Apparatus for making precisely partitioned bulbous-shape container

Claim 1

An improved injection-blow molding apparatus for injection molding a relatively deep preform of thermoplastic material and for blow mold converting such a preform into a closed-bottom container, said apparatus including a butt plate assembly, a male mandrel which is cantilevered from said butt plate assembly so that it has an unsupported distal end and which mandrel has a sufficiently large slenderness ratio that its cantilevered strength is insufficient to substantially obviate displacement of its distal end when subjected to unevenly distributed pressure during injection molding cycles, an injection molding body, an injection head assembly, a blow molding body, means for associating the butt plate assembly, the male mandrel, the injection molding body and the injection head assembly to form an injection mold cavity, means for injecting thermoplastic material into the injection mold cavity to form a said preform, means for disassociating the injection molding body and the injection head assembly from the butt plate assembly and the mandrel and for associating the blow molding body with the butt plate assembly and the mandrel so that a blow molding cavity is formed about said preform, means for conducting a blow molding medium into said preform so that said preform is converted into said container, and means for removing said container from said apparatus, said improvement comprising a blow-molding-medium passageway in the mandrel which terminates at a hole in the distal end of the mandrel, an improved injection head assembly, and an improved blow molding body, said improved injection head assembly comprising means for sealing said hole in the distal end of the mandrel and for mechanically supporting the distal end of the mandrel to substantially obviate displacement thereof while said preform is being injection molded, and means for defining a tubular extension of said injection mold cavity adjacent said hole in the distal end of the mandrel so that said preform has a hollow tubular extension on its bottom end, said improved blow molding body comprising means for pinching said tubular extension closed as it is being associated with the butt plate assembly and the mandrel so that said container has a closed bottom end.