Study On The Test Method Of Deep Drawing Without Holder For Cylindrical Parts Of Orthotropic Plasticity In Sheet Metals

Earing test is an important way to verify the reliability of anisotropic plasticity theory,an important means of plate anisotropy research,and an indispensable link in the development and application of anisotropic yield criterion.However,there are still some problems worth discussing in traditional earing tests(such as GB/T15825.7-2008 "Forming Properties and Test Methods of Metal Sheets-Part 7: Lug Test"): During the test,the friction force brought by the blank holder is very large and cannot be ignored,so the force on the plate element is complex,and the academic community has not yet developed a method to quantitatively calculate the change of friction during the forming process.During the forming process,the sheet metal and the mold will be displaced relative to each other,but it cannot be determined whether the huge friction force generated by this process will affect the macroscopic performance of the sheet metal anisotropy.In this thesis,based on the Hill48 anisotropic yield criterion,the in-plane anisotropy of the rolled sheet is analyzed,and a complex drawing and reverse drawing test method without blank holder is proposed.In this thesis,the calculation method of the number and orientation of the lugs when the sheet is drawn is obtained by analyzing the in-plane anisotropy of the rolled sheet,and then the uniaxial tensile tests are carried out on DC01,DC04 and DC06,the mechanical properties and anisotropy parameters of the materials are determined,and the number and orientation of the lugs of the three materials are calculated.The DC04 rolled sheet with 1mm thick is simulated by Dynaform,and the factors affecting the drawing effect in the complex drawing and reverse drawing are analyzed.The simulation finds that it mainly depends on the two times drawing for the drawing effect of the complex drawing without blank holder,so it is particularly important for the reasonable distribution of the drawing coefficient.In addition,the influence of the fillet radius of the conical die,the fillet shape of the punch and die,and the drawing stroke on the drawing result is studied in this thesis,and the mold parameters that can realize the complex drawing and reverse drawing process without blank holder are finally determined.The simulation results verify the feasibility of this experiment.With the help of Abaqus,the stresses and strains of the sheet at different radius positions and different angle elements are analyzed by Abaqus,and the performance of the sheet anisotropy in terms of stress and strain is analyzed,which verifies the applicability of the complex drawing and reverse drawing test method without blank holder to the Hill48 anisotropic yield criterion.The physical tests are carried out for complex drawing and reverse drawing test method without blank holder,and the test results of the three materials,DC01,DC04 and DC06,are compared.The test results show that it is accurate for the Hill48 anisotropic yield criterion to predict the number of the earings of orthotropic rolled steel sheet,but the calculated (?) is a bit large.