Dependence of Dowel Joint Strength on Welding Temperature in Rotary Welding

The system for measuring the welding temperature with measuring probes has been developed for the requirements of this but also of future research (at the Faculty of Forestry and Wood Technology, University of Zagreb). The research is based on determining the welding temperature and its impact on the joint strength or the embedded force of the dowel. Based on research results, the impact of the dowel rotation frequency and temperature on the joint strength has been determined. The measured welding temperature increased as the rotation frequency increased (the rotation frequencies of 865 min-1 and 1520 min-1 were used in the research). The maximum welding temperature in pine samples welded at the rotation frequency of 1520 min-1 amounts to 217 °C, while in samples welded at the rotation frequency of 865 min-1 it amounts to 179 °C (weld penetration of 20 mm). The maximum welding temperature in beech samples welded at the rotation frequency of 865 min-1 amounts to 181 °C, and 213 °C at the rotation frequency of 1520 min-1 (weld penetration of 20 mm). The impact of the wood type on the welding temperature has not been proven. In order to avoid difficulties encountered in contact measurement of the welding temperature, a heat transfer model was developed for a more precise determination of the welding temperature.