A Mathematical Model of the Auto-Repair Welding System for the Large-Scale Pressure Vessel’s Hemispherical Head

A mathematical model of the auto-repair welding system for the pressure vessel’s hemispherical head is proposed according to the principles of the robotics. The welding system can be simplified to a four-axis linkage system and two types of models can be obtained. Using these mathematical models, we analyze the position of the welding torch and derive the velocity formulas of the four axes in the system. All these formulas can be used in the development of the auto-repair welding system. The welding of the transition section which is mainly discussed in this paper is complex in the whole repair process, and a geometry model is proposed for it. The auto-repair welding experiments have been given to illustrate the validity of this model.