Sheet perforation apparatus with heated needles and a complementary mold

A method for shaping perforations in thermoplastic sheet material having a planar surface, comprising:

• (a) penetrating the thermoplastic sheet material with a needle attached to a first mold structure, said needle being located above the planar surface and comprising a cylindrical portion having an upper end and said needle being adapted to penetrate the thermoplastic sheet material wherein said first mold structure is defined by an outwardly disposed part circular portion near said upper end of said needle;
• (b) contacting the needle with a complementary mold structure positioned below the planar surface wherein both of said first and complementary mold structures are arranged to be reciprocated;
• and
• (c) moving a central portion of at least one of the first and complementary mold structures in an opposite direction to a peripheral portion of the at least one of the first and complementary mold structures to produce a substantially smooth half-circular section bead on the peripheral surface of the perforation.

A method for shaping perforations in thermoplastic sheet material having a planar surface, comprising:

• (a) penetrating the thermoplastic sheet material with a needle attached to a first mold structure, said needle being located above the planar surface, said needle being adapted to penetrate the thermoplastic sheet material;
• (b) contacting the needle with a complementary mold structure positioned below the planar surface, wherein both of said first and complementary mold structures are arranged to be reciprocated;
• and
• (c) moving the first and complementary mold structures in the same directions to produce a perforation in the thermoplastic sheet material.