Abstract: In order to explore the ability of welding beads igniting polyurethane board (PUR), the ignition probability model of PUR was established based on the experimental platform of welding bead preparation and high-speed camera to record the whole process of bead formation to fall, and analyze the influence of welding bead diameter, kinetic energy and welding distance on its ignition ability. The results show that the particle size of the ignition molten beads is mostly concentrated in the range of 1 mm to 3 mm, and the particle size of the non-combustible molten beads is mainly distributed in the range of 0 mm to 2 mm. The critical kinetic energy of molten bead is 0.12×10-4 J. When the welding distance is determined, the igniting ability increases with the increase of current. When the loading current is constant, the igniting ability becomes weaker with the increase of the welding distance. Through the analysis of the above factors and the use of Logistic regression model, the ignition probability model of PUR is established. The verification shows that the prediction accuracy of this model is high, and the probability of ignition of PUR insulation materials by electric welding beads can be preliminarily predicted.

Key words: welding bead, insulation material, ignition probability, ignition capacity, polyurethane board