Nozzle For The Production Of Hollow Bodies Of Thermoplastic Material By Extrusion Blow Molding

Abstract

The invention concerns a nozzle for the production of hollow bodies of thermoplastic material by extrusion blow molding. According to the invention, continuous extrusion of at least two preforms in web form of plasticized material is effected by means of a plurality of extrusion devices. The preforms are jointly shaped to form a hollow body in the still plastic condition, that is to say, in the first heat, within a multi-part tool forming a mold cavity. In that case, a wall thickness profile is imparted to at least one preform during the extrusion operation independently of the respective other preform by continuous nozzle gap adjustment during the extrusion operation.

1 . A wide-slot nozzle for imparting a thickness profile to a preform along the width and length direction of said preform comprising;
 a nozzle body; and   at least two tool lips delimiting a nozzle gap;   wherein said preform further includes a wall thickness and wherein adjustment of at least one of said at least two tool lips causes said nozzle gap to be narrowed or enlarged resulting in a change in the wall thickness of said preform.   
     
     
         2 . The wide-slot nozzle of  claim 1  wherein said nozzle body is adjustable in portion-wise manner in the width direction to effect portion-wise adjustment of said nozzle gap. 
     
     
         3 . The wide-slot nozzle of  claim 1  wherein said at least one of said at least two tool lips is of a pliable nature. 
     
     
         4 . The wide-slot nozzle of  claim 1  wherein a first of said at least two tool lips is displaceable uniformly over the depth of the nozzle gap and the second of said at least two tool lips is in the form of a counterpart lip which is oppositely deformable in portion-wise manner in the width direction of said nozzle gap.