Magnetic chuck for surface grinder - has motor contactor controlling AC and DC supply for reversal of polarity

摘要

The polarity reversing unit is for use with solenoid-operated clamping plates securing work during machining, and which are supplied via a transformer and a rectifier. It has a motor contactor with a number of contacts, some of which control the alternating-current voltage, particularly before the transformer, and some the direct-current voltage for the clamping plate. The contacts switch the alternating-current voltage on and off several times. The operating voltage is initially maintained and then lowered, while the direct-current contacts reverse the polarity.