What is the secondary drop protection device of the punch press

In the automatic control process of the punch press, the actual position of the crankshaft is detected by limit switches or angle sensors, and then the signal is transmitted to the PLC to control the action of the punch press. However, due to various factors, if the limit switch or angle sensor is damaged during operation and sends an incorrect signal, the PLC will act based on the incorrect signal, which can easily cause serious accidents.

Therefore, in order to increase the safety of the punch press and reduce the occurrence of accidents during the production process, a new type of "dual-drop" protection device has been designed. That is, a proximity switch is installed at the head of the crankshaft to detect the position of the top dead center, and the detected signal is compared with the PLC signal. If there is an anomaly, an alarm will be activated to stop the machine. In a specified operation, if the dual-drop proximity switch installed at the head of the crankshaft fails or becomes loose, the "abnormal alarm" light on the control panel will be constantly lit. If the slide does not stop at the top dead center position after one stroke (during continuous punching), and the dual-drop proximity switch detects a signal at the top dead center position, the dual-drop switch will start to act. It quickly sends a signal through the PLC to cut off the power to the control valve/solenoid, and at the same time, the "abnormal alarm" light on the control panel will be constantly lit.

When using it, there is a dual-drop cam fixed on the crankshaft of the punch press, and an proximity switch is set above the cam. The proximity switch is in contact with the cam and can be fixed on the punch press frame through brackets or other connecting parts. The proximity switch is connected to the input terminal of the PLC, and the output terminal of the PLC is connected to the execution unit that controls the action of the punch press.

In summary, the "dual-drop" of the punch press is a protective device, especially a device that prevents the machine tool from experiencing continuous punching in single operation mode.