JP2002039181A - Static pressure gas bearing spindle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent, using a simple means, fragments of a bearing sleeve from scattering even if the sleeve is chipped when exerted with great impact on contact with a bearing. SOLUTION: The static pressure gas bearing spindle comprises a main spindle 1, a journal bearing part 7 for rotatably and radially supporting the main spindle 1 against housings 5 and 6, and thrust bearing parts 8 and 9 positioned in opposite relationship on both sides of a thrust plate 2 provided collectively with the main spindle 1, the thrust bearing parts axially supporting the main spindle 1. A compressed gas is ejected into the journal bearing part 7 and the thrust bearing parts 8 and 9 whereby the main spindle 1 is kept out of contact. The journal bearing part 7 opposite to the main spindle 1 is formed from a self- lubricating brittle material such as graphite or ceramics, and a closure means such as a wall 30 is provided to prevent exposure of the journal bearing part 7.

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 spindle, for example, a hydrostatic gas which is incorporated in a hole drilling machine, a precision processing machine, an electrostatic coating machine, etc., and in which a main shaft is supported in a non-contact manner by a hydrostatic gas bearing. Related to bearing spindle.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional example of a hydrostatic gas bearing spindle using an air turbine as a driving means. This spindle rotates the main shaft 1 by blowing compressed air to a plurality of concave portions 3 provided on the outer periphery of a thrust plate 2 of the main shaft 1 from a turbine nozzle 4 provided at a portion facing the concave portions 3. It is.

A main shaft 1 and a thrust plate 11 connected to the main shaft 1 are rotated in a non-contact manner with respect to the housings 5 and 6 by journal bearings 7 and thrust bearings 8 and 9 formed in the housings 5 and 6. It is freely supported.

The journal bearing portion 7 and the thrust bearing portion 8 are formed by shrink-fitting, press-fitting or bonding a bearing sleeve 10 made of a brittle material such as graphite having excellent self-lubricating properties to a substantially cylindrical housing 5. It is configured to be fitted and fixed by appropriate means such as. Similarly, the thrust bearing portion 9 is formed by mounting a bearing plate 11 made of a brittle material having excellent self-lubricating properties, such as graphite, on a circular lid-shaped housing 6 integrally joined to the end of the housing 5. It is configured to be fitted and fixed by appropriate means such as fitting, press-fitting or adhesion. The bearing sleeve 10 and the bearing plate 1 of the journal bearing 7 and the thrust bearings 8 and 9
1, a plurality of fine journal bearing nozzles 12 and thrust bearing nozzles 13 and 14 are provided.

[0005] The compressed air supplied from the air supply port 15 is supplied to the circumferential grooves 19 and 20 through the air passages 16, 17 and 18, and from the journal bearing nozzle 12 of the journal bearing portion 7 of the bearing sleeve 10. The journal is jetted onto the bearing surface, and the main shaft 1 is radially supported by the journal bearing portion 7.

On the other hand, the bearing sleeve 1 extends from the circumferential groove 19.
The thrust bearing nozzle 13 is jetted to the bearing surface of the thrust bearing portion 8. The compressed air supplied from the air supply port 15 is also supplied from the air passage 16 to the circumferential groove 21,
It is jetted from the thrust bearing nozzle 14 of the bearing plate 11 to the bearing surface of the thrust bearing 9. Thus, the main shaft 1 is axially supported by the thrust bearing portions 8 and 9.

A fixing ring 22 is fixed to the housing 5 by an appropriate means such as shrink fitting, press fitting or bonding. Each of the recesses 3 of the thrust plate 2 is
A plurality of turbine nozzles 4 which are opened substantially tangentially along the inner periphery of the fixing ring 22 at a portion opposed to the above, penetrate and form an air turbine.

The compressed air supplied from the air supply port 23 passes through the air passages 24 and 25 and the circumferential groove 26 from the turbine nozzle 4 of the fixed ring 22 to the thrust plate 2 of the main shaft 1.
Are ejected substantially tangentially toward the concave portion 3 of FIG. The jetted compressed air applies a rotational force to the main shaft 1 to generate an exhaust port 2.
7 is discharged to the outside of the housing 5. A tool or a work is attached to an end (the right end in the figure) of the main shaft 1, and operations such as machining and inspection are performed.

FIG. 6 shows another conventional example of a hydrostatic gas bearing spindle using an electric motor as a driving means. Since the basic configuration of this hydrostatic gas bearing spindle is the same as that of the spindle of FIG. 5, the same parts are denoted by the same reference numerals.

A main shaft 1 and a thrust plate 2 connected to the main shaft 1 are rotated in a non-contact manner with respect to the housings 5 and 6 by journal bearings 7 and thrust bearings 8 and 9 formed on the housings 5 and 6. It is freely supported.

The journal bearing portion 7 and the thrust bearing portion 8 are formed by shrink-fitting, press-fitting or bonding a bearing sleeve 10 made of a brittle material such as graphite having excellent self-lubricating properties to a substantially cylindrical housing 5. It is configured to be fitted and fixed by appropriate means such as. Similarly, the thrust bearing portion 9 is formed by mounting a bearing plate 11 made of a brittle material having excellent self-lubricating properties, such as graphite, on a circular lid-shaped housing 6 integrally joined to the end of the housing 5. It is configured to be fitted and fixed by appropriate means such as fitting, press-fitting or adhesion. The bearing sleeve 10 and the bearing plate 1 of the journal bearing 7 and the thrust bearings 8 and 9
1, a plurality of fine journal bearing nozzles 12 and thrust bearing nozzles 13 and 14 are provided.

The compressed air supplied from the air supply port 15 is supplied to the circumferential grooves 19 and 20 via the air passages 16, 17 and 18, and from the journal bearing nozzle 12 of the journal bearing portion 7 of the bearing sleeve 10. The journal is jetted onto the bearing surface, and the main shaft 1 is radially supported by the journal bearing portion 7.

On the other hand, the bearing sleeve 1 extends from the circumferential groove 19.
Compressed air is ejected from the thrust bearing nozzle 13 of No. 0 to the bearing surface of the thrust bearing portion 8. The compressed air supplied from the air supply port 15 is also supplied to the circumferential groove 21 from the air passage 16 and is jetted from the thrust bearing nozzle 14 of the bearing plate 11 to the bearing surface of the thrust bearing 9. Thus, the main shaft 1 is axially supported by the thrust bearing portions 8 and 9.

A stator (stator) 28 is disposed near the center of the housing 5, and a motor is constituted by a rotor (rotor) 29 formed at a position corresponding to the main shaft 1. In this electric motor, a rotating force is applied to the main shaft 1 on which the rotor 29 is formed by energizing the stator 28. A tool or a work is attached to an end (the right end in the figure) of the main shaft 1, and operations such as machining and inspection are performed.

In the above-mentioned conventional example, a self-contained throttle-type hydrostatic gas bearing in which the bearing sleeve 10 and the bearing plate 11 are formed of a material having no air permeability and a fine nozzle for supplying a compressed gas to the bearing gap is provided. Although an example of application is shown, the bearing sleeve 10 and the bearing plate 11 are formed of porous graphite or ceramic having air permeability, and a porous throttle type static pressure for supplying a compressed gas through fine pores of a porous material. Gas bearings have been used as well.

[0016]

By the way, in the case of a hydrostatic gas bearing spindle in which a journal bearing portion 7 is formed at the leading end side of the main shafts of the housings 5 and 6, since the housing shape can be simplified, FIGS. As shown, a structure in which a bearing sleeve 10 is exposed on the front end surface of a housing 5 (in the drawing,
(Indicated by an exposed portion a). In addition, brittle materials such as graphite having excellent self-lubricating properties have been recently awarded for the bearing sleeve 10 in order to improve seizure resistance at the time of contact with the bearing.

However, a brittle material such as graphite is not strong against an impact, and if a large impact is received at the time of contact with the bearing, the bearing sleeve 10, particularly its corners may be damaged. In particular, the contact at the time of high-speed rotation has a large impact, and there is a possibility that the possibility that the bearing sleeve 10 is broken increases.

As described above, in the conventional hydrostatic gas bearing spindle, since the bearing sleeve 10 is exposed at the front end face of the housing 5, when the bearing sleeve 10 is broken, fragments thereof scatter around. . The exposed portion a of the bearing sleeve 10 is a journal bearing end, and this journal bearing end is a place where there is a high possibility of contact when overload or large imbalance occurs. That is, the high-potential portion is exposed. When the bearing sleeve 10 is broken and its fragments are scattered, there is a possibility that the workpiece or the work object cannot be used.

Therefore, the present invention has been proposed in view of the above-mentioned problems, and an object of the present invention is that when a large impact is applied at the time of contact with a bearing, even if the bearing sleeve is broken, fragments thereof are scattered. Is to provide a hydrostatic gas bearing spindle having a structure capable of suppressing the above by simple means.

[0020]

According to a first aspect of the present invention, there is provided a main shaft, a bearing portion rotatably supporting the main shaft with respect to a fixed member, and
By injecting compressed gas into this bearing, in a hydrostatic gas bearing spindle holding the main shaft in a non-contact state, the bearing facing the main shaft is formed of a brittle material having self-lubricating properties. A closing means is provided so as not to be exposed to the outside.

According to the first aspect of the present invention, when the bearing portion made of a brittle material having self-lubricating properties is provided with a closing means so as not to be exposed to the outside, when a large impact is received at the time of contact with the bearing, Even if the bearing sleeve is broken, the fragments are not scattered.

As a specific structure, the invention of claim 2
A journal bearing for rotatably supporting the spindle with respect to a fixed member in a radial direction, and a thrust bearing for axially supporting the spindle by disposing the journal on both sides of a thrust plate connected to the spindle. And a hydrostatic gas bearing spindle comprising:

This hydrostatic gas bearing spindle also has
If a closing means is provided so that the bearing part formed of a brittle material having self-lubricating property is not exposed to the outside, if a large impact is received at the time of contact with the bearing, even if the bearing sleeve is broken, the fragments are scattered. There is no.

The brittle material includes graphite or a material containing graphite as a main component (Claim 3) and ceramic (Claim 4).

The closing means may be provided on a side on which a tool or the like is mounted (Claim 5), may be formed integrally with the fixing member by extending the fixing member (Claim 6), There is a separate cover member attached to the fixing member.

The invention described in any one of the first to seventh aspects has a turbine drive unit for blowing compressed air to a plurality of recesses provided on an outer peripheral portion of the main shaft to apply rotational power to the main shaft. That is, a hydrostatic gas bearing spindle using an air turbine as a driving means (Claim 8), or a rotor provided on the main shaft and a stator opposed to the rotor provided on the fixing member, And hydrostatic gas bearing spindle using an electric motor as drive means (Claim 9)
Applicable to

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a hydrostatic gas bearing spindle according to the present invention will be described in detail below. 5 and 6 are denoted by the same reference numerals.

FIG. 1 shows a first embodiment of a hydrostatic gas bearing spindle using an air turbine as a driving means. This spindle rotates the main shaft 1 by blowing compressed air to a plurality of concave portions 3 provided on the outer periphery of a thrust plate 2 of the main shaft 1 from a turbine nozzle 4 provided at a portion facing the concave portions 3. It is.

The main shaft 1 and the thrust plate 2 connected to the main shaft 1 are connected to the housings 5 and 6 by journal bearings 7 and thrust bearings 8 and 9 formed on the housings 5 and 6 which are fixed members. It is rotatably supported without contact.

The journal bearing 7 and the thrust bearing 8 are mounted on a substantially cylindrical housing 5 by a bearing sleeve 10 made of a brittle material having excellent self-lubricating properties.
Are fitted and fixed by appropriate means such as shrink fitting, press fitting, or adhesion. Similarly, the thrust bearing 9
A bearing plate 11 made of a brittle material having excellent self-lubricating properties is fitted to a circular lid-shaped housing 6 integrally joined to an end of the housing 5 by appropriate means such as shrink fitting, press fitting, or bonding. And is fixedly fitted. A plurality of fine journal bearing nozzles 12 and thrust bearing nozzles 1 are provided on the bearing sleeve 10 and the bearing plate 11 of the journal bearing portion 7 and the thrust bearing portions 8 and 9.
3, 14 are provided.

As the above-mentioned brittle material having excellent self-lubricating properties, graphite, a material containing graphite as a main component, ceramic, or a composite material of graphite and ceramic is suitable.

The compressed air supplied from the air supply port 15 is supplied to the circumferential grooves 19 and 20 via the air passages 16, 17 and 18, and from the journal bearing nozzle 12 of the journal bearing 7 of the bearing sleeve 10. The journal is jetted onto the bearing surface, and the main shaft 1 is radially supported by the journal bearing portion 7.

On the other hand, from the circumferential groove 19, the bearing sleeve 1
Compressed air is ejected from the thrust bearing nozzle 13 of No. 0 to the bearing surface of the thrust bearing portion 8. The compressed air supplied from the air supply port 15 is also supplied to the circumferential groove 21 from the air passage 16 and is jetted from the thrust bearing nozzle 14 of the bearing plate 11 to the bearing surface of the thrust bearing 9. Thus, the main shaft 1 is axially supported by the thrust bearing portions 8 and 9.

A fixing ring 22 is fixed to the housing 5 by an appropriate means such as shrink fitting, press fitting or bonding. Each of the recesses 3 of the thrust plate 2 is
A plurality of turbine nozzles 4 which are opened substantially tangentially along the inner periphery of the fixing ring 22 at a portion opposed to the above, penetrate and form an air turbine.

The compressed air supplied from the air supply port 23 passes through the air passages 24 and 25 and the circumferential groove 26 from the turbine nozzle 4 of the fixed ring 22 to the thrust plate 2 of the main shaft 1.
Are ejected substantially tangentially toward the concave portion 3 of FIG. The jetted compressed air applies a rotational force to the main shaft 1 to generate an exhaust port 2.
7 is discharged to the outside of the housing 5. A tool or a work is attached to an end (the right end in the figure) of the main shaft 1, and operations such as machining and inspection are performed.

In the first embodiment, as means for closing the bearing sleeve 10 so as not to be exposed, a wall 30 integrally protruding in the inner circumferential direction of the front end (right side in the figure) of the housing 5 is formed. The gap 31 between the inner diameter of the wall 30 and the main shaft 1 is set slightly larger than the bearing gap of the journal bearing 7. With such a configuration of the closing means, when a large impact is received at the time of bearing contact,
Even if the bearing sleeve 10 is broken, the wall 30 can prevent the fragments from being scattered. With a hydrostatic gas bearing spindle, 100,000 r / min. However, even if the bearing sleeve 10 is damaged due to a large impact during such high-speed rotation, the wall 30 can reliably prevent the fragments from being scattered.

In the first embodiment, the case where the wall 30 is formed integrally with the front end of the housing 5 is shown. However, the present invention is not limited to this, and the second embodiment shown in FIG. As in the embodiment, the wall (cover member) 32 may be formed separately from the housing 5, and the wall 32 may be fastened to the housing 5 with bolts 33. Further, as in the third embodiment shown in FIG. 3, a wall 32 separate from the housing 5 may be fitted to the housing 5 by a fitting surface 34. Note that the separate wall 32 in the second and third embodiments can be attached to the housing 5 by other means such as bonding.

FIG. 4 shows a fourth embodiment of a hydrostatic gas bearing spindle using an electric motor as a driving means. Since the basic configuration of this hydrostatic gas bearing spindle is the same as that of the spindle of FIG. 1, the same parts are denoted by the same reference numerals.

The main shaft 1 and the thrust plate 2 connected to the main shaft 1 are rotated in a non-contact manner with respect to the housings 5 and 6 by journal bearings 7 and thrust bearings 8 and 9 formed on the housings 5 and 6. It is freely supported. The materials of the main shaft 1 and the housings 5 and 6 are the same as those in the first embodiment.

The journal bearing 7 and the thrust bearing 8 are mounted on a substantially cylindrical housing 5 by a bearing sleeve 10 formed of a brittle material having excellent self-lubricating properties.
Are fitted and fixed by appropriate means such as shrink fitting, press fitting, or adhesion. Similarly, the thrust bearing 9
A bearing plate 11 made of a brittle material having excellent self-lubricating properties is fitted to a circular lid-shaped housing 6 integrally joined to an end of the housing 5 by appropriate means such as shrink fitting, press fitting, or bonding. And is fixedly fitted. A plurality of fine journal bearing nozzles 12 and thrust bearing nozzles 1 are provided on the bearing sleeve 10 and the bearing plate 11 of the journal bearing portion 7 and the thrust bearing portions 8 and 9.
3, 14 are provided. The brittle material having excellent self-lubricating properties described above may be the same as in the first embodiment.

The compressed air supplied from the air supply port 15 is supplied to the circumferential grooves 19 and 20 via the air passages 16, 17 and 18, and from the journal bearing nozzle 12 of the journal bearing portion 7 of the bearing sleeve 10. The journal is jetted onto the bearing surface, and the main shaft 1 is radially supported by the journal bearing portion 7.

On the other hand, from the circumferential groove 19, the bearing sleeve 1
Compressed air is ejected from the thrust bearing nozzle 13 of No. 0 to the bearing surface of the thrust bearing portion 8. The compressed air supplied from the air supply port 15 is also supplied to the circumferential groove 21 from the air passage 16 and is jetted from the thrust bearing nozzle 14 of the bearing plate 11 to the bearing surface of the thrust bearing 9. Thus, the main shaft 1 is axially supported by the thrust bearing portions 8 and 9.

A stator (stator) 28 is disposed near the center of the housing 5, and a motor is constituted by a rotor (rotor) 29 formed at a position corresponding to the main shaft 1. In this electric motor, a rotating force is applied to the main shaft 1 on which the rotor 29 is formed by energizing the stator 28. A tool or a work is attached to an end (the right end in the figure) of the main shaft 1, and operations such as machining and inspection are performed.

As the closing means in the fourth embodiment, similarly to the first embodiment, a wall 30 is integrally formed at the front end (right side in the figure) of the housing 5 and protrudes in the inner circumferential direction. A gap 31 between the inner diameter of the wall 30 and the main shaft 1
Is set slightly wider than the bearing clearance of the journal bearing 7. With such a configuration of the closing means, even when the bearing sleeve 10 is damaged when the bearing is subjected to a large impact at the time of contact with the bearing, the fragments can be prevented from being scattered by the wall 30.

In the fourth embodiment, similarly to the second and third embodiments, the wall (cover member) 32 is separate from the housing 5, and the wall 32 is bolted to the housing 5. 33, or
A wall 32 separate from the housing 5 is attached to the housing 5 by the fitting surface 3.
4, and the separate wall 32 can be attached to the housing 5 by other means such as bonding.

In the first to fourth embodiments, the case where the self-contained throttle type hydrostatic gas bearing is applied is shown. However, other bearing types such as a porous restrictor may be made of graphite having excellent self-lubricating properties. If used, seizure resistance at the time of contact with the bearing can be improved, and by providing the closing means of the present invention as in the above-described embodiment, scattering of fragments when the bearing sleeve is lost can be prevented.

[0047]

According to the present invention, the main shaft, the bearing for rotatably supporting the main shaft with respect to the fixed member, and the compressed gas being ejected from the bearing to maintain the main shaft in a non-contact state. In the hydrostatic gas bearing spindle described above, the bearing portion facing the main shaft is formed of a brittle material having self-lubricating properties, and a closing means is provided so that this bearing portion is not exposed to the outside, so that a large impact occurs at the time of bearing contact. In the case where the bearing sleeve is damaged, even if the bearing sleeve is broken, the closing means can prevent the fragments from being scattered, so that the workpiece or the work object is not damaged, and the safe static pressure is provided. A gas bearing spindle can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a hydrostatic gas bearing spindle according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a partial cross-sectional view illustrating a third embodiment of the present invention.

FIG. 4 is a sectional view showing a fourth embodiment of the present invention.

FIG. 5 is a sectional view showing a conventional example of a hydrostatic gas bearing spindle.

FIG. 6 is a cross-sectional view showing another conventional example of a hydrostatic gas bearing spindle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main shaft 2 Thrust plate 5, 6 Fixing member (housing) 7 (Journal) bearing part 8, 9 (Thrust) bearing part 10 Bearing sleeve 11 Bearing plate 12 Journal bearing nozzle 13, 14 Thrust bearing nozzle 28 Stator 29 Rotor 30 Closing means (wall) 32 Closing means (cover member)

Claims (9)

[Claims] A spindle, a bearing for rotatably supporting the spindle with respect to a fixed member, and a hydrostatic gas bearing spindle for holding the spindle in a non-contact state by injecting compressed gas into the bearing. 2. The hydrostatic gas bearing spindle according to claim 1, wherein a bearing portion facing the main shaft is formed of a brittle material having self-lubricating properties, and a closing means is provided so that the bearing portion is not exposed to the outside. 2. The hydrostatic gas bearing spindle has a main shaft, a journal bearing portion rotatably supporting the main shaft with respect to a fixed member, and opposed to both sides of a thrust plate connected to the main shaft. 2. The hydrostatic gas bearing spindle according to claim 1, further comprising a thrust bearing portion for axially supporting the main shaft. 3. The hydrostatic gas bearing spindle according to claim 1, wherein the brittle material is graphite or a material containing graphite as a main component. 4. The hydrostatic gas bearing spindle according to claim 1, wherein the brittle material is ceramic. 5. The hydrostatic gas bearing spindle according to claim 1, wherein said closing means is provided on a side on which a tool or the like is mounted. 6. The hydrostatic gas bearing spindle according to claim 1, wherein said closing means is integrally formed by extending said fixing member. 7. The apparatus according to claim 1, wherein the closing means is a separate cover member attached to the fixing member.
7. The hydrostatic gas bearing spindle according to any one of claims 6 to 6. 8. The static pressure gas according to claim 1, further comprising an air turbine that blows compressed air to a plurality of recesses provided on an outer peripheral portion of the main shaft to apply rotational power to the main shaft. Bearing spindle. 9. The hydrostatic gas bearing spindle according to claim 1, wherein a rotor of an electric motor is provided on the main shaft, and a stator of the electric motor facing the rotor is provided on the fixing member. .