System for magnetorheological finishing of substrates

• US 6,506,102 B2
• Filed: 02/01/2001
• Issued: 01/14/2003
• Est. Priority Date: 02/01/2001
• Status: Expired due to Term

• Current Assignee: QED Technologies International, Inc. (Entegris Incorporated)
• Original Assignee: QED Technologies, Inc.
• Inventors: Kordonski, William, Hogan, Stephen, Carapella, Jerry, Price, Andrew S.
• Primary Examiner(s): Nguyen, George
• Assistant Examiner(s): NGUYEN, DUNG V
• Application Number:
  US09/775,282
• Publication Number:
  US 20020102928A1
• Time in Patent Office: 712 Days
• Field of Search: 451/64, 451/36, 451/60, 451/87, 451/93
• US Class Current: 451/64
• CPC Class Codes: B24B 1/005 using a magnetic polishing agent
• CPC Class Codes: B24B 31/112 using magnetically consolidated grinding powder, moved relatively to the workpiece under the influence of pressure

Abstract

An improved system for magnetorheological finishing of a substrate comprising a vertically oriented bowl-shaped carrier wheel having a horizontal axis. The carrier wheel is preferably an equatorial section of a sphere, such that the carrier surface is spherical. The wheel includes a radial circular plate connected to rotary drive means and supporting the spherical surface which extends laterally from the plate. An electromagnet having planar north and south pole pieces is disposed within the wheel, within the envelope of the sphere and preferably within the envelope of the spherical section defined by the wheel. The magnets extend over a central wheel angle of about 120° such that magnetorheological fluid is maintained in a partially stiffened state ahead of and beyond the work zone. A magnetic scraper removes the MRF from the wheel as the stiffening is relaxed and returns it to a conventional fluid delivery system for conditioning and re-extrusion onto the wheel. The system is useful in finishing large concave substrates, which must extend beyond the edges of the wheel, as well as for finishing very large substrates in a work zone at the bottom dead center position of the wheel.

Claims

1. A system for magnetorheological finishing of substrates, comprising:

a) a frame;

b) a carrier wheel rotatably mounted on said frame, said wheel having a hollow interior, the outer surface of said wheel defining a carrier surface for magnetorheological fluid in a work zone, said carrier wheel being an equatorial section of a sphere;

c) a magnet system mounted on said frame for stiffening said magnetorheological fluid on said carrier surface, said magnet system being disposed within the projected envelope of said sphere and including

an electromagnet having windings about a core;

first and second yoke pieces attached to opposite ends of said core and extending substantially parallel into proximity with an inner wall of said carrier surface; and

first and second pole pieces attached respectively to and between said first and second yoke pieces and extending toward each other to define a magnetic gap therebetween adjacent said inner wall for creating a magnetic field in a work zone on said carrier surface.

2. A system in accordance with claim 1 wherein said first and second yoke pieces extend over a central angle of said carrier wheel of about 120°

.

3. A system in accordance with claim 1 wherein said work zone is present on said carrier surface at about a top dead center position of said carrier wheel.

4. A system in accordance with claim 1 wherein said work zone is present on said carrier surface at about a bottom dead center position of said carrier wheel.