METAL DETECTING DEVICE FOR PNEUMATIC ROCK DRILL

摘要

PURPOSE: To provide a metal detecting device for a pneumatic rock drill which, in the case of crushing a substance such as a concrete floor or the like, can prevent the destruction of a metal pipe provided buriedly in the substance. CONSTITUTION: A metal detecting device has a metal sensor 10 for detecting a bit 4 coming into contact with a metal pipe 7 buriedly provided inside a concrete floor 5 to output a detection signal; a solenoid valve 11 interposedly provided in an air supply passage 2; an air pipe line 13 branched from the air supply passage 2; and the second solenoid valve 14 connected to the air pipe line 13. The solenoid valve 11 is closed in response to the output of a detection signal to stop the function of the bit 4 and, at the same time, to open another solenoid valve 14 for emitting a compressed air enclosed in the air supply passage 2 into the atmosphere. Thus an electric wire inserted in a metal pipe can be surely protected against a disconnection accident.