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US 3,947,204 AGranted
Scrapless forming of plastic articles
AssigneeThe Dow Chemical Company
InventorsRalph E. Ayres, Kenneth J. Cleereman, Walter J. Schrenk
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AssigneeThe Dow Chemical Company
InventorsRalph E. Ayres, Kenneth J. Cleereman, Walter J. Schrenk
Estimating the term…
Apparatus for rapidly making thermoplastic containers wherein the resultant containers can, if desired, be multilayered for vapor or gas barrier or other reasons, or be oriented for toughness and improved stress crack resistance. The apparatus takes a measured amount of thermoplastic material which is lubricated, heated and forged into a desired shape preform with a predetermined lip configuration. The center portion of each said preform is maintained at a forming temperature while the peripheral portion thereof is clamped and rapidly brought below the softening point of the plastic resin. The preform can then be immediately thermoformed into a container having a desired shape and size, and cooled. If desired, the preform can be forged, cooled and recovered for a subsequent thermoforming operation or can be a finished article itself.
An apparatus for scrapless forming of thermoplastic articles comprising a ring-like forming fixture adapted to receive a measured amount of thermoplastic material to be forged into a preform which can subsequently be thermoformed into an article, said forming fixture comprising an upper ring with a central oepning the lower extent of which defines a peripheral dimension about the same as that of said preform less its rim area, a lower ring including a central opening the upper extent of which defines a peripheral dimension about the same as that of said preform less its rim area, a lip opening contoured out of at least one of said rings around the entire extent thereof and presenting a face angled from the horizontal sufficient to resist the retraction stress of the thermoplastic material of the preform, the inner surfaces of said rings adjacent their respective central openings being spaced from one another a distance no greater than the thickness of said preform and presenting opposed shoulders which together with said face secure the peripheral rim area of said preform, including its lip, in clamped fashion within said fixture priior to and during subsequent thermoforming of the preform into a container, cooling channels extending through at least one of said rings adjacent the rim receiving portion thereof sufficient to cool rapidly the rim area while leaving the central portion of said proform at a thermoformable temperature.
An apparatus for scrapless forming of a thermoplastic article having a rim area with a finished molded lip, said apparatus comprising a ring-like forming fixture adapted to receive a measured amount of thermoplastic material to be forged into a preform which can subsequently be thermoformed into said article, said forming fixture comprising an upper ring with a central opening the lower extent of which defines a peripheral dimension about the same as that of said preform less its rim area, a lower ring including a central opening the upper extent of which defines a peripheral dimension about the same as that of said preform less its rim area, a lip opening contoured out of at least one of said rings at least partially about the extent thereof and presenting a lip opening angled from the horizontal to enable the preforms polymer when contained therein to resist the retraction stress of the thermoplastic material of the preform, the inner surfaces of said rings adjacent their respective central openings being spaced from one another a distance sufficiently close to the thickness of said preform to assist in resisting said retraction stress and presenting opposed shoulders which together with said lip secure the peripheral rim area of said preform in clamped fashion within said fixture prior to and during subsequent thermoforming of the preform in the event the preform is thermoformed into a container, at least one of said rings hving cooling means adjacent the rim receiving portion thereof sufficient to cool rapidly the rim area while leaving the central portion of said preform at a thermoformable temperature in the event subsequent thermoforming is desired without reheating.
An apparatus for scrapless forming of a thermoplastic article having a rim area with a finished molded lip, said apparatus comprising a forming fixture adapted to receive a measured amount of thermoplastic material to be forged into said article, said forming fixture comprisng a first clamp means with a centrral opening defining a peripheral dimension about the same as that of said article less its rim area, a second clamp means including a central opening defining a peripheral dimension about the same as that of said article less its rim area, a lip opening contoured out of at least one of said clamp means at least partially about the extent thereof, said lip opening including a cut-out presenting a face at an angle to the clamp means surface sufficient to enable the thermoplastic material of the article to resist the retraction stress of the thermoplastic material, inner surfaces of said clamp means adjacent their respective central openings being spaced form one another a distance sufficiently close to the thickness of said article to assist in resisting said retraction stress and presenting opposed shoulders which together with said lip opening secure the peripheral rim area of said article in clamped fashion within said fixture.
Dependencies are inferred from the claim text.