Study On Human Welder Behavior By Measuring Local Flow Pattern Of Weld Pool And Torch Posture

In recent years,with the rapid development of welding in extreme environment,for example,all-position welding of pipeline in deep sea resources development,the welding of confined space components in nuclear equipment and weightlessness environment,lower limit of vacuum space station,the welding quality requirements are getting higher and higher.On the other hand,the risk factor is extremely high during welding,and it is difficult for welders to do manual operation on the spot.However,in present,the research of artificial intelligence,welding environment identification and problem planning is it doesn't go far enough,the robot can not be separated from the welder in a strange environment and do the welding work autonomously.So the urgent need for a new generation of intelligent robot for welding operation like skilled welders.In order to solve the difficult problem,we find the weld pool surface carrying characterization of much information of welding quality,weld forming,for example weld penetration,weld width.So as to control the weld pool stably with welding robots like skilled welders,we need to analyze the human welder behavior and transplant the behavior into the welding robot.Therefore,measuring welding pool surface experimental data is used to investigate the physical change behavior of the weld pool,to improve the welding quality and accelerate the intelligent welding robot research has very important theoretical significance and application value.In this paper,the method of laser vision is adopted for the principle that the reflection of light is different from the surface of weld pool and material,and studied the dynamic welder behavior in following aspects:(1)According to the measurement principle of laser vision method,welding torch,laser,imaging screen and welding torch posture sensor fixture was signed.We established a laser vision with welding torch posture sensing system.An experimental platform for measuring the experimental data of the weld pool surface has been built.And the measurement of the dynamic change of the weld pool surface has been realized.(2)We achieve the laser stripe images are reflected by the weld surface,the brightness of laser stripe on imaging screen is solved by using designed algorithm.Through comparative analysis of the concentration change of laser stripe on the imaging screen in single adjustment,such as welding speed,welding current,arc length,welding torch posture.We found that Single adjust welding parameter,the stability of the weld pool and the weld formation is poor,the brightness of the reflected laser stripe change greatly.Compared with welder adjust welding torch posture,the welding torch posture adjustment is easy to make the weld pool reach a stable state,and weld formation is good,the brightness of laser stripe change on imaging screen is small.The experiment result shows that abundant welding skills and welding experience are required for better weld formation.(3)In order to explain the change of weld penetration in welding process,the different state aggregation of laser stripes reflected from the weld pool surface on imaging screen.The effect of welding current and arc length on penetration is simulated and calculated.The result shows that the mathematical model established can reflect the action process on penetration of welding current and arc length,as the penetration becomes more and more great,the weld pool surface collapses.The weld pool surface is no longer a hemisphere,the laser stripes reflect repeatedly on the concave of weld pool surface,so that the laser stripes on image screen is gathered.And the simulation result shows that the welding current has more significant effect on the penetration.(4)Through the GTAW welding test,we calculate the curvature radius rate of the laser stripe that reflected on the weld pool surface by using the designed algorithm.The dynamic change process of weld pool surface and the change of weld pool local flow pattern in welding were studied.The results show that the curvature radius rate of the laser stripes is large in the center of the weld pool,away from the center of the weld pool,the curvature radius rate is smaller and smaller.And the change rate of curvature radius of laser stripes shows that the spot is close to center position on the weld pool surface,the deformation of weld pool surface is larger.The change relationship between the rate of laser stripe's curvature radius changes and time also reflects the liquid metal's flow state in the plane XOZ to a certain extent.When the position is closer to the center of the weld pool,the liquid metal flow rate will be greater.