JP2814656B2 - Hydrostatic gas bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The hydrostatic gas bearing of the present invention is used for supporting a rotating part of a precision machine tool or the like. It is intended to reduce the size and improve the rigidity of the bearing.

(Prior Art) Static pressure gas bearings that are incorporated in precision machine tools and the like and that support a rotating member such as a rotating shaft that rotates at a high speed and that is supported by the force of a compressed gas such as air have been widely used.

FIGS. 10 and 11 show a static pressure gas bearing described in Japanese Patent Publication No. 45-37683 as an example of such a conventionally known static pressure gas bearing.

In FIG. 10, reference numeral 1 denotes a bearing member having an inner peripheral surface having a cylindrical bearing surface 2, and a rotating shaft 3 as a rotating member is inserted inside the bearing member 1. At the four positions of the bearing surface 2 at the top, bottom, left and right, concave portions 4a, 4b, 5
The rotary shaft 3 is supported inside the bearing member 1 in a non-contact state by forming a, 5b and sending a compressed gas into each of the recesses 4a, 4b, 5a, 5b.

Of the four recesses 4a, 4b, 5a and 5b, the recesses 4a and 4b at two upper and lower positions are controlled via the first control throttle valve 6, and the recesses 5a and 5b at two right and left positions are controlled by the second control. Each is connected to a compressed gas supply source such as a compressor through a throttle valve 7.

The first and second control throttle valves 6 and 7 are provided with upper and lower recesses 4a and 4a so that the bearing surface 2 and the outer peripheral surface of the rotary shaft 3 are concentric.
b, or for adjusting the amount and pressure of the compressed gas to be sent to the left and right recesses 5a and 5b, for example, as shown in FIG.

A first port 9 provided in the center of one surface of a housing 8 constituting a first (second) control throttle valve 6 (7) and a recess 4a (5)
a), the second port 11 provided at the center of the other surface and the recess 4b (5b) are connected by the second supply pipe 12, respectively. A diaphragm 15 is provided at an intermediate portion of the housing 8, and the inside of the housing 8 is divided into a first chamber 13 on the first port 9 side and a second chamber 14 on the second port 11 side. A compressed gas is supplied to the first and second chambers 13 and 14 from a compressed gas supply source.

On the inner surface of the housing 8, first and second ports 9,
The position surrounding the opening of 11 is protruded inward over the entire circumference, and on both sides of the diaphragm 15, the first and second ports 9, 11 and the first and second chambers 13, Between them, first and second throttle channels 16 and 17 are formed, respectively.

Due to the above-described configuration, when the outer peripheral surface of the rotary shaft 3 and the bearing surface 2 are not concentric with each other based on the displacement of the rotary shaft 3, the first and second control throttle valves 6, 7 By the action, the amount and pressure of the compressed gas fed into the recesses 4a, 4b, 5a, 5b are appropriately adjusted, and the outer peripheral surface of the rotating shaft 3 and the bearing surface 2 are concentric.

For example, when the rotating shaft 3 is displaced downward in FIG. 11, the dimension of the bearing gap 18 between the outer peripheral surface of the rotating shaft 3 and the bearing surface 2 is small on the lower side and larger on the upper side. Along with this dimensional change, the pressure in the lower recess 4b (5b) increases, the pressure in the upper recess 4a (5a) decreases, and the second supply pipe 12 communicates with the recess 4b (5b). The pressure in the two ports 11 increases, and the pressure in the first port 9 communicated with the recess 4a (5a) by the first supply pipe 10 decreases.

As a result, the diaphragm 15 partitioning the first and second ports 9 and 11 is displaced upward, the second throttle channel 17 is widened, the first throttle channel 16 is narrowed, and the lower concave portion 4b (5b The amount and pressure of the compressed gas fed into the parentheses) increase, and the upper concave portion 4a
The amount and pressure of the compressed gas sent into (5a) decreases, and the rotating shaft 3 is pushed upward in FIG. 11, so that the displacement of the rotating shaft 3 is eliminated.

(Problems to be Solved by the Invention) However, the conventional hydrostatic gas bearing configured and operated as described above has the following problems.

That is, in the case of the conventional structure, as shown in FIG. 10, both the first and second control throttle valves 6, 7 and the recesses 4a, 4b, 5a, 5b
The first and second supply pipes 10, 12 for communicating with
Since the response of the flow rate control when the rotating shaft 3 is displaced is poor, self-excited vibration is easily generated by the compressed gas sent into the recesses 4a, 4b, 5a, 5b. Operation of a machine tool or the like incorporating a gas bearing cannot be stably performed.

The hydrostatic gas bearing of the present invention solves the above-mentioned problems.

(Means for Solving the Problems) A hydrostatic gas bearing according to the present invention includes a housing having a bearing surface, a plurality of pressure volumes formed in the bearing surface, and an elongated hole formed in an outer surface of the upper housing. A control throttle valve provided in the space, a distribution passage formed in the housing and communicating the control throttle valve with each of the pressure volumes, and a supply passage for communicating a compressed gas supply source with the space. An air flow path.

The control throttle valve includes a rectangular leaf spring and a pair of rectangular valve seat plates that sandwich the leaf spring.
A convex portion having a height smaller than the depth of the concave portion is formed at the center of the concave portion formed at the central portion of the surface of each valve seat plate facing the leaf spring, and the central portion of the convex portion is formed at the center of the concave portion. In addition, a through hole is formed to communicate a space existing between each valve seat plate and the leaf spring with the distribution channel.

(Operation) In the case of the hydrostatic gas bearing of the present invention configured as described above,
Compressed gas for supporting the rotating member is sent into the bearing gap through the control throttle valve and the pressure volume, and supports the rotating member in a non-contact state with the bearing member.

In the case of the hydrostatic gas bearing of the present invention, the control throttle valve is built in the housing, and the distribution flow path connecting the control throttle valve and the pressure volume section is shortened, so that the responsiveness of the control throttle valve is improved,
Self-excited vibration is less likely to occur, and the operation of the device incorporating the hydrostatic gas bearing can be performed in a stable state.

Further, the leaf spring and the valve seat plate constituting the control throttle valve are rectangular, and the space for accommodating the control throttle valve is elongated, so that a plurality of control throttle valves are installed in a small area. And the size of the hydrostatic gas bearing can be reduced.

(Example) Next, the present invention will be described in more detail while describing the illustrated example.

1 to 8 show an embodiment of the present invention. FIG. 1 is a cross-sectional view showing a thrust bearing portion cut along a line AA in FIG. 8, and FIG. 2 is formed on a thrust bearing surface. FIG. 1 is a view taken along the line BB of FIG. 1 showing the shape of the slit groove, and FIG.
FIG. 4 is a sectional view showing a radial bearing portion taken along line C of FIG.
FIG. 3 is a sectional view taken along the line DD in FIG. 3, FIG. 5 is a view taken along the line EE in FIG. 4, and FIG. 6 is an exploded perspective view of the control throttle valve. FIG. 7 is a view corresponding to a section taken along line FF of FIG. 6, showing an assembled state of the control throttle valve, and FIG. 8 is a view taken along the line GG of FIG. 1 showing an arrangement state of the control throttle valve. is there.

In FIG. 1, inner cylinders 22 each formed in a short cylindrical shape are shown.
The outer cylinder 23 is externally fitted and fixed. A cylindrical rotary member 24 is inserted inside the inner cylinder 22, and the inner surfaces of the flange pieces 25a and 25b fixed to both ends of the rotary member 24, the inner cylinder 22 and the outer cylinder 23, respectively. Bearing member 26 fixed to the end face of
a and 26b face each other. The housing 21 is composed of the inner cylinder 22, the outer cylinder 23, and the bearing members 26a and 26b.

Each of the bearing members 26a, 26b fixed to the end faces of these members 22, 23 in such a manner as to be sandwiched between the inner cylinder 22 and the outer cylinder 23 has respective outer surfaces as bearing surfaces 27a, 27b. Bearing surface
As shown in FIG. 2, slit grooves 28a and 28b, each of which is a pressure volume section, are formed of a plurality of concentric arc portions and a radiating portion connecting the plurality of concentric arc portions to each other, as shown in FIG. I have.

Each slit groove 28a, 28b is a distribution channel 29a, 29b, respectively.
And a control throttle valve 30a provided in the outer cylinder 23;
1 and a compressed gas supply source such as a compressor, and the compressed gas is fed into each of the slit grooves 28a and 28b so that the housing 21 supports the rotating member 24 in a non-contact state. .

That is, the compressed gas sent into each of the slit grooves 28a, 28b causes the bearing surfaces 27a, 27b and the flange pieces 25a, 2
A bearing gap is formed between the bearing member and the inner surface of the housing 5b, and the rotating member 24 rotates inside the inner cylinder 22 of the housing 21 so that the flange pieces 25a, 25b and the bearing members 26a, 26b come into contact with each other. I am doing it.

The control throttle valve 30a provided between the supply flow passage 31 and the distribution flow passages 29a, 29b communicating with the slit grooves 28a, 28b is the first and second control throttle valve 6, 7 in the above-described conventional structure. (10th ~
11), the amount of compressed gas supplied to both slit grooves 28a and 28b is adjusted, and the size of the bearing gap between the inner surface of the flange piece 25a and the bearing surface 27a is determined. Two
This is to prevent the size of the bearing gap between the inner surface of 5b and the bearing surface 27b from being largely different.

However, in the case of the control throttle valve used in the present invention, such a control throttle valve 30a is provided with a leaf spring 32 having a rectangular shape and a thickness of about 0.1 to 0.35 mm as shown in FIG. A pair of rectangular valve seat plates 37, 37 for holding the spring 32;
A control throttle valve 30a composed of these members 32 and 37 is mounted in a concave portion 33a which is a long hole-shaped space formed on the outer surface of the outer cylinder 23. .

In the case of the control throttle valve 30a for a static pressure gas bearing, the leaf spring 3
When the thickness of 2 is less than 0.1mm, leaf spring corresponding to pressure change
The movement of 32 becomes too sensitive, and the control by the control throttle valve 30a is not stabilized, and self-excited vibration is likely to occur. Conversely,
When the thickness of the leaf spring 32 exceeds 0.35 mm, the movement of the leaf spring 32 becomes excessively rough, and the control by the control throttle valve 30a is not performed much. For this reason, the thickness of the leaf spring 32 is limited to the above range.

Recesses 34, 34 are formed in the center of the surface of each of the valve seat plates 37, 37 facing the leaf spring 32, and the depth of each of the recesses 34, 34 is The protrusions 35 having a height dimension h (<d) smaller than the height dimension d are formed. Further, in the center of each convex portion 35, 35, each valve seat plate 37, 37 and a plate spring
32 and the distribution channels 29a, 29b
As shown in FIG. 7, through-holes 42, 42 having an inner diameter of about 1 to 3 mm are formed in order to communicate with. And each of these members
The opening of the concave portion 33a in which the control throttle valve 30a composed of 32 and 37 is mounted is closed by a cover plate 38. The cover plate 38 has a slit groove
A part of a distribution channel 29b communicating with 28b is formed, and a pair of distribution channels 29a and 29b are connected to the control throttle valve 30a from both sides.

If the inner diameter of the through hole 42 is less than 1 mm, each slit groove 2
The supply amount of the compressed gas to 8a and 28b is insufficient, and the support of the rotating member 24 is insufficient. Conversely, when the inner diameter of the through hole 42 exceeds 3 mm, the area of the surface of the convex portion 35 on the leaf spring 32 side decreases, and the aperture effect of the space 36 between the convex portion 35 and the leaf spring 32 decreases. As a result, the turbulence of the flow of the compressed gas increases, and the support of the rotating member 24 becomes unstable. For this reason, the inner diameter of each through hole 42 is set to 1 to 3 mm.

Further, on the bearing surface 39 provided on the inner peripheral surface of the inner cylinder 22, there are provided slit grooves 40, 40 of a "day" shape as shown in FIG. A total of eight pieces are formed for each piece. Then, as shown in FIGS.
Concave portions 33b to 3 which are long hole-shaped space portions formed on the outer peripheral surface of
Compressed gas is supplied to each of the slit grooves 40, 40 through the control throttle valves 30b to 30e including the rectangular leaf spring 32 and the valve seat plates 37, 37 built in 3e and the distribution channels 41, 41. I am doing it.

In the case of the hydrostatic gas bearing of the present invention configured as described above,
The compressed gas for supporting the rotating member 24 is supplied to each slit groove 28
a, 28b, 40, 40, are fed into the bearing gap between the inner surface of each flange piece 25a, 25b and the bearing surface 27a, 27b, and between the outer peripheral surface of the rotating member 24 and the bearing surface 39, A rotating member 24 is supported inside the housing 21 as a member in a non-contact state. When the rotating member 24 is displaced in the axial direction (the left-right direction in FIG. 1), the displacement is corrected by the action of the control throttle valve 30a. In this case, due to the operation of the control throttle valves 30b to 30e,
Correct this shift or tilt.

Further, in the case of the hydrostatic gas bearing of the present invention, a plurality (five) of control throttle valves 30a to 30e are connected to the housing 21 as shown in FIG.
The distribution flow paths 29a, 29b linking the control throttle valves 30a to 30e and the slit grooves 28a, 28b, 40, 40, which are pressure capacity sections,
Since 41 and 41 are shortened, the responsiveness of each control throttle valve 30a-30e is improved, self-excited vibration is less likely to occur, and the operation of the device incorporating the static pressure gas bearing can be performed in a stable state. You.

As shown in FIG. 9, circular recesses 19, 19 are formed on the outer surface of the housing 8, and circular control throttle valves 20, 20 are installed inside the recesses 19, 19, respectively. Recess
Adjacent recesses 1 to prevent interference between 19 and 19
It is necessary to make the interval between 9, 9 sufficiently large, so that the installation space for the control throttle valves 20, 20 becomes large and the hydrostatic gas bearing becomes large.

For this reason, in the case of the present invention, the leaf spring 32 and the valve seat plates 37, 37 constituting each of the control throttle valves 30a to 30e have a rectangular shape, and the concave portions 33a to 33e for accommodating the control throttle valves 30a to 30e are provided. As shown in FIG. 8, a plurality of control throttle valves 30a to 30e
Can be installed in a small area, and the size of the hydrostatic gas bearing can be reduced.

In order to control both the radial displacement and the thrust displacement by the control throttle valve, at least 3
In the case where two sets of radial bearings are provided in the axial direction in order to suppress the inclination of the rotating shaft 3, five control throttle valves are required.

The rotating shaft 3 is provided by a pair of thrust bearings shown in FIG.
In order to suppress the inclination of the thrust bearing, four control throttle valves for the thrust bearing are required.

(Effects of the Invention) Since the hydrostatic gas bearing of the present invention is constructed and operates as described above, self-excited vibration due to compressed gas for supporting the rotating member is unlikely to occur, and furthermore, a small hydrostatic gas bearing. Can be provided.

[Brief description of the drawings]

1 to 8 show an embodiment of the present invention. FIG. 1 is a cross-sectional view showing a thrust bearing portion cut along a line AA in FIG. 8, and FIG. 2 is formed on a thrust bearing surface. FIG. 3 is a BB view of FIG. 1 showing the shape of the slit groove, and FIG.
FIG. 4 is a cross-sectional view showing the radial bearing portion cut along the line C, FIG. 4 is a cross-sectional view taken along line DD of FIG. 3, and FIG. 5 shows the shape of a slit groove formed on the radial bearing surface. -E view,
6 is an exploded perspective view of the control throttle valve, FIG. 7 shows an assembled state of the control throttle valve, a view corresponding to a section taken along line FF of FIG. 6, and FIG. 8 shows an arrangement state of the control throttle valve. G in FIG.
FIG. 9 is a view similar to FIG. 8, showing a state in which a circular control throttle valve is arranged, FIG. 10 is a sectional view showing an example of a conventional hydrostatic gas bearing, FIG. FIG. 3 is a sectional view showing a control circuit using a control throttle valve. 1: bearing member, 2: bearing surface, 3: rotating shaft, 4a, 4b, 5a, 5b: recess, 6: first control throttle valve, 7: second control throttle valve, 8: housing, 9: No. 1 port, 10: first supply pipe, 11: second port, 12: second supply pipe, 13: first chamber, 14: second chamber, 15: diaphragm, 16: first throttle channel, 17: first Two throttle channels, 18: bearing gap, 19: recess, 20: control throttle valve, 21: housing, 22: inner cylinder, 23: outer cylinder, 24: rotating member, 25a, 25b: flange piece, 26
a, 26b: bearing member, 27a, 27b: bearing surface, 28a, 28b: slit groove, 29a, 29b: distribution channel, 30a, 30b, 30c, 30d, 30e:
Control throttle valve, 31: air supply flow path, 32: leaf spring, 33a, 33b, 33
c, 33d, 33e, 34: concave, 35: convex, 36: space, 37: valve seat plate, 38: lid plate, 39: bearing surface, 40: slit groove, 41: distribution channel, 42: through hole .

Claims (3)

(57) [Claims] 1. A housing having a bearing surface, a plurality of pressure volumes formed in the bearing surface, a control throttle valve provided in a slot-like space formed on an outer surface of an upper housing, and a housing inside the housing. And a distribution flow path that communicates the control throttle valve with each of the pressure volume parts, and an air supply flow path that communicates the compressed gas supply source with the space part. A plate-shaped leaf spring and a pair of rectangular valve seat plates sandwiching the leaf spring. The concave portion is formed at the center of the concave portion formed at the center of the surface of each valve seat plate facing the leaf spring. A convex portion having a height dimension smaller than the depth dimension of the valve member is formed, and a central portion of the convex portion communicates with a space existing between each valve seat plate and the leaf spring and the distribution channel. Hydrostatic gas bearing with holes. 2. The hydrostatic gas bearing according to claim 1, wherein a plurality of spaces are formed on an outer surface of the housing, and a control throttle valve is provided in each space. 3. The hydrostatic gas bearing according to claim 1, wherein the inner diameter of the through hole is 1 to 3 mm, and the thickness of the leaf spring is 0.1 to 0.35 mm.