An abrasive composition prepared by kneading abrasive grains and a binder together, with addition of a filler when desired, is molded into a block, which is heated by a high-frequency wave heater and then passed between multiple pairs of rolls and thereby rolled into a sheet. Circular pieces are blanked out from the rolled sheet and subsequently baked to continuously produce resinoid wheels.
In the manufacture of grinding wheels or other grinding products of either the vitrified or organic type, the heat treatment for drying and/or firing or curing respectively is provided by microwave energy so that the heating is progressive from the inside of the wheel to the outside and the process is greatly speeded up. It is also possible according to the invention to include a steel or other metallic reinforcing ring in a grinding wheel without it being damaged or destroyed during firing.
Resinoid abrasive wheels are continuously produced by preparing pore forming granules having predetermined mechanical strength and containing a substance thermally decomposable at a baking temperature for the production of resinoid abrasive wheels, kneading together the pore forming granules, abrasive grins, a binder, a glass fiber reinforcement and a filler to prepare an abrasive composition, molding the abrasive composition into a block, heating the block by a high frequency heater, rolling the heated block into a sheet by rolls, blanking out circular pieces from the sheet, and baking the circular pieces of the uncured abrasive composition containing the pore forming granules uniformly dispersed therein to cure the binder and form pores by the decomposition of at least part of the thermally decomposable substance contained in the granules, whereby resinoid abrasive wheels having pores uniformly dispersed therein are obtained.
Resinoid abrasive wheels are continuously produced by preparing pore forming granules having predetermined mechanical strength and containing a substance thermally decomposable at a baking temperature for the production of resinoid abrasive wheels and a blowing agent, kneading the pore forming granules with abrasive grains and a thermosetting synthetic resin binder to prepare an abrasive composition, molding the abrasive composition into a block, heating the block by a high frequency heater, rolling the heated block into a sheet by a multiplicity of pairs of rolls, blanking out circular pieces from the sheet, and baking the circular pieces to cure the binder therein and form pores by the decomposition of at least part of the thermally decomposable substance contained in the granules and by the decomposition of the blowing agent contained in the granules. The resinoid abrasive wheels obtained have pores uniformly dispersed therein.
Solid material is ground in a grinding mill and caking of the ground particles is substantially eliminated by including particulate water absorbent polymeric material in the mill.
A method for making low porosity resin bonded product containing abrasive grams by preheating the abrasive grain mix prior to pressing and curing to a temperature within a range to just soften or partially liquidy the resin and which does not cure it. The heating is done with dielectric heating field and then the heated mix is cold pressed in a mould to the desired density, and the resin heat cured to produce the finished product.
