JPH03282008A - Air spindle with damper - Google Patents

Abstract

PURPOSE:To restrict vibration by providing radial bearing surfaces and thrust bearing surfaces to a housing member so that they are opposed to a spindle, and providing a clearance possessing damper-oil between the midposition of the radial bearing surfaces in two places and the shaft part of the spindle. CONSTITUTION:On the upper and lower end faces of the inside peripheral surface of a housing 3, gas bearing elements 4, 4 made of porous material are fixed, and the inside peripheral surfaces of the gas bearing elements 4, 4 are used as radial bearing surfaces 5, 5, while the sides of these elements are used as thrust bearing surfaces 6, 6. A shaft part 8, flange parts 9, 9 of a shaft member 7 inserted inside the housing 3 are respectively opposed to the radial bearing surfaces 5, 5 and the thrust bearing surfaces 6, 6. At mid-position of the radial bearing surfaces in two places, a recessed groove 24 is formed over the full length of the periphery of the shaft part to obtain the oil-storage effect and the sealing effect, and damper-oil 19 is held in a clearance between the shaft part 8 and the groove. Since the damper is located close to the radial bearing surfaces and at the portion of high bearing rigidity, vibration due to surface- deflection can be restricted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The air spindle with a damper according to the present invention is used as a rotary support part of a rotary table for minute angle positioning, a precision machine, etc.

(Prior art) Gas bearings (air spindles), which support the rotating shaft using compressed gas, are often used in the rotating shaft support parts of precision instruments, etc.; When used in rotary support parts such as rotary tables and precision instruments, a damper is installed to prevent minute vibrations of the rotating shaft due to displacement.

Figures 5 and 6 show two conventionally used air spindles with dampers for use in such cases.
An example is shown.

First, in the case of the structure of the first example shown in FIG. 5, a damper unit 2 is assembled to the end of a normal air spindle 1, thereby forming an air spindle with a damper.

Of these, the air spindle 1 has two gas bearing elements 4.4 made of a porous material in a circular tube shape fixed to the inner peripheral surface of the housing 3, and the inner peripheral surface of each gas bearing element 4.4 is fixed to the inner peripheral surface of the housing 3. The bearing surface 5.5 is defined as a thrust bearing surface 6.6, and the side surface of each gas bearing element 4.4 is defined as a thrust bearing surface 6.6. The outer peripheral surface of a part of the shaft portion 8 of the shaft member 7 rotatably inserted into the inside of the housing 3 is opposed to the radial bearing surface 5.5.

Furthermore, flange portions 9.9 having a larger diameter than the shaft portion 8 are provided at both upper and lower ends of the shaft member 7, and each flange portion 9.9
The side surface of the bearing face 6.6 faces the thrust bearing surface 6.6.

A compressed gas supply port 10 is provided on the outer peripheral surface of the housing 3, and the compressed gas fed into each gas bearing element 4.4 through the supply port 10 is supplied to the radial bearing surface 5.5 and the thrust bearing surface 6.4. 6 toward the outer peripheral surface of the shaft portion 8 and the side surface of the flange portion 9.9, and the shaft member 7 is rotatably supported inside the housing 3. The gas ejected into the housing 3 is discharged through the exhaust port 26 opened between the rear gas bearing elements 4.4, the outer periphery of the gap between the thrust bearing surface 6.6 and the flange portion 9.9, and as described below. The liquid is discharged to the outside of the housing 3 from the discharge port 37 provided in the case 13.

Further, a rotor 12 is fixed to the outer circumferential surface of the drive shaft portion 11 that protrudes from the end surface of the shaft member 7, and the inner circumferential surface of the case 13 fixed to the end surface of the housing 3 faces the outer circumferential surface of the rotor 12. A stator 14 is fixed to the portion where the shaft member 7 is rotated, thereby forming an electric motor 15 for rotationally driving the shaft member 7.

Furthermore, a damper shaft 16 is fixed to the end surface of the drive shaft portion 11.
protrudes outside the case 13, and the damper unit 2 is provided around the damper shaft 16.

This damper unit 2 includes a disc 17 fixed to the outer peripheral surface of the damper shaft 16, a holder 18 fixed to the outer surface of the case 13 surrounding the date plate 17, and It consists of a damper oil 19 interposed between the inner surface and the outer surface of the disk 7. Magnetic fluid seals 2o and 2° are provided between the inner peripheral edges of the openings at both ends of the holder 18 and the outer peripheral surface of the damper shaft 1d, respectively, to prevent leakage of the damper oil 19.

In the case of the second example shown in FIG. 6, damper oil 19 is stored in an oil case 21 fixed to the lower surface of the case 13, and a wing piece 22 fixed to the lower end of the damper shaft 16 is stored.
is rotated within the damper oil 19 to form one damper unit 2a.

A seal member 23 is provided between the opening of the case 13 and the outer peripheral surface of the damper shaft 16 to prevent leakage of the damper oil 19.

In the case of each damper-equipped air spindle configured as described above, the shaft member 7 rotates based on energization of the electric motor 15, and the damper unit 2.2a absorbs the minute vibrations that occur due to this rotation. do.

(Problems to be Solved by the Invention) However, in the case of the conventional air spindle with a damper configured as described above, the following disadvantages occur.

That is, in any structure, the damper unit 2
．． 2a is provided in a part far away from the flange portion 9.9 in the axial direction, so that when the shaft member 7 is rotated, the disk 17 and blade pieces of the damper unit 2.2a due to the rotation Damper oil 1 caused by surface runout of 22
The force shearing 9 is applied to the air spindle 1 as a moment load.

Air spindle 1 that supports shaft member 7 by gas pressure
In the case of , the bearing rigidity and load capacity are much smaller, about 1/1 of that of rolling bearings for boat fishing, so when a large moment load acts on the damper unit 2.2a as described above, this load is As a result, the shaft member 7 swings around, making it impossible to maintain rotational accuracy.

In addition, in the case of the second example structure shown in Fig. 6, the damper oil 1
In order to prevent leakage, it is necessary to use a vertical type as shown in the figure. If the sealing performance is improved by the sealing member 23 and it can be used horizontally, the frictional resistance between the sealing member 23 and the damper shaft 16 will increase, making it difficult to maintain the rotational positioning accuracy of the shaft member 7. I end up.

Furthermore, in either structure, since the damper unit 2.2a is provided to protrude from the air spindle 1, it is difficult to reduce the size and weight of the damper-equipped air spindle.

The damper-equipped air spindle of the present invention eliminates the above-mentioned disadvantages.

(Means for Solving the Problems) The air spindle with a damper of the present invention has a radial bearing surface provided on the inner peripheral surface of the housing member, a thrust bearing surface provided on the side surface of the housing member, and the A shaft part that forms a part of the shaft member inserted into the inside of the housing member and has an outer peripheral surface facing the radial bearing surface, and a shaft part that is provided on a part of the outer peripheral surface of the shaft member and has a side surface facing the thrust surface. It has a flange portion facing the bearing surface.

In the case of the damper-equipped near spindle according to claim 1, a part of the inner circumferential surface of the housing member is located between two radial bearing surfaces, and a part of the shaft member is located opposite to this position. Damper oil is held in the radial gap provided between the

Moreover, in the case of the air spindle with a damper described in claim 2, damper oil is held in a radial gap provided between the flange portion and the housing member.

(Function) In the air spindle with a damper of the present invention configured as described above, the damper is provided in a portion with high bearing rigidity close to the radial bearing surface, so that vibrations due to surface runout of the damper can be suppressed.

Furthermore, since the damper does not protrude outward in the axial direction from the flange portion, it is easy to reduce the size and weight of the air spindle with the damper.

(Example) Next, the present invention will be explained in more detail while explaining the illustrated embodiment.

FIG. 1 shows a first embodiment of an air spindle with a damper according to the present invention.

A gas bearing element 4.4 made of a porous material in a circular tube shape is fixed to the upper and lower ends of the inner peripheral surface of the housing 3, respectively.The housing member 34 connects the housing 3 and the gas bearing element 4.4. It is equipped with The inner peripheral surface of each gas bearing element 4.4 is a cylindrical radial bearing surface 5.5, and the side surface of each gas bearing element 4.4 is a planar thrust bearing surface 6.6. The outer peripheral surface of a part of the shaft portion 8 of the shaft member 7 rotatably inserted into the inside of the housing 3 is opposed to the radial bearing surface 5.5. Further, at both upper and lower ends of the shaft member 7, flange portions 9 and 9 having a larger diameter than the shaft portion 8 are provided.
, and the side surface of each flange portion 9.9 faces the thrust bearing surface 6.6.

A compressed gas supply port 10 is provided on the outer peripheral surface of the housing 3, and the compressed gas sent into each gas bearing element 4.4 through the supply port 10 is supplied to the radial bearing surface 5.5 and the thrust bearing surface 6.4. 6 toward the outer peripheral surface of the shaft portion 8 and the side surface of the flange portion 9.9, and the shaft member 7 is rotatably supported inside the housing 3 by a hydrostatic gas bearing.

In the middle part of the inner peripheral surface of the housing 3, between the two radial bearing surfaces 5.5, there are a plurality of grooves 24.24.
is formed over the entire circumference of the inner peripheral surface. This groove 24.24 has an oil storage effect and a sealing effect.

A radial gap 25 is provided between the groove 24, 24 forming portion of the inner circumferential surface of the housing 3 and the outer circumferential surface of the intermediate portion of the shaft portion 8, and this gap 25 and the groove 24 are filled with oil, It holds damper oil 19 such as grease. Incidentally, grooves 24 and 24 may be provided on at least one of the outer circumferential surface of the shaft portion 8 and the inner circumferential surface of the housing 3.

Magnetic fluid seals 20 and 20 are provided at two positions on the inner peripheral surface of the housing 3 sandwiching the gap 25, respectively, to prevent leakage of the damper oil 19 to the outside of the gap 25. In addition, the magnetic fluid used for the magnetic fluid seal 20.20 is
It may also be used as damper oil 19.

Also, in a part of the housing 3, each magnetic fluid seal 20.2
0 and the gas bearing element 4.4, discharge ports 26.26 are opened respectively, and the radial bearing surface 5.
．． The compressed gas ejected from 5 into the housing 3 can be freely discharged.

The operation of rotatably supporting the shaft member 7 using the damper-equipped air spindle of the present invention constructed as described above is similar to that of the conventional damper-equipped air spindle described above.

However, in the case of the air spindle with a damper of the present invention, the shaft portion 8
The machining accuracy of the damper, which consists of the outer circumferential surface of the housing 3 and the inner circumferential surface of the housing 3, can be easily manufactured to the same level as the machining accuracy of a gas bearing, and the circumferential clearance of the damper can be made uniform to prevent oil film fluctuations. /h can be written. Also, a pair of gas bearing elements 4.4
By interposing the damper oil 19 between the shaft portion 8 and the groove 24 . Since this damper is provided, the vibration of the shaft member 7 is not worsened, and the vibration absorption performance in the radial direction by this damper is excellent.

Furthermore, since the damper does not protrude significantly from the air spindle 1, it becomes easy to reduce the size and weight of the air spindle with the damper.

Next, FIG. 2 shows a second embodiment of the present invention.

In the case of this embodiment, the groove 24.
There are discharge ports 26 and 26 at the positions sandwiching the 24 forming part, respectively.
a pair of grooves 27.2 each extending circumferentially, leading to
7 is directly formed without passing through the magnetic fluid seal 20.20, so that the compressed air blown out from the radial bearing surface 5.5 of the gas bearing element 4.4 is discharged through each groove 27.27. . The damper oil 19 uses an oil that can obtain high surface tension in order to prevent oil leakage.

Further, a rotor 12 is fixed to the outer circumferential surface of the drive shaft portion 1'1 projected from the end surface of the shaft member 7, and the outer circumferential surface of the rotor 12 is fixed to the inner circumferential surface of the case 13 fixed to the end surface of the housing 3. A stator 14 is fixed to a portion facing the shaft member 7, thereby forming an electric motor 15 for rotationally driving the shaft member 7. In addition, the lower thrust bearing surface 6 and the lower flange portion 9
The compressed air discharged from the thrust bearing gap between
From the discharge port 36 provided at the lower end of the case 13 to the case 13
Expelled outside.

The other configurations and operations are the same as those of the above-described first embodiment, so the same parts are given the same reference numerals and redundant explanations will be omitted.

Next, a third embodiment shown in FIG. 3 will be described.

In the case of this embodiment, a damper wall portion 28 having a larger diameter than both ends of the outer circumferential surface of the flange portion 9 is formed at the middle portion of the outer circumferential surface of the flange portion 9 provided at the upper end of the shaft member 7, and This damper wall portion 28 is surrounded by a short damper cylinder 29 fixed to the upper end surface.

Magnetic fluid seals 20.20 are provided at two positions on the inner circumferential surface of the damper short cylinder 29 at positions sandwiching the damper wall 28, and a gap between the two magnetic fluid seals 20.20 is provided. Damper oil 19 is sealed in a certain space. The housing part 34 therefore comprises a housing 3, a gas bearing element 4.4, a short damper cylinder 29 and a magnetic fluid seal 20.20. In this embodiment, the damper short cylinder 29 and the magnetic fluid seal 20.
There is no concave groove on the side surface of the damper 20, and the outlet 26 for discharging compressed air is located not only in the middle of the housing 3 but also in the base end (lower end in FIG. 3) of the short damper cylinder 29. There is also a

In the case of this embodiment, vibrations in both the vertical direction and the radial direction are absorbed by the short damper cylinder 29, the magnetic fluid seal 20, 20, both upper and lower side surfaces and outer peripheral surface of the damper wall 28, and the damper oil 19. do. Also, unlike the first to second embodiments, the damper is composed of a pair of gas bearing elements 4.4.
Although the stiffness of the damper part is slightly lower because it is not provided in the middle position, since the distance between the gas bearing element 4.4 and the damper is closer than in the case of the conventional structure described above, the deflection of the shaft member 7 is reduced. There is no deterioration, and it is possible to obtain practically sufficient vibration absorption performance. Furthermore, the damper is provided externally to facilitate maintenance of the damper.

The other configurations and operations are the same as those of the first embodiment described above, so the same parts are given the same reference numerals and redundant explanations will be omitted.

Next, a fourth embodiment shown in FIG. 4 will be described.

In the case of this embodiment, a groove 31 is formed on the upper surface of the damper receiving member 30 fixed to the upper end surface of the housing 3.
A large number of small grooves 32.3 are formed on the outer circumferential surface, inner circumferential surface, and bottom surface of 1.
2 is formed. The housing part 34 therefore comprises the housing 3, the gas bearing element 4.4 and the damper receiving part 30.

On the other hand, a first flange portion 35 having a larger diameter than the shaft portion 8 is provided at the upper end of the shaft member 7, and at the upper end of this first flange portion 35, a base of a damper ring 33 having a rectangular cross section is provided. The end of the damper ring 33 is fixed, and the tip of the damper ring 33 is inserted into the groove 31. Therefore, the upper flange portion 9
includes a first flange portion 35 and a damper ring 33.

Damper oil 19 is interposed between the inner surface of the groove 31 and the outer surface of the tip end of the damper ring 33 to form a damper mechanism. In this embodiment, the damper ring 33
It absorbs vibrations on the outer peripheral surface and inner peripheral surface of the damper ring 33, and also absorbs vibrations on the lower surface of the damper ring 33. Note that a small groove 32 is formed on at least one of the inner surface of the groove 31 and the damper ring 33.
may be provided.

Furthermore, a rotor 12 is fixed to the outer circumferential surface of the drive shaft portion 11 that protrudes from the end surface of the shaft member 7, and the inner circumferential surface of the case 13 fixed to the end surface of the housing 3 is opposed to the outer circumferential surface of the rotor 12. A stator 14 is fixed to the portion where the shaft member 7 is rotated, thereby forming an electric motor 15 for rotationally driving the shaft member 7. The outlet 26 for discharging compressed air is provided not only at the middle part of the housing 3 but also at the base end of the damper receiving member 30 (lower end in figure S4).

The other configurations and functions are the same as those of the third embodiment described above, so the same parts are given the same reference numerals.
Omit duplicate explanations.

In each embodiment, the size of the gap (radial direction gap and thrust direction gap) for interposing the damper oil 19 is about 5 to 10 μm, which is the same as the radial bearing gap and thrust bearing gap of the air spindle 1. The size of the gap for interposing the damper oil 19 is adjusted as appropriate depending on the viscosity of the damper oil 19 used. Further, the static pressure gas bearing may be of a porous type, a multi-hole type, or a surface drawing type.

Further, the housing member 34 and the shaft member 7 may be composed of one member or may be composed of a plurality of members.

(Effects of the Invention) The air spindle with a damper of the present invention is configured and operates as described above, but in order to suppress the vibration caused by shearing the damper oil due to the surface runout caused by the rotation of the damper with high bearing rigidity, the damper is Not only is it possible to improve the accuracy of precision machines, etc. incorporating the air spindle with the damper, but it is also easier to reduce the size and weight of the air spindle with the damper.

[Brief explanation of drawings]

Fig. 1 shows the first embodiment of the present invention, Fig. 2 shows the second embodiment, Fig. 3 shows the third embodiment, Fig. 4 shows the fourth embodiment, and Fig. 5 shows the fourth embodiment. FIG. 6 is a sectional view showing a first example of the conventional structure, and FIG. 6 is a sectional view showing a second example. 1: Air spindle, 2.2a: Damper unit, 3
Housing, 4: Gas bearing element, 5 Ni radial bearing surface,
6: Thrust bearing surface, 7: Shaft member, 8: Shaft, 9: Flange, 10: Supply port, 11, Drive shaft, 12: Rotor, 13/Case, 14: Stator, 15: Electric motor,
16 Damper shaft, 17: Disc, 18: Holder, 19: Damper oil, 20: Magnetic fluid seal, 21, Ni oil case, 22: Wing piece, 23 Seal member, 24 Concave groove, 25
: Gap, 26: Discharge port, 27: Concave groove, 28: Damper wall, 29: Short cylinder for damper, 30. Damper receiving member, 3
1: Concave groove, 32: Small concave groove, 33. Damper ring, 34
: Housing member, 35: First flange part, 36.3
7: Outlet.

Claims (2)

[Claims] (1) A radial bearing surface provided on the inner peripheral surface of the housing member, a thrust bearing surface provided on the side surface of the housing member, and a part of the shaft member inserted inside the housing member, An air spindle having a shaft portion with an outer circumferential surface facing the radial bearing surface, and a flange portion provided on a part of the outer peripheral surface of the shaft member and having a side surface facing the thrust bearing surface, Damper oil is held in a radial gap provided between a part of the inner circumferential surface of the housing member between the two radial bearing surfaces and a part of the shaft member facing the two radial bearing surfaces. Air spindle with damper. (2) a radial bearing surface provided on the inner peripheral surface of the housing member, a thrust bearing surface provided on the side surface of the housing member, and a part of the shaft member inserted inside the housing member; and an air spindle having a shaft portion having an outer peripheral surface facing the radial bearing surface, and a flange portion provided on a part of the outer peripheral surface of the shaft member and having a side surface facing the thrust bearing surface, An air spindle with a damper retaining damper oil in a radial gap provided between the flange portion and the housing member.