| 摘要 |
This relates to the thermoforming of can bodies for use in packaging beverages under pressure from polyester sheet material, preferably PET. In accordance with the invention, a forming gas is applied to the periphery of the clamped sheet portion in radially outwardly spaced relation with respect to an associated mold cavity and the sheet material is billowed up into a large cavity formed in the clamp so as to provide for high stretching and orientation of the peripheral portion of the sheet before the sheet is directed into an associated mold cavity. Further, a plunger which normally forces the billowed or initially stretched sheet into the mold cavity may be constructed so as to be radially expandible to thus positively radially expand the sheet material within the mold. The operation of the molding apparatus is one wherein the periphery of the sheet material from which the cup is formed has a much greater biaxial orientation than heretofore possible, and therefore the resultant can body is much stronger than that previously feasible with the same material. This abstract forms no part of the specification of this application and is not to be construed as limiting the claims of the application.
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