Experimental study of temperature and clamping force during Nd:YAG laser butt welding

During welding, a high quality clamping device not only holds workpieces firmly together, but should also take the thermal strain of the welding heat without undermining the strength of the weld joint, inducing any excessive distortions, misalignment of workpieces or reducing the weld joint strength. This paper studies the clamping force during laser butt welding of steel workpieces. The clamping force and welding temperature for a butt welded joint during laser welding are measured simultaneously. The preset clamping force is varied during welding for different thicknesses of workpieces and weld joint strengths. The thermal expansion, cooling contraction, and workpiece width reduction during welding induce variations in the preset clamping force and consequently change the weld joint strength. Our study also reveals that there is an optimal preset clamping force that improves the weld joint strength significantly and the welding temperature during steady welding process remains unchanged for any preset clamping force. (C) 2009 Elsevier Ltd. All rights reserved.