Device for heating preform bodies or flat or preformed semi-finished products from thermoplastic material

An apparatus for heating preform bodies from thermoplastic material for use in blow forming, said apparatus comprising:

• at least one heat-supplying body (1.0, 2.0) having a surface that geometrically corresponds to an outer or inner contour of a preform body, said surface forming at least one first layer or coating (1.1, 2.1) and including a plurality of electrical heating resistors (5), each of said heating resistors in the form of a conductor loop arranged in a planar geometrical manner, each of said heating resistors individually controllable, each of said heating resistors having a temperature-dependent resistance, a thickness in the range of 1-10 μm and a width in the range of 0.001-5 mm, wherein
• said body (1.0, 2.0) includes contact elements and electrically conductive connections by means of vias in the at least one first layer or coating (1.1, 2.1) through which said heating resistors (5) are individually connected to a power source (1.2, 2.2) and a regulator, wherein the regulator is configured to determine the electrical resistance of the heating resistors, to derive temperatures based on the determined electrical resistances and the temperature-dependent resistances, and to individually control electrical power supplied to each one of said heating resistors based on the derived temperatures and a defined temperature profile, and wherein the geometrical arrangement of said heating resistors and the electrical power supplied to each one of said heating resistors are configured to generate the defined temperature profile;
• and
• an outer contact layer (1.3, 2.3) formed on the first layer or coating (1.1, 2.1) and configured to transfer the generated defined temperature profile to the preform body by contacting and transferring heat to the surface of the outer or inner contour of the preform body.