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

摘要

System (10) for the injection moulding of plastic material comprising: an injection device (12) of the hot runner type for the injection of a plastic material (MP), in the molten state, into a mould (11, 11a, 11b); a circular diaphragm (13) to distribute evenly and circularly in the cavity (11b') of the mould, through a circular injection gate or port (25), the plastic material (MP) injected by the injection device (12), and control means (21, 22, 23, 24) adapted to control the operation of the moulding system and including in particular a heating inductor (21 ), driven in frequency, additional with respect to the heating means (16) provided to heat and keep at a hot temperature the injection device (12), and a thermocouple (22), with both the heating inductor (21 ) and the thermocouple (22) being arranged in the area of the circular injection gate (25); wherein these control means (23, 24) are adapted to control through the heating inductor (21 ), by taking into account the temperature measured by the thermocouple (22) and of the characteristics, in particular rheological and physical (D-1, D-2), of the plastic material used to mould a piece, the temperature (T, T+, T-) of the area of the circular injection gate (25), so as to keep under control in real time the moulding cycle of the piece (PZ). The new system (10) of injection moulding is particularly suitable for moulding pieces (PZ, PZ-10) which typically have a form of a solid of rotation with cylindrical outer surfaces or the like, and is configured in the area of the circular injection port (25) so as to avoid the formation of waste or superfluous parts, such as a sprue, which must be subsequently removed from the piece, once moulded.