System for the injection moulding of plastic material, particularly suitable for the moulding of pieces having the form of a solid of revolution or similar, and corresponding method

A method for the injection moulding of plastic material pieces that exhibit the form of a solid of revolution with external and/or internal cylindrical surfaces, through an injection moulding assembly or system comprising:

• an injection device for the injection of a plastic material, in the molten state, into a mould;
• and
• a circular diaphragm for distributing circularly and evenly into the cavity of a mould, through an opening of a circular injection gate having a circular or annular form, the plastic material that is injected by the injection device;
• wherein the method comprises the following phases:
• detecting, through a temperature sensor, the temperature of the zone of said circular injection gate;
• controlling constantly, through a heating inductor, driven in frequency and arranged in the zone of said circular injection gate, and on the basis of the temperature detected by said sensor, the temperature of the zone of said circular injection gate;
• and
• controlling in real time the phases of the moulding cycle of a piece, including the phases of injection of the plastic material into the mould and of the opening and the closing of the mould, as a function of the temperature, as detected by said sensor, of the zone of said circular injection gate,
• wherein the phases of controlling in real time the temperature of the zone of said circular injection gate and the phases of the moulding cycle of the piece are carried out by taking into account data and, contained in a data base, concerning the characteristics and/or properties of the specific plastic material that is used to mould the piece.