention.

[Explanation of symbols]

2A, 6A, 10A, 14A, 18A, 22A is a bearing material 2,6,10,14,18,22,27 is a bearing 4a, 9a, 13a, 17a is a small diameter portion 21a, 25a, 26a, 28a of the bearing Small diameter part of bearing 4b, 9b, 13b, 17b is large diameter part of bearing (inner diameter groove) 21b, 25b, 26b, 28b is large diameter part of bearing (inner diameter groove) 26 is bearing unit S is shaft

Claims (8)

[Claims] 1. A cylindrical bearing material having a substantially polygonal outer shape and a circular inner hole shape is produced, and the bearing material is press-fitted into a sizing die or a bearing housing by using a mandrel. , The inner hole portion corresponding to the outer peripheral large diameter portion of the bearing material compressed toward the axial center side by the sizing die or the bearing housing is corrected to an arc shape by the mandrel to form a small diameter portion of the bearing. A method of manufacturing a bearing with an inner diameter groove, characterized in that the thin portion of the bearing material is plastically deformed and expanded in a direction away from the shaft center to form a large diameter portion that is an inner diameter groove of the bearing. 2. The cylindrical bearing material before press-fitting has a plurality of wall thicknesses having the outer peripheral large diameter portion as a top by forming a cutout portion on each side of the outer peripheral portion except near the outer peripheral large diameter portion. The method for manufacturing an inner diameter grooved bearing according to claim 1, wherein the portions are provided in a substantially radial shape. 3. A groove having a substantially polygonal outer shape and a groove formed at a position corresponding to the outer peripheral large-diameter portion or a substantially polygonal shape having a large-diameter portion corresponding to the outer peripheral large-diameter portion. The tubular bearing material is manufactured by press-fitting the tubular bearing material into a sizing die or a bearing housing using a mandrel, and at that time, a small inner diameter portion of the bearing material is expanded by the mandrel to form a circle. It is characterized by forming a small diameter portion of the bearing by correcting it in an arc shape and plastically bulging the thin portion of the bearing material in a direction away from the shaft center to form a large diameter portion that is an inner diameter groove of the bearing. Manufacturing method of bearing with internal groove. 4. The cylindrical bearing material before press-fitting has a plurality of wall thicknesses having the outer peripheral large diameter portion as a top by forming a cutout portion on each side of the outer peripheral portion excluding the vicinity of the outer peripheral large diameter portion. The method for manufacturing an inner diameter grooved bearing according to claim 3, wherein the portions are provided in a substantially radial shape. 5. The bearing with inner diameter groove according to claim 3, wherein the cylindrical bearing material before press-fitting is formed by pressing a cylindrical material from a plurality of outer diameter directions and plastically deforming the material. Production method. 6. A groove is provided at a position corresponding to a substantially polygonal shape having an outer shape of a substantially polygonal shape and an inner hole shape having a smaller diameter portion at a position corresponding to the outer peripheral large diameter portion, or a position near an intermediate portion connecting the outer peripheral large diameter portions. A tubular bearing material having a circular shape with a groove is prepared, and the tubular bearing material is press-fitted into a sizing die or a bearing housing using a mandrel, in which case the small inner diameter portion of the bearing material is Expands with a mandrel and corrects it into an arc shape to form a small diameter part of the bearing, and at the same time forms the large diameter part that is the inner diameter groove of the bearing by plastically bulging the thin part of the bearing material in the direction away from the axis A method for manufacturing a bearing with an inner diameter groove, comprising: 7. The cylindrical bearing material before press-fitting has a plurality of wall thicknesses having the outer peripheral large diameter portion as a top by forming a cutout portion on each side of the outer peripheral portion except near the outer peripheral large diameter portion. The method for manufacturing a bearing with an inner diameter groove according to claim 6, wherein the portions are provided substantially radially. 8. A bearing unit in which two or more bearings are press-fitted and fixed on a coaxial line in a bearing housing and a shaft is rotatably supported by each of the bearings, and one or more inner diameter grooves are provided in a bearing inner diameter of each of the bearings. A bearing unit with an inner diameter groove, characterized in that the inner diameter grooves of the respective bearings that are respectively formed and are adjacent to each other are provided in a state of being out of phase in the axial rotation direction.