Research On Key Technologies Of Saddle-shaped Weld Welding Machine CNC System Based On Pmac

Welding of intersecting welds is widespread in the oil,chemical,nuclear and other industries.As China's backward in the development of automated welding technology,saddle-shaped weld welding equipment is at a low degree of automation so that it is difficult to meet the requirements.At present,the welding of intersecting welds is still based on handwork welding,and there is a problem that the welding efficiency is low and the welding quality is not easy to be guaranteed.Therefore,in this thesis,a set of saddle weld welding machine CNC system is developed based on the PMAC motion controller,and the key technologies such as saddle-shaped curve interpolation algorithm and multi-path/multi-layer welding path planning are researched deeply.According to the characteristics of PMAC motion controller,the hardware structure and software system of NC system based on "IPC + PMAC" are built.Based on the modular design concept a numerical control system management software is developed to achieve a friendly human-computer interaction by using Visual C++ programming language.In order to solve the complicated situation of workpiece deformation and installation error in intersecting line welding,a trajectory planning strategy combining saddle-shaped curve direct interpolation and online teaching mode is proposed.The mathematical model of the saddle curve is established,and the direct interpolation algorithm of the saddle curve is deduced.The simulation results show that the interpolation algorithm has high interpolation precision.Aiming at the problem of low interpolation accuracy and poor welding quality in the teaching planning,a universal constant-speed uniform B-line interpolation algorithm is proposed,and the MATLAB simulation results show that the interpolation algorithm is reasonable and feasible.In this thesis,a multi-path/multi-layer welding path planning strategy for saddle-shaped welds is proposed,which realizes the continuous automatic welding of saddle-shaped welds.And the rationality of the strategy is verified by simulation.In order to improve the welding quality,the influence of different welding sequence on the welding deformation and residual stress in the same layer is studied by numerical simulationmethod.Through the comparison and analysis of the simulation results,the optimal welding path planning sequence is obtained.