IT1255028B - Improved injection assembly, especially for thermoplastic synthetic material - Google Patents

Abstract

The present invention refers to an improved injection assembly, especially for thermoplastic synthetic material. The injection assembly comprises a feed channel which is closed, at one of its longitudinal extremities, by an injection needle, and which accommodates, in rotary manner, a worm which can be actuated by rotary motion about its axis and by translatory motion along the same axis to produce an advancement of the material being injected along the feed channel. Between the axial extremity of the worm and the injection nozzle there is arranged a check valve comprising a stem, coaxially associated with the worm, and a body of the valve, essentially cylindrical, which is mounted around the stem and inside which there is defined an axial passageway for the material being injected. The body of the valve can move along the stem between a front axial shoulder, defined by a tip connected to the free end of the stem facing the injection nozzle, and a rear axial shoulder defined by a closing element connected to the worm to produce the closing of the aforesaid axial passageway when the valve body rests against the closing element. The injection assembly comprises means of actuation which act upon command on the valve body to produce its displacement in the direction of the closing element, independently of the axial displacement of the worm along the feed channel. <IMAGE>