​Dual solenoid valves used on small punches are usually pilot-operated. Two are mounted on the brake and clutch respectively, both are normally closed valves. Both valves are controlled by one circuit, in parallel. The characteristic is that any one of them can't act when the other is broken. Usually, the brakes must be opened before the small punching machine is operated, and then the clutch must be combined. The double solenoid valve is set according to this requirement. After the brake valve is energized and opened (at this time, the air can not reach the brake), the control gas routed from the copper pipe to the clutch valve, thereby opening the valve core of the clutch valve, and the clutch can open the large piston. After opening, the control steam will reach the brake through the clutch copper pipe, open the big piston, and then the clutch brake will enter the atmosphere at the same time. The main function is to return the compressed air at the outlet end to the exhaust port when one of the solenoid valves cannot be returned (always supplying air) and the other is working normally. Double solenoid valve is to play a double protection role. ​​

The failure of the solenoid valve will directly affect the normal use of the small punch. The non-action of the solenoid valve is the most common fault of the solenoid valve of the small punch. When dealing with the general fault, the following aspects should be solved:

1. Check whether the electronic valve is leaking. Air leakage can cause insufficient air pressure, making it difficult to open the forced valve, usually caused by the formation of cavity blow-by due to damage to the gasket or wear of the spool valve.

2. Check whether the small punch solenoid valve wiring head is loose or the wire head is falling off, check whether the solenoid valve is energized, and solve it by tightening the wire head.

3. Check whether the solenoid valve of the small punch press is stuck. The operating gap between the solenoid valve coil and the magnet is extremely small (less than 0.008mm), and they are usually assembled in a single piece. When mechanical debris is brought in or there is too little lubricating oil, it is easy to cause jamming. The solution is to use a steel wire to poke into the small hole in the head to make it spring back. The fundamental solution is to remove the solenoid valve, take out the valve core and the valve core sleeve, and clean it with CCI4, so that the valve core can move flexibly in the valve sleeve. When disassembling, pay attention to the installation sequence of each device and the position of external wiring, so as to facilitate reinstallation and correct wiring. At the same time, it is also necessary to check whether the oil spray hole of the lubricator is blocked and whether the lubricating oil is sufficient.

4. Whether the solenoid valve coil of the small punch press is damaged, the wiring of the solenoid valve can be removed and tested with a multimeter. If the test result is an open circuit, it means that the solenoid valve coil is damaged. Usually the reason is that the coil is damp, resulting in poor insulation and magnetic leakage, so that the current in the coil is too large and causes damage. Therefore, it is necessary to ensure that the electronic valve is used in a dry environment. In addition, the spring is too hard, the reaction force is too large, the number of coil turns is too small, and the suction force is not enough, which may also cause the coil to be damaged. Generally, it is solved by replacing the coil. In case of emergency, the manual switch on the coil can be turned from the "0" position during normal operation to the "1" position to make the valve open.