JP2002005163A - Noncontact bearing spindle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a spindle in touch down, and to prevent contact of the spindle with a sliding member for protecting the spindle by thermal expansion. SOLUTION: Radial type static pressure magnetic composite bearings 6 and 7 support the spindle 4. A housing 5 is provided with the sliding member 41 closing to the spindle 4 via a radial clearance. The radial clearance d3 of the sliding member 41 is set lower than a bearing clearance d of bearing surfaces 6A and 7A forming the magnetic composite bearings 6 and 7. The sliding member 41 is provided with an air supply hole 51 for supplying cooling air between the sliding member 51 and the spindle 4.

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 such as a hydrostatic magnetic composite bearing spindle device provided in a high-speed cutting device or a grinding device.

[0002]

2. Description of the Related Art In order to perform highly efficient and highly accurate machining,
High-speed rotation is possible, with high rotation accuracy,
A spindle device with high dynamic rigidity is required. In response to this demand, the present applicant has proposed a hybrid type non-contact bearing in which a hydrostatic gas bearing and a magnetic bearing are combined (Japanese Patent Application No. Hei 10 (1994) -197686).
0-097505). According to this, it is possible to provide a compact bearing that utilizes the characteristics of both bearings, that is, excellent dynamic rigidity and rotational accuracy of the hydrostatic gas bearing, and excellent static rigidity of the magnetic bearing.

[0003]

The static pressure magnetic composite bearing is a non-contact bearing. However, when an excessive load is applied,
The main shaft may contact the bearing surface. For such contact of the main shaft, so-called touchdown, a conventional magnetic bearing spindle uses a protection bearing composed of a rolling bearing. However, since the hydrostatic magnetic composite bearing is formed by forming a hydrostatic gas bearing on the magnetic bearing portion, the gap between the main shaft of the bearing portion and the magnetic bearing stator is narrow, for example, tens of microns or less. Protective bearings consisting of commonly used rolling bearings cannot be used. Further, since the static pressure gas bearing surface forms the electromagnet of the magnetic bearing, the material of the static pressure gas bearing surface is limited to a magnetic metal having no lubrication. Therefore, when an excessive load is applied to the spindle, contact between the main shaft and the bearing surface may adversely affect the bearing portion.

For the purpose of protection during such touchdown, the present applicant has proposed to provide a sliding member in a hydrostatic magnetic composite bearing spindle device (Japanese Patent Application No. 11-7150).
No. 2). However, when the main shaft rotates at a high speed through a minute gap (below the bearing clearance) between the sliding material and the main shaft, the main shaft may expand due to air frictional heat in the bearing and may come into contact with the sliding material. . Such a problem occurs not only in the case of using a hydrostatic magnetic composite bearing but also in a spindle device generally using a non-contact bearing that supports a main shaft through a minute gap, such as a hydrostatic gas bearing. Further, the above-mentioned proposal example is a measure for the radial bearing, and does not consider protection of the thrust bearing portion.

An object of the present invention is to use a non-contact bearing having a small bearing clearance to prevent an influence on the bearing and the spindle during touchdown of the spindle, and to provide a sliding member for preventing the influence by thermal expansion of the spindle. An object of the present invention is to provide a non-contact bearing spindle device capable of preventing contact. Another object of the present invention is to improve wear resistance and sliding characteristics at the time of touchdown in a thrust type non-contact bearing.

[0006]

A non-contact bearing spindle device according to the present invention is a spindle device in which a main shaft is supported by a radial type non-contact bearing. Cooling gas supply means provided in a housing provided with a contact bearing, wherein a radial gap of the sliding member is set to be smaller than a radial bearing gap of the non-contact bearing, and a cooling gas is supplied to the radial gap of the sliding member. Is provided. According to this configuration,
When an excessive load is applied to the spindle and touchdown occurs, that is, when there is mechanical contact between the spindle and the stationary member,
The mechanical contact is limited to the contact between the sliding member and the main shaft. As the sliding material, a material having a small coefficient of friction such as carbon or graphite can be used. Therefore, the spindle device does not damage the spindle, the bearing surface, or the sliding material even by touchdown. Although the gap between the sliding material and the main shaft is a minute gap, the cooling gas supply means for supplying cooling gas to the radial gap between the sliding material and the main shaft is provided, so that the thermal expansion of the main shaft due to air frictional heat in the minute gap Can be suppressed. Therefore, it is possible to prevent the main shaft from thermally expanding and coming into contact with the sliding member.

[0007] The cooling gas supply means may have an air supply hole opened on the inner peripheral surface of the sliding member, and a cooling gas supply path for supplying a cooling gas to the air supply hole. By providing the air supply hole opened in the inner peripheral surface of the sliding member in this manner, it is possible to efficiently supply the cooling gas to the minute gap between the sliding member and the main shaft with a simple configuration. When the air supply hole is provided in this manner, the inner peripheral surface of the sliding member may be a static pressure gas bearing surface that supports the main shaft with a static pressure of gas discharged from the air supply hole. If the inner peripheral surface of the sliding member is a hydrostatic gas bearing surface, an automatic centering action by static pressure can be obtained even if the sliding member and the main shaft are not accurately aligned. Therefore, when the sliding member is replaced, the minute gap between the main shaft and the small eccentricity due to the mounting error does not become too small locally, and the sliding member can be replaced in practice.

In the present invention, the non-contact bearing is a radial-type hydrostatic composite bearing in which a hydrostatic gas bearing and a magnetic bearing are combined, and the radial clearance of the sliding member is
The bearing may be set to be equal to or less than the radial bearing gap between the static pressure gas bearing and the magnetic bearing constituting the above-described static pressure magnetic composite bearing. The hydrostatic magnetic composite bearing can be a compact bearing that takes advantage of the characteristics of both bearings: the excellent dynamic rigidity and rotational accuracy of a hydrostatic gas bearing, and the excellent static rigidity of a magnetic bearing.
On the other hand, the gap between the bearing surface of the hydrostatic gas bearing and the main shaft becomes minute. For this reason, the gap between the sliding member and the main shaft becomes smaller than that, and the problem of contact due to the thermal expansion of the main shaft due to the above-mentioned air frictional heat is likely to occur. This can prevent contact due to expansion of the main shaft. Even when the non-contact bearing is a hydrostatic gas bearing, it is necessary to make the gap between the sliding member and the main shaft very small as in the case of the hydrostatic magnetic composite bearing. However, cooling gas supply means is provided to cool the main shaft. This can prevent contact due to expansion of the main shaft.

[0009] The non-contact bearing spindle device of the present invention comprises:
A thrust type non-contact bearing for supporting the main shaft in a non-contact manner facing the flange formed on the main shaft is provided, and either a bearing surface of the thrust type non-contact bearing or a flange surface of the main shaft facing the bearing surface is provided. A sprayed layer of molybdenum or carbon may be provided on one of the surfaces, and a sprayed layer of ceramic may be provided on the other surface of the bearing surface and the flange surface of the main shaft. When the thrust type non-contact bearing is provided, the support of the spindle during operation can be performed completely non-contact with the use of the radial type non-contact bearing. In this case, by providing the sprayed layer of the above-described material on the bearing surface and the spindle flange surface as described above, it is possible to improve wear resistance and sliding characteristics at the time of touchdown in the thrust direction. As for the thrust bearing, it is difficult to place sliding members in parallel in the same manner as the radial bearing. In order to place the sliding material without reducing the original bearing area, the diameter of the flange of the main shaft must be increased, but the natural frequency will be significantly reduced. However, by providing the sprayed layer on the bearing surface as described above, it is possible to provide protection during touchdown without increasing the flange diameter.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. The non-contact bearing spindle device 1 includes a main shaft 4 and a plurality of radial type non-contact bearings, which are static pressure magnetic composite bearings 6 and 7 installed in a housing 5.
Hydrostatic magnetic composite bearings 8, 9 as thrust type non-contact bearings
And a hydrostatic magnetic composite bearing spindle device provided with a spindle drive source 10. Spindle drive source 10
Is a motor built in the housing 5 and includes a rotor 21 provided integrally with the main shaft 4 and a stator 22 provided in the housing 5, and constitutes a spindle device 1 of a built-in motor type. A chuck 12 for attaching a tool 11 is provided at the tip of the main shaft 4. The arrangement of each of the bearings 6 to 9 and the spindle drive source 10 is, in this example,
The front part (tool side part) and the rear part of the main shaft 4 are supported by radial type hydrostatic composite bearings 6 and 7, the middle of which is supported by thrust type hydrostatic composite bearings 8 and 9, and a spindle is provided at the rear end. The configuration is such that the drive source 10 is arranged.

In the spindle device 1 having this configuration, the sliding member 4 whose inner diameter surface is close to the main shaft 4 through the radial gap.
1 is installed in the housing 5. The sliding member 41 is arranged on the front end side and the rear end side of the main shaft 4 with respect to the arrangement of the radial type hydrostatic magnetic composite bearings 6 and 7, respectively. Each sliding material 41
Is a ring-shaped member, which is fitted to a sliding member fitting portion provided on the housing 5 in a fitted state. The inner surface 41a of the sliding member 41 is formed in a cylindrical shape.
a and a radial gap d3 between the outer diameter surface of the main shaft 4 (FIG. 3)
Is set to be equal to or less than the radial bearing gap d (FIG. 3) between the static pressure gas bearings 6A, 7A and the magnetic bearings 6B, 7B constituting the radial type static pressure magnetic composite bearings 6, 7. The material of the sliding material 41 is carbon or graphite, the hardness of which is 50 or more in shear hardness, the bending strength is 400 kgf / cm ² or more,
Compressive strength is 700 kgf / cm ² or more and thermal expansion coefficient is 5
× 10 ^-6 or less.

The sliding member 41 is provided with cooling gas supply means 50 for supplying a cooling gas to the radial gap d3. In FIG. 3, the cooling gas supply means 50 is
1 has an air supply hole 51 opened on the inner peripheral surface thereof and a cooling gas supply path 52 for supplying a cooling gas to the air supply hole 51, and is connected to a cooling gas supply source 53. The inner peripheral surface 41 a of the sliding member 41 is a static pressure gas bearing surface that supports the main shaft 4 by static pressure due to gas discharged from the air supply hole 51. The air supply holes 51 are provided at a plurality of positions in the circumferential direction of the sliding member 41. Each of these air supply holes 51 is provided with one cooling gas supply passage 52.
From the branch. The cooling gas supply source 53 supplies a cooling gas such as air, and a pump or a blower is used. The cooling gas supply source 53 is provided separately from the gas supply source for the static pressure bearing, even if the cooling gas supply source 53 also serves as the gas supply source for the static pressure bearing that supplies the working gas to the static pressure magnetic composite bearings 6 and 7. It may be.

The configuration of each of the hydrostatic magnetic composite bearings 6 to 9 in FIG. 1 will be described. Each of the radial type hydrostatic magnetic composite bearings 6, 7
FIG. 2 shows a cross section of one of the bearings 6, and FIG. 3 shows an enlarged vertical section of one of the bearings. The hydrostatic magnetic composite bearings 6 and 7 are each a hydrostatic gas bearing 6
A, 7A and magnetic bearings 6B, 7B are combined. The term "combination" as used in this specification means that both types of bearings of a static pressure type and a magnetic type are combined so as to generate a common part. For example, a common part (a radial bearing) In this case, an axially overlapping portion may be generated, or at least a part of parts may be shared by both types of bearings.

In this embodiment, as shown in FIG. 3, the throttle 23a of the hydrostatic gas bearings 6A, 7A is provided on the core 23 of the electromagnet of the magnetic bearings 6B, 7B, so that the hydrostatic gas bearing surface is formed on the core 23. Is part of. The core 23 includes a pair of main core portions 23a, 23a separated in the axial direction, a connection core portion 23b connecting the main core portions 23a, 23a,
Extending portions 23c, 23c extending from the main shaft side ends of both main core portions 23a, 23a to face each other have a C-shaped vertical section. The inner diameter side surfaces of the main core portion 23a and the extension portion 23c are cylindrical surfaces forming a predetermined magnetic gap with the main shaft 4. The magnetic bearings 6B and 7B are formed by winding a coil 25 around a connecting core portion 23b of the core 23. The coil 25 is embedded in a non-magnetic body 26 such as a resin material.

The static pressure gas bearings 6A, 7A are formed on the inner diameter side surface of the core 23 and the non-magnetic body 26 and form a bearing gap d between the main shaft 4 and the static pressure magnetic bearing surfaces 6Aa, 7Aa.
The diaphragm 23 is provided on each of the main core portions 23a, 23a of the core 23 and opens on the hydrostatic bearing surfaces 6Aa, 7Aa. The throttles 24a are provided at the ends of the air supply holes 24 opened on the outer diameter side surfaces of the main core portions 23a. As shown in a stepped cross section in FIG. 2, the cores 23 are arranged at a plurality of circumferential positions around the main shaft 4 (four in the example of FIG. 2) and fixed to the housing 5. The gap between the circumferentially adjacent cores 23 is filled with a non-magnetic material 27 such as a resin material.
The non-magnetic body 27 is formed around the non-magnetic body 26 around the coil 25.
(FIG. 4). The non-magnetic members 26 and 27 and the core 23 form the static pressure magnetic bearing surface 6A.
a and 7Aa.

The magnetic bearings 6B and 7B are composed of a main shaft 4 and a core 23.
And a displacement detecting means 28 for detecting the displacement of the magnetic gap between them. The displacement detecting means 28 may directly detect the displacement amount, but in this example, the static pressure (gas pressure) of the static pressure bearing gap d is detected, and the pressure detection value is detected. The displacement of the magnetic gap is detected by converting the displacement into a displacement amount. Specifically, the displacement detecting means 28
Is a pressure detection air passage 28a having an open end at the static pressure bearing gap d, and a sensor 28b communicating with the air passage 28a.
It is composed of The sensor 28b is, as shown in FIG.
3 is disposed at a position axially distant from 3. Ventilation path 2
Numeral 8a is formed by a fine hole or a pipe, and is opened in the hydrostatic bearing gap d at the portion of the nonmagnetic body 26 between the extending portions 23c of the core 23. In FIG. 2, the opening positions of the throttle 24 a and the air passage 28 a are shifted in the circumferential direction for easy viewing of the drawing, but they are actually at the same position in the circumferential direction.

FIG. 4 is an enlarged view of the thrust-type hydrostatic magnetic bearings 8 and 9. The pair of bearings 8, 9 are opposed to both surfaces of a flange 4 a provided on the
And constitute one double-sided thrust-type hydrostatic gas bearing 30. The hydrostatic composite bearings 8 and 9 on both sides have the same configuration. These static pressure magnetic composite bearings 8 and 9 are respectively composed of static pressure gas bearings 8A and 9A.
And the magnetic bearings 8B and 9B. In this embodiment, the core 3 of the electromagnet of the magnetic bearings 8B and 9B is used.
By providing throttles 34a for the static pressure gas bearings 8A and 9A in 3, the bearing components are shared and a part of the bearing surface is overlapped in the axial direction. The core 33 has a C-shaped longitudinal section so that an opening 33d is formed on the surface facing the spindle flange 4a, and the coil 35 is accommodated therein. The opening 33d is filled with a non-magnetic material. The core 33 has an assembling configuration of an inner peripheral core portion 33a and an outer peripheral core portion 33b having an L-shaped cross section in the illustrated example.
It may be one piece. The core 33 has a spacer 29 in the axial direction.
Are adjacent.

The thrust type hydrostatic gas bearings 8A and 9A are:
Hydrostatic bearing surfaces 8Aa, 9Aa formed on the side surface of the core 33 and forming a bearing clearance d2 with the spindle flange 4a.
And a restrictor 34a provided on the core 33 and opening on the hydrostatic bearing surfaces 8Aa and 9Aa. The throttle 34 a is provided at the tip of an air supply hole 34 opened on the outer diameter side surface of the core 33.

The bearing surfaces 8Aa and 9Aa of the thrust type hydrostatic magnetic bearings 8 and 9 are provided with a sprayed layer 61 of molybdenum or carbon, and the flanged surface of the main shaft 4 is provided with a sprayed layer 62 of ceramics. The thermal spray layers 61 and 62
The material may be such that the sprayed layer 61 on the bearing surface is made of ceramics, the sprayed layer 62 on the main shaft flange surface is molybdenum or carbon.

The thrust type magnetic bearings 8B and 9B are shown in FIG.
As shown in (1), there is a displacement detecting means 38 for detecting the displacement of the magnetic gap between the spindle flange 4a and the core 33. The displacement detecting means 38 may directly detect the amount of displacement, but in this example, the static pressure bearing gap d2
By detecting the static pressure of the magnetic gap, the detected pressure value is converted into a displacement amount to detect the displacement of the magnetic gap.
Specifically, the displacement detecting means 38 is composed of a pressure detection air passage 38a having a distal end opened in the static pressure bearing gap d2, and a sensor 38b communicating with the air passage 38a.

In the static pressure gas bearings 6A to 9A of the static pressure magnetic composite bearings 6 to 9 in FIG. 1, the air supply holes 24 and 34 are compressed from the air supply inlet 40a of the air supply hole 40 provided in the housing 5. Air or other compressed gas is supplied.

According to the spindle device 1 having this configuration, the sliding member 41 is provided in the vicinity of the main shaft 4, and the radial gap d
3 (FIG. 3) is smaller than the radial gap d between the hydrostatic gas bearing surfaces 6Aa and 7Aa of the radial type hydrostatic magnetic composite bearings 6 and 7, so that an excessive load is applied to the main shaft 4 and the main shaft 4 and the stationary side Mechanical contact between the sliding member 41 and the main shaft 4 is stopped. Further, since the sliding member 41 is made of carbon or graphite, the coefficient of friction is small. Therefore, the spindle device 1 does not damage the main shaft 4, the bearing surfaces 6Aa and 7Aa, and the sliding member 41 by the contact.

Since the static pressure gas bearing surfaces 6Aa and 7Aa are formed by the cores 23 of the magnetic bearings 6B and 7B, the bearing configuration is simplified. However, the material of the static pressure gas bearing surfaces 6Aa and 7Aa is a magnetic metal having no lubricity. And avoiding contact with the main shaft 4 is important. Therefore, it is effective to prevent the sliding member 41 from being damaged by receiving the main shaft 4. Further, since the sliding member 41 is disposed closer to the end of the main shaft than the arrangement of the hydrostatic magnetic composite bearings 6 and 7, even if the main shaft 4 is tilted due to an excessive radial load, the main shaft 4 can be securely fixed by the sliding member 41. The main shaft 4 is prevented from contacting the bearing surfaces 6Aa and 7Aa. The sliding material 41 has a hardness of 50 or more in shear hardness and a bending strength of 40 or more.
0 kgf / cm ² or more, compressive strength is 700 kgf / cm ² or more, and thermal expansion coefficient is 5 × 10 ^-6 or less, and a material having such hardness, bending strength, and compressive strength This prevents the sliding member 41 from being damaged when the main shaft 4 comes into contact. Further, by setting the coefficient of thermal expansion of the sliding member 41 within the above range, the magnetic bearings 6B, 6B,
The thermal expansion coefficient is equal to or less than that of the soft magnetic metal generally used for the 7B core 23, and the increase in the inner diameter due to the thermal expansion of the sliding member 41 is equal to or less than that of the core 23. for that reason,
Even if an excessive radial load acts on the main shaft 4 when the temperature rises, the sliding member 41 can reliably receive the load. Carbon and graphite can satisfy the above requirements for each material.

A gap d3 between the sliding member 41 and the main shaft 4 is a minute gap. Since the cooling gas is supplied to the gap by the cooling gas supply means 50, the main shaft due to the frictional heat of the air in the minute gap. 4 can suppress thermal expansion. Therefore, the main shaft 4 is prevented from thermally expanding and coming into contact with the sliding member 41. Since the cooling gas supply means 50 is constituted by the air supply holes 51 opened in the inner peripheral surface 41a of the sliding member 41, the cooling gas is efficiently supplied to the minute gap between the sliding member 41 and the main shaft 4 with a simple configuration. can do. Also, since the inner peripheral surface 41a of the sliding member 41 is a hydrostatic gas bearing surface,
The self-aligning action by the static pressure can be obtained even if the center of the shaft and the main shaft 4 are not accurately aligned. Therefore, the sliding material 4
When 1 is replaced, the minute gap between the main shaft 4 and the small eccentricity due to the mounting error does not become too small locally, and the replacement of the sliding member 41 becomes practically possible.

The thrust-type hydrostatic magnetic bearings 8 and 9 are provided with a sprayed layer 61 of molybdenum or carbon on the bearing surface and a sprayed layer 62 of ceramic on the flange surface of the main shaft. Of the thermal sprayed layers 61 and 62 are in contact with each other, and the sliding can provide protection. Further, since the thermal sprayed layers 61 and 62 are provided, unlike the case where the sliding material for touchdown protection is provided side by side with the hydrostatic magnetic composite bearings 8 and 9, the touchdown can be performed without increasing the diameter of the spindle flange. Time protection can be provided.

In the above embodiment, the cooling gas supply means 50 provided on the sliding member 41 is provided on the inner peripheral surface 41 of the sliding member 41.
The cooling gas supply means 50 supplies the cooling gas from outside the sliding member 41 to the gap between the sliding member 41 and the main shaft 4 as shown in FIG. 5, for example. The nozzle 51A may be used.

FIG. 6 shows a hydrostatic composite bearing spindle device 1A according to another embodiment of the present invention. In the example of FIG. 7, the same reference numerals are given to the portions corresponding to the embodiment of FIG. In this embodiment, a spindle drive device 10 is disposed between the radial type hydrostatic magnetic bearings 6 and 7 which support the main shaft 4, and the thrust type is located closer to the end than the hydrostatic magnetic bearing 7 behind. Hydrostatic magnetic composite bearing 8,
9 are arranged. The sliding member 41 is provided in the housing 5 at a position closer to the front end and the rear end than the arrangement of the static pressure magnetic composite bearings 6 to 9. Further, in this embodiment, the displacement detecting means 43, 4 of the hydrostatic magnetic composite bearings 6 to 9 are provided.
Reference numeral 4 denotes an eddy current sensor or the like that magnetically detects the displacement of the main shaft 4. The specific configuration of each of the hydrostatic magnetic composite bearings 6 to 9 in this embodiment is different from the example of FIG. 1, but all of them are the hydrostatic gas bearings 6A to 9A and the magnetic bearing 6B.
9B, and a part of the hydrostatic gas bearing surface is constituted by the electromagnet cores 23 and 33 of the magnetic bearings 6B to 9B. The relation between the radial gap of the sliding member 41 and the radial gap of each of the radial-type hydrostatic composite bearings 6, 7 in this embodiment, and the material of the sliding member 41 are the same as those in the embodiment of FIG. Further, the sliding member 41 is provided with a cooling gas supply means 50 as in the above embodiments. The cooling gas supply means 50 includes an air supply hole 51 opened on the inner peripheral surface of the sliding member 41 and an air supply path (not shown) for supplying air to the air supply hole 51.

In the above embodiment, the case of the hydrostatic magnetic composite bearing spindle device provided with the radial type hydrostatic magnetic composite bearings 6 and 7 has been described. However, the present invention is also applicable to the hydrostatic gas bearing spindle device. Can be. For example,
In the first embodiment shown in FIGS. 1 to 4, instead of the hydrostatic magnetic composite bearings 6 and 7, a hydrostatic gas bearing 66 may be provided as shown in FIG. In that case, the thrust type hydrostatic magnetic composite bearing 8,
9 (FIG. 1), a thrust type hydrostatic gas bearing (not shown) may be provided.

[0029]

According to the non-contact bearing spindle device of the present invention, in a spindle device in which a main shaft is supported by a radial type non-contact bearing, a sliding member close to the main shaft through a radial gap is installed. Provided in the housing, the radial gap of the sliding material is set to be equal to or less than the radial bearing gap of the non-contact bearing, and cooling gas supply means for supplying a cooling gas to the radial gap of the sliding material is provided. While using a non-contact bearing with a small bearing gap, it is possible to prevent the bearing and the spindle from being affected when the spindle is touched down, and to prevent the spindle from coming into contact with a sliding member for preventing the influence due to thermal expansion. When the cooling gas supply means has an air supply hole opened on the inner peripheral surface of the sliding material and a cooling gas supply path for supplying a cooling gas to the air supply hole, the cooling gas supply means can be slid with a simple configuration. The cooling gas can be efficiently supplied to the minute gap between the material and the main shaft. In this case, when the inner peripheral surface of the sliding member is a hydrostatic gas bearing surface, the strictness of the mounting accuracy of the sliding member is somewhat reduced due to the centering action by the static pressure gas, and the sliding member Can be exchanged. When the non-contact bearing is a hydrostatic / magnetic composite bearing, it becomes a compact bearing that takes advantage of the characteristics of both bearings, namely the excellent dynamic rigidity and rotational accuracy of the hydrostatic gas bearing, and the excellent static rigidity of the magnetic bearing. It becomes a compact spindle device with excellent performance.
A thrust type non-contact bearing for supporting the main shaft in a non-contact manner facing the flange formed on the main shaft is provided, and either a bearing surface of the thrust type non-contact bearing or a flange surface of the main shaft facing the bearing surface is provided. When a sprayed layer of molybdenum or carbon is provided on one surface, and a sprayed layer of ceramic is provided on the other surface of the bearing surface and the flange surface of the main shaft, wear resistance during touchdown in a thrust type non-contact bearing is provided. sex,
Sliding characteristics can be improved.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view of a spindle device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional front view of the spindle device.

FIG. 3 is an enlarged sectional view of a radial type hydrostatic magnetic composite bearing.

FIG. 4 is an enlarged sectional view of a thrust type hydrostatic magnetic composite bearing.

FIG. 5 is a partial sectional view of a spindle device according to another embodiment of the present invention.

FIG. 6 is a sectional view of a spindle device according to still another embodiment of the present invention.

FIG. 7 is a sectional view of a spindle device according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Spindle device 4 ... Main shaft 5 ... Housing 6-9 ... Static pressure magnetic compound bearing 6A-9A ... Static pressure gas bearing 6B-9B ... Magnetic bearing 6Aa, 7Aa ... Static pressure gas bearing surface 10 ... Spindle drive source 41 ... Slide Moving material 41a Inner peripheral surface 50 Cooling gas supply means 51 Air supply hole 52 Air supply path 53 Cooling gas supply source d Radial clearance of bearing d3 Radial clearance of sliding material

Claims (6)

[Claims] In a spindle device in which a main shaft is supported by a radial type non-contact bearing, a sliding member close to the main shaft via a radial gap is provided in a housing provided with the non-contact bearing. Wherein the radial gap is set to be equal to or smaller than the radial bearing gap of the non-contact bearing, and cooling gas supply means for supplying a cooling gas to the radial gap of the sliding member is provided. 2. The cooling gas supply means has an air supply hole opened on the inner peripheral surface of the sliding member, and a cooling gas supply passage for supplying a cooling gas to the air supply hole. Non-contact bearing spindle device. 3. The non-contact bearing spindle device according to claim 2, wherein the inner peripheral surface of the sliding member is a static pressure gas bearing surface for supporting a main shaft with static pressure by gas discharged from the air supply hole. 4. The non-contact bearing is a radial type hydrostatic compound bearing in which a hydrostatic gas bearing and a magnetic bearing are compounded, and the radial gap of the sliding member is formed by the hydrostatic compound bearing. The non-contact bearing spindle device according to any one of claims 1 to 3, wherein the radial bearing clearance is set to be equal to or less than a radial bearing gap between the static pressure gas bearing and the magnetic bearing. 5. The non-contact bearing spindle device according to claim 1, wherein the non-contact bearing is a hydrostatic gas bearing. 6. A thrust type non-contact bearing for supporting the main shaft in a non-contact manner facing a flange formed on the main shaft, a bearing surface of the thrust type non-contact bearing and a main shaft facing the bearing surface. 6. A sprayed layer of molybdenum or carbon is provided on one of the flange surfaces, and a sprayed layer of ceramic is formed on the other surface of the bearing surface and the flange surface of the main shaft. A non-contact bearing spindle device according to claim 1.