Research And Development Of CNC System For Welding Torch Pose Control In Saddle-shaped Seam Welding

The saddle-shaped seam welding is one of the most common and important tasks in the welding of spatial intersected curves, which exists widely in nuclear, military, automotive, shipbuilding, and valve manufacturing industries. The research on the automatic welding control based on CNC technology for the saddle-shaped curve has very important significance in improving the control precision of welding trajectory and improving the welding quality and efficiency.Based on the domestic need for the automated welding technique of complex special welding seam, this thesis deeply researches on trajectory control, welding torch pose control and welding specification control in the process of automated saddle-shaped seam welding. The main contents and results are as follows:The thesis analyzes the characteristics of welding torch pose control in the saddle-shaped curve automatic welding system, and researches on the basic structure, control parameters and welding process of the saddle-shaped seam welding CNC system.In this thesis, the saddle-shaped curve direct interpolation algorithm is studied and proposed. Based on system kinematics analysis and the principle of the space analytic geometry, this thesis establishes the trajectory model, the welding gun pose model and speed control model; and proposes two interpolation algorithms for saddle-shaped curve automated welding. It also compares and analyzes the characteristics of these two direct interpolation algorithms. It chooses the interpolation algorithm, which is based on welding torch pose control and speed control, as the direct interpolation algorithm for the CNC system. This algorithm not only has a high trajectory accuracy and pose accuracy, but also has good feed rate controllability; in order to ensure the welding trajectory and welding specification.An IPC-based CNC system for automated welding of saddle-shaped curve is developed, including the hardware and software system. The CNC system is designed based on the characteristics of saddle-shaped curve and welding process requirement. Also the servo drive system interface is designed. An OpenGL-based dynamic graphic simulation is also realized.