JP2000074066A - Rotor supporting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To insure supporting rigidity without increasing the rotational load to a rotational member by supplying liquid into a thrust bearing space, and supplying compressed air into a bearing space. SOLUTION: Water is supplied to a thrust bearing space 133 by a liquid supply means 140, water films are formed on the upper face, the lower face, and the like of a flange 122 for thrust bearing to form a liquid static pressure bearing. Meanwhile, compressed air is supplied between the outer circumferential face of a shaft part 121 and the inner circumferential face of a main body 131 forming the bearing space 134 of a rotational member 130, the air layer of compressed air is formed between the outer circumferential face of the shaft part 121 and the inner circumferential face of the main body 131 to form an air static pressure bearing. By this constitution, since the thrust bearing flange 122 is borne with the liquid static pressure bearing, supporting rigidity can be insured. In the shaft part 121, the rotational member 130 is borne with the air static pressure bearing to reduce the rotational load of the rotational member 130.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating body supporting device for rotatably supporting a rotating member or the like on which a grinding wheel of a surface grinding device is mounted.

[0002]

2. Description of the Related Art As is well known to those skilled in the art, in a semiconductor device manufacturing process, the surface of a semiconductor wafer is ground to form a substantially disk-shaped semiconductor wafer to a predetermined thickness. Such a surface grinding apparatus that grinds the surface of a semiconductor wafer uses a rotating body support method that supports a rotating member using a hydrostatic bearing in order to reduce a rotating load of a rotating member on which a grinding wheel is mounted. Have been. A so-called air spindle using compressed air is generally used as a rotating body support device using a hydrostatic bearing. Even if the compressed air leaks, it does not affect other devices, so that it is easy to handle. However, there is a problem that the rigidity of supporting the rotating member is insufficient.

In order to solve the above problem, a rotating body supporting apparatus using a hydrostatic bearing using a liquid is disclosed in Japanese Patent Laid-Open No. 63-2 / 1988.
No. 16673. The rotating body support device disclosed in this publication includes a rotating member having a thrust bearing space formed by closing one end, a bearing space formed continuously with the thrust bearing space and one end and the other end being opened, A fixed main shaft having a shaft portion fitted into the bearing space and a thrust bearing flange provided at one end of the shaft portion and housed in the thrust bearing space is provided. A liquid supply passage and a liquid return passage are formed in the fixed main shaft and open to the thrust bearing space and the bearing space, respectively. The liquid supply passage supplies liquid to the bearing space and the thrust bearing space through the liquid supply passage. The hydrostatic bearing is formed by collecting the liquid through the return passage. As described above, in the rotating body supporting device that forms a hydrostatic bearing using a liquid, the supporting rigidity of the rotating member can be ensured.

[0004]

However, the rotating body supporting device disclosed in Japanese Patent Application Laid-Open No. 63-216673 has a so-called air spindle using compressed air since it forms a liquid hydrostatic bearing. Therefore, there is a problem that the viscous resistance is higher than that of the above, the rotational load of the rotating member increases, and a drive loss occurs. Also, if the liquid leaks, it must be securely sealed to affect other devices, and an annular ring made of synthetic rubber is provided between the inner peripheral surface of the open end of the rotating member and the outer peripheral surface of the shaft of the fixed main shaft. However, friction occurs because the seal member slides on the rotating member, which increases the rotational load of the rotating member and causes a large drive loss.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and a main technical problem thereof is to provide a rotating body supporting device capable of securing supporting rigidity without increasing a rotating load of a rotating member. It is in.

[0006]

According to the present invention, there is provided a thrust bearing space formed by closing one end, and a thrust bearing space formed continuously with one end and the other end formed according to the present invention. And a fixed main shaft having a thrust bearing flange provided at one end of the shaft portion and accommodated in the thrust bearing space. In the rotating body supporting apparatus, there is provided a rotating body supporting apparatus, comprising: liquid supply means for supplying liquid to the thrust bearing space; and compressed air supply means for supplying compressed air to the bearing space. You.

The liquid supply means includes a liquid supply passage and a liquid return passage formed in the fixed main shaft and opening to the thrust bearing space, and a liquid supply source for supplying liquid to the liquid supply passage. The air supply means includes an air passage formed in the fixed main shaft and opening to the bearing space, and a compressed air supply source for supplying compressed air to the air passage.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a rotating body supporting device according to an embodiment of the present invention;

FIG. 1 is a perspective view of a surface grinding device equipped with a rotating body supporting device constructed according to the present invention, and FIG. 2 is a grinding diagram equipped with a rotating body supporting device constructed according to the present invention. The principal part sectional drawing of a grindstone assembly is shown. The surface grinding device provided with the rotating body support device in the illustrated embodiment includes a support base 2. A support table 4 is provided on the support base 2 so as to be rotatable in a horizontal plane. The support table 4 is formed in a disk shape having a relatively large diameter, and is appropriately rotated in a direction indicated by an arrow 4a by a drive mechanism (not shown). On the support table 4, two workpiece holding chucks 6 are arranged rotatably in a horizontal plane with a phase angle of 180 degrees in the illustrated embodiment. This work holding chuck 6
For example, a suction-fixed chuck for suction-fixing a workpiece to an upper surface of a chuck by suction as described in JP-A-61-182838 is used. The two workpiece holding chucks 6 arranged on the support table 4 are alternately positioned in the work area A and the grinding area B by rotating the support table 4 in the direction indicated by the arrow 4a. The work area A is an area for taking out and mounting the work piece 8 such as a semiconductor wafer. The work piece 8 whose surface has been ground in the work area A is taken out of the work holding chuck 6 by an appropriate take-out means (not shown). Then, a new workpiece 8 whose surface is to be ground is placed on the workpiece holding chuck 6 by an appropriate mounting means (not shown). A grinding wheel assembly 10 is provided in the grinding area B, and the workpiece 8 held on the workpiece holding chuck 6 is ground by a grinding wheel described later of the grinding wheel assembly 10. You. At this time, the workpiece holding chuck 6 is rotated in a direction indicated by an arrow 6a by a drive mechanism (not shown).

Next, the grinding wheel assembly 10 will be described with reference to FIG. The grinding wheel assembly 10 is
It is mounted on a stationary support plate 22 erected from the end of the support base 2 on the grinding area B side so as to be vertically movable. Guide rails 221 and 221 extending in the vertical direction are provided on the surface of the stationary support plate 22 on the side of the support table 4, and a vertically moving block 24 is mounted on the guide rails 221 and 221 so as to be movable in the vertical direction. I have. The grinding wheel assembly 10 is attached to the vertical motion block 24 by an appropriate fixing means. The vertical motion block 24 is moved in the vertical direction by a screw drive mechanism (not shown) using a pulse motor 26 as a drive source.

The grinding wheel assembly 10 in the illustrated embodiment includes a spindle holder 110 mounted on the vertical motion block 24 by a suitable fixing means. The spindle holder 110 has a holder cover 111 formed in a cylindrical shape from the lower surface thereof.
Is provided. The grinding wheel assembly 10 in the illustrated embodiment includes a fixed spindle 120 disposed through the center of the holder cover 111, and a rotating body rotatably supported on the fixed spindle 120 based on the outer periphery thereof. Is provided. Fixed spindle 120
Is a shaft portion 121 and a disk-shaped thrust bearing flange 1 provided at one end (a lower end in FIG. 2) of the shaft portion 121.
The other end (the upper end in FIG. 2) of the shaft portion 121 is fixed to the spindle holder 110 by an appropriate fixing means.

In the illustrated embodiment, the rotating member 130 has a cylindrical main body 131 and one end of the main body 131 (FIG. 2).
At the lower end). The main body 131 is provided with a thrust bearing space 133 for accommodating the thrust bearing flange 122 at one end (the lower end in FIG. 2), and is formed continuously with the thrust bearing space 133 at the other end (see FIG. 2). Bearing space 134 whose upper end is opened in FIG.
Is provided. The main body 131 thus configured
The shaft portion 121 of the fixed main shaft 120 is placed in the bearing space 134.
And the thrust bearing flange 122 is accommodated in the thrust bearing space 133. And
By attaching the grindstone support member 132 to one end (the lower end in FIG. 2) of the main body 131 with a plurality of fixing bolts 135, the lower end of the thrust bearing space 133 is closed. Note that a grindstone base 136 is attached to the lower surface of the grindstone support member 132 by several fixing bolts 137, and the grindstone 138 is annularly mounted on the lower surface of the grindstone base 136. The rotating member 130 thus configured is configured to be rotationally driven by the permanent magnet electric motor 200 in the illustrated embodiment. The permanent magnet electric motor 200 includes a permanent magnet 201 mounted on an outer peripheral surface of a main body 131 and a stator 202 disposed around the permanent magnet 201 and mounted on an inner peripheral surface of a holder cover 111 of the spindle holder 110. By feeding power to the stator 202,
The rotation member 130 is driven to rotate. In the illustrated embodiment, an example is shown in which a permanent magnet type electric motor is incorporated as a driving unit of the rotating member 130, but it goes without saying that another driving unit may be used.

The rotating member 130 configured as described above
Are mounted on the fixed main shaft 120 by a hydrostatic bearing and an aerostatic bearing. Next, the liquid supply means 140 for supplying a liquid for forming a hydrostatic bearing will be described. The liquid supply unit 140 includes a supply pump 141 serving as a liquid supply source.
And a recovery pump 142 and a liquid passage formed in the fixed main shaft 120. Shaft portion 121 and thrust bearing flange 122 constituting the fixed main shaft 120
, A plurality of liquid supply passages 143 and one liquid return passage 144 are formed. This liquid supply passage 143 is
The shaft portion 121 is formed in the axial direction, and the thrust bearing flange 122 is formed in the radial direction. The thrust bearing flange 122 is provided with the liquid supply passage 14.
3, a plurality of throttle passages 145 are formed on the upper and lower surfaces of the flange 122, and annular pockets 146 and 146 are formed on the upper and lower surfaces of the flange 122 so as to pass through the openings of the throttle passage 145. I have. The liquid return passage 144 is formed so as to penetrate the axis of the shaft portion 121 and the thrust bearing flange 122. A plurality of return passages 147 communicating with the liquid return passage 144 and opening on the outer peripheral surface of the flange 122 are formed in the thrust bearing flange 122. Further, a return support passage 148 communicating with the liquid return passage 144 and opening on the outer peripheral surface of the shaft 121 is formed at the lower end of the shaft 121. The liquid supply passage 143 is connected to a supply pump 141 via an appropriate pipe, and is connected to the liquid return passage 14.
4 is connected to the recovery pump 142 via an appropriate pipe. The supply pump 141 has a discharge pressure of 1 to 1.5 million Pascal (about 10 to 15
Atmospheric pressure) is used. In the illustrated embodiment, the example in which the liquid return passage 144 is connected to the recovery pump 142 is shown. However, the recovery pump 142 is not necessarily required, and the liquid return passage 144 is directly connected to a liquid tank (not shown). Is also good.

Next, the compressed air supply means 150 for supplying compressed air for forming an aerostatic bearing will be described. The compressed air supply means 150 includes an air compressor 151 serving as a compressed air supply source and the fixed main shaft 120.
And an air passage formed in the air passage. The air passage includes a plurality of air supply passages 15 formed in the fixed main shaft 120 in the axial direction.
2, air ejection passages 153a and 153b formed in communication with the air supply passage 152 and opening on the outer peripheral surface, and a shaft portion 1 with the air ejection passages 153a and 153b opened.
21 includes annular pockets 154a and 154b formed on the outer peripheral surface of the air conditioner 21. The air supply path 152 is connected to the air compressor 151 via an appropriate pipe. The air ejection passage 153a and the pocket 154a
The air ejection passage 153b and the pocket 154b are formed at predetermined intervals in the axial direction (vertical direction in FIG. 2). In the illustrated embodiment, the fixed spindle 12
The air return passage 155 provided in the shaft 121 of the No. 0, a return branch 156 formed in communication with the air return passage 155 and opening to the outer peripheral surface, and the shaft 121 having the return branch 156 opened. An annular pocket 157 formed on the outer peripheral surface is provided. The opening of the return branch 156 and the pocket 157 correspond to the air ejection passage 153a and the pocket 154a and the air ejection passage 153b and the pocket 154.
b. In the illustrated embodiment, the air compressor 151 having a discharge pressure of about 500,000 to 600,000 Pascal (about 5 to 6 atm) is used.

The liquid supply means 14 configured as described above
The operation of the hydrostatic bearing and the hydrostatic bearing formed by the zero and compressed air supply means 150 will be described. The liquid supply means 140 uses water as a liquid in the illustrated embodiment. The water discharged from the supply pump 141 is sent from the liquid supply passage 143 to the annular pocket 146 through the throttle passage 145 formed in the thrust bearing flange 122, and the thrust bearing flange 12
2 flows out between the upper surface and the lower surface of the rotating member 130 and the lower surface of the main body 131 forming the thrust bearing space 133 of the rotating member 130 and the upper surface of the grinding wheel support member 132. As a result, the upper and lower surfaces of the thrust bearing flange 122 and the body 13
1 and the upper surface of the grinding wheel support member 132
A degree of water film is formed. In this manner, the water that has flowed into the thrust bearing space 133 returns to the return support passage 147 and the shaft 1 formed in the thrust bearing flange 122.
The liquid is returned to the liquid return passage 144 through a lower return support passage 148 formed in the liquid storage 21, and is recovered by a liquid tank (not shown) via a recovery pump 142. in this way,
Since the thrust bearing flange 122 is a hydrostatic bearing, the support rigidity can be ensured.

On the other hand, the compressed air discharged from the air compressor 151 is supplied from the air supply passage 152 to the air ejection passage 1.
Annular pocket 154a through 53a and 153b
And 154b, and flows out between the outer peripheral surface of the shaft portion 121 and the inner peripheral surface of the main body 131 forming the bearing space 134 of the rotating member 130. As a result, an air layer of compressed air is formed between the outer peripheral surface of the shaft portion 121 and the inner peripheral surface of the main body 131. Therefore, in the shaft portion 121, the rotating member 130 is subjected to aerostatic bearing. Since air has a lower viscous resistance than liquid, the rotational load of the rotating member 130 is small, and driving loss can be reduced. Further, the air that has formed the air layer between the outer peripheral surface of the shaft portion 121 and the inner peripheral surface of the main body 131 as described above is returned to the air return passage 155 through the return branch passage 156 and discharged to the outside. At the same time, a part thereof is discharged to the outside from the open end (the upper end in FIG. 2) of the main body 131 of the rotating member 130. In addition,
Even if air leaks to the outside, it does not affect other devices, so it functions as an air seal, and there is no need to attach a seal member made of synthetic rubber or the like. There is no increase. In addition, since a sealing member made of synthetic rubber or the like is not used, deterioration over time does not occur, and therefore, the sealing function can be maintained for a long time. In the illustrated embodiment, an example in which the air return passage 155 is provided in the shaft portion 121 has been described, but the return branch passage 15 is provided without providing the air return passage 155.
6 may be configured to communicate with the liquid return passage 144.

As described above, an example is shown in which the rotating body supporting device constructed according to the present invention is applied to a surface grinding device. However, the present invention is not limited to this, and the rotating body supporting device using a hydrostatic bearing is used. It can be widely applied to

[0018]

The rotating body supporting device according to the present invention is constructed as described above, and the features of the hydrostatic bearing and the features of the aerostatic bearing are skillfully combined with each other.

That is, according to the present invention, since the flange portion for the thrust bearing of the fixed main shaft is a hydrostatic bearing, it is possible to secure the supporting rigidity. Further, since the shaft portion of the fixed main shaft is aerostatic bearing, air has a lower viscous resistance than the liquid, so that the rotational load of the rotating member is small and the driving loss can be reduced. Furthermore, even if air leaks to the outside, there is no effect on other devices, so there is no need to attach a seal member made of synthetic rubber or the like, so that there is no increase in rotational load due to sliding contact of the rotary member with the seal member. In addition, since a sealing member made of synthetic rubber or the like is not used, deterioration over time does not occur, and therefore, the sealing function can be maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a perspective view of a surface grinding device equipped with a rotating body support device configured according to the present invention.

FIG. 2 is a sectional view of a main part of a grinding wheel assembly equipped with a rotating body support device configured according to the present invention.

[Explanation of symbols]

 2: Support base 4: Support table 6: Workpiece holding chuck 8: Workpiece 10: Grinding stone assembly 22: Stationary support plate 24: Vertically moving block 26: Pulse motor 110: Spindle holder 111: Holder cover 120 : Fixed spindle 121: Shaft of fixed spindle 122: Flange for thrust bearing of fixed spindle 130: Rotating member 131: Main body of rotating member 132: Grinding stone support member 133: Thrust bearing space 134: Bearing space 135: Fixed bolt 136: Grinding Whetstone 140: Liquid supply means 141: Supply pump 142: Recovery pump 143: Liquid supply path 144: Liquid return path 145: Restriction path 146: Annular pocket 147: Return support path 148: Return support path 150: Compressed air supply means 151 : Air compressor 152: Air supply path 15 a: air ejection passage 153b: air ejection passage 154a: annular pocket 154b: annular pocket 155: air return passage 156: Return 支通 path 157: annular pocket 200: permanent magnet motor 221: guide rail

Claims (2)

[Claims] 1. A thrust bearing space formed by closing one end, a rotating member having a bearing space formed continuously with the thrust bearing space and one end and opened at the other end, and fitted with the bearing space. A rotating body support device comprising: a shaft portion; and a fixed main shaft provided at one end of the shaft portion and having a thrust bearing flange housed in the thrust bearing space; and a liquid supply means for supplying a liquid to the thrust bearing space. A compressed air supply means for supplying compressed air to the bearing space;
A rotating body support device comprising: 2. The liquid supply means includes a liquid supply passage and a liquid return passage formed in the fixed main shaft and opening to the thrust bearing space, and a liquid supply source for supplying liquid to the liquid supply passage. The rotating body according to claim 1, wherein the compressed air supply means includes an air passage formed in the fixed main shaft and opening to the bearing space, and a compressed air supply source for supplying compressed air to the air passage. Support device.