Grinding wheel for grinding the flat surface of a hard and brittle material

• US 4,567,694 A
• Filed: 12/05/1983
• Issued: 02/04/1986
• Est. Priority Date: 02/01/1980
• Status: Expired due to Fees

• Current Assignee: Disco Corporation
• Original Assignee: Disco Corporation
• Inventors: Ono, Takatoshi, Sekiya, Shinji
• Primary Examiner(s): Schmidt, Frederick R.
• Assistant Examiner(s): Rose, Robert A.
• Application Number:
  US06/558,266
• Time in Patent Office: 792 Days
• Field of Search: 51/206 R, 51/206 P, 51/209 R, 51/209 DL, 51/206.4, 51/359, 51/379, 51/382, 51/266
• US Class Current: 451/548
• CPC Class Codes: B24D 7/02 Wheels in one piece
• CPC Class Codes: B24D 7/06 with inserted abrasive blocks, e.g. segmental

Abstract

Grinding of flat plates is performed by using a very thin, conical grinding wheel which is attached to the open end of a revolving cup and which projects outwardly from and is inclined with respect to the cup. The peripheral cutting edge of the grinding wheel revolving at high speed is brought into contact with the work. As the grinding wheel is fed, the work is cut by the grinding wheel across its thickness and an undercut part of the work disrupts (i.e. breaks off) by itself to a desired thickness. Thick grinding is also possible if a multiplicity of the grinding wheels are placed one over another at proper intervals.

Claims

1. In combination;

a hard and brittle material workpiece and a grinding wheel for undercutting and disrupting the part of said hard and brittle material workpiece to be removed and simultaneously grinding the workpiece surface revealed by the undercutting, said grinding wheel comprising a cup rotatable about an axis substantially perpendicular to the flat surface to be ground and at least one annular grindstone attached to the open end of said cup for rotation therewith, said grindstone having a means for undercutting and therewith disrupting the part to be removed of a hard and brittle material workpiece and simultaneously grinding the workpiece surface revealed by the undercutting, said means being a thin grinding portion of said grindstone, said grinding portion protruding radially outwardly away in a separate manner from the open end of said cup with inclination relative to said axis and having a means for rigidifying of said grinding portion, said means comprising a circumferentially repeating wavy cross-sectional profile as seen looking edgewise of said grinding portion from its outer peripheral edge along said inclination toward said axis such that said grinding portion appears as a series of circumferentially repeated ridges and valleys radiating from said cup at said inclination, said grinding wheel being adapted to be positioned so that the outer peripheral edge of said grinding portion can interfere with the flat surface to be ground, with the hard and brittle material workpiece and said grinding wheel being moved relative to each other in a direction substantially parallel to the flat surface to be ground whereby the flat surface is ground in a cutting manner, said grindstone being a self-supporting thin shell of electrodeposited upper abrasive material adapted for grinding of silicon workpieces, said shell having thin radially inner and outer peripheral edges defining the thickness of the shell and connected by substantially wider interior and exterior width surfaces extending along said inclination, said shell consisting of a radially inner part fixed at one of said substantially wider width surfaces to said cup and a radially outer part cantilevering outward from said cup and being said grinding portion of said grindstone, said grinding portion having a thickness in the range of only about 0.1 mm to 0.5 mm and a width along said inclination from said cup outward to its peripheral edge about an order of magnitude greater than at least the smaller end of said range, said thickness being substantially constant along said inclination, whereby to minimize surface area of grinding contact with the workpiece and thereby minimize dulling of the grinding portion and consequent frictional heating and structural degradation of the workpiece.

2. The grinding wheel of claim 1 including circumferentially spaced blind slots extending from said outer peripheral edge partway into said grindstone.

3. A grinding wheel for grinding a flat surface of a hard and brittle material comprising a cup and at least one grindstone provided at an open end of said cup, said grindstone having an annular grinding portion which protrudes radially outwardly from the open end of said cup with inclination relative to the central axis of said cup, a substantial fraction of the width of said grindstone being cantilevered out from said cup, such that the radially inner and outer portions of the width of said grindstone are respectively backed by and free of backing by said cup, said grindstone being of electrodeposited super hard abrasive grains with at least said radially outer portion of the width of said grindstone not including any substrate or other backing, said grinding portion having a wavy form as seen looking edgewise thereat, the thickness of said grinding portion being in the range of 0.1 to about 0.5 mm, whereby said grinding portion is sufficiently thin to grind the flat surface in a cutting manner efficiently and accurately.

4. The grinding wheel of claim 3 wherein said grinding portion is corrugated, the corrugations providing said wavy forms, said corrugations being arranged side-by-side circumferentially of the grinding portion having peaks and troughs whose lengths radiate away from the open end of the cup.

5. The grinding wheel of claim 4 wherein the cross-sectional form of said corrugations is a sharp triangular form.

6. The grinding wheel of claim 4 wherein the cross-sectional form of said corrugations is a sinusoidal form.

7. The grinding wheel of claim 3 wherein said super hard abrasive grains are diamond abrasive grains.

8. The grinding wheel of claim 3 wherein the angle (θ

) between said grinding portion and said central axis is at least 100°

.

9. The grinding wheel of claim 3 wherein the hard and brittle material is silicon.

10. A grinding wheel for grinding the flat surface of a hard and brittle material, comprising:

a cup rotatable about an axis substantially perpendicular to the flat surface to be ground and having a downward facing open end; and

an annular grindstone, said grindstone being a thin open-center conical skirt of thickness in the range of about 0.1 to about 0.5 mm, said grindstone protruding downwardly and radially outwardly away from the open end of said cup at an inclination to said axis, the downward facing open end of said cup having an annular surface shaped in conformance to the radially inner part of the width of said grindstone and to which only the radially inner part of the width surface of the grindstone is affixed to fixedly depend the grindstone from the open end of the cup, the thickness of the grindstone being substantially less than its width along its inclination and than its circumference, at least a substantial portion of the inclined width of said grindstone being cantilevered out from said cup, such that the radially inner and outer portions of the width of grindstone are respectively backed by and free of backing by said cup, said grinding wheel being positioned so that the outer peripheral edge of said grindstone interferes with the flat surface to be ground, the hard and brittle material and said grinding wheel being adapted to be relatively movable in a direction substantially parallel to the flat surface to be ground whereby the flat surface is ground in a cutting manner, said grinding portion having a wavy form as seen looking edgewise thereat.

11. The grinding wheel of claim 10 wherein said grindstone is a self-supporting thin annular shell of electrodeposited super abrasive grains, said shell consisting of said radially inner and outer portions, said shell radially inner portion being fixed to and carried by said cup, said shell radially outer portion cantilevering outward from said cup.

12. The grinding wheel of claim 11 wherein said super abrasive grains are of diamond abrasive.

13. The grinding wheel of claim 11 wherein said super abrasive grains are of cubic system boron nitride abrasive.

14. The grinding wheel of claim 10 wherein the hard and brittle material is any one of silicon and glass.

15. A grinding wheel for grinding the flat surface of a hard and brittle material, comprising:

a cup rotatable about an axis substantially perpendicular to the flat surface to be ground and having a downward facing open end; and

a one-piece annular grindstone, said grindstone being a thin open-center conical skirt of thickness in the range of about 0.1 to about 0.5 mm, said grindstone protruding downwardly and radially outwardly away from the open end of said cup at an inclination to said axis, the downward facing open end of said cup having an annular surface inclined in conformance to the inclination of said grindstone and to which the radially inner part of the upper width surface of the grindstone is affixed to fixedly depend the grindstone from the open end of the cup, the thickness of the grindstone being substantially less than its width along its inclination and than its circumference, a substantial portion of the inclined width of said grindstone being cantilevered out from said cup, such that the radially inner and outer portions of the width of grindstone are respectively backed by and free of backing by said cup, said grinding wheel being positioned so that the outer peripheral edge of said grindstone interferes with the flat surface to be ground, the hard and brittle material and said grinding wheel being adapted to be relatively movable in a direction substantially parallel to the flat surface to be ground whereby the flat surface is ground in a cutting manner, said grinding portion having a wavy form as seen looking edgewise thereat.

16. The grinding wheel of claim 15 wherein said grindstone is a selfsupporting thin annular shell of electrodeposited super hard abrasive grains.