JPH1122731A - Porous composite bearing and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve bearing performance by a method wherein a dynamic pressure is apt to be generated and the dynamic pressure is increased to a high value. SOLUTION: Two bearing bodies 10 and 20 made of a sintered alloy are axially joined together for combination such that bearing holes 13 and 23 in which a rotary shaft is inserted are continuously interconnected. Opening recessed parts 15 and 25 in a triangle shape opened to joints 11 and 21 are formed in both the inner peripheral surfaces 14 and 24 of bearing bodies 10 and 20. When the bearing bodies are joined together, the opening recessed parts 15 and 15 are mated together to form a triangular closed recessed part 4 in the inner peripheral surface 3 of the whole of a bearing 1. The closed recessed part 4 has a sectional area gradually decreased in the rotation direction of the rotary shaft. By concentrating lubrication oil to an end part, a high dynamic pressure is always generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous composite bearing for supporting a rotary shaft, and more particularly to a rotary shaft rotating at a relatively high speed, such as a bearing for a spindle motor incorporated in information equipment, audio-visual equipment, and the like. The present invention relates to a porous composite bearing which is suitable for supporting the bearing with high accuracy.

[0002]

2. Description of the Related Art In a bearing for supporting a rotary shaft, noise and vibration are generated due to friction generated by sliding with the rotary shaft. In particular, the bearing such as the spindle motor bearing described above rotates at a relatively high speed. When the rotating shaft is supported with high precision, it is necessary to minimize noise and vibration. As such a bearing, there is (1) one in which a plurality of grooves extending in the circumferential direction are formed on an inner peripheral surface to reduce frictional resistance. This bearing is made of an oil-impregnated sintered alloy that is a porous material, and lubricating oil accumulated in the groove is supplied to the sliding surface with the rotation of the rotating shaft to form an oil film. This oil film forming action and the reduction of the friction area due to the formation of the groove are combined, so that the frictional resistance is reduced, and noise and vibration are suppressed.

[0003] As described above, a bearing made of a porous sintered alloy, having a groove formed in the inner peripheral surface thereof and effectively reducing the frictional resistance by effectively flowing the lubricating oil in the groove, includes: For example, (2) a groove having a spiral shape to guide lubricating oil inward of the bearing with the rotation of the rotating shaft; (3) one end of the spiral groove is open at the end face and is directed toward the closed other end. And (4) a groove in which the developed shape of the inner peripheral surface is V-shaped so that the lubricating oil is concentrated at the center of the bearing in the axial direction.

[0004]

However, in the above-described bearing, as the rotating shaft rotates and the lubricating oil in the groove flows, the pressure of the lubricating oil increases and so-called dynamic pressure is generated. The dynamic pressure acts to support a part of the load on the rotating shaft. In such a dynamic pressure bearing, the higher the dynamic pressure, the higher the rigidity of the bearing.However, in the case of a sintered alloy bearing, the lubricating oil leaks due to the porosity, and the dynamic pressure increases. And it is difficult to obtain a large dynamic pressure. Therefore, the shape of the groove in which the lubricating oil accumulates becomes important in order to secure the dynamic pressure. However, the grooves such as (1), (2), and (3) above are
Since both ends are open to the end face of the bearing, even if the pressure of the lubricating oil increases, the pressure leaks immediately on the opening side, that is, toward the end on the low pressure side, and a sufficient dynamic pressure cannot be obtained. In the case of the V-shaped groove described in (4) above, the lubricating oil concentrates on the bent portion of the groove, so that dynamic pressure is easily generated. However, in the case of forming a V-shaped groove, it is difficult to mold the die, so that after sintering, the sintered body needs to be subjected to post-processing by cutting or rolling. Although sintered products do not require such post-processing, they have the major advantage that they can reduce costs.However, the need for post-processing reduces the meaning of manufacturing by sintering and increases costs. Invite.

On the other hand, as for the longitudinal cross-sectional shape of the groove, for example, the depth of the groove along the circumferential direction becomes gradually shallower in the direction of rotation of the rotating shaft, and its tip smoothly continues to the inner peripheral surface. Wedge-shaped shapes are also conceivable. However, in this case, although a high dynamic pressure can be obtained, since the groove is closed at both ends in the inner peripheral surface, it is difficult to form the groove by the die molding method as described above, and it is necessary to rely on post-processing. .

[0006] In the technique of enlarging the inner diameter, so-called "medium inflation", a groove or a recess which is not open at the end face can be formed on the inner peripheral face, but this reduces the sliding area with the rotating shaft. The purpose is to increase the coaxial accuracy and to increase the coaxial accuracy, and almost no dynamic pressure is generated.

Therefore, according to the present invention, not only the frictional resistance is reduced and noise and vibration are suppressed, but also dynamic pressure is easily generated while being porous, and the dynamic pressure is large. It is an object of the present invention to provide a porous composite bearing whose rigidity is improved as a bearing and a method of manufacturing the same.

[0008]

A porous composite bearing according to the present invention is assembled by joining at least two or more porous bearing bodies containing a fluid lubricant in an axial direction so as to be continuous with each other. An inner peripheral surface of at least one of the bearing bodies joined to each other is formed with an opening recessed at at least one end surface side joining surface, thereby forming an inner peripheral surface of the entire combined bearing. It is characterized in that a closed recess whose peripheral edge is closed in the rotation direction is formed in the inside. In the case of this porous composite bearing, when an opening recess is formed only on the inner peripheral surface of one bearing body, the opening recess is open to the joint surface, so that the bearing body is pressure molded. In this case, the degree of freedom of the shape of the opening concave portion is high, and the opening concave portion can be easily formed. When the bearing body is joined to form a bearing, the opening of the opening recess is closed by the joint surface of the bearing body where the opening recess is not formed, so that the opening recess becomes a closed recess. Since the lubricating oil supplied to the closed recess has no escape area, dynamic pressure is easily generated, and the rigidity of the bearing is improved.

Here, it is also possible to form the closed recesses by forming the open recesses on the inner peripheral surfaces of the two bearing bodies joined to each other, and abutting the openings of these open recesses. When the opening recess is formed in only one bearing body, the opening recess becomes the closing recess as it is. By combining both the opening recesses, the degree of freedom of the shape of the closing recess is further increased. In the case where the opening recess penetrates in the axial direction and opens at the joint surfaces at both ends, the same effect can be obtained by abutting the joint surfaces having a large opening amount. Also, if the longitudinal cross-sectional area of the closed recess is changed by decreasing the width or decreasing the depth toward the rotation direction of the rotating shaft, the side with the reduced cross-sectional area becomes a wedge-shaped gap, A high dynamic pressure is quickly generated, and a stable shaft supporting action is exhibited, especially at the initial startup of the rotating shaft. In addition, the air permeability of each bearing body and / or
Alternatively, if the porosity is made different, the lubricant moves by capillary force to the smaller air permeability and / or porosity. Therefore, by setting a bearing portion, which is a severe condition, on the moving side, the overall life is extended. Is achieved.

Further, when a clearance recess deeper than the opening recess is formed on at least one joint surface of the inner circumferential surface of the bearing, lubricant is always supplied from the clearance recess to the closing recess, and the lubricating action is maintained. Is done. In this way, as means for positively supplying the lubricating oil, for example, if the bearing inner diameter is changed so that the lubricant is supplied to the smaller diameter side,
The contained lubricant is used effectively to extend the life. If the inner diameter of the bearing and the outer diameter of the shaft on the side where the load is high are made large, the surface pressure applied to the sliding surface can be reduced.
Further, by making the inner surface of the closed concave portion higher in density than the other portions, the leakage of the dynamic pressure is suppressed, and the high dynamic pressure is held. Furthermore, if a convex portion protruding in the axial direction is formed in advance on the joint surface on the side of the opening concave portion, and the convex portions are pressurized at the time of recompression, the bearing bodies are brought into close contact with each other,
The density of the joints of the closed recesses is increased, and the leakage of dynamic pressure from the boundary is suppressed.

Further, the present invention provides a method of manufacturing the above-mentioned porous composite bearing, in which each of the above-mentioned bearing bodies is formed from a porous material, and then the bearing surfaces are joined together in a state where these bearing bodies are continuous to be recompressed. At the time of the recompression, each of the bearing bodies is pressurized in the axial direction so as to be closely adhered to each other, and a closed recess is formed. According to this manufacturing method, a porous composite bearing having a closed concave portion that is completely or partially closed in the inner peripheral surface can be easily manufactured. In addition, a convex portion projecting in the axial direction is formed in advance on the joint surface on the side of the opening concave portion, and the convex portion is pressurized at the time of the recompression to bring the bearing bodies into close contact with each other. The density is increased and the leakage of dynamic pressure from the boundary is suppressed. Furthermore, if the processing allowance of the closed concave portion is increased to increase the density of the inner surface of the closed concave portion, the degree of processing is increased, whereby the air permeability and / or the porosity is reduced, and the leakage of the dynamic pressure is suppressed. Large dynamic pressure is maintained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a state in which the bearing 1 of the first embodiment is split vertically in the radial direction. This bearing 1 is composed of first and second bearing bodies 10 and 20 that divide the axial direction. It is configured. Each of the bearing bodies 10 and 20 is made of a sintered alloy which is a porous body. First, a raw material powder is pressed and molded by a molding die to form a green compact, and then the green compact is sintered. You get by doing. And these two bearing bodies 10,
20 is pressed in the axial direction in a recompression (sizing) step, and the two are joined to obtain the bearing 1. In addition, not only the first embodiment but also all the bearings of each embodiment described below are formed by joining a plurality of bearing bodies made of a sintered alloy in the axial direction. I do.

The first and second bearing bodies 10 and 20 are
Each of them is formed in a ring shape and has a joint surface 1
Step parts 12 and 22 which fit each other are formed in 1 and 21. The fitting of these steps 12, 22 ensures that they are connected. In addition, a plurality (only one is shown in the figure) of a right-angled triangular opening concave portion 15, 25 is formed in the inner peripheral surfaces 14, 24 of the bearing holes 13, 23 of these bearing bodies 10, 20 with good balance in the circumferential direction. Have been. One of the right-angled sides of each of the opening concave portions 15 and 25 has a joint surface 11 or 2.
1 and the other side extends in the axial direction. These opening concave portions 15 and 25 are formed in advance at the time of compacting. When molding the green compact, the opening recess 15 is formed on the outer peripheral surface.
A core having a convex portion conforming to the shape of (25) is used, but since the opening concave portion 15 (25) is open in the axial direction, the lower punch for molding is moved upward with respect to the die and the core. The green compact can be taken out of the mold simply by moving it relatively. As shown in FIG. 2, the cross-sectional shape of each of the opening recesses 15 and 25 in the radial direction is deepest at the center in the circumferential direction, gradually becomes shallower toward both ends in the circumferential direction, and gradually becomes smaller. It has a valley shape that continues to 24. And, each of these bearing bodies 10, 20
Means that the step portions 12 and 22 are fitted together and the joining surface 1
The bearings 1 and 21 are brought into close contact with each other and assembled into the bearing 1.
In the state where the bearing 1 is used, the bearing holes 1 of the bearing bodies 10 and 20 are formed.
3, 23 are coaxially continuous, and furthermore, the opening recesses 15, 2
5, a plurality of triangular closing recesses 4 whose peripheral edges are closed in the inner peripheral surface 3 of the bearing hole 2 of the entire bearing 1,
It is formed with good balance in the circumferential direction. Note that the cross section of the closed concave portion 4, that is, the open concave portions 15 and 25 may have a shape that gradually becomes shallower toward one side (right side in the figure) in the circumferential direction as shown in FIG.

FIGS. 4 and 5 show a modification of the first embodiment. As shown in FIG. 4, on the inner peripheral side of the joint surface 11 of the first bearing body 10, a circumferential ridge 16 is further provided.
Are formed. In addition, concave and convex portions (not shown) for positioning that mesh with each other are formed on the opposing surfaces 12a and 22a on the outer peripheral side of the step portions 12 and 22. When the first and second bearing bodies 10 and 20 are joined, the concave portions 15 and 25 are positioned by engaging these concave and convex portions. When the first and second bearing bodies 10 and 20 are joined, the circumferential ridge 16 of the first bearing body 10 is largely plastically deformed and crushed to obtain the bearing 1 shown in FIG. As a result, the joint portion has a high density, the leakage of the dynamic pressure from the boundary at the joint portion is suppressed, the dynamic pressure further increases, and the bearing performance is improved.

Next, second to fourth embodiments in which the shape of the closed recess formed on the inner peripheral surface of the bearing hole is changed will be described. These embodiments are the same as the first embodiment in that the first and second bearing bodies 10 and 20 are joined.

(2) Second Embodiment In the bearing 1 of the second embodiment shown in FIG.
A plurality of (only one is shown in the figure) short recesses 15 and 25 in the form of short helical grooves are formed on the inner peripheral surfaces 14 and 24 of the second bearing bodies 10 and 20, respectively, in the joint surfaces 11 and 21 with good balance. Is formed. Each of the bearing bodies 10 and 20 is joined, and the openings of the opening recesses 15 and 25 abut against each other, so that a plurality of V-shaped closing recesses 4 are formed in a circumferential direction with good balance. The cross-sectional shape along the radial direction of the opening concave portions 15 and 25 is rectangular as shown in FIG. 7, and the depth is substantially uniform. Note that the depth may be non-uniform such that the depth decreases toward both ends in the circumferential direction. When the green compact of the bearing 1 is formed, a core having a convex portion conforming to the shape of the opening concave portion 15 (25) is used on the outer peripheral surface, but the opening concave portion 15 (25) is spirally formed in the axial direction. The lower punch for forming is relatively moved upward with respect to the die and the core as in the case of forming the helical gear, and at the same time, the core is opened.
The green compact can be taken out of the mold by rotating along 5).

(3) Third Embodiment In the bearing 1 according to a third embodiment shown in FIG.
In the inner peripheral surfaces 14 and 24 of the second bearing bodies 10 and 20, a plurality of right-angled triangular opening recesses 1 opening to the joint surfaces 11 and 21.
5, 25 are formed in the circumferential direction with good balance. In these opening concave portions 15 and 25, sides orthogonal to the bottom side on the opening side are along the axial direction. When the bearings 10 and 20 are joined and the opening recesses 15 and 25 are united, a plurality of closed recesses 4 whose peripheral edges are closed in the inner peripheral surface 3 of the entire bearing 1 are balanced in the circumferential direction. Is formed. These closed recesses 4 are parallelograms in which the oblique sides and the sides are parallel and symmetric with respect to a point, and have a constant axial length. In the case of this shape, the dynamic pressure effect of the closed concave portion 4 accompanying the rotation of the rotating shaft is exerted in substantially the same manner in either the forward or reverse rotation direction, and the degree of freedom of application is increased.

(4) Fourth Embodiment In a bearing 1 according to a fourth embodiment shown in FIG. 9, a plurality of parts similar to those of the third embodiment are provided on an inner peripheral surface 14 of a first bearing body 10. The opening recess 15 is formed in the circumferential direction with good balance, while a plurality of trapezoidal opening recesses 25 whose upper and lower bottoms are parallel to the axial direction are formed on the inner peripheral surface 24 of the second bearing body 20. It is formed in a well-balanced direction. Then, the bearing bodies 10 and 20 are joined to form the opening recesses 15 and 2.
As a result, the closed recesses 4 whose peripheral edges are closed in the inner peripheral surface 3 of the entire bearing 1 are formed in the circumferential direction with good balance. These closed recesses 4 have a trapezoidal shape whose axial length becomes shorter as going in the circumferential direction indicated by arrow A.

Now, in each of the bearings 1 of the first to fourth embodiments, the first and second bearing bodies 1 constituting the bearing 1 are described.
The opening recesses 15 and 25 formed in the bearing bodies 10 and 20 are formed in the joining surfaces 11 and 21 respectively.
Of the opening recesses 15 and 2 when the
5 can be easily formed. Then, by combining these opening concave portions 15 and 25, it is possible to easily form the closed concave portion 4 that closes in the inner peripheral surface 3 of the entire bearing 1. When the bearing 1 is used, the lubricating oil is impregnated. However, the lubricating oil supplied by infiltrating the closed concave portion 4 has no escape area, and therefore dynamic pressure is easily generated, and the rigidity of the bearing is improved. In addition, each bearing body 1
Since the opening recesses 15 and 25 are formed at 0 and 20 and they are united, the degree of freedom of the shape of the closing recess 4 is increased. In particular, in the case of the first, second, and third embodiments, the cross-sectional area of the closed recess 4 gradually decreases as it goes in the direction of rotation of the rotating shaft, and the end side becomes a wedge-shaped gap. The pressure is quickly generated, and a stable shaft supporting action is exhibited, especially at the time of initial startup of the rotating shaft. Also,
Since the closed concave portion 4 of the first embodiment shown in FIG. 2 has a wedge-shaped gap in both circumferential directions, it effectively corresponds to both forward and reverse rotational directions.

Further, in the case of the bearing 1 of the modified example of the first embodiment shown in FIG. 5, since the joints have a high density, the movement from the boundary between the bearing bodies 10, 20 as described above. In addition to suppressing the pressure leakage, the air permeability and the porosity of the inner surface of the closed concave portion 4 are reduced, and a state in which the lubricating oil hardly permeates into the bearing on the higher pressure side is obtained. Will be retained. Further, when the closed concave portion 4 has a trapezoidal shape as in the fourth embodiment, the lubricating oil is on the upper bottom side (left side in FIG. 9).
However, since this portion is shifted toward one bearing body 20, the leakage of the dynamic pressure from the boundary at the joint is reduced, and a high dynamic pressure is obtained. The performance is improved. Further, when the rotating shaft rotates toward the lower bottom, the concentration of the lubricating oil decreases, but the dynamic pressure is generated in a well-balanced manner in the vicinity of the joint. Since the lower bottom side is substantially subjected to the most load, the rotating shaft is supported with high precision by the generated dynamic pressure.

The shape of the opening recesses 15 and 25 in the first and second bearing bodies 10 and 20 and the shape or the pattern of the closing recess 4 formed by combining the opening recesses 15 and 25 are arbitrary. This is shown in the development views of FIG. 10 and FIG. In the case of FIG. 10A, the opening concave portions 15 and 25 are triangular or trapezoidal, and FIG. 10B is a thin triangular shape.
0 (c) is an irregular shape, and FIG. 11 is a short spiral shape. Also,
The sectional shapes of the opening concave portions 15 and 25 are also arbitrary, and examples thereof are shown in FIGS. In FIG. 12, an arrow A indicates an example of the rotation direction of the rotation shaft. FIG. 13 further shows some of the shape patterns of the opening recesses 15 and 25. In this case, the opening recesses 15 and 25 are connected to the bearing bodies 10 and 2 respectively.
Also, an opening is provided on the end surface of the exposed side of No. 0. In this manner, by opening the opening concave portions 15 and 25 also on the exposed side end surface,
Lubricating oil can be supplied to the closed recess 4 from the outside, and a stable dynamic pressure can be obtained even with a small amount of lubricating oil. In the first to fourth embodiments, the assembling pattern of the first and second bearing bodies 10 and 20 according to the shape of the joint portion is arbitrary, and FIG. FIG. 14B shows an example in which the entire surface is brought into close contact with the first and second bearing bodies 1.
FIG. 14C shows an example in which a ring-shaped chamber 5 for storing lubricating oil is provided between radial boundaries of 0 and 20. FIG. 14C shows a large-diameter portion 16 formed in a bearing hole 13 of the first bearing body 10. Second in
This is an example in which the bearing body 20 of FIG.

(5) Fifth Embodiment Next, a fifth embodiment according to the present invention will be described with reference to FIGS. In a bearing 1 according to a fifth embodiment shown in FIG. 15, ring-shaped first and second bearing bodies 10 and 20 having bearing holes 13 and 23 are joined to each other, and a ring-shaped third bearing body. Reference numeral 30 denotes a joint that extends across the boundary on the outer peripheral surfaces of the first and second bearing bodies 10 and 20. In the inner peripheral surfaces 14 and 24 of the first and second bearing bodies 10 and 20, a plurality of isosceles triangular (only one is shown in the figure) opening recesses 15 whose bases are open to the joining surfaces 11 and 21 are shown. , 25 are formed in the circumferential direction with good balance. As shown in FIG. 16, the cross section of the opening concave portions 15 and 25 along the radial direction is deepest at the center in the circumferential direction.
It gradually becomes shallower toward the both ends in the circumferential direction, and is formed in a curved shape that smoothly continues to the inner peripheral surfaces 14 and 24. In addition, concave steps 17 and 27 are formed along the circumferential direction at the edges of the outer peripheral surfaces of the first and second bearing bodies 10 and 20 on the joint surfaces 11 and 21 side, respectively. Then, the first and second bearing bodies 10 and 20 are joined to form the opening recess 1.
5 and 25 are combined, and both concave steps 17 and 27 are combined.
The third bearing body 30 is joined to the groove 6 formed by the step (1), and the bearing 1 is assembled. On the inner peripheral surface 3 of the entire bearing 1, a plurality of closed concave portions 4 whose peripheral edges are closed in the inner peripheral surface 3 are formed in the inner peripheral surface 3 in a well-balanced manner by combining the open concave portions 15 and 25. These closed recesses 4 have a rhombic shape whose axial length is reduced toward both ends in the circumferential direction, and have a shape that can cope with both forward and reverse rotation directions.

In the bearing 1 of the fifth embodiment,
The closed recesses 4 are easily formed by combining the open recesses 15 and 25, and the lubricating oil in the closed recess 4 has no escape area, so that dynamic pressure is easily generated. Furthermore, since the closed concave portion 4 has wedge-shaped gaps at both ends in the circumferential direction, a high dynamic pressure can be obtained, and a high dynamic pressure can be obtained even if the rotating shaft rotates in either the forward or reverse direction.

(6) Sixth Embodiment Next, a sixth embodiment according to the present invention will be described with reference to FIG. In the bearing 1 of the sixth embodiment, the first and second bearing bodies 20 and 30 are joined to both sides of the first bearing body 10 at the center in the axial direction. The joint surface 11 of the first bearing body 10 and the joint surfaces 21 and 31 of the second and third bearing bodies 20 and 30 that are in close contact with the joint surface 11 have:
Step portions 12, 22, 32 to be fitted to each other are formed. Inner peripheral surface 14 of bearing hole 13 of first bearing body 10
In this example, a plurality of short spiral-shaped opening recesses 15 that open to the joint surfaces 11 on both sides are formed with good balance in the circumferential direction. These opening recesses 15 extend obliquely in the direction of rotation of the rotation shaft indicated by arrow A in the figure. On the other hand, the inner peripheral surface 2 of the bearing holes 23, 33 of the second and third bearing bodies 20, 30
3 and 34 have opening recesses 2 that open to the joint surfaces 21 and 31.
5, 35 are formed respectively. These opening recesses 2
Reference numerals 5 and 35 denote a combination of peripheral grooves (escape recesses) 25a and 35a opened on the joint surfaces 21 and 31 and short spiral grooves 25b and 35b branched from the peripheral grooves 25a and 35a. 25b and 35b extend obliquely in the rotation direction of the rotation shaft. The depth of each circumferential groove 25a, 35a is deeper than the spiral grooves 25b, 35b.

The bearing 1 has a stepped portion 12 on both sides of a first bearing body 10 and a stepped portion 2 of second and third bearing bodies 20 and 30.
It is obtained by fitting and joining the members 2 and 32 respectively. In this bearing 1, the opening recess 15 of the first bearing body 20 and the circumferential grooves 25 a of the second and third bearing bodies 20 and 30,
35a is united with the inner peripheral surface 3 of the bearing 1,
Opening recess 15 and spiral groove 2 from both sides of circumferential grooves 25a, 35a
A closed recess 4 is formed in which 5b and 35b branch obliquely in the rotation direction of the rotation shaft. This closed recess 4 is
The peripheral edge is closed in the inner peripheral surface 3 of the entire bearing 1.

Next, similarly to the sixth embodiment, the first to third bearing bodies 10, 20, 30 divided into three in the axial direction are joined in the axial direction to form the seventh to seventh bearings. A ninth embodiment will be described. (7) Seventh Embodiment FIG. 22 shows a state where the bearing 1 of the seventh embodiment is divided. In this case, the inner peripheral surface 14 of the first bearing body 10 is formed with a plurality of two types of opening recesses, that is, first and second opening recesses 15A and 15B that open to the joint surfaces 11 on both sides. The first opening recess 15A has a substantially quarter-arc shape, and the arc portion is oriented in the direction of rotation of the rotation shaft indicated by arrow A. The second opening recess 15B has a short spiral shape extending along the arc of the first opening recess 15A.
These first and second opening recesses 15A and 15B are arranged alternately and in a well-balanced manner along the circumferential direction. On the other hand, the inner peripheral surfaces 24, 34 of the second and third bearing bodies 20, 30
In the state of being joined to the first bearing body 10, the first opening recesses 25A, 35A and the second opening recess 25B, which are symmetrical with the respective opening recesses 15A, 15B of the first bearing body 10, are provided. , 35B are formed. Then, the first and second bearing members 20 and 30 are joined together with the first bearing member 10 interposed therebetween, so that the first opening recess 1 of the first bearing member 10 is formed.
5A and the first opening recesses 25A and 35A of the second and third bearing bodies 20 and 30 are combined, and the second opening recess 15B of the first bearing body 10 and the second and third bearing bodies 20 and 30 are combined. 30 second
The opening concave portions 25B and 35B are combined to form a semicircular and V-shaped closed concave portion that is closed in the inner peripheral surface 3 of the bearing 1.

Each of the second opening recesses 15B, 25B,
35B may be formed in the opposite direction as shown by the broken line in FIG. 22, or both may be compatible. In that case, 1
Since it cannot be formed by the die cutting in the green compaction of one time,
The second opening recesses 15B, 25B, 35B on the same side as the first opening recesses 15A, 25A, 35A in the same die-cutting direction are formed at the same time.
B, 25B, and 35B are formed in two steps, for example, or the reverse method is adopted.

FIG. 23 shows a modification of the seventh embodiment. In this embodiment, the first bearing 10
The inner diameter of the bearing hole 13 is composed of a large diameter portion 13a and a small diameter portion 13b which are coaxial with each other. The bearing hole 23 of the second bearing body 20 is formed in the large diameter portion 13a, and the inner diameter of the bearing hole 33 of the third bearing body 30 is formed in the size corresponding to the small diameter portion 13b. In this case, the rotation axis is
Substantially, the small-diameter portion 13b of the first bearing body 10 and the third
The bearing body 30 is supported by the inner peripheral surface 34 of the bearing hole 33.

(8) Eighth Embodiment In the bearing 1 of the eighth embodiment shown in FIG. 17, the first and second bearing bodies 10 and 20 joined in the axial direction are the third bearing body.
Are housed and joined inside the bearing body 30. Third
The inner peripheral surface 34 of the bearing body 30 is formed with a large-diameter portion 36 that opens to one end face, and the first and second bearing bodies 10 and 20 are housed in the large-diameter portion 36. I have. Although the bearing holes 13, 23, and 33 of the bearing bodies 10, 20, and 30 have the same diameter, the inner peripheral surface 14 of the bearing hole 13 of the first bearing body 10 has a shape that is closer to one side in the circumferential direction. Open recesses 15 which become gradually shallower and open to the joint surfaces 11 on both sides are formed. The opening concave portion 15 becomes the closed concave portion 4 whose peripheral edge is closed in the inner peripheral surface 14 of the entire bearing 1 by joining the second and third bearing bodies 20 and 30.
In addition, a through-hole 7 is provided in the inner peripheral surface 34 of the third bearing body 30 so as to communicate from the end face to the deeper side of the closed recess 4, and lubricating oil can be supplied from the through hole 7 to the closed recess 4. It may be.

(9) Ninth Embodiment In the bearing 1 of the ninth embodiment shown in FIG.
The second and third bearing bodies 20, 3 with the bearing body 10 interposed therebetween.
Reference numeral 0 indicates that the steps 12, 22, and 32 are fitted and joined. On the inner peripheral surface 14 of the first bearing body 10, there is formed an opening recess 15 which opens to the same joint surface 11 as in the sixth embodiment. In addition to this, the second and third bearing bodies are provided. 20,
Opening recesses 25 and 35 that open to the joint surfaces 21 and 22 are respectively formed on the inner peripheral surface of 30. The opening concave portions 25 and 35 are formed in an elongated triangular shape whose axial length gradually decreases toward one side in the circumferential direction. When the bearing bodies 10, 20, 30 are joined and assembled into the bearing 1, the opening recess 15 and the opening recess 2 are formed.
5 and 35 are combined to form a closed recess 4 whose peripheral edge is closed in the inner peripheral surface 3 of the entire bearing 1.

In the bearings 1 of the sixth, seventh and ninth embodiments, the opening recess 15 (15) of the first bearing body 10 is provided.
A, 15B) and the opening recesses 25, 35 (25A, 25B, 35A, 35B) of the second and third bearing bodies 20, 30 are united, whereby the closed recess 4 is easily formed.
Further, in the bearing 1 according to the eighth embodiment, the opening concave portion 15 of the first bearing body 10 is provided with the second and third bearing bodies 20 and 3.
0 is closed by joining, and the closed recess 4 is easily formed.
Is formed. In the bearing 1 in which these closed concave portions 4 are formed, there is no escape for the supplied lubricating oil.
Dynamic pressure is easily generated. In addition, by making the density of the first bearing body 10 at the center higher than that of the second and third bearing bodies 20 and 30 on both sides, the second and third bearing bodies on both sides are increased in accordance with the difference in pore diameter in the bearing. The lubricating oil circulates from the bearing members 20 and 30 to the first bearing member 10 to improve lubricity.
Further, since the pore diameter of the portion where the dynamic pressure is generated is small, the leakage of the dynamic pressure is suppressed.

In the sixth embodiment, the circumferential grooves 25a,
Since 35a is deeper than the spiral grooves 25b and 35b and the supply amount of lubricating oil increases, friction loss is reduced and coaxial accuracy is improved, and lubricating oil stored at the bottom of the circumferential grooves 25a and 35a is reduced. The dynamic pressure is more easily generated by being supplied to the closing recess 4. In addition, as described above, the circumferential grooves 25a, 35
a instead of deepening a to form the escape recess,
If a deep relief recess is formed in a part of the b and 35b, it is possible to contribute to the generation of the dynamic pressure and to obtain a high dynamic pressure. In addition, if the relief recess is formed along the axial direction, it is effective in generating dynamic pressure.

In the case of the seventh embodiment, the closed recess 4
Since the lubricating oil concentrates on the end of the rotating shaft on the rotation direction side, a high dynamic pressure can be obtained. In the case of the eighth embodiment, if the direction of rotation of the rotating shaft is the direction of arrow A, a high dynamic pressure can be obtained for the same reason. Here, since the generation of the dynamic pressure becomes maximum at two joints in the bearing, the rotating shaft is supported with high accuracy. Further, in the case of the modification of the seventh embodiment, since the friction loss of the upper and lower bearing inner peripheral surfaces in the figure is different, it is adjusted according to the use condition (such as lowering the surface pressure by using a large diameter when the upper surface pressure is high). By arbitrarily setting the inner diameter, the degree of freedom in designing the bearing is increased.

In the sixth to ninth embodiments, the opening recesses 15, 25, 35 and the opening recesses 15, 2
The shape of the closed concave portion 4 or the pattern of the united portions 5 and 35 formed by the uniting are arbitrary, and an example thereof is shown in a developed view of FIG. Further, the cross-sectional shapes of the opening concave portions 15, 25, 35 are also
It is optional as in FIG.

While the first to ninth embodiments according to the present invention have been described above, the present invention includes those in which the following features are added to these embodiments. The closing recess is formed when the bearing body is recompressed. This corresponds to, for example, the cores 40a, 40b, 4 as shown in FIG.
0c is inserted into the bearing hole, the bearing body is pressed in the axial direction, and the inner peripheral surface is pressed against the core to form a closed recess corresponding to the core. According to this method, the portion processed by the convex portion of the core, that is, the closed concave portion has a high degree of processing, and therefore has a higher density and a lower porosity than the other portions, and the generated dynamic pressure leakage is suppressed. In addition, if the machining allowance for the closed concave portion is increased, the density of the inner surface of the closed concave portion is further increased, and the effect of suppressing the dynamic pressure leak is greatly improved.
Further, it is not necessary to form the opening concave portion when molding the green compact, and the manufacturing process is simplified.

In each of the above embodiments, a sintered alloy is used as the porous material. However, the present invention is not limited to this, and a single material such as resin, ceramics, cermet, or two or more of these may be used. The combined composite material may be used as a porous material. Also, the contained lubricant,
A fluid such as water or air is used as appropriate in addition to the lubricating oil.

[0037]

As described above, in the porous composite bearing of the present invention, a closed recess that closes in the inner peripheral surface of the bearing can be easily formed, and dynamic pressure is generated in the closed recess. The bearing performance is improved by suppressing the leakage of the generated dynamic pressure. Further, according to the method for manufacturing a porous composite bearing of the present invention, a bearing having a closed concave portion closed in the inner peripheral surface can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which a bearing according to a first embodiment of the present invention is vertically split.

FIG. 2 is a sectional view of an opening concave portion of the bearing according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view showing another form of the opening concave portion of the bearing according to the first embodiment of the present invention.

FIG. 4 is a perspective view of a modified example of the bearing according to the first embodiment of the present invention, showing a state in which first and second bearing bodies constituting the bearing are vertically divided.

FIG. 5 is a perspective view of a state in which a bearing according to a modification according to the first embodiment of the present invention is vertically split.

FIG. 6 is a perspective view of a state in which a bearing according to a second embodiment of the present invention is vertically split.

FIG. 7 is a sectional view of an opening concave portion of a bearing according to a second embodiment of the present invention.

FIG. 8 is a perspective view of a state in which a bearing according to a third embodiment of the present invention is vertically split.

FIG. 9 is a perspective view showing a state in which a bearing according to a fourth embodiment of the present invention is vertically split.

FIG. 10 is a development view showing various shape patterns of an opening concave portion of the bearing according to the first to fourth embodiments of the present invention.

FIG. 11 is a developed view showing another shape pattern of the opening concave portion of the bearing according to the first to fourth embodiments of the present invention.

FIG. 12 is a cross-sectional view showing a pattern of a cross-sectional shape of an opening concave portion of the bearing according to the first to fourth embodiments of the present invention.

FIG. 13 is a developed view showing another shape pattern of the opening concave portion of the bearing according to the first to fourth embodiments of the present invention.

FIG. 14 is a sectional view showing an assembly pattern of the bearing according to the first to fourth embodiments of the present invention.

FIG. 15 is a perspective view showing a state in which a bearing according to a fifth embodiment of the present invention is vertically split.

FIG. 16 is a cross-sectional view of an opening concave portion of a bearing according to a fifth embodiment of the present invention.

FIG. 17 is a perspective view showing a state in which a bearing according to an eighth embodiment of the present invention is vertically split.

FIG. 18 is a perspective view showing a state in which a bearing according to a ninth embodiment of the present invention is vertically split.

FIG. 19 is a developed view showing a shape pattern of an opening concave portion of the bearing according to the sixth to ninth embodiments of the present invention.

FIG. 20 is a perspective view showing a form of a core used when the closed recess of the bearing according to the present invention is formed by recompression.

FIG. 21 is a plan view showing a state in which a bearing according to a sixth embodiment of the present invention is vertically split.

FIG. 22 is a plan view showing a state in which a bearing according to a seventh embodiment of the present invention is vertically split.

FIG. 23 is a plan view showing a modification of the bearing according to the seventh embodiment of the present invention, in which the bearing is split vertically.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bearing, 2 ... Bearing hole of bearing, 3 ... Inner peripheral surface of bearing, 4 ... Closed recessed part, 10 ... 1st bearing body, 11, 21, 31 ... Joint surface, 13, 23, 33 ... Bearing body Bearing holes, 14, 24, 34 ... inner peripheral surface of bearing body, 15, 15A, 15B, 25, 25A, 25B, 35,
35A, 35B: Open recess, 20: Second bearing body, 25a, 35a: circumferential groove (relieving recess), 30: Third bearing body.

Claims (11)

[Claims] At least two or more porous bearing bodies containing a fluid lubricant are combined by being joined in an axial direction so as to be continuous with each other, and at least one of the bearing bodies joined to each other is provided. By forming an opening concave portion that opens to at least one end surface side joining surface on one bearing inner peripheral surface, a closed concave portion whose peripheral edge is closed in the rotational direction is formed in the inner peripheral surface of the entire combined bearing. A porous composite bearing characterized by being made. 2. An opening recessed to the joint surface is formed on each of the inner peripheral surfaces of both of the bearing bodies joined to each other, and the openings of the opening recesses abut each other to form the closed recess. The porous composite bearing according to claim 1, wherein: 3. The porous composite bearing according to claim 1, wherein a vertical cross-sectional area of the closed concave portion changes in a direction of rotation of the rotating shaft. 4. The porous composite bearing according to claim 1, wherein said bearings have different air permeability and / or porosity. 5. The perforated hole according to claim 1, wherein a relief recess deeper than the opening recess is formed on the joining surface side of at least one peripheral surface of the bearing body. Quality composite bearing. 6. The porous composite bearing according to claim 1, wherein the inner diameter of the bearing changes in the axial direction. 7. The porous composite bearing according to claim 1, wherein an inner surface of the closed concave portion has a higher density than other portions. 8. An axially projecting convex portion is formed in advance on the joint surface on the side of the opening concave portion, and the bearing body is brought into close contact by pressing the convex portion at the time of the recompression. The porous composite bearing according to claim 1, wherein: 9. The method for producing a porous composite bearing according to claim 1, wherein each of the bearing bodies is formed of a porous material, and then the bearing bodies are connected. The method of manufacturing a porous composite bearing, wherein the joint surfaces are combined together and recompressed, and at the time of the recompression, the respective bearing bodies are pressed in the axial direction so as to adhere to each other and the closed concave portion is formed. . 10. An axially projecting convex portion is formed in advance on the joint surface on the side of the opening concave portion, and the bearing body is brought into close contact by pressing the convex portion during the recompression. The method for manufacturing a porous composite bearing according to claim 9. 11. The method for manufacturing a porous composite bearing according to claim 9, wherein a machining allowance for said closed concave portion is increased to increase the density of the inner surface of said closed concave portion.