When the thimble action of the hydraulic injection molding machine is abnormal, we can check and remove the faults one by one from the following reasons: first, start the motor oil pump, conduct the front and back actions of the injection table or the glue injection and melting actions under the manual state, if these actions can be carried out normally, then it can be verified that the injection molding machine oil pump, proportional pressure valve, proportional speed valve and related circuits are normal.

Then check whether the parameters of ejector action are set correctly, such as ejector pressure, speed, position and times.

According to the action of the ejector pin, check whether there is any electrical signal on the solenoid coil of the ejector pin reversing valve. Generally, the solenoid coil of each reversing valve uses the DC 24 V voltage, and a small part of the old machine solenoid reversing valve is controlled by the AC 220 V voltage. If there is no voltage signal to, it is possible that two signal lines are disconnected. Check whether the output port of L / O electronic board has voltage output. If not, continue to check whether the power amplifier triode or the intermediate relay at the output is in good condition.

Check whether the resistance value of the solenoid is normal. Generally, the coil may be broken or burnt. Then the solenoid needs to be replaced.

There are foreign matters stuck in the reversing valve element. Generally, foreign matters come from the aging and damage of sealing parts or metal parts in the oil circuit and enter the valve. In this way, they should be disassembled and cleaned.

If the seal in the plunger cylinder is damaged, oil channeling or the piston rod is broken, the movement of the plunger can also be abnormal.

Check whether the limit switch beside the thimble cylinder is in good condition.

I repaired the abnormal movement of the ejector pin of an injection molding machine two days ago: the machine can't eject the product every time it is molded, but it has the jacking action, but it can't reach the set jacking position, so the plastic parts can't be demoulded. It's no use modifying parameters. The die thimble plate is also smooth. Normally, it can be demoulded by setting the jacking position 40mm in the computer. According to the observation of the computer, the jacking position stops at about 17mm each time, and the position value in the jacking process shows the phenomenon of interval jump.

First, check whether the three signal lines of the electronic ruler are in good contact; measure the signal voltage to meet the requirements of the electronic ruler. The "1" and "3" pins of the electronic ruler are connected with the positive and negative ends of the power supply, "2" pin is the output signal end, "4" pin is the ground end.

Take apart the electronic ruler again, the electric brush of the pull rod is still good, but it is dirty. Then, clean the brush and resistance rail with special electronic cleaner, and then apply Vaseline grease for lubrication. Assemble the test machine, everything is normal.

The electronic ruler used in the injection molding machine is actually a sliding rheostat. If it is dirty inside; the resistance rail is broken; or the moving ruler contact spring is worn or deformed; the electric signal line is in poor contact. May cause abnormal movement.

Although the structure of the electronic ruler is simple, be careful when assembling. Especially when installing the electric brush of the pull rod, it is not allowed to deform the electric brush of the elastic piece of the moving ruler. It is necessary to make sure that the electric brush is in good contact with the resistance rail.