JP2008039110A - Static pressure gas bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a static pressure gas bearing device which can increase the axial length of a static pressure gas bearing without largely lowering the bearing performance and mechanical strength of the static pressure gas bearing. <P>SOLUTION: A radial static pressure gas bearing 2 having a radial bearing surface 2a opposed to the outer peripheral surface of a rotary shaft 1 keeps the outer peripheral surface equipped with a plurality of gas supplying annular grooves 6, 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a static pressure gas bearing device used for, for example, a precision machine tool.

  An example of a conventional static pressure gas bearing device used for a precision machine tool is shown in FIG. The static pressure gas bearing device shown in the figure includes a rotary shaft 1, a cylindrical radial static pressure gas bearing 2 having a radial bearing surface 2a facing the outer peripheral surface of the rotary shaft 1, and the radial static pressure gas bearing. And a cylindrical bearing housing 3 that accommodates the gas 2, and in the bearing housing 3, a pressurized gas is supplied to an air supply annular groove 4 formed in the central portion of the outer peripheral surface of the radial static pressure gas bearing 2. A pressurized gas supply path 5 is formed.

In such a static pressure gas bearing device, when the axial length of the radial static pressure gas bearing 2 is increased, the pressure distribution of the pressurized gas ejected from the radial bearing surface 2a of the radial static pressure gas bearing 2 is changed to the radial static pressure gas. A problem arises that the bearing 2 becomes non-uniform in the axial direction and the bearing performance of the radial static pressure gas bearing 2 is lowered. Therefore, as shown in FIG. 4, a design has been devised in which the groove width of the air supply annular groove 4 formed on the outer peripheral surface of the radial static pressure gas bearing 2 is increased (see, for example, Patent Document 1).
Further, in order to increase the rigidity, the bearing supply pressure is often increased for use.
JP 7-317768 A

  In such a static pressure gas bearing device, it is possible to prevent the pressure distribution of the pressurized gas ejected from the radial bearing surface of the radial static pressure gas bearing from becoming uneven in the axial direction of the radial static pressure gas bearing. Further, the mechanical strength of the radial static pressure gas bearing is lowered by an amount corresponding to the increase in the groove width of the air supply annular groove. For this reason, the radial pressure gas bearing is likely to be deformed by the gas pressure acting on the annular groove for supplying air (particularly when the pressure is 0.5 MPa or more), and the bearing performance of the static pressure gas bearing device is deteriorated. was there.

  The present invention has been made paying attention to the above-mentioned problems, and its purpose is to increase the axial length of the hydrostatic gas bearing without significantly reducing the bearing performance and mechanical strength of the hydrostatic gas bearing. An object of the present invention is to provide a static pressure gas bearing device capable of performing the above.

  In order to achieve the above object, a first invention is formed on a cylindrical radial static pressure gas bearing having a radial bearing surface opposed to an outer peripheral surface of a rotating shaft, and an outer peripheral surface of the radial static pressure gas bearing. And a bearing housing having a pressurized gas supply path for supplying pressurized gas to the air supply annular groove, wherein the air supply annular groove is formed on the outer peripheral surface of the radial static pressure gas bearing. It is characterized in that a plurality are provided.

  A second invention has a rotary shaft, a flange provided at one end of the rotary shaft, an annular thrust bearing surface facing the inner flange surface of the flange, and a radial facing the outer peripheral surface of the rotary shaft A cylindrical static pressure gas bearing having a bearing surface, and a bearing housing having a pressurized gas supply path for supplying pressurized gas to an air supply annular groove formed on the outer peripheral surface of the static pressure gas bearing. In this static pressure gas bearing device, a plurality of the annular grooves for supplying air are provided on the outer peripheral surface of the static pressure gas bearing.

  In the static pressure gas bearing device according to the present invention, the pressure distribution of the pressurized gas ejected from the radial bearing surface is substantially uniform in the axial direction of the static pressure gas bearing. The axial length of a hydrostatic gas bearing can be increased without reducing the mechanical strength

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a cross-sectional view of a static pressure gas bearing device according to the first embodiment of the present invention. The hydrostatic gas bearing device shown in the figure includes a rotating shaft 1, a cylindrical radial hydrostatic gas bearing 2 having a radial bearing surface 2a facing the outer peripheral surface of the rotating shaft 1, and the radial hydrostatic gas bearing. And a cylindrical bearing housing 3 that accommodates the gas 2, and pressurized gas is supplied into the air supply annular grooves 6 and 7 formed on the outer peripheral surface of the radial static pressure gas bearing 2 in the bearing housing 3. A pressurized gas supply path 5 is formed.

Here, assuming that the axial length of the radial static pressure gas bearing 2 is L, the air supply annular grooves 6 and 7 have a groove width of, for example, 1/10 L to 1/4 L on the outer peripheral surface of the radial static pressure gas bearing 2. Is formed. When the radial thickness of the radial static pressure gas bearing 2 is T, the air supply annular grooves 6 and 7 are formed on the outer peripheral surface of the radial static pressure gas bearing 2 at a groove depth of, for example, 1 / 10T to 1 / 2T. Is formed.

  In such a configuration, the pressurized gas supplied from the pressurized gas supply path 5 to the annular grooves 6 and 7 for supplying air passes through the inside of the radial static pressure gas bearing 2 and faces the outer peripheral surface of the rotating shaft 1. It ejects from the radial bearing surface 2a. At this time, since the pressure distribution of the pressurized gas ejected from the radial bearing surface 2a becomes a substantially uniform pressure distribution in the axial direction of the radial static pressure gas bearing 2, the bearing performance of the radial static pressure gas bearing 2 is greatly reduced. Therefore, the axial length of the radial static pressure gas bearing 2 can be increased. Further, the mechanical strength of the radial static pressure gas bearing 2 is not greatly reduced unlike the case where an annular groove for supplying air having a large groove width is formed on the outer peripheral surface of the radial static pressure gas bearing 2. It is possible to prevent the radial static pressure gas bearing 2 from being deformed to lower the bearing performance by the gas pressure acting on the annular groove for use.

  Next, FIG. 2 shows a cross-sectional view of a hydrostatic gas bearing device according to the second embodiment of the present invention. The static pressure gas bearing device shown in the figure includes a rotating shaft 11, a flange 12 provided at one end of the rotating shaft 11, and an annular thrust bearing surface 13a facing the inner flange surface 12a of the flange 12. And a cylindrical static pressure gas bearing 13 having a radial bearing surface 13 b facing the outer peripheral surface of the rotating shaft 11, and a bearing housing 14 for housing the static pressure gas bearing 13. Is formed with a pressurized gas supply passage 15 for supplying pressurized gas to the annular grooves 16 and 17 for air supply formed on the outer peripheral surface of the static pressure gas bearing 13.

  Here, when the axial length of the static pressure gas bearing 13 is L, the air supply annular grooves 16 and 17 are formed on the outer peripheral surface of the static pressure gas bearing 13 with a groove width of, for example, 1 / 10L to 1 / 4L. ing. Further, if the radial thickness of the static pressure gas bearing 13 is T, the air supply annular grooves 16 and 17 are formed on the outer peripheral surface of the static pressure gas bearing 13 with a groove depth of, for example, 1 / 10T to 1 / 2T. ing.

  In such a configuration, the pressurized gas supplied from the pressurized gas supply passage 15 to the air supply annular grooves 16 and 17 passes through the inside of the static pressure gas bearing 13 and faces the inner flange surface 2 a of the flange 2. While ejecting from the thrust bearing surface 13a, it ejects from the radial bearing surface 13b facing the outer peripheral surface of the rotating shaft 11. At this time, the pressure distribution of the pressurized gas ejected from the radial bearing surface 13b becomes a substantially uniform pressure distribution in the axial direction of the static pressure gas bearing 13, so that the bearing performance of the static pressure gas bearing 13 is not greatly reduced. The axial length of the pressurized gas bearing 13 can be increased. Further, the mechanical strength of the static pressure gas bearing 13 is not greatly reduced unlike the case where an annular groove for supply of air having a large groove width is formed on the outer peripheral surface of the static pressure gas bearing 13. It is possible to suppress the deformation that lowers the bearing performance due to the gas pressure acting on the groove from occurring in the static pressure gas bearing 13.

It is an axial sectional view of the static pressure gas bearing device concerning a 1st embodiment of the present invention. It is an axial sectional view of a hydrostatic gas bearing device concerning a 2nd embodiment of the present invention. It is sectional drawing which shows an example of the conventional static pressure gas bearing apparatus. It is sectional drawing which shows the other example of the conventional static pressure gas bearing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotating shaft 2 Radial static pressure gas bearing 2a Radial bearing surface 3 Bearing housing 5 Pressurized gas supply path 6,7 Annular groove for air supply 11 Rotating shaft 12 Flange 13 Hydrostatic gas bearing 13a Thrust bearing surface 13b Radial bearing surface 14 Bearing Housing 15 Pressurized gas supply path 16, 17 Annular groove for air supply

Claims (2)

A cylindrical radial static pressure gas bearing having a radial bearing surface facing the outer peripheral surface of the rotary shaft, and pressurization for supplying pressurized gas to an air supply annular groove formed on the outer peripheral surface of the radial static pressure gas bearing In a static pressure gas bearing device comprising a bearing housing having a gas supply path,
A static pressure gas bearing device, wherein a plurality of the annular grooves for supplying air are provided on an outer peripheral surface of the radial static pressure gas bearing. A cylindrical shape having a rotating shaft, a flange provided at one end of the rotating shaft, an annular thrust bearing surface facing the inner flange surface of the flange, and a radial bearing surface facing the outer peripheral surface of the rotating shaft And a bearing housing having a pressurized gas supply passage for supplying pressurized gas to an air supply annular groove formed on the outer peripheral surface of the static pressure gas bearing. In
A static pressure gas bearing device comprising a plurality of the annular grooves for supplying air on an outer peripheral surface of the static pressure gas bearing.

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