Method for heating and controlling temperature of composite material during automated placement

Abstract

Composite articles are produced by guiding composite tape material through a compaction region where the tape material is pressed onto a substrate, and heating the tape and substrate ahead of the compaction region by irradiating opposing surfaces of the tape and substrate with laser radiation produced by a laser diode array. The laser diode array is divided into independently controllable diode groups, and the diode groups are controlled so as to independently control heating of one area of the tape and substrate relative to another area of the tape and substrate. In one embodiment, the widthwise profile of the light energy is such that a widthwise portion of the tape at an inner radius of a curved path along which the tape is steered at the compaction region is heated to a greater extent than a widthwise portion of the tape at an outer radius of the path. The laser diode array can also be controlled to heat the tape material to a different extent than the substrate to compensate for different rates of heat loss. One or more diode groups of the array can be deactivated when not needed, such as when the tape material is narrower than the full light field generated by the array. Different diode groups of the array can produce light of different wavelengths for achieving different rates of absorption by different areas of the composite materials.