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

Springback Analysis and Drawing Process Research of B-pillar Inner Based on High-strongth Steel

Author ZhangZhao
Tutor LiJun; ZhangShuangJie
School Hebei University of Science and Technology
Course Materials Processing Engineering
Keywords High strength steel sheet Orthogonal test B-pillar inner Drawbead Springback Pam-stamp
Type Master's thesis
Year 2012
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Energy saving and environmental protection, and security has become the dominantdirection of the automotive industry. The use of high strength sheet metal in theautomobile cover meeting the two sides of requirements, so, the high strength sheet metalis more and more extensively used in the automobile mamifacturing.Because of lack of awareness to the mechanical properties of high strength sheetmaterials is, when the process parameters unreasonable, this will lead to poor formability,prone to crack, wrinkle, springback, and other deficiencies. In order to control deficiencies,improve the accuracy, using the numerical simulation technology to predict drawingdefects and optimize the drawing process of high strength sheet metal, in order to reducethe number of repairing and trying the die, shorten the car manufacturing circle.In this paper, take B-pillar inner as an example, through the finite element softwarePam-stamp to study the stamping formability and springback. Firstly, get mechanicalproperties of high strength low alloy steel B340LA through tensile test, and contrast withOrdinary low-carbon steel plate. Design the addendum and binder surface, and obtainedblank shape with Inverse module. Preliminary selecte process parameters include drawingspeed, die clearance, blankholder force and friction coefficient. Establishes finite elementmodel, after a preliminary simulation, get the thickness and FLD figure. Secondly, design the drawbead according to the forming limit diagram, and utilizeorthogonal test optimized drawbead size parameters R1, R2, L2and D, get the optimalresults: R1=6, R2=5, L2=20, D=7, avoid wrinkling. Then in order to control the crack, useorthogonal test to optimize the process parameters which include drawing speed, dieclearance, blankholder force, friction coefficient. Sort the influence of the four processparameters to the maximum thinning rate: f>F>V>G, and get the optimal combination ofprocess parameters: V=4mm/ms, F=700kN, G=1.32mm, f=0.10, avoid crack.After that analyzes trimming springback about B-pillar inner, get the law affectingspringback of the four process parameters, and control the springback within4.38mm viadie compensation. Finally, adjust the blankholder force and repair the die, avoid wrinklingand crack, and control the springback in3mm, qualified.

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