US 4,755,129 AGranted

Trim in place thermoforming arrangement for plastic articles

AssigneeMobil Oil Corporation

InventorsPhilip S. Baker, Roland De May, Stephen L. Goulette, Jonathan Gross

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Abstract

An arrangement for the thermoforming of molded plastic articles from a continuous web of a thermoplastic material, and more particularly, a trim in place thermoforming arrangement in which the plastic articles are simultaneously molded and at least substantially or completely separated from the remaining thermoplastic web material. A high degree of alignment and precision is obtained between cooperating cutting blades employed in the trimming of the thermoformed articles, because of a unique self-aligning or floating support structure of at least one of the cutting blades operating in conjunction with the thermoforming apparatus. The self-aligning action provided for between the slidingly contacting cutting blades allows for an automatic compensation for any temperature changes and blade wear encountered during operation, and with only one movable part being required for the trim in place device.

Claims4

Dependent claims

A trim in place thermoforming arrangement for the sequential molding and trimming of plastic articles from a generally continuous sheet of thermoplastic sheet material;

comprising a thermoforming die assembly having male molding die means and complementary female molding die means reciprocatable towards and away from each other and having surface portions defining an article molding contour therebetween;
said thermoplastic sheet material being postionable intermediate said male and female molding means for thermoforming said sheet material into molded articles;
and first and second mutually self-alignable cutting means mounted on, respectively, said male and female molding die means coacting to at least substanitally separate the molded articles from said sheet material, said first cutting means comprising an annular upwardly extending cutting blade fixedly supported in annular recess formed in said male molding die means, and said second cutting means being an annular downwardly depending cutting blade movably supported in an annular recess formed in said female molding die means so as to be radially displaceable and engageable in a self-aligning interference fit with said upwardly extending cutting blade during the closing movement of said male and female molding die means.

Dependencies are inferred from the claim text.