Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
  • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
  • B24D3/34—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents characterised by additives enhancing special physical properties, e.g. wear resistance, electric conductivity, self-cleaning properties
  • B24D3/342—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents characterised by additives enhancing special physical properties, e.g. wear resistance, electric conductivity, self-cleaning properties incorporated in the bonding agent
  • B24D3/344—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents characterised by additives enhancing special physical properties, e.g. wear resistance, electric conductivity, self-cleaning properties incorporated in the bonding agent the bonding agent being organic

Definitions

• This invention relates to organic bonded grinding wheels containing cubic boron nitride abrasive and active fillers.
• active fillers such as metal sulfide and halogen salts such as cryolite which have reactivity toward the material being ground have been employed in conventional aluminum oxide abrasive containing organic bonded grinding wheels for many years.
• Such grinding aid fillers have not been used in grinding wheels containing diamond grits as the abrasive, because the important use of diamond wheels is in grinding carbides, glass and ceramics, particularly (for resin bonded wheels) in grinding hard carbides. Grinding aids suitable for grinding steel, for example, are of no apparent advantage in carbide grinding.
• CBN cubic boron nitride
• British Patent 834,351 published in 1960 teaches the use of metal sulfides together with alkali-metal salts such as sulfates as fillers in conventional abrasive wheels for grinding alloy steels. While the patent refers to abrasives generally, and lists diamond, such fillers, so far as is known, have never been commercially employed in diamond wheels or in CBN wheels.
• German Patent P2230701 to Winter & Sohn discloses employing zinc sulfide with cryolite as a grinding aid in stick form to be applied to the workpiece. No suggestion of incorporating the grinding aids in the wheel bond appears in the patent.
• a resin-bonded grinding wheel containing cubic boron nitride abrasive grits wherein the resinous bonding matrix contains, as a filler, (1) iron sulfide and an alkali sulfate in a volume ratio of 1/4 to 4/1, (2) cryolite, or (3) potassium aluminum fluoride, or a mixture of (1), (2), and/or (3), in the amount of 8 to 50% by volume of the abrasive, bond, and filler combination.
• the present invention is the inclusion in CBN organic resin bonded wheels of an iron sulfide filler together with sodium or potassium sulfate.
• Somewhat inferior to the iron sulfide/alkali sulfate filler are cryolite, or potassium aluminum tetrafluoride, or hexafluoride, in the amount of 8 to 50% by volume of the grinding section of the tool. Obviously, combinations of these fillers can be employed.
• Such wheels in dry grinding of tool steels, or grinding of tool steels in combination with cemented carbides, show equivalent or better results than the best prior art wheels using bond compositions containing silver and dry film lubricants. Elimination of the need for silver is a major economic benefit. These wheels also are advantageous in providing greater freeness of cut and thus more rapid cut of the workpiece.
• Wheels according to the present invention may be prepared as follows:
• fillers are those active materials included as the subject of the application as well as other inert substances.
• the mixture is then coated with a liquid pickup agent.
• a finely divided powdered resin is then mixed with the liquid coated abrasive/filler mixture so as to coat the surfaces of the abrasive and filler particles evenly with resin.
• phenolic novolak resin with hexamethylene tetramine crosslinking agent is chosen as the resin and furfural as the liquid pickup agent.
• a typical formulation which illustrates the invention is:
• the core is composed of finely divided aluminum powder and resin which has previously been compressed either cold or hot.
• the wheel which now consists of the core and circumferentially located abrasive section, is hot pressed to melt and fuse the resin bonding both the abrasive section and the core. Pressures to 50 tsi and temperatures from 140 to 200°C. are applied to the wheel during a period of one-quarter to one hour to form the wheel. Subsequent to this operation the wheel may be heated to a temperature higher than the molding temperature at atmospheric pressure to improve grinding characteristics. Finally, the wheel is machined to prepare a product to standard and fixed dimensional specifications.
• the wheels may be straight cylindrical wheels (lAl shape), or may be cup wheels as in the example above, or may be any other conventional shape.
• the active filler should be present in a total amount of from 8% to 50% by volume of the grinding section of the wheel.
• the ratio of FeS 2 to alkali sulfate may be from 4/1 to 1/4 by volume, but is preferably from 40/60 to 60/40 by volume.
• Sodium sulfate may replace all or part of the K 2 SO 4 .

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Polishing Bodies And Polishing Tools (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=22928362

Family Applications (1)

Country Status (9)

Cited By (5)

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Citations (6)

Family Cites Families (2)

• 1982
  • 1982-02-11 CA CA000396042A patent/CA1188103A/en not_active Expired
  • 1982-02-24 ZA ZA821215A patent/ZA821215B/xx unknown
  • 1982-02-25 AU AU80800/82A patent/AU8080082A/en not_active Abandoned
  • 1982-03-01 IN IN233/CAL/82A patent/IN155234B/en unknown
  • 1982-03-04 EP EP82101696A patent/EP0061035A3/de not_active Withdrawn
  • 1982-03-04 DE DE198282101696T patent/DE61035T1/de active Pending
  • 1982-03-12 ES ES510379A patent/ES8308245A1/es not_active Expired
  • 1982-03-15 JP JP57039607A patent/JPS57163067A/ja active Pending
  • 1982-03-15 BR BR8201393A patent/BR8201393A/pt unknown

Patent Citations (6)

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