Research On Magnetic Pulse Crimp Bonding Technology And Performance Of Aluminum And Magnesium Drive Shaft Joint

Nowadays,resource and environmental problems are becoming more and more serious,and the demand for lightweight automobiles is very urgent.The use of lightweight materials is an effective way to reduce the weight of automobiles.Aluminum alloy materials have high specific strength and good corrosion resistance,and have been widely used in the automotive ind ustry.Magnesium alloy is a popular lightweight material in recent years,with the characteristics of low density and light weight.Dissimilar materials will inevitably involve the problem of reliable connection.As a new type of environmentally friendly a nd efficient connection technology,magnetic pulse crimping technology has been applied in many industries.In this paper,structural glue is added on the basis of this process,and magnetic pulse crimp bonding technology is proposed to realize the effective connection between aluminum and magnesium alloy tube fittings.Research is carried out through several aspects such as numerical simulation,mechanical performance testing,microscopic and hardness observation,and salt spray corrosion performance testing.First,a drive shaft tube and shaft fork connection structure for the lightweight drive shaft of an automobile is proposed.Use 6061 aluminum alloy shaft tube and AZ31B magnesium alloy shaft fork to replace the original steel parts,complete the selection of shaft tube and related size design through torque calculation,and use magnetic pulse crimping technology to connect the them.Then,the magnetic pulse crimping process is numerically simulated.Based on the LS-DYNA software coupling electromagnetic field and structure field,the distribution and change of physical quantities such as current density,magnetic induction intensity,Lorentz force,outer tube deformation speed and deformation amount are analyzed.With the increase of discharge energy,the three electromagnetic parameters of maximum current density,magnetic induction and maximum Lorentz force also increase,and the time it takes for the outer tube to reach the maximum deformation is correspondingly reduced,which provides guidance for subs equent process tests.Using an Photonic Doppler velocimeter to measure the deformation speed of the outer tube,it is found that the difference between the experiment and the simulation is 3.48%,which proved the reliability of the numerical simulation.Then,design and complete the magnetic pulse crimping process test according to the conclusion of the simulation.The three process parameters of discharge energy,discharge times and magnesium alloy groove angle are respectively changed to explore the static torsion strength and failure mode of the joint.There are two joint torsion failure modes:the outer tube is twisted out and the outer tube is twisted,both of which appear at the joint.The maximum torque obtained after changing the different process parameters is 961.99N·m.After that,structural glue is added on the basis of the magnetic pulse crimping process,and a magnetic pulse crimp bonding process is proposed.Determine the gluing parameters and process sequence and complete the connection experiment.The static torsional failure modes of magnetic pulse crimp bonding joints are divided into two types:the mixed failure of the glue layer at the joint and the failure of the base material.Under appropriate parameters,the maximum torque of the joint reaches 1479.25N·m and the failure of the base material occurs,which can meet the static torsion requirements of the drive shaft.Microscopic analysis of the distribution law of the adhesive layer,the thinning of the outer tube and the hardness change of the two alloys,it is found that the aluminum alloy outer tube will be thinned at the top fillet R ₁ of the groove,and the Vickers hardness will also increase.Finally,neutral salt spray corrosion is performed on the two types of joints.As the corrosion cycle increases,the corrosion degree and products of the two types of joints increase,but the weight decreases.The addition of adhesive greatly reduces the formation of galvanic cells between the two metals.Therefore,the corrosion resistance and static torsion strength reduction of the magnetic pulse crimp bonding joints at the same time are better than that of the magnetic pulse crimping joints,and the mechanical properties of the them are reduced.Analyzing the failure modes of the two types of joints after corrosion,the magnetic pulse crimp bonding joints are all glue-layer mixed failures,and when the corrosion period of the magnetic pulse crimping joints is short,the joints are still twisted,but when the corrosion period is long enough,The aluminum tube at the end face cracked first in the torsion test due to excessive corrosion.