Abstract This invention relates to brushes for electrical apparatus and to methods for manufacturing same. Carbon and electrographitized brushes for electrical apparatus include, according to the invention, finely divided abrasive additions uniformly distributed throughout the whole volume of the brushes, mainly, in the form of silicon dioxide, and filmforming organic polymers, such as cobalt linoleate or polyimide resins, in a polymerized state. The method for manufacturing said brushes consists in that brush blanks are subjected to combination treatment, for which purpose into the blanks are introduced uniformly throughout the whole volume thereof finely divided abrasive additions, mainly, in the form of silicon dioxide, whereupon the brush blanks are impregnated with solutions of film-forming organic polymers with subsequent thermal treatment until full polymerization of the impregnating composition.
A method for manufacturing carbon and electrographitized brushes for electrical apparatus which comprises distributing finely divided silicon dioxide throughout the entire volume of a brush blank, subsequently impregnating said blank with a solution of a film-forming organic polymer and subjecting said impregnated brush blank to thermal treatment until complete polymerization of the polymer is effected.
Claim 2
Dependent Claim
55 words
A method according to claim 2 wherein the thermal treatment takes place at 120* to 180*C. and the film forming polymer is natural boiled linseed oil in such an amount that after thermal treatment the blank will contain 2.0 to 5.0 percent by weight of polymerized linseed oil based on the weight of the blank.
Claim 3
Dependent Claim
53 words
A method according to claim 2 wherein the thermal treatment takes place at 100* to 250*C. and the film forming polymer is a polyimide resin in such an amount that after thermal treatment the blank will contain 1.0 to 4.0 percent by weight of polyimide resin based on the weight of the blank.