Research On Path Planning And Welding Process Of Large Box Girder Double Robots Welding Torch

Welding of steel structures is indispensable in the production of aerospace,mechanical transportation,bridge construction and military industries.In recent years,the demand for port container cranes in various countries has increased,which puts forward higher requirements for the welding efficiency of the medium and thick plates inside the box.The traditional box body connection method uses manual welding,which has problems such as low production efficiency and unstable quality.For the welding of the medium-thick plates inside the box body,there is an urgent need for an automated welding method with a mature production process to solve the above problems.Therefore,this paper proposes a high-efficiency welding method for the T-joint of medium and thick plates,First,by building an automatic welding system with dual robots inside the box,plan the welding path of the dual robots inside the box girder.At the same time,double-sided double-arc welding with double robots is used to realize full penetration and unclear root welding of T-joints.Finally,research the automatic horizontal welding process of the T-joint of the medium and thick plates,explore the influence of relevant parameters on the test results,provide certain theoretical support for better realization of automated production.In the study,first established a large box girder model,discussed the conversion and extraction of box model files,and discussed the general method of robot path planning by building a guide rail gantry platform.At the same time,combined with engineering reality,plan a practical box welding path for engineering applications,use offline programming and simulation modules to verify the robot welding path,and finally realize the production of box beams in the workshop.Using numerical simulation software MARC study the evolution law of the angular deformation and residual stress of the test plate after welding at different arc spacing,the results show that: when the arc spacing is 0-20 mm,the deformation of the partition along the X direction gradually increases;when the arc spacing is 30-40 mm,the deformation of the partition along the X direction gradually decreases and tends to be stable;When the double-arc synchronous welding,the deformation of the lower wing plate is the largest,when the arc distance is 20-30 mm,the deformation of the lower wing plate tends to be stable.In the experiment,the welding sequence of the T-joint was first studied,by comparing the temperature changes in the fusion zone and the residual stress in different welding schemes,the results showed that when the double-arc synchronous welding from the arc starting point to the arc extinguishing point,t8/5 is in a moderate time frame,the residual stress and the deformation of the base metal after welding are the smallest;Then in order to make the root of the weld be fully penetrated,realize single-sided welding and double-sided forming,pre-research test by adjusting the process parameters of the front arc welding torch the results show that the test can achieve full penetration and unclear root welding at the root of the T-joint K-shaped symmetric groove,and the shape is good after welding,without cracks,pores,impurities and other defects.The microstructure of the arc welding bead before the primer is mainly acicular ferrite and a small amount of lower bainite,and the microstructure of the arc welding bead after the primer is mainly pearlite and proeutectoid ferrite.there is no wisdom organization in the heat-affected zone;The average hardness value of the joint weld is 230 HV,which is higher than the average hardness of the base material of 180 HV.The maximum impact absorption energy near the fusion line after welding is 231 J,and the minimum impact absorption energy at the center of the weld is 105 J,both of which meet the "American Steel Structure Welding Specification" required 27 J.