Thermoforming process and apparatus
AssigneeInternational Container Corp.
InventorSteven F. Manlove
Life of this patent
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Abstract
This invention is an improved thermoforming process and apparatus for the production of rigid plastic containers. The apparatus employs a molten sheet of thermoplastic material that is processed through two extrusion rolls, thermoformed on the periphery of a rotating form tool, mechanically ejected from the form tool conveyed to a conventional punch press where the formed articles are trimmed from the sheet then packaged for shipment. The operation of the extruder, extrusion rolls, forming wheel, mechanical ejection and trim stations are operated as a continuous, integrated system.
Claims1
Apparatus for thermoforming rigid thermoplastic articles comprising:
- a sheet extrusion die for extruding a sheet of thermoplastic said extrusion die being oriented on a 45 degree angle from the vertical and held at a fixed elevation;
- a set of extrusion rolls each adapted to rotate about an axis so as to feed the extruded sheet down and away from the extrusion die, each axis of said extrusion rolls lying within a plane that is approximately 45 degrees from the vertical and perpendicular to the extrusion die;
- a forming wheel comprised of a plurality of mold facets, said mold facet containing at least one mold cavity;
- means for rotating said forming wheel about a horizontal axis so that each said mold facet is moved through sectors dedicated to forming said sheet into said articles and ejecting said articles, said horizontal axis lying below and parallel to said plane defined by said extrusion roll axes;
- a thermoforming assist plug wherein said assist plug is arranged over said forming sector of said forming wheel;
- means for synchronizing movement of said thermoforming assist plug with the movement of said molding facets as said forming wheel rotates;
- means for actuating said thermoforming assist plug into said thermoplastic sheet and said mold cavity;
- means for evacuation of air from within said mold cavity thereby forming an article associated with each said mold cavity wherein portions of said sheet remain unformed;
- a machine frame being configured to permit th use of alternate diameter forming wheels while said extrusion die is held at said 45 degree angle and fixed elevation;
- said machine frame having a platform that is set parallel to said plane defined by said extrusion rolls, said machine frame platform holding an axle located on said horizontal axis about which said forming wheel rotates;
- said mold facets being comprised of a static upper mold facet section and a dynamic lower mold facet section;
- said dynamic lower mold facet section containing said mold cavity;
- said static and dynamic mold facet sections support circuits for circulating a temperature control medium and vacuum;
- a stationary ejection shoe;
- and
- a guide rod assembly including a means for actuating and guiding movement of said dynamic lower mold facet section towards said forming wheel axle when the means for actuating and guiding comes into contact with said stationary election shoe during rotation of said forming wheel.
Dependencies are inferred from the claim text.