DETECTING DEVICE FOR DRILL BREAKDOWN OF PERFORATOR FOR PRINTED CIRCUIT BOARD

摘要

PURPOSE:To surely detect the breakdown of a small diameter drill by constituting so as to detect the breakdown of a drill by monitoring the level of the AE signal generated at the perforating time of a printed circuit board. CONSTITUTION:Upon descent of a spindle motor an upper end detecting switch 14 is turned off and a timing T2 is generated. A peak hold 13e becomes zero potential by the timing T2 and the AE signal for the period a timing T1 continuous is subjected to peak holding. A lower end detecting switch 15 becomes on and a spindle motor is then ascended. Upon its ascent the lower end detecting switch 15 is turned off and a timing T3 is formed. The peak hold 13e becomes zero potential by working with a broken drill, an abnormality holding circuit 13i is actuated by the timing T3 and an abnormal signal is output. If a drill breakdown is generated, the abnormality is detected at the spindle motor ascent time of the succeeding work cycle.