DRILLING MACHINE HAVING AN ELECTROMAGNETIC BASE

摘要

A drilling machine has a base unit(2) mounted on the lower section of a frame(1) for electromagnetically fixing to a metallic workpiece. A motor (3') driven by electro-drill(3) is equipped with a circular cutting tool(7) and integrally fixed to the frame. A power switch(9') provides power to the drive motor and the electromagnetic base unit. A detector senses the load value of the drill. A first control system compares the load value with a stipulated first reference level and delivers an instruction signal when the load value is greater than this level. A second control system compares the detector load value with a stipulated second reference level which is higher than the first one.