Extrusion molding equipment for multi-layer parison

Claim 1

Extrusion molding equipment for molding a multi-layer parison, which comprises: an accumulator head; a cylindrical member disposed in such accumulator head and having therein a first temperature control means for controlling a chief resin material temperature-wise; a ringed piston reciprocal along the inner peripheral surface of said cylindrical member for further extruding said chief resin material extruded from an extruding means; a first core member coaxially disposed inside said ringed piston; said cylindrical member and said first core member cooperating together to define therebetween an annular resin storing space internally accommodating said ringed piston; an annular die coaxially and securely mounted on said accumulator head at the lower endportion thereof; a second core member coaxially and reciprocably engaged with said first core member at the lower end portion thereof; said cylindrical member, said die and said first core member cooperating together to define an annular resin passage directly communicating said resin storing space at the downstream side thereof, into which resin passage said chief resin material is forcibly extruded by said ringed piston; and at least one ringed member coaxially disposed within said resin passage and having at least one injection opening defined therein, which opening communicates an extruding means for extruding an auxiliary resin material, with a second temperature control means for controlling said auxiliary resin material temperature-wise being arranged in the vicinity of said extruding means and away from said first temperature control means.