JP3333714B2 - Flat grinding machine using fluid bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface polishing apparatus in which a surface plate is supported by a fluid bearing, and more particularly, a work surface is rotated by rotating a surface plate supported by a fluid bearing in both forward and reverse directions. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forward / reverse processing type flat polishing apparatus for polishing.

[0002]

2. Description of the Related Art In a planar polishing apparatus such as a lapping machine or a polishing machine, a work may be polished by rotating a surface plate in both forward and reverse directions. As an example, for example, in a device for polishing a work made of a hard brittle material such as a glass or other ceramic magnetic disk substrate using a pellet surface plate in which a large number of polishing pellets are attached to a work surface, Since the shaved chips are likely to adhere to the abrasive grains of the pellets and cause clogging, the platen is reversed every fixed polishing time to peel off the chips, thereby eliminating clogging and removing the work. I try to polish. This is based on the principle that when the surface plate is rotated in one direction and polished, the chips retained on one side of the abrasive grains are separated from the abrasive particles by rotating the surface plate in the reverse direction, eliminating clogging. Ru der those utilizing.

[0003] On the other hand, in a planar polishing apparatus, a fluid bearing may be used to support a thrust load on a surface plate (for example, see Japanese Patent Publication No. 61-54444).
As shown in FIG. 7, the fluid bearing generally includes an annular oil tank 1 containing an appropriate amount of lubricating oil 3, an annular floating ring 2 attached to a surface plate, and a lower end fitted into the oil tank 1. 8 and 9 on the inner bottom surface of the oil tank 1.
As shown in the figure, the dynamic pressure generating groove 4 having a gentle slope 4a is cut. When the floating ring 2 rotates in the direction of the arrow, the lubricating oil 3 enters between the tank bottom surface and the lower surface of the floating ring from the dynamic pressure generating groove 4 along the inclined surface 4a, so that the floating ring 2 rises. In this case, the motor is supported by hydraulic pressure and stably rotates without vibration.

However, in the conventional fluid bearing, the shape and arrangement of the dynamic pressure generating grooves 4 have directionality with respect to rotation, and the floating ring 2 is rotated when the surface plate is rotated forward and reversely.
Because of the difference in the flying height, when this is used in a forward-reverse processing type flat polishing apparatus, there is a problem that the polishing rate is different between the forward rotation processing and the reverse rotation processing, and the polishing accuracy is reduced.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a forward / reverse machining type surface polishing apparatus using a fluid bearing.
An object of the present invention is to improve the polishing accuracy by improving the difference in the characteristics of the fluid bearing when the surface plate is rotated forward and backward.

[0006]

In order to solve the above-mentioned problems, a flat-surface polishing apparatus according to the present invention comprises a platen for polishing a work, which is rotatable in forward and reverse directions, a fluid bearing mechanism for supporting a thrust load of the platen, A drive unit for rotating the surface plate in the forward and reverse directions, wherein the fluid bearing mechanism is housed in an annular oil tank mounted on the body so as to surround a rotation center of the surface plate, and the oil tank. A plurality of lubricating oils having an annular floating ring attached to the surface plate and rotatably fitted to the oil tank, wherein at least one of the bottom surface of the oil tank or the lower surface of the floating ring has an arc shape; Between the sliding members of oil
Attach it in a ring at a small interval to be a flow path.
Hydraulic lifting force is applied to the rotating floating ring on the moving member.
To provide a dynamic pressure generating groove,
A groove shape that forms a symmetrical inclined surface where both groove walls are gently inclined
And a groove pattern symmetrical with respect to the forward / reverse rotation of the floating ring.

According to the planar polishing apparatus of the present invention having the above structure, the formation pattern of the dynamic pressure generating groove in the fluid bearing mechanism has no directionality with respect to rotation. Thus, the floating amount of the floating ring is always constant, and the polishing accuracy is improved.

In one specific embodiment of the present invention,
The dynamic pressure generating groove is provided at the bottom of the oil tank.
At the bottom of the oil tank, the floating ring
Form a part higher than the bottom of the tank corresponding to
The sliding member is mounted on the upper surface of the minute . In the present invention, a pellet surface plate having a large number of polishing pellets adhered to a work surface is used as the surface plate.

[0009]

An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a main part of a double-side polishing apparatus to which the present invention is applied. This polishing apparatus is suspended from a body 10 and a rod 19a of a cylinder 19 attached to the body 10, and is capable of moving up and down. A platen 11, a lower platen 12 facing the upper platen 11, and a plurality of carriers 1
3 and the carrier 13
Is provided with a sun gear 14 and an internal gear 15 for planetary movement of a workpiece, and a workpiece 16 held by each carrier 13 is polished from both sides by rotating upper and lower platens 11, 12. Both the platens 11 and 12 are pellet surface plates in which a large number of polishing pellets are attached to a work surface.

[0010] The two stools 11 and 12 and the two gears 13 and 1
Reference numeral 4 is connected to a drive source (not shown) via a concentric drive shaft, and can be driven at a required rotational speed in both forward and reverse directions. Of these drive shafts, the lower platen drive shaft, the sun gear drive shaft and the internal gear drive shaft are always connected to the lower platen 12, the sun gear 14 and the internal gear 15, respectively, but are located at the center. The upper surface plate drive shaft 11a has a cap-shaped driver 17 at its upper end, and a hook 18 provided on the upper surface plate 11 side when the upper surface plate 11 is lowered from the position shown in FIG. Is engaged with the upper surface plate 11 via the driver 17 by being fitted into the engagement groove 17a on the outer surface of the driver 17, and when the upper surface plate 11 rises to the position of FIG. I'm leaving.

The lower platen 12 is supported by a fluid bearing mechanism 20 for supporting a thrust load. As can be seen from FIGS. 2 and 3, the fluid bearing mechanism 20
An annular oil tank 21 provided on the body 10 so as to surround the rotation center of the lower stool 12, a lubricating oil 22 contained in an appropriate amount in the oil tub 21, and a lower end attached to the lower stool 12 and in the oil tub 21. And an annular floating ring 23 fitted with the ring.

At the bottom of the oil tank 21, a portion 21a corresponding to the floating ring 23 in the middle of the groove width is slightly raised, and a plurality of arc-shaped sliding members are formed on the upper surface of the raised portion 21a. (Tarkite) 24 are annularly mounted at a small interval 25 serving as an oil flow path between each other, and act on the upper surface of each sliding member 24 with a floating force by hydraulic pressure on the rotating floating ring 23. The dynamic pressure generating groove 26 is formed so as to be symmetrical with respect to the forward / reverse rotation of the floating ring 23.

As can be seen from FIG. 4, the dynamic pressure generating groove 26 has a bilaterally symmetric inclined surface 26 that gently inclines both groove walls.
By forming a suitable number of such symmetrical dynamic pressure generating grooves 26 in the circumferential direction and the radial direction, the groove pattern in the normal rotation direction of the floating ring 23 is formed. The groove pattern in the reverse direction is the same.

In the planar polishing apparatus having the above structure, the sun gear 14 and the internal gear 15 are rotated at a required speed in a required direction by the respective drive shafts to cause the carrier 13 to perform planetary motion. The work 1 held by each carrier 13 is rotated while rotating the work 12 in a required direction at a required speed.
6 is polished by being sandwiched between both surface plates 11 and 12 from both sides. Then, when a certain polishing time has elapsed, the above-mentioned gears 14 and 15 and the surface plates 11 and 12 are rotated in the reverse direction to perform the same polishing, and thereafter, such forward and reverse rotation processing is repeated a required number of times.

At this time, in the hydrodynamic bearing mechanism 20, when the floating ring 23 rotates in one direction as shown in FIG. 4, the upper surface of the sliding member 24 moves along the rotation direction inclined surface 26a of the dynamic pressure generating groove 26. Since the lubricating oil 22 enters between the lower ring and the lower surface of the floating ring 23, the floating ring 23 floats by the action of hydraulic pressure, and the lower platen 12 rotates while being supported in a non-contact state by hydraulic pressure. For this reason, the vertical vibration of the lower stool 12 is suppressed, and the lower stool 12 rotates stably without vibration.

Even if the rotation direction of the platen 12 is reversed, the formation pattern of the dynamic pressure generating grooves 26 is the same as in the case of normal rotation, so that the floating amount of the floating ring 23 is the same as in the case of normal rotation. There is no difference in the polishing rate depending on the rotation direction.

In the above embodiment, the dynamic pressure generating groove 26 is
The pattern for forming the dynamic pressure generating groove 26 symmetrically with respect to the forward / reverse rotation of the floating ring 23 is limited to such a pattern. Not done. For example, as shown in FIGS. 5 and 6, the curved dynamic pressure generating grooves 26 may be provided in a pattern symmetrical to each other, or may be another pattern. Further, the groove shape itself of the dynamic pressure generating groove 26 is not necessarily required to be symmetrical, and it is sufficient that at least one groove wall has an inclined surface 26 a capable of generating a dynamic pressure by the lubricating oil 22. May be arranged such that the entire pattern is symmetrical with respect to the forward / reverse rotation of the floating ring 23.

The same effect can be obtained by providing the dynamic pressure generating groove 26 on the bottom surface of the floating ring 23 at the same time as or instead of providing it on the bottom of the oil tank 21 as in the illustrated embodiment. Further, in the above-described embodiment, the double-side polishing apparatus provided with two upper and lower surface plates has been described. However, a single-side polishing device for polishing one surface of the work only with the lower surface plate may be used. Not limited to the pellet surface plate, other materials such as a work surface with a polishing pad attached thereto can also be used.

[0019]

As described above, according to the present invention, the dynamic pressure generating grooves in the hydrodynamic bearing mechanism are arranged symmetrically with respect to the forward / reverse rotation of the floating ring so that the surface plate is rotated forward. The floating amount of the floating ring can always be kept constant between the case of the reverse rotation and the case of the reverse rotation, whereby the polishing accuracy of the work can be enhanced.

[Brief description of the drawings]

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

FIG. 2 is an enlarged sectional view of a hydrodynamic bearing mechanism.

FIG. 3 is a partial plan view of an oil tank in the fluid bearing mechanism.

FIG. 4 is a sectional view of an essential part for explaining the operation of the fluid bearing mechanism.

FIG. 5 is a partial plan view showing a modification of the oil tank in the fluid bearing mechanism.

FIG. 6 is a partial plan view showing another modification of the oil tank in the fluid bearing mechanism.

FIG. 7 is a sectional view of a conventional fluid bearing.

FIG. 8 is a partial plan view of an oil tank in a conventional fluid bearing.

FIG. 9 is a cross-sectional view of a main part for describing the operation of a conventional fluid bearing.

[Explanation of symbols]

 Reference Signs List 10 Airframe 11, 12 Surface plate 16 Workpiece 20 Fluid bearing mechanism 21 Oil tank 22 Lubricating oil 23 Floating ring

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B24B 37/04 F16C 17/04

Claims (3)

(57) [Claims] 1. A platen for polishing a work, which is rotatable forward and backward,
A fluid bearing mechanism for supporting the thrust load of the surface plate; and a drive unit for rotating the surface plate in forward and reverse directions. The fluid bearing mechanism is mounted on the body so as to surround a rotation center of the surface plate. An annular oil tank, a lubricating oil housed in the oil tank, and an annular floating ring attached to the surface plate and rotatably fitted to the oil tank, the bottom surface or the floating surface of the oil tank. At least one of the lower surfaces of the ring is provided with a plurality of arc-shaped sliding members and an oil flow path therebetween.
Attach them in a ring at a small interval, and slide each member.
The hydraulic floating force on the rotating floating ring.
Dynamic pressure generating grooves for the
Is shaped into a groove that forms a symmetrical inclined surface with a gentle slope
And symmetrical with respect to the forward and reverse rotation of the levitating ring.
A flat polishing apparatus using a fluid bearing formed in a groove pattern . 2. The planar polishing apparatus according to claim 1, wherein
The above-mentioned dynamic pressure generating groove is provided at the bottom of the oil tank.
At the bottom of the tank, at the middle of the groove width,
To form a part that is higher than the bottom of the tank.
The sliding member is attached to the upper surface,
What to do. 3. The flat polishing apparatus according to claim 1, wherein the platen is configured to paste a large number of polishing pellets on a work surface.
It is characterized by being a pellet surface plate attached.