JPH02209621A - Pneumatic bearing spindle with pumping mechanism - Google Patents

Abstract

PURPOSE:To prevent a bearing surface from being degraded as well as to restrain air from leaking to a lesser extent by providing a non-contact rotating joint not in a radial bearing surface but in the inner walls of a thrust plate and a rotor when air is charged to or exhausted from a rotating section. CONSTITUTION:When air is charged to a charging port 12, pressure is transferred to a charging groove 13. Since the charging groove 13 is sealed by the minute gaps of non-contact seals 14a and 14b, the pressure is transferred to the charging hole 7b of the thrust plate 2b. Successibly, the pressure is transferred to a cylinder 8 on a rotating section 20 through the charging hole 7c of the rotor 3 and the charging hole 7a of a thrust plate 2a. The rotating section 20 can be rotated with no friction because of the non-contact seals 14a and 14b, air can thereby be charged even when rotating is kept on. This constitution eliminates the need to perform any rotating joint like work for the rotating section, a bearing surface can be widened, no stiffness is thereby degraded. In addition, the non-contact seals are arranged not at the outer circumference of the rotating section, but at the inner wall surface, air thereby leaks to a lesser extent.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a gas bearing spindle with an air supply/exhaust mechanism that enables air supply and vacuum to pneumatic equipment on a rotating part during rotation, and particularly to The present invention relates to a gas bearing spindle with an air supply/exhaust mechanism that allows air to be supplied to or exhausted from a rotating part without adversely affecting the rigidity of the gas bearing by providing a contact rotary joint.

[Prior Art] Conventionally, as a gas bearing spindle that can supply and exhaust air to pneumatic equipment on a rotating part, as shown in FIG. There is a known structure in which a mechanism equivalent to a rotary joint is provided in the housing 25 and air is supplied or exhausted through a hole 27 provided in the housing 25 and a hole 28 provided in the rotating part. 62-218889, etc.).

[Problems to be Solved by the Invention] However, in the conventional example described above, since the radial bearing portion serves as a joint, there are the following drawbacks.

1) If the housing shape is the same, the bearing area will be smaller and the rigidity will be lower.

2) When air is supplied to the hand section 11, air also flows into the exhaust groove 29, increasing the pressure in the exhaust groove and reducing the rigidity due to the back pressure.

3) Processing of the housing becomes complicated.

In view of these problems of the prior art, an object of the present invention is to increase the rigidity of the bearing and to eliminate the need for complicated machining of the housing in a gas bearing spindle with an air supply/exhaust mechanism.

[Means for Solving the Problem] In order to achieve the above object, the present invention includes a rotating part including a spindle part and a thrust plate fixed to the spindle part, and a rotating part that includes a spindle part and a thrust plate fixed to the spindle part, In a gas bearing spindle equipped with a gas bearing that supports in the direction, a non-contact rotary joint is configured between the inner wall of the rotating part and a member facing the rotating part, and a hole provided in the member and communicating with the outside, Rotating joint,
Air is supplied to or exhausted from the rotating part through holes provided in the rotating part.

[Function] In this configuration, supply and exhaust to and from the rotating part are performed via a non-contact rotary joint, but this joint is provided on the inner wall surface of the rotating part, which has a smaller diameter than the radial bearing surface, and the seal part of the joint has a small diameter. Therefore, air supply and exhaust can be performed with less air leakage from the joint than in the past.

In addition, since the radial bearing surface is not processed for a joint, the rotating part is supported with high rigidity by a bearing surface that is larger than before. Furthermore, since the bearing surface and the joint are separate and independent, supply and exhaust can be carried out without any influence of back pressure on the bearing section.

[Example] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a sectional view of an air spindle with a motor according to an embodiment of the present invention. In the figure, 1 is a housing of a hydrostatic gas bearing, 2a and 2b are thrust plates, and 3 is a rotor (spindle part).
b is connected to the rotor 3 with bolts or the like to form a rotating part 20.

22 is a cylindrical radial gas bearing, 23a.

23b is an annular thrust gas bearing, 21 is an air supply hole, and the pressurized gas supplied from the air supply hole 21 is applied to the radial bearing 22, the rotor 3, the thrust bearings 23a, 23h, and the thrust plates 2a, 2b. A gas film is blown out in the gap and supports the rotating part 20 under static pressure in the radial direction and the thrust direction. 4 is a motor housing, 5 is a motor rotor, and 6 is a stator. 8 is a cylinder, 9 is a measurement head of the encoder, 10 is a disk of the encoder, 11 is a subaezer, and 17 is an air supply tower located at the center of the bearing. 7a, 7b are thrust plates 2a, 2
7c is an air supply hole provided in the rotor; 12 is an air supply hole provided in air supply tower 17; 13
are air supply grooves provided in the air supply tower 17, 14a, 14
b is a non-contact seal formed by a minute gap formed between the thrust plate 2b and the air supply tower 17, and 15 is an exhaust hole. When air is supplied to the air supply hole 12, the pressure is transmitted to the air supply groove 13, but since the air supply groove 13 is sealed by the small gap between the non-contact seals 14a and 14b, the pressure is transferred to the air supply hole 7b of the thrust plate 2b. , the rotating part 2 through the air supply hole 7c of the rotor 3 and the air supply hole 7a of the thrust play h2a.
0 to cylinder 8 above. Therefore, since the non-contact seals 14a and 14b allow the rotating portion to rotate without friction, air can be supplied even during rotation.

According to this configuration, the bearing part does not require processing similar to a rotary joint, so the bearing area can be increased, and since it is not affected by air supply to the rotating part, it has improved rigidity. It is possible to supply air to the cylinder 8 and the like. Also,
The gap area of a non-contact seal is approximated by (amount of gap) x (center diameter of seal part) x π, so compared to the conventional example where a non-contact seal is provided on the outer periphery of the rotating part (rotor), If it is provided on the inner wall surface of the rotating part as in this embodiment, the amount of air leakage will be smaller.

In this embodiment, a case has been described in which air is supplied to the cylinder 8, etc., but conversely, air may be evacuated using a vacuum pump or the like for a vacuum chuck or the like.

In addition, in Figure 1, the non-contact seal is a thrust brake)-2
b, but instead of this, the air supply tower 17 may be extended and provided on the rotor 3 or the thrust plate 2a.

Further, as shown in FIG. 3, a groove may be provided in the inner peripheral portion of the thrust plate 2b, and an air supply hole may be provided in the opposing tower 17.

[Effects of the Invention] As explained above, according to the present invention, by providing a non-contact rotating joint on the inner wall of the thrust plate or rotor (spindle portion) instead of on the radial bearing surface, it is possible to That is, air can be supplied to the rotating part or exhausted by vacuum without reducing the rigidity.

Furthermore, in the non-contact seal of a non-contact rotary joint where air leakage is inevitable, the gap area that is the cause of the air leakage is (
Since it is approximated by (gap amount) x (seal diameter) x π, the present invention in which a non-rotating joint is provided on the inner wall of the rotating part can reduce the seal diameter and reduce the gap area compared to the conventional technology in which the non-rotating joint is provided on the radial bearing surface. Since it can be made smaller, the amount of gap air leakage can be reduced when the spacing is the same.

Furthermore, even if the diameter of the rotating part or the diameter of the bearing becomes large, the inner wall of the rotating part can be made small, and the amount of air leakage from the joint part can always be kept small.

Furthermore, even when there is no need for supply/exhaust, it can be used as a normal gas bearing of the same size, and there is no need to process the housing (bearing part) for supply/exhaust.
The manufacturing cost is almost the same as the conventional one, as only the drilling of holes in the thrust plate and rotor is added.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an air spindle with a motor according to the present invention, FIG. 2 is a sectional view of a conventional gas bearing spindle,
FIG. 3 is a partial sectional view showing a modification of the device shown in FIG. 1. 1: Gas bearing housing, 2a, 2b; // Thrust plate, 3
: 〃 Rotor, 4: Motor housing, 5; Motor rotor, 6: Motor stator, 7a, 7b, 7c: Air supply hole, 8 Niji cylinder, 9: Encoder measurement head, 1O: Encoder disk, 11 Ni spacer, 12: Air supply hole, 13: Air supply groove, 14a, 14b: Non-contact seal, 15: Exhaust hole, 17: Air supply tower 20: Rotating part, 21: Gas bearing air supply hole, 22 Niradial bearing, 23a, 23b: Thrust bearing.

Claims (1)

[Claims] (1) A gas bearing spindle including a rotating part including a spindle part and a thrust plate fixed to the spindle part, and a gas bearing that supports the spindle part and the thrust plate in the radial direction and the thrust direction. Alternatively, a first hole opening in the inner wall of the spindle portion, and an annular groove facing the inner wall with a small gap therebetween and at a position opposite to the opening of the first hole; A member provided with a second hole that communicates the annular groove with the outside, and air is supplied to or exhausted from the rotating part through the first and second holes. Gas bearing spindle with supply and exhaust mechanism.