Research On P-GMAW All-position Pipeline Automatic Welding System

Due to the unbalanced distribution of oil and gas resources in China,a large number of pipelines need to be built for oil and gas transportation.At present,the welding rod arc welding and semi-automatic welding are mostly used in the pipeline construction,and the full position pipeline automatic welding technology is relatively less used.However,the pipeline automatic welding technology has the advantages of high welding efficiency,good weld formation and high welding quality,so the oil and gas pipeline is gradually laid Automatic welding technology is used to replace manual welding and semi-automatic welding.Therefore,in order to improve the production efficiency and weld forming quality of oil and gas pipeline welding,it is necessary to develop all position pipeline automatic welding system with compact structure,light weight and high stability to meet the current demand of oil and gas pipeline laying.Firstly,based on the analysis of all position pipeline automatic welding system at home and abroad,aiming at the functional requirements and field requirements of the pipeline automatic welding system,the overall scheme of the pipeline automatic welding system is designed,and STM32 is selected as the main control chip of the system.Secondly,the mechanical structure of the welding trolley device,the lateral swing device,the longitudinal lifting device and the track device supporting the welding trolley in the pipeline automatic welding system are designed respectively,and the selection of stepper motor,servo motor,matching driver and ball screw is completed.In order to make the welding trolley walk stably on the pipeline,a PID closed-loop control algorithm is designed for the AC servo motor driving the welding trolley.The S-type acceleration and deceleration algorithm is designed for the stepper motor driving the welding torch swing,which greatly reduces the impact on the mechanical system when the welding gun swings to the displacement direction of the left and right wall positions.The software and hardware of the remote controller and the main controller module in the pipeline automatic welding system are designed.In order to meet the welding process requirements of different pipe groove and weld bead,four kinds of welding torch trajectory control programs are designed.Through programming,the welding process parameters such as welding torch swing speed,swing amplitude,welding current and other welding process parameters are adjusted,manual deviation correction,automatic deviation correction,welding gun lifting control and welding power communication control are realized.In this paper,STM32 and ad7606 are used to establish the welding arc electric signal acquisition and processing unit.The hardware interface circuit of STM32 and ad7606 is designed,and the data acquisition and processing program is compiled.The real-time synchronous acquisition and processing of welding arc electric signal is realized.Finally,the pipeline welding test is carried out by using the designed P-GMAW all position automatic welding system,and the all position thin-layer multi pass and downward welding method is adopted.The test results show that the seam forming is good in different positions and weld passes,the welding quality is stable,and the whole system runs smoothly,which verifies the effectiveness and reliability of the designed pipeline automatic system.