Linearly Advancing Polishing Method And Apparatus
Continuous feeding of workpieces to an apparatus and effective use of the space around the apparatus are difficult in rotary abrasive finishing. To solve such problems, the present invention provides a conceptually novel method and apparatus for linear abrasive finishing. A pair of parallel flat surface plates adjacent in parallel move linearly in opposite directions. A workpiece is pressed onto both of the surface plates to apply a couple of forces for rotational movement to the workpiece. The workpiece is subjected to abrasive finishing with abrasive grains by relative movement between the rotation of the workpiece and the linear movement of the pair of surface plates. The workpiece may be held between the pair of parallel flat surface plates and another pair of parallel flat surface plates facing the pair of parallel flat surface plates before one or both surfaces of the workpiece are subjected to the abrasive finishing. Belt polishers passing over a workpiece support may be used instead of the surface plates.
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The present invention relates to abrasive finishing of, for example, metals (steel and nonferrous metals) and nonmetallic materials (ceramic, glass, and plastic).
BACKGROUND ARTAbrasive finishing, which is used as a final finishing step in mechanical processing, is growing in importance as device quality has improved recently. Examples of abrasive finishing include lapping, in which a workpiece is rubbed with a lap using an abrasive containing dispersed loose abrasive grains, and polishing, in which a workpiece is polished with a tool softer than metal, called a polisher.
Abrasive finishing can be performed in various ways, including single-side finishing, double-side finishing, and curved surface finishing.
Abrasive finishing using a rotary abrasive surface plate, however, needs the time for attachment/detachment of workpieces because the finishing is generally a batch process in which the abrasive surface plate must be stopped to detach and attach the workpieces. Also, an automated double-side abrasive finishing system capable of continuous feeding of workpieces to the apparatus is difficult to establish. In particular, improving abrasive finishing efficiency is challenging in mass production.
Furthermore, the rotary abrasive surface plate requires a diameter of at least twice that of a workpiece because the workpiece is processed on the abrasive surface plate. Processing a larger workpiece requires a larger abrasive surface plate and a larger area for installation of the abrasive finishing apparatus. In addition, a rotary abrasive surface plate for double-side abrasive finishing having a horizontal rotating axis and a vertical plane of rotation is difficult to produce because of the mechanical difficulty of supporting a workpiece. This makes it difficult to sufficiently utilize the space around the apparatus. Accordingly, the development of a conceptually novel method for abrasive finishing has strongly been demanded to facilitate establishment of a more compact automated abrasive finishing system capable of continuous feeding of workpieces to an apparatus and to sufficiently utilize the space around the apparatus.
MEANS FOR SOLVING THE PROBLEMSThe present invention provides a conceptually novel method for abrasive finishing which can facilitate establishment of a compact automated abrasive finishing system capable of continuous feeding of workpieces to an apparatus and which allows effective use of the space around the apparatus. Such a system is difficult to establish based on existing methods for rotary abrasive finishing using rotary abrasive surface plates. The present invention also provides an abrasive finishing apparatus based on the novel method.
That is, the present invention provides a method for linear abrasive finishing which includes pressing a workpiece onto both of a pair of parallel flat surface plates that are adjacent in parallel and move linearly in opposite directions to apply a couple of forces for rotational movement to the workpiece; and subjecting the workpiece to abrasive finishing with abrasive grains by relative movement between the rotation of the workpiece and the linear movement of the pair of flat surface plates. In this method, the workpiece may be held between the pair of parallel flat surface plates and another pair of parallel flat surface plates facing the pair of parallel flat surface plates before one or both surfaces of the workpiece are subjected to the abrasive finishing.
The present invention further provides a method for linear abrasive finishing which includes pressing a workpiece onto a flat surface plate that moves linearly to apply a couple of forces for rotational movement to the workpiece; and subjecting the workpiece to abrasive finishing with abrasive grains by relative movement between the rotation of the workpiece and the linear movement of the flat surface plate. The flat surface plate has a surface whose friction coefficient differs in a direction perpendicular to a direction in which the flat surface plate moves linearly. In this method, the workpiece may be held between the flat surface plate and another flat surface plate facing the flat surface plate before one or both surfaces of the workpiece are subjected to the abrasive finishing.
In the above methods, the abrasive finishing can be continuously performed by gradually moving an elongated plate-like carrier having a circular hole holding a circular subcarrier holding the workpiece in one direction as the abrasive finishing progresses.
In the above methods, additionally, belt polishers passing over a workpiece support may be used instead of the flat surface plates.
The present invention further provides a linear abrasive finishing apparatus including a pair of parallel flat surface plates adjacent in parallel; means for linearly moving the flat surface plates in opposite directions; and means for pressing a workpiece onto the flat surface plates. This apparatus may further include another pair of parallel flat surface plates disposed opposite the pair of parallel flat surface plates such that the workpiece is held therebetween.
The above apparatus may further include an elongated plate-like carrier for continuously feeding the workpiece to the abrasive finishing apparatus and ejecting the workpiece therefrom during the abrasive finishing. This apparatus may further include a circular workpiece-holding subcarrier hole in the plate-like carrier, and the center of rotation of the hole may be located on or away from an adjacent center line between the parallel flat surface plates. In addition, the circular subcarrier hole in the plate-like carrier may include a workpiece-holding hole having a shape such as a circle, a square, a rectangle, or a polygon, and the center of rotation thereof may be located on the adjacent center line between the parallel flat surface plates.
The present invention further provides a linear abrasive finishing apparatus including a flat surface plate that moves linearly and has a surface whose friction coefficient differs in a direction perpendicular to a direction in which the flat surface plate moves linearly; and means for pressing a workpiece onto the flat surface plate. This apparatus may further include another flat surface plate disposed opposite the flat surface plate such that the workpiece is held therebetween.
Each of the above apparatuses may include a workpiece support and a pair of belt polishers passing over the workpiece support instead of the flat surface plates.
The methods according to the present invention leave no unidirectional abrasive streaks because the abrasive finishing is performed by rotating a workpiece using a couple of forces produced by the linear movement of the flat surface plates. These methods can therefore provide an excellent nondirectional finished surface with a roughness of about 1.5 nm or less (intervals of several atoms or less). Without rotation, the workpiece would suffer streaks oriented in the direction in which the flat surface plates move, leading to a roughness exceeding 10 nm. The methods according to the present invention can thus provide an ultrasmooth surface without such abrasive streaks.
ADVANTAGESThe methods for linear abrasive finishing according to the present invention have the following advantages:
1) An abrasive finishing apparatus that is more space-saving than rotary abrasive finishing apparatuses can be produced.
2) An automated abrasive finishing system capable of continuous feeding of workpieces to the apparatus can be established. Such a system is difficult to establish based on known methods for abrasive finishing using rotary abrasive surface plates.
3) An automated vertical double-side abrasive finishing system with a vertical plane of rotation can be produced to effectively utilize the space around the apparatus.
BEST MODE FOR CARRYING OUT THE INVENTION The mechanism of a method for linear abrasive finishing according to the present invention will now be described with reference to
In the method according to the present invention, the rotation of a workpiece depends basically on the movement direction and surface structure of plates or polishers. The workpiece may also be rotated using a driving force generated by, for example, a motor to control the relative movement between the workpiece and the plates or polishers for abrasive finishing. An abrasive finishing apparatus based on the method can perform abrasive finishing if the total width of the pair of polishers 11 is slightly larger than the diameter of the workpiece 3. The pair of polishers 11 thus occupy a smaller space than a rotary abrasive surface plate.
For double-side polishing using this method, as shown in
Referring to
The method for abrasive finishing shown in FIGS. 1 to 3 can be used for workpieces having a central hole, such as magnetic disc substrates, if the workpiece-holding hole of the carrier 13 is disposed on the adjacent center line between the pair of parallel flat surface plates. For workpieces having no central hole, such as silicon wafers, however, the central portions thereof cannot be subjected to abrasive finishing because these portions do not come into contact with the polishers. Referring to
The hole of the subcarrier 13A may be formed in another shape such as a square, a rectangle, or a polygon to perform abrasive finishing. For abrasive finishing of a circular workpiece having no hole, the center of the workpiece hole in the carrier 13 may be located away from the adjacent center line to allow abrasive finishing of the entire surfaces of the workpiece 3 without using the subcarrier 13A.
Referring to
These abrasive finishing methods can be used for single-side or double-side polishing. Referring to
Each polisher has different surface conditions on both sides of a longitudinal center line to produce different frictional forces. For example, the surface of the polisher may have circular holes or linear grooves on either side of the longitudinal center line to reduce the contact area between the polisher and the workpiece on the side. As a result, a smaller frictional force can be produced than on the other side. Different frictional forces can also be produced on both sides of the longitudinal center line to apply a couple of forces by changing the mechanical properties of the polisher, such as surface hardness, to create different contact conditions between the workpiece and the polisher on both sides.
A couple of forces for rotational movement is thus applied to the workpiece 3. An abrasive liquid containing loose abrasive grains is supplied to the surfaces of the polishers 11. Relative movement between the rotation of the workpiece 3 and the linear movement of the polishers 11 causes the loose abrasive grains to remove top and bottom surface portions of the workpiece 3, thus forming highly smooth surfaces. In this method, as shown in
A workpiece is held between linearly moving flat surface plates facing each other to perform single-side or double-side abrasive finishing in the embodiments shown in
An example of a method according to the present invention will be described below with reference to
In
-
- 3 workpiece
- 10 surface plate
- 11 polisher
- 12 loose abrasive grains
- 13 carrier
- 14 holder
- 15 abrasive liquid
Claims
1. A method for linear abrasive finishing, comprising pressing a workpiece onto both of a pair of parallel flat surface plates that are adjacent in parallel and move linearly in opposite directions to apply a couple of forces for rotational movement to the workpiece; and subjecting the workpiece to abrasive finishing with abrasive grains by relative movement between the rotation of the workpiece and the linear movement of the pair of flat surface plates.
2. The method for linear abrasive finishing according to claim 1, wherein the workpiece is held between the pair of parallel flat surface plates and another pair of parallel flat surface plates facing the pair of parallel flat surface plates before one or both surfaces of the workpiece are subjected to the abrasive finishing.
3. A method for linear abrasive finishing, comprising pressing a workpiece onto a flat surface plate that moves linearly to apply a couple of forces for rotational movement to the workpiece, the flat surface plate having a surface whose friction coefficient differs in a direction perpendicular to a direction in which the flat surface plate moves linearly; and subjecting the workpiece to abrasive finishing with abrasive grains by relative movement between the rotation of the workpiece and the linear movement of the flat surface plate.
4. The method for linear abrasive finishing according to claim 3, wherein the workpiece is held between the flat surface plate and another flat surface plate facing the flat surface plate before one or both surfaces of the workpiece are subjected to the abrasive finishing.
5. The method for linear abrasive finishing according to claim 1, wherein the abrasive finishing is continuously performed by gradually moving an elongated plate-like carrier having a circular hole holding a circular subcarrier holding the workpiece in one direction as the abrasive finishing progresses.
6. The method for linear abrasive finishing according to claim 1, wherein belt polishers passing over a workpiece support are used instead of the flat surface plates.
7. A linear abrasive finishing apparatus comprising a pair of parallel flat surface plates adjacent in parallel; means for linearly moving the flat surface plates in opposite directions; and means for pressing a workpiece onto the flat surface plates.
8. The linear abrasive finishing apparatus according to claim 7, further comprising another pair of parallel flat surface plates disposed opposite the pair of parallel flat surface plates such that the workpiece is held therebetween.
9. The linear abrasive finishing apparatus according to claim 8, further comprising an elongated plate-like carrier for continuously feeding the workpiece to the abrasive finishing apparatus and ejecting the workpiece therefrom during the abrasive finishing.
10. The linear abrasive finishing apparatus according to claim 9, further comprising a circular workpiece-holding subcarrier hole in the plate-like carrier, the center of rotation of the hole being located on or away from an adjacent center line between the parallel flat surface plates.
11. The linear abrasive finishing apparatus according to claim 10, wherein the circular subcarrier hole in the plate-like carrier includes a workpiece-holding hole having a shape such as a circle, a square, a rectangle, or a polygon, the center of rotation thereof being located on the adjacent center line between the parallel flat surface plates.
12. A linear abrasive finishing apparatus comprising a flat surface plate that moves linearly and has a surface whose friction coefficient differs in a direction perpendicular to a direction in which the flat surface plate moves linearly; and means for pressing a workpiece onto the flat surface plate.
13. The linear abrasive finishing apparatus according to claim 12, further comprising another flat surface plate disposed opposite the flat surface plate such that the workpiece is held therebetween.
14. The linear abrasive finishing apparatus according to claim 7, comprising a workpiece support and a pair of belt polishers passing over the workpiece support instead of the flat surface plates.
Type: Application
Filed: Mar 29, 2005
Publication Date: Aug 30, 2007
Applicant: JAPAN SCIENCE AND TECHNOLOGY AGENCY (Kawaguchi-shi)
Inventor: Heiji Yasui (Kumamoto)
Application Number: 10/599,562
International Classification: B24B 1/00 (20060101); B24B 5/00 (20060101);