Research On Climbing Wall Robot Structure And Electrostatic Adsorption In Ultrasonic Detection For Railway Vehicle Welds

Resistance spot welding is an important welding method in the manufacture of rail passenger cars.Especially in the stainless steel structure car body,the spot welding process accounts for more than 70%of the entire manufacturing process.Spot welding has an irreplaceable role in vehicle manufacturing.But for resistance spot welding,the quality of solder joints is affected by various factors such as the surface state of the material,the shape of the electrode,the loading voltage,the welding time,and the electrode pressure.The welding core is also in a sealed state,which makes it difficult to evaluate the quality of the welding spot.While it is of great significance to ensure the quality of the solder joints to ensure the safety of the railcar body.At present,most of the quality evaluation of resistance spot welding is only in the laboratory stage.Therefore,in order to guarantee the quality of solder joints,non-destructive testing of solder joints is particularly important.During the overhaul of rail passenger cars,the solder joints has always been a part of negelecte,This is because there is still no complete system on the market that can solve the post-weld inspection of rail vehicles.There are mainly three difficulties in the nondestructive testing of welded joints of rail passenger cars.First,how to realize the traceability of solder joints in the mass production of rail vehicles and the large number of solder joints;Second,after the car body is formed,it is necessary to build a scaffold during manual inspection,and there are many welding spots and the position of the welding spot is difficult to determine;The three is how to evaluate the quality of solder joints correctly by using ultrasonic data.In order to solve the practical problems in the automatic detection of vehicle body solder joint,this paper introduces intelligent wall moving mechanism to realize automatic intelligent ultrasonic inspection of solder joint based on the laboratory's research of on-line monitoring of solder joint and post-weld ultrasonic testing in laboratory.Wall moving mechanism as a kind of mechanism that can move automatically on the surface of vertical wall and even he lower surface of the ceiling,the stable and reliable adsorption force is a problem that should be emphasized and prioritized when designing a wall moving mechanism.To ensure the safety of the surface mobile mechanism,this paper simplifies the structure of the multi-crawler wall moving mechanism,analyze the spatial attitude of the mechanism,and transforms the static analysis in the three-dimensional space into a steady state study of a specific plane,and obtain the stability conditions of the mechanism to guide the overall structural design.In terms of adsorption method,considerate the mechanism characteristics of the vehicle body,Electrostatic adsorption is used to achieve stable adsorption of the entire mechanism.Analyze and study the mechanism of electrostatic adsorption,and build adsorption force model of bipolar electrostatic adsorption electrode on conductor and dielectric surface based on Coulomb interaction and J-R effect.And analyze the main factors affecting the electrostatic adsorption force,such as the electrode thickness,loading voltage and electrode topology,which lays a theoretical foundation for electrode optimization.The two-dimensional and three-dimensional structures of the electrodes were analyzed by Ansoft Maxwell and Comsol multiphysics to verify the accuracy of the adsorption force model,and further analyze the influence of the electrode topology on the electrostatic adsorption force,provide theoretical guidance for the topology design of the electrostatic adsorption electrode.Using distributed system design ideas to design the hardware and software structure of the machine system,Through Bluetooth,the interaction between the upper computer and the lower computer can be realized to realize the motion control of the mechanism such as wall transition and steering.Based on A*algorithm,this paper studies the overall autonomous path planning and motion performance of the mechanism,and on the basis of the above research,the prototype of the wall moving mechanism of the rail bus is developed.It is proved that the prototype has the advantages of high automation,high positioning accuracy and reliable motion,etc.,which can realize the automatic quality detection of the solder joints of the vehicle body.