Abstract
A practical cooling ability of air spouted out of C-D nozzle is evaluated on a simple model for heat transfer analysis. An average heat transfer coefficient of the air measures hAve=1540W/m2K in range over 1βz/LPCβ2 independent of nozzle configuration and conditions of supplying air to the cooling area under the correct expansion condition. Cooling air from the C-D nozzle installed at the optimum position z/LPC=1 maximizes its cooling efficiency around grinding point. Practical Nusselt number Nu of the air is also correlated with Reynolds number Re at the exit part of the C-D nozzle to predict the cooling ability in the case of arbitrary supplying air conditions. Surface temperature on work-piece being ground by supplying cooling air is measured to clarify usefulness of practical cooling air grinding. The surface temperature is compared with that by supplying conventional used grinding fluid. The primary consideration shows that the cooling air, Nu of which is above 306, should improve its cooling ability and can cool the grinding point more than the conventional used grinding fluid does. The optimum supply condition of the cooling air is experimentally verified.
