The Study Of Robot Welding Trajectory Accessibility For TBM Parts

Tunnel boring machine(TBM)is widely used in subway,railway,highway,municipal,hydropower and other tunneling projects as a tunnel boring special engineering machinery.In the manufacturing process of TBM,the welding workload is huge,the working time is long and it has a high quality standard.At present,manual welding is widely used in TBM manufacturers.It has a low production efficiency and it’s difficult to guarantee the consistency of welding quality.It’s imperative to realize the automation of TBM.Because of the feature non-standard custom,it brought difficulty to the development of workstation.The article starts with the reachability of welding track,and puts forward a method to optimize the commonality of welding station.Meantime,a seam tracking system was developed to improve the welding quality.The first part analyzed the impact of workpiece placement on trajectory accessibility.For the workstation structure of cooperation between the robot and the positioner,we can get the accessible area by calculating the work envelope of the robot with fixed posture torch.By calculating the effective working envelope,we can get the best relative position between robot and positioner.The second part analyzed the impact of workpiece structure on trajectory accessibility.When the workpiece structure is more complicated,we can’t judge the accessibility only by the position of the seam.The workpiece structure will also affect the reachability of the torch.By comparing the reachability level of each workpiece between the original structure and the optimized structure,it is proved that the optimized structure can meet welding requirement of most workpieces.The optimization effect is remarkable.We analyzed the effect of the workpiece structure on the workstation structure,and put forward further suggestions of structure adjustment,including replacing torch and adding another external axle for robot height adjustment.The new workstation can meet reachability of all workpieces.For the problem that the welding torch deviates from the welding track duo to the welding deformation during multilayer welding process,human-machine interactive real time control strategy was put forward and the controlling system was developed.The HMI is based on the development of the.Net platform.The image of the welding area is obtained through the camera to determine the direction of the welding gun offset and whether it needs to be adjusted.The control system takes the PLC as the control core,and sends the correction instruction through the RSI interface.The system realized the real-time adjustment of the torch position.The control precision of control system is 0.1 mm,which can meet the needs of welding.It is proved by the welding experiment that the control system can meet the requirements of multi-layer multi-channel welding seam tracking.