Method of heating by emission of electromagnetic radiation, especially infrared radiation

A method of joining non-sheet therrmoplastic parts having joint lines of non-planar complex profile, comprising the steps:

• locating a resistive element in proximate conforming relation to the joint lines;
• forming a conforming channel of concave surface in spaced proximity along the length of the element;
• coating the concave conforming surface with a reflective material;
• providing the element with current to generate radiation reflected from the reflective material toward at least one of the joint lines;
• subjecting the joint line to the radiation to cause its melting;
• removing the element from the channel;
• fusing the parts together along the melted joint lines;
• wherein the joint line profile is copied to form a channel, and further comprising the steps:
• machining a polymer resin to obtain an impression whose profile is substantially identical to that of the joint lines;
• filling the impression with an alloy having a melting point within the range 50.degree.-200.degree.;
• depositing a thin nickel based film onto a free surface of the impression after solidification of the alloy;
• machining a plurality of slots in the alloy to form emission zones;
• positioning the element along the length of the impression;
• rigidifying the element by filling the impression with refractory material;
• placing the resulting assembly in an environment having a temperature slightly greater than the melting point of the alloy.

A method of joining non-sheet thermoplastic parts having joint lines of non-planar complex profile, comprising the steps:

• locating a resistive element in proximate conforming relation to the joint lines;
• forming a conforming channel of concave surface in spaced proximity along the length of the element;
• coating the concave conforming surface with a reflective material;
• providing the element with current to generate radiation reflected from the reflective material toward at least one of the joint lines;
• subjecting the joint line to the radiation to cause its melting;
• removing the element from the channel;
• fusing the parts together along the melted joint lines;
• wherein the joint line profile is copied to form a channel, and further comprising the steps:
• shaping an elastomeric flexible cord in conformance with the geometry of the joint line;
• embedding the shaped cord in a bed of refractory and binder material;
• backing the embedded cord with a planar reinforcement;
• solidifying the resulting assembly;
• removing the cord;
• replacing the cord with the element.