A Theoretical And Experimental Study On Keyhole Effects In Laser Deep Penetration Welding

The keyhole effects in deep-penetration laser welding of GG17 (Pyrex) glass are theoretically and experimentally studied in this paper. First of all, the LASERSCOPE UFF100, a diagnostic instrument for the measurement and monitoring of high-power material process lasers, is used to measure beam width, divergence angle and beam propagation factor. At the same time, a keyhole can be clearly observed by a high-speed camera while welding and a technique of laser welding glass GG17 (Pyrex) was developed to get clear photographs of the keyhole for quantitative study. Secondly, a theory model for only considering simple conduction and a mathematic model for taking into account both conduction and convection in the welding pool are generally built. Both two types of models are calculated and compared with Finite Difference Method (FDM) and Finite Element Method (FEM) separately. Finally, according to the results of calculating two types of models and the datas obtained from the deep-penetration laser welding experiments of GG17 glass, the effects of such parameters as the size of focal spot, focal position and welding speed on the shape and size of the keyhole are investigated.