| 摘要 |
PURPOSE:To detect a faulty bottom dead point which can not be disregarded through one magnetic sensor by allowing the magntic sensor to compare the peak value of the bottom dead point detection output regarding a top press die with a peak value mean value, and then driving an alarm circuit. CONSTITUTION:The bottom dead point arrival of the lowered top die 11 of a press is detected by a detector 10 for the die and the magnetic sensor 12 fixed to a bottom die 13 and a displacement gauge circuit 14 equipped with an oscillating circuit 14a, etc., outputs a peak value corresponding to the bottom dead point to a peak holding circuit 16, which holds the peak value. This held value is applied to an averaging processong circuit 17 to calculate the mean value of held values, thereby calculating the difference between said mean value and a held value from the circuit 16. If the obtained difference value exceeds a threshold value for specifying a disregarding range, the alarm circuit 19 is controlled through a fault detecting circuit 18 to generate an alarm. This consititution allows only one magnetic sensor to detect a faulty bottom dead point which is caused by the thermal expansion of the dies, drift of the detector, etc., and can not be disregarded. |
