JPH0861367A - Spindle device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a spindle device in which the conduction state (earth) and the insulation state of a rotating body can be freely selected and set as necessary. [Structure] The housing 10 has a rotary shaft 20 with a static pressure gas bearing 1
2 is a spindle device in which a conductive elastic member 50 attached to a lid 45 fixed to one end of the housing 10 presses one end surface of the rotating shaft 10 and the lid 45 is non-conductive. The elastic member 50 was attached to the lid 45 via a conductive bolt 51 penetrating the lid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a spindle device which can be suitably used for inspection equipment such as an MR head inspection machine.

[0002]

2. Description of the Related Art Conventionally, as a spindle device used for inspecting and measuring magnetic disks and the like, for example, Japanese Patent Laid-Open No.
There is one disclosed in Japanese Patent No. 218889. In this type, a spindle, which is a rotating shaft, is supported by a cylindrical housing via a static pressure gas bearing, and a conductive brush attached to a lid fixed to one end of the housing has one of the rotating shafts. It is designed to press the end faces. The rotary shaft is hollow, and the other open end face of the rotary shaft is a vacuum suction surface.

A magnetic disk is adsorbed and held on the vacuum adsorption surface, and predetermined processing and inspection are performed while removing electrical noise with a brush, which is an advantage that a rotary joint unlike a general vacuum adsorption spindle device is not required. There is.

[0004]

However, for example, in the case of a magnetic disk, it is necessary that the spindle (rotating body) for holding and rotating the magnetic disk and its housing (fixed body) be held in the same potential conductive state. Not only the inspection but also the inspection that needs to be held in a state of being insulated from the housing (fixed body). However, in the above conventional example,
The housing that makes up the spindle, the lid at the end,
Since the rotating shaft is also made of a conductive material, the rotating shaft that holds the magnetic disk and the housing of the fixed body become electrically conductive and have the same potential, so it cannot be used for inspection while holding the device in an insulated state. There is a problem.

Therefore, the present invention has been made by paying attention to the above-mentioned conventional problems, and can be freely set by selecting either the conductive state (ground) or the insulated state of the rotating body as required. An object is to provide a spindle device.

[0006]

According to the present invention, a rotating shaft is supported by a housing through a static pressure gas bearing, and a conductive elastic member attached to a lid fixed to one end of the housing is rotated. According to a spindle device for pressing one end surface of a shaft, the lid includes a non-conductive member, and an elastic member is attached to the lid via a conductive bolt penetrating the non-conductive member. It is a thing.

[0007]

A conductive elastic member elastically contacted with the rotary shaft is fixed by a conductive bolt through a non-conductive lid provided at one end of the housing, and the conductive bolt and the housing are connected to each other. Is connected by a conducting member, the rotating shaft and the housing are brought into a conducting state, and if the conducting member is removed, the two are brought into an insulating state.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are sectional views of an embodiment of the present invention.
The whole is divided into three parts in the axial direction. The left end of the figure is the static pressure air bearing part 1, the middle part is the motor part 2, and the right end is the encoder part 3.

First, the structure will be described. The static pressure air bearing portion 1
The housing 10A, which is a fixed body, has a cylindrical shape (the outer shape may be a square shape), and is fixedly supported by a fixing member (not shown) via a mounting flange 11. A rotary shaft 20 is rotatably supported inside the housing 10A. The rotary shaft 20 has a hollow cylindrical shape having a through hole 20a in its shaft portion, and flange-like collar portions 21 and 22 are respectively screwed to the shaft ends by bolts B so as to be detachable. The flange portion 22 facing the motor unit 2 side has a shaft 20 extending through the shaft centers of the motor unit 2 and the encoder unit 3.
A is extended to form an extension of the rotary shaft 20. The other flange portion 21 is provided so as to project from the end face of the housing 10A, has a through hole 23 communicating with the hollow hole 20a at the center, and has a circular recess 24 on the outer end face to open to adsorb a workpiece. The holding portion 25 is configured.

Both ends of the housing 10A are cut out in an annular shape, and two short cylindrical porous members 12, 12 constituting a static pressure gas bearing are adhered or tightly fitted to the inner peripheral surface thereof. They are fixed axially at intervals by means. The porous member 12 is made of porous graphite or the like, and is finished by cutting or grinding so that the inner peripheral surface is used as the radial bearing surface 12R and the outer end surface is used as the thrust bearing surface 12S. On the other hand, each collar 2 of the rotary shaft 20
The thrust receiving surfaces 21S, 22 whose inner surfaces are flat
S, and the thrust bearing is formed so as to face the thrust bearing surface 12S in a non-contact manner with a slight bearing gap.

On the other hand, the radial bearing surface 1 of the porous member 12
2R is opposed to the radial receiving surface 20R on the outer peripheral surface of the rotary shaft 20 via a radial bearing clearance in the radial direction, and the radial receiving surface 20R and the radial bearing surface 12R constitute a radial bearing. Then, from the outer peripheral surface of the housing 10A to the annular air supply chamber 14 on the outer periphery of each porous member 12, 12.
A compressed air from a pressurized gas supply source (not shown) is supplied to the compressed air from a compressed gas supply source (not shown) and is ejected into the radial and thrust bearing gaps through the porous member 12 functioning as a throttle. Forming a rotary shaft 2
0 is levitationally supported in a non-contact manner with respect to the housing 10A.

The porous members 1 at both ends of the housing 10A
Grooves 15, 1 continuous in the circumferential direction are provided at three positions on the inner circumferential surface located between the Nos. 2 and 12 at intervals in the axial direction.
6, 17 are formed. Out of these grooves, the grooves 15 and 17 located at positions adjacent to the porous member 12 are provided with exhaust holes 18 communicating with the outside in the radial direction and opened to the outer surface of the housing 10. Further, at least one exhaust hole 19 is provided in the groove 16 at the intermediate position on the outer side in the radial direction so as to be opened to the outer surface of the housing 10A, and the threaded portion of the opening end thereof is provided with a pipe of a vacuum pump (not shown) (a magnetic disk is a vacuum chuck). Instead of this, when using the piston or the like to chuck the rotary shaft 20, a compressed air supply pipe) is connected. On the other hand, in the hollow rotary shaft 20, in alignment with the groove 16 at the intermediate position provided in the housing 10A,
A plurality of air intake holes 26 penetrating in the radial direction are provided.

The motor section 2 has a housing 10B.
Is coaxially fixed to the housing 10A of the hydrostatic air bearing portion 1 with a bolt (not shown), and the brushless DC motor 30 is built therein. That is, the motor stator 31 having the armature coil 32 is fixed to the inner diameter surface of the housing 10B. On the other hand, the rotor 35, which faces the stator via an air gap, includes a rotor yoke 33 and a magnet 34, and is fixedly attached to the outer diameter surface of the extension portion 20A of the rotary shaft 20. A lid 36 made of a conductive material is fixed to the housing 10B of the motor unit 2 by a bolt B on the end surface on the right end side in the drawing. The extension 20A of the rotary shaft is inserted into the through hole 37 at the center of the lid 36.

The encoder unit 3 has a housing 1 thereof.
0C is coaxially fixed to a lid 36 fixed to the housing 10B of the motor unit 2 with a bolt B, and includes, for example, a completely non-contact rotary encoder 40 as a rotational position sensor of the rotary shaft 20. ing. That is, a disk-shaped slit plate 41 is integrally rotatably attached to the outer diameter surface of the extension portion 20A of the rotary shaft 20, and the slit plate 41 and a fixed index (not shown) are provided through a gap between the light projecting / receiving element 42, It is arranged so as to be sandwiched by 43.

A lid 45 made of a non-conductive material such as synthetic resin is attached to the end of the housing 10C of the encoder portion 3 with a metal bolt 46. By the way, the housing 10 which is a component other than the lid 45.
(Housing 10A, 10B, 10C), rotary shaft 20,
The extension portion 20A, the collar portions 21, 22 and the like are conductive members made of metal or the like. Further, a contactor 47 is arranged at the end of the extension 20A of the rotary shaft 20, and the leaf spring 4 is attached to the contactor 47.
8, an elastic conductive member 50 composed of the ground pad 49 is pressed. The contactor 47 preferably has a convex spherical surface with a small radius of curvature in order to prevent wear of the ground pad 49, and a ball is used in this embodiment. The leaf spring 4
8 is fixed to a non-conductive lid 45, which is a ground pad fixing base, by conductive bolts 51 and nuts 52, and is electrically isolated from the housing 10, which is a fixed body. However, the head of the bolt 51 is exposed on the outer surface of the lid 45, and one end of the metal short-circuit plate 53 is attached and tightened to the bolt 51 as shown in FIG. 3, and the other end is screwed to the housing 10. By attaching to the lid fixing bolt 46, the rotary shaft 20 and the housing 10 are electrically conductive through the contact 47, the elastic conductive member 50, the bolt 51, the short-circuit plate 53, and the lid fixing bolt 46. 3 shows the other bolt 51A adjacent to the one conductive bolt 51 for fixing the short-circuit plate 53, the other bolt 51A can be omitted.

Next, the operation will be described. Explaining the case of use as an MR head inspection machine, a magnetic disk (not shown) is attached to the workpiece suction holder 25 at the tip of the rotary shaft 20, and a vacuum pump (not shown) is operated to move the recess 2
4. The magnetic disk is suction-held by sucking the air in the through hole 20a through the suction hole 26, the groove 16, and the suction hole 19.

Next, the brushless motor 30 is started to rotate the magnetic disk together with the rotary shaft 20 at a constant rotational speed. Various inspections are performed by bringing an MR head (not shown) applying a magnetoresistive element close to the rotating magnetic disk. When inspecting a magnetic disk with this MR head, the potential of the magnetic disk is required. Therefore, the short-circuit plate 53 is not set at the end of the spindle device, and the leaf spring 48 is conducted to the MR head so that the MR head and the magnetic disk have the same potential via the rotary shaft 20.

On the other hand, in the case of the inspection in which the leaf spring 48 is not electrically conductive to the MR head, the short-circuit plate 53 is previously set at the end of the spindle device, and the fixed housing 10 and the rotating magnetic disk are the same. Set to potential. In this way, the electric potential of the magnetic disk attached to the rotary shaft 20 can be freely set and can be used for various inspections.

The operation of the static pressure air bearing portion 1 is as follows. Air supply hole 1 opened on the outer peripheral surface of the housing 10A
A pressurized gas from a pressurized gas supply source (not shown) connected to the porous material 1 is passed through the air supply hole 13 and the air supply chamber 14 to each porous member 1
It is sent to 2 and 12, respectively. The pressurized gas passes through the inside of the porous member 12, is divided into a radial bearing surface 12R and a thrust bearing surface 12S, and is ejected at a uniform pressure and flow rate into the radial bearing clearance and the thrust bearing clearance to form a fluid film. To support the rotary shaft 20 in the radial direction and the thrust direction in a non-contact manner. In this case, in the thrust bearing clearance, the thrust bearing surfaces 12S on both end surfaces of the porous members 12, 12 are provided.
Since the pressure gas is directly ejected from, the thrust bearing rigidity and load capacity close to the design value can be obtained.

The gas ejected from the thrust bearing surface 12S is discharged to the outside through the gap between the thrust bearing surface 12S and the collar portion 21 of the rotary shaft. In addition, a part of the gas ejected from the radial bearing surface 12R and the thrust bearing surface 12S and the flange portion 2 of the rotary shaft are included.
While being discharged to the outside through the gap between the first and second holes, the remaining portion is discharged to the outside from the exhaust hole 18 through the grooves 15 and 17 adjacent to the porous member 12 on the intermediate inner diameter surface of the housing 10A.

In the case of this embodiment, the rotation of the rotary shaft 20 is controlled by feeding back the detection signal of the rotary encoder 40 to a controller (not shown) of the brushless motor 30 to ensure accurate rotation of the magnetic disk. However, the present invention is also applicable to a rotary encoder that does not necessarily have a rotation sensor. Also,
An electric wire may be used instead of the short-circuit plate 53 of the above embodiment.

Further, the porous member 12 of the above-mentioned embodiment is prepared by impregnating the outer peripheral surface layer of the core portion made of a graphite material having pores with, for example, phenol resin so as to block the material pores. A surface stop layer may be provided. Further, the air supply chamber 14 provided on the outer periphery of the porous member 12 may be provided on the housing 10A side.

Further, the grooves 15, 16 and 17 provided on the inner peripheral surface of the housing 10A may be provided toward the rotary shaft 20,
Alternatively, it may be provided separately on the inner peripheral surface of the housing 10A and the outer peripheral surface of the rotary shaft 20. Further, although the static pressure gas bearing of the above-mentioned embodiment shows the case where the porous member is used, other types, for example, a multi-hole static pressure gas bearing provided with an orifice throttle or a self-made throttle, or a surface It is also possible to use a diaphragm-type static pressure gas bearing.

[0024]

As described above, according to the spindle device of the present invention, the rotating shaft is supported by the housing which is the fixed body through the static pressure gas bearing, and the non-conductive material is provided at one end of the housing. Since a lid made of is attached, and one end face of the rotary shaft is elastically pressed by a conductive elastic member fixed with a conductive bolt penetrating the cover, the rotary shaft and the housing are temporarily insulated, In addition, the conductive bolt and the housing are short-circuited by a short-circuit member so that they are electrically connected. In this way, it is possible to freely insulate the fixed body from the rotary shaft or to make them the same potential, and set the potential of the rotary shaft freely according to the inspection contents of the inspected object mounted on the rotary shaft. The effect that it can be used for the inspection of.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

2 is another cross-sectional view of one embodiment of the present invention (FIG. 1)
Is omitted, and the viewing direction is changed).

FIG. 3 is a rear view.

[Explanation of symbols]

 10 Housing 10A Housing 10B Housing 10C Housing 12 Porous Member 45 Lid 50 Elastic Conductive Member 51 Conductive Bolt

Claims (1)

[Claims] 1. A rotary shaft is supported by a housing via a static pressure gas bearing, and a conductive elastic member attached to a lid fixed to one end of the housing presses one end face of the rotary shaft. In the spindle device, the lid includes a non-conductive member, and the elastic member is attached to the lid through a conductive bolt that penetrates the non-conductive member.