JP2022055700A - Manufacturing method of fluid dynamic pressure bearing device - Google Patents

Abstract

To stably secure a desired fixing force between a bottomed cylindrical housing and a bearing member which adhere to each other with a clearance.SOLUTION: When fixing a bearing member 8 which forms a radial bearing clearance along an internal peripheral face 8a to an internal periphery of a bottomed cylindrical housing 7 by clearance-adhesion, a plurality of points which are separated in a peripheral direction of the internal peripheral face 8a of the bearing member 8 are contact-supported by a support pin 24 arranged at a first metal mold 21 out of first and second metal molds 21, 22 which relatively approximate each other and separably move, an external peripheral face 7c of the housing 7 is constricted by the second metal mold 22, and after that, a bottom-side space 10 which is formed between a lower end face 8b of the bearing member 8 and an inner bottom face 7b of the housing 7 accompanied by the relative approach/movement of both the metal molds 21, 22, and an opening-side space which is formed of an upper end face 8c of the bearing member 8 are maintained in a communicative state via ventilation paths 30 which are formed of a region (connection face 24b) except for support parts 24b of the bearing member 8 out of an external peripheral face of the support pin 24 up until the relative approach/movement of both the metal molds 21, 22 is completed.SELECTED DRAWING: Figure 6

Description

The present invention relates to a method for manufacturing a fluid dynamic bearing device.

As is well known, the fluid dynamic bearing device has features such as high speed rotation, high rotation accuracy and low noise. Therefore, the fluid dynamic bearing device is, for example, a bearing device for a spindle motor incorporated in a disk drive device such as an HDD, a fan motor incorporated in a PC or the like, or a polygon scanner motor incorporated in a laser beam printer. It is used.

For example, FIG. 8 of Patent Document 1 below includes a bottomed tubular housing and a cylindrical bearing member forming a radial bearing gap of the radial bearing portion on the inner peripheral surface, and the bearing member is the inner circumference of the housing. Disclosed is a fluid dynamic bearing device fixed by gap adhesion. In this type of hydrodynamic bearing device, the coaxiality between the inner peripheral surface of the bearing member and the outer peripheral surface of the housing greatly affects the bearing performance (particularly the bearing performance of the radial bearing portion). Therefore, in Patent Document 1, when the bearing member is gap-bonded to the inner circumference of the housing (to produce an assembly in which the bearing member is gap-bonded to the inner circumference of the housing), the outer peripheral surfaces of the bearing members facing each other and the inside of the housing are manufactured. With the adhesive gap between the peripheral surface and the peripheral surface filled with adhesive, the two restraint surfaces provided in the assembly device (the cylindrical outer peripheral surface for restraining the cylindrical inner peripheral surface of the bearing member, and the taper of the housing). The degree of coaxiality between the outer peripheral surface (tapered inner peripheral surface for restraining the outer peripheral surface) is controlled.

Japanese Unexamined Patent Publication No. 2008-25739

As in Patent Document 1, when the bearing member is gap-bonded to the inner circumference of the housing, the inner peripheral surface of the bearing member is restrained over the entire circumference by the cylindrical outer peripheral surface of the support pin provided in the assembly device. It has been found that it is difficult to stably secure a desired fixing force (adhesive strength) between the bearing member and the bearing member. The main reason for such inconvenience is that the gap width of the bonding gap is usually set to a minute width of about several tens of μm at the maximum.
(1) After inserting the bearing member into the inner circumference of the housing (clearance fit: refer to JIS B 0401-1), fill the adhesive gap with the adhesive.
If you follow the procedure, it is difficult to fill the adhesive gap with a predetermined amount of adhesive, so
(2) An adhesive is applied to at least one of the two facing surfaces forming the adhesive gap, and then a bearing member whose inner peripheral surface is constrained by the cylindrical outer peripheral surface of the support pin is inserted into the inner circumference of the housing.
This is because there are many cases where the procedure is taken.

That is, when the above procedure (2) is followed, as the bearing member is inserted into the inner circumference of the housing, the air intervening in the internal space of the housing is compressed by the bearing member and the support pin, and the housing Internal pressure rises. At this time, as described in Patent Document 1, when the inner peripheral surface of the bearing member is restrained over the entire circumference by the cylindrical outer peripheral surface of the support pin, it is applied to at least one of the two facing surfaces forming the adhesive gap. The pre-applied adhesive is extruded to the opening side of the housing as the internal pressure of the housing increases. As a result, the amount of the adhesive to be interposed in the adhesive gap is insufficient (the region where the adhesive is appropriately interposed in the adhesive gap is reduced), and the desired fixing force cannot be secured between the housing and the bearing member.

In view of the above problems, the main object of the present invention is to enable stable mass production of an assembly in which a desired fixing force is secured between a bottomed cylindrical housing fixed by gap adhesion and a bearing member. To do.

The present invention, which was devised to achieve the above object, has a radial bearing gap on the inner peripheral surface of a bottomed tubular housing in which one end in the axial direction is open and the other end in the axial direction is closed. Of the first and second dies that are coaxially arranged so that they can move relatively close to each other and alienate from each other when fixing the bearing member forming the While contacting and supporting multiple points separated in the circumferential direction of the peripheral surface, the outer peripheral surface of the housing is restrained by the second mold, and then until the relative close movement of the first mold and the second mold is completed. The bottom space formed between the other end surface of the bearing member and the inner bottom surface of the housing due to the relative close movement of the first mold and the second mold, and one end surface of the bearing member are surfaces. It is characterized in that the space on the opening side is maintained in a state in which communication is possible through a ventilation path formed in a region of the outer peripheral surface of the support pin excluding the support portion of the bearing member.

According to the above method, both molds are relative to each other in a state where the first mold having a support pin supporting the inner peripheral surface of the bearing member and the second mold restraining the outer peripheral surface of the housing are centered. Since it moves closer to (the mold clamping operation is performed), the desired coaxiality between the inner peripheral surface of the bearing member and the outer peripheral surface of the housing even if the dimensional accuracy of the housing and / or the bearing member varies. It is possible to stably obtain an assembled product (assembly) in which the bearing is secured.

Further, according to the above method, the bearing member is formed between the other end surface of the bearing member and the inner bottom surface of the housing while the bearing member is inserted into the inner circumference of the housing due to the relative close movement of both molds. Since the space on the bottom side and the space on the opening side facing one end surface of the bearing member are always in communication with each other through the ventilation path, the internal pressure of the housing can be increased by inserting the bearing member into the inner circumference of the housing. It is prevented. Therefore, even when the bearing member is inserted into the inner circumference of the housing with the adhesive applied to at least one of the inner peripheral surface of the housing and the outer peripheral surface of the bearing member forming the adhesive gap, the adhesive accompanies the increase in the internal pressure of the housing. It is possible to avoid the external leakage of the. This makes it possible to appropriately interpose a predetermined amount of adhesive between the inner peripheral surface of the housing and the outer peripheral surface of the bearing member, so that a desired fixing force is secured between the housing and the bearing member. The assembly can be obtained stably.

It is preferable that the bearing member is contact-supported (line contact-supported) with support pins at three or more locations separated in the circumferential direction of the inner peripheral surface thereof. As a result, the support accuracy of the bearing member by the support pin can be improved, which is advantageous in manufacturing a high-precision assembly.

When the relative close movement of the first mold and the second mold is completed (when the molds of both molds are completed), if the housing is held in the axial direction by both molds, the end face of the housing (for example, It is advantageous to obtain an assembly in which the squareness between the inner bottom surface) and the inner peripheral surface of the bearing member is controlled with high precision.

From the above, according to the present invention, it is possible to stably mass-produce an assembly in which a desired fixing force (adhesive strength) and coaxiality are secured between a housing and a bearing member.

It is a figure which conceptually shows a fan motor provided with a fluid dynamic pressure bearing device. FIG. 3 is an enlarged cross-sectional view of the hydrodynamic bearing device shown in FIG. 1. It is a vertical sectional view of a bearing member. FIG. 3 is a plan view of the bearing member shown in FIG. 3 when viewed from above. It is a partial vertical sectional view in the state before mold clamping of an assembly apparatus. FIG. 5 is a cross-sectional view taken along the line XX in FIG. It is a partial vertical sectional view in a molded state of an assembly apparatus. Both the figure (a) and the figure (b) are partial cross-sectional views of the assembly apparatus according to another embodiment. It is a partial cross-sectional view of the assembly apparatus which concerns on other embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 conceptually shows a configuration example of a motor (fan motor) provided with a fluid dynamic bearing device 1. The fan motor shown in the figure includes a fluid dynamic bearing device 1, a motor base 6 constituting the stationary side of the motor, a stator coil 5 attached to the motor base 6, and a rotor 3 as a rotating member having blades. , A rotor magnet 4 attached to the rotor 3 and facing the stator coil 5 via a radial gap. The housing 7 of the fluid dynamic bearing device 1 is fixed to the inner circumference 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 in this way, 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 the shaft member 2 and the shaft member 2 are accompanied by this rotation. The rotor 3 fixed to the rotor 3 rotates integrally.

When the rotor 3 rotates, wind is sent upward or downward in the figure depending on the form of the blades provided on the rotor 3. Therefore, during the rotation of the rotor 3, a downward or upward thrust in the figure acts on the shaft member 2 of the fluid dynamic pressure bearing device 1 as a reaction force of this blowing action. A magnetic force (repulsive force) in a direction that cancels this thrust is applied between the stator coil 5 and the rotor magnet 4, and the thrust load generated by the difference between the thrust and the magnitude of the magnetic force is the fluid dynamic bearing device 1. It is supported by the thrust bearing portion T of. Further, when the rotor 3 is rotated, a radial load acts on the shaft member 2 of the fluid dynamic bearing device 1. This radial load is supported by the radial bearing portions R1 and R2 of the fluid dynamic bearing device 1.

FIG. 2 shows an enlarged cross-sectional view of the fluid dynamic bearing device 1 shown in FIG. The hydrodynamic bearing device 1 includes a bottomed tubular housing 7 in which one end in the axial direction is opened and the other end in the axial direction is closed, a bearing member 8 fixed to the inner circumference of the housing 7, and a bearing. A shaft member 2 inserted into the inner circumference of the member 8 and a sealing member 9 for sealing one end opening of the housing 7 are provided, and the internal space of the housing 7 is a lubricating oil as a lubricating fluid (dense dispersion in the figure). It is filled with (indicated by dot hatching). Hereinafter, for convenience of explanation, the side on which the seal member 9 is arranged is referred to as the upper side, and the side opposite to the axial direction thereof is referred to as the lower side, but it is not intended to limit the usage posture of the fluid dynamic bearing device 1.

The housing 7 is made of a metal material such as brass to form a bottomed cylinder having a cylindrical cylinder 71 and a disk-shaped bottom 72 integrally closing the lower end opening thereof. The housing 7 of the present embodiment integrally has a step portion 73 arranged on the inner circumference of the boundary portion between the tubular portion 71 and the bottom portion 72. Further, in the present embodiment, a thrust plate 74 formed in a disk shape made of a highly slidable resin material is placed on the upper end surface of the bottom portion 72, and the inner bottom surface 7b of the housing 7 is formed on the upper end surface of the thrust plate 74. are doing. As the housing 7, a resin material formed in a bottomed tubular shape may be used, and in this case, the thrust plate 74 is basically omitted.

The shaft member 2 is made of a metal material such as stainless steel, and its lower end surface 2b is formed on a convex spherical surface. A rotor 3 having blades (see FIG. 1) is fixed to the upper end of the shaft member 2.

The bearing member 8 is formed in a cylindrical shape with a porous body, here, a porous body of a sintered metal containing copper and iron as main components, and its internal pores are filled with lubricating oil filled in the internal space of the housing 7. It is impregnated with the same type of lubricating oil. As the bearing member 8, a material formed of a porous body other than a sintered metal such as a porous resin may be used, or a material formed of a non-porous metal material or a resin material may be used. Is also good.

On the inner peripheral surface 8a of the bearing member 8, a cylindrical radial bearing surface that forms a radial bearing gap between the radial bearing portions R1 and R2 is separated from the outer peripheral surface 2a of the opposing shaft member 2 at two upper and lower positions. Is provided. As shown in FIG. 3, dynamic pressure generating portions (radial dynamic pressure generating portions) A1 and A2 for generating a dynamic pressure action on the lubricating oil in the radial bearing gap are formed on each radial bearing surface, respectively. The radial dynamic pressure generating portions A1 and A2 in the illustrated example have a convex shape that separates a plurality of upper dynamic pressure grooves Aa1 and lower dynamic pressure grooves Aa2 and both dynamic pressure grooves Aa1 and Aa2, respectively, which are inclined in opposite directions. It has a hill and the hill has a herringbone shape as a whole. That is, the hill portion is provided between the inclined hill portion Ab provided between the adjacent dynamic pressure grooves in the circumferential direction and the upper and lower dynamic pressure grooves Aa1 and Aa2, and the annular hill portion having substantially the same diameter as the inclined hill portion Ab. It consists of Ac.

In the upper dynamic pressure generating portion A1, the axial dimension X ₁ of the upper dynamic pressure groove Aa1 is set to be larger than the axial dimension X ₂ of the lower dynamic pressure groove Aa2 (X ₁ > X ₂ ), and the lower side. In the radial dynamic pressure generating portion A2 of the above, the axial dimension of the upper dynamic pressure groove Aa1 and the lower dynamic pressure groove Aa2 is the axial dimension X of the lower dynamic pressure groove Aa2 constituting the upper radial dynamic pressure generating portion A1. It is set to be the same as ₂ . Therefore, when the shaft member 2 and the bearing member 8 rotate relative to each other, the lubricating oil interposed in the radial gap (radial bearing gap) between the outer peripheral surface 2a of the shaft member 2 and the inner peripheral surface 8a of the bearing member 8 is on the lower side. Be pushed in.

As shown in FIGS. 2 to 4, in the upper end surface 8c of the bearing member 8, the outer diameter end portion opens to the upper end outer peripheral chamfer of the bearing member 8 and the inner diameter end portion opens to the upper end inner peripheral chamfer of the bearing member 8. The radial groove 8c1 is formed. In this embodiment, radial grooves 8c1 are evenly arranged at three locations separated in the circumferential direction. Further, on the lower end surface 8b of the bearing member 8, an annular groove 8b1 arranged at a substantially central portion in the radial direction thereof, an inner diameter end portion opens into the annular groove 8b1, and an outer diameter end portion is a lower end outer peripheral chamfer of the bearing member 8. A radial groove 8b2 opened in the above is formed. Although detailed illustration is omitted, in the present embodiment, the radial grooves 8b2 are equally arranged at three locations separated in the circumferential direction, similarly to the radial groove 8c1.

On the outer peripheral surface 8d of the bearing member 8, a plurality of axial grooves 8d1 having an upper end portion opened in the upper end outer peripheral chamfer of the bearing member 8 and an lower end portion opened in the lower end outer peripheral chamfer of the bearing member 8 are separated in the circumferential direction. It is formed in (three places in the illustrated example). The axial groove 8d1 is arranged at a position different from that of the radial groove 8b2 (8c1) in the circumferential direction, and in the present embodiment, the axial groove 8d1 is located at an intermediate position between two adjacent radial grooves 8b2 (8c1). Axial groove 8d1 is arranged.

The bearing member 8 having the above configuration is fixed to the inner circumference of the housing 7 by gap adhesion in a state where the lower end surface 8b is in contact with the upper end surface of the step portion 73 of the housing 7. Therefore, the outer diameter dimension of the bearing member 8 (diameter dimension of the outer peripheral surface 8d) is set smaller than the inner diameter dimension of the housing 7 (diameter dimension of the inner peripheral surface 7a). Since the bearing member 8 is fixed to the inner circumference of the housing 7 in this embodiment, the lower end surface 8b of the bearing member 8 faces the inner bottom surface 7b of the housing 7 via the bottom space 10. The annular groove 8b1 formed on the lower end surface 8b of the bearing member 8 has a partial region on the inner diameter side open to the bottom space 10.

The procedure for fixing the housing 7 and the bearing member 8 will be described in detail later, but briefly, the bearing member 8 is fitted with a clearance fit on the inner circumference of the tubular portion 71 (see JIS B 0401-1). By solidifying the adhesive 13 (see FIG. 5) interposed in the radial gap (adhesive gap) 11 formed between the outer peripheral surface 8d of the bearing member 8 facing each other and the inner peripheral surface 7a of the housing 7. It is fixed to the inner circumference of the cylinder portion 71 of the housing 7. Therefore, the bearing member 8 is fixed to the inner circumference of the tubular portion 71 via the adhesive layer 12 formed by solidifying the adhesive 13 (see the enlarged view in FIG. 2 above). As the adhesive 13, for example, a thermosetting adhesive or an anaerobic adhesive can be used.

The seal member 9 is formed in an annular shape from a metal material or a resin material, and is fixed to the inner peripheral surface 7a of the housing 7 by an appropriate means in a state where the lower end surface 9b thereof is in contact with the upper end surface 8c of the bearing member 8. ing. The inner peripheral surface 9a of the seal member 9 is formed in a tapered surface shape whose diameter is gradually reduced downward, and the gap width is gradually reduced downward between the inner peripheral surface 9a and the outer peripheral surface 2a of the opposing shaft member 2. A wedge-shaped seal gap S is formed. The seal gap S has a buffer function of absorbing the amount of volume change due to the temperature change of the lubricating oil filled in the internal space of the housing 7, and always seals the oil level of the lubricating oil within the range of the assumed temperature change. It is held within the axial range of the gap S.

In the hydrodynamic bearing device 1 having the above configuration, when the shaft member 2 and the bearing member 8 rotate relative to each other (in the present embodiment, the shaft member 2 rotates), the inner peripheral surface 8a of the bearing member 8 is rotated at two locations above and below. A radial bearing gap is formed between the radial bearing surface provided apart from the bearing surface and the outer peripheral surface 2a of the shaft member 2 facing the radial bearing surface. Then, as the shaft member 2 rotates, the pressure of the oil film formed in the gap between both radial bearings is increased by the dynamic pressure action of the radial dynamic pressure generating portions A1 and A2. As a result, the radial bearing portions R1 and R2 that non-contactly support the shaft member 2 in the radial direction are formed at two positions separated from each other in the vertical direction. At the same time, a thrust bearing portion T that contacts and supports the shaft member 2 in the thrust direction is formed on the inner bottom surface 7b of the housing 7.

When the shaft member 2 is rotated, the outer peripheral surface 2a of the shaft member 2 and the bearing member 8 are affected by the axial dimensional difference between the upper dynamic pressure groove Aa1 and the lower dynamic pressure groove Aa2 constituting the upper radial dynamic pressure generating portion A1. Lubricating oil intervening in the radial gap (particularly the radial bearing gap of the radial bearing portion R1) between the inner peripheral surface 8a is pushed downward, and the bottom space 10 → the annular groove provided in the lower end surface 8b of the bearing member 8. Fluid passage formed by 8b1 and radial groove 8b2 → Circular space formed by the lower end outer peripheral chamfer of the bearing member 8 (and the annular groove provided at the outer diameter end of the step portion 73 of the housing 7) → Outer circumference of the bearing member 8. Fluid passage formed by the axial groove 8d1 provided on the surface 8d → An annular space formed by the upper end outer peripheral chamfer of the bearing member 8 → Fluid passage formed by the radial groove 8c1 provided on the upper end surface 8c of the bearing member 8. It circulates through a series of circulation paths, and is drawn into the radial bearing gap of the radial bearing portion R1 again. As a result, the pressure balance of the lubricating oil that fills the internal space of the housing 7 is maintained, so that bubbles are generated due to the generation of local negative pressure, and the lubricating oil is leaked to the outside or vibration is generated due to the generation of bubbles. It is possible to avoid the occurrence of the problem.

In the hydrodynamic bearing device 1 described above, for example, the bearing member 8 and the seal member 9 are assembled to the housing 7, the shaft member 2 is inserted into the inner circumference of the bearing member 8, and then the shaft member 2 is inserted into the internal space of the housing 7. It is completed by taking steps such as filling the bearing member 8 with lubricating oil including the internal pores. Since the present invention has a main feature in the method of assembling the housing 7 and the bearing member 8 (the method of manufacturing the assembly formed by assembling the housing 7 and the bearing member 8), the above is described below with reference to FIGS. 5 to 9. The assembly manufacturing process will be described in detail.

5 to 7 show an example of the assembly device 20 used in the assembly manufacturing process. 5 is a partial vertical cross-sectional view of the assembly device 20 in a state before molding, FIG. 6 is a cross-sectional view taken along the line XX of FIG. 5, and FIG. 7 is a state in which the assembly device 20 is molded. It is a partial vertical sectional view. The assembly device 20 shown in FIGS. 5 to 7 is arranged below the first mold 21 having a support pin 24 for supporting the inner peripheral surface 8a of the bearing member 8 and holding the housing 7. The second mold 22 and the third mold 23 arranged on the outer diameter side of the first mold 21 are provided. In the present embodiment, the second die 22 and the third die 23 are fixed to a surface plate (not shown) to form a stationary side, and the first die 21 is attached to an elevating member of a press device (not shown). It constitutes the movable side.

The first mold 21 has a small diameter portion 25 having a relatively small outer diameter dimension and a large diameter portion 26 having a relatively large outer diameter dimension, and the support pin 24 protrudes to the lower side of the small diameter portion 25. It is provided integrally with the small diameter portion 25 so as to be provided. The first mold 21 has a hole portion 27 extending in the vertical direction along the central axis thereof, and the lower end of the hole portion 27 is open to the lower end surface of the support pin 24. Although not shown, an intake pipe extending from the intake device is connected to the upper end of the hole 27.

The support pin 24 is formed in a non-circular cross section, and in the present embodiment, the support pin 24 is formed in a triangular cross section (regular triangular shape) as shown in FIG. Therefore, when the bearing member 8 is fitted to the outer periphery of the support pin 24, three points separated in the circumferential direction of the inner peripheral surface 8a of the bearing member 8 are contacted (line contacted) and supported. That is, the support pin 24 has support portions 24a for contacting (line contacting) the inner peripheral surface 8a of the bearing member 8 at three locations separated in the circumferential direction of the outer peripheral surface, and connecting the support portions 24a. The diameter of the circular orbit formed is slightly larger (for example, less than 5 μm) than the diameter of the inner peripheral surface 8a of the bearing member 8. In addition, in order to prevent defects such as scratches from occurring on the inner peripheral surface 8a of the bearing member 8 as a result of fitting the bearing member 8 to the outer periphery of the support pin 24, each support portion 24a ( The contact portion of the bearing member 8 with the inner peripheral surface 8a) is formed in a rounded shape of about 0.1 mm (see an enlarged view in FIG. 6).

The second mold 22 has a cylindrical inner peripheral surface 22a capable of restraining (lightly press-fitting) the cylindrical outer peripheral surface 7c of the housing 7, and an inner bottom surface 22b capable of contacting and supporting the outer bottom surface 7d of the housing 7 from below. The upper end surface 22c is arranged coaxially with the first mold 21 and the third mold 23 in a state where the upper end surface 22c is in contact with the lower end surface of the small diameter cylinder portion 23a of the third mold 23. The separation distance between the inner bottom surface 22b of the second mold 22 and the upper end surface 22c is set to be smaller than the axial dimension of the housing 7 held by the second mold 22. Therefore, as shown in FIG. 5, when the housing 7 is held by the second mold 22, the upper end surface 7e of the tubular portion 71 of the housing 7 is located above the upper end surface 22c of the second mold 22. Of the second mold 22 having the above configuration, the dimensional accuracy of the inner peripheral surface 22a which is the restraining surface for restraining the outer peripheral surface 7c of the housing 7 is the accuracy of assembling the bearing member 8 to the housing 7 (the outer peripheral surface of the housing 7). The coaxiality between 7c and the inner peripheral surface 8a of the bearing member 8) is greatly affected. Therefore, the dimensional accuracy of the inner peripheral surface 22a is finished with high accuracy so as to satisfy the coaxiality (for example, 3 μm or less) required between the outer peripheral surface 7c of the housing 7 and the inner peripheral surface 8a of the bearing member 8. Has been done.

The third mold 23 integrally includes a small diameter cylinder portion 23a having a relatively small inner diameter dimension and a large diameter cylinder portion 23b having a relatively large inner diameter dimension and the second mold 22 fitted to the inner circumference. Have. The inner peripheral surface 23a1 of the small-diameter cylinder portion 23a functions as a guide surface for guiding the outer peripheral surface 26a of the large-diameter portion 26 of the first mold 21 when the first mold 21 moves up and down, so that the dimensional accuracy thereof is correct. This affects the operating accuracy of the first mold 21 and, by extension, the assembly accuracy of the bearing member 8 with respect to the housing 7. Therefore, the dimensional accuracy of the inner peripheral surface 23a1 of the small-diameter tubular portion 23a is finished with high accuracy so as to satisfy the coaxiality required between the outer peripheral surface 7c of the housing 7 and the inner peripheral surface 8a of the bearing member 8. Has been done.

In the assembly device 20 having the above configuration, as shown in FIG. 5, the bearing member 8 is fitted to the outer periphery of the support pin 24 of the first mold 21 to support the bearing member 8 and the second mold 22. The housing 7 is fitted to the inner circumference of the housing 7 and the outer peripheral surface 7c of the housing 7 is restrained by the inner peripheral surface 22a of the second mold 22. The inner peripheral surface 7a of the housing 7 and the outer peripheral surface 8d of the bearing member 8 forming the bonding gap 11 (see FIG. 1) before fitting to the molds 21 and 22 or after fitting to the molds 21 and 22. An adhesive 13 for adhesively fixing the housing 7 and the bearing member 8 is applied to at least one of them. In the present embodiment, the adhesive 13 is applied to a predetermined position in the axial direction of the inner peripheral surface 7a of the housing 7 over the entire circumference.

The bearing member 8 has an upper end surface 8c and a lower end surface of the small diameter portion 25 of the first mold 21 facing the upper end surface 8c until the mold tightening of both molds 21 and 22 accompanying the downward movement of the first mold 21 is completed. It is fitted to the outer periphery of the support pin 24 so that the non-contact state with the 25a is maintained. Here, the separation distance between the lower end surface 8b of the bearing member 8 and the lower end surface 25a of the small diameter portion 25 is set to be equal to the separation distance between the upper end surface 7e of the tubular portion 71 of the housing 7 and the upper end surface of the step portion 73. The bearing member 8 is fitted to the outer periphery of the support pin 24.

As described with reference to FIG. 6, since the support pin 24 of the present embodiment is formed in a regular triangular cross section, the bearing member 8 fitted to the outer periphery of the support pin 24 has an inner peripheral surface 8a. Three points separated in the circumferential direction are supported by line contact. Since the bearing member 8 is supported in this embodiment, the area of the outer peripheral surface of the support pin 24 excluding the support portion 24a that supports the bearing member 8 in line contact (the connection surface 24b that connects the support portions 24a). As shown in FIG. 6, between the inner peripheral surface 8a of the bearing member 8 and the space formed by the lower end surface 8b of the bearing member 8 (bottom side space 10: see FIG. 2) and the upper end surface of the bearing member 8. A ventilation path 30 that allows air to flow in and out of the space (opening side space) formed by 8c is formed.

After setting the bearing member 8 and the housing 7 in the assembling device 20 as described above, the molds 21 and 22 are relatively close to each other (the first mold 21 is moved downward), and the molds are fastened. .. Although detailed illustration is omitted, when the first mold 21 moves downward to some extent, the outer peripheral surface 8d of the bearing member 8 comes into contact with the adhesive 13 applied to the inner peripheral surface 7a of the housing 7, and thereafter, the second die. As the mold 21 moves downward, the adhesive 13 is filled in the adhesive gap 11 (see FIG. 1) between the inner peripheral surface 7a of the housing 7 and the outer peripheral surface 8d of the bearing member 8. Then, as shown in FIG. 7, when the lower end surface 8b of the bearing member 8 comes into contact with the upper end surface of the step portion 73 of the housing 7, the downward movement of the first mold 21 is stopped. As described above, the bearing member 8 has a distance between the lower end surface 8b and the lower end surface 25a of the small diameter portion 25 of the first mold 21 above the upper end surface 7e and the step portion 73 of the tubular portion 71 of the housing 7. The bearing member 8 is fitted on the outer periphery of the support pin 24 so as to be equal to the distance from the end face. Therefore, when the lower end surface 8b of the bearing member 8 comes into contact with the upper end surface of the step portion 73 of the housing 7, the upper end surface 7e of the tubular portion 71 of the housing 7 hits the lower end surface 25a of the small diameter portion 25 of the first mold 21. Contact. As a result, the housing 7 is in a state of being sandwiched between the first mold 21 and the second mold 22 in the axial direction.

After the downward movement of the first mold 21 is stopped, the adhesive 13 filled in the adhesive gap 11 is solidified to form the adhesive layer 12 (see FIG. 2). As a result, an assembly in which the bearing member 8 is fixed to the inner circumference of the housing 7 by gap adhesion can be obtained in a state where the bearing member 8 is properly positioned in the axial direction with respect to the housing 7. After being taken out from the assembly device 20, this assembly is transferred to a subsequent process (for example, an assembly process of the sealing member 9).

As described above, in the present embodiment, of the first mold 21 and the second mold 22 coaxially arranged so as to be relatively close to each other and detachable from each other, the support pin 24 provided in the first mold 21 is provided. The inner peripheral surface 8a of the bearing member 8 is contact-supported, and the bearing member 8 is gap-bonded to the inner peripheral surface of the housing 7 in a state where the outer peripheral surface 7c of the housing 7 is restrained by the second mold 22. By doing so, even if the dimensional accuracy of the inner peripheral surface 7a of the housing 7 and / or the outer peripheral surface 8d of the bearing member 8 varies, the inner peripheral surface 8a of the bearing member 8 and the outer peripheral surface 7c of the housing 7 It is possible to stably obtain an assembly in which a desired coaxiality (for example, about 3 μm) is secured between the two.

Further, as described with reference to FIG. 6, when the inner peripheral surface 8a of the bearing member 8 is contact-supported by the support pin 24 of the first mold 21, the bearing member 8 is used among the outer peripheral surfaces of the support pin 24. A space formed by the lower end surface 8b of the bearing member 8 between the region excluding the support portion 24a supported by line contact (the connection surface 24b connecting the support portions 24a) and the inner peripheral surface 8a of the bearing member 8. An air passage 30 that allows air to flow in and out of the space formed by the upper end surface 8c of the bearing member 8 is formed, and the air passage 30 moves downward of the first mold 21 (both molds 21 and 22). The bearing member 8 continues to exist until the mold clamping is completed, that is, until the insertion of the bearing member 8 into the inner circumference of the housing 7 is completed. By doing so, the bottom side space formed between the lower end surface 8b of the bearing member 8 (and the lower end surface of the support pin 24) and the inner bottom surface 7b of the housing 7 as the first mold 21 moves downward. Since the space 10 and the opening side space formed by the upper end surface 8c of the bearing member 8 are maintained in a state in which they can communicate with each other through the ventilation passage 30, the bearing member 8 is inserted into the inner circumference of the housing 7. The increase in internal pressure of the housing 7 is prevented as much as possible.

Therefore, the housing 7 is coated with the adhesive 13 on at least one of the inner peripheral surface 7a of the housing 7 forming the bonding gap 11 and the outer peripheral surface 8d of the bearing member 8 (in the present embodiment, the inner peripheral surface 7a of the housing 7). Even when the bearing member 8 is inserted into the inner circumference of the housing 7, the adhesive 13 is pushed out to the opening side of the housing 7 as the internal pressure of the housing 7 rises, and as a result, the amount of the adhesive 13 to be interposed in the bonding gap 11 is increased. It is possible to avoid the occurrence of problems such as shortage. As a result, a predetermined amount of the adhesive 13 can be appropriately interposed in the adhesive gap 11 formed between the inner peripheral surface 7a of the housing 7 and the outer peripheral surface 8d of the bearing member 8, so that the housing 7 and the housing 7 can be appropriately interposed. It is possible to stably obtain an assembly in which a desired fixing force is secured between the bearing member 8 and the bearing member 8.

Further, in the present embodiment, when the molds of the first mold 21 and the second mold 22 are completed, the housing 7 is sandwiched in the axial direction by both molds 21 and 22, and the bonding gap 11 is filled in that state. The adhesive 13 is solidified. In this case, the lower end surface 25a of the small diameter tubular portion 25 of the first mold 21 which is the restraining surface for restraining the upper end surface 7e of the tubular portion 71 of the housing 7, and the constraining surface which is the restraining surface for restraining the outer bottom surface 7d of the housing 7. If the parallelism between the inner bottom surface 22b of the 2 mold 22 and the squareness of the inner bottom surface 22b of the second mold 22 with respect to the first mold 21 are controlled to predetermined values, the inner bottom surface 7b of the housing 7 can be controlled. It is possible to obtain an assembly in which the squareness between the bearing member 8 and the inner peripheral surface 8a of the bearing member 8 is controlled with high accuracy.

In this embodiment, since the adhesive 13 is applied over the entire circumference of the inner peripheral surface 7a of the housing 7, the adhesive 13 is a bearing member in the adhesive gap 11 unless any measures are taken. The forming region of the axial groove 8d1 provided on the outer peripheral surface 8d of 8 is also filled. If the adhesive 13 is solidified in this state, it becomes difficult to flow and circulate the lubricating oil inside the housing 7 while the shaft member 2 is rotating. Therefore, in the present embodiment, the intake device connected to the hole 27 of the first mold 21 is driven during the downward movement of the first mold 21 or after the downward movement of the first mold 21 is completed, and the bonding gap is formed. The adhesive 13 filled in the forming region of the axial groove 8d1 of 11 is sucked through the hole 27, and then the adhesive 13 is solidified. As a result, the above-mentioned problem is prevented from occurring as much as possible.

From the above, according to the present invention, it is possible to stably mass-produce an assembly in which a desired fixing force (adhesive strength) and fixing accuracy are ensured between the housing 7 and the bearing member 8. Therefore, the above-mentioned fluid dynamic bearing device 1 having this assembly as a component is highly reliable so that the desired bearing performance can be stably exhibited for a long period of time.

The method for manufacturing the fluid dynamic bearing device 1 according to the embodiment of the present invention (method for manufacturing an assembly in which the bearing member 8 is gap-bonded to the inner circumference of the housing 7) has been described above. Can make various changes without departing from the gist of the present invention.

For example, in the embodiment described above, as the support pins 24 for supporting the inner peripheral surface 8a of the bearing member 8, those capable of line-contact support at three locations separated in the circumferential direction of the inner peripheral surface 8a are used. However, as the support pin 24, as shown in FIG. 8 (a), four points separated in the circumferential direction of the inner peripheral surface 8a can be line-contacted and supported, or as shown in FIG. 8 (b), the inner It is also possible to use a peripheral surface 8a capable of supporting line contact at five locations separated in the circumferential direction. The effects of the present invention can be similarly enjoyed even when a support pin 24 capable of linearly contacting and supporting two points separated in the circumferential direction of the inner peripheral surface 8a of the bearing member 8 is used, but the support accuracy of the bearing member 8 is improved. This is disadvantageous as compared with the case of using a support pin 24 capable of linearly contacting and supporting three or more points on the inner peripheral surface 8a. Therefore, it is preferable that the inner peripheral surface 8a of the bearing member 8 is contact-supported at three or more locations separated in the circumferential direction.

Further, in the embodiment described above, the support pins 24 capable of line-contact support at a plurality of locations separated in the circumferential direction of the inner peripheral surface 8a of the bearing member 8 are used, but the support pins 24 are bearings. A member that can support surface contact at a plurality of locations separated in the circumferential direction of the inner peripheral surface 8a of the member 8 may be used. FIG. 9 shows an example thereof, in which a bearing is provided with a support pin 24 provided with a support portion (support surface) 24a capable of surface contact supporting the inner peripheral surface 8a of the bearing member 8 at three locations separated in the circumferential direction of the outer peripheral surface. It is a cross-sectional view when the member 8 is supported.

Further, in the embodiment described above, the first mold 21 is arranged relatively on the upper side, the second mold 22 is arranged on the relatively lower side, and the first mold 21 constitutes the movable side. However, on the contrary, the first mold 21 is arranged relatively on the lower side and the second mold 22 is arranged on the relatively upper side, and the second mold 21 is arranged. The present invention can be similarly applied to the case where the assembling device 20 constituting the movable side is used, or when the assembling device 20 in which both the first mold 21 and the second mold 22 move up and down is used.

Further, in the embodiment described above, the adhesive 13 is previously applied to at least one of the inner peripheral surface 7a of the housing 7 forming the bonding gap 11 and the outer peripheral surface 8d of the bearing member 8, and then the first mold 21 is used. And the second mold 22 are moved relatively close to each other (the first mold 21 is moved downward) to fill the adhesive gap 11 with the adhesive 13, but the adhesive 13 is inside the housing 7. After the bearing member 8 is squeezed around the circumference, it may be supplied to the end of the bonding gap 11 formed between the two on the opening side of the housing 7. When such a procedure is performed, as the bearing member 8 is inserted into the inner circumference of the housing 7, it is applied in advance to at least one of the inner peripheral surface 7a of the housing 7 and the outer peripheral surface 8d of the bearing member 8. The above-mentioned problem that the adhesive 13 is pushed out to the opening side of the housing 7 does not occur, but the increase in the internal pressure of the housing 7 due to the insertion of the bearing member 8 is prevented as much as possible, so that the adhesive gap 11 is used to prevent the adhesive 13 from increasing. There is an advantage that the supply failure of the adhesive 13 due to the compressed air discharged to the outside of the bearing can be prevented as much as possible.

When the above procedure is performed, the adhesive 13 is formed in a desired circumferential region (for example, a circumferential region avoiding the formation region of the axial groove 8d1 provided on the outer peripheral surface 8d of the bearing sleeve 8) in the adhesive gap 11. There is an advantage that it can be filled with high accuracy. However, in this case, after the adhesive 13 is supplied in the above embodiment, the intake device connected to the hole 27 of the first mold 21 is driven and supplied to the end of the bonding gap 11 on the opening side of the housing 7. It is preferable to pull the adhesive 13 to the bottom side of the housing 7. Thereby, the adhesive layer 12 (see FIG. 2) having a predetermined axial dimension can be formed, and thus an assembly in which the desired fixing force is secured between the housing 7 and the bearing member 8 can be obtained. can.

In short, if the present invention is adopted, the adhesive 13 is applied to at least one of the two facing surfaces 7a and 8d forming the adhesive gap 11 before the bearing member 8 is squeezed on the inner circumference of the housing 7. In any case where the bearing member 8 is squeezed into the inner circumference of the housing 7 and then the adhesive 13 is supplied to the adhesive gap 11, a predetermined amount of the adhesive 13 may be interposed in the adhesive gap 11. It will be easy.

Further, the fluid dynamic pressure bearing device 1 described with reference to FIGS. 1 to 4 is merely an example of a fluid dynamic pressure bearing device manufactured by applying the manufacturing method according to the present invention, and has a bottomed tubular shape. The present invention can be preferably applied in the manufacturing process of a fluid dynamic bearing device provided with an assembly in which the bearing member 8 is fixed to the inner circumference of the housing 7 by gap adhesion.

1 Fluid dynamic bearing device 2 Shaft member 3 Lower end surface 7 Housing 7a Inner peripheral surface 8 Bearing member 8d Outer peripheral surface 10 Bottom side space 11 Adhesive gap 12 Adhesive layer 13 Adhesive 20 Assembly device 21 1st mold 22 2nd metal Mold 24 Support pin 24a Support part 24b Connection surface 30 Ventilation path 71 Cylinder part 72 Bottom part

Claims (3)

When fixing a bearing member that forms a radial bearing gap on the inner peripheral surface to the inner circumference of a bottomed tubular housing with one end in the axial direction open and the other end in the axial direction closed by gap adhesion.
Of the first and second dies coaxially arranged so that they can move relatively close to each other and detached from each other, a support pin provided on the first die contacts and supports a plurality of locations separated from each other on the inner peripheral surface of the bearing member in the circumferential direction. At the same time, restrain the outer peripheral surface of the housing with the second mold,
After that, until the relative close movement of the first mold and the second mold is completed, the other end surface of the bearing member and the housing are subjected to the relative close movement of the first mold and the second mold. A ventilation path formed by forming a bottom space formed between the inner bottom surface and an opening side space facing one end surface of the bearing member in a region of the outer peripheral surface of the support pin excluding the support portion of the bearing member. A method for manufacturing a hydrodynamic bearing device, which comprises maintaining a state in which communication is possible through the bearing. The method for manufacturing a fluid dynamic bearing device according to claim 1, wherein three or more locations separated in the circumferential direction of the inner peripheral surface of the bearing member are contact-supported by support pins. The fluid dynamic bearing device according to claim 1 or 2, wherein the housing is axially sandwiched between the first mold and the second mold when the relative close movement between the first mold and the second mold is completed. Manufacturing method.

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