Modeling and Control of the Springback Effect in the Bottom Sheet Metal Part One-Stage Drawing Process

• Main Authors: A. S. Chumadin, D. A. Baturin
• Format: Article
• Language: Russian
• Published: MGTU im. N.È. Baumana 2014-01-01
• Series: Nauka i Obrazovanie
• Subjects: springback; sheet-forming process; bottom part; method of springback manage; reducing labor; finite element analysis
• Online Access: http://technomag.edu.ru/jour/article/view/681

<p>The main objective of this study is to reduce a manufacturing complexity of bottom sheet metal parts by improving the accuracy of parts produced. This study is aimed at using the finite element analysis to prove assumptions that there is a transition frontier between the processes of forming and drawing, and there are capabilities to control springback effect by moving this frontier positions.</p><p>The process, the stress-strain state of which in the dome corresponds to the process of forming parts, and in the flange area to the drawing process, was considered to be a formingdrawing process.</p><p>Based on previous studies, techniques to reduce a springback have been proposed which enable us to use three calculation schemes for the process simulation:</p><p>The frontier transition position control between the processes of forming and drawing by changing the contact pressure on the flange by varying the frictions coefficients on the die and binder surfaces;</p><p>Springback manage through the additional tensile forces in the flange area of the blank;</p><p>Springback manage through the technological insert at the first process stage.</p><p>For ease of comparison with previous research results the same geometric parameters and material properties of the items are used in the simulation.</p><p>The springback analysis used a finite element method in the AutoFormTM incremental module with automatically mashed and standard tolerance computation properties. The blank, binder, punch, and die were then imported to the module by CATIATM interface in .iges format.</p><p>The calculation has shown that the optimal value for the least thinning and springback parts are available for the second scheme whereby ring punch makes additional tension in the flange area (from 1.09 to 0.35 mm with thinning from 0.80 to 0.73 mm). The use of flange retention of sheet blank at the expense of variable frictional forces showed the springback value reduction by 4 times (from 1.09 to 0.27 mm). However thinning was 16% (from 0.80 to 0.63 mm).</p><p>Application of the scheme with technological insert allowed us to achieve the least thinning of the blank material (from 0.80 to 0.75 mm), but with only 1.8-fold (from 1.09 to 0.69 mm) springback decrease.</p><p>As a result, it is found that in bottoms manufacturing the most preferred in terms of the smallest springback is the predominate forming zone, and the position of the transition frontier between the forming and drawing processes should be behind the cutting line of flange.</p>