Graphite containing metal bonded diamond abrasive wheels

• US 3,925,035 A
• Filed: 01/12/1973
• Issued: 12/09/1975
• Est. Priority Date: 02/22/1972
• Status: Expired due to Term

• Current Assignee: Paul P. Keat
• Original Assignee: Paul P. Keat
• Inventors: Keat, Paul P.
• Primary Examiner(s): Arnold, Donald J.
• Application Number:
  US05/323,244
• Time in Patent Office: 1,061 Days
• Field of Search: 51/295,298,309
• US Class Current: 51/309
• CPC Class Codes: B24D 3/342 incorporated in the bonding agent

Abstract

The addition of graphite or similarly acting inert fillers to metal bonds for diamond abrasive grinding wheels improves performance of cup-type wheels in the dry grinding of cemented carbides. Filler contents of 15 to 50% by volume of the bond, and particle sizes of from 1 micron to 200 microns are useful. Metal coated diamonds show superior performance under many grinding conditions. However under the most severe conditions when localized grinding temperatures are high, uncoated diamonds are superior. Friable type diamond, of the type normally employed in resin bonded wheels must be used. Bonds melt above 300*C. Hardness of bond correlates with amount of filler required, as does bond volume % of filler.

Claims

1. A CUP-TYPE DRY GRINDING WHEEL HAVING AN ABRASIVE SECTION CONSISTING OF RESIN BOND TYPE DIAMOND ABRASIVE GRAINS BONDED IN A METAL MATRIX HAVING A MELTING POINT ABOUT 300*C. SAID METAL MATRIX INCLUDING A FILLER SELECTED FROM THE GROUP CONSISTING OF PARTICULATE POLYTETRAFLUOROETHYLENE, GRAPHITE, HEXAGONAL BORON NITRIDE, MOLYBDENUM DISULFIDE, AND MIXTURES THEREOF IN THE AMOUNT OF FROM 15 TO 50% BY VOLUME OF THE BOND, SAID FILLER HAVING A PARTICLE SIZE OF BETWEEN 1 MICRON AND 200 MICRONS, THE SMALLER SIZE FILLER BEING PRESENT AT THE LOWER CONCENTRATIONS OF FILLER, THE LARGER SIZE FILLER BEING PRESENT AT THE HIGHER FILLER CONCENTRATIONS, SAID DIAMOND ABRASIVE GRIT BEING DEFINED BY ONE OF THE FOLLOWING LISTS (A), AND (B) OF CHARACTERISTICS:

(A) SYNTHETIC MULTICRYSTALLINE DIAMOND HAVING AN IRREGULAR SURFACE AND A FRIABILITY INDEX F, FOR GRIT SIZES OF 130 AND COARSER EQUAL TO OR LESS THAN 0.0052S2, AND EQUAL TO OR LESS THAN 1.07S0.9, FOR GRIT SIZES FINER THAN 130, WHEREIN S IS THE ARITHMETIC AVERAGE OF THE NUMBER DESIGNATIONS OF THE U.S. STANDARD SIEVE SERIES SCREENS USED TO OBTAIN A SIZED SAMPLE OF THE DIAMOND, AND (B) NATURAL MONOCRYSTALLINE DIAMOND WITH A FRIABILITY INDEX OF LESS THAN 11.3S**0.43 AND IS SELECTED FROM A POPULATION HAVING A BULK DENSITY OF 1.7 OR LESS IN THE 140/170 GRIT SIZE AND 1.6 OR LESS IN THE 200/230 GRIT SIZE AS MEASURED BY THE AMERICAN NATIONAL STANDARDS INSTITUTE METHOD.

2. A grinding wheel as in claim 1 in which a continuous film of a metal having a melting point above 500*C coats the diamond abrasive grains.

3. A grinding wheel as in claim 1 in which the metal matrix has a hardness at 300* to 500*C equal to or greater than that of silver at 300* to 500*C.

4. A grinding wheel as in claim 1, in which the matrix material includes an intermetallic compound.

5. A grinding wheel as in claim 1 in which the filler is graphite.