Research On The Performance Of Deflection Angle Electromagnetic Riveting Joint And Its Automation Realization And Control

Electromagnetic riveting is a new type of magnetic pulse connecting process,which is characterized by the deformation of rivet by using stress wave generated at high speed molding.Electromagnetic riveting has wide application prospects in the automotive field for various materials adaptability and high fatigue life characteristics of the connection.In this paper,aiming at the potential application requirements of automated electromagnetic riveting using mechanical arm,the numerical simulation and technological performance test of electromagnetic riveting by 2A10 aluminum rivets are carried out for the problem of angular riveting.And the shear and pull-off performance,Microstructure of pier head,macroscopic morphology of pier head and macroscopic morphology of riveted joint are studied.At the same time,aiming at the deflection of the mechanical arm under the impact force,a simple method is used to calculate the deflection angle and the method of angle correction is studied.The main research contents are as follows:Firstly,using ABAQUS to simulate the bias angle electromagnetic riveting process.The results show that the main deformation process of the rivet is divided into two stages: the overall upset of the nail rod and the local upset of the pier head.The exposed nail rod material has radial flow to form the pier head,and the pier head riveted by the partial angle can form a wedge-shaped pier head consistent with deflection riveting die.The temperature distribution and strain distribution in the nail rod are consistent,and as the deflection angle increases,the maximum strain and the maximum temperature increase.The residual stress distribution of the riveted joint and the gap at the joint between the two plates show that the fatigue life of the joint decreases as the deflection angle increases.Secondly,the mechanical properties and microstructure of riveted joints of various angles are studied.The results show that the shear strength and stiffness of the biased riveted joint gradually decrease with the increasing deflection angle.The metallographic morphology shows that the rivet pier head of each angle is deformed violently,and the obvious adiabatic shear band appears in the pier head.The shear band of the 0 ° rivet pier head is symmetrical with respect to the center line,and the shear band on one diagonal is more obvious.The difference of the contact length between the right and left sides of the angle pier and the plate explains the drop of the pull-off strength,and the gap between the nail rod and the nail hole in the joint shows the decrease of the fatigue strength.Finally,aiming at the mechanical arm automatic electromagnetic riveting system,the angle of the end face of the mechanical arm’s forearm subjected to the electromagnetic riveting impact force is calculated by using the energy method and the correction coefficient,and then kinematics modeling,kinematics positive and inverse solution of the mechanical arm can be carried out by using the D-H method.According to the effect of partial angle on the performance of the joint,for riveting working conditions requiring angle correction,the position and pose information matrix of the end effector corresponding to the rivet can be multiplied by an angle transformation matrix,so that the corrected end effector pose information matrix can be obtained,and the corrected control parameters can be obtained by inverse kinematics.