| Rivet connection is widely used in the rocket carrying cabin.Riveting is light in weight,simple in assembling process,stable in strength,easy to check and troubleshoot,and suitable for various metal and non-metallic materials of complex structures.Although manual riveting can basically meet product development requirements,but manual riveting labor intensity,rivet head forming consistency is relatively low,the stability of riveting quality is not easy to control,rivet processing hardening is serious,rivet head is easy to crack,nail bar is not easy to form interference quantity.The riveting force of electromagnetic riveting is mainly controlled by pressure parameters,the rivet head forming consistency is good,the deformation is completed when the electromagnetic rivet is fired once,there is no need for continuous hammering,the noise duration of riveting is shorter than that of pneumatic riveting.For the riveting of thick sandwich material,electromagnetic riveting can still form more uniform interference along the screw rod,which improves the load resistance and fatigue resistance of the structure.Aiming at the problem of interference between riveting die and product structure of arrow body,the article first carries on the statistical analysis to the riveting part,the product structure form,determines the suitable riveting mold diameter and the length.Then,the mechanical properties of riveting dies with different taper were selected for testing and the screw rod interference,shear strength and tensile strength of riveted joints were evaluated,and compared with the existing pressure riveting and pneumatic riveting process joint quality.The result of research shows that,the taper of riveting die increase,the amount of interference tends to decrease,the taper of riveting die is smaller,the larger the axial load is on the nail rod,the larger the deformation of the center material.With the increase of riveting taper,the shear strength decreases,and the smaller riveting taper is beneficial to riveting quality.With the increase of riveting taper,the tensile strength of electromagnetic riveting joint increases gradually,the lager taper of riveting die is beneficial to the tensile resistance of riveting.Compression riveting joint tensile strength is the highest,pneumatic riveting and electromagnetic riveting is basically the same.The microstructure of electromagnetic riveted parts was analyzed after cutting,it is concluded that the microstructure of tapered electromagnetic riveted joints is mainly divided into three regions: difficult deformation zone?deformation zone and widened adiabatic shear zone.Compared with the flat riveting die riveted joint,although the tapered riveting head still presents adiabatic shear zone,the shear zone area widens,the deformation of this area greatly slows down,and the trend of shear crack generation weakens.The dynamic deformation process of rivets under different riveting dies was simulated by ABAQUS,the result of research show that,when the inclination angle of riveting die changes from 40°~180°,the smaller the riveting die angle,the more easily the rivet material can be squeezed into the nail hole,a larger amount of interference is formed between the rivet and the hole wall,which is conducive to improving the fatigue life of the joint.The diameter of riveting chamber increase,and the radial flow of material increases,it reduces the extrusion on the sandwich material,the equivalent stress decreases along the thickness of the sandwich material.The results of numerical simulation are basically consistent with those of mechanical test. |
PDF Full Text Request