JPS61262221A - Dynamic pressure fluid bearing device - Google Patents

Abstract

PURPOSE:To prevent a thrust seat member from accelerative wear, by projecting the end surface of the first material member from that of the second material member to a predetermined quantity, and eliminating wear exceeding the radius of the first material. CONSTITUTION:A resin member end part 3 and a metal member end part 4 of the end surface of a thrust seat member A, faced to a rotational shaft 6, are integrally clamped for simultaneously machining the flat surface thereof so as to obtain the same flat surface of the end parts of both materials 3, 4. But Young's modulus <E> of resin is different from that of metal, and therefore, when the load applied to resin and metal is removed after machining them, the deviation due to elastic deformation is generated. Therefore, the first material member 1 which slightly projects during low speed running, comes in contact with the rotational shaft 6 for supporting thrust force and thereby, even if wear due to sliding contact is increased, it never exceeds the radius of the first material member 1 projected from the second material member 2 so that accelerative wear is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Minute Hand The present invention is applicable to motors that require high-speed, high-precision rotation, such as audio player motors, VTR motors,
It relates to a hydrodynamic bearing device used as a bearing means for a motor for driving a polygon mirror of a laser beam printer (LBP), and specifically includes a radial hydrodynamic bearing section and a thrust hydrodynamic bearing section. Regarding bearing devices.

(b) Conventional technology In general, hydrodynamic bearing devices using air, oil, etc. as a lubricating fluid are supported by a highly rigid lubricating fluid film during steady rotation, which causes uneven rotation and shaft runout. In recent years, it has been widely used as a bearing means with extremely high rotation accuracy, with extremely little rotation, noise and vibration during rotation. The hydrodynamic bearing device has characteristics such as a long life as it is non-contact during steady rotation, and is therefore used in audio player motors, VTR motors, and polygon mirrors in laser beam printers (LBP). It is used as a bearing means for a drive motor.

For example, as shown in FIG. 9, the LBP motor is composed of a sleeve 9 that is a fixed member and a rotating shaft 6' fitted in the sleeve 9, and the rotating shaft 6' is not shown on the surface. A large number of shallow grooves consisting of spiral grooves and herringbones are formed, and these shallow grooves and the sleeve 9
A radial dynamic pressure fluid bearing section using air as the lubricating fluid is constructed between the inner peripheral surface of the shaft and the inner circumferential surface of the shaft. Furthermore, a dynamic pressure fluid bearing for thrust using air as the lubricating fluid is similarly configured between the rotating shaft end 8' and the thrust bearing 5'. However, in the dynamic pressure fluid bearing section, the rotary shaft 6' and the sleeve 13 rotate without contact during steady state, but they come into contact at low rotational speeds.

In the thrust direction, unlike the immediate formation of a gas film in the radial direction, the rotational speed must increase considerably for the gas film stiffness to increase to support the thrust load. Therefore, until the rotational speed reaches that speed, the rotating shaft end 8' and the thrust bearing 5' continue to rotate while being in contact with each other. For this reason, the thrust bearing portion 5' has problems such as being susceptible to seizure. Conventionally, in order to reduce the contact surface, it has been either to reduce the weight of the rotating shaft 6' or to extend the rotating shaft end 8' to a predetermined radius (for example, a radius of 750 +
(w+) spherical surface, and the thrust bearing portion 5' is polished to improve the plane accuracy and inclination accuracy. However, machining the rotary shaft end 8' into a spherical surface is extremely difficult, and this has also been a factor in increasing the cost of the product.

Q→ Problem to be solved by the invention In order to reduce the contact surface between the rotating shaft end 8' and the thrust bearing 5', the rotating shaft end 8' has a radius of 7.
The thrust bearing part 5' is machined into a 50m spherical surface and polished to improve the flatness and inclination accuracy. However, because the radius of the spherical surface is large, even if the thrust bearing part 5' wears out by just 3p. Since the sliding diameter exceeds φ4 m, wear progresses at an accelerated pace. Furthermore, in the conventional thrust bearing part 5', during shrink fitting, the resin member 1' is prevented from touching the heated metal member or the sleeve 9, or being deformed by the stress of shrink fitting. Therefore, it was necessary to process it with a step as shown in Figure 10. However, even in this case, the resin member 1' was deformed by heating as shown in FIG. 11, and the sliding contact diameter was increased from the initial stage. In order to avoid this situation, the radius of the spherical surface at the upper end of the rotating shaft 6' should be made smaller, but if this is done, the space volume between the rotating shaft end 8' and the thrust bearing part 5' will increase, and this space will increase. It is not possible to reduce the radius of the spherical surface of the rotating shaft end 8' because the air present in the rotating shaft causes automatic vibrations and the sleeve vibrates in the direction of the rotating shaft 6', a so-called hammer phenomenon.

For these reasons, conventional thrust bearings have had many problems both in terms of machining and operation.

(b) Means for Solving the Problems The present invention aims to solve the above-mentioned problems, and it is an object of the present invention to solve the problems mentioned above. The thrust receiving member at one end of the sleeve is made of a first material member, and due to the difference in longitudinal elastic modulus between the first material member and the second material member, the first material member has a small longitudinal elastic modulus and a large elastic deformation. The second material member is characterized by slightly projecting out compared to the surrounding second material member.

(e) Effect With the above configuration, during low-speed rotation, the first rotating member that protrudes slightly slides on the rotating shaft to support thrust force, and even if wear due to sliding progresses, the diameter of the first material member that protrudes This prevents accelerated wear from increasing, and since the distance from the sleeve to the first material member is long, deformation of the first material member due to heating during shrink fitting is small.

(F) Embodiments Below, embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the thrust receiving member A is constructed by inserting a resin member 1 forming a first material member into a metal member 2 forming a second material member. The resin member 1 is made of polyacetal resin, 6.6 nylon, high density polyethylene, polyimide, polyamideimide, PTFE, +? It is made of commonly used self-lubricating resins such as riether ether ketone, polyether sulfone, and polyphenyline sulfide resins. Then, as shown in FIG. 1, the resin member end 3 and the metal member end 4 on the surface facing the rotating shaft 6 of the thrust receiving member A are held together and their planes are removed at the same time.
Therefore, the ends 3, 4 of both members are machined into the same plane. However, since the longitudinal elastic modulus E is different between resin and metal, the resin member end 3 and metal member end 4, which are flat due to elastic deformation under pressure during processing, will elastically deform when the load is unloaded after processing. There will be a difference in level. That is, since the elastic modulus E of the resin member 1 is smaller than the elastic modulus E2 of the metal member 2, the resin member 1 deforms more during processing than the metal member 2, and therefore has a larger return amount after processing. Therefore, as shown in FIG. 2, the end portion 3 of the resin member protrudes slightly compared to the end portion 4 of the metal member. For example, if the thickness of the thrust receiving member A is 10 mm, and the resin member 1 is made of high-density polyethylene and the metal member 2 is made of iron, the weight of the thrust receiving member A is 0.1 kg.
/ m2 pressure is applied, the amount of return after processing is 0.05 p' for iron, 10 μ for high density polyethylene,
Since the height difference is approximately 10p and the amount of wear of the resin member 1 due to use is 4p or less, this level difference is sufficient. Also, with other materials, appropriate steps can be created by appropriately changing the pressure applied during grinding.

Note that when a 10p step is created, the space volume increases and the above-mentioned air hammer phenomenon may occur. However, if the shaft diameter of the rotating shaft 6' is φ14 m, the space volume created by a 10p step is 1.5. m3, on the other hand, rotating shaft end 8
The spatial volume created by a spherical surface with a radius of 750 + wa is 2
．． 5 mm', the total is 4.0+m0, and the air hammer phenomenon occurs at about 611 II m3, so there is no problem. Conversely, if the step is hp1 and the radius of the rotating shaft end 8' is rIIIll, in order to prevent the air hammer phenomenon from occurring, at least r2h Since 1<h, it is possible to define the step range of 1<h<6000/r2.

Further, as shown in FIG. 9, the rotary shaft end 8' is generally configured with a spherical surface, but it may also be configured with a flat surface. In this case, although the initial sliding contact diameter becomes larger, there is no problem because the sliding contact diameter is guaranteed to be below a certain value, and on the contrary, the space volume between the rotating shaft end 8 and the thrust bearing part 5' can be made small, which makes it very effective against the air hammer phenomenon described above, and also makes it very easy to process the thrust bearing part 5 and the rotating shaft end part 8.
Cost reduction can also be achieved.

Alternatively, as shown in FIG. 3, the resin member 3a may be provided only in the vicinity of the contact portion facing the shaft.

Furthermore, as shown in FIG. 4, a step may be provided on the inner circumferential surface 2b' of the space at the center of the metal member 2b, and the resin member 3b may be formed by inserting the resin member 3b. It is also possible to extend the center portion of the end face of 3b further as shown in FIG.

Further, as shown in FIG. 6, the inner circumferential surface of the metal member 2C may be narrowed upward, and the resin member 3c may be configured to expand toward the shaft contact surface. As shown in FIG. 7, the center portion of the resin member end portion 3c can be made to protrude further.

Furthermore, the embodiment shown in FIG. 8 is one in which the metal member 2d of the thrust receiving member A is integrated into the sleeve 9'.
A resin member 1' is formed as an insert in the upper center portion of the sleeve 9'.

Furthermore, although not shown, by using conductive members as the first material member and the second material member, a potential is applied between the rotating shaft 6 and the sleeve 9, and the potential difference is detected. It is also possible to check the contact between the bearing 6 and the sleeve 9 and measure the bearing's lift in the thrust direction.

In the above-mentioned embodiment, a self-lubricating resin was used for the first material member and a metal such as iron was used for the second material member, but the present invention is not limited to this. and a resin having a large longitudinal elastic modulus may be used for the second material member, and a metal having a small longitudinal elastic modulus for the first material member,
A metal having a large longitudinal elastic modulus may be used for the second material member, in short, the first material member and the second material member are made of materials having different longitudinal elastic modulus, and the longitudinal elastic modulus E of the first material member is may be smaller than the longitudinal elastic modulus E2 of the second material member.

(g) As described in detail, according to the present invention, the first material member is formed so as to be surrounded by the second material member, and the end surface thereof is located at a distance from the end surface of the second material member. Because of the fixed amount of protrusion, even if wear progresses due to sliding contact with the shaft, the diameter will not exceed the diameter of the first material member, preventing accelerated wear of the thrust receiving member. Since the distance to the second material member in sliding contact with the second material member is long, deformation of the second material member due to heating during shrink fitting can be reduced. This eliminates the need for difficult work such as machining the shaft end surface into a spherical surface, thereby significantly reducing costs and significantly improving the accuracy and durability of the thrust receiving member.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the state of an embodiment of the present invention during processing, FIG. 2 is a sectional view showing the state after processing, and FIG. 3 is a sectional view showing a partially modified embodiment. 4 is a cross-sectional view showing the state of another embodiment during processing, FIG. 5 is a cross-sectional view showing the state after processing, and FIG. 6 is a cross-sectional view showing the state of a further modified embodiment during processing. FIG. 7 is a sectional view showing the state after processing, and FIG. 8 is a sectional view showing still another embodiment. FIG. 9 is a first cross-sectional view showing an example of a conventional motor device.
0 and 11 are cross-sectional views showing the thrust receiving member in different states. 1... First material member (resin member), 2... Second material member (metal member), 3... First material member end,
4... Second material member end, 5... Thrust bearing, 6... Rotating shaft, 8... Rotating shaft end, 9...
Sleeve, A... Thrust receiving member.

Claims (5)

[Claims] (1) Comprising a shaft that rotates relatively and a sleeve fitted to the shaft, the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve constitute a radial dynamic pressure fluid bearing part, and A dynamic pressure fluid bearing device in which a thrust dynamic pressure fluid bearing section is configured by one end surface and a thrust receiving member provided on the sleeve, wherein the thrust receiving member is connected to a portion near the contact portion with the one end surface of the shaft. A first material member having a longitudinal elastic modulus E_1 and a longitudinal elastic modulus E_2 forming the periphery of the first material member.
A hydrodynamic bearing device formed from a second material member, characterized in that a longitudinal elastic modulus E_1 of the first material member is smaller than a longitudinal elastic modulus E_2 of the second material member. (2) The first material member protrudes by a predetermined amount toward the shaft end surface with respect to the second material member.
Dynamic pressure fluid bearing device described in . (3) The amount of protrusion h (μm) of the first material member relative to the second material member is within the range of 1<h<6000/r^2 with respect to the radius of the shaft (mm). A hydrodynamic bearing device according to claim 2. (4) The hydrodynamic bearing device according to claim 1, wherein the first material member is made of a self-lubricating resin. (5) The hydrodynamic bearing device according to claim 1, wherein both the first material member and the second material member are made of conductive material.