JPH10281146A - Dynamic pressure bearing - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable high-speed rotation by eliminating bias of lubricating oil due to centrifugal force generated during rotation. SOLUTION: A ring-shaped annular groove 5 whose bottom is formed in a horizontal plane is filled with lubricating oil 7, and a ring body 6 in which inclined surfaces 6a for generating dynamic pressure are formed at appropriate intervals on a lower surface is fitted. In the dynamic pressure bearing which is rotatable about the vertical axis, a communication hole 8 connecting the outer side portion 5b and the inner side portion 5b of the bottom surface of the annular groove 5 is formed below the bottom surface of the annular groove 5. The lubricating oil 7 formed and moved outward by centrifugal force
Is returned to the inside through the communication hole 8 to circulate the lubricating oil 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic pressure bearing used for supporting a vertical load rotating in a horizontal plane, such as a rotary lapping plate.

[0002]

2. Description of the Related Art A lapping machine extremely dislikes the application of vibration to a workpiece being polished. Therefore, a dynamic pressure plane bearing is most suitable for a bearing of a rotary platen supporting a workpiece. Therefore,
The present applicant has already applied for a lapping machine using a dynamic pressure bearing as Japanese Patent Publication No. 61-54544. FIG.
12 to 12 show a dynamic pressure plane bearing used for the lapping machine, FIG. 3 is a longitudinal sectional view, and FIG.
FIG. 4 is a plan view showing an upper portion of the device removed. As shown in the figure, the dynamic pressure plane bearing is formed between a disk bearing 2 that supports a lower lap disk 1 and a bearing base (base) 3. Specifically, a ring-shaped annular groove 5 is formed on the outer peripheral portion of the upper surface of the bearing base 3, and a ring body 6 having a rectangular cross section is fitted into the annular groove 5.

The disk receiver 2 is mounted on the upper surface of the ring body 6, and both are integrally fixed by screws (not shown). The ring body 6 is a perspective view of FIG. 5, a bottom view of FIG.
As shown in the cross-sectional view of FIG. 7, slopes 6a for generating dynamic pressure are formed at equal intervals on the lower surface serving as a slip surface. A horizontal surface 6b is formed at the lower position end of the slope 6a, and a radial groove 6c is formed between the horizontal surface 6b and the higher position end of the adjacent slope 6a. The horizontal surface 6b contacts the bottom surface of the annular groove 5 to support the thrust load when the bearing is stationary.

[0004] When the slide bearing operates, the operation of FIG.
As shown in the cross-sectional view of FIG. 6, the ring body 6 is rotated from the lower end to the higher end of the slope 6a in a state where the annular groove 5 is filled with the lubricating oil 7. In the stopped state, as shown in the sectional view of FIG.
Are supported in contact with the annular groove 5, but when the ring body 6 starts rotating, the arrangement of the groove 6 c and the slope 6 a of the ring body 6 narrows in the traveling direction with respect to the bottom surface of the annular groove 5. Therefore, the pressure rises while the viscous lubricating oil 7 passes between them, and an oil film is formed between the lower surface of the ring body 6 and the annular groove 5. As a result, as shown in FIG. 10, the ring body 6 supported by the annular groove 5 via the oil film
It is rotated while floating above.

[0005]

In the above-mentioned dynamic pressure bearing, the distance between the position where the sliding surface is formed and the center of rotation, that is, the radius, is relatively large. Becomes larger. The sectional view of FIG.
This shows the case of relatively low-speed rotation. When the generated centrifugal force is small, the liquid level of the lubricating oil 7 in the annular groove 5 is almost the same in the inner portion 5a and the outer portion 5b of the ring body 6. However, when the rotation speed increases, the centrifugal force increases as shown in FIG. 12, and the lubricating oil 7 in the annular groove 5 starts to be pushed outward, and the liquid level of the inner portion 5a of the ring body 6 decreases. The liquid level of the outer portion 5b rises.

[0006] This is because as the speed of the lubricating oil 7 attached to the ring body 6 and moving in the circumferential direction increases with the rotation of the ring body 6, the radially outward acceleration (centrifugal force) increases. The increased velocity component increases the dynamic pressure, and the head of the lubricating oil on the outer side 5b rises with respect to the inner part 5a of the annular groove 5. As a result, the liquid level of the inner part 5a decreases and The liquid level of the portion 5b rises. This liquid level is a paraboloid as is well known, and the liquid level can be calculated from the rotational speed and the radius at that position.

The difference between the liquid level of the inner portion 5a and the liquid level of the outer portion 5b also appears as a difference in centrifugal force at each position. Here, when the rotation speed of the ring body 6 is further increased, the liquid level of the inner portion 5a further decreases,
The supply of the lubricating oil 7 to the oil film formed on the lower surface of the ring body 6 is reduced. As a result, the oil film becomes thinner, and the sliding resistance increases accordingly. Further, when the liquid level is further lowered, the supply of the lubricating oil 7 to the oil film is finally cut off and the oil film is interrupted, and the horizontal surface 6b of the ring body 6 comes into direct contact with the annular groove 5 to cause burning. .

[0008]

In order to solve the above-mentioned problems, the present invention provides a ring-shaped annular groove having a bottom surface formed in a horizontal plane as a bearing, and corresponds to the annular groove of the bearing. A dynamic pressure generating surface is formed at an appropriate interval on the lower surface of the ring body protruding downward to form a shaft, and the shaft is fitted in a state where lubricating oil is filled in the annular groove of the bearing, and the shaft is vertically fitted. In a dynamic pressure plane bearing that is freely rotatable around an axis, a communication hole communicating between an outer side portion and an inner side portion of the bottom surface of the annular groove is formed below the bottom surface of the annular groove. As a result, the lubricating oil that has been swept outward by the centrifugal force during the rotation due to the centrifugal force returns to the inside of the annular groove via the communication hole and is circulated.

[0009]

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 cross-sectional view of a main part showing an embodiment of the present invention, and FIG. 2 is a plan view showing the whole of FIG. This embodiment is applied to a lapping machine in the same manner as the conventional technology described above, and the overall configuration is the same as the configuration of the conventional dynamic pressure bearing described in FIGS. A description of the same parts will be omitted. This embodiment is, as shown in FIGS. 1 and 2, a bottom surface of an annular groove 5 formed in a bearing base 3. A hole in the vertical direction is formed at the position of 5b, and the lower ends thereof are connected by the hole in the horizontal direction to form a communication hole 8 having a U-shape as a whole. The communication holes 8 are provided at four positions on the bearing base 3 at a 90-degree pitch.

Next, the function of these communication holes 8 will be described. When the ring body 6 supporting the disk receiver 2 rotates,
As shown in FIG. 12, the lubricating oil 7 in the annular groove 5 is drawn by the rotation of the ring body 6 due to its viscosity and starts flowing in the same direction. As the flow rate of the lubricating oil 7 increases, the liquid level of the lubricating oil 7 on the outer portion 5b tends to increase. However, here, since the communication hole 8 is formed in the bearing base 3 which is always stationary with respect to the rotating or moving ring body 6 and the lubricating oil 7, the lubricating oil 7 is transferred from the outer portion 5b to the communication hole 8 And flows out to the opposite inner part 5a. This is because the lubricating oil 7 moves from the high head to the low head.
Since the fluid flows through the lower head pipe, it can be said that the communication hole 8 acts as an inverse siphon.

In this way, the lubricating oil 7 flows from the inner portion 5a to the outer portion 5b through the lower surface of the ring body 6 by centrifugal force to raise the liquid level. However, the lubricating oil 7 flowing into the outer portion 5b It flows into the communication hole 8 and the inner portion 5a
Returned to That is, during rotation, the lubricating oil 7 in the annular groove 5 moves from the inner portion 5a to the lower surface of the ring body 6 and the outer portion 5
b, the communication hole 8, and then again to the inner part 5a. Thereby, even if the ring body 6 rotates at a high speed, the increase in the liquid level of the outer portion 5b is slightly suppressed. As a result, the dynamic pressure bearing according to this embodiment can suppress the increase in the sliding resistance at the time of high-speed rotation and can prevent the burn-in at the time of high-speed rotation, which has conventionally occurred.

In the embodiment, the mechanism for generating the dynamic pressure on the lower surface of the ring body 6 is a combination of the inclined surface 6a, the horizontal surface 6b, and the groove 6c. However, it is known as another general dynamic pressure generating mechanism. The present invention can be similarly applied to a Rayleigh step bearing, a tapered land bearing, and the like. Further, the dynamic pressure bearing can be used for a large-sized and high-speed rotating device or apparatus other than the lapping machine.

[0013]

As described above, according to the present invention, the communication hole connecting the outer side portion and the inner side portion of the bottom surface of the annular groove is formed below the bottom surface of the annular groove. Since the lubricating oil moved to the outer portion of the annular groove by the centrifugal force returns to the inner portion and circulates, the oil film is not interrupted, and the large dynamic pressure bearing can rotate at high speed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of an embodiment of the present invention.

FIG. 2 is a plan view showing the whole of FIG. 1 by removing an upper part thereof;

FIG. 3 is a longitudinal sectional view of a conventional example.

FIG. 4 is a plan view showing the whole of FIG. 3 by removing an upper part thereof;

FIG. 5 is a perspective view showing a main part of FIG. 3;

FIG. 6 is a bottom view of FIG. 5;

FIG. 7 is a partial sectional view of FIG. 5;

FIG. 8 is a sectional view showing the operation of the conventional example.

FIG. 9 is a sectional view showing the operation of the conventional example.

FIG. 10 is a sectional view showing the operation of the conventional example.

FIG. 11 is a sectional view showing the operation of the conventional example.

FIG. 12 is a sectional view showing the operation of the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lower lap disk 2 Disk receiver 3 Bearing stand (base) 5 Annular groove 5a Inner part of groove 5b Outer part of groove 6 Ring body 6a Slope 6b Horizontal plane 6c Annular groove 7 Lubricating oil 8 Communication hole

Claims (1)

[Claims] A ring-shaped annular groove having a bottom surface formed in a horizontal plane as a bearing portion, and a dynamic pressure generating surface is formed on a lower surface of a ring body projecting downward corresponding to the annular groove of the bearing portion. A dynamic pressure plane bearing, which is formed at an appropriate interval to form a shaft portion, and the shaft portion is fitted in a state in which lubricating oil is filled in the annular groove of the bearing portion to freely rotate around a vertical axis, A dynamic pressure plane bearing, wherein a communication hole communicating between an outer side portion and an inner side portion of a bottom surface of the annular groove is formed below a bottom surface of the annular groove.