Dissertation
Dissertation > Industrial Technology > Metallurgy and Metal Craft > Metal pressure processing > Cold stamping ( sheet metal processing) > Cold stamping process

Study on Stamping-forging Process and Experiment of Sheet Metal Parts with Non-uniform Thickness

Author LuoJianCheng
Tutor WangXinYun
School Huazhong University of Science and Technology
Course Materials Processing Engineering
Keywords flanging and extruding stamping-forging process powerful backward thickening-drawing process FEM
CLC TG386
Type Master's thesis
Year 2011
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With the rapid development of manufacturing industry, the requirements for parts’ mechanical properties and assembling accuracy become higher and higher, and energy-saving, environmental protection is the commonly focused topic all over the world, which constantly actuate the reform and innovation of new processes and technologies. Stamping-forging process of sheet metal with non-uniform wall thickness stands at front of the advanced manufacturing industry, which is a newly developed net shape technology. It organically integrates the stamping process and forging process and can be applied to overall plastic formation of structural parts with large surface area and large-thickness-difference, such as clutch wheel, hub of wheel and structure parts of many electronic products.In this paper, sheet metal flanging and upsetting process were simulated using the general FEM method. The rolling anisotropy, elastic modulus, initial yield stress, hardening exponent and initial thickness of sheet were studied on their effects on final spring back angle of the steel sheet. A new extruding method was proposed as "varying section and floating bar extruding method". The principle of the new method was explained in detail as well as the best matching relationship between punch and floating bar. The stress and strain distribution was compared between the new method and traditional extruding process on the same part, and the result showed that the stress and strain distribution is more homogeneous under the new method.The process analysis and mould design were implemented according to the requirements of a double-cylinder-shaped part, which were experimentally verified using double-action plate hydraulic punch press Y28-500. The influence of gap between convex-concave punch and fixed die on powerful backward thickening-drawing process was studied. The velocity matching relationship between outer cylinder and insider cylinder was derived and proven by experiments. Thicknesses at sixty uniformly distributed points along the cross section of the double-cylinder-shaped part were measured and the thickness curve was generated illustrating the law of thickness distribution along the section. At last, an optimized process of an aluminum alloy pan with non-uniform wall thickness was proposed, which successfully reduced the forming force.

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