System for making a hollow-shaped body from molten resin by injection molding

Abstract

Abstract A system is disclosed for making a hollow-shaped body from molten resin wherein the method includes the step of cutting a hole through the resin after it is cooled and into a fluid aperture formed during a fluid injection step which distributes the molten resin over the interior surfaces of a mold of the system. The fluid aperture is in communication with the interior of the resulting hollow-shaped body and is preferably located in the runner or sprue of the mold. The fluid is preferably a gas, such as nitrogen. In each of the disclosed embodiments of the invention, a cutting member is located in the mold and has a surface which at least partially defines a resin flow path in the mold. Cutting is accomplished by moving the cutting member in a controlled fashion between a molding position and a relieving position so that the cutting member applies a cutting force to cut the hole. The cutting member includes a fluid-relieving aperture formed therein. The fluid-relieving aperture is in fluid communication with the fluid aperture in the relieving position of the cutting member to relieve the pressure through the fluid-relieving aperture. In some of the disclosed embodiments, the cutting force is a shear force which is applied tangential to the cooled resin. In another disclosed embodiment, the cutting force is applied substantially perpendicular to the cooled resin. The cutting member is movable linearly in one embodiment and is movable in a rotary fashion in another embodiment.

Inventors

• 👤 Hubert Kauer

Bibliographic Details