JPH0158767B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a dynamic pressure gas bearing, and more particularly to a mechanism for adjusting the preload applied to pads in a pad type dynamic pressure gas bearing.

[Background of the invention]

Pad type dynamic pressure gas bearing during operation〓
The distance increases as the rotational speed of the spindle increases. However, in order to produce stable rotation of the main shaft, it is necessary to limit the distance between the bearings within a certain range. For this reason, measures have been taken to preload the pad using a spring or the like. However, when the main shaft is stopped and a preload similar to that applied during rotation is applied, the friction torque between the main shaft and the pad becomes abnormally large, and it may become impossible to start the main shaft. Therefore, it is also necessary to take measures to prevent preload from being applied while the vehicle is stopped.

Conventional examples of the measures described above will be explained. 1st
The figure is an example. The main shaft 1 is supported by a pad 2, and the pad 2 is supported swingably by a pivot 3. The pivot 3 is located inside the cylinder 6 and is structured to be freely movable in the radial direction of the main shaft. A load equal to the preload required during rotation is applied to the pivot 3 by the spring 5 and the spring retainer 4. On the other hand, since the cylinder 6 is fixed to the bearing housing 7 by a screw structure, the assembly of the pivot 3 and cylinder 6 can be moved in the radial direction with respect to the main shaft 1. Therefore, by moving the cylinder 6 in the radial direction, the load of the spring 5 is not directly applied to the pad 2 when the main shaft 1 is stopped.
The distance between pad 2 and pivot 3 can be adjusted to δ.

By doing this, when the main spindle is stopped, no preload is applied to the pad 2, so starting the main spindle 1 is easy. Furthermore, when the rotational speed of the main shaft 1 increases and the distance between the pads 2 and the main shaft 1 becomes larger than δ, the preload by the spring 3 acts on the pads 2 for the first time, causing the distance between the main shaft 1 and the pads 2 to increase. By limiting the distance between 0 and 1 within a certain fixed value, stable operation of the main shaft 1 can be achieved.

FIG. 2 shows another example. The preload applying mechanism using the pad 2, pivot 3, and spring 5 is the same as the example shown in FIG. 1, but the method of adjusting the initial distance δ between the pad 2 and the pivot 3 has been devised. That is, a washer 8 is provided between the bearing housing 7 and the pivot 3. By adjusting the thickness of this washer 8, the initial distance δ between the pad 2 and the pivot 3 is secured.

However, the initial distance δ between pad 2 and pivot 3
is usually very small, 1 to 1 for small bearing devices.
It will be about 2 μm. Therefore, it is very difficult to adjust these values by adjusting the thickness of the screw or washer, as shown in the examples of FIGS.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to easily adjust a very small gap between a pad and a pivot with a simple structure in a pad-type hydrodynamic gas bearing.

[Summary of the invention]

When adjusting the extremely small distances mentioned above, it is difficult to use only a single mechanical element such as the pitch of the screw or the thickness of the washer as in the conventional example, so it is possible to adjust the distance by combining these mechanical elements. It becomes necessary to do so. The present invention provides a wedge-shaped spacer in the gap between the housing surface and the leaf spring that presses the pivot, moves and sets the spacer with a screw, and utilizes the pitch of the screw and the slope of the spacer. It is a device that allows very small gaps to be easily adjusted with a simple structure.

[Embodiments of the invention]

The present invention will be explained below with reference to an embodiment shown in FIGS. 3 to 5. The main shaft 1 is supported by a pad 2, and the pad 2 is supported by a pivot 3 so as to be swingable. The pivot 3 is located inside the bearing housing 7 and is able to move freely in the radial direction of the main shaft 1. Its tip can come into contact with a leaf spring 13 attached to the bearing housing 7, and the pivot 3 can be moved freely in the radial direction of the main shaft 1. A leaf spring 13 preloads the pivot 3. In this way, there is nothing protruding outward from the leaf spring 13, and a bearing can be constructed in a small space.

A spacer 10 can be inserted between the bearing housing 7 and the leaf spring 13. This spacer 10
The contact surface with the leaf spring 13 is sloped, and by turning the screw 11, it moves relative to the bearing housing 7, and as it moves further, the leaf spring 13 that is applying a preload to the pivot 3 and the pivot 3 are separated. While separating them, the gap can finally be freely adjusted to the initial setting gap δ. In this way, the gap can be set with a simple structure. FIG. 4 shows the situation.

Now, if the slope of the spacer 10 is 0.01 and the screw 11 is a single thread with a pitch of 0.2 mm, then the screw 11 is 1
By rotating, the pivot 3 and leaf spring 13 are
The distance can be adjusted by 2 μm, and even a slight adjustment of 1 to 2 μm can be easily made.

FIG. 5 is a plan view of FIG. 4, and the shape of the spacer 10 is designed so that the pivot 3 is not restricted even if the spacer 10 is moved.

〔Effect of the invention〕

As described above, according to the present invention, the structure is simple and the gap between the pivot and the leaf spring can be adjusted by using a combination of an inclined spacer and a screw. This can be done easily, and as a result, the effect is that the simply configured pad-type dynamic pressure gas bearing can be started easily.

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing the structure of a conventional pad-type hydrodynamic gas bearing, FIGS. 3 and 4 are cross-sectional views showing the structure of a hydrodynamic gas bearing according to the present invention, and FIG. This is the state with the spacer pulled out.
FIG. 5 is a plan view of FIG. 4. 1... Main axis, 2... Padded, 3... Pivot,
7...Bearing housing, 10...Spacer, 1
1...screw, 12...screw, 13...leaf spring.

Claims (1)

[Claims] 1. In a hydrodynamic gas bearing in which a rotating main shaft is supported by a pad, one end of a pivot provided through the bearing housing is in swingable contact with the pad, and the other end is attached to the bearing housing. A wedge-shaped spacer for adjusting the gap between the pivot and the leaf spring is moved by a screw into the gap between the bearing housing surface and the leaf spring so as to come into contact with a leaf spring provided with a gap from the surface. A dynamic pressure gas bearing characterized by being settable.