JPH10545A - Polishing head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect polishing load by providing a linear guide which guides a load detector connected to a rotary shaft which is supported by a fluid bearing and has a motor via a fluid coupling, in the rotary shaft direction, and a pressurizer which imparts load on the rotary shaft via the load detector. SOLUTION: A rotary shaft 89 having a polishing tool 87 installed therein is provided with pneumatic bearings 93, 95 supporting its top and bottom, the rotor 107 of a motor 105 fixed to its center, and a stator arranged around the circumference. A load detector 117 is connected to a fluid coupling 119 arranged in the top of the rotary shaft 89 and guided by a linear guide 121 so as to move freely in the vertical direction. A load controller 85 which is arranged on the top of a casing 115 is provided with a pressurizer 123, fixed to the casing 115 via a housing 125, and connected to the load detector 117. A controller 111 inputs load signals from the load detector 117 and rotation signals of the rotary shaft 89 from a rotation detector 113, and controls the rotary speed of a control valve 127 and a motor 105 based on these signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polishing head used in a polishing apparatus.

[0002]

2. Description of the Related Art Recently, optical components such as lenses and mirrors have been
Higher accuracy is required. In particular, an optical component used in a measuring device or an exposure device that uses a short wavelength such as ultraviolet light or soft X-ray as a light source is required to have a shape accuracy of 1 nm.

Therefore, in polishing, it is important not only to smooth the surface but also to obtain an accurate polishing removal amount in order to finish the surface shape with high precision. Generally, it is known that the removal amount of polishing is proportional to the contact pressure between the polishing head attached to the polishing apparatus and the processing surface, the relative movement speed, and the processing time. Therefore, in order to perform highly accurate polishing, it is necessary to precisely control the swinging and rotating motion of the polishing head and the polishing load.

[0004] Particularly, in the finishing stage, since the amount of polishing removal is very small, it is necessary to control a low load with high precision. Generally, the swinging of the polishing head is performed by the polishing apparatus, and the rotation and the control of the polishing load are performed by the polishing head. FIG. 3 shows a conventional polishing head.
The load detection unit 13 and the load control unit 15 form a main part.

The polishing shaft 11 includes a polishing tool 17 and a rotating shaft 1.
9, bearings 21, 23, motor 25, rotation detector 27, linear guide 29, and housings 31, 33, 35. The load detection unit 13 includes a joint 37, a load detector 39, a table 41, a linear guide 43, and a housing 45.

The load controller 15 includes a pressurizer 47 and a control valve 4
9 and a housing 51. The polishing shaft 11, the load detector 13, and the load controller 15 are attached to the housings 53 and 55 to form a polishing head, which is controlled by the controller 57. Polishing of a workpiece using such a polishing head is performed as described below.

First, a polishing head is positioned directly above a processing position by a moving means (not shown) of the polishing apparatus. next,
The moving means lowers the polishing head until just before the polishing head comes into contact with the workpiece.

Thereafter, the polishing shaft 11 is pushed down by the pressurizer 47 until the load detector 39 indicates a predetermined value.
A polishing tool 17 is pressed against the workpiece. Then, the pressing of the polishing shaft 11 is stopped at a position where the load detector 39 indicates a predetermined value, and the rotation of the rotating shaft 19 is
Then, the polishing tool 17 is rotated to start polishing.

In order to obtain a necessary polishing removal amount, an appropriate processing time for a polishing load is previously calculated, and the polishing is performed only for this time. However, in the above-described polishing head, since the value indicated by the load detector 39 includes the frictional force generated in the movable parts such as the bearings 21 and 23 of the polishing shaft 11 and the linear guide 29, the load detector 39 is The indicated value is different from the value indicating the actual polishing load at the tip of the polishing tool 17, and a problem arises that the required removal amount cannot be obtained with the processing time obtained by calculation.

Therefore, in the polishing process in such a low load region, it is important to keep the frictional force generated in the movable portion of the polishing shaft 11 low. Conventionally, as a polishing head capable of holding down a frictional force generated in a movable portion of a polishing shaft portion, for example, Japanese Patent Laid-Open No. 63-232929
The one disclosed in Japanese Patent Application Publication No. JP-A-2006-26095 is known.

FIG. 4 shows a polishing head disclosed in this publication. In this polishing head, a rotating shaft 59 is rotatably supported by a fluid bearing 61 in a non-contact manner. Further, the rotor 65 of the motor 63 is fixed to the rotating shaft 59,
By disposing the stator 67 around the rotating shaft 59
Are rotatable in a non-contact manner. Further, the rotation shaft 59
Is performed using the fluid pressure from the air inlets 69 and 71, and the polishing shaft 59 can be moved in a state where the frictional force is kept low.

[0012]

However, in the conventional polishing head, there is a problem in the structure of the joint 37 connecting the polishing shaft 11 and the load detector 39, and a frictional force and a moment are generated in the joint 37. There is a problem that an accurate polishing load cannot be detected. 5 and 6 show a conventional joint 37, which has a gimbal structure.

That is, the polishing shaft 11 and the load detector 39
The ball bearings 73 and 75 are used to transmit the vertical movement of the polishing shaft 11 so as to absorb the tilt error generated in the fastening with the shaft. It is difficult to detect an accurate polishing load due to generation of frictional force and moment. The present invention has been made to solve such a conventional problem, and has as its object to provide a polishing head that can accurately detect a polishing load.

[0014]

According to a first aspect of the present invention, there is provided a polishing head comprising: a rotary shaft having a polishing tool fixed to one end; a fluid bearing for supporting the rotary shaft so as to be movable in the axial direction; A motor having a fixed rotor and a stator disposed around the rotor in a non-contact manner, and a load detector connected to the rotating shaft via a fluid coupling attached to the other end of the rotating shaft; A linear guide for guiding the load detector in the axial direction of the rotary shaft, and a pressurizer for applying a load to the rotary shaft via the load detector are provided.

According to a second aspect of the present invention, in the polishing head according to the first aspect, the fluid used for the fluid coupling is air. According to a third aspect of the present invention, in the polishing head according to the second aspect, in the fluid coupling, a disk member to which the other end of the rotary shaft is connected is rotatably disposed in an air chamber formed in the coupling body. In addition, a load detector is connected to a side of the joint body opposite to the rotating shaft, and an air supply pipe is connected to the air chamber.

(Operation) In the polishing head according to the first aspect, when the motor including the rotor fixed to the rotating shaft and the stator arranged around the rotor in a non-contact manner is driven, the rotating shaft supported by the fluid bearing is driven. The polishing tool is rotated. On the other hand, when the pressurizer is operated, the load detector is guided by the linear guide and moves in the axial direction of the rotating shaft, and the rotating shaft connected to the load detector via the fluid coupling is moved in the axial direction. .

In the polishing head according to the second aspect, air is used as the fluid of the fluid coupling. In the polishing head according to the third aspect, the disk member to which the rotating shaft is fixed is rotatable in a state of being floated by the pressurized air from the air supply pipe in the air chamber formed in the joint body to which the load detector is connected. Supported,
The load detector and the rotating shaft are connected.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an embodiment of a polishing head according to the present invention. The main portion of the polishing head includes a polishing shaft 81, a load detector 83, and a load controller 85. The polishing shaft 81 has a rotating shaft 89 at the tip of which a polishing tool 87 is mounted. This rotating shaft 89 is
It is arranged so as to penetrate the center of the housing 91, and is supported vertically by air bearings 93 and 95.

The air bearings 93 and 95 have an air supply source 97.
Are connected via the filter 99 and the pipes 101 and 103. A rotor 107 of the motor 105 is fixed at the center of the rotating shaft 89, and a stator 109 is arranged around the rotor 107. The motor 105 is a brushless motor in which a rotor 107 is made of a permanent magnet and a stator 109 is made of an electromagnet.
1 constitutes an AC servomotor.

The range of the number of rotations of the motor 105 is 10 to 100 rpm. A rotation detector 113 composed of a photoelectric rotary encoder is provided above the rotation shaft 89.
Is arranged. The load detection unit 83 has a load detector 117 that is disposed in the housing 115 and that is composed of a load cell.

The load detector 117 is connected to a fluid coupling 119 disposed at the upper end of the rotating shaft 89. The load detector 117 is movably guided in a vertical direction by a linear guide 121 composed of a cross roller guide. The load control unit 85 is disposed at an upper part of the housing 115,
It has a pressurizer 123 consisting of a pneumatic cylinder.

The pressurizer 123 is fixed to the housing 115 via the housing 125, and the piston rod 123a is connected to the load detector 117. In the pressurizer 123,
The air supply source 97 is provided with a control valve 127 and a pipe 129,1.
31 are connected. Although the air pressure supplied to the control valve 127 is 4 kgf / cm ² , air controlled to a required pressure by the control valve 127 is supplied to the pressurizer 123 formed of a pneumatic cylinder.

In FIG. 1, reference numeral 111 denotes a controller. The controller 111 inputs a load signal from the load detector 117 and a rotation signal of the rotating shaft 89 from the rotation detector 113. And, based on these signals,
The number of rotations of the control valve 127 and the motor 105 is controlled.

FIG. 2 is a sectional view showing details of the fluid coupling 119 of FIG. The fluid coupling 119 has an annular air chamber 135 in a coupling body 133 made of, for example, a stainless metal. The outer periphery of the disk member 137 is accommodated in the air chamber 135, and the upper end of the rotating shaft 89 is connected to the center of the disk member 137.

The shaft 117a of the load detector 117 is connected to the joint body 133 on the side opposite to the rotating shaft 89. In the air chamber 135, air supply pipes 139 and 141 are opened from above and below, for example, 4 kgf / cm ^2.
Of compressed air is supplied. The minimum gap between the disk member 137 and the air chamber 135 is, for example, 10 × 10 ⁻⁶ m, and no sealing is performed.

Therefore, the compressed air is released to the atmosphere from the gap, but the air supply is always larger, so that the air chamber is always kept at a constant pressure. In addition, since the disk member 137 rotates at a low speed, the influence of air vortex or the like can be ignored. In such a fluid coupling 119, inaccuracy in load transmission due to an error in the mounting position between the shaft portion 117a of the load detector 117 and the center of the disk member 137 is extremely small.

In the above-described polishing head, when the motor 105 including the rotor 107 fixed to the rotating shaft 89 and the stator 109 arranged around the rotor 107 in a non-contact manner is driven, the polishing head is supported by the air bearings 93 and 95. Rotating shaft 89
Is rotated, and the polishing tool 87 is rotated. On the other hand, when the pressurizer 123 is operated, the load detector 117 is guided by the linear guide 121 and moves in the axial direction of the rotary shaft 89. It is moved in the axial direction.

The polishing of the workpiece using the above-described polishing head is performed as described below. First, the polishing head is positioned directly above the processing position by a moving unit (not shown) of the polishing apparatus. Next, the polishing head is lowered by the moving means until just before the polishing head comes into contact with the workpiece.

Thereafter, the rotating shaft 89 is pushed down by the pressurizer 123 until the load detector 117 indicates a predetermined value, and the polishing tool 87 is pressed against the workpiece. And
At a position where the load detector 117 indicates a predetermined value, the rotating shaft 89
Is stopped, the rotating shaft 89 and the polishing tool 87 are rotated by the driving of the motor 105, and polishing is started.

In order to obtain a necessary polishing removal amount, an appropriate processing time with respect to a polishing load is calculated in advance, and the polishing is performed for this time. In the polishing head configured as described above, since the rotating shaft 89 and the load detector 117 are connected by the fluid coupling 119, it is possible to easily suppress the generation of frictional force and moment at the coupling portion. In addition, the polishing load can be accurately detected.

Therefore, a highly accurate polishing can be performed. In the polishing head described above, the fluid coupling 119 is used.
Since air is used as the fluid, the generation of frictional force and moment can be suppressed lower than when oil or the like is used. Further, in the polishing head described above, the air chamber 135 formed in the joint body 133 is provided.
The disk member 137 is rotatably supported in a state of being floated by the pressurized air in the fluid coupling 119.
Can be simplified.

In the above embodiment, the pressurizer 12
Although an example in which a pneumatic cylinder is used for 3 has been described, the present invention is not limited to such an embodiment, as long as the value of the load detector 117 can be returned to the controller 111 to control the low load. Alternatively, a fluid pressure cylinder using pressure of oil or the like, an electrostrictive element that generates driving force by electricity, a voice coil motor, or the like may be used.

It is desirable that the pressurizer 123 has a controllable load range of 1 × 10 ^-2 to 1 kgf and a load accuracy within ± 5% of the set load.

[0035]

As described above, in the polishing head according to the first aspect, since the rotating shaft and the load detector are connected by the fluid coupling, it is easy to suppress the generation of frictional force and moment at the coupling portion. Thus, the polishing load can be accurately detected.

Therefore, polishing with higher precision can be performed. In the polishing head according to the second aspect, since air is used for the fluid of the fluid coupling, the generation of frictional force and moment can be suppressed lower than in the case where oil or the like is used. In the polishing head according to the third aspect, the disk member is rotatably supported in a state of being floated by the pressurized air in the air chamber formed in the joint body, so that the structure of the fluid coupling can be simplified. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a polishing head of the present invention.

FIG. 2 is a sectional view showing the fluid coupling of FIG. 1;

FIG. 3 is a sectional view showing an example of a conventional polishing head.

FIG. 4 is a sectional view showing another example of a conventional polishing head.

FIG. 5 is a longitudinal sectional view showing the joint of FIG. 3;

FIG. 6 is a transverse sectional view showing the joint of FIG. 5;

[Explanation of symbols]

 87 Polishing tool 89 Rotary shaft 93,95 Air bearing 105 Motor 107 Rotor 109 Stator 113 Rotation detector 117 Load detector 119 Fluid coupling 121 Linear guide 123 Pressurizer 133 Joint body 135 Air chamber 137 Disk member

Claims (3)

[Claims] A rotating shaft to which a polishing tool is fixed at one end; a fluid bearing for supporting the rotating shaft so as to be movable in an axial direction; a rotor fixed to the rotating shaft and non-contact around the rotor A motor having a stator arranged in the following manner; a load detector connected to the rotary shaft via a fluid coupling attached to the other end of the rotary shaft; And a pressurizer for applying a load to the rotating shaft via the load detector. 2. The polishing head according to claim 1, wherein the fluid used for the fluid coupling is air. 3. The polishing head according to claim 2, wherein, in the fluid coupling, a disk member to which the other end of the rotating shaft is connected is rotatably disposed in an air chamber formed in a coupling main body. A polishing head, wherein a load detector is connected to a side of the joint body opposite to the rotating shaft, and an air supply pipe is connected to the air chamber.