JP4745835B2 - Manufacturing method and type of hydrodynamic bearing - Google Patents

Description

  The present invention relates to a method for manufacturing a dynamic pressure bearing and a die for forming a dynamic pressure bearing. In particular, the present invention relates to a manufacturing method and a mold of a dynamic pressure generating groove which is a main structure of a dynamic pressure bearing.

  A dynamic pressure bearing using the dynamic pressure of a lubricating fluid such as oil or air has a dynamic pressure generating groove on the surface of a shaft or sleeve constituting the bearing. The dynamic pressure generating groove is a fine groove having a width and a depth of about several μm to several tens of μm, and it is required to process this with high accuracy and simplicity.

  Conventionally, techniques such as rolling, etching, and electrolytic processing have been used for processing the dynamic pressure generating groove.

  For example, in the rolling process, as shown in Patent Document 1, there is a method of rolling by rolling a ball-shaped tool on the sleeve inner peripheral surface.

  Moreover, in the etching process, as shown in Patent Document 2, a method by photolithography using a photosensitive resin (photoresist) can be mentioned.

Moreover, in the electrolytic processing, as shown in Patent Document 3, there is a method in which a masking member is disposed between the workpiece and the electrode tool, and the shape provided on the masking member is transferred to the workpiece.
Japanese Patent Laid-Open No. 11-342441 FIG. 8 (c) JP-A-2-34796 JP 2003-39250 A

  In the processing of the dynamic pressure generating groove by the conventional method shown in Patent Document 1, the bulge occurs in the vicinity of the dynamic pressure generating groove due to flesh escape. Cutting is generally used to remove the bulge, but the manufacturing cost increases because the number of steps increases.

  In the processing of the dynamic pressure generating groove by the conventional method shown in Patent Document 2, after the photosensitive resin is applied, exposed and developed, the workpiece is etched and the photosensitive resin is removed. This is a technique capable of controlling the shape of the dynamic pressure generating groove with high accuracy, but requires a large number of processes and increases the manufacturing cost.

  In the processing of the dynamic pressure generating groove by the conventional method shown in Patent Document 3, high-precision processing is realized by a relatively simple method, but it is difficult to process the dynamic pressure generating groove on the surface of a cylinder or a cylinder. is there. Further, since electrolytic processing is used, the workpiece needs to be a conductor, and the material is limited. Further, it is necessary to position the masking member and the machining electrode with respect to the workpiece, and a simpler method is required.

  As described above, there is a need for a technique for manufacturing a dynamic pressure generating groove with high accuracy and low cost for a workpiece having various shapes and materials with a simple configuration.

  In order to solve the above-described problems, in the present invention, a workpiece, which is a material of a shaft or sleeve used for a hydrodynamic bearing, and a mold having a groove are closely attached so that the surface of the workpiece covers the groove, The shape of the groove is transferred to the workpiece by flowing an etchant for etching the workpiece into a space surrounded by the workpiece.

  Moreover, in this invention, you may provide the communicating hole which connects the surface and groove | channel which a type | mold does not contact | adhere closely to a workpiece inside a type | mold.

  In the present invention, the mold has a columnar shape, the workpiece has a cylindrical shape, and the mold is inserted into the workpiece, whereby the mold and the workpiece can be in close contact with each other.

  Moreover, in this invention, you may provide the cavity which opens to the surface where the said type | mold does not contact | adhere to the said workpiece inside a type | mold.

  Moreover, in this invention, a type | mold can be expanded by pressurizing said cavity using gas or a liquid.

  In the present invention, the mold can be reduced by reducing the pressure in the cavity.

  In the present invention, the mold has a cylindrical shape, the workpiece has a columnar shape, and the workpiece is inserted into the mold, whereby the mold and the workpiece can be brought into close contact with each other.

  In the present invention, the mold may be made of resin.

  As described above, according to the present invention, a dynamic pressure generating groove having the same width as that of the groove provided in the mold can be easily formed. Can be controlled with high accuracy.

  Further, since the dynamic pressure generating groove can be processed with a small number of steps, the dynamic pressure bearing can be manufactured at a low cost.

  Further, by providing the communication hole, the distance that the etchant flows while etching the workpiece can be shortened, and the deterioration of the etchant can be reduced. Thereby, processing accuracy can be improved. Further, since the flow and concentration of etching can be controlled relatively freely, the degree of freedom in processing is improved, and a higher performance dynamic pressure generating groove can be manufactured.

  Moreover, the adhesiveness of a type | mold and a workpiece can be improved by expanding a type | mold by the pressurization to a cavity. Thereby, the width of the dynamic pressure generating groove can be controlled with high accuracy.

  Moreover, the mold release property between the mold and the workpiece can be improved by reducing the mold by reducing the pressure in the cavity. Thereby, a dynamic pressure bearing can be manufactured efficiently.

  Further, since the mold can be reused, the dynamic pressure generating groove and the dynamic pressure bearing can be manufactured at low cost.

  Further, since the mold is made of resin, it can be easily duplicated by transfer processing from the original mold. Thereby, the dynamic pressure generating groove and the dynamic pressure bearing can be manufactured at low cost.

The best mode for carrying out the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 1 is a view showing a configuration of a sleeve 100 of a hydrodynamic bearing according to Embodiment 1 of the present invention. FIG. 1A is a top view, and FIG. 1B is a sectional view from the front.

  The sleeve 100 has a cylindrical shape, and a shaft (not shown) is rotatably inserted into the center hole thereof to constitute a hydrodynamic bearing. The sleeve 100 is made of a material such as stainless steel or copper. A plurality of dynamic pressure generating grooves 102 are arranged at equal intervals on the inner peripheral surface 101 of the sleeve 100 having the center hole. The dynamic pressure generating groove 102 has a so-called herringbone shape. The dynamic pressure generating groove 102 shown in FIG. 1 has a shape in which two pairs of herringbone-shaped grooves are connected by straight grooves.

  FIG. 2 is a diagram showing a configuration of a mold 200 according to the first embodiment of the present invention. 2A is a top view and FIG. 2B is a front view.

  Since the mold 200 has a cylindrical shape and has substantially the same diameter as the inner peripheral surface 101 of the sleeve 100, the mold 200 can be inserted into the central hole of the sleeve 100. The mold 200 is made of a resin such as PDMS (polydimethylsiloxane). The mold 200 has an outer peripheral surface 201, and a plurality of grooves 202 are arranged on the outer peripheral surface 201 at equal intervals. The groove 202 has a shape corresponding to the dynamic pressure generating groove 102. The groove 202 has an inlet 202a at one end of the mold 200 and an outlet 202b at the opposite end. A cavity 203 communicating with the upper part of the mold 200 is formed inside the mold 200.

  FIG. 3 is a step diagram showing a method of manufacturing the dynamic pressure bearing sleeve 100 according to the first embodiment of the present invention. In this figure, for convenience of explanation, a part of the sleeve 100 and the mold 200 is cut out.

  In FIG. 3 step S301, a part of the mold 200 having the groove 202 is shown. In step S302, a workpiece 100 'having a center hole is prepared, and the mold 200 is inserted into the center hole of the workpiece 100'. Since the diameter of the center hole of the workpiece 100 ′ and the diameter of the mold 200 are substantially the same, the center hole of the workpiece 100 ′ and the mold 200 are arranged in close contact with each other. Further, the cavity 203 is pressurized with gas or liquid, and the mold 200 is expanded, so that the center hole of the workpiece 100 ′ and the mold 200 are further adhered. In step S303, the etchant (not shown) that flows in from the inflow port 202a flows in the groove 202 from the A direction in the drawing to the B direction in the drawing, and flows out from the outflow port 202b. At this time, the etchant is etched in contact with the workpiece 100 ′ at the groove 202, thereby forming the dynamic pressure generating groove 102 in a shape along the groove 202. In step S304, the pressurization to the cavity 203 is stopped and the mold 200 is removed. Through these series of steps, the dynamic pressure generating groove 102 can be formed on the inner peripheral surface 101 of the sleeve 100.

  In the present embodiment, it is possible to easily form the dynamic pressure generating groove 102 having substantially the same width as the groove 202 provided in the mold 200. By manufacturing the mold 200 with high accuracy, the dynamic pressure generating groove 102 can be formed. The width can be controlled with high accuracy.

  In addition, according to the present embodiment, the dynamic pressure generating groove 102 can be processed with a small number of steps, so that a dynamic pressure bearing can be manufactured at low cost.

  Further, since the mold 200 can be reused, the dynamic pressure generating groove 102 and the dynamic pressure bearing can be manufactured at low cost.

  Further, since the mold 200 is made of resin, it can be easily duplicated by transfer processing from the original mold. Thereby, the dynamic pressure generating groove 102 and the dynamic pressure bearing can be manufactured at low cost.

Further, by expanding the mold 200 by pressurizing the cavity 203, the adhesion between the mold 200 and the workpiece 100 ′ can be improved. Thereby, the width of the dynamic pressure generating groove 102 can be controlled with high accuracy.
(Embodiment 2)
FIG. 4 is a diagram showing a configuration of a mold 400 according to the second embodiment of the present invention. 4A is a cross-sectional view, FIG. 3B is a front view, and FIG. 3C is a bottom view.

  The present embodiment is substantially the same as the manufacturing method described in the first embodiment, but the mold configuration is different.

  The mold 400 has a cylindrical shape, and a plurality of grooves 402 are arranged on the outer peripheral surface 401 at equal intervals. The groove 402 has a shape corresponding to the herringbone type dynamic pressure generating groove. The groove 402 has outlets 402 a and 402 b at the upper and lower ends of the mold 400. Further, a point equidistant from the outlets 402a and 402b on the groove 402 is defined as a vertex 402c of the groove 402 having a herringbone shape. An inflow hole 403 that is a hole that does not penetrate is formed in the lower surface of the mold 400. The mold 400 also has a communication hole 404 that connects the apex 402c and the inlet 403. A plurality of communication holes 404 are provided corresponding to the plurality of grooves 402. An etchant (not shown) that has flowed from the inflow hole 403 passes through the communication hole 404 and reaches the apex 402 c on the groove 402. Further, the etchant passes through the groove 402, reaches the outlets 402a and 402b, and is discharged. The point that the workpiece (not shown) in contact with the outer peripheral surface of the mold 400 is etched while the etchant flows in the groove 402 is the same as in the first embodiment.

  This embodiment also has the effects described in the first embodiment.

Further, according to the present embodiment, the etchant flows into the groove 402 from the apex 402c on the groove 402 and flows out from the outlets 402a and 402b, so that the distance that the etchant flows while etching the workpiece is shortened. And deterioration of the etchant can be reduced. Thereby, processing accuracy can be improved.
(Embodiment 3)
FIG. 5 is a diagram showing a method of manufacturing a dynamic pressure bearing sleeve 500 according to Embodiment 3 of the present invention.

  The present embodiment is substantially the same as the manufacturing method described in the first embodiment, but the mold configuration is different. In addition, in this Embodiment, about the structure same as Embodiment 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

The mold 200 has a density adjustment hole 501 communicating with the groove 202. The density adjustment hole 501 is connected to the outside of the mold 200. FIG. 5A is a diagram corresponding to step S302 in FIG. 3 in the first embodiment. The workpiece 100 ′ and the mold 200 are arranged in close contact with each other, and an etchant (not shown) introduced from an inflow port (not shown) flows in the groove 202. At this time, a concentration adjusting solution for adjusting the concentration of the etchant is introduced from the concentration adjusting hole 501, and the etchant concentration downstream from the vicinity of the connecting portion between the concentration adjusting hole 501 and the groove 202 changes.
For example, when water is used as the concentration adjusting liquid, the etchant concentration can be lowered. Further, by using an etchant as the concentration adjusting liquid, it is possible to suppress deterioration of the etchant during flow. FIG. 5B is a diagram corresponding to step S303 in FIG. 3 in the first embodiment. The etchant contacts the workpiece 100 ′ at the groove 202 portion and performs etching to form a dynamic pressure generating groove 502 in a shape along the groove 202. In the vicinity of the connection portion between the concentration adjusting hole 501 and the groove 202, the etchant concentration changes, so that the etching speed changes, and the depth of the dynamic pressure generating groove 502 can be changed.

  As shown in FIG. 6, by providing a plurality of concentration adjusting holes 501, the concentration gradient of the etchant in the groove 202 can be adjusted relatively freely. The dynamic pressure generating groove 602 formed thereby can have a gradient in its depth.

  5 and 6, the density adjusting hole 501 is provided perpendicular to the workpiece 100 ', but may be provided horizontally.

  This embodiment also has the effects described in the first embodiment. Furthermore, the depth of the dynamic pressure generating groove 501 or the dynamic pressure generating groove 601 manufactured according to the present embodiment can be freely adjusted. Furthermore, the dynamic pressure bearing using the sleeve 500 or the sleeve 600 having these can be operated in an ideal dynamic pressure generation state, and thus has excellent starting characteristics, power consumption, impact resistance, and the like.

It is a figure which shows the structure of the sleeve 100 of the fluid dynamic bearing concerning Embodiment 1 of this invention. It is a figure which shows the structure of the type | mold 200 concerning Embodiment 1 of this invention. It is a step figure showing a manufacturing method of sleeve 100 of a fluid dynamic bearing concerning Embodiment 1 of the present invention. It is a figure which shows the structure of the type | mold 400 concerning Embodiment 2 of this invention. It is a figure which shows the manufacturing method of the sleeve 500 of the fluid dynamic bearing concerning Embodiment 3 of this invention. It is a figure which shows the manufacturing method of the sleeve 600 of the dynamic pressure bearing concerning Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Sleeve 101 Inner peripheral surface 102 Dynamic pressure generating groove 200 type 201 Outer peripheral surface 202 Groove 202a Inlet 202b Outlet 400 type 401 Outer peripheral surface 402 Groove 402a, 402b Outlet 402c Apex 403 Inflow hole 404 Communication hole 500 Sleeve 501 Concentration adjustment hole 502 Dynamic pressure generating groove 600 Sleeve 602 Dynamic pressure generating groove

Claims (11)

A method of manufacturing a hydrodynamic bearing using a shaft or sleeve material used for the hydrodynamic bearing as a workpiece,
A mold manufacturing process including a dynamic pressure generating groove and a mold including a cavity for moving the dynamic pressure generating groove in a radial direction of the workpiece, and the workpiece is closely attached to the dynamic pressure generating groove -type contact step of causing said by flowing an etchant for etching the workpiece to said enclosed by the dynamic pressure generating groove and the workpiece space, the object of the groove of the dynamic pressure generating grooves having the same shape and a transfer step of transferring the workpiece only including,
The die contact step includes an expansion step in which a gas or liquid is sealed in the cavity to expand the cavity, and the dynamic pressure generating groove is moved in the radial direction of the workpiece. Manufacturing method.   The method for manufacturing a hydrodynamic bearing according to claim 1, wherein the die contact step includes an insertion step in which the die having a columnar shape is inserted into the workpiece having a cylindrical shape. A method of manufacturing a hydrodynamic bearing using a shaft or sleeve material used for the hydrodynamic bearing as a workpiece,
A mold manufacturing process including a dynamic pressure generating groove and a mold including a cavity for moving the dynamic pressure generating groove in a radial direction of the workpiece, and the workpiece is closely attached to the dynamic pressure generating groove -type contact step of causing said by flowing an etchant for etching the workpiece to said enclosed by the dynamic pressure generating groove and the workpiece space, the object of the groove of the dynamic pressure generating grooves having the same shape Manufacturing of a hydrodynamic bearing , comprising: a transfer step for transferring to a workpiece; and a die detachment step for reducing the die by evacuating the cavity and detaching the die from the workpiece. Method. 4. The mold adhering step includes an expanding step of enclosing a gas or liquid in the cavity to expand the cavity and moving the dynamic pressure generating groove in a radial direction of the workpiece. The manufacturing method of the hydrodynamic bearing as described in 2. 5. The dynamic pressure according to claim 1 , wherein the die contact step includes an insertion step in which the workpiece having a columnar shape is inserted into the die having a cylindrical shape. Manufacturing method of bearing. The mold has a communication hole that communicates with a space surrounded by the dynamic pressure generating groove and the workpiece, and the transfer step uses the concentration adjusting liquid injected through the communication hole to adjust the concentration of the etchant. by adjusting method for hydrodynamic bearing according to any one of claims 1 to 5, characterized in that it has an etching adjustment step of adjusting the depth of the said groove that is transferred to the workpiece. A material for forming a dynamic pressure bearing in which a material of a shaft or sleeve used for a dynamic pressure bearing is a workpiece, and a dynamic pressure generating groove is formed on the workpiece,
A mold having the dynamic pressure generating groove and a cavity for moving the dynamic pressure generating groove in a radial direction of the workpiece;
It said cavity expands the cavity is pressurized by a gas or liquid, for hydrodynamic bearing formation, wherein the dynamic pressure generating grooves and is used in order to close contact with the workpiece Type. A material for forming a dynamic pressure bearing in which a material of a shaft or sleeve used for a dynamic pressure bearing is a workpiece, and a dynamic pressure generating groove is formed on the workpiece,
A mold having the dynamic pressure generating groove and a cavity for moving the dynamic pressure generating groove in a radial direction of the workpiece;
The die for forming a hydrodynamic bearing, wherein the cavity is used for reducing the inside of the cavity by being reduced in pressure and separating the dynamic pressure generating groove from the workpiece. 8. The hydrodynamic bearing formation according to claim 7, wherein the cavity is used to reduce the inside of the cavity by being reduced in pressure and to release the dynamic pressure generating groove from the workpiece. Type. The cavity has a communication hole communicating from the cavity to the dynamic pressure generating groove,
10. The dynamic pressure bearing forming mold according to claim 7, wherein the communication hole is used for introducing a concentration adjusting liquid for adjusting the concentration of the etchant . Mold for hydrodynamic bearing formation according to any one of claims 7 10, the type of the dynamic pressure bearing formation, characterized in that it is made of resin.

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