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  • Injection molding machine opening and closing mold control needs to pay attention to the problem

Injection molding machine opening and closing mold control needs to pay attention to the problem

Mold opening control.

After the molten plastic is injected into the mold cavity and cooled, the mold is opened and the product is removed. The mold opening process is also divided into three stages. The first stage is slow mold opening to prevent the part from tearing in the mold cavity.

The second stage is fast to shorten the mold opening time. The third stage of slow mold opening is to reduce the impact and vibration caused by mold opening inertia.

Closing control.

Mold closing is to tighten the mold with a huge mechanical thrust to resist the huge opening force caused by the high-pressure injection of molten plastic and the filling of the mold during the injection process.

Close the safety door, each travel switch gives a signal, and the mold closing action starts immediately. Firstly, the moving plate starts at a slow speed, and after a short distance, the lever pressure block, which was holding the slow speed switch, is disengaged and the moving plate is turned to advance rapidly. When advancing to near the end of the die closing, the other end of the lever presses on the slow speed switch again, then the movable plate turns to slow speed and advances with low pressure.

In the process of low-pressure mold closing, if there is no obstacle between the molds, they can be closed smoothly until the high-pressure switch is pressed, and the high-pressure is turned to straighten the machine hinge to complete the closing action. This distance is extremely short, generally only 0.3~1.0mm, just after turning the high pressure rotating immediately touches the mold closing termination limit switch, then the action stops and the mold closing process is finished.

There are fully hydraulic type and mechanical linkage type of mold closing structure of injection molding machine. Regardless of the type of structure, the closing force is finally applied by fully straightening the connecting rod. The straightening process of the connecting rod is the process of the movable plate and the tail plate being held apart, and the process of the four tie rods being stretched by the force.

The magnitude of the clamping force can be known from the highest value of the hydraulic gauge at the moment of closing the mold. Smaller injection molding machines do not come with a mold-closing oil pressure gauge, so it is necessary to judge whether the mold is tight according to the straightening of the connecting rod.

If the connecting rod is easily straightened when a certain injection molding machine is closed, or if it is not straightened by a little bit, or if one of the several pairs of connecting rods is not completely straightened, the mold will be swollen and the parts will have flying edges or other problems.
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