JPS57205068A - Automatic grinding unit - Google Patents

Abstract

PURPOSE:To contrive to prevent wear of a grinding stone by a method wherein torque to be applied to a grinder motor is invariably kept constant through automatic control so that grinding the surface of a work more than needed can automatically be prevented. CONSTITUTION:A converter 16 located between a three-phase high-frequency generator 15 and a grinder motor 5 functions to convert the alternating current flowing into the motor to the direct current, leading a D.C. output into a comparator 17. The output is further led into a turbo unit 18 after the comparison of a voltage of the converter 16 with a voltage set by a voltage setter 17a which is disposed in the comparator 17 and capable of setting a desired value of voltage. When a grinding stone 2 is in an unloaded state, the output voltage of the comparator 17 is positive, so that the grinding stone 2 automatically advances toward the surface of a work to be ground where the grinding stone grinds the work while being moved to the right and left by the other motor 12. When, however, the grinding stone has come in contact with other surface than the welded section B which requires grinding, a surface area of the work being ground by the grinding stone increases, thereby increasing the current which flows into the motor 5 and accordingly automatically moving the grinding stone 2 backwardly.