An improved process is disclosed for making grinding wheels wherein a vinyl resin, such as polystyrene, or other suitable thermoplastic material is incorporated in the refractory composition with an epoxy binder or other binder which cures in the proper temperature range. The flat surface grinding wheels made in accordance with the invention and used on double-disc grinders function more effectively and facilitate rapid grinding and their useful life can be increased at least 3 or 4 times.
REFERENCE TO RELATED APPLICATION
The present application is a continuation-in-part of copending application Ser. No. 359,737, filed May 14, 1973, now abandoned, which is incorporated herein by reference.
The present invention relates generally to abrasive stone pads for use in processing workpiece surfaces. The abrasive stones generally are produced by combining a phenolic resin mixture with a diluent and then injecting microballoon structures into the resin/diluent mixture to create a porous solution. The diluent is initially ball milled with an abrasive in a tumbler to eliminate the agglomerates and is then added to a resin monomer. A suitable catalyst is added to the mixture to create a chemical reaction, further increasing the porocity of the substance. The mixture is poured into molds and with through a filter or frit plate to remove excess resin and diluent. Finally, the mixture is cured, creating abrasive stones having a uniform surface and bulk structure with a uniform hardness, suitable for workpiece grinding.
The instant invention relates generally to abrasive stones for use in processing workpiece surfaces. The abrasive stones generally are produced by combining an epoxy novalac resin mixture with microballoons and a catalyst. The mixture is put into a mold, cold pressed, and then cured, creating abrasive stones having a uniform surface and bulk structure with a uniform hardness, suitable for workpiece processing.
A resinoid grinding wheel of the present invention has low grinding resistance and is capable of providing a ground workpiece excellent in ground surface quality without burn mark while maintaining essential properties of the resinoid grinding wheel such as low elastic modulus and strong force for holding abrasive grains. A typical resinoid grinding wheel of the present invention includes 25 parts by volume of Al.sub.2 O.sub.3 abrasive grains with grain size of #150, 20 parts by volume of organic hollow material with average particle diameter of 80 .mu.m, and 10 parts by volume of pores having 1 mm in size. They are all dispersed in 40 parts by weight of a bond made of cured epoxy resin.
A new grinding medium consisting essentially of a synthetic resin matrix in which small-sized foam, coarse powdery abrasives and fine powdery abrasives are dispersed is provided. A powder having a low electric resistance is added to the medium to form relatively large-sized foam around the powder. The medium is preferably produced by softening and blocking a synthetic resin powder by high-frequency dielectric heating to form a matrix of the synthetic resin and dispersing small-sized foam, coarse powdery abrasives, fine powdery abrasives and powder having a low electic resistance in the synthetic resin matrix wherein relatively large-sized foam is formed around the powder. The medium has a high ability of abrasion and the surface of the medium is smoothly renewed during the grinding process so that the medium has an excellent grinding effectiveness.
