Design Of Automatic Welding Assembly System For Reticulated Shell Steel Structure Joints

As people's aesthetic requirements for steel structure buildings are getting higher and higher,the shape of steel structure joints is becoming more and more complex,and the welded joint of special-shaped reticulated shell steel structure is one of them.The configuration of the steel joint is complex,the pose is different,the tooling positioning is difficult,and the current processing methods are mostly manual assembly and welding.There are problems such as low precision,low efficiency and many replacement tools,which lead to poor quality consistency of the joint and often cause the assembly of the node and the steel beam in the project.Therefore,this paper takes a kind of hexagonal corbel reticulated shell steel structure welding joint as the research object,designs a set of automatic flexible fixture for it,and integrates a set of steel joint automatic welding assembly system combined with welding robot application technology.Firstly,this paper analyzes the spatial structure characteristics and welding assembly process of a kind of hexagonal rectangular bracket reticulated shell joints,and proposes a design scheme of automatic welding assembly system for steel joints.According to the characteristic size and welding process requirements of steel joints,the welding robots,welding systems,positioners and other equipment are selected and designed.In order to realize the adjustment of flexible chemical tooling and automatic welding assembly,a set of flexible fixture and automatic feeding machine were designed,and the welding process planning,simulation and clamping experiment were carried out.Secondly,according to the spatial characteristics of the steel joints and the particularity of the assembly process,the basic requirements of the joint tooling are clarified,the design parameters of the flexible fixture are formulated,and the positioning and clamping scheme of the flexible fixture are proposed,thus forming the overall design scheme of the flexible fixture for the welding and assembly of the steel joints.Then the detailed structural design of each part of the fixture is carried out according to the design concept of combining modularization and automation.The dynamic simulation analysis of the fixture positioning module is carried out.The results show that the motion range and driving torque of each positioning module of the fixture meet the design requirements.Then,the three-dimensional layout and motion definition of the robot,welding gun and fixture are carried out,and the linkage between the displacement machine and the robot is realized by using the I/O signal control of the robot system,so as to build the virtual simulation environment of the automatic welding assembly system of the steel joints.The welding torch reachable range,welding posture and welding path of the robot are simulated,and the path test program is written to verify the rationality of the automatic welding assembly scheme of the steel joints.The interference situation of welding trajectory during robot arc welding is verified to ensure the rationality of system layout and path planning.The working rhythm of the system is estimated,and the results show that the welding efficiency of the welding robot is 30 % higher than that of manual welding.Finally,in order to verify whether the flexible fixture can meet the requirements of steel joint tooling,a flexible fixture test platform is built to test the adsorption capacity and positioning accuracy of the fixture,and the positioning error of the fixture is summarized and analyzed.The results show that the adsorption device can stably adsorb the web under various working conditions,and the maximum adsorption force can reach25 kg,which meets the adsorption requirements of steel joints in this project.The designed flexible fixture can make the total assembly deviation of steel joints less than3 mm,and the deviation of web spacing less than 2mm,meeting the assembly requirements of steel joints.The results of this paper can solve the problems of difficult positioning,more replacement tools and difficult deformation control of welded steel joints,improve the machining accuracy,production efficiency and production automation of steel joints,and provide technical reference for similar engineering applications.