SBIR-STTR Award

Effective implementation of laser welding in shipbuilding is hampered by a number of issues: large capital equipment investments, multi-faceted robotic control issues, lack of effective weld cell concepts and the lack of intelligent optics for laser process control. This project proposes to develop a process and an intelligent optics for laser welding that allows thick section welding in multiple paths. Multiple path welding drastically decreases the required laser power and allows the use of more cost effective standard laser systems. The developed intelligent optic incorporates seam tracking, closed looped with beam steering to adjust the laser beam to the joint requirements of the respective path. It is also easy to integrate into the robot cell. Necessary steps will be identified to adapt the intelligent optic to the requirements for appropriate joint design, fixturing, weld cell design for shipbuilding structures, and off-line programming features needed for effective integration into a large volume, non-standard welding application.

Benefits:
Visotek?s laser welding optics is a highly integrated product that fits on almost every robot. If offers seam tracking closed looped with beam steering, simplified clamping, the possibility for on-line quality monitoring and sophisticated interfaces that allow the user to comply with high quality standards. The intelligent integrated optic created in the I-Low program will be an enabler to the use of laser welding for shipbuilding and will lead other equipment manufacturers that use thick section materials to increasingly seek ways to expand the use of lasers in the design of future products. The construction, mining, power generation and pipeline industries will be targeted for new applications of lasers utilizing the developed optic. In addition, expanded uses within the automotive and the military and commercial aerospace industries are also anticipated. This open ended capability to serve a variety of fields will create an opportunity to compile, document, package and make available integrated laser welding optics to countless non-competitive industries. The total market volume is close to $30 million annually.

Keywords:
laser welding,seam tracking,beam steering,welding optics,robotics,close loop control

Visotek’s Phase I work on 'Affordability of Shipbuilding Technology' was focused on investigating the difference between multiple path welding and weave welding applied to stake joints and T-joints in a fillet weld configuration. A special optic was designed and built for an Nd:YAG laser to be used on thin section material of 1/8" thickness. Weld tests were performed and a sandwich panel was welded using Bender Shipbuilding’s unique tab & slot design. It was demonstrated that the weave weld enabled full fusion at the interface of stake welds. The feasibility demonstrated in the Phase I work created the interest for rapid implementation into the shipyard at Bender. In Phase II, the integrated optic will be adapted to high power CO2 lasers. The functionality will be enhanced by increasing the weaving frequency, the controllability, and full 2D weld line capability. The process parameter window will be developed. Two integrated optics will be installed for test and production in the field. The standards for autogenous laser welding currently being developed in other programs will be adapted to the stake weld. On-line quality monitoring, seam tracking and gap mitigation procedures will be developed. Benefit The commercial applications for this new technology will initially benefit the American shipbuilding industry by introducing laser welding as an affordable technique for the production of high quality products. The prototypes will enable the first laser welding installation in a U.S. shipyard and will set an example for other shipyards to follow. The scope of applications becomes wider when the I-LOW optic has been designed to interface with both Nd: YAG and CO2 lasers. The concept of the optics will be applicable to any industry that is currently using laser welding for joining metal structures. Most of the world’s automotive manufacturers are moving towards laser welding, replacing conventional and spot welding systems. The I-LOW optic provides a tool for applying a higher quality weld and reducing defect rates. In the thin metals arena there are a number of other players, including appliance manufacturers, electrical and electronic components manufacturers, metal furniture, HVAC, heavy manufacturing systems and the aircraft industry. Keywords Optics, T-Joints, Weave welding, sandwich panels, Autogenous welding, Stake weld, laser welding, CO2 laser