JPH11303867A - Composite hydrostatic and magnetic bearing and spindle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact bearing having excellent dynamic rigidity and rotational accuracy which are owned by a hydrostatic bearing, and excellent static rigidity which is owned by a magnetic bearing. SOLUTION: A radial type bearing 1 comprises a static bearing 2 and a magnetic bearing 3 which are integrally incorporated with each other, having a part commonly used by both bearings. The center line of a coil 7 in the magnetic bearing 7 is laid substantially in parallel with the axial direction of a rotor 4a. Nozzles 15 for pressure fluid in the hydrostatic bearing 2 are arranged axially with respect to the coil 7. The magnetic bearing 3 is composed of a pair of yoke coupling bodies 12, 12 and a core component 8 wound thereon with the coil 7 and interposed between the pair of yoke coupling bodies 12, 12. The yoke coupling bodies 12, are composed of yokes 9 serving as a part of the core 6 and interference-fitted in holes formed in a ring-like nonmagnetic body 11 at several circumferential positions, and between the inner peripheral frings of the opposed surface of the both yoke coupling bodies are embedded with the separate non-magnetic material body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrostatic / magnetic composite bearing in which a hydrostatic bearing and a magnetic bearing are combined, a method of manufacturing the bearing, and a spindle device equipped with the bearing, such as a high-speed cutting machine. And a spindle device used for

[0002]

2. Description of the Related Art Magnetic bearings have a large bearing gap so that the torque loss due to rotation is extremely small, and a large static rigidity can be imparted by integral control. However, the magnetic bearing spindle device is easily affected by the bending natural frequency of the spindle during machining,
Therefore, it is necessary to configure a very complicated control system. Therefore, it is not suitable as a spindle device for a general-purpose machine tool which needs to cope with various processing conditions. On the other hand, non-contact bearings include hydrostatic bearings in addition to magnetic bearings. A hydrostatic bearing has extremely high rotational accuracy and excellent dynamic stability, but has a small static rigidity and a low load capacity due to its compressibility, and has almost no application to general-purpose machine tools.

Therefore, as a spindle device for a high-speed processing machine, a composite bearing spindle device combining a hydrostatic bearing 101 and a magnetic bearing 102 has recently been proposed as shown in a longitudinal sectional view of FIG. Is being considered. In the composite bearing spindle device shown in the figure, since the magnetic bearing 101 and the hydrostatic bearing 102 are arranged side by side in the axial direction,
There is a problem that the main shaft 103 becomes longer and the natural frequency of bending becomes lower. In addition, since the control system configuration is exactly the same as that of the spindle device that uses the magnetic bearing alone, the dynamic stability of the hydrostatic bearing is impaired, and it acts as a source of disturbance. There are points. Therefore, at present, the purpose of making up for the disadvantages while making use of the features of the hydrostatic bearing and the magnetic bearing has not been sufficiently achieved.

In order to solve such a conventional problem, as shown in FIG. 1 (B), a hydrostatic bearing 104 and a hydrostatic bearing, in which a hydrostatic bearing and a magnetic bearing are integrated so as to form a shared portion, are provided. A spindle device using the bearing 104 was considered. The hydrostatic magnetic composite bearing 104 of this proposed example has a bearing gap forming surface 106 of a hydrostatic bearing with a magnetic bearing core 105.
And a core 107 is provided with a nozzle 107 for pressurized fluid. The core 105 is provided at a plurality of positions in the circumferential direction of the main shaft 103, and the coil 108 has a center axis
03 is provided so as to be perpendicular to the axial direction. According to this, a bearing having excellent dynamic rigidity and rotational accuracy of the hydrostatic bearing and excellent static rigidity of the magnetic bearing can be obtained, and the spindle length can be reduced. However, in the magnetic circuit composed of the core 105 and the main shaft 103, the current generated at the time of high-speed rotation cannot be reduced, so that further improvements are required in terms of magnetic circuit formation, compactness, and the like. As a specific configuration of the radial type hydrostatic magnetic composite bearing, the present inventor provided a yoke 49 divided into four parts in the circumferential direction as shown in FIG. 9 as one of the embodiments in this specification. Suggested ones. Since the surface on which the hydrostatic bearing acts needs to eliminate a gap through which air leaks, a resin (non-magnetic material) 51 is filled between the yokes 49, and then the inner surface grinding is performed.
However, in the bearing shown in the figure, the temperature of the yoke 49 and the resin 51 rises due to heat generated by the motor due to rotation of the spindle and heat generated by the magnetic bearing due to magnetic levitation. In response to this temperature rise, the resin 51 has a coefficient of thermal expansion that is about one digit greater than that of the yoke 49, so that the resin 51 forms a raised portion 51a on the surface of the yoke 49 as shown in FIG. It has a significant effect on pressure bearing performance. The resin 5
Instead of 1, a non-magnetic metal member 51 (FIG. 12) is manufactured by machining to match the gap between the yokes 51, 51,
Although an insertion method is conceivable, it is very difficult to eliminate the gap to such an extent that the performance of the hydrostatic bearing is not affected.

FIG. 16 shows an example of a proposal of a hydrostatic composite bearing applied to an axial bearing. In this example, the spindle 110
, A hydrostatic magnetic composite bearing 111 is provided so as to face the flange-shaped bearing rotor portion 110a. Hydrostatic magnetic composite bearing 11
1 is provided with an annular core 112 having a U-shaped cross section whose width surface serves as a bearing gap forming surface 114 of the hydrostatic bearing.
2, a coil 113 is provided, and a nozzle 115 is provided at an inner diameter of the core 112. As a specific configuration of the axial type, as shown in FIG. 10 as one of the embodiments in this specification, a core 25 is divided into an inner diameter side core part 26 and an outer diameter side core part 27, and a hydrostatic bearing is provided. In order to eliminate the gap between the surfaces, a material in which a resin (nonmagnetic material) 65 is filled between the core components 26 and 27 has been proposed. However, also in the axial bearing, similarly to the radial bearing, there is a problem that the performance of the hydrostatic bearing is reduced due to the thermal expansion of the resin and the generation of the gap. That is, in the bearing of FIG. 10, the temperature of the core 25 and the resin 65 rises due to heat generated by the motor due to rotation of the spindle and heat generated by the magnetic bearing due to magnetic levitation. In response to this temperature rise, the resin 65 has a coefficient of thermal expansion that is about one digit greater than that of the core 25.
As shown in FIG.
a, which greatly affects the performance of the hydrostatic bearing. Instead of the resin 65, a method of manufacturing and inserting a nonmagnetic metal member 28A (FIG. 14) corresponding to the gap between the core components 26 and 27 by machining may be considered. It is very difficult to eliminate the gap to the extent that it does not affect.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a problem, and to combine the excellent dynamic rigidity and rotational accuracy of a hydrostatic bearing with the excellent static rigidity of a magnetic bearing, thereby achieving a more compact hydrostatic magnetic bearing. And a spindle device provided with the bearing. Another object of the present invention is to stabilize the performance of preventing a bearing gap of a hydrostatic bearing from fluctuating due to a rise in the temperature of a bearing portion and preventing unnecessary fluid leakage from the bearing gap due to an assembly error or the like. And a simple manufacturing method thereof.

[0007]

The hydrostatic / magnetic composite bearing of the present invention is constructed by combining a hydrostatic bearing and a magnetic bearing in a predetermined relationship. For this reason, it is possible to obtain a bearing that takes advantage of the characteristics of both the excellent dynamic rigidity and rotational accuracy of the hydrostatic bearing and the excellent static rigidity of the magnetic bearing. In this case, the hydrostatic composite bearing according to claim 1 is a radial type bearing in which the hydrostatic bearing and the magnetic bearing are integrated so as to form a shared portion, and a center line of a coil of the magnetic bearing is set to a rotor. And the nozzle of the pressure fluid of the hydrostatic bearing is provided in the axial direction with respect to the coil. As described above, when the dual-purpose part is provided for the hydrostatic bearing and the magnetic bearing, the configuration becomes compact as compared with a case where the hydrostatic bearing and the magnetic bearing are simply arranged side by side in the axial direction.
The rotor length can also be reduced. This makes it a rotor,
Alternatively, the bending natural frequency of the main shaft on which the rotor is provided is increased, and higher-speed rotation becomes possible. Further, since the center line of the coil is substantially parallel to the axial direction of the rotor, the required magnetic force can be secured even if the coil is miniaturized, and the size can be further reduced.

In the radial bearing according to the present invention, the magnetic bearing includes a plurality of electromagnets arranged in a circumferential direction on an outer periphery of a rotor, and a core of each of the electromagnets is arranged in an axial direction of the rotor. The cross-sectional shape is C-shaped, the opening thereof faces the rotor side, and the opening is filled with a non-magnetic material, and the space between each core adjacent in the circumferential direction is filled with a non-magnetic material. The core may be provided with the nozzle. In the case of this configuration, since the opening of the core is filled with the non-magnetic material, this opening can also be used as a bearing gap forming surface of the hydrostatic bearing.

In the radial bearing of the present invention, a pair of yokes, which are part of an electromagnet core, are fitted in a plurality of circumferential holes formed in a ring-shaped non-magnetic body in a tightly fitted state. A yoke assembly is provided, these yoke assemblies are arranged in the axial direction, a core component having a coil wound around the outer periphery is interposed between the opposed yokes of the two yoke assemblies, and an inner peripheral edge of an opposing surface of the two yoke assemblies is provided. The space is filled with a non-magnetic material, the inner diameter surface of the magnetic material and the inner diameter surface of the yoke combination are used as a bearing gap forming surface of a hydrostatic bearing, and the yoke is provided with a nozzle that opens to the bearing gap forming surface. It is good. In this configuration, since the yoke is attached in a tightly fitted state to the hole formed in the non-magnetic material, it is easy to completely fill the space between the yokes adjacent in the circumferential direction without any gap. In addition, a material having a small coefficient of linear expansion such as a metal material can be selected as the non-magnetic material.
Fluctuations in the bearing gap can be reduced with respect to a rise in the temperature of the bearing portion, and performance of the hydrostatic bearing can be maintained. In addition, assembling can be easily performed while the gap between the yokes is completely eliminated.

According to the method of manufacturing a radial type hydrostatic composite bearing of the present invention, a non-magnetic material having a plurality of yoke fitting holes arranged in a circumferential direction is prepared, and the respective yoke fitting holes of the non-magnetic material are prepared. A step of fitting the yoke to the non-magnetic body in a tightly fitted state, and forming a cylindrical hole in a state where the yoke is exposed at the center of the non-magnetic body, and forming a ring-shaped yoke coupling body comprising the non-magnetic body and a plurality of yokes And a pair of yoke assemblies processed in this way are arranged in the axial direction, and a core component having a coil wound around its outer periphery is interposed between the opposed yokes of the two yoke assemblies, and the two yoke assemblies are connected. Filling the gap between the inner peripheral edges of the opposing surfaces of the body with another non-magnetic material, wherein the inner diameter surface of the cylindrical hole of the yoke coupling body and the inner diameter surface of the another non-magnetic material form a bearing gap of the hydrostatic bearing. Surface and opens to this bearing clearance forming surface Nozzle is a method of producing a combined externally pressurized gas and magnetic bearing assembly which is formed on the yoke. As described above, a pair of yoke coupling bodies in which the yokes are fitted in the holes provided in the non-magnetic material in a tightly fitted state are manufactured, and assembled using the yoke coupling bodies, the circumference can be easily assembled by a simple assembling method. The gap between the yokes adjacent in the direction can be completely eliminated, and the hydrostatic magnetic composite bearing having various excellent bearing performances as described above can be easily manufactured.

In this bearing manufacturing method, after the step of fitting the yoke into the respective yoke fitting holes of the non-magnetic material in a tightly fitted state, or in a state where the yoke is exposed at the center of the non-magnetic material, the cylindrical hole is formed. After the step of forming a ring-shaped yoke combination comprising the non-magnetic material and a plurality of yokes,
The non-magnetic material and the yoke may be joined by welding.

According to a sixth aspect of the present invention, there is provided a hydrostatic magnetic composite bearing, wherein the hydrostatic bearing and the magnetic bearing are axial type bearings integrated so as to form a dual-purpose part. A ring-shaped electromagnet core facing the width surface, the core having an opening facing the width surface side of the rotor;
It has a U-shaped cross-section, its opening is filled with a non-magnetic material, a coil is provided in the core, and a nozzle for a pressure fluid of a hydrostatic bearing is provided in the core. Also in the case of this configuration, the configuration becomes compact as compared with the case where the hydrostatic bearing and the magnetic bearing are simply arranged side by side in the radial direction.

In the axial type of the present invention, the core is divided into two parts: an inner diameter side core part extending from the opening to the inner diameter side; and an outer diameter side core part extending from the opening to the outer diameter side. The ring-shaped non-magnetic member provided in the opening is tightly fitted to both the surface on which the opening of the inner core component and the surface of the opening of the outer core component are tightly fitted. And the nozzle may be provided on the inner diameter side component.
As described above, the core is divided into two parts, and the ring-shaped non-magnetic material is attached to the opening of the core in a tight fit state.
The opening of the core can be easily and completely filled with the nonmagnetic material without any gap. In addition, a material having a small linear expansion coefficient, such as a metal material, can be selected as the non-magnetic material that fills the opening, so that the bearing gap can be prevented from changing even when the temperature rises.
The performance of the hydrostatic bearing can be maintained.

A method of manufacturing an axial type hydrostatic composite bearing according to the present invention is a core part which is combined with each other to form a ring-shaped electromagnet core having a C-shaped cross section in a magnetic bearing, A step of preparing an inner diameter side core component extending to the inner diameter side, and an outer diameter side core component extending from the opening to the outer diameter side, and forming the opening forming surface of the inner diameter side core component, and an outer diameter side core component. These inner diameter side core components, so that the ring-shaped non-magnetic material is sequentially fitted to both of the formation surfaces of the opening in a tight fit state,
Assembling an outer diameter side core component and a non-magnetic material, wherein the core faces the width surface of the rotor at the opening-side width surface and the opposing surface and the surface of the non-magnetic material are hydrostatic bearings. A method of manufacturing a hydrostatic magnetic composite bearing which has a nozzle for a pressure fluid which serves as a clearance forming surface and which is provided on the inner diameter side core component and opens to the bearing clearance forming surface. The ring-shaped non-magnetic body may be fitted first to either the inner diameter side core part or the outer diameter side core part. According to this method, the core is divided into two parts, and the ring-shaped non-magnetic material is attached to the opening of the core in a tight-fit state, so that the opening of the core can be easily and completely filled with the non-magnetic material without any gap. . Further, the ring-shaped non-magnetic material is fitted to one of the inner diameter side core part and the outer diameter side core part, and then is fitted to the inner side core part and the outer diameter side core part so as to be fitted to the other. The ring-shaped non-magnetic body can be easily fitted to both the inner and outer core parts by a simple operation. Therefore, it is possible to easily produce an axial type hydrostatic composite bearing having various excellent bearing performances as described above. In this bearing manufacturing method, a ring-shaped non-magnetic material is fitted in a tightly fitted state on the surface of the opening of the outer-diameter core component in a tight fit state, and then the outer-diameter core component and the non-magnetic material are joined by welding. Alternatively, the outer diameter side core part and the inner diameter side core part to which the non-magnetic material is joined may be assembled in a fitted state.

The hydrostatic / magnetic composite bearing spindle device of the present invention is such that the main shaft including the rotor is rotatably supported by the housing via any of the hydrostatic / magnetic composite bearings of the present invention. According to this configuration, large static rigidity, excellent dynamic stability and rotational accuracy can be obtained, and the main shaft can be shortened and the bending natural frequency of the main shaft can be increased. Is possible. In addition, the overall size can be reduced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. The hydrostatic composite bearing 1 according to the present embodiment is obtained by integrating a hydrostatic bearing 2 and a magnetic bearing 3 in a radial bearing so that a dual-purpose part is formed. The bearing rotor 4a has a part of the main shaft 4 having a length. The bearing rotor 4 a may be formed separately from the main shaft 4 and attached to the main shaft 4. A plurality (four in the illustrated example) of electromagnets 5 of the magnetic bearing 3 are provided in the circumferential direction. Each electromagnet 5 includes a core 6 and a coil 7, and each coil 7 is connected to a power supply 10. The core 6 includes a linear core component 8 around which a coil 7 is wound, and a pair of yokes 9, 9 sandwiched from both ends of the core component 8. The cross-sectional shape along the axial direction of the main shaft 4 is the same as that of the main shaft 4. It has a C-shape with an opening at the bottom. Core component 8 and yoke 9
Are each made of a ferromagnetic material. The core component 8 is in the shape of a round bar, but may be in the shape of a square bar.

The plurality of yokes 9 arranged in the circumferential direction are combined with the non-magnetic body 11 (FIG. 1B) together with the ring-shaped yoke coupling body 1.
Constituting No. 2. That is, the yoke 9 is fitted into the yoke fitting holes 13 formed at a plurality of positions in the circumferential direction formed in the ring-shaped nonmagnetic body 11 in a tightly fitted state to form the yoke combined body 12. The yoke coupling body 12 has a cylindrical hole 12b formed at the center thereof so as to penetrate therethrough. Each yoke 9 has a shape in which a portion serving as the cylindrical hole 12a is cut out from a disk-shaped body or a columnar body, and the yokes 9 which are circumferentially adjacent to each other are formed.
The portion between the yoke fitting holes 13, 13 of the non-magnetic body 11 is interposed between them. The yoke assembly 12 has a flange 12 a formed on one side of the inner peripheral edge and formed by a part of the yoke 9 and the nonmagnetic material 11. The yoke coupling body 12 includes a flange 12
A pair is provided in the axial direction so that a and 12a face each other. Collar part 12 of both yoke combination bodies 12
The space between a and 12a is filled with another non-magnetic material 14. The non-magnetic member 14 has a cylindrical shape, and has the same inner and outer diameters as the flange portion 12a. Each of the non-magnetic members 11 and 14 has
Metallic materials are used.

The inner diameter surfaces of the two yoke coupling bodies 12 and the non-magnetic body 14 between them constitute a bearing gap forming surface 2 a of the hydrostatic bearing 2. Each of the yokes 9 of the two yoke coupling bodies 12, 12 is provided with a nozzle 15 that opens to the bearing gap forming surface 2a. The nozzle 15 is formed by a hole penetrating the yoke 9 in the radial direction of the main shaft 4. The nozzle 15 is, for example,
Two coils are provided on each yoke 9 so as to be located symmetrically on both sides of the coil 7. The number of the nozzles 15 may be any number, and the position of the nozzles 15 can be provided irrespective of the coil 7. The nozzle 15 may have a throttle (not shown).

FIG. 2 shows a manufacturing process of the yoke assembly 12. A thick disk-shaped nonmagnetic body 11A in which a plurality of yoke fitting holes 13 formed of round holes are equally arranged in the circumferential direction is prepared (FIG. 1A). A yoke material 9A made of a columnar magnetic material is fitted into each yoke fitting hole 13 of the non-magnetic material 11A in a tight-fit state by press-fitting or shrink-fitting (FIG. 1B). Non-magnetic body 11 fitted with this yoke material 9A
A is machined by turning or the like, and a boss 12
The disk is shaped like a disk with a boss protruding from c (FIG. (C)). The outer diameter of the boss 12c is the outer diameter that will later become the flange 12a. A cylindrical hole 12b is formed in the center of this boss-shaped disk-shaped workpiece.
To form a yoke combination body 12 (FIG. 2D).
The inner diameter surface of the cylindrical hole 12b is finished by grinding or the like. FIG. 3E is a plan view of the completed yoke combination 12. The yoke assembly 12 is assembled with other components after processing the nozzle 15 (FIG. 1). This assembly
As shown in FIG. 3, the core component 8 around which the coil 7 is wound is sandwiched between the yokes 9, 9 of the pair of yoke coupling bodies 12, 12 manufactured as described above.
Cylindrical non-magnetic body 1 between opposed flanges 12a, 12a
4. The non-magnetic member 14 is joined to the flange 12a of the one yoke coupling body 12, and in this state, each core component 8 is sandwiched between the yoke coupling bodies 12, 12. As shown in FIG. 7, the non-magnetic body 11 and the yoke 9 may be connected to the yoke unit 12 by welding 19.

Since the hydrostatic magnetic composite bearing 1 is a combination of the hydrostatic bearing 2 and the magnetic bearing 3 as described above, the excellent dynamic rigidity of the hydrostatic bearing 2 and the excellent static rigidity of the magnetic bearing 3 are provided. A bearing that takes advantage of both features. Since the hydrostatic bearing 2 and the magnetic bearing 3 are also used as constituent components, the configuration is more compact and the length of the main shaft 4 is shorter than when the hydrostatic bearing and the magnetic bearing are simply arranged side by side in the axial direction. It can also be shortened. As a result, the bending natural frequency is increased, and higher-speed rotation becomes possible. The yoke 9 of the magnetic bearing 3 also serves as a member for forming the bearing gap d of the hydrostatic bearing 2,
And since the yoke 9 also serves as a forming member of the nozzle 15,
The components are highly shared and the effect of making the configuration compact is high. Further, since the yoke 9 is attached in a tightly fitted state to the hole 13 formed in the non-magnetic body 11, the gap between the yokes 9 adjacent in the circumferential direction is completely non-magnetic as compared with each embodiment described later. The body 11 is easy to fill, and the effect of the temperature rise of the bearing portion on the bearing performance is small. In addition, assembling can be easily performed while the gap between the yokes 9 is completely eliminated.

FIGS. 4 and 5 show an embodiment in which the present invention is applied to an axial bearing. The hydrostatic / magnetic composite bearing 21 is obtained by integrating a hydrostatic bearing 22 and a magnetic bearing 23 such that a portion that also serves as each other is formed. The bearing rotor 4 b includes a flange-shaped portion provided on the main shaft 4. The magnetic bearing 23 has a ring-shaped electromagnet core 25 facing the width surface of the rotor 4b. The core 25 has a C-shaped cross section, and the C-shaped opening 25a is provided on the width surface side of the rotor 4b. Orientation, filled with non-magnetic material 28. A coil 29 is provided in the core 25. The coil 29 is provided so that its center line is parallel to the axial direction of the rotor 4b, and is connected to a power supply 30. The core 25 is made of a ferromagnetic material, and the non-magnetic material 28 is made of a metal material. The static pressure bearing 22 is provided with a bearing gap forming surface 31 facing the width surface of the rotor 4b by the core 25 and the non-magnetic material 28, and a pressure fluid nozzle 32 opening in the bearing gap forming surface 31. The nozzle 32 is connected to an air supply source (not shown). Bearing gap forming surface 3
1 is finished by grinding.

The core 25 has a C-shaped opening 25a.
An inner diameter side core component 26 extending from the inner side to an inner diameter side;
and an outer-diameter core component 27 extending from a to the outer-diameter side. The non-magnetic body 28 is formed in a ring shape, and is formed on both the surface on which the opening 25a of the inner diameter side core component 26 is formed and the surface on which the opening 25a of the outer diameter side core component 27 is formed. By press fit or shrink fit, they are fitted in an interference fit state. The inner diameter side core component 26 includes a ring-shaped plate portion 26a (FIG. 5D), an inner cylindrical portion 26b protruding from an inner diameter edge of the ring-shaped plate portion 26a, and an outer diameter side from a tip of the inner cylindrical portion 26b. And a front end of the flange 26c is a surface on which the opening 25a is formed. The coil 29 is installed on the inner surface of the ring-shaped plate portion 26a of the inner core member 26. The nozzles 32 are formed as holes penetrating in the axial direction through the inner cylindrical portion 26b of the inner diameter side core component 26, and are arranged at a plurality of positions in the circumferential direction. The outer diameter side core component 27 is formed of an outer cylindrical portion 27b (see FIG.
(A) and a flange portion 27c extending from the tip of the outer cylindrical portion 27b toward the inner diameter side, and the tip of the flange portion 27c is a surface on which the opening 25a is formed. The outer cylindrical portion 27b has the same outer diameter as the outer diameter of the ring-shaped plate portion 26a of the inner-diameter-side core component 26, and abuts against the inner peripheral portion of the ring-shaped plate portion 26a.

FIG. 5 shows the assembling process of the axial type hydrostatic composite bearing 21. The non-magnetic member 28 is attached to the inner diameter surface of the flange portion 27c of the outer diameter side core component 27 by press fitting or shrink fitting. The outer diameter side core part 27 and the non-magnetic body 28
Is assembled with the inner core part 26 on which the coil 29 is installed. In this case, the non-magnetic member 28 is assembled by press-fitting or shrink-fitting the flange 26c of the inner core member 26. Thus, the hydrostatic composite bearing 21 is assembled as shown in FIG. In addition,
The nozzle 32 is machined on the inner diameter side core component 26 before assembly. Also, as shown in FIG.
After the non-magnetic member 28 is press-fitted or shrink-fitted on the inner diameter surface of the flange portion 27c, the two parts 27, 28 may be joined by welding 33.

As described above, also in the case of an axial bearing, the core 25 and the non-magnetic member 28 of the magnetic bearing 23 are also used as components of the bearing clearance forming surface 31 of the hydrostatic bearing 22, and the core 25 is used as the nozzle 32. The configuration is compact because it is also used as a component. Further, the core 25 is divided into two parts, and a ring-shaped nonmagnetic material 2 is formed in the opening 25a of the core 25.
8 are sequentially fitted in a tight fit state, so that the opening of the core 25 can be easily and completely closed without any gap.
Can be filled with

FIG. 6 shows a hydrostatic composite bearing spindle device according to an embodiment of the present invention. This spindle device comprises two sets of radial type hydrostatic magnetic composite bearings 81, 8
1, two sets of axial type hydrostatic composite bearings 82, 82 disposed between both bearings 81, 81, and a motor 83 for rotating the main shaft 4 are installed in a housing 84. The motor 83 is installed behind a portion supported by the bearings 81 and 82. Two sets of axial type hydrostatic composite bearings 82, 82 are arranged facing both surfaces of the same rotor 4b formed on the main shaft 4,
One set of hydrostatic magnetic composite bearings 82 may be arranged on only one side of the rotor 4b. Each of the bearings 81 and 82 is connected to an air pressure source (not shown) via a common air supply path 85 provided in a housing 84. Each of the hydrostatic and magnetic composite bearings 81 and 82 may be any hydrostatic and magnetic composite bearing according to the present invention. The bearings 1 and 21 of the above-described embodiments may also be used. May be.
Also, bearings 81, 82 constituting the spindle device
However, it is not always necessary to use the hydrostatic composite bearing as a whole, and the hydrostatic composite bearing according to the present invention may be used for any one of them.

As described above, by employing the spindle device using the hydrostatic composite bearing of the present invention, a large static rigidity, excellent dynamic stability and rotational accuracy can be obtained, and the main shaft 4 can be shortened. Since the bending natural frequency of the main shaft 4 is increased, it can be put to practical use as a spindle device for a general-purpose high-speed processing machine. Further, the entire device can be made compact.

FIG. 9 shows a radial type hydrostatic composite bearing according to another embodiment of the present invention. The hydrostatic magnetic composite bearing 41 is the same as the hydrostatic magnetic composite bearing 1 according to the embodiment of FIG.
9 is a fan-shaped yoke 49 as shown in FIG. 9 (B), and a non-magnetic body 51 is interposed between the yokes 49, 49 adjacent in the circumferential direction. The non-magnetic material 51 is made of a resin, and is formed by filling a molten resin between the yokes 49, 49 arranged at predetermined intervals. Thus, a yoke combined body 52 in which the yoke 49 and the non-magnetic body 51 are integrated is formed. The inner diameter surface 52b serving as the bearing gap forming surface 22 of the yoke coupling body 52 is ground after the non-magnetic material 51 made of resin is hardened. Other configurations are the same as those in the example of FIG. 1, and corresponding portions are denoted by the same reference numerals and description thereof will be omitted. Even with this configuration, the magnetic circuit is formed neatly,
The respective effects described in the embodiment of FIG. 1 can be obtained. However,
In the case of this embodiment, due to the difference in thermal expansion between the yoke 49 and the resin non-magnetic material 51 when the temperature rises, as shown in exaggerated manner in FIG. A protruding raised portion 51a may occur. Since the raised portion 51a affects the bearing gap, it is necessary to devise control of the hydrostatic bearing.

In the example shown in FIG. 9, the non-magnetic material 51 is made of non-magnetic metal instead of resin, and the yokes 49, 4
It may be manufactured by machining in accordance with the shape of the gap between the holes 9 and inserted between the yokes 49. According to this, the problem of swelling when the temperature rises is solved. However, when the non-magnetic member 51 is made of a metal member, it is difficult to process the metal member with high precision. Therefore, as illustrated in an exaggerated manner in FIG. 12, an extra gap e is generated between the non-magnetic member 51 and the yoke 49. Sometimes. It is sufficient that the gap e does not affect the bearing gap d, but in order to do so, the nonmagnetic body 51 and the yoke 49 need to be processed with high precision. The embodiment shown in FIG. 1 solves the problem of the occurrence of the bulges 51a and the extra gap e, improves the assemblability of the bearing, and stabilizes the bearing performance of the hydrostatic bearing.

FIG. 10 shows an axial type hydrostatic composite bearing according to still another embodiment of the present invention. The static pressure magnetic composite bearing 61 is the same as the static pressure magnetic composite bearing 21 according to the embodiment of FIG. 4 except that the core 25 is filled with a resin nonmagnetic material 65 instead of tightly fitting the nonmagnetic material 28. It is. The non-magnetic material 65 is filled until it becomes flush with the surface of the core 25, and the surfaces of the core 25 and the non-magnetic material 65 that become the bearing gap forming surfaces 31 are ground. Other configurations are the same as the embodiment of FIG. Also in the case of such a configuration, each effect described in the embodiment of FIG. 4 can be obtained, for example, the magnetic circuit b is formed beautifully.
However, also in this embodiment, as shown in FIG. 13, there is an effect on the bearing gap d due to the raised portion 65a of the non-magnetic body 65 when the temperature rises, and a countermeasure is required.

In the embodiment shown in FIG. 4, instead of assembling the inner core part 26 and the outer core part 27 after press-fitting or shrink-fitting the non-magnetic body 65 into the outer core part 27, Core part 26 and outer core part 2
7 and the opening 25a of the core 25 in a state where
Alternatively, an assembling method of inserting the ring-shaped non-magnetic body 28A into the housing may be adopted. However, in this case, it is difficult to insert the non-magnetic body 65 without a gap, and as shown in an exaggerated manner in FIG. 14, an extra gap f may be formed in communication with the bearing gap d. Affect. Therefore, as described with reference to FIG.
It is preferable to assemble the inner diameter side core component 26 and the outer diameter side core component 27 after press fitting or shrink fitting.

[0031]

As described above, the hydrostatic composite bearing and the spindle device according to the present invention are a combination of a hydrostatic bearing and a magnetic bearing in a predetermined relationship, so that the hydrostatic bearing has excellent dynamic rigidity and rotational accuracy. The structure becomes compact while having both the excellent static rigidity of the magnetic bearing. In the case of a radial bearing, the spindle length can also be reduced. According to the method of manufacturing a hydrostatic magnetic composite bearing of the present invention, the gap between the yokes can be easily eliminated in a simple assembly process,
Stability of bearing performance can be achieved.

[Brief description of the drawings]

FIG. 1A is a sectional view of a radial type hydrostatic magnetic composite bearing according to an embodiment of the present invention, and FIG. 1B is a cutaway plan view thereof.

FIG. 2 is an explanatory diagram of a manufacturing process of a yoke assembly in the hydrostatic magnetic composite bearing.

FIG. 3 is a perspective view showing an assembling method of the hydrostatic magnetic composite bearing.

FIG. 4A is a cutaway side view of an axial-type hydrostatic composite bearing according to another embodiment of the present invention, and FIG. 4B is a cutaway plan view of the same.

FIG. 5 is an explanatory diagram of an assembly process of the bearing.

FIG. 6 is a sectional view of a hydrostatic magnetic composite bearing spindle device according to an embodiment of the present invention.

FIG. 7 is a perspective view showing a modification of the yoke assembly in the embodiment of FIG. 1;

FIG. 8 is a cross-sectional view showing a modification of the outer diameter side core component and the non-magnetic material in the embodiment of FIG. 4;

FIG. 9A is a sectional view of a radial type hydrostatic composite bearing according to still another embodiment of the present invention, and FIG. 9B is a cutaway plan view thereof.

FIG. 10A is a cross-sectional view of an axial type hydrostatic composite bearing according to still another embodiment of the present invention,
(B) is a cutaway plan view thereof.

FIG. 11 is a cutaway plan view showing a problem of the embodiment of FIG. 9;

FIG. 12 is a cutaway plan view showing a problem of still another embodiment.

FIG. 13 is a cutaway side view showing a problem of the embodiment of FIG. 10;

FIG. 14 is a cutaway side view showing a problem of still another embodiment.

FIG. 15A is a sectional view of a conventional spindle device,
(B) is a sectional view of a spindle device according to a comparative proposal example.

FIG. 16 is a cutaway side view of an axial-type hydrostatic composite bearing according to a comparative proposal example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 2 ... Static pressure bearing 12 ... Yoke coupling body 2a ... Bearing gap formation surface 14 ... Non-magnetic material 3 ... Magnetic bearing 15 ... Nozzle 4 ... Main shaft 22 ... Static pressure bearing 4a ... Rotor 23 ... Magnetic bearing 4b ... Rotor 25 ... Core 5 ... Electromagnet 26 ... Inner diameter core part 6 ... Core 27 ... Outer diameter side core part 7 ... Coil 28 ... Non-magnetic material 8 ... Core part 29 ... Coil 9 ... Yoke 31 ... Bearing gap forming surface 11 ... Non-magnetic material 32 ... Nozzle

Claims (10)

[Claims] 1. A radial type bearing in which a hydrostatic bearing and a magnetic bearing are integrated so as to form a dual-purpose part.
A hydrostatic magnetic composite bearing in which a center line of a coil of the magnetic bearing is substantially parallel to an axial direction of a rotor, and a nozzle of a pressure fluid of the hydrostatic bearing is provided in the axial direction with respect to the coil. 2. The magnetic bearing includes a plurality of electromagnets arranged in a circumferential direction on an outer periphery of a rotor, and a core of each of the electromagnets has a C-shaped cross section along an axial direction of the rotor. It is assumed that the opening faces the rotor side, the opening is filled with a non-magnetic material, the space between each core adjacent in the circumferential direction is filled with a non-magnetic material, and the nozzle is provided in each core. The hydrostatic magnetic composite bearing according to claim 1. 3. A pair of yoke coupling bodies in which a yoke, which is a part of an electromagnet core, is fitted in a plurality of circumferential holes formed in a ring-shaped non-magnetic body in a tightly fitted state. The joined bodies are arranged in the axial direction with each other, and a core component having a coil wound around the outer periphery is interposed between the opposed yokes of the two yoke joined bodies. The inner surface of the other non-magnetic material and the inner surface of the yoke combination are used as a bearing gap forming surface of a hydrostatic bearing, and the yoke is provided with a nozzle that opens to the bearing gap forming surface. Static magnetic composite bearing. 4. A step of preparing a non-magnetic material having a plurality of yoke fitting holes arranged in a circumferential direction, fitting a yoke into each of the yoke fitting holes of the non-magnetic material in a tight fit state, and A step of forming a cylindrical hole in a state where the yoke is exposed at the center of the magnetic body to form a ring-shaped yoke combination body composed of the non-magnetic body and a plurality of yokes; The yoke joints are arranged in the axial direction, a core component having a coil wound on the outer periphery is interposed between the opposed yokes of the two yoke joints, and another non-magnetic material is provided between the inner peripheral edges of the opposing surfaces of the two yoke joints. The inner diameter surface of the cylindrical hole of the yoke coupling body and the inner diameter surface of the other non-magnetic material serve as a bearing gap forming surface of the hydrostatic bearing. Radial type static pressure magnetic duplex formed on yoke A bearing manufacturing method for manufacturing joint bearings. 5. The bearing manufacturing method according to claim 4, wherein
After the process of fitting the yoke in the respective yoke fitting holes of the non-magnetic material in a tight fit state, or by forming the cylindrical hole in a state where the yoke is exposed at the center of the non-magnetic material, the non-magnetic material is formed. A method of manufacturing a bearing in which a non-magnetic body and a yoke are joined by welding after a step of forming a ring-shaped yoke combination body including a plurality of yokes. 6. An axial type bearing in which a hydrostatic bearing and a magnetic bearing are integrated so as to form a dual-purpose part, wherein the magnetic bearing has a ring-shaped electromagnet core facing a width surface of the rotor, The core has a C-shaped cross section with an opening facing the width side of the rotor, the opening is filled with a non-magnetic material, a coil is provided in the core, and the pressure of the hydrostatic bearing is applied to the core. Axial-type hydrostatic magnetic composite bearing with a fluid nozzle. 7. The core is divided into an inner diameter core component extending from the opening to the inner diameter side and an outer diameter core component extending from the opening to the outer diameter side. The ring-shaped non-magnetic body provided in the opening is fitted in both the formation surface of the opening portion and the formation surface of the opening portion of the outer diameter side core component in an interference fit state, and the inner diameter side component is The hydrostatic magnetic composite bearing according to claim 6, wherein the nozzle is provided in the bearing. 8. A core part which is combined with each other to form a ring-shaped electromagnet core having a C-shaped cross section in a magnetic bearing, wherein the inner core part extends from an opening in the C-shaped cross section to an inner diameter side. And a step of preparing an outer diameter core component extending from the opening to the outer diameter side, and both a forming surface of the opening of the inner diameter core component and a forming surface of the opening of the outer diameter core component. Assembling the inner diameter side core part, the outer diameter side core part, and the non-magnetic body so that the ring-shaped non-magnetic bodies are sequentially fitted in a tight fit state. The surface of the non-magnetic body facing the width surface of the rotor on the side of the width side is the bearing gap forming surface of the hydrostatic bearing, and the pressure fluid that opens to the bearing gap forming surface on the inner diameter side core component is formed. Has nozzle Production method for producing an axial type hydrostatic magnetic bearing. 9. The method for manufacturing a bearing according to claim 8, wherein
After the ring-shaped non-magnetic material is fitted in a tightly fitted state on the surface of the opening of the outer-diameter core component in a tight fit state, these outer-diameter core components and the non-magnetic material are joined by welding, and the non-magnetic A bearing manufacturing method for assembling a joined outer diameter core part and an inner diameter core part in a fitted state. 10. A hydrostatic magnet in which a main shaft including the rotor is rotatably supported on a housing via a hydrostatic magnetic composite bearing according to claim 1, 2 or 3, or 6 or 7. Composite bearing spindle device.