JPH06159366A - Static pressure gas bearing - Google Patents

Abstract

(57) [Summary] [Purpose] It is resistant to seizure and can be rotated at high speed, and it can be used regardless of whether the external atmosphere is dusty or clean. [Structure] The thrust bearing portion 6 is arranged close to one side of the radial bearing portions 3 and 4 to form a bearing body 11. The change in the thrust clearance of the thrust bearing portion 6 due to the temperature rise is small, seizure hardly occurs, and high-speed rotation is possible. Dustproof covers 21 and 22 are provided at both ends of the bearing body 11 to form dustproof chambers 23 and 24. Dustproof chamber 2 according to the external atmosphere
Air can be supplied to 3, 24, or conversely, suction and exhaust can be performed, and the range of use is expanded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrostatic gas bearing used as an air spindle, a main shaft support bearing for precision machine tools and the like.

[0002]

2. Description of the Related Art Conventionally, as a static pressure gas bearing, as shown in FIG. 2, there is a space L on both sides of a static pressure gas bearing portion a.
It is known that the thrust collars c and d (rotors) provided at both ends of the rotary shaft b are provided (precision machinery Vo).
l.50 No.5 Refer to P.8). And, by itself, the air supply grooves e and f and the exhaust gas groove g are formed, and air is supplied from the air supply grooves e and f to the bearing surfaces h and i to rotate the rotating shaft b and the thrust collar c,
An air film is formed between the inner surface of d and the inner surface.

[0003]

However, in such a static pressure gas bearing, the length L between the thrust collars c and d is long, the thrust collars c and d are separated on both sides, and the thrust bearings are located on both sides. Therefore, the thermal deformation caused by the heat generated by the rotation of the rotating shaft b is large, the gap in the thrust direction becomes small, and seizure may occur.

There is also known a thrust collar provided at an intermediate portion between two radial bearing portions. In such a case, exhaust gas is formed between the outer peripheral surface of the shaft end portion and the housing. Since it is designed to be discharged from the gap, if there is a lot of dust in the air, it may enter the bearing part.On the contrary, if the outside is a clean room, the dust in the exhaust will enter the clean room. Will be scattered.

The present invention provides a hydrostatic bearing which is resistant to seizure, can rotate at high speed, and can be used regardless of whether the external atmosphere is dusty or clean.

[0006]

The present invention has a radial bearing portion for rotatably supporting a rotary shaft and a thrust bearing portion for supporting a thrust collar provided on the rotary shaft. It is premised on a static pressure gas bearing in which air is supplied from an air supply hole opened in the bearing surface to form an air film between the rotary shaft and the thrust collar.

Further, according to the present invention, a bearing body is constructed by arranging the thrust bearing portion close to one side of the radial bearing portion, and a dustproof cover is provided at each end portion of the bearing body to provide a dustproof chamber. Is formed, and a communication passage that can supply gas from the outside into the dustproof chamber or that can discharge gas inside the dustproof chamber to the outside is connected to the dustproof cover.

[0008]

[Operation] Since the thrust bearing portion is arranged close to one side of the radial bearing portion to form the bearing main body,
The change in the thrust clearance of the thrust bearing portion due to the temperature increase is small.

The dust-proof chambers formed at both ends by the dust-proof covers prevent the discharge of dust to the outside or the intrusion of dust from the outside.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings.

In FIG. 1 showing a schematic structure, reference numeral 1 is a static pressure gas bearing, and radial bearing portions 3 and 4 for rotatably supporting a rotary shaft 2 and a thrust collar 5 provided on the rotary shaft 2 are sandwiched from both sides. And a thrust bearing portion 6 for supporting it.
Then, air is supplied from the air supply holes 7 and 8 formed in the bearing surfaces of the radial bearings 3 and 4 to form an air film with the rotary shaft 2, while the air supply holes formed in the bearing surface of the thrust collar 5 are formed. Air is supplied from the pores 9 and 10 to form an air film between the air and the thrust collar 5.

The thrust bearing portion 6 is arranged close to one side of the radial bearing portions 3 and 4, and the bearing body 11 is constituted by them.

In addition, the air supply holes 7 of the radial bearings 3 and 4,
8 and one air supply hole 9 of the thrust bearing portion 6 are provided in the expansion chamber 12
The expansion chamber 12 is connected to an air supply passage 13 to which air is supplied by an air pump or the like (not shown). A branch air supply passage 14 that is branched from the middle of the air supply passage 13 is formed, and the branch air supply passage 14 communicates with the other air supply hole 10 of the thrust bearing portion 6.

Dustproof covers 21 and 22 are attached to both ends of the bearing body 11 by screws (not shown) to form dustproof chambers 23 and 24, respectively. And
The dustproof covers 21 and 22 prevent the exhaust of the bearing leaking from both ends of the bearing body 11 from flowing out, or prevent dust from entering from the outside. A communication passage (not shown) is connected to the dustproof covers 21 and 22 through communication holes 25 and 26. Therefore, when the external atmosphere is a dusty atmosphere and the dust in the external atmosphere is not desired to enter the bearing main body 11, the dustproof chambers 23, 24 are communicated through the communication passages from the communication holes 25, 26 by an external air pump or the like. The air can be supplied to the inside, or if the outside atmosphere is a clean atmosphere such as a clean room and the dust inside the bearing body 11 is not to be discharged into the outside atmosphere, the exhaust air inside the dustproof chambers 23 and 24, etc. An external vacuum pump or the like allows suction and exhaust from the communication holes 25 and 26 through the communication passage.

The wall thickness W of the thrust collar 5 is smaller than the space L between the bearings shown in FIG. 2, and the thermal deformation due to the temperature rise caused by the rotation of the rotary shaft 2 is small. The change is small, and the thrust bearing part 6
It is difficult for seizure to occur.

The diameter D2 of the inner peripheral surface of the dustproof covers 21 and 22 facing the outer peripheral surface of the rotary shaft 2 is larger than the diameter D1 (about 5 μm) of the inner peripheral surface of the radial bearings 3 and 4. It is set to be large.

With the above arrangement, the change in the thrust clearance of the thrust bearing portion 6 due to the temperature rise is small,
It is harder to seize than the conventional one (see FIG. 2) and can rotate stably even at high speed.

Further, the dustproof covers 21 and 22 are attached to the bearing main body 1
1. Dust-proof covers 2 provided at both ends of the 1 according to the external atmosphere
Since air can be supplied to the dust-proof chambers 23 and 24 in 1 and 22 or suction and exhaust can be performed on the contrary, the range of use as a static pressure gas bearing is widened.

[0019]

As described above, according to the present invention, since the thrust bearing portion is arranged close to one side of the radial bearing portion to form the bearing body, the change in the thrust clearance of the thrust bearing portion due to the temperature rise is small. As a result, seizure can be prevented and high-speed rotation is possible.

Further, a dustproof cover is provided at both ends of the bearing body to form a dustproof chamber, and a communication passage is connected to which gas from the outside can be supplied to the dustproof chamber or gas in the dustproof chamber can be discharged to the outside. Therefore, it is possible to use the external atmosphere regardless of whether it is a dusty atmosphere or a clean atmosphere.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a hydrostatic gas bearing.

FIG. 2 is a schematic view of a conventional example.

[Explanation of symbols]

 1 Hydrostatic gas bearing 2 Rotating shaft 3,4 Radial bearing part 5 Thrust collar 6 Thrust bearing part 7,8 Air supply hole 9,10 Air supply hole 11 Bearing body 21,22 Dust cover 23,24 Dust chamber 25,26 Communication hole

Claims (1)

[Claims] 1. An air supply hole having a radial bearing portion for rotatably supporting a rotating shaft and a thrust bearing portion for supporting a thrust collar provided on the rotating shaft, and having an opening in a bearing surface of both bearing portions. A static pressure gas bearing that supplies more air to form an air film between the rotary shaft and the thrust collar, and the thrust bearing portion is arranged closer to one side of the radial bearing portion to form a bearing body. , A dustproof chamber is formed by disposing dustproof covers at both ends of the bearing body, respectively, and a gas can be supplied to the dustproof chamber from the outside or the gas in the dustproof chamber can be exhausted to the outside. A hydrostatic gas bearing characterized in that the passages are connected.