Method for polishing slight area of surface of workpiece and tool therefor

• US 5,404,680 A
• Filed: 03/16/1994
• Issued: 04/11/1995
• Est. Priority Date: 05/09/1991
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kato, Koji, Umehara, Noritsugu, Mizuguchi, Shinichi
• Primary Examiner(s): Lavinder, Jack W.
• Application Number:
  US08/213,812
• Time in Patent Office: 391 Days
• Field of Search: 51/59 SS, 51/165 R, 51/165.71, 51/165.75, 51/165.76, 51/165.77, 51/281 R, 51/317, 51/318, 51/7, 51/57, 51/58
• US Class Current: 451/36
• CPC Class Codes: B23Q 1/34 Relative movement obtained by use of deformable elements, e.g. piezoelectric, magnetostrictive, elastic or thermally-dilatable elements sensitive elements capable of producing movement or displacement for purposes not limited to measurement G12B1/00
• CPC Class Codes: B24B 1/005 using a magnetic polishing agent
• CPC Class Codes: B24B 1/04 subjecting the grinding or polishing tools, the abrading or polishing medium or work to vibration, e.g. grinding with ultrasonic frequency polishing or abrading surfaces on work by means of tumbling apparatus B24B31/00, involving oscillating or vibrating containers B24B31/06; superfinishing surfaces on work, e.g. by means of abrading blocks reciprocating with high frequency, B24B35/00
• CPC Class Codes: B24B 13/00 Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor edging optical work, e.g. lenses, prisms B24B9/14
• CPC Class Codes: B24B 35/00 Machines or devices designed for superfinishing surfaces on work, i.e. by means of abrading blocks reciprocating with high frequency

Abstract

A method for polishing a slight region of the surface of a workpiece utilizes an actuator or actuators having piezoelectric elements. The actuators cause slight movement of a polishing portion disposed at the leading end of a polishing tool in an XY-direction parallel with the surface of the workpiece and/or a Z-direction perpendicular to the surface of the workpiece. A polishing material, including a magnetic fluid and nonmagnetic abrasive grains dispersed in the magnetic fluid, is held magnetically in a space between the polishing portion and the workpiece.

Claims

1. A method for polishing a slight region of a surface of a workpiece, comprising the steps of:

applying a magnetic field, in a Z-direction perpendicular to the surface of the workpiece, to a space between a polishing portion disposed at a leading end of a polishing tool and the workpiece to magnetically hold a polishing material in the space between the polishing portion and the workpiece, the polishing material including magnetic fluid and nonmagnetic abrasive grains disposed in the magnetic fluid;

applying pressure mechanically in the space between the surface of the workpiece and the polishing portion;

operating an actuator or actuators, each actuator comprising a piezoelectric element, to cause the polishing portion disposed at the leading end of the polishing tool to undergo a slight movement in at least one of an XY-direction parallel with the surface of the workpiece and the Z-direction to polish the slight region of the surface of the workpiece with the polishing material; and

stepwise reducing an amount of abrasion per period of time by stepwise decreasing a frequency of the slight movement of the polishing portion while the workpiece is being polished.

2. A method for polishing a slight region of a surface of a workpiece, comprising the steps of:

applying a magnetic field, in a Z-direction perpendicular to the surface of the workpiece, to a space between a polishing portion disposed at a leading end of a polishing tool and the workpiece to magnetically hold a polishing material in the space between the polishing portion and the workpiece, the polishing material including magnetic fluid and nonmagnetic abrasive grains disposed in the magnetic fluid;

applying pressure mechanically in the space between the surface of the workpiece and the polishing portion;

operating an actuator or actuators, each actuator comprising a piezoelectric element, to cause the polishing portion disposed at the leading end of the polishing tool to undergo a slight movement in at least one of an XY-direction parallel with the surface of the workpiece and the Z-direction to polish the slight region of the surface of the workpiece with the polishing material;

stepwise reducing an amount of abrasion per period of time by stepwise decreasing a frequency of the slight movement of the polishing portion while the workpiece is being polished;

moving the polishing portion away from the surface of the workpiece for a short period of time to let nonmagnetic abrasive grains flow in the space between the surface of the workpiece and the polishing portion; and

wherein the leading end of the polishing portion comprises a rotatable sphere.