Closed cell foam plastic molding machine

Details Closed cell foam plastic molding machine Closed cell foam plastic molding machine

1976-03-22

1977-06-14

Lazarus, Richard B.

Plastic article or earthenware shaping or treating: apparatus

Control means responsive to or actuated by means sensing or...

Feed control of material en route to shaping area

264329, 264DIG83, 425244, 425817R, B29F 106

Patent

active

RE0292656

ABSTRACT:
Plastic molding machine, primarily adapted for generating and molding a closed-cell foam plastic material. The foam is generated by introducing a gas inert to the plastic material into a granular mixture of same so that the gas is thoroughly intermixed among the granular particles. The gas is then held under pressure while the granular particles are reduced to a flowable material, said pressure being sufficient to assure that the gas will not be expelled therefrom during the plasticization process. In one preferred embodiment, gas is mixed into the granular plastic in a hopper and held therein under pressure as said granular material is fed into a screw and plasticized thereby.
The plastic material is then conducted at a relatively low pressure, such as that generated by the extrusion machine used for plasticizing the material, through a branched system past a check valve in each branch of said system, to an injection assembly. As each injection assembly receives a predetermined amount of plastic material, means are energized preventing more plastic material from entering thereinto but continued operation of the pressure generating device will continue filling other injection assemblies for as long as any thereof are capable of receiving such material. When all injection assemblies are filled, same are actuated simultaneously to drive the plastic material therefrom into the mold cavity. Injection assemblies may supply mold cavities in any pattern, and a single mold cavity may be associated with a given injection assembly or two or more injection assemblies may supply any one given mold cavity.
Local zones, preferably subjected to rapid cooling, are provided with undercut notches connected to the sprue, runners or cavity and filled thereby with plastic. Same is cooled ahead of the cooling of the molded part and provides means for holding the mold closed. This permits removal of the mold from the machine prior to cooling of the molded part and opening of the mold which in turn permits more effective use of multiple molds with a given machine.

REFERENCES:
patent: 2892214 (1959-06-01), McCarthy
patent: 3353209 (1967-11-01), Schad
patent: 3436446 (1969-04-01), Angell, Jr.
patent: 3543348 (1970-12-01), Nussbaum
patent: 3674401 (1972-07-01), Annis, Jr. et al.

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