Custom Beam Shaping for High-Power Fiber Laser Welding
Author: Victor, Brian M.
Degree: Master of Science, Ohio State University, Welding Engineering, 2009.
Committee / Advisors: Charles Albright PhD (Advisor) David Farson PhD (Committee Member)

Abstract

With the ever increasing power and performance of solid-state lasers, autogenous laser welding is becoming more practical for thick-section welding applications. High-power, high-beam-quality fiber lasers can produce high aspect ratio (depth/width) welds at productive travel speeds with minimal distortion. However, autogenous laser welding can produce undercutting or other geometric stress concentrations at the weld toes.

Through the design of custom optics, a laser beam can be directed to produce custom power distributions at the work, which can allow the fusion profile of a weld to be optimized for particular applications. By deflecting a portion of the laser power to trail the weld pool, the weld toes can be remelted to smooth stress concentrators and improve fatigue performance. This paper discusses the design and testing of a custom multi-spectral zinc sulfide beam shaping optic with a 10-kW IPG fiber laser.

In this research, laser welding parameters were developed for single-pass conventional welding. Feasibility trials were then conducted to prove the concept of smoothing the weld toes. To simulate the concept of a custom three-spot optic, three passes of a conventional optic were tested. Finally, a custom optic was designed and tested to evaluate welding and smoothing the weld toes with a single-pass solution. Weld toe angles in stainless steel were improved from 125 to 163 degrees by welding with the custom optic instead of conventional optics. Here's the link to the .pdf;

http://search.ohiolink.edu/etd/send-pdf.cgi/Victor%20Brian%20M.pdf?osu1238014676

Enjoy the reading... I know I will!!! :) :) :)

Respectfully,
Henry