Method and apparatus for infrared welding of thermoplastic parts

Apparatus for joining thermoplastically weldable materials using infrared radiation to create a weld area comprising:

• an energy source for producing radiation in the infrared band;
• and
• a radiation-directing structure for directing radiation from the source to an area to be welded;
• said structure including,
• (a) a first reflector which at least in one cross-sectional plane is parabolic and has a focus;
• and
• (b) a second reflector joined substantially end to end and optically continuous with the first reflector and having, at least in said cross-sectional plane, a non-imaging shape and an outlet at an end remote from the first reflector and of a configuration which substantially corresponds to the desired configuration of the weld area;
• said source being essentially located at said focus whereby radiation from the source is collimated by the first reflector and wherein the radiation from the source collimated by the first reflector is directed to the outlet without significantly reflecting back toward the source.

A method of thermally joining thermoplastically weldable materials in an abutting or layered relationship comprising the steps of:

• providing a source of infrared radiation;
• collimating the radiation from the source using a first reflector the reflective interior portions of which are parabolic in at least one cross-sectional plane;
• and
• directing the radiation toward the layered thermoplastically weldable materials to be welded using a second reflector the reflective interior surface or surfaces of which are optically continuous and essentially contiguous with the reflective interior portions of the first reflector wherein the radiation reflected by the first reflector is directed to the outlet in the directing step without significantly reflecting back toward the source.

A method of joining overlying materials by means of a weld joint of defined shape between the materials comprising the steps of:

• layering two materials;
• providing a source of infrared radiation;
• collimating the radiation from the source using a first reflector the reflective interior surface or surfaces of which are parabolic in at least one cross-sectional plane;
• and
• directing the collimated radiation toward the desired weld joint of the overlying materials using a second reflector the reflective interior surface or surfaces of which are optically continuous and essentially contiguous with the reflective interior surface or surfaces of the first parabolic reflector and which further defines an outlet corresponding to the defined shape through which the radiation is directed toward the weld area wherein the collimated radiation is directed to the outlet in the directing step without significantly reflecting back toward the source.