Branson Ultrasonics Corporation

Paul A Rooney

Scott Caldwell

David A Grewell

Donald C Lovett

Justin R Bickford

Unabsorbed infrared laser light that has passed though plastic parts to be welded with a low absorption TTIr process is recirculated in an infinite loop back to the low absorption weld interface for reabsorption in the process. On each pass in the infinite loop, more infrared laser light is absorbed at the weld interface.

Infrared plastic welding with recirculation of unabsorbed infrared laser light to increase absorption of infrared laser light

Unabsorbed infrared laser light that has passed though plastic parts to be welded with a low absorption TTIr process is recirculated back to the low absorption weld interface for reabsorption in the process. A beam of infrared laser light is directed at the plastic parts to be welded, a transmissive first part and an absorptive (or partially absorptive) second part. The infrared laser light impinges the transmissive part and first transits through the transmissive part to be welded to a weld interface at the junction of the two parts. At the weld interface, either the infrared laser light is partially absorbed by an additive infrared absorber, the infrared laser light is partially absorbed by the absorptive part, or both. The portion of the infrared laser light that is not absorbed continues through the absorptive part and exits the far side. This infrared laser light is then redirected back to the weld interface.

The present invention is directed to a method and apparatus using a light guide for directing a laser beam to a weld zone. The light guide includes an entrance end, an exit end and a flexible body therebetween. The entrance end of the light guide is operatively coupled to a laser source such as a diode and is adapted to receive and communicate the laser radiation through the light guide. The light guide is formed of a flexible material to permit the exit end of the light guide to be spaced from and aligned with complex two-dimensional and three-dimensional weld zone configurations. The internal reflection of the light guide contains the laser radiation therein as it passes from the entrance end and through the exit end of the light guide. The light guide and corresponding methods of welding parts permit laser welding of complex geometric configurations.

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Rochester, NY, United States of America

Paul A Rooney