JP2002039182A - Noncontact bearing spindle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noncontact bearing spindle device of good productivity, being compatible with a new bearing sleeve and easy to repair if damaged. SOLUTION: A main spindle 4 is supported by a static pressure/magnetic compound bearing or a single static pressure gas bearing 2. The static pressure gas bearing 2 has a bearing sleeve 11 fitted over the inside diameter surface of a housing 5 to form a bearing clearance d1 between the sleeve and the main spindle 4. The inside diameter surface of the bearing sleeve 11 is dimensioned and configured to form the predetermined bearing clearance d1 when the bearing sleeve 11 is fitted into the housing 5. In this case, a shrinkage fit between the bearing sleeve 11 and the housing 5 is not greater than half the desired bearing clearance. The housing 5 is made from a material having a greater coefficient of thermal expansion and a greater heat conductivity and a smaller modulus of longitudinal elasticity than the material from which the bearing sleeve 11 is made.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact bearing spindle device provided with a hydrostatic gas bearing or a hydrostatic magnetic composite bearing.

[0002]

2. Description of the Related Art In a static pressure gas spindle device or a static pressure magnetic compound spindle device, the management of bearing clearance is very important.
The stator and the rotor are merged. In other words, on the stator side, after the bearing sleeve is shrink-fitted into the housing, the bearing surface is finished by grinding, and then the outer diameter of the main shaft as the rotor is ground so that the bearing clearance becomes a specified value. I do.

[0003]

As a result, productivity is poor, and it is difficult to unitize at the component level, and there is no compatibility. In addition, if the bearing part is damaged due to touch-down for any reason, the bearing surface is polished again and the main shaft is plated, sprayed, etc. as much as the inner diameter is increased, and the bearing gap remains the same as before. So that the outer diameter is ground. Thus, there are many steps for repair.

An object of the present invention is to provide a non-contact bearing spindle device which has good productivity, is compatible with a new bearing sleeve, and is easy to repair in case of damage. Another object of the present invention is to facilitate mounting of the bearing sleeve to the housing and to ensure accuracy of the inner diameter and the inner diameter shape of the fitted bearing sleeve. Still another object of the present invention is to reduce the influence of a bearing gap due to a temperature rise due to a bearing loss or the like during operation.

[0005]

A non-contact bearing spindle device according to the present invention comprises a non-contact bearing composed of a hydrostatic gas bearing or a hydrostatic magnetic composite bearing in which a hydrostatic gas bearing and a magnetic bearing are combined to form a main shaft. In the non-contact bearing, the bearing sleeve is fitted on the inner diameter surface of the housing, and a bearing gap of the hydrostatic gas bearing is formed between the bearing sleeve and the main shaft. In this non-contact bearing spindle device, the relationship between the housing and the bearing sleeve is set such that the bearing sleeve is fitted into the housing so that the inner diameter surface of the bearing sleeve has a size and shape that forms a predetermined bearing gap. It was done. According to this configuration, by fitting the bearing sleeve into the housing, the bearing sleeve is compressed and deformed, and the inner diameter surface of the bearing sleeve forms a predetermined bearing gap. Therefore, it is not necessary to combine the bearings, accuracy can be ensured by fitting, and assembly of the bearing is facilitated. In addition, when the bearing sleeve is damaged by touchdown or the like, it can be recovered by replacing the bearing sleeve with a new bearing sleeve, and the processing on the spindle side is not required. Therefore, repair in case of damage is easy. The dimension and shape for forming the predetermined bearing gap are dimensions and shape such that the inner diameter surface of the bearing sleeve falls within a target tolerance range.

In the present invention, the bearing sleeve is preferably shrink-fitted to the housing, and the shrink-fitting margin is preferably set to be not more than 1/2 of a target bearing clearance. As described above, by setting the shrink fit to 1/2 or less of the target bearing clearance,
Accuracy of the bearing gap after shrink fitting can be easily secured.

In the present invention, it is preferable that the material of the housing has a larger coefficient of thermal expansion and thermal conductivity and a smaller coefficient of longitudinal elasticity than the material of the bearing sleeve. As described above, the housing is made of a material having a larger thermal expansion coefficient and a higher thermal conductivity than the bearing sleeve, so that the shrink-fitting process becomes very easy, and the bearing sleeve after assembly can be removed. Also,
When the longitudinal elastic modulus of the bearing sleeve is larger than that of the housing, by appropriately designing the radial thickness of both,
The change in the inner diameter of the bearing sleeve due to shrink fitting is extremely small, and the shape accuracy is not impaired. Therefore,
The outer diameter of the main shaft can be sufficiently ensured without finishing at the present time after shrink fitting of the bearing sleeve.

[0008] In the present invention, it is preferable to provide a cooling means for cooling the housing. During the operation of the spindle, the temperature of the bearing sleeve increases due to bearing loss, and the shrinkage allowance with the housing decreases. Therefore, by cooling the outer diameter of the housing by the cooling means, it is possible to prevent a reduction in shrinkage allowance due to such a rise in temperature during operation.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. This non-contact bearing spindle device 1 has a main shaft 4 supported by a radial type static pressure gas bearing 2 and an axial type static pressure gas bearing 3 which are non-contact bearings, and a spindle drive source 10 is provided. Spindle drive source 10
Is a built-in type motor, which includes a rotor 21 provided on the main shaft 4 and a stator 22 provided on the housing 5.

In the radial type hydrostatic gas bearing 2, a bearing sleeve 11 is fitted on the inner diameter surface of the housing 5 of the spindle device 1, and a bearing gap d 1 is formed between the bearing sleeve 11 and the main shaft 4. The bearing sleeve 11 has a bearing clearance d1.
An air supply hole 14 serving as a throttle is provided. The air supply holes 14 are provided at a plurality of locations aligned in the circumferential direction of the bearing sleeve 11 and are provided at a plurality of locations apart in the axial direction. The axial type hydrostatic gas bearing 3 has a pair of bearing rings 12 and 13 facing both sides of a flange 4 a provided on the main shaft 4, and a hydrostatic gas bearing is provided between the bearing rings 12 and 13 and the flange 4 a. No. 3 bearing gap d2 is formed. The bearing rings 12 and 13 are fitted on the inner diameter surface of the housing 5. Each of the bearing rings 12 and 13 is provided with an air supply hole 15 serving as a throttle opening into the bearing gap d2. The air supply holes 15 are provided at a plurality of locations arranged in the circumferential direction.

The bearing ring 12 at the tip of the spindle in the axial type static pressure gas bearing 3 also serves as a static pressure gas bearing 18 for protection during touchdown, and is provided in a radial bearing gap between the bearing 4 and the main shaft 4. 20. A static pressure gas bearing 19 for touchdown protection is also provided at a position aligned with the rear end side of the main shaft of the radial type static pressure gas bearing 2, and an air supply hole 21 opening in a radial bearing gap between the main shaft 4 and the main shaft 4. have.

The air supply holes 14, 15, 20, 21 in each of the static pressure gas bearings 2, 3, 18, 19 are provided in the housing 5.
It communicates with an air supply inlet 17 that opens to the outside of the housing 5 through an air supply passage 16 provided therein. Air supply inlet 1
7 is a supply source of a pressurized gas such as a compressor (not shown)
Is connected to the pipe. In addition, bearing gaps d1, d2 in each of the radial type and the axial type hydrostatic gas bearings 2, 3
On the other hand, a discharge path 39 for releasing the static pressure gas out of the apparatus is provided in the bearing sleeve 11, the housing 5, and the like.

An outer peripheral portion of the housing 5 has an axial position corresponding to the hydrostatic gas bearing 2 and a spindle drive source 10.
Cooling means 23 and 24 are provided at axial positions corresponding to the above. These cooling means 23 and 24 are composed of a cooling medium flow path composed of a jacket or the like, and are connected to cooling units (not shown) from the cooling medium entrances and exits 25 and 26.

The housing 5 is divided into a plurality of members. That is, the housing 5 includes a housing body 5A fitted on the outer periphery of the bearing sleeve 11, a cooling jacket 5B fitted on the outer periphery of the housing body 5A, and other housing components 5C to 5G. . A cooling medium flow path of the cooling means 23 is formed between the housing body 5A and the cooling jacket 5B.
The flange 5a at the front end of the housing 5 is constituted by a housing component 5c.

The bearing sleeve 11 and the housing 5 have the following relationship. Before the bearing sleeve 11 is incorporated into the housing 5, the inner and outer diameters of the bearing sleeve 11 are finished and prepared as a finished part. In other words, the bearing sleeve 11 is completed as a unit. Bearing sleeve 1
The shrinkage allowance (in the radial direction) between the housing 1 and the housing 5 is １ ／ or less of the target value of the bearing gap d1. The material of the housing 5 has a larger coefficient of thermal expansion and thermal conductivity and a smaller coefficient of longitudinal elasticity than the bearing sleeve 11. As an example having such a material relationship, for example, a housing 5
Can be duralumin, and the bearing sleeve 11 can be stainless steel. In the case where the housing 5 has a divided structure as in this embodiment and the like, the materials of the members constituting the housing 5 may be different, but at least a member constituting a portion fitted to the outer periphery of the bearing sleeve 11. (In this embodiment, the housing main body 5A) has a material and dimension relationship with the bearing sleeve 11 described above.

According to the non-contact bearing spindle device having the above structure, the material of the housing 5 is made to have a larger thermal expansion coefficient and thermal conductivity than that of the bearing sleeve 11, and the shrink fit is set to 1 / the target value of the bearing clearance d1. Since it is 2 or less, the step of shrink-fitting the bearing sleeve 11 to the housing 5 becomes very easy, and the bearing sleeve 11 after assembly can be removed. Further, since the longitudinal elastic coefficient of the bearing sleeve 11 is larger than that of the housing 5, by designing the thickness in the radial direction of the two members in an appropriate relationship, the inner diameter change of the bearing sleeve 11 due to shrink fitting becomes extremely small, and the shape accuracy is also improved. There is no loss. Therefore, the outer diameter of the main shaft 4 does not have to be finished at present after shrink fitting of the bearing sleeve 11. During spindle operation, the temperature of the bearing sleeve 11 rises due to bearing loss, and the shrinkage allowance with the housing 5 decreases as it is. However, the provision of the cooling means 23 prevents the shrinkage allowance during operation from decreasing. You.

When the bearing gap d1 is small (for example, about several μm), it is difficult to omit the conventional process as in the prior art. However, like the spindle device for high-speed rotation,
In the case of a relatively large bearing gap (for example, 15 μm or more), the rate of change of the bearing gap due to processing errors is small. Therefore, the bearing sleeve 11 can be made compatible as described above, and accuracy can be ensured without performing the integration.

FIG. 2 shows another embodiment of the present invention.
In the non-contact bearing spindle device 1A, the main shaft 4 is supported by radial-type hydrostatic composite bearings 6, 7 and axial-type hydrostatic composite bearings 8, 9, which are non-contact bearings, and a spindle drive source 10 is provided. It is a thing. Each of the hydrostatic and magnetic composite bearings 6 to 9 is a composite of a hydrostatic gas bearing 6A to 9A and a magnetic bearing 6B to 9B, respectively. The term “combination of bearings” as used herein means that both types of hydrostatic and magnetic bearings are combined so as to produce a common part. For example, even if some parts are shared by both types of bearings Good. In this example, the cores of the magnetic bearings 6B to 9B constitute part of the bearing surfaces of the hydrostatic gas bearings 6A to 9A.

The radial type hydrostatic gas bearings 6, 7 are formed on a bearing sleeve 11A, and the bearing sleeve 11A is fitted on the inner diameter surface of the housing 5A. The bearing sleeve 11A forms a part of the core of the magnetic bearings 6B and 7B. The relationship between the housing 5A and the bearing sleeve 11A is set to the same relationship as in the above embodiment. That is, before the bearing sleeve 11A is assembled into the housing 5A, the inner and outer diameters of the bearing sleeve 11A are finished and prepared as a finished part. Bearing sleeve 11A and housing 5
The shrink-fitting margin (in the radial direction) with A is set to １ ／ or less of the target value of the bearing gap d1. The material of the housing 5A has a larger coefficient of thermal expansion and thermal conductivity and a smaller coefficient of longitudinal elasticity than the bearing sleeve 11A. In this embodiment, portions corresponding to those in the embodiment of FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

As described above, when the non-contact bearings are the hydrostatic magnetic composite bearings 6 and 7, similarly to the above, the bearing sleeve 1 is provided.
1A as a compatible product, housing 5A and bearing sleeve 11
A with A can be omitted.

FIGS. 3 and 4 show examples of a support structure in which a non-contact bearing spindle device is installed on a support base. In each example, the spindle device 1 of the embodiment of FIG. 1 is used. Instead of the one in FIG. 1, the one in FIG. 2 may be used. As shown in FIGS. 3 and 4, the support structure of the non-contact bearing spindle device fixes the housing 5 of the spindle device 1 to the support base 40 with a flange 5 a at the front end of the housing 5. 5 is fixed by fixing means 41 and 41A. The support 40 has a box-like or cylindrical shape into which the non-contact bearing spindle device 1 fits. The flange 5 a at the front end of the housing 5 is fixed to the support 40 with bolts 42.

In the example shown in FIG. 3, the fixing means 41 for fixing the rear portion of the housing 5 is rigidly supported on the support base 40, and a bolt is used. In the example of FIG. 4, the fixing means 41A for fixing the rear part of the housing 5 is made of an elastic body which elastically supports, and for example, an O-ring is used.

The operation of the support structure will be described. When the support synthesis of the housing 5 is insufficient, the non-contact spindle device 1 limits the maximum number of revolutions due to the natural frequency, and when applied to machining, generates chatter vibration and may adversely affect the machined surface. . In particular, in a hydrostatic gas bearing or a hydrostatic magnetic composite bearing spindle device, the axial length of the radial bearing portion is long due to its structure, and the motor portion is often placed at the rearmost portion of the main shaft. In this case, it is not possible to secure a sufficient support composition by fixing only the flange portion 5a provided in the above. On the other hand, by providing the fixing means 41 and 41A for supporting the rear portion of the housing 1 as in each of the above examples, it is possible to obtain support rigidity and prevent chatter vibration and the like.

[0024]

According to the non-contact bearing spindle device of the present invention, the main shaft is supported by a non-contact bearing comprising a hydrostatic gas bearing or a hydrostatic magnetic composite bearing in which a hydrostatic gas bearing and a magnetic bearing are combined. The non-contact bearing is a non-contact bearing spindle device in which a bearing sleeve is fitted to an inner diameter surface of a housing and a bearing gap of a hydrostatic gas bearing is formed between the bearing sleeve and the main shaft. , The relationship between the housing and the bearing sleeve is set so that the inner diameter surface of the bearing sleeve has a size and shape that forms a predetermined bearing gap. Compatibility with new ones and easy repair in case of damage.
When the shrink fit of the bearing sleeve with the housing is set to 1/2 or less of the target bearing clearance, it is easy to secure the accuracy of the inner diameter of the bearing sleeve after shrink fitting. If the housing is made of a material having a larger coefficient of thermal expansion and thermal conductivity and a smaller coefficient of longitudinal elasticity than the bearing sleeve, the bearing sleeve can be easily attached to the housing, and the bearing sleeve after fitting is formed. The accuracy of the inner diameter size and inner diameter shape can be secured. When the cooling means for cooling the housing is provided, the influence of a bearing gap caused by a temperature rise due to a bearing loss or the like during operation is reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a non-contact bearing spindle device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a non-contact bearing spindle device according to another embodiment of the present invention.

3 is a sectional view of an example of a support structure in which the non-contact bearing spindle device according to the embodiment of FIG. 1 is installed on a support base.

FIG. 4 is a cross-sectional view of another example of a support structure in which the non-contact bearing spindle device according to the embodiment of FIG. 1 is installed on a support base.

[Explanation of symbols]

 1, 1A: Non-contact bearing spindle device 2: Hydrostatic gas bearing 4: Main shaft 5: Housing 6, 7: Static magnetic composite bearing 6A, 7A: Static pressure gas bearing 6B, 7B: Magnetic bearing 10: Spindle drive source 11 ... bearing sleeve 23 ... cooling means d1 ... bearing gap

Claims (4)

[Claims] The main shaft is supported by a non-contact bearing comprising a hydrostatic gas bearing or a hydrostatic magnetic composite bearing in which a hydrostatic gas bearing and a magnetic bearing are combined, and the non-contact bearing is provided on an inner surface of a housing. In a non-contact bearing spindle device in which a bearing sleeve is fitted and forms a bearing gap of a hydrostatic gas bearing between the bearing sleeve and the main shaft, the inner diameter of the bearing sleeve is obtained by fitting the bearing sleeve into the housing. A non-contact bearing spindle device, wherein the relationship between the housing and the bearing sleeve is set such that the surface has a size and a shape forming a predetermined bearing clearance. 2. The non-contact bearing spindle device according to claim 1, wherein the bearing sleeve is shrink-fitted to the housing, and a shrink-fit margin is set to be not more than １ ／ of a target bearing clearance. 3. The material of the housing has a larger coefficient of thermal expansion and thermal conductivity than the material of the bearing sleeve.
3. The method according to claim 1, wherein the longitudinal elastic modulus is small.
A non-contact bearing spindle device according to claim 1. 4. The non-contact bearing spindle device according to claim 1, further comprising cooling means for cooling the housing.