JP2007170578A - Member for dynamic pressure bearing, mould for moulding same, method for manufacturing same, and dynamic pressure bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a member for a dynamic pressure bearing preventing a rotary shaft from being pulled out and a radial dynamic pressure groove from being damaged, a mould for moulding the same, a method for manufacturing the same, and the dynamic pressure bearing. <P>SOLUTION: This member 30A for the dynamic pressure bearing is provided with a predetermined length, has a bearing hole 51 having a round inner section in which a rotary shaft 31 is inserted opened thereon, consists of a bottomed 52 resin tube part 50 of which one end opens as a rotary shaft insertion opening 51a, has predetermined shape radial dynamic pressure grooves Ra, Rb formed on an inner circumference surface 53 of a bearing hole 51 of the tube part 50, has a thrust bearing part S formed on a bottom part 50, and has a retaining washer engagement groove 57 integrally formed above a part near the thrust bearing part S. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydrodynamic bearing member suitable for a hydrodynamic bearing, in particular, a molding die thereof, in which a hydrodynamic groove through which a rotating shaft does not come off is formed as a radial bearing surface on a cylindrical inner peripheral surface, The present invention relates to an improved manufacturing method and hydrodynamic bearing.

  First, referring to FIGS. 21 to 25, the structure of various conventional bearing units that support the motor of the prior art as an example and the rotating shaft thereof and the structure of the dynamic pressure bearing member will be described.

  21 is a cross-sectional view of an example of a small motor used in a small electronic device, FIG. 22 is a cross-sectional side view of a bearing unit of the first embodiment that can be used in the motor shown in FIG. 21, and FIG. FIG. 24 is a cross-sectional perspective view of a dynamic pressure bearing member incorporated in the bearing unit shown in FIG. 24, FIG. 24 is a cross-sectional side view of a second type bearing unit that can be used in the motor shown in FIG. 1 shows a conventional hydrodynamic bearing member that can be incorporated into a bearing unit of the embodiment, wherein FIG. A is a sectional side view thereof, FIG. B is a partially enlarged view of FIG. A, and FIG. The core pin of the 1st example used when carrying out injection molding of the member for bearings is shown, The figure A is the side view, The figure B is the expanded sectional view of the principal part, FIG. 27 is the core pin shown in FIG. Example of injection mold for injection molding using 28 is a cross-sectional view of the main part, and FIG. 28 is a partial injection mold and dynamic pressure shown in FIG. 27 for explaining a method of releasing the dynamic pressure bearing member formed by the injection mold shown in FIG. 29 is a sectional view of a bearing member, FIG. 29 is an enlarged sectional view of a main part of a core pin of a third example of the prior art, and FIG. 30 is a diagram of a second example of a hydrodynamic bearing member injection-molded using the core pin of FIG. It is an expanded sectional view of the principal part.

  First, the configuration and structure of the motor will be described with reference to FIG.

  The motor in the form shown in the figure is a motor, particularly a motor with a heat dissipation device, which is suitable for being incorporated in an electronic device, particularly a small electronic device, which performs various kinds of information processing, recording / reproduction, etc. of a computer, particularly a notebook computer.

  A heat dissipation device is provided inside an electronic device such as a notebook computer. The heat radiating device includes a metal base, a motor 1 attached to the base, a fan 3 that rotates by the motor 1, a fan case 4 that houses the fan 3, and a heat sink (not shown). ing. The motor 1 rotationally drives such a heat radiating fan 3.

  As shown in FIG. 21, the motor 1 includes a rotor 11 and a stator 12.

  The stator 12 is integrally provided on the upper surface plate 4 a side of the fan case 4 that houses the fan 3 that is rotated by the motor 1 together with the motor 1. The stator 12 includes a stator yoke 13, a bearing unit 30, a coil 14, and a core 15 around which the coil 14 is wound. The stator yoke 13 may be formed integrally with the upper surface portion 4a of the fan case 4, that is, may be formed by a part of the fan case 4, or may be formed separately. The stator yoke 13 is made of, for example, iron. The bearing unit 30 is fixed by press-fitting or bonding into a cylindrical holder 16 formed at the center of the stator yoke 13, and further by pressing and bonding.

  The holder 16 into which the bearing unit 30 is press-fitted is formed in a cylindrical shape integrally with the stator yoke 13. As shown in FIG. 21, a core 15 around which a coil 14 to which a drive current is supplied is attached is attached to the outer peripheral portion of the holder 16 formed integrally with the stator yoke 13.

  The rotor 11 that constitutes the motor 1 together with the stator 12 is attached to a rotating shaft 31 that is rotatably supported by the bearing unit 30, and rotates integrally with the rotating shaft 31. The rotor 11 includes a rotor yoke 17 and a fan 3 including a plurality of blades 19 that rotate integrally with the rotor yoke 17. The blade 19 of the fan 3 is formed integrally with the rotor yoke 17 by outsert molding on the outer peripheral surface of the rotor yoke 17. The rotary shaft 31 is supported by a dynamic pressure bearing 32.

  A ring-shaped rotor magnet 20 is provided on the inner peripheral surface of the cylindrical portion 17 a of the rotor yoke 17 so as to face the coil 14 of the stator 12. The magnet 20 is a plastic magnet in which S and N poles are alternately magnetized in the circumferential direction, and is fixed to the inner peripheral surface of the rotor yoke 17 with an adhesive.

  The rotor yoke 17 is rotated by press-fitting a boss portion 21 provided with a through hole 21a provided in the central portion of the flat plate portion 17b into a mounting portion 31d provided on the distal end side of the rotating shaft 31 supported by the bearing unit 30. The shaft 31 and the shaft 31 are rotatably attached.

  In the motor 1 having the above-described configuration, when a drive current is supplied to the coil 14 on the stator 12 side by a predetermined energization pattern from a drive circuit unit provided outside the motor 1, the magnetic field generated in the coil 14 and the rotor The rotor 11 rotates integrally with the rotating shaft 31 by the action of the magnetic field from the 11-side rotor magnet 20. As the rotor 11 rotates, the fan 3 having a plurality of blades 19 attached to the rotor 11 also rotates integrally with the rotor 11. As the fan 3 rotates, air outside the apparatus is sucked through an opening provided in the housing constituting the computer, and further, the air is circulated through the housing and is passed through the heat sink provided in the housing through the through-hole. As a result, the heat generated from the heating element is radiated to the outside of the computer main body, and the computer main body is cooled.

  Next, the bearing unit used for the motor 1 will be described with reference to FIGS. 22 and 24.

  In FIG. 22, reference numeral 30C indicates the bearing unit of the first form. The bearing unit 30C includes a rotating shaft 31B, a dynamic pressure bearing member 32 that supports the outer periphery thereof, a case 33, a lid 34, and a thrust bearing 35 that supports the lower end of the rotating shaft 31B.

  The rotary shaft 31B has a bearing support portion 31a at the lower end, a shaft main body 31b at the intermediate portion, a mounting portion 31d at the upper end, and a tapered portion 31c provided between the shaft main body 31b and the mounting portion 31d. It has a structure that can be divided functionally. The bearing support portion 31a is a portion that is supported by the thrust bearing 35, the shaft body 31b is a portion that is supported by the dynamic pressure bearing member 32, and the attachment portion 31d is a portion that attaches the rotor 11 and the like of the motor 1, The tapered portion 31c is a portion having a function of preventing leakage of the lubricating oil L filled in the bearing unit 30C in cooperation with the shaft insertion hole 34a of the lid 34.

  The thrust bearing means of the bearing unit 30C is a pivot type bearing, and the bearing support portion 31a at the lower end of the rotary shaft 31B has a spherical shape and is supported by a flat thrust bearing 35 in a point contact state.

  As shown in FIG. 23, the dynamic pressure bearing member 32 is a cylindrical part whose axial length is substantially the same as the axial length of the shaft body 31b of the rotary shaft 31B. The inner diameter is slightly larger than the diameter of the main body 31b. Two V-shaped dynamic pressure continuous grooves Ra and Rb are formed in parallel at a predetermined interval on the entire circumference of the inner peripheral surface, and the shaft main body 31b of the rotating shaft 31B is rotatably supported. To do. As a material of the fluid dynamic bearing member 23, a metal such as sintered metal, brass, stainless steel or a resin is used.

  The metal case 33 is a container having a bottom at the bottom and an opening at the top, and covers the outer shell of the bearing unit 30C.

  The thrust bearing 35 is a member that pivotally receives the bearing support portion 31a of the rotating shaft 31B, and is disposed inside the bottom surface of the case 33.

  The lid 34 is formed with a shaft insertion hole 34a through which the rotary shaft 31B can be inserted at the center thereof, and is a disk-shaped member having a diameter that can be fitted into the opening 33a at the upper end of the case 33. The bearing unit 30 </ b> C is sealed with a sealing portion 36 by fitting into the portion 33 a, and joining the joint portion 37 between the inner peripheral surface of the upper end of the case 33 and the outer peripheral surface of the lid 34 by bonding or brazing. The bearing unit 30C is filled with lubricating oil L.

  However, this bearing unit 30C not only has a large number of components and requires a lot of assembly work, but also when the electronic device incorporating the motor 1 using the bearing unit 30C is dropped, for example, the rotating shaft There is a problem that 31B is easily removed.

  In order to solve such a problem, a bearing unit 30D of the second form as shown in FIG. 24 has been proposed. In addition, the same code | symbol is attached | subjected to the same component as the bearing unit 30C, and those description is abbreviate | omitted.

  The bearing unit 30D includes a rotating shaft 31C, a dynamic pressure bearing member 32 that is a radial bearing that supports the rotating shaft 31C, and a passage forming member 38 formed outside the dynamic pressure bearing member 32. The housing 39 accommodates the passage forming member 38, a lid 40, a communication passage 41 formed between the passage forming member 38 and the fluid dynamic bearing member 32, and the like.

  In this bearing unit 30D, the passage forming member 38 does not cover only the communication passage 41 of the fluid dynamic bearing member 32, but covers the entire circumference of the fluid dynamic bearing member 32. The member 38 is configured so as to completely cover the dynamic pressure bearing member 32 except for the shaft release end 30a side.

  The passage forming member 38 is cup-shaped and has a cylindrical structure capable of covering the entire outer periphery of the fluid dynamic bearing member 32, and has a plurality of groove-shaped communication passages 41 formed on the inner surface. The dimensions are such that the gaps of these grooves can be secured. The bottom portion is a thrust bearing 38a, and the center portion of the bottom portion is a space 36 that can accommodate a flexible retaining washer W into which the rotary shaft 31C is inserted and expanded, and a bearing that is a lower end portion of the rotary shaft 31C. A space 37 that can accommodate the support portion 31a is formed concentrically. These spaces 36 and 37 also communicate with the communication passage 41 and are thrust spaces in which the lubricating oil L can circulate. Further, an engaging claw 38b is formed inward over the entire periphery of the upper opening.

  The retaining washer W is made of a flexible material such as a nylon resin that is inserted and pushed by inserting the rotary shaft 31C into the center.

  In assembling the bearing unit 30D, a retaining washer W is disposed in advance in the space 37 of the passage forming member 38, and the dynamic pressure bearing member 32 is fitted therein with the thrust bearing side end face 32b side down. The lid 40 is fitted from above the passage forming member 38, and is engaged and fixed by the engaging claw 39 so as to be in close contact with the shaft release side end surface 32a of the dynamic pressure bearing member 32.

  In this assembled state, a mold is used to seal the resin over the outer surface of the passage forming member 38 and the upper surface of the material lid 40 excluding the shaft insertion hole. Then, the resin housing 39 can be covered from the entire outer surface of the passage forming member 38 to the upper surface of the lid 40.

  After that, if the rotary shaft 31C is inserted and pushed into the shaft insertion hole of the lid 40, the central through hole of the dynamic pressure bearing member 32, and the central portion of the retaining washer W, the main bearing unit 30D having the structure shown in FIG. Is obtained.

  Accordingly, the rotating shaft 31C of the bearing unit 30D has a structure in which the retaining washer W is interposed between the lower end portion thereof and the lower end surface 32b of the dynamic pressure bearing member 32. It does not come off as described above. However, this bearing unit 30D also has a large number of parts, and there is a problem that the parts that form the radial bearing portions (dynamic pressure continuous grooves Ra and Rb) and the thrust bearing 38a are separate.

  Therefore, as shown in FIG. 25, the radial / thrust integrated type bearing unit 30E made of a radial / thrust resin, in which the radial bearing portion R and the thrust bearing S are formed in the same dynamic pressure bearing member. Is also disclosed in [Patent Document 1].

  The dynamic pressure bearing member 30E is integrally formed by injection molding of a resin. The cylindrical portion 50 has a bearing hole 51 with a circular cross section and a bottomed 52, and has an inner circumference. In the inner circumferential direction of the surface 53, the V-shaped dynamic pressure grooves (concave portions) 54 and the dynamic pressure groove land portions (convex portions) 55 are alternately arranged at a predetermined pitch and the two-stage dynamic pressure continuous grooves Ra and Rb are long. A radial bearing portion R is formed in parallel with a predetermined interval in the axial direction, and a thrust bearing portion S is formed in the central portion of the bottom portion 52 following the radial bearing portion R. A flange portion 56 is integrally formed on the outer peripheral portion of the bottom portion 52, and this also serves as a member attached to the electronic device.

  Such a dynamic pressure bearing member 30E is injection molded using the core pin 60 shown in FIG. 26 and the injection mold 70 shown in FIG.

  As shown in FIG. 26, the core pin 60 has a V-shaped pin groove Mr and a land portion L continuously on the outer peripheral surface 61 at a predetermined pitch and at a predetermined interval in the major axis direction. In parallel, a radial dynamic pressure bearing forming portion 62 composed of two stages of dynamic pressure groove forming portions 62 a and 62 b is formed, and an end face at the tip thereof is a thrust bearing forming portion 63.

  As shown in the enlarged view 26B, the edge E of the pin groove Mr of the core pin 60 is processed into a substantially R shape. Thus, by processing the edge portion E of the pin groove Mr into a substantially R shape, the release pressure when releasing the dynamic pressure bearing member 30E (FIG. 25), which is an injection molded product, from the mold during injection molding. Therefore, it can be formed with high accuracy without deformation of the dynamic pressure groove 54 of the dynamic pressure bearing member 30E and without scratching the inner peripheral surface 53 including the dynamic pressure groove 54. Further, the mold can be released smoothly, and the portion directly pressed by the ejector pin 94 (FIG. 27) or the like (the flange portion 56 in the case of the dynamic pressure bearing member 30E) is not deformed by an excessive pressing force. .

  Next, an injection mold for injection molding the dynamic pressure bearing member 30E is also described in [Patent Document 1]. The prior art injection mold is shown in FIG. 27 and the prior art method for producing a member for a hydrodynamic bearing will be described with reference to FIG.

  This injection mold 70 is a pinpoint gate type three-plate mold, and is configured by incorporating molds on a fixed side 80 and a movable side 90 and a core pin 60.

  The fixed side 80 includes a spool bush 81 having a spool 81a, a fixed side mounting plate 83 to which a runner lock pin 82 is mounted, a runner stripper plate 84, a fixed side mold 85, a fixed side mold holder 86, and the like. The side mold 85 is formed with a runner 85a, a gate 85b, and a planar parting surface 85c. In addition, you may form the cavity which can shape | mold a part of bottom part 52 in which the thrust bearing part S of a dynamic pressure bearing is formed in the parting surface 85c.

  The movable side 90 includes a movable mold 91, a core pin 60, a movable mold holder 93, an ejector pin 94, a movable mold mounting plate 95, and the like.

  The movable mold 91 has a flat parting surface 91a that can be in close contact with the parting surface 85c of the fixed mold 85, and a through hole 91b through which the core pin 60 can be inserted into the center of the cavity 92 of the movable mold 91. However, through holes 91c (only one place is shown in FIG. 27) through which the ejector pins 94 are inserted are opened at a plurality of locations in the vicinity of the through hole 91b, and dynamic pressure is applied to the parting surface 91a. A flange portion cavity 92a for forming the flange portion 56 of the bearing member 30E has a cylindrical portion cavity 92b for forming the cylindrical portion 50 of the hydrodynamic bearing member 30E on the circumferential surface of the through hole 91b on the parting surface 91a side. Is formed. The movable mold 91 is also held by a movable mold holder 93. That is, the movable mold 91 is held such that its parting surface 91 a is flush with the parting surface 91 a of the movable mold holder 93.

  The core pin 60 is inserted concentrically into the cylindrical portion cavity 92b of the cavity 92 of the movable die 91, and the tip surface of the core pin 60 is a thrust bearing molding portion 63. It is formed into a shape. A radial dynamic pressure bearing forming portion 62 is formed to form a dynamic pressure groove 54 for generating dynamic pressure on the outer peripheral surface that follows this.

  The movable mold mounting plate 95 is formed with a plurality of through holes 95a having the same diameter and the same center as the through holes 91c opened in the movable mold 91.

  The core pin 60 is integrated with the through-hole 91b of the movable mold 91 by a movable mold mounting plate 95 at the rear part thereof.

  The ejector pin 94 is inserted into the through-hole 91c of the movable-side mold 91 and the through-hole 95a of the movable-side mold mounting plate 95, and its tip is movable so that the flange portion 56 of the dynamic pressure bearing member 30E can be pressed. The side mold 91 is assembled so as to remain at a position where it forms the same surface as the surface of the flange cavity 92a.

  Note that other mold parts on the movable side 90 (guide pins, support pins, spacer blocks, movable side mounting plates, ejector plates with ejector pins attached, return pins, springs, etc.) and tension links for operating three plates Illustration of the plastic bolt, stop bolt, heater for mold temperature control, etc. is omitted.

  When the dynamic pressure bearing member 30E is injection-molded using the injection molding die 70 having the above-described configuration, the movable side 90 is moved in the direction of the arrow Xa to closely contact and fasten with the fixed side 80, and then The molten resin Mr injected from the injection nozzle of an injection molding machine (not shown) into the injection molding die 70 was provided at the center of the fixed side die 85 through the spool 81a and the runner 85a. After flowing into the cavity 92 of the movable mold 91 from the one-point pinpoint gate 85b and uniformly filling the circumferential direction of the flange cavity 92a of the cavity 92 of the movable mold 91, the cylindrical cavity 92b is sequentially filled. Filled.

  Next, after holding and cooling, as shown by the arrow Xb in FIG. 28, the movable mold 91 is retracted from the fixed mold 85 by opening the mold of the injection molding machine, and the parting surface 85c and the parting surface At the same time, the core pin 60 is also retracted together with the retraction of the movable die 91, and is released from the molded dynamic pressure bearing member 30E by forcible removal. However, in this case, the ejector pin 94 continues to push the flange portion 56 of the dynamic pressure bearing member 30E.

  Next, the ejector pin 94 that has continued to push the flange portion 56 of the dynamic pressure bearing member 30E is retracted in the direction of the arrow Xb, and the dynamic pressure bearing is removed from the parting surface 85c of the fixed mold 85 with a wiper (not shown). If the member 30E is scraped off, it is cut from the gate portion 85b, and the product 30E shown in FIG. 25A as a product is obtained.

  Next, a space between the fixed mold 85 and the runner stripper plate 84 and a space between the runner stripper plate 84 and the fixed mounting plate 83 are opened by a pull link, a plastic bolt, and a stop bolt (not shown).

  When the dynamic pressure bearing member 30E is injection molded using the core pin 60 and the injection molding die 70 having such a structure, the pin of the core pin 60 is formed on the inner peripheral surface 53 of the bearing hole 51 of the cylindrical portion 50. The groove Mr (concave portion) is transferred as a dynamic pressure groove land portion (convex portion) 55, and the land portion L (convex portion) of the core pin 60 is transferred as a dynamic pressure groove 54 (concave portion).

  As described above, since the edge portion E of the pin groove Mr of the core pin 60 is chamfered in a substantially R shape, the groove bottom corner portion 54e of the dynamic pressure groove 54 is processed in a substantially R shape in the dynamic pressure bearing member 30E. The portions other than the dynamic pressure groove 54 are recessed portions 57 having substantially the same depth as the dynamic pressure groove 54. In actual use, the recesses 57 other than the dynamic pressure groove 54 serve as a lubricating oil reservoir.

  The machining amount of the substantially R shape in the dynamic pressure bearing member 30 </ b> E is 5 to 40% of the depth of the dynamic pressure groove 54. It is said that deformation and scratches occur in the land portions 55 at the time of release of the molded hydrodynamic bearing member 30E when it is less than 5%. Further, the larger the R-shaped machining amount is, the better for deformation and scratches at the time of mold release, but if it exceeds 40%, the performance as a hydrodynamic bearing is lowered, so the upper limit is made 40%.

Further, as shown in FIG. 29, as the core pin 60b that can be more easily removed from the dynamic pressure bearing member 30E, not only the edge portion E of the land portion L for the radial dynamic pressure groove, but also the groove bottom of the pin groove Mr. By processing the corner portion Bc into a substantially R shape, the groove bottom corner portion 54e of each dynamic pressure groove 54 and the edge 55E of each land portion 55 of the dynamic pressure bearing member 30F that has been injection-molded are substantially R-shaped. As shown in FIG. 30, the hydrodynamic bearing in which the groove bottom corners 54e of the hydrodynamic grooves 54 and the edges 55E of the land portions (convex portions) 55 are formed in a substantially R shape. Member 30F is obtained, and the edge 55E of each groove bottom corner portion 54e and each land portion (convex portion) 55 is formed in a substantially R shape, whereby the dynamic pressure bearing member 30F is more than the dynamic pressure bearing member 30E. Is from injection mold to dynamic pressure bearing part 30F is a more can be more unreasonable excl.
Japanese Patent Laid-Open No. 2001-65570 (pages 3 to 4, FIGS. 1 to 4)

  However, as described above, in the conventional method for forming the dynamic pressure groove 54 on the inner peripheral surface of the dynamic pressure bearing member, a resin having a certain elastic modulus is injected into the cavity of the mold into which the core pin 60 is inserted. 26B and 25B, as shown in FIGS. 26B and 25B, the straight portion H is formed in the land portion L of the core pin 60, and the stray flange portion J is formed in the dynamic pressure groove 54 of the dynamic pressure bearing member 30E or 30F. Since both of them face each other perpendicular to the forcing force F, it becomes a resistance force, and the forcing force F must be taken large, and is unnecessary for the dynamic pressure bearing member 30E or 30F. However, there is still a problem that it is easily damaged.

  Further, in the injection molding of the retaining washer engaging groove for engaging the retaining washer 49 for preventing the rotation shaft 31C from being prevented from slipping in the bearing unit 30D as shown in FIG. 24, the diameter of the annular projection for that purpose is the dynamic pressure. It is necessary to form the core pin thicker than the diameter of the groove forming portions 62a, 62b, and if such a core pin is forcibly removed after the formation of the dynamic pressure bearing member in the same manner as the manufacturing method of the prior art, the molded dynamic pressure bearing The dynamic pressure continuous grooves Ra and Rb formed on the inner peripheral surface of the working member are further damaged or deformed due to the presence of the retaining washer engaging groove.

  The present invention is intended to solve such a problem, a retaining washer engaging groove forming annular protrusion is formed on the outer peripheral surface of the tip portion, and a radial hydrodynamic bearing forming portion is formed on the outer peripheral surface following this, Even if the former core pin having a diameter larger than the latter diameter is forcibly removed from the molded dynamic pressure bearing member, it is difficult to damage or deform the radial dynamic pressure groove with the retaining washer engaging groove forming projection. It is an object of the present invention to obtain a dynamic pressure bearing member, a molding die, a manufacturing method thereof, and a dynamic pressure bearing that can be easily forcibly extracted even if the forcible extraction force is small.

  Therefore, in order to achieve the above object, the dynamic pressure bearing member of the present invention has a predetermined length, a hole in which the rotary shaft is inserted has a circular hole, and one end of the rotary shaft is inserted. It consists of a bottomed plastic cylinder opening as a mouth, a radial dynamic pressure groove of a predetermined shape on the inner peripheral surface of the circular hole of the cylinder part, a thrust bearing part on the bottom part, and the vicinity of the thrust bearing part A retaining washer engaging groove is integrally formed on the upper side.

  In another dynamic pressure bearing member of the present invention, a circular slit having a predetermined length that opens on an end surface of the resin cylindrical portion on the rotary shaft insertion port side of the dynamic pressure bearing member is an axial direction of the circular hole. And is formed concentrically.

  And it is preferable to form a flange part integrally in the outer side of the said thrust bearing part of the said cylinder part.

  Moreover, it is preferable that the said thrust bearing part is formed in a spherical part.

  The circular slit is preferably formed so as to extend to the thrust bearing portion.

  Furthermore, it is preferable that two or more stages of dynamic pressure grooves are formed in the axial direction on the inner peripheral surface of the cylindrical portion.

  Furthermore, the dynamic pressure groove is preferably formed as a continuous V-shaped groove.

  Still further, the dynamic pressure bearing member is formed by resin injection molding, and when the dynamic pressure bearing member is forcibly removed from the injection mold, the sectional shape of the dynamic pressure groove in the forcible removal direction is trapezoidal. It is formed in a concave shape, and an inclination angle of at least the rear inclined surface in the direction of forced removal of the trapezoidal concave shape is formed at an angle of 135 ° to 150 °, and a bottom corner portion and an opening corner portion of the dynamic pressure groove are formed It is preferable to be chamfered or formed in a substantially R shape.

  Furthermore, the dynamic pressure bearing member is formed by resin injection molding, and when the dynamic pressure bearing member is forcibly removed from the injection mold, the sectional shape of the dynamic pressure groove in the forcible removal direction is circular. It is preferable that it is formed in an arcuate concave surface.

  The injection mold according to the present invention has a predetermined length, and is made of a resin with a bottom, in which a bearing hole having a circular inner cross section into which a rotating shaft is inserted is opened and one end is opened as a rotating shaft insertion port. A cylindrical dynamic pressure groove having a predetermined shape is formed on the inner peripheral surface of the bearing hole of the cylindrical portion, a thrust bearing portion is integrally formed on the bottom portion, and a retaining washer engaging groove is integrated above the thrust bearing portion. An injection mold for forming a fluid pressure bearing member formed in a general manner, the core pin forming the bearing hole, the radial dynamic pressure groove, the thrust bearing portion, the retaining washer engaging groove, and the cylinder A fixed-side mold that forms the part and a movable-side mold that forms the cylindrical part, and the movable-side mold and the core pin are individually configured to move in the same direction, and are necessary The core pin can be rotated according to And wherein the are.

  Further, the injection mold of the present invention is made of a resin with a bottom having a predetermined length, a hole having a circular inner cross section into which the rotation shaft is inserted, and one end being opened as a rotation shaft insertion port. A cylindrical portion, a radial dynamic pressure groove of a predetermined shape on the inner peripheral surface of the circular hole of the cylindrical portion, a thrust bearing portion on the bottom, and a retaining washer engagement groove on the upper vicinity of the thrust bearing portion are integrated. An injection molding mold for molding a dynamic pressure bearing member formed in a specific manner, and a protrusion having a predetermined shape for forming the radial dynamic pressure groove of the dynamic pressure bearing member on an outer peripheral surface; A retaining washer engaging groove forming projection for forming the retaining washer engaging groove of the dynamic pressure bearing member on the distal end side, and a thrust bearing portion of the dynamic pressure bearing member on the distal end surface Thrust bearing formed with a core pin formed with molded part And wherein the are.

  Furthermore, another injection mold according to the present invention has a predetermined length, has a bottom with a circular hole in the inner section into which the rotary shaft is inserted, and one end opened as a rotary shaft insertion port. A cylindrical portion made of resin, a radial dynamic pressure groove of a predetermined shape on the inner peripheral surface of the circular hole of the cylindrical portion, a thrust bearing portion on the bottom portion, and a retaining washer engaging groove on the upper vicinity of the thrust bearing portion Is formed integrally, and a circular slit having a predetermined length that opens at an end face of the resin cylinder portion on the rotary shaft insertion port side is formed in the axial direction of the circular hole and concentrically. An injection molding die for molding a dynamic pressure bearing member, and a protrusion having a predetermined shape for forming the radial dynamic pressure groove of the dynamic pressure bearing member on an outer peripheral surface; A retaining washer for forming the retaining washer engaging groove of the fluid dynamic bearing member A core pin on which a groove forming projection, a thrust bearing forming portion for forming the thrust bearing portion of the dynamic pressure bearing member on the tip surface are formed, a cylindrical portion cavity forming the cylindrical portion, and the cylinder The cylindrical projection for forming the cylindrical portion having an inner circumferential surface having a circular cross section that forms a cavity forming the thrust bearing molding portion continuously with the portion cavity, and the circular slit concentrically between the cylindrical projections It is characterized by comprising a movable mold in which a cylindrical projection for forming a cylinder is formed.

  It is preferable that the tube portion side of the retaining washer engaging groove forming protrusion formed near the tip of the core pin is formed in a tapered surface or an R shape that is lowered.

  And it is preferable that the said protrusion on the outer peripheral surface of the said core pin is formed in 2 steps | paragraphs or more at predetermined intervals in the axial direction.

  Moreover, it is preferable that the said protrusion on the outer peripheral surface of the said core pin is a continuous V-shaped protrusion.

  Moreover, it is preferable that the corners of the protrusions formed on the outer peripheral surface of the core pin are chamfered.

  Further, the cross-sectional shape of the protrusion formed on the outer peripheral surface of the core pin is an acute angle with respect to the forcible removal direction of the dynamic pressure bearing member and with respect to the outer peripheral surface of the core pin, and the acute angle is from 30 °. It is preferable that the protrusions are formed at an angle of 45 °.

  Furthermore, a cross-sectional shape corresponding to the dynamic pressure groove shape is formed on the outer peripheral surface of the core pin by a trapezoidal protrusion, and an inclination angle of at least a rear slope in the forcibly removing direction of the trapezoidal protrusion is the core pin. Are formed with an acute angle with respect to the outer peripheral surface, and the acute angle is formed at an angle of 30 ° to 45 °, and the surface corner of each trapezoidal protrusion and the base of each trapezoidal protrusion are chamfered, or substantially It is preferably formed in an R shape.

  Still further, a cross-sectional shape corresponding to the dynamic pressure groove shape is formed on the outer peripheral surface of the core pin by a partially arcuate protrusion, and the base of the partially arcuate protrusion is chamfered or substantially R-shaped. It is preferable to be formed.

  In addition, the method for manufacturing a dynamic pressure bearing member according to the present invention has a bottomed structure having a predetermined length, a hole having a circular inner cross section into which the rotary shaft is inserted, and one end being opened as a rotary shaft insertion port. A radial dynamic pressure groove of a predetermined shape on the inner peripheral surface of the circular hole of the cylindrical portion, a thrust bearing portion on the bottom portion, and a locking washer engaged near the thrust bearing portion. When manufacturing a dynamic pressure bearing member in which grooves are integrally formed by injection molding, a molten resin injection gate is formed facing the parting surface side, and a fixed mold and the fixed mold And a cavity that forms at least a part of a member for a hydrodynamic bearing to be formed, and a through hole having a circular cross section that penetrates the parting surface. Is formed A movable die and a thickness that can be inserted into the through hole of the movable die, at least facing the cavity, and for forming the radial dynamic pressure groove of the dynamic pressure bearing member on the outer peripheral surface thereof A protrusion having a predetermined shape, a retaining washer engaging groove forming protrusion for forming the retaining washer engaging groove of the dynamic pressure bearing member on the distal end side, and the thrust of the dynamic pressure bearing member on the distal end surface An injection molding die having a thrust pin forming part for forming a bearing part and capable of moving in the same direction as the movement of the movable mold, but having a core pin that moves individually is provided. Using the core pin inserted into a predetermined position in the through-hole of the movable mold, the parting surface of the movable mold is brought into contact with and closely contacted with the parting surface of the fixed mold The fixed side metal And the molten resin is injected and filled from the molten resin injection gate into the cavity formed by the movable side mold, the injection injection, and after the filled molten resin is cured, the fixed side mold and The fastening of the movable side mold is released, the movable side mold is retracted from the parting surface of the fixed side mold and the outer peripheral surface of the hardened dynamic pressure bearing member, and then the hardened dynamic pressure The core pin from the dynamic pressure bearing member or the core pin from the dynamic pressure bearing member to the axial direction of the dynamic pressure bearing member in a state where the movable mold does not exist around the bearing member. To obtain the fluid dynamic bearing member.

  Further, in another method for manufacturing a dynamic pressure bearing member of the present invention, a hole having a predetermined length, a circular section of the inside into which the rotating shaft is inserted is opened, and one end is opened as a rotating shaft insertion port. The bottom of the cylindrical hole has a radial dynamic pressure groove of a predetermined shape, a thrust bearing portion at the bottom, and an upper portion in the vicinity of the thrust bearing portion. A washer engaging groove is integrally formed, and a circular slit having a predetermined length that opens to the end surface of the resin cylinder portion on the rotary shaft insertion port side is formed in a concentric manner in the axial direction of the circular hole. In manufacturing the hydrodynamic bearing member formed in the mold by injection molding, a molten resin injection gate is formed facing the parting surface side, and the fixed side mold is moved forward and backward with respect to the fixed side mold. Party that can be attached to the parting surface A cylindrical part cavity that forms at least the cylindrical part of the dynamic pressure bearing member to be molded, and a circular cross section that forms a cavity that forms the thrust bearing molded part continuously to the cylindrical part cavity. A movable mold in which the cylindrical projection for forming the cylindrical portion having an inner peripheral surface and a cylindrical projection for forming the circular slit concentrically between the cylindrical projection are formed; and the movable mold A projection having a predetermined shape for forming a dynamic pressure groove on the outer peripheral surface thereof is formed in a thickness that can be inserted into the through-hole, and a retaining washer engaging groove on the outer periphery around the tip portion The forming projection has a thrust bearing forming portion formed on the tip surface thereof, and can move in the same direction as the movement of the movable mold, or can move in the same direction as the movement of the movable mold But The parting of the fixed mold in a state where the core pin is inserted into a predetermined position in the through hole of the movable mold, using an injection mold configured to include a core pin that moves to The parting surface of the movable mold is abutted and brought into close contact with the surface and fastened, and the molten resin is injected from the molten resin injection gate into the cavity formed by the fixed mold and the movable mold. After the injection resin is filled and the molten resin filled is cured, the fastening between the fixed side mold and the movable side mold is released, and the parting surface of the fixed side mold and Forcibly removing the movable side mold from the outer peripheral surface of the cured dynamic pressure bearing member from the dynamic pressure bearing member in the axial direction of the dynamic pressure bearing member to obtain the dynamic pressure bearing member. Features.

  In the case of the method for manufacturing the dynamic pressure bearing member, it is more preferable that the core pin is rotated and the core pin is forcibly removed in the axial direction of the dynamic pressure bearing member.

  Moreover, it is preferable that the said protrusion on the outer peripheral surface of the said core pin is formed in two or more steps | paragraphs at predetermined intervals in the axial direction.

  Furthermore, it is preferable that the protrusions on the outer peripheral surface of the core pin are continuous V-shaped protrusions.

  And it is preferable that the rotation direction of the said core pin is a point direction of a V-shaped protrusion.

  Further, when the core pin is forcibly removed in the axial direction of the dynamic pressure bearing member in which two or more stages of dynamic pressure grooves are formed on the inner peripheral surface of the cylindrical portion, the angle at which the core pin is rotated is the core pin It is preferable that the angle is such that a series of protrusions of the core pin does not fit into the adjacent dynamic pressure grooves in the axial direction in which force is removed.

  Furthermore, it is preferable that the corners of the protrusions formed on the outer peripheral surface of the core pin are chamfered.

  Still further, the cross-sectional shape of the protrusion formed on the outer peripheral surface of the core pin is an acute angle with respect to the forcibly removing direction of the dynamic pressure bearing member, and with respect to the outer peripheral surface of the core pin, and the acute angle is 30. The protrusions are preferably formed at an angle of from 45 ° to 45 °.

  Furthermore, a cross-sectional shape corresponding to the dynamic pressure groove shape is formed on the outer peripheral surface of the core pin by a trapezoidal protrusion, and an inclination angle of at least a rear slope in the forcibly removing direction of the trapezoidal protrusion is the An acute angle with respect to the outer peripheral surface of the core pin, the acute angle being formed at an angle of 30 ° to 45 °, and a surface corner portion of each trapezoidal protrusion and a base portion of each trapezoidal protrusion are chamfered, or It is preferably formed in a substantially R shape.

  Still further, a cross-sectional shape corresponding to the dynamic pressure groove shape is formed on the outer peripheral surface of the core pin by a partially arcuate protrusion, and the base of the partially arcuate protrusion is chamfered or substantially R-shaped. It is preferable to be formed.

  Furthermore, it is preferable that the protrusion of the core pin is formed so that a V-shaped protrusion is continuous around the outer peripheral surface.

  And furthermore, it comprises a bottomed resin cylinder portion having a predetermined length, a circular hole in the inner cross section into which the rotating shaft for the rotating device is inserted, and one end opened as a rotating shaft insertion port, A radial dynamic pressure groove having a predetermined shape is integrally formed on the inner peripheral surface of the circular hole of the cylindrical portion, a thrust bearing portion is formed on the bottom portion, and a retaining washer engaging groove is formed in the vicinity of the upper portion of the thrust bearing portion. A rotary shaft insertion hole having a diameter that can be inserted into the retaining washer engagement groove and having a diameter that allows the rotation shaft to be inserted is formed in the center portion, and radially from the rotation shaft insertion hole. A plastic disc-shaped retaining washer having a plurality of incisions toward the peripheral portion and bent, and an end surface supported by the thrust bearing portion, and an outer peripheral surface pivotally supported by the radial bearing portion, A stopper is attached to the outer peripheral surface near the end surface. The rotary shaft for the rotating device in which a shear engaging groove is formed, and the retaining washer is bent from the rotational shaft insertion port of the dynamic pressure bearing member and inserted into the retaining washer engaging groove. The outer peripheral edge of the retaining washer is fitted, the rotational shaft is inserted into the rotational shaft insertion hole of the retaining washer from the rotational shaft insertion port, and the inner peripheral edge of the rotational shaft insertion hole of the retaining washer is secured to the rotational shaft. The rotary shaft is configured to be fitted into a washer engaging groove so that the rotating shaft does not come out of the dynamic pressure bearing member.

  Therefore, according to the present invention, when the dynamic pressure bearing member is released from the movable mold after injection molding, the molded dynamic pressure bearing member is forcibly removed from the core pin, or the core pin is used for the dynamic pressure bearing. Although it is forcibly removed from the member, there is no movable mold on the outer peripheral surface of the molded hydrodynamic bearing member, and there is free space (including a circular slit), so the radial movement of the core pin The pressure bearing forming portion and the retaining washer engaging groove forming annular projection make the dynamic pressure bearing member easy to expand in the diametrical direction, and are formed in comparison with the conventional method of manufacturing a dynamic pressure bearing member. Since the dynamic pressure bearing member is not held by the movable side mold, the forcible extraction force is small, and the extraction can be performed without applying unnecessary force.

  Further, the edge of the protrusion of the radial dynamic pressure bearing forming portion of the core pin is chamfered, formed in a substantially R shape, or formed on an inclined surface with respect to the forcibly removing direction such as a trapezoid or an arc shape. Therefore, the dynamic pressure bearing member can be forcibly removed from the core pin with a weaker force.

  Furthermore, when the core pin or the dynamic pressure bearing member is forcibly removed, the core pin is rotated so that a dynamic pressure groove forming portion formed on the outer peripheral surface of the core pin is formed at the rear in the forcible removal direction. It can prevent fitting in the dynamic pressure groove.

Therefore, according to the dynamic pressure bearing member of the present invention,
1. 1. A good radial bearing is formed that is less likely to be scratched or deformed. 2. A radial bearing, a thrust bearing, and a retaining washer engaging groove are formed integrally. 3. The number of parts can be greatly reduced from the item 2 above. 4. The cost of the hydrodynamic bearing member can be greatly reduced from the item 3 above. The retaining washer can be easily inserted into the dynamic pressure bearing member. Also, according to the injection mold of the present invention,
1. In particular, a single core pin can form a radial bearing, a thrust bearing, and a retaining washer engagement groove on the inner periphery of the hydrodynamic bearing member. Since an excessive force is not applied to the core pin, the life is extended. Further, according to the method for manufacturing a fluid dynamic bearing member of the present invention,
1. 1. When forcibly removing, the radial bearing formed on the inner peripheral surface of the dynamic pressure bearing member is not easily damaged or deformed. 2. Less force is required when unreasonable, and the flexibility of the injection molding machine is increased. The force required to remove the force is small, the restriction on the elastic modulus of the resin used for the dynamic pressure bearing member can be relaxed, and the degree of freedom in resin selection increases. When using expensive resin, if the shaft diameter is thin and the outer diameter of the cylinder part attached to the housing part is large, the amount of resin used can be reduced by inserting a circular slit in the cylinder part, especially the width of the circular slit. 4. If it is widened, the amount of resin used can be further reduced. If the thickness of the cylindrical part on which the radial bearing part is formed is reduced from the item 4, a good dynamic pressure bearing member can be obtained without causing further damage or deformation. According to the bearing
1. Numerous excellent effects are obtained, such as the rotating shaft not easily coming out of the hydrodynamic bearing.

  Hereinafter, the member for a dynamic pressure bearing, the molding die thereof, the manufacturing method thereof, and the dynamic pressure bearing of the present invention will be sequentially described with reference to the drawings.

  FIG. 1 is an enlarged sectional view of a fluid dynamic bearing member according to a first embodiment of the present invention, FIG. 2 is an enlarged side view of a core pin used for molding the fluid dynamic bearing member shown in FIG. 1, and FIG. 4 is an enlarged cross-sectional side view of the movable side mold in which the core pin and the ejector pin shown in FIG. 2 are assembled. FIG. 4 is composed of a fixed side mold and a movable side mold for injection molding the dynamic pressure bearing member of the present invention. FIG. 5 is a cross-sectional view of an example of an injection mold shown in a state where both are fastened, FIG. 5 is a cross-sectional view of the state where the injection mold shown in FIG. 4 is opened, and FIG. FIG. 7 is a cross-sectional view showing a state where the hardened hydrodynamic bearing member is released from the parting surface of the fixed mold, and FIG. 7 shows the operation following the operation shown in FIG. FIG. 8 is a cross-sectional view showing the moment when the core pin of the movable mold and the dynamic pressure bearing member are forcibly removed. FIG. 9 is a sectional view showing a state where the core pin of the movable mold and the dynamic pressure bearing member are completely removed, and FIG. 9 shows the operation following FIG. FIG. 2 is a cross-sectional view showing the relationship between a dynamic pressure bearing member and an injection mold in a state obtained by the method for manufacturing a dynamic pressure bearing member of the present invention.

  The injection mold of the present invention shown in FIG. 4 has only a fixed side mold 85 and a fixed side mold holder 86 on the fixed side 80, and a movable side mold 91 and a core pin on the movable side 90. 30A, only the movable side mold holder 93, the ejector pin 94, and the coil spring 95 attached to the tip thereof are shown, and illustration of components not directly related to the method of manufacturing the dynamic pressure bearing member of the present invention is omitted. The principle diagram is shown. The same applies to FIGS. 5 to 9.

  It should be noted that the configurations and structural parts of the dynamic pressure bearing member and the injection molding die of this embodiment will be described with the same configurations and structural parts as those of the prior art.

  First, with reference to FIG. 1 to FIG. 9, the structure and structure of a fluid dynamic bearing member, its molding die, its manufacturing method, and fluid dynamic bearing according to a first embodiment of the present invention will be described.

  In FIG. 1, reference numeral 30A denotes a fluid dynamic bearing member according to the first embodiment of the present invention. The dynamic pressure bearing member 30A is integrally formed by injection molding of resin, and the cylindrical portion 50 has an inner peripheral surface 53 having a circular cross section, and the rotary shaft 31 is a rotary shaft insertion port 51a. Is formed with a bearing hole 51 of a bottomed 52 that can be inserted through the inner circumferential surface 53, and a V-shaped dynamic pressure groove (recess) 54 and a dynamic pressure groove shown in FIG. A radial bearing portion R is formed by alternately forming land portions (convex portions) 55 at two-stage dynamic pressure continuous grooves Ra and Rb at a predetermined pitch in parallel with a predetermined interval in the major axis direction. At the same time, a part of the spherical thrust bearing portion S is formed at the center of the bottom portion 52 subsequent thereto. Further, a retaining washer engaging groove 57 that is a feature of the present invention is formed in a portion close to the thrust bearing portion S between the thrust bearing portion S and the dynamic pressure groove Rb. Further, a flange portion 56 is integrally formed on the outer peripheral portion of the bottom portion 52, and this also serves as a member attached to the electronic device.

  Next, the core pin 60A, which is one mold constituting the injection mold of the present invention shown in FIG. 2, will be described.

The core pin 60A has dynamic pressure groove forming portions 62a and 62b formed on the outer peripheral surface 61 thereof, and the tip surface of the core pin 60A is formed in a thrust bearing forming portion 63A of a partial spherical recess. The retaining washer engaging groove forming annular protrusion 64, which is a feature of the present invention, is formed in a portion close to the thrust bearing forming portion 63A side between the dynamic pressure groove forming portion 62b and the thrust bearing forming portion 63A. The edge on the dynamic pressure groove forming portion 62b side of the retaining washer engaging groove forming annular protrusion 64 is formed on a tapered surface 64a that falls to the dynamic pressure groove forming portion 62b side.
On the outer peripheral surface 31 of the tip portion of the core pin 30, two stages of dynamic pressure grooves Ra in parallel with a predetermined interval in the axial direction on the inner peripheral surface 53 (FIG. 1) of the cylindrical portion 50 of the dynamic pressure bearing member 30A, The dynamic pressure groove forming portions 62a and 62b corresponding to the dynamic pressure grooves Ra and Rb are formed so that Rb is formed, but these dynamic pressure groove forming portions 62a and 62b are continuous at a predetermined interval. The V-shaped cross section is composed of protrusions, and the size, angle, pitch, groove width, groove depth, etc. of these V-shaped protrusions are formed exactly the same.

  As shown in FIG. 3, the core pin 60A is assembled to a movable mold 91 on the movable side 90, and can move in the left-right direction as indicated by an arrow X, and V-shaped dynamic pressure as required. As shown by the symbol Xr in the direction of the V-shaped tip of the grooves Ra and Rb, the grooves Ra and Rb are assembled so that they can be rotated within a slight rotation angle range within one rotation.

  The movable mold 91 opens with a parting surface 91a that can be in close contact with a parting surface 85c of the fixed mold 85 to be described later, and a gate 85b of the fixed mold 85 on the parting surface 91a. A cavity 92, a single through hole 91b having a circular cross section penetrating through the central portion of the cavity 92, and a plurality of through holes 91c arranged evenly around the through hole 91b are formed.

  The cavity 92 is formed by a structure in which a flange portion cavity 92a capable of forming the flange portion 56 of the dynamic pressure bearing member 30A to be formed and a cylindrical portion cavity 92b for forming the cylindrical portion 50 of the dynamic pressure bearing member 30A are integrated. Has been. The ends of the plurality of through-holes 91c are open facing the flange cavity 92a.

  The movable-side mold holder 93 is formed with a recess 93a into which the movable-side mold 91 can be fitted and the same diameter as the through-holes 91b and 91c of the movable-side mold 91 so that their long axes are in a straight line. A through hole 93b and a plurality of through holes 93c are formed.

  The movable-side mold is configured such that the movable-side mold 91 is fitted into the recess 93 a of the movable-side mold holder 93, and the through-holes 91 b and 91 c of the movable-side mold 91 and the through-hole 93 b of the movable-side mold holder 93 are inserted. , 93c are aligned in a straight line in the axial direction, the core pin 60A is inserted into the through hole 91b and the through hole 93b, and the thrust bearing molding portion 63A of the core pin 60A is stopped at a predetermined position, for example, the center portion of the flange portion cavity 92a. The ejector pins 94 are inserted into the through holes 91 b and 93 c, respectively, and the tips of the coil springs 95 fixed to the tips of the ejector pins 94 are open surfaces opened in the flange cavity 92 a of the movable mold 91. It is assembled so that it faces to form the same surface.

  A plurality of these ejector pins 94 are equally provided around one cavity 92, and the plurality of ejector pins 94 move together at the same time. Is attached. The tip end of each coil spring 95 remains on the same surface facing the cylindrical cavity 92b, and is configured to never penetrate into the cylindrical cavity 92b when the molten resin Mr is injected and injected. Further, these ejector pins 94 are attached so as to be able to slide smoothly in the left-right direction indicated by the arrow X in the through hole 91c of the movable mold 91 and the through hole 93c of the movable mold holder 93. Yes.

  The movable mold 91 is configured so as to move together with the movable mold holder 93, and the core pin 30A and all the ejector pins 94 can be individually moved in the respective axial directions indicated by the symbol X. It is controlled by a rotating device (not shown) so that it can be rotated within a range of less than one rotation in the direction of the V-shaped tip of the V-shaped dynamic pressure grooves Ra and Rb as indicated by reference numeral Xr. It is configured.

  Although the cavity 92 is illustrated as being formed in the movable mold 91, a part of the cylindrical cavity 92b may be formed on the parting surface 85c of the fixed mold 85.

  On the other hand, the configuration and structure of the fixed mold 85 are the same as those shown in FIGS.

  Next, the manufacturing method of the dynamic pressure bearing member of the present invention for manufacturing the dynamic pressure bearing member of the present invention will be described with reference to FIGS.

  First, as shown in FIG. 4, the fixed mold 85 is attached to the recess of the fixed mold holder 86, the movable mold 91 is mounted to the recess 93a of the movable mold holder 93, and the core pin 60A is attached. The through hole 91b of the movable side mold 91 and the through hole 93b of the movable side mold holder 93 arranged in a straight line in the through hole 91b are inserted, and the thrust bearing molding portion 63A at the tip portion is inserted into the flange portion. The ejector pin 94 is stopped at a predetermined position in the middle of the cavity 92a, and each ejector pin 94 is inserted into each through hole 91c of the movable mold 91 and each through hole 93c of the movable mold holder 93 in a straight line. With the tip of the coil spring 95 attached to the tip of 94 facing the flange cavity 7a being stopped at the same plane, the movable mold 91 is moved to the left of the X axis in the figure. The parting surface 91a of the movable-side mold 91 is abutted and brought into close contact with the parting surface 85c of the fixed-side mold 85, and is formed by the fixed-side mold 85 and the movable-side mold 91. The molten resin Mr is injected and injected into the cavity 92 from the molten resin gate 85b (FIG. 4).

  Next, after the injection and injection, and the filled molten resin Mr is cured, as shown in FIG. 5, the fastening between the fixed side mold 85 and the movable side mold 91 is released. From the parting surface 85c of the mold 85 and the outer peripheral surface of the cured and molded dynamic pressure bearing member 20, the movable side mold 91 is retracted together with the movable side mold holder 93 in the right direction of the X axis. In this case, the dynamic pressure bearing member 30 </ b> A remains pressed by the ejector pins 94 and the coil springs 95 on the parting surface 85 c of the fixed mold 85. Also, the core pin 60A does not move.

  Thereafter, as shown in FIG. 6, the entire movable side is further retracted slightly, and the dynamic pressure bearing member 30A is separated from the gate 85b and the parting surface 85c of the fixed side mold 85.

  Next, as shown in FIG. 7, the ejector pins 94 and the coil springs 95 remain in the positions shown in FIG. 6, and the movable die 91 does not exist around the molded dynamic pressure bearing member 30A. In the state, the core pin 60A is rotated within a slight angular range within one rotation in the direction of the V-shaped tip of the V-shaped dynamic pressure grooves Ra and Rb indicated by the symbol Xr using a drive mechanism (not shown), and The core pin 60A is moved in the long axis direction to the right of the X axis indicated by the symbol X, and the core pin 60A is forcibly removed from the bottom 52 of the dynamic pressure bearing member 30A.

  Then, the drive mechanism is further operated, and the core pin 60A is forcibly removed from the dynamic pressure bearing member 30A while moving the core pin 60A in the right direction of the X axis as shown in FIG. Retreat until.

  Next, as shown in FIG. 9, when the ejector pin 94 and the coil spring 95 are moved in the right direction of the X axis indicated by the symbol X, the dynamic pressure bearing member 30A is separated from the injection mold and dropped. (Symbol Y).

  Through such an injection molding process, the thrust bearing S is formed on the bottom 52 having a circular cross section as shown in FIGS. 1 and 9, and the retaining washer engaging groove 57 is formed on the inner peripheral surface 53 of the cylindrical portion 50 in the vicinity thereof. Further, in the inner peripheral direction of the inner peripheral surface 53 of the central portion of the cylindrical portion 50, for example, radial dynamic pressure portions Ra and Rb including a series of V-shaped dynamic pressure grooves 54 as shown in FIG. 30A can be manufactured by opening the shaft and parallelly forming two stages.

  In the above description, it has been described that when the core pin 60A is forcibly removed, the core pin 60A is rotated in the direction of Xr (described later) and forcibly removed in the right direction of the X axis of X. It is not an essential requirement to rotate in this manner. However, it is preferable to rotate the core pin 60A when the core pin 60A is forcibly removed. The preferable reason will be described with reference to FIGS.

  FIG. 10 is an explanatory view when the core pin is forcibly removed only in the axial direction (X-axis direction) of the dynamic pressure bearing member, and FIG. 10A shows a radial formed on the inner peripheral surface of the dynamic pressure bearing member. FIG. 11B is a development view in which a development view of the protrusions formed on the outer peripheral surface of the core pin is superimposed on a development view of the radial dynamic pressure groove in FIG. FIG. 2A is an explanatory diagram of the case where the dynamic pressure bearing member is forcibly removed in the axial direction, and FIG. 3A is a development of the radial dynamic pressure groove formed on the inner peripheral surface of the dynamic pressure bearing member. FIG. 1 and FIG. 2B are developed views in which the developed views of the radial dynamic pressure grooves in FIG. 1A are overlapped with the developed views of the protrusions formed on the outer peripheral surface of the core pin.

  In the method of manufacturing the dynamic pressure bearing member of the first embodiment, when the core pin 60A is forcibly removed from the dynamic pressure bearing member 30A, the core pin 60A is slightly rotated within one rotation in the state of FIG. The dynamic pressure bearing member 30A is rotated at a dynamic angle and is forcibly removed in the right direction of the X axis.

  If the core pin 60A is not rotated as described above, a series of dynamic pressure groove forming portions (protrusions) 62b of the radial dynamic pressure bearing forming portion 62 of the core pin 60A that has been forcibly removed first is shown in FIG. 10B. As described above, it falls into the radial dynamic pressure groove Ra. That is, for example, the two-stage hydrodynamic groove forming portions 62a and 62b made of V-shaped protrusions formed on the outer peripheral surface 61 of the core pin 60A shown in FIG. When the two-stage dynamic pressure grooves Ra and Rb having the same V size, angle, pitch, groove width, groove depth and the like are formed on the inner peripheral surface of the core pin 60A, the dynamic pressure bearing is used. It is assumed that the member 30A is forcibly removed. In FIG. 10A, the radial dynamic pressure grooves Ra and Rb formed by the two-stage dynamic pressure grooves 54 and the land portions 55 formed on the inner peripheral surface 53 of the cylindrical portion 50 of the dynamic pressure bearing member 30 </ b> A are 360. FIG. 4 is a development view showing the entire circumference of °.

  In such a case, if the core pin 60A is forcibly removed from the dynamic pressure bearing member 30A only in the right direction of the X-axis indicated by the symbol X as described above, the protrusions 62a and 62b of the core pin 60A are respectively exposed to the radial dynamic pressure grooves Ra, Next, the dynamic pressure groove forming portion 62b, which is extracted from Rb and formed with the radial dynamic pressure groove Rb, falls into the respective dynamic pressure grooves 54 of the radial dynamic pressure groove Ra as shown by hatching in FIG. 10B. . Further, by further forcibly removing, the core pin 60A can be completely removed from the dynamic pressure bearing member 30A for the first time.

  As is apparent from the forcibly removed state, the radial dynamic pressure groove Ra is forcibly removed by the dynamic pressure groove forming part 62a and then the dynamic pressure groove forming part 62b, and the radial dynamic pressure groove Ra is formed by the protrusion 62a. , 62b depending on the shape, it is exposed to a state in which it is easily damaged or deformed. Further, in the case of the present invention, the retaining washer engaging groove forming annular protrusion 64 having a diameter larger than the diameter of the radial dynamic pressure bearing forming portion 62 is formed at the tip portion of the core pin 60A. Each radial dynamic pressure groove Ra, Rb is easily damaged. Scratching or deforming the radial dynamic pressure grooves Ra and Rb is not preferable for generating a good fluid dynamic pressure.

  Therefore, in the method of manufacturing the dynamic pressure bearing member of the present embodiment, as shown in FIGS. 6 to 8 and 11, the core pin 60A is placed in the direction indicated by the symbol Xr, that is, the V-shaped dynamic pressure groove. For example, in the axial direction of the dynamic pressure bearing member 30A in the right direction of the X-axis indicated by the symbol X, after rotating in the direction of the V-shaped tip of Ra and Rb with a slight rotation angle within one rotation, for example, a cam Then, the dynamic pressure bearing member 30A is forcibly removed using a shaft mechanism (not shown) or the like. In such a forced extraction method, first, the dynamic pressure groove forming portions (protrusions) 62a and 62b of the core pin 60A are extracted from the radial dynamic pressure grooves Ra and Rb, respectively, and then the thrust bearing forming portion of the core pin 60A. As shown in FIG. 11B, the dynamic pressure groove forming portion 62b on the 63A side is directed to the position of each dynamic pressure groove 54 constituting the radial dynamic pressure groove Ra, but does not fall off from the dynamic pressure grooves 54. The core pin 60A can be forcibly removed from the dynamic pressure bearing member 30A.

  The problem is that when the retaining washer engaging groove forming annular protrusion 64 passes through the radial dynamic pressure grooves Ra and Rb, the radial dynamic pressure grooves Ra and Rb are not scratched or deformed. When the core pin 60A of the present invention is forcibly removed from the dynamic pressure bearing member 30A, the movable side mold 91 and the movable side mold holder 93 do not exist from the dynamic pressure bearing member 30A. Since the outer peripheral surface 61 of the bearing member 30A is free space, when the dynamic pressure groove forming portions 62a and 62b and the locking washer engaging groove forming annular projection 64 having a diameter larger than these are forcibly removed, the dynamic pressure bearing The cylindrical part 50 of the member 30A can bulge slightly outward. Therefore, the dynamic pressure groove forming portions 62a and 62b of the core pin 60A and the retaining washer engaging groove forming annular projection 64 hardly damage or deform the radial dynamic pressure grooves Ra and Rb of the dynamic pressure bearing member 30A. The core pin 60A can be forcibly removed from the dynamic pressure bearing member 30A.

  In the description of the above embodiment, it has been described that the core pin 60A is forcibly removed from the molded dynamic pressure bearing member 30A, but conversely, the injection molded so that the molded dynamic pressure bearing member 30A is forcibly removed from the core pin 60A. It will be readily understood that a working mold may be constructed and the same effects are obtained.

  As described above, when the core pin 60A is forcibly removed, it is desirable to forcibly remove the core pin 60A without damaging or deforming the radial dynamic pressure grooves Ra and Rb of the dynamic pressure bearing member 30A as much as possible. The shape and structure of the dynamic pressure groove forming portions 62a and 62b of the core pin 60A may be the shape and structure of the core pin 9A as shown in FIG. 26 or the core pin 9b as shown in FIG. 29. In order to form the dynamic pressure bearing member 30A without deforming the pressure grooves Ra and Rb, it is preferable to use a core pin as shown in FIGS.

  FIG. 12 is a cross-sectional view showing a part of a first modified core pin of the first embodiment suitable for use in the present invention and a first modified hydrodynamic bearing member formed with the core pin, and FIG. FIG. 14 is a cross-sectional view showing a part of a second modified core pin of the first embodiment suitable for use in the invention and a part of a second modified dynamic pressure bearing member formed with the core pin, and FIG. 14 is used in the present invention. It is sectional drawing which showed a part of core member of the 3rd modified form and the member for dynamic pressure bearings of the 3rd modified form formed with this core pin.

  The core pin 60Aa according to the first modification shown in FIG. 12 has a hydrodynamic groove 54A, which will be described later, formed on the inner circumferential surface 53 of the dynamic pressure bearing member 30Aa on the outer circumferential surface 61. A trapezoidal protrusion 67 </ b> A, which is formed at an inclination angle symmetrical to 66, is formed. The slopes of the front slope 65 and the back slope 66 in the forcible removal direction indicated by the arrow X of these trapezoidal protrusions 67A with respect to the outer peripheral surface 61 of the core pin 60Aa are formed from 30 ° to 45 °, This is a mold in which the surface corners 67a of the protrusions 67A and the bases 67b of the trapezoidal protrusions 67A are chamfered or formed in a substantially R shape.

  When such a core pin 60Aa is inserted into the central portion of the movable mold 91 shown in FIGS. 3 and 4 to form a cavity 92 and molten resin is injected into the cavity 92 from the gate 85b, each trapezoidal shape is obtained. The trapezoidal concave dynamic pressure groove 54A having a shape corresponding to the protrusion 67A is transferred to the inner peripheral surface 53 of the cylinder that becomes the dynamic pressure bearing member 30Aa.

  In other words, the dynamic pressure bearing member 30Aa is continuously formed by a series of grooves in the circumferential direction of the entire inner circumference of the cylindrical portion by injection molding to form a radial bearing surface. The inclined front inclined surface 58 and the rear inclined surface 59 of the trapezoidal concave dynamic pressure grooves 54A are not surfaces perpendicular to the forcible removal direction X of the dynamic pressure bearing member 30Aa, but are not the rear inclined surfaces 59. The inclination angle is formed at an angle of 135 ° to 150 °. The angle of the front inclined surface 58 is formed symmetrically with the angle of the rear inclined surface 59. The bottom corner portion 54a and the opening corner portion 54b of the trapezoidal concave dynamic pressure groove 54A are chamfered or formed in a substantially R shape.

  Next, a second modified core pin 60Ab and a second form hydrodynamic bearing member 40B formed by the core pin 60Ab will be described with reference to FIG. Each of these is also shown in a sectional view as in FIG.

  The core pin 60Ab has a trapezoidal concave dynamic pressure groove 54B of a hydrodynamic bearing member 30Ab of the present modified embodiment, which will be described later, formed on the outer peripheral surface 61 thereof, and has a cross section rising substantially vertically from the outer peripheral surface 61 of the core pin 60Ab. An asymmetric trapezoidal projection 67B is formed by the vertical surface 65v and the rear inclined surface 66 having the same angle as the rear inclined surface 66 of the trapezoidal projection 67A of the first variation. The inclination angle of the rear inclined surface 66 in the forcible removal direction indicated by the arrow X of these trapezoidal protrusions 67B with respect to the outer peripheral surface 61 of the core pin 60Ab is formed from 30 ° to 45 °. The surface corner portion 67a and the base portion 67b of each of the trapezoidal protrusions 67B are molds that are chamfered or substantially R-shaped.

  When such a core pin 60Ab is inserted into the central through hole 91b of the movable mold 91 shown in FIGS. 3 and 4, a cavity 92 is formed, and molten resin Mr is injected into the cavity 92 from the gate 85b. The trapezoidal concave dynamic pressure groove 54B having a shape corresponding to each of the trapezoidal protrusions 67B is transferred to the inner peripheral surface 53 of the cylinder that becomes the dynamic pressure bearing member 30Ab.

  That is, the dynamic pressure bearing member 30Ab has a series of grooves formed by a trapezoidal concave dynamic pressure groove 54B in the direction of the inner peripheral surface of the resin cylinder by injection molding, and continues to the entire circumference of the inner peripheral surface 53. And a radial bearing surface is formed. These trapezoidal concave dynamic pressure grooves 54B are formed not by a plane perpendicular to the forcibly removing direction X but by an inclined rear inclined surface 59. The inclination angle of the rear inclined surface 59 is formed at an angle of 135 ° to 145 °. Since the angle of the front vertical surface 65v is steeper than the angle of the rear inclined surface 59, the direction is not forced. The bottom corner portion 54a and the opening corner portion 54b of the trapezoidal concave dynamic pressure groove 54B are chamfered or formed in a substantially R shape.

  Next, a third modified core pin 60Ac and a third modified resin dynamic pressure bearing member 30Ac molded with the core pin 60Ac will be described with reference to FIG. Each of these is also shown in a sectional view in the same manner as in FIGS.

  The core pin 60Ac in this variation has a partially arcuate protrusion 67C formed on its outer peripheral surface 61, and a base 67b of the partially arcuate protrusion 67C is chamfered or formed in a substantially R shape. It is a type.

  Accordingly, when the core pin 60Ac having such a structure is inserted into the central portion of the movable mold 91 shown in FIGS. 3 and 4, a cavity 92 is formed, and molten resin Mr is injected into the cavity 92 from the gate 85b. The hydrodynamic groove 54C having a partially concave arc-shaped cross section corresponding to the partially arcuate protrusion 67C is transferred to the inner peripheral surface 53 of the cylinder serving as the hydrodynamic bearing member 30Ac. Then, the opening corner 44b of the partially recessed arc-shaped dynamic pressure groove 54C is chamfered or formed in a substantially R shape.

As described above, the protrusion of the core pin 60Ac according to the present modification is a partially arc-shaped protrusion 67C. Accordingly, each of the partially arcuate protrusions 67C and each of the partially recessed arcuate dynamic pressure grooves 54C are not perpendicular surfaces and are not opposed to each other, so that the dynamic pressure bearing member 30Ac can be easily and easily removed from the core pin 60Ac. can do.
It is desirable that the dynamic pressure grooves 54A, 54B, 54C of the dynamic pressure bearing members 30Aa, 30Ab, 30Ac in any form are formed as V-shaped grooves. Each inner peripheral surface 53 is continuously formed on the entire circumference.

  Further, it is desirable that the dynamic pressure grooves 54A, 54B, 54C are formed as continuous grooves having two or more steps at predetermined intervals in the axial direction.

  In the manufacturing method of forming the dynamic pressure grooves 54A, 54B, 54C by injection molding on the inner peripheral surface 53 of the cylindrical dynamic pressure bearing members 30Aa, 60Ab, 60Ac using any of these core pins 60Aa, 60Ab, 60Ac The core pins 60Aa, 60Ab, 60Ac are formed with trapezoidal protrusions 67A, 67B or partially concave arcuate dynamic pressure grooves 54C with inclined surfaces 42, 43 or partially arcuate surfaces with respect to the forcing direction X. In addition, the surface corners 67a of the trapezoidal protrusions 67A and 67B and the base 67b of the trapezoidal protrusions 67B are chamfered or formed in a substantially R shape, and the core pin 60Ac of the third variant is formed. Since the base portion 67b of the partially recessed arc-shaped protrusion 67C is chamfered or formed substantially in an R shape, the core pins 60Aa, 60 thereof are formed. b, when the molten resin is injected and molded into the cavity 92 of the mold into which the 60Ac has been inserted, and the dynamic pressure bearing members 30Aa, 30Ab, 30Ac are forcibly removed after the molding, the forcible removal force is applied to each core pin 60Aa, 60Ab, 60Ac and each of the dynamic pressure bearing members 30Aa, 60Ab, 60Ac escape by sliding, and the dynamic pressure grooves 54A, 54B, 54C of the formed dynamic pressure bearing members 30Aa, 60Ab, 60Ac are damaged. Can be prevented from being deformed.

  As an example of the dimensions of the dynamic pressure bearing members 60A, 60Aa, 60Ab, and 60Ac, the outer diameter of the cylindrical portion 50 is 6.5 mm, the inner diameter is 1.5 mm, and the total length of the dynamic pressure bearing member 30A is 8.6 mm. The length of the cylindrical portion 50 is 4.7 mm, the shape of each of the dynamic pressure grooves Ra and Rb is V-shaped, their width is 1 mm to 1.5 mm, and the distance between the dynamic pressure grooves Ra and Rb is 0 About 6 mm, the depth of the groove is about 0.01 mm, and the depth of the retaining washer engaging groove 57 is about 0.05 mm.

  As a general resin used for a conventional resin dynamic pressure bearing member, in order to achieve the dimensional accuracy required for the dynamic pressure bearing and the rigidity required for the bearing member, a material having a considerably high elastic modulus is used. Need to use. In the dynamic pressure bearing member of the present invention, when the dynamic pressure bearing member 30A or the core pin 60A is forcibly removed, the movable side die 91 is retracted from the molded dynamic pressure bearing member 30A. Since the outer side of the member 30A is a free space, when the radial dynamic pressure grooves Ra and Rb of the core pin 60A and the retaining washer engaging groove forming annular protrusion 64 pass, the cylindrical portion 50 of the dynamic pressure bearing member 30A. Since the force which pushes outward slightly is exerted, the radial dynamic pressure grooves Ra and Rb formed on the inner peripheral surface 53 of the cylindrical portion 50 are hardly damaged and are not easily deformed.

  Further, as described above, the rear surface of the concave portion of the dynamic pressure groove with respect to the forcibly removing direction X of the core pin 60A is formed as an inclined surface, whereby the dynamic pressure bearing member 30A of the first embodiment of the present invention is formed after the molding. Since it can be easily removed from 60A, a highly rigid material can also be used. Examples thereof include polyether ether ketone resin and polyphenylene sulfide resin, as well as polybutylene terephthalate resin and polyethylene terephthalate resin.

  Further, the outer shape of the fluid dynamic bearing members 30A, 30A, 60Ab, 60Ac is usually a cylinder, but in the present invention, it is not limited to a cylinder, depending on the mounting location of the fluid dynamic bearing member, For example, it is added that it can be formed into a square cross section.

  Next, with reference to FIG. 15, a method of mounting the rotating shaft 31 of the motor (FIG. 21) on the dynamic pressure bearing member 30 </ b> A of the first embodiment will be described.

  FIG. 15 is an explanatory view for explaining an assembly process for mounting the rotating shaft on the cylindrical portion of the dynamic pressure bearing member of the present invention. FIG. 15A shows that a retaining washer is mounted on the dynamic pressure bearing member. A cross-sectional view of the both showing the middle, FIG. B is a cross-sectional view of both showing the state where the retaining washer is mounted in the retaining washer engaging groove of the dynamic pressure bearing member, and FIG. It is sectional drawing of the member for dynamic pressure bearings, the prevention washer, and the rotating shaft which showed the state which was inserted and was prevented from falling out.

  First, as shown in FIG. 15A, the retaining washer W is inserted into the bearing hole 51 from the rotary shaft insertion port 51a of the cylindrical portion 50 of the dynamic pressure bearing member 30A of the first embodiment. The material of the retaining washer W is made of a flexible plastic such as nylon, and the diameter thereof is larger than the diameter shape of the bearing hole 51, and is fitted into the retaining washer engaging groove 57, and the rotary shaft 31 is located at the center thereof. Is a disc-shaped one in which a plurality of cuts are made from the hole toward the circumferential edge of the circle. The state shown in the figure shows a state where the retaining washer W is pushed in and is bent downward.

  When further pushed in, as shown in FIG. B, the retaining washer W is fitted into the retaining washer engaging groove 57 and is mounted in the dynamic pressure bearing member 30A.

  When the rotary shaft 31 in which the washer engaging groove 31e is formed on the outer peripheral surface of the tip portion is inserted from the rotary shaft insertion port 51a toward the central hole of the retaining washer W in this state, as shown in FIG. The tip of the rotating shaft 31 passes through the central hole of the retaining washer W, and the edge of the retaining washer W in the central hole is fitted into the washer engaging groove 31e.

  Therefore, the rotating shaft 31 is engaged with the dynamic pressure bearing member 30 </ b> A by the retaining washer W, and the rotating shaft 31 can be prevented from coming out of the rotating shaft hole 51.

  Next, a dynamic pressure bearing member, a molding die thereof, and a manufacturing method thereof according to a second embodiment of the present invention will be described with reference to FIGS.

  16 is a sectional view of a fluid dynamic bearing member according to a second embodiment of the present invention, FIG. 17 is a sectional view of a movable side mold for molding the fluid dynamic bearing member shown in FIG. 16, and FIG. FIG. 19 is a cross-sectional view of a molding die shown in a state in which the movable side die and the fixed side die shown in FIG. 17 are fastened together. FIG. 19 is a diagram showing the molding die shown in FIG. After that, the dynamic pressure bearing member in a state where the movable side mold is opened from the fixed side mold and the sectional view of the molding die, and FIG. 20 shows the state in which the molded dynamic pressure bearing member is forcibly removed from the core pin. It is sectional drawing of the member for dynamic pressure bearings shown, and its molding die.

  In this embodiment, the same reference numerals are given to the same structure and components of the dynamic pressure bearing member and the molding die of the first embodiment of the present invention, and the detailed description is omitted. .

  First, the structure of the fluid dynamic bearing member of the second embodiment of the present invention will be described with reference to FIG. The structure of the dynamic pressure bearing member 30B is in the cylindrical portion 50A. The cylindrical portion 50A is formed in a state in which a cylindrical slit 51S concentric with the rotation shaft hole 51 divides the end surface of the cylindrical portion 50A vertically, and is formed in a double structure of an inner cylindrical portion 50B and an outer cylindrical portion 50C. Yes.

  By adopting a double structure including the cylindrical slit 51S, the rigidity of the inner cylinder part 50B can be reduced, and a free space can be formed on the outer periphery of the inner cylinder part 50B. Therefore, the inner cylinder portion 50B is greatly easily bent.

  The outer cylindrical portion 50C of the double-structured cylindrical portion 50A is unnecessary when the core pin 60A is forcibly removed, so the thickness of the original cylindrical portion 50A may be reduced. For example, as shown in FIG. When used for the bearing unit 30 of such a motor 1, the motor 1 can be manufactured at a lower cost by using the existing core 15. Since the inner diameter of the existing core 15 is standardized, the outer diameter of the outer cylindrical portion 50C needs to be matched with the predetermined outer dimension of the existing core 15. Even when incorporated in an electronic device, the cylindrical portion 50A is easier to handle if it has a certain thickness. Therefore, it is better not to make the cylindrical portion 50A thinner except in special cases.

  Next, the structure of the movable mold 91B used for forming the dynamic pressure bearing member 30B will be described with reference to FIG.

  The movable mold 91B protrudes in a concentric ring shape from the base 61Ba toward the flange cavity 92a side, centering on a through hole 91b for the core pin 60A opened at the center of the base Ba. A cylindrical slit forming protrusion 91S is formed. Therefore, as the cavity 92, an inner cylinder formed between the outer peripheral surface of the flange cavity 7a and the dynamic pressure groove forming portions 62a and 62b of the core pin 60A and the inner peripheral surface side of the cylindrical slit forming protrusion 91S. The portion forming cavity 92b, and the outer peripheral surface of the cylindrical slit forming protrusion 91S and the outer cylindrical portion forming cavity 92c. Since other components and assembly methods are the same as those described with reference to FIG. 3, their descriptions are omitted.

  Next, a molding method for molding the dynamic pressure bearing member 30B using the movable side mold 91B and the fixed side mold 85 will be described.

  First, the parting surface 85c of the fixed side mold 85 and the parting surface 91a of the movable side mold 91B are brought into close contact with each other to form a sealed cavity 92, and a molten resin is formed in the cavity 92 from the gate 85b. Mr is injected and filled. The filled molten resin Mr is injected from the flange portion cavity 7a, and spreads uniformly into the inner tube portion forming cavity 92b and the outer tube portion forming cavity 92c.

  Next, as shown in FIG. 19, when the molten resin Mr is cured, the fastening between the fixed mold 85 and the movable mold 91B is released, and the flange portion 56 of the molded hydrodynamic bearing member 30B is removed. Only the movable mold 91B and the movable mold holder 93 are pressed with the plurality of ejector pins 94 and the coil spring 95 pressed against the parting surface 85c of the fixed mold 85 and without removing the core pin 60A. Is moved backward in the right direction of arrow X.

  Subsequently, as shown in FIG. 20, the entire movable side 90 is slightly retracted from the parting surface 85 c of the fixed side mold 85, but the back surface of the flange portion 56 of the molded hydrodynamic bearing member 30 </ b> B. Is separated from the gate 85b.

  Although not shown in the drawings, as described in the manufacturing process of the dynamic pressure bearing member 30A, the ejector pin 94 and the coil spring 95 remain pressed against the flange portion 56 of the dynamic pressure bearing member 30B. As described above, the core pin 60A is rotated in the Xr direction at a slight rotation angle within one rotation in the direction of the V-shaped tip of each of the radial dynamic pressure grooves Ra and Rb, and forcibly removed in the right direction of the X axis. . When completely removed, the dynamic pressure bearing member 30B having a structure in which the cylindrical portion 50A as shown in FIG. 16 is divided into an inner cylindrical portion 50B and an outer cylindrical portion 50C is obtained.

  Since the core pin 60A is forcibly removed from the thin inner cylinder part 50B as described above, the inner cylinder part 50B is moved when the core pin 60A is forcibly removed as described in the hydrodynamic bearing member 30A of the first embodiment. It becomes easier to expand outward than the cylindrical portion 50A of the pressure bearing member 30A, and when the dynamic pressure groove forming portions 62a, 62b and the retaining washer engaging groove forming annular projection 64 pass, the inner cylindrical portion 50B expands, Can be obtained without damaging or deforming the dynamic pressure grooves Ra and Rb formed on the inner peripheral surface 53 of the bearing hole 51.

  In the description of each of the above-described embodiments, when the core pin 60A is forcibly removed from the dynamic pressure bearing members 30A and 30B of the present invention, the core pin 60A is first moved in the direction of the V-shaped tip of each of the radial dynamic pressure grooves Ra and Rb. Although it has been described that it is rotated by a slight rotation angle within one rotation and forcibly removed in the right direction of the X-axis indicated by the symbol X, the present invention is not limited to such a method for forcibly removing the core pin. When 60A is forcibly removed from the dynamic pressure bearing members 30A and 30B, at least the tip of the core pin 60A is in the radial state between the molded state where the bottom 52 of the dynamic pressure bearing members 30A and 30B is located and the radial dynamic pressure groove Ra. The core pin 60A is forcibly removed in the right direction of the X-axis while being rotated at a slight rotation angle within one rotation in the direction of the V-shaped tip of each of the dynamic pressure grooves Ra and Rb. Keep additional remark that may be so.

  The protruding position of the dynamic pressure bearing member by the ejector pin 94 is not limited to the surface of the flange portion 56, and the opening end face of the dynamic pressure bearing member that is a molded product may be protruded.

  The present invention can be used in the electronic motor industry, the bearing manufacturing industry, and the like.

It is a cross-sectional enlarged view of the member for dynamic pressure bearings of 1st Example of this invention. It is an enlarged side view of the core pin used in order to shape | mold the member for dynamic pressure bearings shown in FIG. FIG. 3 is an enlarged cross-sectional side view of a movable mold in which a core pin and an ejector pin shown in FIG. 2 are assembled. It is sectional drawing of an example of the injection mold comprised from the stationary side metal mold | die and movable side metal mold | die for injection-molding the member for dynamic pressure bearings of this invention, and having represented both. It is sectional drawing of the state which opened the injection die shown in FIG. FIG. 6 is a cross-sectional view showing an operation subsequent to the operation shown in FIG. 5 and showing a state where the hardened dynamic pressure bearing member is released from the parting surface of the fixed side mold. FIG. 7 is a cross-sectional view illustrating an operation subsequent to the operation illustrated in FIG. 6 and illustrating a moment when the core pin of the movable mold and the dynamic pressure bearing member are forcibly removed. FIG. 8 is a cross-sectional view illustrating an operation subsequent to the operation illustrated in FIG. 7, in which the core pin and the dynamic pressure bearing member of the movable mold are completely forcibly removed. FIG. 9 is a cross-sectional view showing the operation following FIG. 8 and showing the relationship between the dynamic pressure bearing member and the injection mold in a state obtained by the method for manufacturing a dynamic pressure bearing member of the present invention. It is explanatory drawing when forcibly extracting a core pin only to the axial direction (X-axis direction) of the member for dynamic pressure bearings, The same figure A is a radial dynamic pressure groove formed in the internal peripheral surface of the member for dynamic pressure bearings FIG. 5B is a development view in which the development view of the protrusions formed on the outer peripheral surface of the core pin is superimposed on the development view of the radial dynamic pressure groove in FIG. It is explanatory drawing at the time of rotating a core pin slightly and forcibly removing in the axial direction of the member for dynamic pressure bearings, The figure A is radial dynamic pressure formed in the internal peripheral surface of the member for dynamic pressure bearings FIG. 7B is a development view in which a development view of the protrusion formed on the outer peripheral surface of the core pin is superimposed on the development view of the radial dynamic pressure groove in FIG. It is sectional drawing which showed a part of core member of the 1st modification of the 1st example suitable for use in the present invention, and a member for hydrodynamic bearings of the 1st modification formed with this core pin. It is sectional drawing which showed a part of core member of the 2nd modification of 1st Example suitable for use in this invention, and the member for dynamic pressure bearings of the 2nd modification shape | molded with this core pin. It is sectional drawing which showed a part of core member of the 3rd modification suitable for use in this invention, and the member for dynamic pressure bearings of the 3rd modification shape | molded with this core pin. BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing for demonstrating the assembly process which mounts a rotating shaft to the cylinder part of the member for dynamic pressure bearings of this invention, Comprising: The same figure A shows the middle of mounting | wearing with the retaining washer to the member for dynamic pressure bearings. FIG. 4B is a sectional view showing the state where the retaining washer is mounted in the retaining washer engaging groove of the dynamic pressure bearing member, and FIG. It is sectional drawing of the member for dynamic pressure bearings, the prevention washer, and the rotating shaft which showed the state with which prevention was carried out. It is sectional drawing of the member for dynamic pressure bearings of 2nd Example of this invention. It is sectional drawing of the movable side metal mold | die for shape | molding the member for dynamic pressure bearings shown in FIG. It is sectional drawing of the shaping die shown in the state which fastened the movable side metal mold | die shown in FIG. 17, and the fixed side metal mold | die. FIG. 18 is a cross-sectional view of a dynamic pressure bearing member in a state in which the movable side mold is opened from the fixed side mold after the dynamic pressure bearing member of the present invention is molded with the molding die shown in FIG. 18. is there. It is sectional drawing of the member for dynamic pressure bearings which showed the state which forcibly removes the member for dynamic pressure bearings shape | molded from the core pin, and its molding die. It is sectional drawing of the small motor of an example used for the small electronic device. It is a cross-sectional side view of the bearing unit of the 1st form which can be used for the motor shown in FIG. It is a cross-sectional perspective view of the member for dynamic pressure bearings integrated in the bearing unit shown in FIG. It is a cross-sectional side view of the bearing unit of the 2nd form which can be used for the motor shown in FIG. The prior art hydrodynamic bearing member that can be incorporated into the bearing unit of the third embodiment is shown. FIG. A is a sectional side view thereof, and FIG. B is a partially enlarged view of FIG. The core pin of the 1st example used when carrying out injection molding of the member for hydrodynamic bearings of the 3rd form is shown, The figure A is the side view, The figure B is the expanded sectional view of the principal part. It is principal part sectional drawing which showed an example of the injection mold for injection molding using the core pin shown in FIG. FIG. 28 is a cross-sectional view of the partial injection molding die and the dynamic pressure bearing member shown in FIG. 27 for illustrating a method of releasing the dynamic pressure bearing member molded by the injection molding die shown in FIG. 27. It is an expanded sectional view of the principal part of the core pin of the 3rd example of conventional technology. It is an expanded sectional view of the principal part of the member for dynamic pressure bearings of the 2nd example injection-molded using the core pin of FIG.

Explanation of symbols

30A ... Dynamic pressure bearing member of the first embodiment of the present invention, 30Aa ... Dynamic pressure bearing member of the first modified form, 30Ab ... Dynamic pressure bearing member of the second modified form, 30Ac ... Dynamic of the third modified form Pressure bearing components,
30B ... Dynamic pressure bearing member according to the second embodiment of the present invention, 50, 50A ... cylindrical portion, 50B ... inner peripheral cylindrical portion, 50C ... outer peripheral cylindrical portion, 51 ... bearing hole, 51a ... rotary shaft insertion port, 51S ... Circular slit, 52 ... bottom part, 53 ... inner peripheral surface of bearing hole 51, 54 ... dynamic pressure groove, 55 ... land part, 56 ... flange part, 57 ... retaining washer engaging groove, 60A ... core pin, 61 ... core pin 60A Outer peripheral surface, 62a, 62b ... dynamic pressure groove forming portion, 63A ... thrust bearing forming portion, 64 ... retaining washer engaging groove forming annular projection, 80 ... fixed side, 85 ... fixed side mold, 85b ... gate, 85c ... fixed Parting surface of side mold 85, 90 ... movable side of the present invention, 91 ... movable side mold of the first embodiment of the present invention, 91a ... parting surface of movable side mold 91, 92 ... cavity, 92a ... Flange cavity, 92b ... Cylinder Cavity (inner cylinder forming cavity), 92c ... outer cylinder forming cavity, 93 ... movable mold holder, 94 ... ejector pin, R ... radial bearing, Ra, Rb ... dynamic pressure constituting the radial bearing R Groove, S ... Thrust bearing, W ... Stop washer

Claims (32)

  The circular hole in the cylindrical portion has a predetermined length, and is formed of a bottomed resin cylindrical portion in which a circular cross section is inserted into which the rotary shaft is inserted, and one end is opened as a rotary shaft insertion port. A dynamic hydrodynamic groove having a predetermined shape is integrally formed on the inner peripheral surface, a thrust bearing portion is integrally formed on the bottom portion, and a retaining washer engaging groove is integrally formed above the thrust bearing portion. Pressure bearing member. The circular slit having a predetermined length that opens on an end surface of the resin cylindrical portion on the rotating shaft insertion port side is formed in the axial direction of the circular hole and concentrically. The member for a hydrodynamic bearing as described.   The dynamic pressure bearing member according to claim 1, wherein a flange portion is integrally formed outside the thrust bearing portion of the cylindrical portion.   3. The dynamic pressure bearing member according to claim 1, wherein the thrust bearing portion is formed as a part of a sphere.   The dynamic pressure bearing member according to claim 2, wherein the circular slit is formed to extend to the thrust bearing portion.   The dynamic pressure bearing member according to claim 1, wherein two or more stages of dynamic pressure grooves are formed in the axial direction on the inner peripheral surface of the cylindrical portion.   The dynamic pressure bearing member according to claim 1, wherein the dynamic pressure groove is formed by a continuous V-shaped groove.   The dynamic pressure bearing member is formed by resin injection molding, and when the dynamic pressure bearing member is forcibly removed from the injection mold, the cross-sectional shape of the dynamic pressure groove in the direction of forced removal is formed in a trapezoidal concave shape. And the angle of inclination of at least the rear inclined surface in the direction of forced removal of the trapezoidal concave is formed from 135 ° to 150 °, and the bottom corner and the opening corner of the dynamic pressure groove are chamfered or substantially 8. The dynamic pressure bearing member according to claim 1, wherein the member is formed in an R shape.   The dynamic pressure bearing member is formed by resin injection molding, and when the dynamic pressure bearing member is forcibly removed from the injection mold, the sectional shape of the dynamic pressure groove in the direction of forced removal is formed in an arcuate concave surface. The dynamic pressure bearing member according to claim 1, wherein the dynamic pressure bearing member is provided. A bearing hole having a predetermined length and having a circular inner cross-section into which the rotary shaft is inserted is formed, and one end is opened as a rotary shaft insertion port. A member for a hydrodynamic bearing in which a radial dynamic pressure groove having a predetermined shape is formed on the inner peripheral surface of the hole, a thrust bearing portion is integrally formed on the bottom, and a retaining washer engagement groove is integrally formed above the thrust bearing portion. An injection mold for molding
A core pin that forms the bearing hole, the radial dynamic pressure groove, a thrust bearing portion, and a retaining washer engaging groove;
A fixed mold for forming the cylindrical portion;
A movable mold for forming the cylindrical portion;
The mold for injection molding characterized in that the movable side mold and the core pin can be individually moved in the same direction, and the core pin can be rotated as necessary. Type. A bearing hole having a predetermined length and having a circular inner cross-section into which the rotary shaft is inserted is formed, and one end is opened as a rotary shaft insertion port. A member for a hydrodynamic bearing in which a radial dynamic pressure groove having a predetermined shape is formed on the inner peripheral surface of the hole, a thrust bearing portion is integrally formed on the bottom, and a retaining washer engagement groove is integrally formed above the thrust bearing portion. An injection mold for molding
A protrusion having a predetermined shape for forming the radial dynamic pressure groove of the dynamic pressure bearing member on the outer peripheral surface, and a retaining for forming the retaining washer engaging groove of the dynamic pressure bearing member on the tip side. A core pin having a washer-engaging groove forming protrusion and a thrust bearing forming portion for forming the thrust bearing portion of the dynamic pressure bearing member on a tip end surface thereof is provided. Injection mold. The circular hole in the cylindrical portion has a predetermined length, and is formed of a bottomed resin cylindrical portion in which a circular cross section is inserted into which the rotary shaft is inserted, and one end is opened as a rotary shaft insertion port. A radial dynamic pressure groove having a predetermined shape is formed on the inner peripheral surface, a thrust bearing portion is integrally formed on the bottom portion, and a retaining washer engagement groove is integrally formed above the thrust bearing portion. An injection mold for molding a dynamic pressure bearing member formed concentrically with a circular slit having a predetermined length opening in an end face of the resin cylindrical portion on the mouth side in the axial direction of the circular hole Because
A protrusion having a predetermined shape for forming the radial dynamic pressure groove of the dynamic pressure bearing member on the outer peripheral surface, and a retaining for forming the retaining washer engaging groove of the dynamic pressure bearing member on the tip side. A core pin in which a washer engagement groove forming protrusion and a thrust bearing molding portion for forming the thrust bearing portion of the dynamic pressure bearing member on the tip surface are formed;
A cylindrical projection for forming the cylindrical portion having an inner circumferential surface having a circular cross section that forms a cylindrical portion cavity forming the cylindrical portion and a cavity forming the thrust bearing forming portion continuous with the cylindrical portion cavity; A mold for injection molding, comprising: a movable mold in which a cylindrical projection that concentrically forms the circular slit is formed in the middle of the cylindrical projection.   13. The taper surface or R shape which becomes low in the said cylinder part side of the said protrusion washer engaging groove formation protrusion formed in the front-end | tip part vicinity of the said core pin is characterized by the above-mentioned. Mold for injection molding.   The injection mold according to claim 11 or 12, wherein the protrusions on the outer peripheral surface of the core pin are formed in two or more stages with a predetermined interval in the axial direction thereof.   The injection mold according to claim 11 or 12, wherein the protrusion on the outer peripheral surface of the core pin is a continuous V-shaped protrusion.   The mold for injection molding according to claim 11 or 12, wherein corners of the protrusions formed on the outer peripheral surface of the core pin are chamfered.   The cross-sectional shape of the protrusion formed on the outer peripheral surface of the core pin is an acute angle with respect to the direction in which the dynamic pressure bearing member is forcibly pulled out, and with respect to the outer peripheral surface of the core pin, and the acute angle is 30 ° to 45 °. 13. The injection mold according to claim 11 or 12, wherein the protrusions are formed at an angle of.   A cross-sectional shape corresponding to the shape of the dynamic pressure groove is formed on the outer peripheral surface of the core pin by a trapezoidal protrusion, and an inclination angle of at least a rear slope in the forcibly removing direction of the trapezoidal protrusion is the outer periphery of the core pin. An acute angle with respect to the surface, the acute angle being formed at an angle of 30 ° to 45 °, and the surface corner of each trapezoidal protrusion and the base of each trapezoidal protrusion are chamfered or substantially R-shaped. The injection mold according to claim 11 or 12, wherein the injection mold is formed.   A cross-sectional shape corresponding to the shape of the dynamic pressure groove is formed on the outer peripheral surface of the core pin by a partially arc-shaped protrusion, and a base portion of the partially arc-shaped protrusion is chamfered or formed substantially in an R shape. The injection mold according to claim 11 or 12, wherein the mold is an injection mold. The circular hole in the cylindrical portion has a predetermined length, and is formed of a bottomed resin cylindrical portion in which a circular cross section is inserted into which the rotary shaft is inserted, and one end is opened as a rotary shaft insertion port. A dynamic pressure bearing member in which a radial dynamic pressure groove having a predetermined shape is formed on the inner peripheral surface of the shaft, a thrust bearing portion is integrally formed on the bottom, and a retaining washer engagement groove is integrally formed above the thrust bearing portion. In manufacturing by injection molding,
A molten resin injection gate is formed facing the parting surface, and a fixed mold,
A fluid pressure bearing member to be formed with a through hole having a circular cross-section penetrating the parting surface and having a parting surface capable of moving forward and backward with respect to the fixed-side mold and closely contacting the parting surface. A movable mold in which a cavity forming at least a part is formed;
A protrusion having a predetermined shape for forming the radial dynamic pressure groove of the dynamic pressure bearing member on the outer peripheral surface of the movable side mold with a thickness that can be inserted into the through hole of the movable side mold. A stopper washer engaging groove forming projection for forming the stopper washer engaging groove of the dynamic pressure bearing member on the tip end side, and the thrust bearing portion of the fluid dynamic bearing member on the tip surface. The thrust bearing molding part is formed and can be moved in the same direction as the movement of the movable mold, but using an injection mold configured with an individually moving core pin,
With the core pin inserted into a predetermined position in the through-hole of the movable mold, the parting surface of the movable mold is abutted and brought into close contact with the parting surface of the fixed mold. Conclude,
Injecting and filling molten resin from the molten resin injection gate into a cavity formed by the fixed side mold and the movable side mold,
After the injection injection and the filled molten resin is cured, the fastening between the fixed side mold and the movable side mold is released,
Retreating the movable side mold from the parting surface of the fixed side mold and the outer peripheral surface of the cured dynamic pressure bearing member;
Thereafter, the core pin from the dynamic pressure bearing member or the core pin from the dynamic pressure bearing member to the dynamic pressure bearing in a state where the movable die is not present around the cured dynamic pressure bearing member. A method for producing a fluid dynamic bearing member, wherein the fluid dynamic bearing member is obtained by forcibly removing the member in the axial direction. The circular hole in the cylindrical portion has a predetermined length, and is formed of a bottomed resin cylindrical portion in which a circular cross section is inserted into which the rotary shaft is inserted, and one end is opened as a rotary shaft insertion port. A radial dynamic pressure groove having a predetermined shape is formed on the inner peripheral surface, a thrust bearing portion is integrally formed on the bottom portion, and a retaining washer engagement groove is integrally formed above the thrust bearing portion. In manufacturing a hydrodynamic bearing member formed concentrically with a circular slit having a predetermined length opening in the end surface of the resin cylindrical portion on the mouth side in the axial direction of the circular hole,
A molten resin injection gate is formed facing the parting surface, and a fixed mold,
A cylindrical part cavity that includes a parting surface that can be moved forward and backward relative to the stationary mold and that can be in close contact with the parting surface, and that forms at least the cylindrical part of a member for a hydrodynamic bearing to be molded, and the cylinder The cylindrical projection for forming the cylindrical portion having an inner circumferential surface having a circular cross section that forms a cavity forming the thrust bearing molding portion continuously with the portion cavity, and the circular slit concentrically between the cylindrical projections A movable side mold formed with a cylindrical projection forming
Protruding strips of a predetermined shape for forming a dynamic pressure groove on the outer peripheral surface of the movable side mold with a thickness that can be inserted into the through-hole of the movable side mold are formed on the outer periphery around the tip portion. The retaining washer engaging groove forming projection and the thrust bearing forming portion are formed on the tip surface thereof, and move in the same direction as the movement of the movable mold, or the movement of the movable mold Using an injection mold that can move in the same direction but is configured with a core pin that moves individually,
With the core pin inserted into a predetermined position in the through-hole of the movable mold, the parting surface of the movable mold is abutted and brought into close contact with the parting surface of the fixed mold. Conclude,
Injecting and filling molten resin from the molten resin injection gate into the cavity formed by the fixed side mold and the movable side mold,
After the injection injection and the filled molten resin is cured, the fastening between the stationary mold and the movable mold is released,
Forcibly removing the movable side mold from the dynamic pressure bearing member in the axial direction of the dynamic pressure bearing member from the parting surface of the fixed side mold and the outer peripheral surface of the cured dynamic pressure bearing member, A method for producing a fluid dynamic bearing member, comprising: obtaining the fluid dynamic bearing member.   The method of manufacturing a dynamic pressure bearing member according to claim 20 or 21, wherein the core pin is rotated and the core pin is forcibly removed in an axial direction of the dynamic pressure bearing member.   The member for a hydrodynamic bearing according to claim 20 or 21, wherein the protrusions on the outer peripheral surface of the core pin are formed in two or more stages at predetermined intervals in the axial direction thereof. Method.   24. The method for manufacturing a fluid dynamic bearing member according to claim 20, wherein the protrusions on the outer peripheral surface of the core pin are continuous V-shaped protrusions.   The method for manufacturing a member for a hydrodynamic bearing according to claim 24, wherein a turning direction of the core pin is a pointed direction of the V-shaped protrusion.   When the core pin is forcibly removed in the axial direction of the dynamic pressure bearing member in which two or more stages of dynamic pressure grooves are formed on the inner peripheral surface of the cylindrical portion, the angle at which the core pin is rotated is forcibly removed. 25. The method for manufacturing a member for a hydrodynamic bearing according to claim 22, wherein the angle is such that a series of protrusions of the core pin do not fit into the adjacent dynamic pressure grooves in the axial direction.   The method for manufacturing a member for a hydrodynamic bearing according to claim 20 or 21, wherein the corners of the protrusions formed on the outer peripheral surface of the core pin are chamfered.   The cross-sectional shape of the protrusion formed on the outer peripheral surface of the core pin is an acute angle with respect to the direction in which the dynamic pressure bearing member is forcibly pulled out, and with respect to the outer peripheral surface of the core pin, and the acute angle is 30 ° to 45 °. The method for manufacturing a member for a hydrodynamic bearing according to claim 20 or 21, wherein the protrusions are formed at an angle of.   A cross-sectional shape corresponding to the shape of the dynamic pressure groove is formed on the outer peripheral surface of the core pin by a trapezoidal protrusion, and an inclination angle of at least a rear slope in the forcibly removing direction of the trapezoidal protrusion is the outer periphery of the core pin. An acute angle with respect to the surface, the acute angle being formed at an angle of 30 ° to 45 °, and the surface corner of each trapezoidal protrusion and the base of each trapezoidal protrusion are chamfered or substantially R-shaped. The method for manufacturing a member for a hydrodynamic bearing according to claim 20 or 21, wherein the member is formed.   A cross-sectional shape corresponding to the shape of the dynamic pressure groove is formed on the outer peripheral surface of the core pin by a partially arc-shaped protrusion, and a base portion of the partially arc-shaped protrusion is chamfered or formed substantially in an R shape. The method for producing a member for a hydrodynamic bearing according to claim 20 or 21, wherein:   The hydrodynamic bearing according to claim 20 or 21, wherein the protrusions of the core pin are formed such that protrusions having a V shape are continuous around the outer peripheral surface. Manufacturing method of member. It has a predetermined length, and is formed of a bottomed resin cylinder part with a circular hole in the inside section into which the rotation shaft for the rotating device is inserted, and one end opened as a rotation axis insertion port. A hydrodynamic bearing in which a radial dynamic pressure groove having a predetermined shape is formed on an inner peripheral surface of the circular hole, a thrust bearing portion is integrally formed on the bottom, and a retaining washer engagement groove is integrally formed near the upper portion of the thrust bearing portion. Members for
A rotation shaft insertion hole having a diameter that can be inserted into the retaining washer engaging groove and capable of inserting the rotation shaft at the center is formed, and a plurality of radial rotation holes are formed radially from the rotation shaft insertion hole toward the periphery. A plastic disc-shaped retaining washer with a thickness that cuts and bends,
The rotary shaft for a rotating device in which an end face supported by the thrust bearing portion, an outer peripheral surface supported by the radial bearing portion, and a retaining washer engaging groove are formed in the outer peripheral surface near the end surface And
The retaining washer is bent and inserted from the rotary shaft insertion port of the dynamic pressure bearing member, and the outer peripheral edge of the retaining washer is fitted into the retaining washer engaging groove,
The rotation shaft is inserted into the rotation shaft insertion hole of the retaining washer from the rotation shaft insertion port, and the inner peripheral edge of the rotation shaft insertion hole of the retaining washer is fitted into the retaining washer engaging groove of the rotation shaft. The rotary shaft is configured so that the rotating shaft does not come off from the member for the dynamic pressure bearing.

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