MANUFACTURING PROCESS FOR ELECTRICAL MACHINE BRUSHES Russian patent published in 1998 - IPC

FIELD: electrical engineering. SUBSTANCE: process involves preparation of solid starting material components including high-temperature coal-tar pitch, pitch cooking, mixing of components, rolling and milling of mass, cooling, crushing, compression, heat treatment, production of blanks, and their impregnation; novelty is that pitch is first crushed, then mixed up with other components without heating for 45-75 min, then mixer heater is turned on and pitch is pre-cooked and mixed with components to 130 C at a time at rate of temperature rise of 80-90 C/h in environment of escaping volatile products with mixer cover held closed, then to 160 C at rate of temperature rise of 20-30 C/h with mixer cover held open and volatile products removed from mixture; final cooking of pitch and compression of mixture is effected on rolls at hot roll temperature of 135-170 C or in mill at 160-200 C; amount of remaining volatile products in mass is to be between 17 and 24 mass percent. Porous structure of brushes is regulated due to stabilization of pitch cooking process simultaneously with its mixing with filler particles with the result that content of impregnating materials increases 1.5- 2.0 times, friction coefficient at contact point reduces 1.1- 1.7 times, and in-service wear of brushes decreases 2.0-3.1 times. EFFECT: improved quality of brushes. 1 tbl