Influence of the Depth of Friction-welded Dowels on the Strength of Rotary Welded Joints

Abstract

One of the important factors in rotary welding is the depth of welding of the dowel as well as the direction of welding of the dowel. In the studied interval (welding depth of 15 to 30 mm), the pull-out force increased when welding the dowel parallel to the wood grain and perpendicular to the wood grain. The strength of the welded joint increased from 15 to 20 mm, and then it continuously decreased towards a welding depth of 30 mm. The reason for this is that the tip of the dowel is intensively worn, and with a welding depth of 20 mm, it is approximately equal to the diameter of the hole. Therefore, by increasing the welding depth, the pull-out force increases slightly (due to the friction between the dowel and the hole wall), and the strength of the joint decreases. The highest joint strength was achieved at a welding depth of 20 mm for specimens welded parallel to the grain (PV) and specimens welded perpendicular to the grain (RTV). In welded joints where the dowels are loaded only by tensile force, it is recommended to use a welding depth of 30 mm.