US 4,338,068 AGranted

Injection molding device and method

AssigneeMassachusetts Institute of Technology

InventorsNam P. Suh, James R. Rinderle

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Abstract

A novel method and device for precision injection molding is disclosed providing controlled cooling of a portion of the mold cavity surface during the molding cycle, or several such portions independently, and also, in the preferred embodiment controlled heating of a portion of the mold cavity surface during the molding cycle or several such portions independently, whereby high quality, high precision parts having close dimensional tolerances may be produced. Another aspect of the invention, a volume-controlled variable conductance heat pipe is disclosed, which novel heat pipe comprises housing means forming a sealed chamber, fluid, such as water or ammonia, within the chamber, wicking means and control means for controlling the thermal conductance of the heat pipe comprising means for controlling the volume of fluid in the liquid phase in the chamber. Preferably, the novel injection mold comprises a thin mold face supported at least in part by a foundation means which either incorporates, or is itself, a novel volume controlled variable conductance heat pipe as disclosed.

Claims16

Dependent claims

A mold for making injection molded parts comprising:

at least one mold piece, which mold piece defines at least in part a mold cavity;
means for injecting molding material into said mold cavity;
means for heating at least a portion of the mold cavity surface of said mold during the injection of said molding material to maintain the temperature of said injected material at a sufficient level to prevent the molecules of said injected material from solidifying into a specific orientation;
means for cooling at least a portion of the mold cavity surface of said mold;
and
means for controlling the rate of cooling of at least one portion of the mold cavity surface of said mold independently from at least one other portion of the mold cavity surface of said mold so as to maintain selected properties of said injected material substantially uniform throughout said mold cavity, said means for controlling the rate of cooling including at least one heat pipe which has housing means forming a sealed chamber, fluid contained within said sealed chamber, wicking means within said sealed chamber for transporting the liquid phase of said fluid, and control means for controlling the thermal conductance of said heat pipe.

3 more elements

Dependencies are inferred from the claim text.