Research On Stretch Forming Of Multi-point Die Based On Swinging Unit

Sheet metal forming is an important part of modern manufacturing. It is widely used in manyaspects of social production with the processing of high precision, low cost, easy to automatedproduction and other advantages. However, with the rapid advances in social and economicdevelopment, people are no longer satisfied with getting uniform and large-scale industrialproducts, and a gradual transition to the pursuit of diversified and personalized products isbecoming more and more popular. The traditional stamping can not meet this new demand, somulti-point forming comes into being. Multi-point forming has feature of discrete and adjustabledie, making it fit to form a variety of different sheet shapes. But the discrete die brings lowerquality, easy to produce indentation, wrinkling, fracture and other defects. Therefore, a new designof discrete die is badly in need to solve these above problems.Multi-point die with swinging unit is a new type of flexible sheet metal forming methodcombined the existing multi-point die and the flexible clamp stretch forming. The basic principleof flexible clamp stretch forming is using flexible discrete clamps instead of the solid clamp, withgood flexibility, good fitness to the mold, high material utilization, good forming quality, etc.Swinging unit is based on the traditional fixed unit and takes new unit model, which fits for thesheet metal according to different profiles. In the process of adjustment of each unit, die profile isfinally consistent with target profile. Because the final die profile is relatively close to the targetand the greater area the sheet metal contacts with the die surface, it can effectively inhibit theindentation in the process sheet metal forming and get high quality forming parts with a uniformdistribution of stress and strain and little springback due to the high proximity between the finaldie profile and the target. Therefore it has an excellent prospect and research value.The conclusions:1. Research on principle of flexible clamp and swinging unit stretch forming Carry on research on principle of flexible clamp and swinging unit stretch forming andanalyze their characteristics and advantages of this combination.2. Establish fixed unit and swinging unit multi-point die finite element modelsEstablish multi-point die finite element models with fixed unit and swinging unit based onthe principle of flexible clamp and discrete die. Carry on research on the materials model, unitselection, meshing, and boundary conditions, the definition of contact and friction involved in thenumerical simulation. Discuss the setup procedure of multi-point die finite element models withswinging unit and flexible clamp. Lay the foundation for the numerical simulation of sheet metalforming process.3. Research on the results of strech forming with fixed unit and swinging unit.Form the spherical part and the saddle part for fixed unit and swinging unit in the method ofnumerical simulation. Compare the results of the results, discuss the swinging unit advantage informability, surface quality, stress and strain distribution and thinning rate over fixed unit. It canbe drawn that the stretch forming with swinging unit is better than fixed one.4. Comparatively research on the impact of elastic cushion thickness to stretch formingwith fixed unit and swinging unit.Taking the spherical part and the saddle part for example, perform numerical simulations indifferent elastic cushion thickness and discuss the impact of elastic cushion thickness to stretchforming with fixed unit and swinging unit. The results show that the elastic cushion cansignificantly improve shaping effect for both fixed unit and swinging unit. However, the swingingunit has excellent formability, and is comparable to the fixed unit with elastic cushion. Thus thedegree of improvement on fixed unit is significantly higher than the swinging unit. It can be drawnthat swinging unit has excellent formability, can replace fixed unit with elastic cushion partly andsimplifies the operations process.5. Comparatively research on the stretch forming results of solid elastic cushion anddiscrete elastic cushion.Make the solid cushion discrete to fixed unit and swinging unit and form the spherical part.Through the comparision of simulation results, light map, stress and strain, thickness, surfacequality, forming precision, springback, the improvement of discrete elastic cushion is similar to the results of and solid elastic cushion under certain thickness. As the thickness continues toincrease, the advantages of the solid elastic cushion are more obvious. In conclusion，the discreteelastic cushion can replace the same thickness of the solid elastic cushion and simplify theoperation processing.