Resin bonded grinding wheel containing gas-filled thermoplastic resin beads and method of making it

Claim 2

A PROCESS OF THE CHARACTER DESCRIBED COMPRISING REACTING EPICHLOROHYDRIN WITH BISPHENOL A TO PROVIDE A LIQUID CONDENSAATION PRODUCT WITH AN EPOXIDE EQUIVALENT OF AT LEAST 180 AND A MOLECULAR WEIGHT OF ABOUT 350 TO ABOUT 400, MIXING SAID CONDENSATION PRODUCT WITH AN AROMATIC DIAMINE CURING AGENT TO FORM AN EPOXY RESIN BINDER, MIXING ONE PART OF SAID EPOXY RESIN BINDER WITH ABOUT 5 TO ABOUT 7 PARTS BY WEIGHT OF ALUMINUM OXIDE HAVING A PARTICLE SIZE FROM ABOUT 36 GRIT TO ABOUT 80 GRIT, WITH ABOUT 10 TO 30 PARTS BY WEIGHT OF MICA AND WITH GAS-FILLED POLYSTYRENE BEADS WITH A DIAMETER FROM 0.05 TO 0.2 INCH AND A DENSITY FROM ABOUT 1.5 TO 10 POUNDS PER CUBIC FOOT TO FORM A COMPOSITION CONTAINING AT LEAST 50 PERCENT BY VOLUME OF SAID ALUMINUM OXIDE AND FROM ABOUT 10 TO 30 PERCENT BY VOLUME OF SAID POLYSTYRENE, AND HEATING SAID COMPOSITION TO A TEMPERATURE NOT IN EXCESS OF 350*F. FOR AT LEAST SEVERAL HOURS TO HARDEN AND SET THE SAME.

Claim 3

A process according to claim 1 wherein said composition is cured for 3 to 8 hours at a temperature of from about 300* to about 350*F. to form a surface grinding wheel.

Claim 4

A process comprising forming a surface grinding wheel from a refractory composition comprising a major amount of volume of abrasive refractory grains having a particle size of from about 36 mesh to about 80 mesh, from about 10 to about 30 percent by volume of gas-filled organic thermoplastic synthetic resin beads with a diameter from 0.05 to 0.15 inch, and a thermosetting synthetic resin binder which can be cured at a temperature of 450*F. or below, the amount by weight of said refractory grains being from about 4 to about 8 times the total weight of said resin binder, and heating said composition to harden and cure the same without melting all of said beads so that the beads from voids in the cured wheel, said beads being formed of a thermoplastic material with a melting point not in excess of 500*F.

Claim 5

A process comprising forming a surface grinding wheel from a refractory composition comprising a major amount of volume of abrasive refractory grains having a particle size of from about 36 mesh to about 80 mesh, from about 10 to about 30 percent by volume of gas-filled organic thermoplastic synthetic resin beads with a diameter from 0.05 to 0.15 inch, and a thermosetting synthetic resin binder which can be cured at a temperature of 450*F. or below, the amount by weight of said refractory grains being from about 4 to about 8 times the total weight of said resin binder, and heating said composition to harden and cure the same without melting all of said beads so that the beads from voids in the cured wheel, said beads being formed of a thermoplastic material with a melting point not in excess of 500*F.

Claim 6

A process according to claim 3 wherein said binder is glycidyl ether of a polyhydroxy phenol and has at least two glycidyl ether groups, said thermoplastic beads having a melting point from about 350* to about 500*F., and said refractory composition is cured for at least several hours at a temperature from about 300* to about 350*F., and wherein the amount by weight of said refractory grains is from about 5 to about 7 times the total weight of said epoxy binder.

Claim 7

A process according to claim 3 wherein said binder is a phenolaldehyde resin, said thermoplastic beads have a melting point from about 350* to about 600*F., and said refractory composition is cured from 10 to 50 hours at a temperature from 150* to 450* including at least 2 hours at a temperature from 350* to 450*F. and wherein the amount of weight of said refractory grains is from about 5 to about 9 times the total weight of said binder.

Claim 8

A process according to claim 3 wherein said binder is a polyurethane reaction product of a polyhydric alcohol having a molecular weight of at least 500 and a polyisocyanate having 2 to 3 isocyanato groups, said thermoplastic beads have a melting point from about 350* to about 600*F., and said refractory composition is cured for at least several hours at a temperature from about 300* to about 350*F., and wherein the amount by weight of said refractory grains is from about 3 to about 6 times the total weight of said polyurethane binder.

Claim 9

A process according to claim 3 wherein said grinding wheel has a generally flat grinding face and is rotated about an axis perpendicular to said face at a speed of 4000 to 10,000 surface feet per minute, and wherein said grinding face is moved into engagement with a flat metal surface and an effective cutting action is maintained by causing the exposed beads at the outer surface of said grinding face to melt and break away, thereby minimizing loading and glazing of the wheel.

Claim 10

A refractory epoxy composition for making surface grinding wheels comprising from about 45 to about 75 percent by volume of abrasive refractory grains with a particle size from about 36 to about 80 grit, from about 10 to about 25 percent by volume of organic thermoplastic vinyl resin beads with a particle size substantially greater than that of the refractory grains and no more than 0.2 inch, a diglycidyl ether resin binder which may be cured at a temperature not in excess of 350*F. without melting said beads, the amount by weight of said refraCtory grains being from about 5 to about 7 times the total weight of said binder, and 10 to 30 parts of a filler per 100 parts by weight of said binder.

Claim 11

A refractory epoxy composition for making surface grinding wheels comprising from about 45 to about 75 percent by volume of abrasive refractory grains with a particle size from about 36 to about 80 grit, from about 10 to about 25 percent by volume of organic thermoplastic vinyl resin beads with a particle size substantially greater than that of the refractory grains and no more than 0.2 inch, a diglycidyl ether resin binder which may be cured at a temperature not in excess of 350*F. without melting said beads, the amount by weight of said refraCtory grains being from about 5 to about 7 times the total weight of said binder, and 10 to 30 parts of a filler per 100 parts by weight of said binder.

Claim 12

A rigid molded resin-bonded grinding wheel designed for flat surface grinding and formed by curing a refractory composition comprising a major amount by volume of finely divided abrasive refractory grains having a particle size of from about 36 to about 80 mesh, from about 10 to about 30 percent by volume of gas-filled organic thermoplastic synthetic resin beds having a particle size of from about 0.05 to about 0.2 inch and a density no greater than 5 pounds per cubic foot, at least 10 percent by weight of finely divided inorganic filler, and a thermosetting synthetic resin binder which can be cured at a temperature not in excess of 450*F. to provide a strong rigid structure, and beads having a melting point below 600*F. and sufficient resistance to melting during curing of the wheel to form large voids in the cured wheel, the amount by weight of said refractory grains being from about 4 to about 8 times the total weight of said binder.

Claim 13

A rigid molded resin-bonded grinding wheel designed for flat surface grinding and formed by curing a refractory composition comprising a major amount by volume of finely divided abrasive refractory grains having a particle size of from about 36 to about 80 mesh, from about 10 to about 30 percent by volume of gas-filled organic thermoplastic synthetic resin beds having a particle size of from about 0.05 to about 0.2 inch and a density no greater than 5 pounds per cubic foot, at least 10 percent by weight of finely divided inorganic filler, and a thermosetting synthetic resin binder which can be cured at a temperature not in excess of 450*F. to provide a strong rigid structure, and beads having a melting point below 600*F. and sufficient resistance to melting during curing of the wheel to form large voids in the cured wheel, the amount by weight of said refractory grains being from about 4 to about 8 times the total weight of said binder.

Claim 14

A surface grinding wheel according to claim 9 wherein said binder is selected from the group consisting of phenol-aldehyde resins, polyurethanes, and epoxy resins.

Claim 15

A surface grinding wheel according to claim 9 wherein said beads have a particle size of at least one-eighth inch.

Claim 16

A surface grinding wheel according to claim 9 wherein said beads comprise expanded polystyrene with a density of about 2 to about 4 pounds per cubic foot.

Claim 17

A surface grinding wheel according to claim 9 wherein said beads have a melting point not in excess of 500*F.

Claim 18

A surface grinding wheel according to claim 9 wherein said binder is an epoxy resin, said beads have a melting point not in excess of about 500*F., and wherein the amount by weight of said refractory grains is from about 5 to about 7 times the total weight of said binder.

Claim 19

A surface grinding wheel according to claim 9 wherein said binder is a glycidyl ether of a bisphenol A and said beads having a melting point of from about 350* to about 500*F., a particle size from about 0.05 to about 0.2 inch, and a density from about 1.5 to about 4 pounds per cubic foot.

Claim 20

A rigid molded epoxy-bonded grinding wheel designed for flat surface grinding and formed by curing a refractory composition comprising a major amount by volume of abrasive refractory grains having a particle size of from about 36 to about 80 mesh, from about 10 to about 30 percent by volume of expanded gas-filled organic thermoplastic synthetic resin particles having a particle size of from about 0.05 to about 0.15 and a density no greater than 4 pounds per cubic foot, at least 10 percent by weight of finely divided inorganic filler, and an epoxy resin binder which can be cured at a temperature not in excess of 450*F., said thermoplastic resin having a melting point not in excess of about 500*F., the amount of weight of said refractory grains being from about 5 to about 7 times the total weight of said binder.

Claim 21

A rigid molded epoxy-bonded grinding wheel designed for flat surface grinding and formed by curing a refractory composition comprising a major amount by volume of abrasive refractory grains having a particle size of from about 36 to about 80 mesh, from about 10 to about 30 percent by volume of expanded gas-filled organic thermoplastic synthetic resin particles having a particle size of from about 0.05 to about 0.15 and a density no greater than 4 pounds per cubic foot, at least 10 percent by weight of finely divided inorganic filler, and an epoxy resin binder which can be cured at a temperature not in excess of 450*F., said thermoplastic resin having a melting point not in excess of about 500*F., the amount of weight of said refractory grains being from about 5 to about 7 times the total weight of said binder.

Claim 22

A surface grinding wheel having a flat grinding face located substantially in a plane perpendicular to the axis of rotation with a radial width of 1 to 6 inches and a diameter of at least 1 foot, said grinding face being formed a from a curable refractory composition comprising a major amount by volume of abrasive refractory grains having a particle size of from about 30 to about 80 grit and being selected from the group consisting of aluminum oxide and silicon carbide, from about 10 to about 30 percent by volume of gas-filled organic thermoplastic synthetic resin beads having a melting point not in excess of 500*F. and a particle size from about 0.05 to about 0.2 inch, at least 10 percent by weight of a finely divided inorganic filler, and a thermosetting synthetic resin binder which can be cured at a temperature below the melting point of the beads, the amount by weight of said refractory grains being from about 4 to about 8 times the total weight of said binder, the amount of said filler being up to 30 percent by weight.

Claim 23

A surface grinding wheel having a flat grinding face located substantially in a plane perpendicular to the axis of rotation with a radial width of 1 to 6 inches and a diameter of at least 1 foot, said grinding face being formed a from a curable refractory composition comprising a major amount by volume of abrasive refractory grains having a particle size of from about 30 to about 80 grit and being selected from the group consisting of aluminum oxide and silicon carbide, from about 10 to about 30 percent by volume of gas-filled organic thermoplastic synthetic resin beads having a melting point not in excess of 500*F. and a particle size from about 0.05 to about 0.2 inch, at least 10 percent by weight of a finely divided inorganic filler, and a thermosetting synthetic resin binder which can be cured at a temperature below the melting point of the beads, the amount by weight of said refractory grains being from about 4 to about 8 times the total weight of said binder, the amount of said filler being up to 30 percent by weight.

Claim 24

A surface grinding wheel according to claim 17 wherein said thermosetting binder is a rigid high-density polyurethane formed by reacting a polyisocyanate having 2 to 3 isocyanato groups with a polyol having 2 to 4 terminal hydroxyl groups and an equivalent weight of from about 100 to about 1000.

Claim 25

A surface grinding wheel according to claim 17 wherein said thermosetting binder is formed by reacting a molar excess of formaldehyde with phenol and wherein said beads are formed of a vinyl resin.

Claim 26

A surface grinding wheel according to claim 17 wherein said refractory composition contains at least 14 percent by volume of thermoplastic beads with a particle size of at least one-eighth inch.

Claim 27

A high-strength surface grinding wheel according to claim 17 having a specific gravity from about 1.8 to about 2.1, a grade of B to J and a structure of 8 to 16.

Claim 28

A surface grinding wheel according to claim 21 wherein the refractory grains are aluminum oxide and the resin binder is a diglycidyl ether of a bisphenol.

Claim 29

A surface grinding wheel with a flat grinding face having a radial width of at least 3 inches, said grinding face being formed by curing a refractory composition comprising at least 40 percent by volume of abrasive refractory grains selected from the group consisting of aluminum oxide, silicon carbide and mixtures thereof, from about 10 to about 35 percent by volume of gas-filled organic thermoplastic synthetic resin beads with a density from about 1.5 to about 5 pounds per cubic foot including from about 7 to about 25 percent by volume of beads having a particle size from about 0.03 to about 0.15 inch and from about 20 to about 5 percent by volume of larger beads having a size from about 0.2 to about 0.6 inch, and a thermosetting epoxy resin binder which can be cured at a temperature below the melting point of the beads, the amount by weight of said refractory grains being from about 4 to about 8 times the total weight of said binder, said beads having a melting point not in excess of 500*F.

Claim 30

A surface grinding wheel with a flat grinding face having a radial width of at least 3 inches, said grinding face being formed by curing a refractory composition comprising at least 40 percent by volume of abrasive refractory grains selected from the group consisting of aluminum oxide, silicon carbide and mixtures thereof, from about 10 to about 35 percent by volume of gas-filled organic thermoplastic synthetic resin beads with a density from about 1.5 to about 5 pounds per cubic foot including from about 7 to about 25 percent by volume of beads having a particle size from about 0.03 to about 0.15 inch and from about 20 to about 5 percent by volume of larger beads having a size from about 0.2 to about 0.6 inch, and a thermosetting epoxy resin binder which can be cured at a temperature below the melting point of the beads, the amount by weight of said refractory grains being from about 4 to about 8 times the total weight of said binder, said beads having a melting point not in excess of 500*F.

Claim 31

A surface grinding wheel according to claim 23 wherein said grinding face has a radial width from about 5 to about 20 inches and said larger beads have a diameter from about 0.3 to about 0.6 inch and a density not in excess of 4 pounds per cubic foot.

Claim 32

A rigid molded epoxy-bonded grinding wheel designed for flat surface grinding and formed by curing a refractory composition comprising at least 50 percent by volume of abrasive refractory grains having a particle size of from about 30 to about 100 mesh, from about 5 to about 20 percent by volume of organic thermoplastic synthetic resin beads having a particle size of from about 0.2 to about 0.3 inch and a density no greater than 4 pounds per cubic foot, at least 10 percent by weight of finely divided inorganic filler, and a diglycidyl ether resin binder which can be cured at a temperature not in excess of 350*F., said thermoplastic resin beads having a melting point of from about 350* to about 500*F., the amount by weight of said refractory grains being from about 5 to about 7 times the total weight of said binder.

Claim 33

A rigid molded epoxy-bonded grinding wheel designed for flat surface grinding and formed by curing a refractory composition comprising at least 50 percent by volume of abrasive refractory grains having a particle size of from about 30 to about 100 mesh, from about 5 to about 20 percent by volume of organic thermoplastic synthetic resin beads having a particle size of from about 0.2 to about 0.3 inch and a density no greater than 4 pounds per cubic foot, at least 10 percent by weight of finely divided inorganic filler, and a diglycidyl ether resin binder which can be cured at a temperature not in excess of 350*F., said thermoplastic resin beads having a melting point of from about 350* to about 500*F., the amount by weight of said refractory grains being from about 5 to about 7 times the total weight of said binder.