PORTABLE DRILLING MACHINE

摘要

Operability and safety are enhanced by preventing occurrence of overload state again after occurrence of overload. An AC power supply (10) is connected with a motor (12) for rotating a drill through a motor control section (28), a current detecting section (30) and a power switch (36), and connected with a magnet (16) through the power switch (36) and a full-wave rectifier (18). The motor control section (28) rotary-drives the motor according to a signal from a main control section based on the fact that a motor start switch (38) is turned on. The main control section (14) controls a voltage supplied to the motor (12) to lower gradually when the motor (12) enters overload state, and to raise the voltage gradually when overload state is eliminated thus performing normal power supply. Furthermore, the main control section (14) controls the motor control section (28) to stop power supply to the motor (12) when overload state sustains for a predetermined time.