JPH08103975A - Manufacture of fluid bearing and the same bearing - Google Patents

Abstract

PURPOSE: To obtain a low-cost bearing by accurately processing the inner periphery of a sleeve for forming a fluid bearing or the outer periphery of a shaft without machining. CONSTITUTION: A molding shaft 41 having an accurately finished surface provided in an injection mold is covered with a metal pipe material 3A for forming a sleeve first layer of a fluid bearing. A plastic material for forming a sleeve second layer 3B is injected in the mold to apply an injection molding pressure to the outer periphery of the material 3A, thereby pressing the inner periphery of the material 3A to the shaft 41 by the molding pressure to be molded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to hydrodynamic bearings, and more particularly to
The present invention relates to a fluid bearing manufacturing method and a fluid bearing suitable for a motor used in an optical deflector such as a copying machine or a laser printer.

[0002]

2. Description of the Related Art Conventionally, there is a dynamic pressure air bearing as a fluid bearing generally used as a bearing for machinery.
The dynamic pressure air bearing is used as a means for supporting the shaft or sleeve provided on the rotating body in a non-contact manner with the other sleeve or shaft provided on the fixed side via the air layer and for stable rotation. Has been. Generally, the sleeve and the shaft are made of an iron-based material, and heat treatment is performed to increase the life of the bearing, or the surface is plated to improve wear resistance. Further, a material using a non-metal material such as high hardness ceramics is also known. further,
JP-A-61-36516, JP-A-60-5321
No. 3, JP-A-57-149623, and JP-A-57-22418, a composite type bearing using a combination of a plastic material and a metal material is also known. ing. The composite type bearing as described above uses a plastic material for the sliding surface of the bearing, and the good moldability of the plastic material allows the bearing to be manufactured at low cost. Due to the self-lubricating property, smooth rotation can be obtained even at the start of rotation when the shaft and the sleeve are in contact with each other.

FIG. 13 is a diagram showing the outline of the structure of a conventionally used dynamic pressure air bearing, in which a sleeve 3 is rotatably supported by a shaft 1. The shaft 1 is formed with a dynamic pressure generating groove 1a, and when the shaft 1 and the sleeve 3 rotate relative to each other, the dynamic pressure generating groove 1a causes the shaft 1 to form an air layer in a gap 15 between the shaft 1 and the sleeve 3. The flow associated with No. 1 causes dynamic pressure, and this dynamic pressure prevents direct contact between the shaft 1 and the sleeve 3 and allows smooth rotation.

The dynamic pressure air bearing having the above-mentioned structure is used as a bearing for a portion which supports a rotary polygon mirror of an optical deflector built in a laser printer, a copying machine or the like.
FIG. 3 is a sectional view showing an example of an optical deflector in which a dynamic pressure air bearing is used. This optical polarizer is of a fixed shaft type in which a lower end of a shaft 1 is attached to a housing 2 and a sleeve 3 inserted into the shaft 1 rotates. On the outer peripheral surface of the shaft 1, there is provided a dynamic pressure generating groove 1a that generates a dynamic pressure when the sleeve 3 rotates and acts as a radial bearing. The sleeve 3, the magnet yoke 5 fixed to the sleeve 3 by press fitting or adhesion, and the magnet 6 fixed to the magnet yoke 5 constitute a so-called scanner motor rotor portion for rotating the rotary polygon mirror 11. . A rotary polygon mirror 11 is attached to the rotor portion. The rotating polygon mirror 11 has a hole 11b formed at the center thereof.
Is attached to the outer peripheral surface of the sleeve 3
Mounted on the center flange 20 of the mirror flange 4
Insert the pressure adjusting member 27 into the mirror cap 12
It is attached by screwing and fixing the screw portion 19 of the. At the time of the above attachment, a tool is inserted into the mirror cap fastening groove 26 and the mirror cap 12 is rotated and tightened. Further, the mirror cap 12 is provided with a balance correction groove 14 to adjust the balance during rotation.

An air pool 23 is formed between the upper end of the shaft 1 and the mirror cap 12 for suppressing vibration in the thrust direction (axial direction of the shaft 1). The fine holes 24 communicate the air reservoir 23 with the outside air to promote the damping effect of the air reservoir 23. The damper 22 is provided to support the bottom portion of the sleeve 3 so that the rotor portion and the housing 2 do not come into direct contact with each other when the rotor portion is stationary.

On the other hand, a stator portion which constitutes a part of the scanner motor is provided with a housing 2, a housing adapter 2a fixed to the housing 2 with a screw 18, a shaft 1 and a housing 2 one end of which is fixed to the housing 2 by press fitting or the like. Stator core 7 fixed by screws 17 via stator core fixing studs 8a, circuit board fixing studs 8
It is composed of a circuit board 9 fixed to b with a screw 16, a magnetic detection element 10 such as a Hall element provided on the circuit board 9, and the like. An electromagnetic coil, which is preferably a toroidal coil, is wound around the stator core 7. The magnet 6 incorporated in the scanner motor that rotationally drives the rotary polygon mirror 11 is composed of an inner magnet 6a and an outer magnet 6b which are permanent magnets, and a stator core 7
Are arranged to face each other from inside and outside. Thus, a magnetic attractive force acts between the stator core 7 and the magnet 6, and the attractive force is such that the position where the magnet 6 and the stator core 7 face each other is in the thrust direction of the shaft 1 of the scanner motor (axial direction of the shaft 1). It works so as not to shift to.

That is, the magnet 6 and the stator core 7
And constitute a magnetic thrust bearing, and when the magnet 6 is displaced upward with respect to the stator core 7, the attraction force acts to pull the magnet 6 downward. Further, when the magnet 6 is displaced downward, the magnet 6 is pulled back upward so that the rotor portion is always held at a constant axial position with respect to the shaft 1. The magnetic detection element 10 detects the leakage magnetic flux of the magnet 6,
When the magnet 6 rotates, it is detected whether the N pole or the S pole has passed the position of the magnetic detection element 10. The detection signal of the magnetic detection element 10 is transmitted to a control circuit unit (not shown) through a printed wiring formed on the circuit board 9. The control circuit section determines the direction of the current flowing through the electromagnetic coil wound around each portion of the stator core 7 based on the detection signal. As a result, interaction with the magnet 6 generates torque in the direction in which the rotation of the scanner motor is continued. The magnetic poles of the inner magnet 6a and the magnetic poles of the outer magnet 6b facing each other are arranged to have the same pole.

When the sleeve 3 rotates, the dynamic pressure generating groove 1
By a, the pressure of the air layer around the shaft 1 (the portion of the bearing gap 15) rises, and this pressure constitutes a dynamic pressure air bearing in which the sleeve 3 is supported in a state of floating above the shaft 1.
In the above-mentioned example, the dynamic pressure generating groove 1a is provided on the outer periphery of the shaft 1, but the same effect can be obtained by providing it on the inner wall surface of the sleeve 3.

The air layer in the gap 15 functions to keep the center of rotation of the rotor part constant. For example, if the sleeve 3 is displaced to the right in FIG. 14, the gap 15 is spaced to the right of the shaft 1. It is widened in one direction and narrowed in the left side of the axis 1. As a result, the pressure in the gap 15 increases on the left side of the shaft 1,
On the other hand, the pressure decreases on the right side, causing an imbalance in the pressure on the left and right, so the sleeve 3 is pushed to the right by this pressure difference,
Eventually it will be returned to its original position. A cover (not shown) is fixed to the housing adapter 2a with screws to prevent dust. The cover is made of plastic for cost reduction. Further, in order to further reduce the cost, it is often used without a cover.

In the optical deflector having the above-described structure, the light beam such as the laser beam incident on the reflecting mirror surface 11a of the rotary polygon mirror 11 is reflected here and emitted toward the operated medium such as the photosensitive drum. It When the light beam enters the reflecting mirror surface 11a and the rotary polygon mirror 11 rotates, the reflected light beam is gradually deflected. When the rotation of the rotary polygon mirror 11 advances and the next reflecting mirror surface 11a rotates, the light beam now enters the reflecting mirror surface 11a. Then, the reflected light beam is deflected also on the reflecting mirror surface 11a in the same manner as the previous reflecting mirror surface 11a. Therefore, the reflected light beam scans a range of a certain angle, and its scanning speed depends on the rotation speed of the rotary polygon mirror 11. The dynamic pressure air bearing used in the optical deflector is a fixed shaft type, but the sleeve 3
There is also known a rotary shaft type in which a rotary shaft is fixed to a housing and a rotary shaft is inserted therein. A conventional technique relating to this type of dynamic pressure air bearing is provided, for example, in Japanese Patent Laid-Open No. 3-199714.

Although the above-mentioned fluid bearing uses the dynamic pressure of air, another fluid bearing is a liquid bearing using a liquid lubricant. FIG. 15 shows an example thereof, and in this example, a bearing 30 made of a permanent magnet is mounted inside the sleeve 3. The shaft 1 is inserted into and supported by the bearing of the sleeve 3. The permanent magnets forming the bearing 30 are magnetized in the radial direction, and are also magnetized in the opposite polarities adjacent to each other in the axial direction of the sleeve 3.
A pair of bearings 30 are arranged above and below in the sleeve 3, and support the shaft above and below at two locations. In the gap between the shaft 1 and the bearing 30,
The magnetic fluid 29 serving as a lubricant is filled. On the other hand, the shaft 1 has a large-diameter shaft portion 1 at a portion thereof facing the bearing 30 of the sleeve 3.
b is formed and the bearings 30 are adjacently magnetized in the opposite directions, the magnetic fluid 29 is held between the bearing 30 and the large-diameter shaft portion 1b, and the upper and lower bearings 30 are The magnetic fluid 29 can also be enclosed in the gap in the axial direction with the shaft 1, and the magnetic fluid 29 is prevented from scattering due to rotation.

Since the axial length of the bearing 30 is longer than the axial length of the large diameter shaft portion 1b, the magnetic flux of the bearing 30 is likely to concentrate on the large diameter shaft portion 1b. Moreover, since the bearings 30 are magnetized so as to be adjacent to each other in the axial direction of the sleeve 3 and opposite in polarity to each other, a larger magnetic attraction force can be obtained than in the case where the bearings 30 are magnetized in one polarity. As a result, the shaft 1 is displaced in the axial direction with respect to the sleeve 3 by the external force, and the large diameter shaft portion 1b
Is moved in the direction away from the bearing 30 facing the bearing 3
It has a structure that can be instantly pulled back by a magnetic force of 0 and can receive a thrust load.

FIG. 16 shows an example in which the liquid bearing having the above structure is used for a scanner motor of an optical deflector, and the large diameter shaft portions 1b, 1b of the shaft 1 have magnetic forces of the upper and lower bearings 30, 30. And the lower end of the shaft 1 is held by the collar 28 of the housing 2.
It is supported by being floated from the upper surface of. The magnetic fluid 29 is filled between the bearing 30 and the shaft 1, and the bearing 3
0 functions as a radial bearing using the magnetic fluid 29 as a lubricant, and also functions as a thrust bearing due to its magnetic attraction. In FIG. 16, 7 is a stator core,
Reference numeral 9 is a circuit board, and 10 is a magnetic detection element such as a Hall element. Further, an air flow separator 31 is provided above the bearing 30 so that the magnetic fluid 29 is not scattered to the outside by the air flow accompanying the rotation.

[0014]

In the fluid bearing as described above, the surfaces of the sleeve and the shaft constituting the bearing are manufactured with extremely high finishing accuracy, and at present, the inner surface of the sleeve and the outer surface of the shaft are The required precision is secured by machining. However, since it is very difficult to perform machining with high precision, the manufacturing cost is high, and as a result, such a fluid bearing cannot be used in a motor or the like aiming at low cost. Therefore, although a bearing having another structure such as a ball bearing is used, the ball bearing and the like have problems such as lack of reliability and noise reduction.

[0015]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to solve the above problems and provide a hydrodynamic bearing which can be manufactured at a low cost without requiring machining and which can obtain high finishing accuracy. Its main purpose is.

[0016]

To achieve the above object, a method of manufacturing a hydrodynamic bearing provided by the present invention is a method of forming a fluid on a molding shaft provided in an injection molding die and having a highly finished surface. A metal pipe material serving as a sleeve of the bearing is covered, and then a plastic material is injected into the injection molding die to apply an injection molding pressure of the plastic material to the outer peripheral surface of the metal pipe material. The inner peripheral surface of the metal pipe material is pressed against the surface of the molding shaft for molding. Also, insert a metal pipe material that will be the shaft of the fluid bearing into the molding hole that has a highly accurate surface provided in the injection mold, and then inject the plastic material into the injection mold. Then, injection molding pressure of a plastic material is applied to the inner peripheral surface of the metal pipe material, and the outer peripheral surface of the metal pipe material is pressed against the surface of the molding hole by the injection molding pressure to mold. is there.

Also, the fluid bearing provided by the present invention is a fluid bearing comprising a sleeve and a shaft, wherein the sleeve has a sleeve first layer having an inner peripheral surface into which the shaft is inserted, and the outer side thereof is substantially concentric. Second sleeve that surrounds
Layer and a sleeve outer diameter layer, the molding shaft having a highly accurate finished surface provided in the injection molding die is covered with the metal pipe material used for the sleeve first layer, and the injection molding die The sleeve outer diameter layer is arranged in a substantially concentric shape with the metal pipe material,
A plastic material is press-fitted from the end surface between the layer and the sleeve outer diameter layer by injection molding to form the sleeve second layer, and the metal used for the sleeve first layer by the injection molding pressure of the plastic material. The pipe material is formed by pressing the inner peripheral surface of the pipe material against the surface of the forming shaft. In this case, the second layer of the sleeve may be composed of a plastic magnet in which magnetic powder is mixed with a plastic material.

[0018]

The metal pipe material forming the sleeve of the fluid dynamic bearing is put on the molding shaft provided in the injection mold, the injection mold is closed, and the plastic material is injected around the metal pipe material. The injection molding pressure acts on the outer peripheral surface of the metal pipe material via the plastic material to press the inner peripheral surface of the metal pipe material against the surface of the molding shaft. The surface of the molding shaft is highly accurately finished, and the inner peripheral surface of the metal pipe material is molded and finished with accuracy close to that of the molding shaft. On the other hand, a metal pipe material that constitutes the shaft of the fluid bearing is inserted into a molding hole provided in an injection molding die, the injection molding die is closed, and a plastic material is injected into the metal pipe material. The injection molding pressure acts on the inner peripheral surface of the metal pipe material via the plastic material, and presses the outer peripheral surface of the metal pipe material against the inner peripheral surface of the molding hole. The inner peripheral surface of the molding hole is finished with high accuracy, and the outer peripheral surface of the shaft is molded and finished with accuracy close to that of the molding hole.

Further, the sleeve 1 made of a metal pipe material whose inner peripheral surface is finished with high precision by the above method.
A fluid bearing that includes a layer, a sleeve outer diameter layer that concentrically surrounds the layer, and a sleeve second layer that is formed of a plastic material is lightweight and highly accurate without requiring machining. Is obtained. Further, when the second layer of the sleeve is made of a plastic magnet, when a magnetic fluid is used as the lubricant, the magnetic attraction force holds the lubricant between the sleeve and the shaft, and the shaft has a thrust direction. It is possible to exert a restoring force on the displacement in the axial direction by applying the suction force of.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an optical deflector in which a dynamic pressure air bearing according to the present invention is used. In the figure, the parts other than the structure of the shaft 1 and the sleeve 3 have the same structure as the optical deflector of FIG. 14 described above. Therefore, these parts will be briefly described, and the parts of the shaft 1 and the sleeve 3 will be described. Only the structure will be described in detail. In FIG. 1, the magnet yoke 5 fixed to the sleeve 3 by press fitting or adhesion, and the magnet 6 including the inner magnet 6a and the outer magnet 6b constitute a rotor portion of the scanner motor, and when the rotor portion rotates, A gap of several μm is generated between the shaft 1 and the sleeve 3, and they rotate without contact. A cross section of the sleeve 3 used in the optical deflector of FIG. 1 is shown in FIG. As shown in the figure, the sleeve 3 includes a sleeve first layer 3A formed of a metal pipe material and a sleeve outer diameter layer 3D, and a sleeve second layer 3B formed of a plastic material such as nylon. And an adhesive layer 3C are interposed to form a laminated structure.

FIG. 3 shows a cross section of the shaft 1 shown in FIG. In FIG. 3, the shaft first layer 1A and the shaft outer diameter layer 1D are formed of a metal pipe material, and the shaft second layer 1B is formed of a plastic material. The same material as the layer 3B is used. Further, the adhesive layer 1C is the shaft second layer 1B and the shaft outer diameter layer 1
It is provided between D and. The inner peripheral surface of the sleeve first layer 3A and the outer peripheral surface of the shaft outer diameter layer 1D are each precisely finished with high smoothness, and a combination of these forms a highly accurate dynamic pressure air bearing.

Next, the sleeve 3 shown in FIGS.
A method of manufacturing the shaft 1 will be described. FIG. 4 schematically shows the structure of an injection mold used in the manufacturing process of the sleeve 3, in which a molding shaft 41 is arranged at the center of a hollow sleeve mold body 40. The surface is smooth and precision finished.

The process of molding the sleeve 3 using the injection molding die constructed as described above will be described.
As shown in the figure, the metal pipe material 3A to be the first layer of the sleeve is covered on the molding shaft, and the metal pipe material 3D to be the outer diameter layer of the sleeve is arranged in the sleeve molding die body 40. That is, the metal pipe material 3 serving as the sleeve first layer 3
A and a pipe member 3D made of metal, which is the outer diameter layer of the sleeve, are set concentrically in the sleeve molding die body 40. In this case, if necessary, an adhesive layer 3C is provided in advance inside the metal pipe material 3D which will be the outer diameter layer of the sleeve.

Next, as shown in FIG. 6, the opening of the sleeve mold main body 40 is closed by the lid mold 42. A communication hole 43 is formed in the lid mold 42, and a molten plastic material 3B serving as a sleeve second layer is formed between the two metal pipe materials by an injection molding machine (not shown) through the communication hole 43. Is pressed into. Due to the injection pressure of the injection molding machine, the plastic material 3B forming the sleeve second layer is formed on the inner surface of the metal pipe material 3D forming the sleeve outer diameter layer and the outer surface of the metal pipe material 3A forming the sleeve first layer. Metal pipe material 3 that applies pressure to form the outer diameter layer of the sleeve
D is pressed against the inner peripheral surface of the sleeve mold body 40,
On the other hand, the inner surface of the metal pipe material 3A serving as the first layer of the sleeve is pressed against the surface of the molding shaft 41. As a result, the inner peripheral surface of the metal pipe material 3A is molded with the highly accurate surface of the molding shaft 41 to obtain a smooth surface. afterwards,
The lid mold 42 is opened to open the sleeve first layer 3A and the sleeve second layer 3A.
The sleeve 3 having the structure shown in FIG. 2 in which the layer 3B, the adhesive layer 3C, and the sleeve outer diameter layer 3D are integrated is obtained. By providing the adhesive layer 3C, the difference between the shrinkage rate of the sleeve second layer 3B after injection and the shrinkage rate of the metal pipe material is absorbed, and the shrinkage of the sleeve second layer 3B causes the sleeve outer diameter layer 3D to move to the sleeve first layer 3D. The first layer 3A is prevented from coming out.

Next, FIG. 7 shows an outline of the structure of an injection molding die used in the manufacturing process of the shaft 1. The shaft molding die body 50 is provided with a molding hole 51. . The inner surface of the molding hole 51 is precisely finished with high precision. Using the injection molding die configured as described above, the shaft 1
First, as shown in FIG. 8, the metal pipe material 1D to be the outer diameter layer of the shaft is formed into the forming hole 51.
The metal pipe material 1A, which is the first shaft layer, is concentrically arranged inside. In this case, an adhesive layer 1C is previously provided on the inner surface of the metal pipe material 1D to be the shaft outer diameter layer, if necessary. Further, the metal pipe material 1A is provided with a support pin or the like at the center of the forming hole 51 of the shaft forming die main body 50, and is inserted into this so as not to move during the injection molding. It is fixed at 50. Then, as shown in FIG. 9, the opening of the shaft forming die main body 50 is closed by the lid die 52. Lid mold 52
A communication hole 53 is formed in the through hole 53, and a molten plastic material 1B to be the second shaft layer is press-fitted between the two metal pipe materials through the communication hole 53 by an injection molding machine (not shown). To be done. The plastic material 1B forming the shaft second layer is pressed against the inner surface of the metal pipe material 1D forming the shaft outer diameter layer and the outer surface of the metal pipe material 1A forming the shaft first layer by the injection pressure of the injection molding machine. The outer surface of the metal pipe material 1D that serves as the outer diameter layer of the shaft is pressed against the inner surface of the molding hole 51 of the molding die body 50, and the smooth outer peripheral surface is formed by the highly accurate table of the molding hole 51. can get. If the strength of the shaft 1 may be small, the shaft first layer 1A may be omitted.

The adhesive layer 1C provided between the shaft second layer 1B and the shaft outer diameter layer 1D is contracted between the metal pipe material and the plastic material, as in the case of manufacturing the sleeve 3. By absorbing the difference in the ratio, the shaft first layer 1A is prevented from coming out from the shaft outer diameter layer 1D due to the contraction of the shaft second layer 1B. After the above molding, the surface of the shaft outer diameter layer 1D is processed into a groove for dynamic pressure generation, and the shaft 1 is completed. The shaft 1 and the sleeve 3 manufactured as described above assemble a dynamic pressure air bearing.

Next, another embodiment of the present invention will be described with reference to FIG. The embodiment of FIG. 10 shows an example of an optical deflector using the liquid bearing of the present invention, and the parts other than the structure of the liquid bearing portion are the same as those of the conventional one shown in FIG. Regarding the structure, in the structure shown in FIG. 10, the shaft 1 and the sleeve 3 forming the bearing 30 are formed in a multi-layer structure as in the structures shown in FIGS. 2 and 3.
The sleeve 3 is provided with two upper and lower portions which are vertically adjacent to each other and are magnetized in opposite directions. The large-diameter shaft portion 1b of the shaft 1 which is opposed to the sleeve 3 is attracted to the lower end portion of the shaft 1. Is slightly floated from the upper surface of the collar 28. Between the sleeve 3 and the large-diameter shaft portion 1b, the magnetic fluid 29 acting as a lubricant is generated by the magnetic field of the magnetized portion of the bearing 30.
And is held between the shaft 1 and the shaft 1.

FIG. 11 shows a sectional structure of the sleeve 3 used in the bearing 30 of FIG.
Is the sleeve first layer 3A, the sleeve second layer 3B, the adhesive layer 3
C, the sleeve outer diameter layer 3D, the sleeve first layer 3A and the sleeve outer diameter layer are formed by a metal pipe material, and the sleeve second layer 3B is a plastic material mixed with magnetic powder. Is formed by. The sleeve second layer 3B is formed with adjacent portions 3E and 3F that are magnetized in opposite directions, and these magnetized portions 3E and 3F are spaced apart in the axial direction of the sleeve second layer 3B. It is installed in two places. The sleeve 3 shown in FIG.
5 can be manufactured by the method shown in FIGS. 5 and 6 using the injection mold shown in FIG. 4, and after the sleeve 3 is molded, the sleeve second layer is magnetized. The parts 3E and 3F are magnetized.

On the other hand, FIG. 12 shows a sectional structure of the shaft 1 used in the bearing 30 of FIG. 10, and is shown in FIGS. 8 and 9 using the injection molding die of FIG. 7 described above. After molding by the method, the outer peripheral surface of the shaft outer diameter layer 1D is cut to form the large diameter shaft portion 1b. In the above-mentioned embodiment, the shaft 1 and the sleeve 3 both have a multi-layered structure in which a layer of a plastic material is sandwiched between them, but one of them is formed by an injection molding method, and the conventional machine is used. It is also possible to combine with the other created by processing. Further, the adhesive layers 1C and 3C provided on the shaft 1 and the sleeve 3 may be omitted if the plastic material portion after molding has a small shrinkage.

When a plastic magnet is used for the sleeve second layer 3B, a magnetic material is used for the metal pipe material forming the sleeve outer diameter layer 3D and the shaft outer diameter layer 1D, and the shaft first layer is used. By using a non-magnetic material for the metal pipe material forming 1A, the magnetic attraction force acting between the sleeve 3 and the shaft 1 can be increased.

[0031]

According to the present invention, the inner peripheral surface or the outer peripheral surface of the metal pipe material forming the sleeve or the shaft of the fluid bearing is
Since the method of pressing by pressing against the molding shaft or the molding hole having a highly accurate finished surface is used, a highly accurate fluid bearing can be easily manufactured. Moreover, the metal pipe material is uniformly pressed from the periphery to the outer peripheral surface or the inner peripheral surface of the molding shaft or the molding hole by the fluid pressure of the plastic material melted in the injection molding die. The pipe material does not have uneven finish or deformation. Therefore, the finishing of the sleeve and the shaft of the fluid dynamic bearing can be efficiently performed with high precision, and a highly precise fluid bearing can be manufactured at a significantly low cost as compared with the conventional machining. .

Further, since the fluid bearing obtained by the present invention uses the plastic material for the second layer of the sleeve, it is possible to reduce the weight and to reduce the power consumption when used as the bearing of the motor. it can. Further, when the sleeve second layer is a plastic magnet in which magnetic powder is mixed with a plastic material, when a magnetic fluid is used as a lubricant, the magnetic attraction force causes
The lubricant can be held between the sleeve and the shaft, the lubricant is prevented from scattering due to the high speed rotation of the shaft, and a good lubrication state can be maintained. Further, it is possible to apply a suction force in the thrust direction to the shaft to apply a restoring force to the displacement in the axial direction.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical deflector to which a fluid bearing according to an embodiment of the present invention is applied.

FIG. 2 is a cross-sectional view showing the structure of the sleeve of the fluid dynamic bearing as one embodiment of the present invention.

FIG. 3 is a sectional view showing a structure of a shaft of a fluid dynamic bearing as one embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a schematic structure of an injection mold for use in molding the sleeve of the fluid dynamic bearing of the present invention.

FIG. 5 is an explanatory view of a process of forming the sleeve of the fluid dynamic bearing of the present invention.

FIG. 6 is an explanatory view of a process of forming a sleeve of the fluid dynamic bearing of the present invention.

FIG. 7 is a cross-sectional view showing a schematic structure of an injection mold for use in molding the shaft of the fluid dynamic bearing of the present invention.

FIG. 8 is an explanatory diagram of a molding process of the shaft of the fluid dynamic bearing of the present invention.

FIG. 9 is an explanatory diagram of a molding process of the shaft of the fluid bearing of the present invention.

FIG. 10 is a sectional view of an optical deflector to which a fluid bearing according to another embodiment of the present invention is applied.

FIG. 11 is a cross-sectional view showing a structure of a sleeve of a fluid bearing as another embodiment of the present invention.

FIG. 12 is a cross-sectional view showing the structure of a shaft of a fluid dynamic bearing as another embodiment of the present invention.

FIG. 13 is a sectional view showing an example of a conventional dynamic pressure air bearing.

FIG. 14 is a sectional view of an optical deflector to which a conventional dynamic pressure air bearing is applied.

FIG. 15 is a cross-sectional view showing an example of a conventional liquid bearing.

FIG. 16 is a sectional view of an optical deflector to which a conventional liquid bearing is applied.

[Explanation of symbols]

1 shaft, 1a dynamic pressure generating groove, 1b large-diameter shaft portion, 1A shaft first layer, 1B shaft second layer, 1C
Adhesive layer, 1D shaft outer diameter layer, 3 sleeves,
3A sleeve first layer, 3B sleeve second layer,
3C adhesive layer, 3D sleeve outer diameter layer, 3E / 3
F magnetizing part, 29 magnetic fluid (lubricant), 40
Sleeve mold body, 41 molding shaft, 42.5
2 lid type, 43/53 communicating hole, 50 axis forming die body, 51 forming hole.

Claims (4)

[Claims] 1. A metal pipe material serving as a sleeve of a fluid bearing is covered on a molding shaft having a highly finished surface provided in an injection molding die, and then a plastic material is placed in the injection molding die. Injecting to apply an injection molding pressure of a plastic material to the outer peripheral surface of the metal pipe material, and pressing the inner peripheral surface of the metal pipe material against the surface of the molding shaft by the injection molding pressure to mold. A method of manufacturing a fluid bearing having the characteristics. 2. A metal pipe material serving as a shaft of a hydrodynamic bearing is inserted into a molding hole provided in the injection molding die and having a highly-accurate surface, and then a plastic-based material is inserted into the injection molding die. Injecting material, applying injection molding pressure of plastic material to the inner peripheral surface of the metal pipe material, and pressing the outer peripheral surface of the metal pipe material against the surface of the molding hole by the injection molding pressure A method for manufacturing a fluid bearing, comprising: 3. A hydrodynamic bearing comprising a sleeve and a shaft, wherein the sleeve has a sleeve first layer having an inner peripheral surface into which the shaft is inserted, and a sleeve second layer and a sleeve surrounding the outside in a substantially concentric shape. Composed of an outer diameter layer,
A metal pipe material used for the first layer of the sleeve is covered on a molding shaft having a highly accurate finished surface provided in the injection molding die, and the injection pipe is substantially concentric with the metal pipe material in the injection molding die. The sleeve outer diameter layer is disposed in the sleeve outer layer, and a plastic material is press-fitted from the end surface between the sleeve first layer and the sleeve outer diameter layer by injection molding to form the sleeve second layer. A fluid bearing characterized by being formed by pressing the inner peripheral surface of the metal pipe material used for the first layer of the sleeve against the surface of the molding shaft by the injection molding pressure according to. 4. The fluid bearing according to claim 3, wherein the second sleeve layer is a plastic magnet in which magnetic powder is mixed with a plastic material.