TEMPERATURE DURING GRINDING BY INTERRUPTED AND HIGHLY POROUS GRINDING WHEELS

The authors suggested a common approach and work technique for temperature determination while grinding by plain, interrupted and highly porous grinding wheels on the basis of presentation of thermal process during grinding as a single heating and cooling cycle (plain wheels) or as a complex of such cycles (interrupted and highly porous wheels). According to this presentation, the authors suggested distinguishing macro- and micro-interrupted grinding, respectively, for grinding by interrupted (macro-interrupted) and highly porous (micro-interrupted) grinding wheels. In this case, the principle of superposition of thermal fields caused by positive and negative heat source successive exposure on the processed surface at macro- and micro-levels is used according to the frequency of this exposure. The study showed that the increase of number of cutting ledges on the interrupted wheel at a constant duty cycle for these ledges circular pitch (the inverse value for pulse relative duration of heat flow) causes the reduction of grinding temperature under otherwise equal conditions. Equal grinding rate of wheels of compared designs is one of these conditions.  The same trend for grinding temperature reduction takes place when increasing the duty cycle for circular pitch at a constant number of cutting ledges. The authors determined that the increase in quantity of cutting ledges on the wheel periphery causes the decrease of duty cycle influence on the temperature. The regularity of interrupted grinding temperature decrease during the increase of cutting ledges number and duty cycle (under otherwise equal conditions) confirms the validity of the discernible trend for replacing the plain interrupted wheels (macro-interrupted) with the highly porous grinding wheels (micro-interrupted) appropriate by overall dimensions. The authors present the technique for grinding temperature determination while grinding by the highly porous wheels which can be used when designing the optimal composition for these wheels and selecting their components.