Device and method for feeding molten plastic material into a molding cavity

A device for feeding molten plastic material into a molding cavity, said device comprising a melting chamber communicated with:

• a portion, susceptible to vibrating, of a sonotrode of an ultrasonic transducer;
• an access for loading a solid plastic material;
• and
• at least one outlet opening of the melting chamber for supplying molten plastic material to said molding cavity;
• said device including translation means for providing relative movement between the portion of the sonotrode and the melting chamber, regulating the position of a tip of the portion of the sonotrode within the melting chamber;
• wherein the device further comprises:
• resistance sensors provided for detecting the resistance against movement which a plastic material, loaded by way of metering in said melting chamber through said access, has against the relative movement between the portion of the sonotrode and said melting chamber;
• a programmable electronic control device for regulating said translation means based at least on the information provided by said resistance sensors;
• and
• cooling means for cooling the portion of the sonotrode, including a coolant gas diffuser arranged around an inlet of the portion of the sonotrode in the melting chamber, provided for diffusing said coolant gas over a portion of the sonotrode extracted from said melting chamber.