JPS6065907A - Dynamic pressure gas bearing - Google Patents

Abstract

PURPOSE:To enable to easily adjust a clearance between a pad and a pivot, in a main rotary shaft supported by a pad, by supporting the pad by a pivot so as the pad can oscillate and by connecting a load-applying device and a movable spacer in series to the pivot. CONSTITUTION:A main shaft 1 is supported by a pad 2, and the pad 2 is supported by a pivot 3 so that the pad can oscillate. The pivot 3 can freely move in the radial directions of the main shaft 1 in a bearing housing 7, its head comes to contact with a plate spring 13 attached to the bearing housing 7, and a reverse load is applied to the pivot 3 by clamping a screw 12 of the plate spring 13. Further, a spacer 10 is inserted between the bearing housing 7 and the plate spring 13, and the spacer 10 can move by clamping its screw 11. As a result, an initially set clearance 5 can finally be freely adjusted in a state where the plate spring 13 and the pivot 3 are apart from each other. Thus, a small clearance between the pad 2 and the pivot 3 can be easily adjusted and the starting characteristic can be improved.

Description

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

[Background of the invention]

The bearing clearance during operation of a pad-type hydrodynamic gas bearing increases as the rotational speed of the main shaft increases.

However, in order to produce stable rotation of the main shaft.

It is necessary to limit the bearing clearance within a certain range. For this reason, measures have been taken to apply a preload of 1 to the pad using a spring or the like. However, when the main shaft is stopped, if 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 avoid applying a preload while the vehicle is stopped.

Conventional examples of the measures described above will be explained. Figure 1 is
This is an example. The main shaft 1 is supported by a pad 2, and the pad 2 is swingably supported by a pivot 3. The pivot 3 is located inside the cylinder 6 and has a structure that allows it to move freely in the radial direction of the main shaft. A load equal to the required preload 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 pivot 3
The assembly of the cylinder 6 and the 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, it is possible to adjust the gap δ between the pad 2 and the pivot 3 so that the load of the spring 5 is not directly applied to the pad 2 when the main shaft is stopped.

By doing this, when the spindle is stopped, no preload is applied to the pad 2, so that the spindle l can be easily started. Furthermore, when the rotational speed of the spindle 1 increases and the gap between the pad 2 and the spindle 1 becomes larger than δ, the preload from the spring 3 acts on the pad 2 for the first time, reducing the gap between the spindle 1 and the pad 2. By limiting it within a certain value, it is possible to produce stable operation of the main shaft l.

FIG. 2 shows another example. Pad 2. The load applying mechanism using the pivot pre-3 and the spring 5 is the same as the example shown in FIG. 1, but the method of adjusting the initial gap δ between the pad 2 and the pivot 3 is modified. 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 gap δ between the pad 2 and the pivot 3 is secured.

However, the initial gap δ between the pad 2 and the pivot 3 is usually very small, and is about 1 to 2 μm in a small bearing device. Therefore, it is very difficult to adjust these values by adjusting the thickness of the screw or washer, as shown in the example of FIGS.

[Purpose of the invention]

An object of the present invention is to enable easy adjustment of a very small gap between a pad and a pivot in a pad type hydrodynamic gas bearing.

[Summary of the invention]

When adjusting very small gaps such as those 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, and it is necessary to combine these mechanical elements. The present invention combines the thread pitch and the spacer slope to adjust very small gaps.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on an embodiment shown in FIGS. 3 to 5.
・ Government 1st.

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 can freely move in the radial direction of the main shaft 1, and its tip can come into contact with a leaf spring 13 attached to the bearing housing 7.
The pivot 3 is preloaded by tightening and the leaf spring 13.

A spacer 10 is provided between the bearing housing 7 and the leaf spring 13.
can be inserted. This spacer IO has a sloped contact surface with the leaf spring 13, and by turning the screw 11, it moves with respect to the bearing housing 7, and if it moves further, the leaf spring 13 that preloads the pivot 3 will move. Pivot 3
The gap δ can be freely adjusted to the initial setting while separating the gap δ.

FIG. 4 shows the situation.

Now, set the slope of the spacer lO to 0.01. If the screw 11 is threaded with one thread and the pitch is Q, 2 vs., by rotating the screw 11 once, the gap between the pivot 3 and the leaf spring 13 is reduced to 2μ.
m can be adjusted, and even a slight gap of 1 to 2 μm can be easily adjusted.

・ 4 ・ FIG. 5 is a plan view of FIG. 4, but the spacer I
The shape of the O is taken into consideration.

〔Effect of the invention〕

As described above, according to the present invention, when adjusting a small gap between the pivot and the leaf spring, by using a spacer with a slope, a gap on the order of 1 μm can be easily adjusted. This has the effect of making it easier to start up the pad type hydrodynamic gas bearing.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing the structure of a conventional pad-type hydrodynamic gas bearing, and FIGS. 3 and 4 are cross-sectional views showing the structure of a hydrodynamic gas bearing according to the present invention. This is the state with the spacer pulled out. FIG. 5 is a plan view of FIG. 4. l...Main axis, 2! ...Pad, 3...
... Pivot, 7... Bearing housing, lO
...Spacer, 11...Screw, 12...
...Screw, 13...Plate spring size 4 Fig. 5 Fig. 39-

Claims (1)

[Claims] Mark 1. The rotating main shaft is supported by pads! In a gas bearing device, a pit for rocking support is arranged in the bearing housing, a load adding device is installed at the other end of the pivot, and a pit is placed between the load adding device and the bearing housing. A dynamic pressure gas bearing characterized by having a movable spacer. 2. The dynamic pressure gas bearing according to claim 1, wherein the contact surface between the spacer and the load applying device has a slope.