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US 4,048,765 AGranted
Non-cellular polyurethane wheel in a process for finishing a metal workpiece
AssigneeThe Manufacturers Brush Company
InventorIvar J. Samuelson
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AssigneeThe Manufacturers Brush Company
InventorIvar J. Samuelson
Estimating the term…
A solid polyurethane polishing and finishing wheel is disclosed having a molded annular matrix reinforced at the inner circumference by a series of axially spaced annular fibrous members embedded in the matrix. The radially outer portion of the matrix is free to deform during use and is formed of a flexible elastomeric polyurethane having a no-grain Shore A durometer hardness from about 30 to about 55 and a high tensile strength. Proper distribution of the abrasive refractory grains is achieved by employing a polyurethane prepolymer having a high viscosity of 2000 to 6000 centipoises at the curing temperature, and the curing agent is selected to provide the required flexibility and tensile strength and also to effect curing rapidly so that the abrasive grains remain in position during curing. The polyurethane composition contains up to 100 parts of finely divided abrasive material, 3 to 20 parts of mica, and up to 10 parts of molybdenum disulfide per 100 parts by weight of the polyurethane prepolymer. The polyurethane polishing and finishing wheels of the present invention have a useful life at least several times that of the flexible wheels previously used and make it commercially practical for the first time to employ such wheels on machines such as O.D. grinders, centerless grinding machines and the like.
A process for finishing a metal workpiece without significant stock removal comprising rotating the workpiece about its axis while contacting the external surface thereof with the external peripheral surface of a circular finishing wheel having a peripheral speed from about 5000 to about 9000 surface feet per minute, characterized in that said finishing wheel comprises a dense molded non-cellular annular matrix having a circumferential reinforcing means, the radially outer portion of said matrix being deformable and being formed of a cured solid elastomeric polyurethane composition having a no-grain Shore A durometer hardness from about 30 to about 55 and a tensile strength of at least 4000 pounds per square inch and being capable of being elongated several hundred percent, said composition comprising a solid linear polyurethane which is the reaction product of a long-chain polyol having terminal hydroxyl groups and a molecular weight of at least 500 and an organic polyisocyanate having 2 to 3 functional isocyanato groups, said composition containing, per 100 parts by weight of said polyurethane, at least 50 parts by weight of finely divided abrasive refractory grains.
Dependencies are inferred from the claim text.