| 摘要 |
PROBLEM TO BE SOLVED: To prevent deviation of a grinding wheel spindle and a grinding wheel center at the time of continuous working, even when a grinding wheel dressing is performed, by performing a control so that a temperature at the time of non-grinding of the grinding wheel spindle may be substantially equal to a temperature at the time of grinding and performing dressing and truing of a grinding wheel by a wheel dressing device at the time of non-grinding. SOLUTION: When a grinding wheel spindle driving motor 19 is rotated, a coolant pump motor 59 and a cooling pump motor 62 are started by a temperature detected by a temperature sensor 65. When a temperature of the grinding wheel spindle driving motor 19 rises and a temperature detected by the temperature sensor 65 becomes higher than a set temperature, a signal from an arithmetic circuit 66 is inputted in a sequence controller 54, the condition of a third block becomes unsatisfactory, the condition of a fourth block is satisfied, the coolant pump motor 59 is stopped and the cooling pump motor 62 is started. As a result, load applied to the grinding wheel spindle driving motor 19 is reduced, the grinding wheel spindle driving motor 19 is cooled, a temperature of a grinding wheel spindle 18 is prevented from rising too high and the temperature of the spindle 18 becomes stable at a slightly higher degree than the set temperature set by the temperature sensor 65.
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