Abstract

This study offers a method applied in injection mould with automatic thread demoulding by using servo control and the combination of mechanical structures. In injection moulding, using hydraulic motor to drive gears and cores with thread for automatically taking plastic-injected parts with thread off from the cores is a common method for thread demoulding. The thread demoulding is completed by two movements. One of them is realized by the rotation of the threaded cores driven by hydraulic motor; the other is to stop the injected plastic part from turning and meanwhile push it out by a pushing plate. The pushing plate is usually driven by springs which give forces that vary with the distance the plate travels. Because of this, the displacement of the pushing plate might be different from that of displacement of the core thread goes along the core axis. Thus the parts moulded may be damaged at the thread area on the part when the automatic thread demoulding is proceeding. This technique needs much to be improved hereon in injection moulding. In this study, the author brings up a solution that the hydraulic motor is replaced by a step motor and the pushing plate is driven by a servo motor. And there is a programmable logic controller to synchronize the two movements driven by the motors. Through the improvement the mechanism is substantially enhanced compared with the spring-driven pushing demoulding system.

Keywords:

Injection mould, programmable logic control, servo motor, synchronization, thread demoulding, zero drifting,

References

Competing interests

The authors have no competing interests.

Open Access Policy

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Copyright

The authors have no competing interests.