High Altitude Automatic Welding Technology For Arch Ribs Of Steel Pipe Arch Bridges

In the construction process of the concrete-filled steel tube arch bridge,the arch rib is hoisted to the designated position by the arch rib segment and then connected by flanges and welds.The welding of the arch rib segment is basically completed in the high-altitude environment.It is more complicated,which has a certain i MPact on the efficiency and quality of welding engineering and the safety of workers.Pipeline all-position automatic welding technology is widely used in the petroleum pipeline industry,and the technology is mature.The welding of the arch ribs of the concrete-filled steel tube arch bridge and the welding of the petroleum pipeline have similar characteristics,that is,the weld has a high degree of uniformity(the shape of the weld fracture at different positions And the size is basically the same),so it is very feasible to apply the pipeline all-position automatic welding technology to the welding of the steel tube concrete arch bridge arch ribs,which can significantly improve the efficiency of the welding work,the quality stability and the safety of the staff;at the same time;The welding seam of the steel pipe arch rib has its own characteristics: the thickness of the welding seam is larger,the number of welding layers is larger,and the stability of the molten pool during the welding process is reduced due to the increase of the groove size.The inclination has different effects on the shape and quality of the weld.The thesis mainly studies the application of pipeline all-position welding technology to the girth welds of the arch ribs of concrete-filled steel tube arch bridges to realize the automation of the girth welds of the arch ribs.The main problems to be solved are:1.Simplify the design of welding parameters: propose a design method of welding parameters based on "heat per unit volume".2.The law of welding seam surface formation under different inclination angles and corresponding treatment methods: The welding seam surface formation is mainly affected by the stability of the molten pool.The experiment has selected 3 inclination angles of 0°,26.4° and 42.7°,at 0° and 26° inclination angles,The lateral forming of the weld has little effect;at an inclination of 42.7°,the lateral forming of the weld has obvious height differences.The corresponding processing method is to repair the lower part when the lateral height difference of the weld is approximately equal to the height of the weld layer,and then enter the next layer of welding.3.Selection of process interval: After Ansys analysis of the residual stress of steel pipe welding,the 6 interval process(half circle)is better than the 4 interval process as a whole.4.Unified management of welding data: A data management system has been compiled to uniformly manage welding robot welding parameters,weld forming pictures and finite element analysis results,which is helpful for the improvement and promotion of arch rib automatic welding technology.