Equipment Design Of High Speed Refill Friction Stir Spot Welding

A very important spot welding method in modern industrial system is refill friction stir spot welding.This topic explores the high-speed refill friction stir spot welding,puts forward four kinds of design,and designs a refill friction stir spot welding equipment on this basis,and independently designs the key parts of the equipment,and successfully creates an intelligent human-computer interface,uses the solder joint temperature to build BP classification neural network for prediction,with low average relative error,It can meet the application standard.PID closed-loop control delay compensation model is added to make up for the defects of the system.The welding experiment of aluminum alloy with the thickness of 2mm was carried out by using the custom welding stir head.It is proved that the selection of welding parameters has a direct effect on the mechanical properties of the formed joint.This paper mainly introduces the design and implementation process of refill friction stir spot welding equipment from the aspects of equipment selection,mixing head design,etc.,designs the mechanical device,and uses the external drive mode to realize the pumping operation of refill friction stir spot welding equipment.This is also an important foundation for its refill action.The core device is mainly composed of rotating chuck,lead screw,guide rail,slider,holding sleeve,moving plate,shoulder type oil-free bushing,straight cylinder type oil-free bushing and coupling.Through the design of electrical wiring and control,the automatic control system of relative movement between stirring needle and sleeve is constructed to realize welding.Based on the understanding of the refill friction stir spot welding,according to its movement mode,the design of double spindle is adopted,combined with the reasonable structure of the mixing head,the rotation and down binding movement of the sleeve and the mixing needle are controlled separately.In the aspect of welding process control,PLC + CNC control mode is adopted.By adding subroutines in the program,the accurate control of down binding and refilling of mixing needle and sleeve is realized.Using PLC + CNC mode,the precise control of the joint movement of the sleeve and the stirring needle is realized.This paper also analyzes the characteristic parameters of the refill friction stir spot welding equipment and the correlation between the parameters and the welding process.After the temperature model is established by genetic BP neural network algorithm,the model is extracted as the control object,and a closed-loop temperature control model is constructed.Through the simulation software,the parameters of the above equipment are optimized.The refill friction stir spot welding equipment designed in this paper is used for the corresponding process test.Under the condition of welding speed 4800 r / min and other parameters,the solder joint has beautiful macro forming and even keyhole refill.The test results show that there is no significant defect on the surface of the solder joint.Moreover,the microstructure in the stirring zone is fine and dense.Under the influence of welding thermal cycle and mechanical stirring,the grain size of mechanical zone is not consistent.And the grain diameter of heat affected zone is larger.The hardness distribution of all welded joints presents obvious "W" shape.Significant softening was observed at the joint.The peak value of hardness in the mixing zone is 81.2%(78hv)of the wood,while the lowest value at the junction of the heat affected zone and the thermo mechanical zone is only 61.5%(59hv) of the base metal.