WO2016152474A1 - Bearing member, fluid dynamic pressure bearing device equipped with same, and method of manufacturing bearing member - Google Patents

Abstract

Provided is a bearing member 8 that comprises: a plurality of sintered bodies 81, 82 having bearing surfaces A1, A2 on inner peripheral surfaces thereof; and an intermediate sleeve 83 that is arranged between the plurality of sintered bodies 81, 82 in an axial direction. The plurality of sintered bodies 81, 82 are sized in a state where the plurality of sintered bodies 81, 82 and the intermediate sleeve 83 are joined together. The axial-direction deformation under load of the intermediate sleeve 83 is smaller than the axial-direction deformation under load of each of the sintered bodies 81, 82.

Description

Bearing member, fluid dynamic pressure bearing device including the same, and method for manufacturing bearing member

The present invention relates to a bearing member used in a fluid dynamic pressure bearing device and a method for manufacturing the same, and particularly to a bearing member having a plurality of sintered bodies.

Sintered metal bearing members (hereinafter, sintered bearings) are usually manufactured through compacting (forming), sintering, and re-pressure (sizing). In particular, in the re-pressing step, with the core rod inserted into the inner periphery of the sintered body, the core rod is inserted into the inner periphery of the die, and further, the sintered body is pressed from both sides in the axial direction. Molding to the dimensional accuracy of

In order to increase the bearing rigidity of such sintered bearings, especially the bearing rigidity against moment load, it is effective to increase the axial interval (bearing span) of the multiple bearing surfaces formed on the inner peripheral surface of the sintered bearing. It is. In order to widen the bearing span, it is necessary to lengthen the sintered bearing in the axial direction. However, if sizing is performed on a sintered bearing that is long in the axial direction, the pressing force cannot be transmitted to the central portion in the axial direction, and there is a possibility that molding cannot be performed with a predetermined dimensional accuracy.

For example, if a plurality of sintered bearings having relatively small axial dimensions are used side by side in the axial direction, each sintered bearing can be accurately molded. However, in this case, when assembling a plurality of sintered bearings, it is necessary to center the bearing surface of each sintered bearing. Such a centering operation is not easy, and it is very difficult to accurately arrange the relative positions (for example, cylindricity) of a plurality of bearing surfaces.

For example, FIG. 3 of Patent Document 1 below shows a bearing member (composite porous bearing) formed by combining a plurality of sintered bodies. Specifically, after each of the plurality of sintered bodies is formed, they are put in a sizing mold in a combined state, and pressed from above and below with a core rod passed through the inner periphery. As a result, a plurality of sintered bodies are firmly joined, and at the same time, the bearing surface of each sintered body is finished and centered. In this way, by fixing the plurality of sintered bodies by sizing and simultaneously performing finishing and centering on the plurality of bearing surfaces, the relative direction of the plurality of bearing surfaces in the radial direction can be achieved without increasing the number of man-hours. The position can be set with high accuracy.

Japanese Patent No. 3475215

However, since the sintered metal is a porous body, deformation is likely to occur due to pressurization during sizing. Therefore, when pressing in the axial direction in a state where a plurality of sintered bodies are combined, each sintered body is compressed in the axial direction, so the amount of deformation in the axial direction of the entire bearing member increases, resulting in the following problems May occur.
(1) The total axial length of the bearing members and the axial intervals (bearing spans) of a plurality of bearing surfaces vary from product to product.
(2) A sufficient pressing force is not applied to each sintered body, and the dimensional accuracy of each sintered body, particularly the inner diameter of the bearing surface, varies from product to product.
(3) The pressing force applied to each sintered body becomes non-uniform, and the inner diameter dimensions of a plurality of bearing surfaces differ in each bearing member.

In particular, when the dynamic pressure grooves are formed on the bearing surface of each sintered body by sizing, if the amount of deformation of each sintered body is large, the forming accuracy of the dynamic pressure grooves may be insufficient, or the state of the dynamic pressure grooves may be There is a risk that it varies from product to product.

In view of the above circumstances, the first problem to be solved by the present invention is to increase the dimensional accuracy of a bearing member having a plurality of sintered bodies.

As is well known, a fluid dynamic pressure bearing device has features such as high-speed rotation, high rotation accuracy, and low noise. Therefore, a spindle motor incorporated in a disk drive device such as an HDD and a fan motor incorporated in an electronic device. Alternatively, it is suitably used as a bearing device for a motor such as a polygon scanner motor incorporated in a laser beam printer.

A fluid dynamic pressure bearing device includes a bearing member having a cylindrical radial bearing surface on an inner periphery, a shaft member inserted into the inner peripheral surface of the bearing member, a radial bearing surface of the bearing member, and an outer peripheral surface of the shaft member. And a radial bearing portion that supports the shaft member in a radial direction so as to be relatively rotatable with a lubricating film (for example, an oil film) of fluid generated in a radial bearing gap therebetween. As the bearing member, a radial bearing surface is provided at two locations spaced apart in the axial direction on the inner peripheral surface, and a so-called cylindrical surface (medium escape portion) having a larger diameter than the radial bearing surface is provided between both radial bearing surfaces. In some cases, a middle relief structure is employed.

The bearing member having a center relief structure may be configured by a single cylindrical body or may be configured by combining and integrating a plurality of cylindrical bodies arranged in an axial direction. In any case, as the cylindrical body having a radial bearing surface, a cylindrical body made of a sintered metal excellent in workability (mass productivity) and oil film forming ability in the radial bearing gap is used.

For example, FIG. 1 of Patent Document 1 described above discloses a bearing member in which a middle escape portion is formed by joining two cylindrical bodies arranged in an axial direction. Specifically, with reference to FIG. 15 of the present application, the bearing member 200 is obtained by integrating a first cylindrical body 210 and a second cylindrical body 220 made of sintered metal by a coupling portion 204. A first radial bearing surface 201 is provided on the inner periphery of the first cylindrical body 210, and a second radial bearing surface 202 and a diameter larger than those of the radial bearing surfaces 201 and 202 are provided on the inner periphery of the second cylindrical body 220. And a cylindrical surface (medium escape portion) 203 are provided.

The bearing member 200 is finished into a finished product shape using a sizing mold 230 shown in FIGS. 16A to 16C. Specifically, first, as shown in FIG. 16A, a cylindrical small diameter provided at the upper end of the second cylindrical body 220 (strictly, the cylindrical material finished to the second cylindrical body 220 shown in FIG. 15 by sizing). The outer peripheral surface 221 and the cylindrical large-diameter inner peripheral surface 211 provided at the lower end of the first cylindrical body 210 (strictly, the cylindrical material finished to the first cylindrical body 210 shown in FIG. 15 by sizing) are fitted. To construct an assembly. With the core rod 231 inserted into the inner periphery of the assembly, as shown in FIG. 16B, the assembly, the core rod 231 and the upper punch 233 are integrally lowered to press-fit the assembly into the inner periphery of the die 232. Then, as shown in FIG. 16C, the assembly, the core rod 231, and the upper punch 233 are further lowered, and the assembly is pressed in the axial direction by the upper punch 233 and the lower punch 234. As described above, the inner peripheral surfaces of the cylindrical bodies 210 and 220 are pressed against the core rod 231 to form the radial bearing surfaces 201 and 202, and between the cylindrical bodies 210 and 220 (particularly between the radial bearing surfaces 201 and 202). Coaxial out at is performed. At the same time, both the cylindrical bodies 210 and 220 are pressed from the inner diameter side and the outer diameter side by the core rod 231 and the die 232, and the large diameter inner peripheral surface 211 of the first cylindrical body 210 and the small diameter outer periphery of the second cylindrical body 220. The coupling | bond part 204 which couple | bonds both the cylindrical bodies 210 and 220 is formed in close contact with the surface 221.

As described above, according to the technical means disclosed in Patent Document 1, even when a plurality (two) of cylindrical bodies are coupled, the coaxiality between two radial bearing surfaces spaced apart in the axial direction can be increased. It is considered that high accuracy can be ensured. However, since each cylindrical body constituting the bearing member 200 is a mass-produced part, it is not always formed in the same shape and size. Actually, the shape and size of each part of the first cylindrical body 210 and the second cylindrical body 220 vary from product to product. Therefore, when the bearing member 200 is obtained, for example, as shown in FIG. 17A, a first cylindrical body 210 having a different thickness in each circumferential direction due to uneven thickness may be used. For ease of understanding, the degree of uneven thickness is exaggerated in the illustrated example.

At this time, as described with reference to FIGS. 16A to 16C, if both cylinders 210 and 220 are sized in a state in which both cylinders 210 and 220 are fitted in advance (concave fitting), the second cylinder The presence of the body 220 restricts the movement of the first cylindrical body 210 inward in the radial direction. For this reason, the shaping | molding scheduled area | region of the radial bearing surface 201 among the internal peripheral surfaces of the 1st cylindrical body 210 cannot be pressed appropriately on the outer peripheral surface of the core rod 231, but it is predetermined on the internal peripheral surface of the 1st cylindrical body 210. There is a possibility that the radial bearing surface 201 having the shape and accuracy cannot be formed. In this case, the required coaxiality between the radial bearing surfaces 201 and 202 cannot be ensured (see FIG. 17B).

In view of the above circumstances, the second problem to be solved by the present invention is a combination of a plurality of cylindrical bodies arranged in an axial direction, and a pair of radial bearing surfaces separated in the axial direction on the inner periphery. It is possible to properly secure the shape and dimensional accuracy of each radial bearing surface and the coaxiality between both radial bearing surfaces while appropriately connecting the cylindrical bodies in the bearing member for the fluid dynamic bearing device having Thus, it is possible to realize a fluid dynamic pressure bearing device having excellent bearing performance in the radial direction.

In order to solve the first problem, the first invention of the present application includes a plurality of sintered bodies having bearing surfaces on an inner peripheral surface, and an intermediate sleeve disposed between the axial directions of the plurality of sintered bodies. A bearing member provided integrally, wherein the amount of load deformation in the axial direction of the intermediate sleeve is smaller than the amount of load deformation in the axial direction of each sintered body is provided.

In order to solve the above problems, the first invention of the present application forms a plurality of cylindrical sintered bodies and an intermediate sleeve having a smaller amount of axial load deformation than each sintered body. And inserting the assembly into the inner periphery of the die in a state where the core rod is inserted into the inner periphery of the assembly composed of the plurality of sintered bodies and the intermediate sleeve disposed between the plurality of sintered bodies. By pressing the assembly from both sides in the axial direction, the inner peripheral surfaces of the plurality of sintered bodies are pressed against the outer peripheral surface of the core rod, and a bearing surface is formed on the inner peripheral surfaces of the plurality of sintered bodies. A method of manufacturing a bearing member having a process is provided.

The “load deformation amount” means a deformation amount including elastic deformation and plastic deformation when a predetermined load (for example, a load during sizing) is applied to each member.

As described above, the intermediate sleeve disposed between the axial directions of the plurality of sintered bodies has a smaller axial load deformation amount than the sintered body, thereby reducing the axial deformation amount of the intermediate sleeve due to compression during sizing. Can be suppressed. Thereby, since the deformation amount of the entire bearing member is suppressed, variations in the axial length of the bearing member and axial intervals (bearing spans) of a plurality of bearing surfaces for each product can be suppressed. In addition, since the intermediate sleeve becomes difficult to be compressed, a sufficient pressing force can be applied to each sintered body, so that the dimensional accuracy of each sintered body, particularly the accuracy of the inner diameter of the bearing surface can be increased. Furthermore, by suppressing the deformation amount of the intermediate sleeve, it is possible to apply a pressing force uniformly to each sintered body, and thus it is possible to suppress differences in the inner diameter dimensions of the plurality of bearing surfaces in each bearing member.

For example, if the intermediate sleeve is formed of a melted material, in particular, a melted material made of the same metal as the plurality of sintered bodies (the main component is the same metal), the amount of load deformation can be made smaller than each sintered body. It becomes possible.

Incidentally, since the load deformation amount is a deformation amount including plastic deformation, it is a parameter different from the elastic modulus representing the ratio between the load and the deformation amount in the elastic deformation. However, when the elastic modulus of one member is greater than that of the other member, the deformation amount of both rarely reverses in the plastic region. Therefore, in practice, one member having a large elastic modulus is the other member. It can be considered that the load deformation amount is smaller than that. Therefore, if the intermediate sleeve is formed of a material having a larger elastic modulus than each sintered body, the load deformation amount in the axial direction of the intermediate sleeve is usually smaller than that of each sintered body.

A radial dynamic pressure generating portion such as a dynamic pressure groove may be formed on the bearing surfaces of the plurality of sintered bodies. For example, a radial dynamic pressure generating portion can be formed on the bearing surfaces of a plurality of sintered bodies by providing a forming die on the outer peripheral surface of the core rod and pressing the inner peripheral surfaces of the plurality of sintered bodies against the forming die. . In this case, since the load deformation amount of the intermediate sleeve is small as described above, the inner peripheral surfaces of the plurality of sintered bodies are pressed against the forming die on the outer peripheral surface of the core rod with sufficient force. Molding accuracy is increased.

In order to solve the second problem, in the second invention of the present application, a first cylindrical body made of sintered metal disposed at one end in the axial direction and a second body made of sintered metal disposed at the other end in the axial direction. A step of arranging a plurality of cylindrical bodies including a cylindrical body in an axial direction, and inserting the plurality of cylindrical bodies into the inner periphery of the die with a core rod inserted into the inner periphery of the plurality of cylindrical bodies, By pressing the plurality of cylindrical bodies from both sides in the axial direction, the inner peripheral surface of the first cylindrical body and the inner peripheral surface of the second cylindrical body are pressed against the outer peripheral surface of the core rod so as to be separated in the axial direction. A method of manufacturing a bearing member is provided that includes forming the pair of radial bearing surfaces and providing a middle relief portion having a larger diameter than the radial bearing surfaces between the axial directions of the radial bearing surfaces. In this manufacturing method, a concave portion is provided in advance on one end surface of two cylindrical bodies adjacent in the axial direction, and a flat surface is provided on the other end surface of the two cylindrical bodies adjacent in the axial direction. By pressing the plurality of cylindrical bodies from both sides in the axial direction, convex portions that are in close contact with the concave portions are formed on the flat surface.

The “radial bearing surface” as used in the present invention means a surface that forms a radial bearing gap with the outer peripheral surface of the shaft to be supported, and a dynamic pressure generating portion such as a dynamic pressure groove is formed on this surface. It doesn't matter whether it is done or not.

As described above, in the present invention, by pressing a plurality of cylindrical bodies from both sides in the axial direction, sizing is performed, and at the same time, a recess provided in one of the two adjacent cylindrical bodies is made to be adjacent to two adjacent cylindrical bodies. Press against a flat surface provided on the other of the cylinders. As a result, the flat surface is plastically deformed, and a convex portion that is in close contact with the concave portion is formed on the flat surface. In this case, the concave portion and the flat surface are not engaged in the radial direction at the start of compression. For this reason, until the convex part is formed on the flat surface to some extent, the radial movement of one of the two cylindrical bodies adjacent in the axial direction is not restricted by the presence of the other. Therefore, the inner peripheral surfaces of the first cylindrical body and the second cylindrical body can be pressed against the outer peripheral surface of the core rod with sufficient force and deformed following the outer peripheral surface of the core rod. Therefore, it is possible to obtain a bearing member in which the cylindrical bodies adjacent to each other in the axial direction are firmly coupled with each other in a state in which both radial bearing surfaces are formed with a predetermined accuracy and the coaxial alignment between both the radial bearing surfaces is appropriately performed. Can do.

According to the above manufacturing method, the first cylindrical body made of sintered metal disposed at one end in the axial direction and the second cylindrical body made of sintered metal disposed at the other end in the axial direction are arranged continuously in the axial direction. A plurality of cylindrical bodies, a radial bearing surface provided on each of the inner peripheral surface of the first cylindrical body and the inner peripheral surface of the second cylindrical body, and an axial direction between both radial bearing surfaces. It is possible to obtain a bearing member having a middle escape portion having a diameter larger than that of the bearing surface. The bearing member is provided on a concave portion provided on one end surface of two cylindrical bodies adjacent in the axial direction and on the other end surface of the two cylindrical bodies adjacent in the axial direction. It has a convex part that is formed by plastic deformation by pressure welding and that is in close contact with the concave part.

As a specific example of a bearing member to which the present invention can be applied, the concave portion is provided on the end surface of the first cylindrical body, and the convex portion formed by plastic deformation by pressure contact of the concave portion is provided on the end surface of the second cylindrical body. There may be provided an inner peripheral portion of the first cylindrical body or an inner peripheral surface of the second cylindrical body provided with the intermediate relief portion. In this case, if the yield point of the first cylindrical body is set larger than the yield point of the second cylindrical body, the concave portion of the first cylindrical body is deformed with sizing, and the first and second cylindrical bodies are deformed. It is possible to prevent a situation in which the binding force with the power is reduced.

As another example of a bearing member to which the present invention can be applied, the plurality of cylindrical bodies have a third cylindrical body arranged between the first cylindrical body and the second cylindrical body in the axial direction. Can be mentioned. In this case, for example, the concave portions are provided on both end surfaces of the third cylindrical body in the axial direction, and the convex portions formed by plastic deformation by pressure contact of the concave portions are formed on the end surfaces of the first cylindrical body and the second cylindrical body. And a middle escape portion can be provided on the inner peripheral surface of the third cylindrical body. At this time, if the yield point of the third cylinder is made larger than the yield points of the first and second cylinders, the recesses of the third cylinder are deformed with sizing, and the first cylinder and the second cylinder are deformed. A situation in which the coupling force between the two cylinders and the third cylinder is reduced can be prevented. Such a third cylindrical body is obtained, for example, by forming with a melted material such as stainless steel or brass.

In the above configuration, a dynamic pressure generating portion such as a dynamic pressure groove can be provided on both radial bearing surfaces. This dynamic pressure generating portion can be molded simultaneously with sizing of a plurality of cylindrical bodies. A bearing member having a dynamic pressure generating portion on a radial bearing surface is generally a bearing member having no dynamic pressure generating portion on the radial bearing surface (a bearing having a radial bearing surface formed on a smooth cylindrical surface). Compared to the member), it is used in a region where the gap width of the radial bearing gap formed between the outer peripheral surface of the shaft to be supported is small and the coaxiality required between the two radial bearing surfaces is relatively Becomes smaller. In this respect, in the bearing member according to the present invention, the coaxiality between the two radial bearing surfaces can be appropriately ensured as described above. Therefore, the present invention can achieve further effects in the bearing member in which the dynamic pressure generating portion is provided on the radial bearing surface.

Further, in the bearing member according to the present invention, a thrust bearing surface that forms a thrust bearing gap between the end surface of the shaft to be supported is provided on at least one of the end surface of the first cylinder and the end surface of the second cylinder. You can also. This thrust bearing surface can also be formed simultaneously with the sizing of the plurality of cylindrical bodies.

As described above, in the bearing member according to the present invention, the cylindrical bodies adjacent in the axial direction are appropriately coupled to each other, and the degree of coaxiality between the radial bearing surfaces provided at two positions separated in the axial direction. Is adequately secured. Therefore, the bearing member, the shaft member inserted in the inner periphery of the bearing member, the housing in which the bearing member is fixed to the inner periphery, and the radial bearing gap between the radial bearing surface of the bearing member and the outer peripheral surface of the shaft member The fluid dynamic pressure bearing device including the radial bearing portion that supports the shaft member in a non-contact manner with the fluid pressure generated in the above-described manner has low torque and excellent bearing rigidity (moment rigidity). Further, due to the structure of the bearing member according to the present invention, even if the shaft to be supported is long in the axial direction, it can be accurately supported. Therefore, the fluid dynamic pressure bearing device including the bearing member according to the present invention can be used as a bearing for a relatively large motor (for example, a fan motor for a server).

As described above, according to the first invention of the present application, since the amount of deformation of the intermediate sleeve in the axial direction during sizing is suppressed, the dimensional accuracy of the bearing member formed by combining a plurality of sintered bodies and the intermediate sleeve can be improved. it can.

In addition, as described above, according to the second invention of the present application, in the bearing member composed of a plurality of cylindrical bodies arranged in the axial direction, the shape and dimensions of each radial bearing surface while appropriately connecting the cylindrical bodies. The accuracy and the degree of coaxiality between both radial bearing surfaces can be appropriately ensured.

It is sectional drawing of a fan motor. It is sectional drawing of the fluid dynamic pressure bearing apparatus integrated in the said fan motor. It is sectional drawing of the bearing member which concerns on one Embodiment of this-application 1st invention integrated in the said fluid dynamic pressure bearing apparatus. It is a bottom view of the bearing member. It is a top view of the lid member of the fluid dynamic pressure bearing device. It is a block diagram which shows the manufacture procedure of the said bearing member. It is sectional drawing which shows the state which set the assembly of the some sintered compact and the intermediate sleeve to the sizing metal mold | die. It is sectional drawing which shows the state which inserted the core rod in the inner periphery of the said assembly. It is sectional drawing which shows a mode that sizing is carried out to several sintered compact by press-fitting the said assembly to the inner periphery of die | dye. It is sectional drawing which shows the state which discharged | emitted the assembly (bearing member) after sizing from die | dye. It is sectional drawing which shows the state which pulled out the core rod from the inner periphery of the bearing member. It is sectional drawing of the bearing member which concerns on other embodiment. It is a top view of the bearing member of FIG. FIG. 9B is a sectional view taken along line YY in FIG. 9A. It is a bottom view of the bearing member of FIG. It is a schematic sectional drawing of the fluid dynamic pressure bearing apparatus provided with the bearing member which concerns on one Embodiment of this-application 2nd invention. It is sectional drawing of the bearing member shown in FIG. It is sectional drawing which shows typically the sizing process included in the manufacturing process of the bearing member shown in FIG. 10, Comprising: The initial stage of the process is shown. It is sectional drawing which shows typically the sizing process included in the manufacturing process of the bearing member shown in FIG. 10, Comprising: It is a figure which shows the middle step of the process. It is sectional drawing which shows typically the sizing process included in the manufacturing process of the bearing member shown in FIG. 10, Comprising: It is a figure which shows the middle step of the process. It is the elements on larger scale of the bearing member concerning a modification. It is a figure which shows typically the modification of a recessed part. It is a figure which shows typically the modification of a recessed part. It is a schematic sectional drawing of the fluid dynamic pressure bearing apparatus provided with the bearing member which concerns on other embodiment of this invention 2nd invention. It is a schematic sectional drawing of the conventional bearing member. It is sectional drawing which shows typically the sizing process included in the manufacturing process of the bearing member shown in FIG. 15, Comprising: The initial stage of the process is shown. It is sectional drawing which shows typically the sizing process included in the manufacturing process of the bearing member shown in FIG. 15, Comprising: It is a figure which shows the middle step of the process. It is sectional drawing which shows typically the sizing process included in the manufacturing process of the bearing member shown in FIG. 15, Comprising: It is a figure which shows the middle step of the process. It is sectional drawing of the conventional bearing member. It is sectional drawing of the conventional bearing member.

Hereinafter, an embodiment of the first invention of the present application will be described with reference to FIGS.

The fan motor shown in FIG. 1 is fixed to the fluid dynamic pressure bearing device 1, a motor base 6, a stator coil 5 fixed to the motor base 6, a rotor 3 having blades (not shown), and the rotor 3. A stator magnet 5 and a rotor magnet 4 facing each other via a radial gap are provided. The housing 7 of the fluid dynamic bearing device 1 is fixed to the inner periphery of the motor base 6, and the rotor 3 is fixed to one end of the shaft member 2 of the fluid dynamic bearing device 1. In the fan motor configured as described above, when the stator coil 5 is energized, the rotor magnet 4 is rotated by the electromagnetic force between the stator coil 5 and the rotor magnet 4, and accordingly, the shaft member 2, the rotor 3, and The rotor magnet 4 rotates and, for example, an axial airflow is generated by the blades provided on the rotor 3.

As shown in FIG. 2, the fluid dynamic bearing device 1 includes a bearing member 8 according to an embodiment of the present invention, a shaft member 2 inserted in the inner periphery of the bearing member 8, and a bearing member 8 on the inner peripheral surface. Is fixed, a seal member 9 disposed in one opening of the housing 7 in the axial direction, and a lid member 10 that closes the other opening of the housing 7 in the axial direction. In the following description of the fluid dynamic bearing device 1, the opening side of the housing 7 in the axial direction is referred to as “upward” and the opposite side is referred to as “downward”. .

The shaft member 2 is formed of a metal material such as stainless steel. The shaft member 2 includes a shaft portion 2a and a flange portion 2b provided at the lower end of the shaft portion 2a. A cylindrical surface 2a1 disposed on the inner periphery of the bearing member 8 and a tapered surface 2a2 disposed above the cylindrical surface 2a1 are provided on the outer peripheral surface of the shaft portion 2a. The outer diameter of the shaft portion 2a (the outer diameter of the cylindrical surface 2a1) is, for example, about 1 to 4 mm.

The housing 7 is formed of a metal or a resin into a cylindrical shape (cylindrical in the illustrated example).

The bearing member 8 includes a first sintered body 81 and a second sintered body 82, and an intermediate sleeve 83 disposed between these axial directions.

The sintered bodies 81 and 82 have a cylindrical shape and are formed of a sintered metal, specifically, a copper-based, iron-based, or copper-iron-based sintered metal. In this embodiment, the sintered bodies 81 and 82 are formed of a sintered metal having the same composition. As shown in FIG. 3, radial bearing surfaces A1 and A2 are provided on the inner peripheral surfaces of the sintered bodies 81 and 82, respectively. In the present embodiment, the first sintered body 81 has a small-diameter inner peripheral surface 81a and a large-diameter inner peripheral surface 81b provided therebelow, and a radial bearing surface in an upper region of the small-diameter inner peripheral surface 81a. A1 is provided. The second sintered body 82 has a small-diameter inner peripheral surface 82a and a large-diameter inner peripheral surface 82b provided thereabove, and a radial bearing surface A2 is provided in a lower region of the small-diameter inner peripheral surface 82a. Provided. Shoulder surfaces 81c and 82c are provided between the small diameter inner peripheral surfaces 81a and 82a and the large diameter inner peripheral surfaces 81b and 82b of the sintered bodies 81 and 82, respectively. In the illustrated example, the shoulder surfaces 81c and 82c are flat surfaces orthogonal to the axial direction. Herringbone-shaped dynamic pressure grooves 81a1 and 82a1 are formed on the radial bearing surfaces A1 and A2 as radial dynamic pressure generating portions, respectively. The region indicated by cross-hatching in the figure represents a hill that is raised to the inner diameter side than the other regions. In the illustrated example, the dynamic pressure grooves 81a1 and 82a1 are both symmetrical in the axial direction. The radial bearing surfaces A1 and A2 including the dynamic pressure grooves 81a1 and 82a1 are collectively formed by sizing described later. Note that the composition or density of the plurality of sintered bodies 81 and 82 or both of them may be different.

In the upper end surface 81d of the first sintered body 81, an annular groove 81d1 and a plurality of radial grooves 81d2 provided at equal intervals in the circumferential direction are formed. A thrust bearing surface B is provided on the lower end surface 82 d of the second sintered body 82. In the present embodiment, a spiral dynamic pressure groove 82d1 as shown in FIG. 4 is formed on the thrust bearing surface B as a thrust dynamic pressure generating portion. The illustrated dynamic pressure groove 82d1 is a pump-in type that pushes the lubricating fluid into the inner diameter side. As shown in FIGS. 2 to 4, a plurality (three in the illustrated example) of axial grooves 81e1 and 82e1 are provided on the outer circumferential surfaces 81e and 82e of the sintered bodies 81 and 82 at equal intervals in the circumferential direction. The numbers and positions of the axial grooves 81e1 and 82e1 and the radial grooves 81d2 are arbitrary, and any or all of them may be omitted if not particularly necessary.

The intermediate sleeve 83 has a smaller amount of load deformation in the axial direction than the sintered bodies 81 and 82. Specifically, the material of the intermediate sleeve 83 is selected so that the axial deformation amount of the intermediate sleeve 83 due to compression during sizing, which will be described later, is smaller than the axial deformation amount of each of the sintered bodies 81 and 82. . The intermediate sleeve 83 of the present embodiment is formed of a material having a larger elastic modulus than the sintered bodies 81 and 82, and is formed of, for example, a melted material. When the sintered metal is pressed, deformation occurs due to the collapse of the internal pores. Therefore, the load deformation amount of the molten metal is generally smaller than the load deformation amount of the sintered metal. In particular, if the intermediate sleeve 83 is formed of a melted material having the same main component as the sintered bodies 81 and 82, the above conditions can be easily satisfied. For example, when the sintered bodies 81 and 82 are formed of a copper-based sintered metal, the intermediate sleeve 83 may be formed of copper or a copper alloy (for example, brass). On the other hand, when the sintered bodies 81 and 82 are formed of iron-based sintered metal, the intermediate sleeve 83 may be formed of iron or an iron alloy (for example, mild steel).

The material of the intermediate sleeve 83 is not limited to the above as long as the load deformation amount is smaller than that of each of the sintered bodies 81 and 82. For example, the sintered bodies 81 and 82 are made of iron-based sintered metal. When forming, the intermediate sleeve 83 may be made of brass in consideration of workability. Further, the intermediate sleeve 83 is not limited to a melted material, and is formed of, for example, a sintered metal having a higher elastic modulus than the sintered bodies 81 and 82 (for example, a sintered metal having a higher density than the sintered bodies 81 and 82). Also good.

The intermediate sleeve 83 has a substantially cylindrical shape, and its inner peripheral surface 83a is a cylindrical surface having no irregularities. The inner peripheral surface 83a of the intermediate sleeve 83 has a larger diameter than the small-diameter inner peripheral surfaces 81a and 82a of the sintered bodies 81 and 82 (specifically, the cylindrical regions 81a2 and 82a2 other than the radial bearing surfaces A1 and A2). The intermediate sleeve 83 has a large-diameter outer peripheral surface 83b and small-diameter outer peripheral surfaces 83c and 83d provided on both axial sides thereof. Shoulder surfaces 83e and 83f are provided between the large-diameter outer peripheral surface 83b and the small-diameter outer peripheral surfaces 83c and 83d, respectively. In the illustrated example, the shoulder surfaces 83e and 83f are flat surfaces orthogonal to the axial direction. The large-diameter outer peripheral surface 83b of the intermediate sleeve 83 has a smaller diameter than the outer peripheral surfaces 81e and 82e of the sintered bodies 81 and 82.

The sintered bodies 81 and 82 and the intermediate sleeve 83 are fixed and integrated with each other in a state before being fixed to the housing 7. In the present embodiment, the sintered bodies 81 and 82 and the intermediate sleeve 83 are fixed by being fitted with a fastening margin in the radial direction. In the illustrated example, the large-diameter inner peripheral surface 81b of the first sintered body 81 and the small-diameter outer peripheral surface 83c on the upper side of the intermediate sleeve 83 are fitted with a margin. Similarly, the large-diameter inner peripheral surface 82b of the second sintered body 82 and the small-diameter outer peripheral surface 83d on the lower side of the intermediate sleeve 83 are fitted with a margin. In the illustrated example, the regions on the shaft end side of the large-diameter inner peripheral surfaces 81b and 82b of the sintered bodies 81 and 82 and the small-diameter outer peripheral surfaces 83c and 83d of the intermediate sleeve 83 are slightly toward the shaft end side, respectively. It is formed in a tapered surface shape with a reduced diameter, and these are taper-fitted. Of course, these may be straight cylindrical surfaces.

The lower end surface 81f of the first sintered body 81 is in contact with the upper shoulder surface 83e of the intermediate sleeve 83, and the upper end surface 82f of the second sintered body 82 is the lower shoulder surface of the intermediate sleeve 83. It is in contact with 83f. The upper end surface 83g of the intermediate sleeve 83 is in contact with the shoulder surface 81c of the first sintered body 81, and the lower end surface 83h of the intermediate sleeve 83 is in contact with the shoulder surface 82c of the second sintered body 82. Yes. Incidentally, either between the lower end surface 81f of the first sintered body 81 and the shoulder surface 83e of the intermediate sleeve 83, or between the shoulder surface 81c of the first sintered body 81 and the end surface 83g of the intermediate sleeve 83. Alternatively, an axial gap may be provided on both sides. Similarly, either between the end surface 82f of the second sintered body 82 and the shoulder surface 83f of the intermediate sleeve 83, or between the shoulder surface 82c of the second sintered body 82 and the end surface 83h of the intermediate sleeve 83. Alternatively, an axial gap may be provided on both sides.

As shown in FIG. 2, the bearing member 8 is fixed to the inner peripheral surface 7 a of the housing 7. Specifically, the outer peripheral surfaces 81e and 82e of the sintered bodies 81 and 82 are fixed to the inner peripheral surface 7a of the housing 7 by appropriate means such as press-fitting, gap bonding, and bonding with press-fitting. However, since the sintered bodies 81 and 82 and the intermediate sleeve 83 constituting the bearing member 8 are integrated with high dimensional accuracy, it is preferably fixed to the housing 7 by gap adhesion in order not to reduce the dimensional accuracy. . A radial clearance is provided between the large-diameter outer peripheral surface 83 b of the intermediate sleeve 83 and the inner peripheral surface 7 a of the housing 7. Via this radial gap and the axial grooves 81e1 and 82e1 of the outer peripheral surfaces 81e and 82e of the sintered bodies 81 and 82, a communication path F through which oil can flow is formed. In the illustrated example, the radial distance between the large-diameter outer peripheral surface 83b of the intermediate sleeve 83 and the inner peripheral surface 7a of the housing 7 is smaller than the radial depth of the axial grooves 81e1 and 82e1 of the sintered bodies 81 and 82. .

The lid member 10 is formed in a disk shape from metal or resin. The lid member 10 is fixed to the lower end of the inner peripheral surface 7 a of the housing 7. In the example of illustration, it fixes to the large diameter part 7a1 provided in the lower end of the internal peripheral surface 7a of the housing 7. FIG. A thrust bearing surface C is provided on the upper end surface 10 a of the lid member 10. A spiral dynamic pressure groove 10a1 as shown in FIG. 5 is formed on the thrust bearing surface C as a thrust dynamic pressure generating portion. The illustrated dynamic pressure groove 10a1 is a pump-in type that pushes the lubricating oil filled in the thrust bearing gap into the inner diameter side.

The seal member 9 is formed in an annular shape with resin or metal and is fixed to the upper end portion of the inner peripheral surface 7a of the housing 7. The lower end surface 9b of the seal member 9 is in contact with the upper end surface of the bearing member 8 (the upper end surface 81d of the upper sintered body 81). An inner peripheral surface 9a of the seal member 9 is opposed to a tapered surface 2a2 provided on the outer peripheral surface of the shaft portion 2a in the radial direction, and a wedge-shaped seal space in which the radial dimension is gradually reduced downward therebetween. S is formed. When the shaft member 2 rotates, the seal space S functions as a capillary force seal and a centrifugal force seal, and prevents leakage of the lubricating oil filled in the housing 7 to the outside. In addition, the wedge-shaped seal space S may be formed by using the outer peripheral surface of the shaft portion 2a as a cylindrical surface and the inner peripheral surface 9a of the seal member 9 as a tapered surface.

潤滑 Lubricating oil as a lubricating fluid is injected into the fluid dynamic bearing device 1 composed of the above components. As a result, the internal space of the fluid dynamic bearing device 1 including the internal pores of the sintered bodies 81 and 82 of the bearing member 8 is filled with the lubricating oil, and the oil level is always maintained within the range of the seal space S. In addition to the lubricating oil, grease or magnetic fluid may be used as the lubricating fluid.

When the shaft member 2 rotates, a radial bearing gap is formed between the radial bearing surfaces A1 and A2 of the sintered bodies 81 and 82 of the bearing member 8 and the outer peripheral surface (cylindrical surface 2a1) of the shaft portion 2a. Then, the pressure of the oil film in the radial bearing gap is increased by the dynamic pressure grooves 81a1 and 82a1 formed on the radial bearing surfaces A1 and A2, and the first radial bearing portion R1 and the second radial bearing portion R1 that support the shaft member 2 rotatably and in a non-contact manner. A radial bearing portion R2 is configured.

At the same time, a thrust bearing gap is formed between the upper end surface 2b1 of the flange portion 2b and the lower end surface 82d (thrust bearing surface B) of the second sintered body 82 of the bearing member 8, and the flange portion 2b A thrust bearing gap is formed between the lower end surface 2b2 and the upper end surface 10a (thrust bearing surface C) of the lid member 10. And the pressure of the oil film of each thrust bearing gap is increased by the dynamic pressure groove 82d1 formed in the lower end surface 82d of the second sintered body 82 and the dynamic pressure groove 10a1 formed in the upper end surface 10a of the lid member 10. Thus, the first thrust bearing portion T1 and the second thrust bearing portion T2 that support the shaft member 2 in a non-contact manner so as to be rotatable in both thrust directions are configured.

In the present embodiment, the space on the outer diameter side of the flange portion 2 b of the shaft member 2 includes a communication path F formed between the outer peripheral surface of the bearing member 8 and the inner peripheral surface 7 a of the housing 7, and the bearing member 8. It communicates with the seal space S via a radial groove 81d2 in the upper end surface (the upper end surface 81d of the first sintered body 81). Thereby, the space on the outer diameter side of the flange portion 2b is always in a state close to atmospheric pressure, and generation of negative pressure in this space can be prevented. One or both of the dynamic pressure grooves 81a1 and 82a1 formed on the inner peripheral surfaces 81a and 82a of the sintered bodies 81 and 82 are asymmetric in the axial direction, and the radial bearing gap is lubricated as the shaft member 2 rotates. A pumping force that pushes oil downward may be generated. In this case, since the lubricating oil circulates in a path of radial bearing clearance → thrust bearing clearance of the first thrust bearing portion T1 → communication path F → radial groove 81d2 → radial bearing clearance, the lubricating oil filled in the housing 7 is filled. Thus, local negative pressure can be reliably prevented from occurring.

Next, a method for manufacturing the bearing member 8 will be described. As shown in FIG. 6, the bearing member 8 forms first and second sintered bodies 81 and 82 and an intermediate sleeve 83, respectively, and sizing the sintered bodies 81 and 82 and these and the intermediate sleeve 83. Are integrated, and thereafter, the internal pores of the sintered bodies 81 and 82 are impregnated with oil. Hereinafter, each process will be described in detail.

The first and second sintered bodies 81 and 82 are respectively a mixing step in which various metal powders are mixed to create a raw material powder, and the raw green powder is compression-molded to form a first green compact and a second green compact. It is formed through a compacting process for forming powder and a sintering process for sintering each compact. In this embodiment, since the sintered bodies 81 and 82 are formed using the same raw material powder, a common raw material powder is created using the same mixing apparatus. Moreover, since the sintering conditions (heating temperature, heating time, heating atmosphere, etc.) of the sintered bodies 81 and 82 are the same, the sintering process is performed using the same sintering apparatus.

In the above compacting step, axial grooves 81e1 and 82e1 are formed on the outer peripheral surface of each compact, and an annular groove 81d1 and a radial groove 81d2 are formed on the end surface of the first compact. Is done. Accordingly, the axial grooves 81e1 and 82e1 are provided on the outer peripheral surfaces of the respective sintered bodies 81 and 82 before the sizing, and the annular grooves 81d1 and the radius are provided on the end surface of the first sintered body 81. A direction groove 81d2 is provided.

The intermediate sleeve 83 is formed by subjecting the melted material to plastic working such as forging or machining such as turning.

The assembly X is configured by combining the sintered bodies 81 and 82 and the intermediate sleeve 83 thus formed. Specifically, an intermediate sleeve 83 is disposed between the sintered bodies 81 and 82 in the axial direction, the large-diameter inner peripheral surface 81b of the first sintered body 81, the small-diameter outer peripheral surface 83c of the intermediate sleeve 83, and the first The large-diameter inner peripheral surface 82b of the second sintered body 82 and the small-diameter outer peripheral surface 83d of the intermediate sleeve 83 are fitted to each other to constitute the assembly X (see FIG. 7A). At this time, the large-diameter inner peripheral surfaces 81b and 82b of the sintered bodies 81 and 82 and the small-diameter outer peripheral surfaces 83c and 83d of the intermediate sleeve 83 are fitted via a radial gap. That is, at this time, the sintered bodies 81 and 82 and the intermediate sleeve 83 are not fixed. At this time, the sintered bodies 81 and 82 and the intermediate sleeve 83 may be temporarily fixed by light press-fitting or the like, or may be completely fixed by press-fitting or adhesion.

Then, by sizing the assembly X, the sintered bodies 81 and 82 are molded to a predetermined size, and at the same time, the sintered bodies 81 and 82 and the intermediate sleeve 83 are fixed and integrated. Hereinafter, the sizing and integration process will be described in detail with reference to FIGS. 7A to 7E.

The mold used in this process includes a die 21, a core rod 22, an upper punch 23 and a lower punch 24. The inner diameter of the die 21 is slightly smaller than the outer diameter of the sintered bodies 81 and 82 before sizing and slightly larger than the outer diameter of the intermediate sleeve 83 (see FIG. 7A). Formed on the outer peripheral surface of the core rod 22 are molding dies 22a and 22b having shapes corresponding to the dynamic pressure grooves 81a1 and 82a1 provided in the sintered bodies 81 and 82 (see FIG. 7B). On the lower end surface of the upper punch 23, a molding die having a shape corresponding to the dynamic pressure groove 82b1 provided in the second sintered body 82 is provided (not shown).

First, as shown in FIG. 7A, the assembly X of the sintered bodies 81 and 82 and the intermediate sleeve 83 is disposed above the die. In the illustrated example, the assembly X is arranged so that the first sintered body 81 is on the lower side and the second sintered body 82 is on the upper side. That is, the assembly X is arranged in a state where the bearing member 8 shown in FIG.

Next, as shown in FIG. 7B, the core rod 22 is inserted into the inner periphery of the assembly X of the sintered bodies 81 and 82 and the intermediate sleeve 83. At this time, the sintered bodies 81 and 82 and the intermediate sleeve 83 and the core rod 22 are fitted via a gap. Then, in a state where the relative position in the axial direction between the assembly X and the core rod 22 is maintained, the end face of the second sintered body 82 is pressed downward by the upper punch 23, so that the assembly X is moved into the die 21. Push around (see FIG. 7C). At this time, the sintered bodies 81 and 82 are press-fitted into the inner periphery of the die 21, and the intermediate sleeve 83 is fitted to the die 21 through a gap. Then, when the lower end surface of the assembly X (the lower end surface in the drawing of the second sintered body 82) is in contact with the upper end surface of the lower punch 24, the upper punch 23 is further lowered slightly, and the sintered bodies 81, 82. And the intermediate sleeve 83 is compressed in the axial direction. At this time, if necessary, the lower punch 24 may be slightly raised.

Thus, by pressing the assembly X into the inner periphery of the die 21, the sintered bodies 81 and 82 are pressed toward the inner diameter. Thereby, the small-diameter inner peripheral surfaces 81a and 82a of the sintered bodies 81 and 82 are pressed against the outer peripheral surface of the core rod 22, and the shapes of the molding dies 22a and 22b are formed on the small-diameter inner peripheral surfaces 81a and 82a of the sintered bodies 81 and 82. After the transfer, the dynamic pressure grooves 81a1 and 82a1 are formed. Further, by pressing the end face 82d of the second sintered body 82 with the upper punch 23, the shape of the molding die provided on the lower end face of the upper punch 23 is transferred to the end face 82d of the sintered body 82, and the dynamic pressure A groove 82d1 is formed.

At the same time, by pushing the assembly X into the gap between the die 21 and the core rod 22, the large-diameter inner peripheral surfaces 81 b and 82 b of the sintered bodies 81 and 82 become the small-diameter outer peripheral surfaces 83 c and 83 d of the intermediate sleeve 83. They are pressed and come into close contact with each other. Thereby, the sintered bodies 81 and 82 and the intermediate sleeve 83 are fixed, and the bearing member 8 is formed. At this time, since the small-diameter outer peripheral surfaces 83c and 83d of the intermediate sleeve 83 are pressed toward the inner diameter via the sintered bodies 81 and 82, the upper and lower ends of the inner peripheral surface 83a of the intermediate sleeve 83 can be slightly reduced in diameter. There is sex. Even in such a case, the inner diameter or the like of the intermediate sleeve 83 is set so that the inner peripheral surface 83 a of the intermediate sleeve 83 does not contact the outer peripheral surface of the core rod 22.

As described above, when the assembly X is pushed into the inner periphery of the die 21, the sintered bodies 81 and 82 and the intermediate sleeve 83 are pressed in the axial direction. At this time, since the internal pores of the sintered bodies 81 and 82 are crushed, the amount of axial deformation (compression) is relatively large. On the other hand, since the intermediate sleeve 83 is formed of a material having a smaller load deformation amount in the axial direction than the sintered bodies 81 and 82, the deformation amount in the axial direction is smaller than that of the sintered bodies 81 and 82. In particular, by forming the intermediate sleeve 83 from a melted material, it hardly deforms due to axial compression. As described above, the deformation amount of the entire bearing member 8 due to sizing is suppressed. Therefore, the axial total length L of the bearing member 8 (see FIG. 3), the axial distance between the radial bearing surfaces A1 and A2, specifically, the maximum surface pressure generating portion (in the illustrated example) of each radial bearing surface A1 and A2. The variation in the product in the axial interval P of the annular hill portion provided at the center in the axial direction is suppressed.

In addition, since the intermediate sleeve 83 is hardly compressed, a compression force is easily applied to the sintered bodies 81 and 82. Therefore, the radial bearing surfaces A1 and A2 of the sintered bodies 81 and 82, and the dynamic pressure grooves 81a1 and 81a1 are further provided. 82a1 can be accurately molded. In particular, in the present embodiment, the thrust bearing surface B and further the dynamic pressure groove 82d1 are formed on the lower end surface 82d of the sintered body 82 by the above sizing process, so that these can be formed with high accuracy. Further, since the intermediate sleeve 83 is not compressed, it becomes easy to apply the same pressing force to the sintered bodies 81 and 82, so that the sintered bodies 81 and 82 are finished with the same dimensional accuracy, and in particular, the radial bearing surface. A difference in inner diameter between A1 and A2 is suppressed.

Thereafter, as shown in FIG. 7D, the bearing member 8, the core rod 22, and the upper and lower punches 23, 24 are raised together and taken out from the inner periphery of the die 21. Further, as shown in FIG. 7E, after the core rod 22 and the upper punch 23 are raised and the core rod 22 is pulled out from the inner periphery of the bearing member 8, the bearing member 8 is discharged from the mold.

The bearing member 8 thus assembled is transferred to the oil impregnation process. Specifically, after the bearing member 8 is immersed in oil under a reduced pressure environment, the internal pores of the sintered bodies 81 and 82 are impregnated with oil by returning to normal pressure. The fluid dynamic bearing device 1 shown in FIG. 2 is completed by assembling the bearing member 8, the shaft member 2, the housing 7, and the seal member 9 and injecting oil into the housing 7.

The present invention is not limited to the above embodiment. Hereinafter, although other embodiment of this invention is described, the site | part which has a function similar to said embodiment attaches | subjects the same code | symbol, and abbreviate | omits duplication description.

For example, the embodiment shown in FIG. 8 is different from the above-described embodiment in the connection state between the sintered bodies 81 and 82 and the intermediate sleeve 83. Specifically, the inner peripheral surfaces and outer peripheral surfaces of the sintered bodies 81 and 82 and the intermediate sleeve 83 have a substantially straight cylindrical shape. Grooves 83g1 and 83h1 are formed in both end faces 83g and 83h of the intermediate sleeve 83. Specifically, as shown in FIGS. 9A to 9C, a plurality of (four in the illustrated example) grooves 83g1 and 83h1 are arranged at equal intervals in the circumferential direction on both end faces 83g and 83h of the intermediate sleeve 83. Each groove 83g1, 83h1 has a gradually narrowing circumferential width as it goes to the outer diameter side. In FIGS. 9A and 9C, in the both end faces 83g and 83h of the intermediate sleeve 83, the formation regions of the grooves 83g1 and 83h1 are dotted.

On the other hand, the end surfaces 81f and 82f of the sintered bodies 81 and 82 are provided with convex portions 81f1 and 82f1 that enter the grooves 83g1 and 83h1 of the intermediate sleeve 83, respectively. The grooves 83g1 and 83h1 of the intermediate sleeve 83 and the projections 81f1 and 82f1 of the sintered bodies 81 and 82 are in close contact with each other in the direction perpendicular to the axis, whereby the sintered bodies 81 and 82 and the intermediate sleeve 83 are fixed. The In the present embodiment, the convex portions 81f1 and 82f1 of the sintered bodies 81 and 82 are in close contact with the side surfaces and the bottom surface on both sides in the circumferential direction of the grooves 83g1 and 83h1 of the intermediate sleeve 83. Is engaged. The shapes of the grooves 83g1 and 83h1 are not limited to the above, and for example, a circumferential annular groove, a radial groove, or both of them may be provided.

The above-described bearing member 8 can be manufactured by the following procedure. First, sintered bodies 81 and 82 having flat end surfaces not provided with the convex portions 81f1 and 82f1 are formed. The intermediate sleeve 83 is formed in a finished product shape shown in FIGS. The intermediate sleeve 83 is formed of, for example, a molten material so that the amount of load deformation in the axial direction is smaller than that of each of the sintered bodies 81 and 82. The intermediate sleeve 83 and the sintered bodies 81 and 82 are combined to form an assembly X, and the assembly X is sized in the same procedure as shown in FIG. At this time, by pressing the assembly X from both sides in the axial direction, the end faces 81f and 82f of the sintered bodies 81 and 82 are pressed against the flat end faces 83g and 83h of the intermediate sleeve 83, and the material of the sintered bodies 81 and 82 A part of the fluid flows plastically into the grooves 83g1 and 83h1 of the intermediate sleeve 83. Thus, convex portions 81f1 and 82f1 that enter the grooves 83g1 and 83h1 of the intermediate sleeve 83 are formed on the end surfaces 81f and 82f of the sintered bodies 81 and 82, and the sintered bodies 81 and 82 and the intermediate sleeve 83 are fixed. The

In the above embodiment, the case where the sintered bodies 81 and 82 are press-fitted into the die 21 when sizing the assembly X is shown, but the present invention is not limited to this. For example, the assembly X is inserted into the inner periphery of the die 21 through a radial gap, and in this state, the assembly X is compressed from both sides in the axial direction to expand the sintered bodies 81 and 82 in the radial direction. You may make it press on the die | dye 21 and the core rod 22. FIG.

In the above embodiment, the case where there are two sintered bodies and one intermediate sleeve is shown. However, the present invention is not limited to this. For example, three or more sintered bodies or two or more intermediate sleeves are provided. Or you may.

Further, the radial dynamic pressure generating portions provided on the radial bearing surfaces A1 and A2 of the bearing member 8 are not limited to the herringbone-shaped dynamic pressure grooves 81a1 and 82a1, but include, for example, spiral-shaped dynamic pressure grooves and axial directions. Alternatively, a step-shaped dynamic pressure groove extending in the direction may be used. Further, the thrust dynamic pressure generating portions provided on the thrust bearing surface B of the bearing member 8 and the thrust bearing surface C of the lid member 10 are not limited to the spiral-shaped dynamic pressure grooves 82d1 and 10a1, but have a herringbone shape, a step shape, or the like. Other shapes of dynamic pressure grooves may be used.

Further, the flange portion 2b of the shaft member 2 is omitted, a spherical convex portion is provided at the lower end of the shaft portion 2a, and the convex bearing and the upper end surface 10a of the lid member 10 are brought into contact with each other to thereby provide a thrust bearing portion (pivot bearing). May be configured. In this case, the dynamic pressure groove 82d1 provided on the end surface of the bearing member 8 and the dynamic pressure groove 10a1 provided on the upper end surface 10a of the lid member 10 are omitted.

In the above embodiment, the case where the dynamic pressure generating portions (dynamic pressure grooves) are formed on the inner peripheral surface, the lower end surface of the bearing member 8 and the upper end surface 10a of the lid member 10 has been described. A dynamic pressure generating portion may be formed on the outer peripheral surface (cylindrical surface 2a1) of the shaft member 2 facing the surface through a bearing gap, the upper end surface 2b1 and the lower end surface 2b2 of the flange portion 2b. Further, both the inner peripheral surface of the bearing member 8 and the outer peripheral surface of the shaft member 2 may be cylindrical surfaces to constitute a perfect circle bearing. In this case, a dynamic pressure action is generated in the lubricating fluid in the radial bearing gap due to the swing of the shaft member 2.

In the above-described embodiment, the shaft rotation type fluid dynamic pressure bearing device in which the shaft member 2 rotates is shown. However, the present invention is not limited thereto, and the shaft member 2 is fixed, and the shaft fixed type in which the bearing member 8 side rotates. The present invention can also be applied to a fluid dynamic bearing device or a fluid dynamic bearing device in which both the shaft member 2 and the bearing member 8 rotate.

Further, the fluid dynamic pressure bearing device described above can be applied not only to a fan motor but also to an HDD spindle motor, a polygon scanner motor of a laser beam printer, a color wheel of a projector, and the like.

Next, an embodiment of the second invention of the present application will be described with reference to FIGS.

A fluid dynamic bearing device 101 shown in FIG. 10 has a bearing member 103 according to an embodiment of the present invention, a shaft member 102 inserted in the inner periphery of the bearing member 103, and adhesion or press-fit adhesion (adhesion in a press-fit state). And a cylindrical housing 104 in which the bearing member 103 is fixed to the inner periphery by appropriate means. The shaft member 102 is supported so as to be relatively rotatable in the radial direction by radial bearing portions R1 and R2 formed at two positions spaced apart in the axial direction. The bearing member 103 includes a plurality of cylindrical bodies (in the present embodiment, a first cylindrical body 131 and a second cylindrical body 132) that are arranged in a row in the axial direction. Although not shown in detail, the internal space of the housing 104 is filled with lubricating oil as a lubricating fluid. In the following, for the sake of convenience, the description will proceed with the side on which the first cylindrical body 131 is disposed as the upper side and the side on which the second cylindrical body 132 is disposed on the lower side, but the fluid dynamic pressure bearing device 101 (bearing member 103). However, there is no limitation on the use mode.

The shaft member 102 is formed of, for example, a metal material such as stainless steel, and a portion of the outer peripheral surface 102a that faces the inner peripheral surface of the bearing member 103 is formed as a smooth cylindrical surface without unevenness.

The first cylindrical body 131 and the second cylindrical body 132 constituting the bearing member 103 are both made of a sintered metal porous body mainly composed of copper or iron and formed in a substantially cylindrical shape. In the present embodiment, the yield point of the first cylindrical body 131 is relatively small, and the yield point of the second cylindrical body 132 is relatively large. In short, the second cylindrical body 132 is formed of a sintered metal having a higher strength than the first cylindrical body 131. Thus, the sintered metal cylinders 131 and 132 having different yield points, for example, make the composition of the raw material powders different from each other, make the molding pressures different when obtaining the green compact of the raw material powder, or It can be obtained by adopting means such as different sintering conditions.

A cylinder that forms a radial bearing gap of the radial bearing portion R1 on the inner peripheral surface 131a of the first cylindrical body 131 between the outer peripheral surface 102a of the opposing shaft member 102 when the shaft member 102 and the bearing member 103 are relatively rotated. A radial bearing surface A1 is provided. As shown in FIG. 11, a dynamic pressure generating portion (radial dynamic pressure generating portion) 108 for generating a dynamic pressure action on the lubricating oil in the radial bearing gap of the radial bearing portion R1 is formed on the radial bearing surface A1. ing. The illustrated dynamic pressure generator 108 includes a plurality of upper dynamic pressure grooves 108a1 inclined with respect to the axial direction, a plurality of lower dynamic pressure grooves 108a2 inclined in a direction opposite to the upper dynamic pressure grooves 108a1, and a dynamic pressure The grooves 108a1 and 108a2 are divided into convex hills, and the dynamic pressure grooves 108a1 and 108a2 are arranged in a herringbone shape as a whole. The hill portion includes an inclined hill portion 108b provided between the dynamic pressure grooves adjacent to each other in the circumferential direction, and an annular hill portion 108c that is provided between the upper and lower dynamic pressure grooves 108a1 and 108a2 and has substantially the same diameter as the inclined hill portion 108b. Consists of.

The inner peripheral surface 132a of the second cylindrical body 132 is partitioned into a relatively small-diameter small-diameter internal peripheral surface 132a1 and a relatively large-diameter large-diameter internal peripheral surface 132a2. A cylindrical radial bearing surface that forms a radial bearing gap of the radial bearing portion R2 between the small-diameter inner peripheral surface 132a1 and the outer peripheral surface 102a of the opposing shaft member 102 when the shaft member 102 and the bearing member 103 rotate relative to each other. A2 is provided. As shown in FIG. 11, the radial bearing surface A2 is formed with a dynamic pressure generating portion (radial dynamic pressure generating portion) 8 for generating a dynamic pressure action on the lubricating oil in the radial bearing gap of the radial bearing portion R2. ing. The dynamic pressure generation unit 108 has the same configuration as the dynamic pressure generation unit 108 provided on the inner peripheral surface 131a (radial bearing surface A1) of the first cylindrical body 131. The large-diameter inner peripheral surface 132a2 is disposed between the two radial bearing surfaces A1 and A2 to form a middle escape portion B.

It should be noted that the shape of the dynamic pressure generator 108 provided on both the radial bearing surfaces A1 and A2 is merely an example, and it is of course possible to adopt other known dynamic pressure generators 108.

The first cylindrical body 131 and the second cylindrical body 132 constituting the bearing member 103 are coupled by a concave and convex fitting structure 107 formed between the cylindrical bodies 131 and 132. The concave-convex fitting structure 107 is an upper end surface of the second cylindrical body 132 among two surfaces (here, the lower end surface 131b of the first cylindrical body 131 and the upper end surface 132c of the second cylindrical body 132) facing each other in the axial direction. A convex raised portion 106 (convex portion) provided on the lower end surface 131b of the first cylindrical body 131 is brought into close contact with the inner wall surface of the concave portion 105 provided in 132c. In the present embodiment, the concave portion 105 and the convex raised portion 106 in close contact with the concave portion 105 each have an annular shape. The annular region excluding the portion where the raised portion 106 is formed in the lower end surface 131b of the first cylindrical body 131 and the annular region excluding the portion where the recess 105 is formed in the upper end surface 132c of the second cylindrical body 132 are These are all formed on a flat surface extending in a direction orthogonal to the axis (axial direction), and the two flat surfaces are in close contact with each other.

As described above, the radial fitting surfaces A1 and A2 having the dynamic pressure generating portion 108 are provided on the inner peripheral surfaces of the two cylindrical bodies 131 and 132, respectively, and the concave-convex fitting structure formed between the two cylindrical bodies 131 and 132. The bearing member 103 formed by coupling the two cylindrical bodies 131 and 132 by the 107 is a first cylindrical body 131 and a second cylindrical body 132 that are arranged in a line in the axial direction (strictly speaking, each of the first and second cylindrical bodies 131 and 132 has the above-described configuration by sizing. The first cylindrical material 131 ′ and the second cylindrical material 132 ′) finished into the first and second cylindrical bodies 131 and 132 are obtained by sizing. Hereinafter, the sizing process will be described in detail with reference to FIGS. 12A to 12C.

As shown in FIGS. 12A to 12C, the sizing process is performed using a sizing die 110 including a core rod 111, a cylindrical die 112, and a pair of upper and lower punches 113 and 114 arranged coaxially. Although the detailed illustration is omitted, an uneven mold corresponding to the shape of the dynamic pressure generating portions 108 and 108 (having the radial bearing surfaces A1 and A2) is vertically spaced on the outer peripheral surface of the core rod 111. It is provided in two places.

Next, the first and second cylindrical materials 131 'and 132' used in the sizing process will be described. A first cylindrical material 131 ′ shown in FIG. 12A is finished to a first cylindrical body 131 having the above-described configuration by sizing, and a radial bearing surface A1 (dynamic pressure generating portion 108) is provided on the inner peripheral surface thereof. Absent. Further, in the first cylindrical material 131 ′, the lower end surface 131 b ′ that becomes the lower end surface 131 b of the first cylindrical body 131 after sizing is formed as a flat surface in the direction orthogonal to the axis. The second cylindrical material 132 ′ is finished to the second cylindrical body 132 having the above-described configuration by sizing, and the inner peripheral surface thereof is a relatively small-diameter small-diameter inner peripheral surface and a relatively large-diameter large-diameter inside. Although divided into a peripheral surface, the radial bearing surface A2 (dynamic pressure generating portion 108) is not provided on the small-diameter inner peripheral surface. However, of the second cylindrical material 132 ′, an annular recess 105 is provided on the upper end surface 132 c ′ which becomes the upper end surface 132 c of the second cylindrical body 132 after sizing. The first and second cylindrical materials 131 ′ and 132 ′ having the above configuration are both sintered metal porous bodies obtained by sintering a green compact of raw material powder. The first cylindrical material 131 ′ of this embodiment has a yield point smaller than that of the second cylindrical material 132 ′.

In the above configuration, first, as shown in FIG. 12A, both cylindrical materials 131 ′ and 132 ′ are arranged on the upper end surface 112 a of the die 112 so as to be connected in the axial direction (superposed vertically). More specifically, the second cylindrical material 132 ′ is placed on the upper end surface 112a of the die 112 in an upright posture with the upper end surface 132c ′ provided with the recess 105 on the upper side, and the lower end surface 131b ′ is placed on the lower side. The first cylindrical material 131 ′ is placed on the second cylindrical material 132 ′ in the standing posture. Then, the core rod 111 is inserted into the inner circumference of both cylindrical materials 131 ′ and 132 ′.

Next, as shown in FIG. 12B, by lowering the core rod 111 and the upper punch 113, both cylindrical materials 131 ′ and 132 ′ are press-fitted into the inner periphery of the die 112, and the outer peripheral surfaces of both cylindrical materials 131 ′ and 132 ′. Is restrained. After that, as shown in FIG. 12C, when the core rod 111 and the upper punch 113 are further lowered and both the cylindrical materials 131 ′ and 132 ′ are compressed in the axial direction by the upper punch 113 and the lower punch 114, both the cylindrical materials 131 ′ and 132 ′. Is expanded and deformed in the radial direction, and the outer peripheral surface and inner peripheral surface of both cylindrical materials 131 ′ and 132 ′ are pressed against the inner peripheral surface 112 b of the die 112 and the outer peripheral surface 111 a of the core rod 111, respectively. Thereby, the outer peripheral surface and inner peripheral surface of both cylindrical materials 131 ′ and 132 ′ are deformed following the inner peripheral surface 112b of the die 112 and the outer peripheral surface 111a of the core rod 111, and the inner peripheral surface of the first cylindrical material 131 ′. The radial bearing surfaces A1 and A2 having the dynamic pressure generating portion 108 are formed on the inner peripheral surface (small inner peripheral surface) of the second cylindrical material 132 ′. Then, when the core rod 111 and the upper punch 113 are further lowered, the lower end surface 131b ′ of the first cylindrical material 131 ′ protrudes from the portion facing the concave portion 105 provided on the upper end surface 132c ′ of the second cylindrical material 132 ′. A raised portion 106 is formed, and the raised portion 106 is in close contact with the inner wall surface of the recess 105. As a result, the concave-convex fitting structure 107 is formed between the cylindrical materials 131 ′ and 132 ′.

Although illustration is omitted, after forming the concave-convex fitting structure 107 as described above, for example, the core rod 111 and the upper and lower punches 113 and 114 are raised integrally to form both cylindrical materials 131 ′ and 132 ′. After the integrated product is discharged to the outside of the die 112, the upper punch 113 and the core rod 111 are further raised. As a result, the radial bearing surface A1 having the dynamic pressure generating portion 108 is formed on the inner peripheral surface 131a of the first cylindrical body 131, and the inner peripheral surface 132a (small diameter inner peripheral surface 132a1) of the second cylindrical body 132 is moved. A bearing member 103 is obtained in which a radial bearing surface A2 having a pressure generating portion 108 is formed, and the two cylindrical bodies 131 and 132 are coupled by the concave-convex fitting structure 107.

In the fluid dynamic bearing device 101 having the above-described configuration, when the shaft member 102 and the bearing member 103 rotate relative to each other, the radial bearing surfaces A1 and A2 that are spaced apart at two locations on the inner periphery of the bearing member 103, and these A radial bearing gap is formed between the shaft member 102 and the outer peripheral surface 102a facing each other. As the shaft member 102 and the bearing member 103 rotate relative to each other, the pressure of the oil film formed in the radial bearing gaps is increased by the dynamic pressure action of the dynamic pressure generating portions 108 and 108. As a result, the shaft member 102 is moved in the radial direction. Radial bearing portions R1 and R2 that are supported in a non-contact manner so as to be relatively rotatable are formed at two locations separated in the axial direction. At this time, a cylindrical lubricating oil reservoir is formed between the two radial bearing gaps by providing the cylindrical surface escape portion B on the inner periphery of the bearing member 103 (second cylindrical body 132). Therefore, it is possible to prevent as much as possible an oil film breakage between the radial bearing gaps, that is, a reduction in bearing performance of the radial bearing portions R1 and R2.

Although not shown, the fluid dynamic bearing device 101 described above includes, for example, (1) a spindle motor for a disk device, (2) a polygon scanner motor for a laser beam printer, or (3) a fan for a PC. Used as a bearing device for a motor such as a motor. In the case of (1), for example, a disk hub having a disk mounting surface is provided integrally or separately on the shaft member 102, and in the case of (2), for example, a polygon mirror is provided integrally or separately on the shaft member 102. . In the case of (3), for example, a fan having blades on the shaft member 102 is provided integrally or separately.

As described above, in the bearing member 103 according to the present invention, any one of the lower end surface 131b of the first cylindrical body 131 and the upper end surface 132c of the second cylindrical body 132 facing each other in the axial direction [ Here, with respect to the concave portion 105 provided only on the upper end surface 132c (132c ′)], the convex raised portion 106 generated on the other end surface [here, the lower end surface 131b (131b ′)] is brought into close contact with the sizing. The first and second cylindrical bodies 131 and 132 that are adjacent in the axial direction are joined together by the concave-convex fitting structure 107 formed in (1).

If the cylindrical bodies 131 and 132 adjacent in the axial direction are coupled to each other by such an uneven fitting structure 107, a convex raised portion 106 that is in close contact with the concave portion 105 is formed on the lower end surface 131b ′ along with sizing. As long as it can be made, the shape of the lower end surface 131b ′ of the first cylindrical material 131 ′ before the sizing can be arbitrarily set. Therefore, before the sizing, the entire lower end surface 131b ′ of the first cylindrical material 131 ′ is flat with the direction orthogonal to the axis, that is, the upper end surface 132c ′ of the second cylindrical material 132 ′ (as described above). It can be formed into a shape that does not engage (in the radial direction). In this case, until the sizing progresses to some extent, the radial movement of one of the two cylinders adjacent in the axial direction is not restricted by the presence of the other, so the first cylindrical material 131 ′ and the second cylinder The forming area of the radial bearing surface on the inner peripheral surface of the cylindrical material 132 ′ can be appropriately pressed against the outer peripheral surface 111 a of the core rod 111. Therefore, while the radial bearing surfaces A1 and A2 having the dynamic pressure generating portion 108 are formed with a predetermined accuracy, the cylindrical bodies adjacent to each other in the axial direction are properly aligned between the radial bearing surfaces A1 and A2. The bearing member 103 in which 131 and 132 are appropriately coupled can be obtained.

In particular, in the present embodiment, of the two cylindrical bodies 131 and 132 (cylindrical materials 131 ′ and 132 ′) to be joined, the yield of the second cylindrical body 132 (second cylindrical material 132 ′) provided with the recess 105 is provided. Since the point is relatively large, it is possible to prevent as much as possible a situation in which the concave portion 105 of the second cylindrical body 132 is deformed with sizing and the cylindrical bodies 131 and 132 are not properly coupled. Can do.

The bearing member 103 according to an embodiment of the present invention and the fluid dynamic pressure bearing device 101 including the bearing member 103 have been described above, but various changes have been made to the bearing member 103 without departing from the gist of the present invention. Can be applied.

For example, in the embodiment described above, the concave portion 105 for forming the concave / convex fitting structure 107 has two end surfaces (the lower end surface 131b of the first cylindrical body 131b and the second cylindrical body 132 of the first cylindrical body 131) facing each other in the axial direction. Of the upper end surface 132c), the upper end surface 132c is configured by an annular groove provided at a substantially central portion in the radial direction. Also good. FIG. 13A specifically shows an example of this, and the concave portions 105 each formed of an annular groove are provided at two locations spaced in the radial direction of the upper end surface 132 c of the second cylindrical body 132. In this case, the convex raised portions 106 that are in close contact with the concave portion 105 are formed at two locations that are spaced apart from each other in the radial direction of the lower end surface 131 b of the first cylindrical body 131.

Further, the concave portion 105 for forming the concave / convex fitting structure 107 can be constituted by a groove having a circumferential end as shown in FIGS. 13B and 13C, for example, in addition to the annular groove. In this case, after the concave / convex fitting structure 107 is formed, the possibility that the cylindrical bodies 131 and 132 adjacent in the axial direction rotate relative to each other around the axis can be reduced. FIG. 13B is an example of the case where the concave portion 105 is configured by a radial groove whose groove width gradually decreases toward the outer diameter side, and FIG. 13C is the case where the concave portion 105 is configured by a radial groove having a constant groove width. It is an example of a case. Of course, the shape of the recess 105 is not limited to that described above, and the recess 105 may be configured by, for example, a spiral groove or dimple (a recess having a substantially semicircular cross section) (not shown).

Further, the concave-convex fitting structure 107 includes a first and a first arranged in an axial direction with respect to the concave portion 105 provided on the lower end surface 131b of the first cylindrical body 131 (the lower end surface 131b ′ of the first cylindrical material 131 ′). As the two cylindrical bodies 131 and 132 (first and second cylindrical materials 131 ′ and 132 ′) are sized, the upper end surface 132c of the second cylindrical body 132 (the upper end surface 132c ′ of the second cylindrical material 132 ′). It is also possible to form the ridges 106 by bringing them into close contact with each other.

Further, the middle escape portion B may be configured not by the second cylindrical body 132 but by the inner peripheral surface of the first cylindrical body 131, or by both the inner peripheral surfaces of the first and second cylindrical bodies 131 and 132. It may be configured.

The bearing member 103 is connected in the axial direction as shown in FIG. 14, in addition to the two cylindrical bodies (first and second cylindrical bodies 131 and 132) connected in the axial direction. It is also possible to configure by connecting three cylindrical bodies arranged in the same manner. More specifically, the bearing member 103 shown in FIG. 14 is disposed at one end (upper end) in the axial direction, and includes a first cylindrical body 131 made of sintered metal having a radial bearing surface A1 on the inner peripheral surface 131a, and an axial direction. And a second cylindrical body 132 made of sintered metal having a radial bearing surface A2 on the inner peripheral surface 132a, and a third cylindrical body 133 disposed therebetween. A middle escape portion B is formed by the inner peripheral surface 133 a of the third cylindrical body 133. The first cylindrical body 131 and the third cylindrical body 133 that are adjacent in the axial direction are joined together by an uneven fitting structure 107 formed therebetween. In addition, the third cylindrical body 133 and the second cylindrical body 132 that are adjacent in the axial direction are coupled together by the concave-convex fitting structure 107 formed therebetween.

In the embodiment shown in FIG. 14, the convex raised portion 106 formed on the lower end surface 131 b of the first cylindrical body 131 is formed with respect to the concave portion 105 formed of an annular groove provided on the upper end surface 133 b of the third cylindrical body 133. By bringing them into close contact, the concave-convex fitting structure 107 that joins the first and third cylindrical bodies 131 and 133 is formed. In addition, the convex ridge 106 formed on the upper end surface 132c of the second cylindrical body 132 is brought into close contact with the concave portion 105 formed of an annular groove provided on the lower end surface 133c of the third cylindrical body 133, whereby the first A concave-convex fitting structure 107 that couples the second and third cylindrical bodies 132 and 133 is formed. Of course, either one or both of these two concave-convex fitting structures 107 can be formed by a concave portion 105 as shown in FIGS. 13A to 13C and a convex raised portion 106 in close contact therewith.

Although detailed illustration is omitted, the bearing member 103 shown in FIG. 14 is also obtained by sizing the three cylindrical bodies 131 to 133 arranged in the axial direction in the same manner as the bearing member 103 shown in FIG. . That is, both radial bearing surfaces A1 and A2 are formed by the above sizing. With this sizing, convex raised portions 106 are formed on the lower end surface 131b of the first cylindrical body 131 and the upper end surface 132b of the second cylindrical body 132, and these raised portions 106 are respectively connected to the third cylindrical body 133. By bringing the concave and convex portions 105 and 105 provided in the upper end surface 133b and the lower end surface 133c into close contact with each other, the concave-convex fitting structure 107 that couples the cylindrical bodies adjacent in the axial direction is formed.

In this embodiment, the concave portion 105 is deformed with sizing and the possibility that the predetermined concave-convex fitting structure 107 cannot be obtained is reduced. Therefore, the third cylindrical body 133 having the concave portion 105 is replaced with the first cylindrical body 131 and the first cylindrical body 133. It is made of a material having a yield point larger than that of the two cylinders 132. The third cylindrical body 133 may be formed of a sintered metal porous body in the same manner as the first and second cylindrical bodies 131 and 132, but here, the third cylindrical body 133 is made of a molten material such as stainless steel or brass. A cylindrical body 133 is formed. In this case, the amount of lubricating oil to be filled in the internal space of the fluid dynamic bearing device 101 (housing 104) can be reduced as compared with the case where the third cylindrical body 133 is formed of sintered metal. This is advantageous in reducing the cost of the apparatus 101.

Although not shown in the drawings, the bearing member 103 described above can be used not only for radial loads but also for supporting thrust loads. In this case, a thrust bearing surface is provided on one or both of the upper end surface 131c of the first cylindrical body 131 and the lower end surface 132b of the second cylindrical body 132 in accordance with the shape of the shaft to be supported (the shaft member 102). be able to. Like the radial bearing surface, the thrust bearing surface can be molded at the same time as sizing a plurality of cylindrical bodies arranged in a row in the axial direction, and the thrust bearing surface has a dynamic pressure such as a dynamic pressure groove. A generator (thrust dynamic pressure generator) may be provided. The thrust dynamic pressure generating portion can be molded simultaneously with sizing the plurality of cylindrical bodies.

In the embodiment described above, in the sizing process for manufacturing the bearing member 103, the radial dynamic pressure generating portion 108 is molded on the inner peripheral surface of the bearing member 103. 108 may be provided on the outer peripheral surface 102 a of the shaft member 102 facing the inner peripheral surface of the bearing member 103.

Further, as described above, the present invention is not limited to the case where the bearing member 103 is constituted by two or three cylindrical bodies arranged in a row in the axial direction, but also four or more pieces arranged in a row in the axial direction. The present invention is also applicable when the bearing member 103 is formed of a cylindrical body.

The embodiment of the first invention of the present application and the embodiment of the second invention of the present application described above can be appropriately combined. That is, the configuration shown in the embodiment of the first invention of the present application can be applied to the embodiment of the second invention of the present application, and the configuration shown in the embodiment of the second invention of the present application is applied to the embodiment of the first invention of the present application. It can also be applied to.

DESCRIPTION OF SYMBOLS 1 Fluid dynamic pressure bearing apparatus 2 Shaft member 7 Housing 8 Bearing member 81 1st sintered body 82 2nd sintered body 83 Intermediate sleeve 9 Seal member 10 Lid member 21 Die 22 Core rod 23 Upper punch 24 Lower punch A1, A2 Radial bearing surface B, C Thrust bearing surface F Communication path R1, R2 Radial bearing portion T1, T2 Thrust bearing portion S Seal space X Assembly

Claims (13)

1. A bearing member integrally including a plurality of sintered bodies having a bearing surface on an inner peripheral surface and an intermediate sleeve disposed between the axial directions of the plurality of sintered bodies,
   A bearing member, wherein an axial load deformation amount of the intermediate sleeve is smaller than an axial load deformation amount of each sintered body.
2. The bearing member according to claim 1, wherein the intermediate sleeve is formed of a molten material.
3. The bearing member according to claim 2, wherein the melted material is made of a metal similar to the plurality of sintered bodies.
4. The bearing member according to any one of claims 1 to 3, wherein the intermediate sleeve is formed of a material having a larger elastic modulus than each sintered body.
5. The bearing member according to any one of claims 1 to 4, wherein a radial dynamic pressure generating portion is formed on a bearing surface of the plurality of sintered bodies.
6. The bearing member according to any one of claims 1 to 5, a shaft member inserted into an inner periphery of the bearing member, and a radial between a bearing surface of each sintered body and an outer peripheral surface of the shaft member A fluid dynamic bearing device comprising a radial bearing portion that supports the shaft member so as to be relatively rotatable with a fluid film generated in a bearing gap.
7. 7. A motor comprising the fluid dynamic pressure bearing device according to claim 6, a stator fixed to one of the shaft member and the bearing member, and a rotor magnet fixed to the other of the shaft member and the bearing member.
8. Forming a plurality of cylindrical sintered bodies;
   Forming an intermediate sleeve having a smaller amount of load deformation in the axial direction than each sintered body;
   The assembly is inserted into the inner periphery of the die in a state where the core rod is inserted into the inner periphery of the assembly including the plurality of sintered bodies and the intermediate sleeve arranged between the axial directions. And pressing the inner peripheral surfaces of the plurality of sintered bodies against the outer peripheral surface of the core rod by pressing from both sides in the axial direction, and forming a bearing surface on the inner peripheral surfaces of the plurality of sintered bodies. Manufacturing method of bearing member.
9. The method for manufacturing a bearing member according to claim 8, wherein the intermediate sleeve is formed of a molten material.
10. The method for manufacturing a bearing member according to claim 9, wherein the melted material is made of a metal similar to the plurality of sintered bodies.
11. The method for manufacturing a bearing member according to any one of claims 8 to 10, wherein the intermediate sleeve is formed of a material having a larger elastic modulus than each sintered body.
12. A radial dynamic pressure generating portion is formed on the bearing surfaces of the plurality of sintered bodies by providing a molding die on the outer peripheral surface of the core rod and pressing the inner peripheral surfaces of the plurality of sintered bodies against the molding die. The method for producing a bearing member according to any one of 8 to 11.
13. Preliminarily providing recesses on both end surfaces in the axial direction of the intermediate sleeve, and providing flat surfaces on the end surfaces of each sintered body,
    By pressing the assembly from both sides in the axial direction, the end surface of each sintered body having the concave portion is pressed against the flat surface, and a raised portion that is closely fitted to the concave portion is formed on the end surface of each sintered body. 13. The method for manufacturing a bearing member according to claim 8, wherein the intermediate sleeve and each sintered body are fixed by doing so.
    

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