Evaluation of Formability and Drawability of Al 5182-O Using a Servo Drive Press DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Tingting Mao Graduate Program in Industrial and Systems Engineering The Ohio State University 2014 Dissertation Committee: Dr. Taylan Altan, Advisor Dr.Jerald Brevick Dr. Blaine Lilly Copyright by Tingting Mao 2014 Abstract The part drawability in stamping process can be improved by many factors, including blank geometry, lubricant, surface finish, the deformation speed and the blank holder force. Lowering the friction between the tool and the workpiece can reduce fracture potential in the part. Friction is affected by contact pressure, temperature, sliding velocity, die material/coating and surface texturing. In this study, only the effects of lubrication and surface were investigated. Various lubricants such as dry film lubricant and wet lubricants, which were developed for aluminum alloys, were evaluated using cup draw test. Tribological test such as cup draw test was utilized to evaluate the lubricity of the selected lubricants. It was found out that dry film lubricant performed better than wet lubricants in the deep drawing of aluminum alloys. Mill finish and Electrical Discharge Texturing (EDT) that are surface topographies for aluminum alloys, were evaluated by conducting cup draw test in the study. It was concluded that EDT can provide better lubrication condition at the interface between workpiece and die, compared to Mill Finish. Blank geometry can be optimized to improve the part drawability. In this study, different blank geometries were studied by using FE simulations to optimize the blank geometry to be used in the servo press tryouts. It was found out blank with an optimal blank shape, such as four corners chamfered blank shape, could give less wrinkling. ii Designing a proper tooling also can improve the part drawability by selecting the optimum punch/ die radii and punch and die clearance. In this study, FE simulations were conducted to determine the optimum punch and die radii and clearance between punch and die. By using a mechanical servo press, which can 1) vary the ram speed at any slide position and 2) vary the blank holder force through the stroke can improve the part by selecting the optimal deformation speed and blank holder force. In this study, the effect of ram speed and variable blank holder profile on part drawability was investigated. It was found out that a higher speed can form a better part. iii Dedication This document is dedicated to my husband (Yang Wang), my daughter (Alice Wang) and my son (Michael Wang) iv Acknowledgments I would like to express the deepest appreciation to my advisor, Dr.Taylan Altan for giving me the opportunity to pursue my graduate studies under his guidance. His encouragement and guidance are the main reasons for this research work to even be possible. I sincerely thank my co-advisor, Dr. Jerald Brevick, for all his inputs and kind support during last four years. I also thank my committee member Dr. Blaine Lily for his inputs and kind support. I would like to thank Dennis O’connor and Milan Jurich from Honda for providing all the support, especially for providing the aluminum blanks and tooling for conducting experiments required for my study. I would also like to thank Shrini Patil from AIDA and Cliff Hoschouer from Shiloh Inc. for providing AIDA’s press and Shiloh die tooling for conducting experiments. I thank my colleagues of the CPF, Adam Groseclose, Xi Yang, Ali Fallahiarezoodar, Siddharth Kishore, Ganapathy Srinivasan, Suraj Appachu, Chong Li and Xia Jin for the discussion and assistance during the course of my study. I especially want to think Long Ju for his discussion and help for my project. I thank my family and friends for all their support in this endeavor. At last, I would like to thank my husband Yang Wang and two of my kids (Alice Wang and Michael Wang) for their support during my PHD program. I would never have this achievement without their support. v Vita 2004................................................................B.S. Mechanical Engineering, Henan University of Technology 2010................................................................M.Sc. Mechanical Department, Southern Illinois University Edwardsville 2010 to present ..............................................PhD student, Integrated Systems Engineering, The Ohio State University Publications Mao, T., and Altan, T., “Aluminum sheet forming for automotive applications, Part 1”, Stamping Journal, January/February issue, p 12. Mao, T., and Altan, T., “Aluminum sheet forming for automotive application, Part II”, Stamping Journal, March/April issue, p 12. Mao, T., et al., “Applications of FE simulation for Stamping and Blanking of Sheet Materials”, Int. Conf. on “New Developments in Sheet Metal Forming”, May 13-14, 2014, IFU-Stuttgart. Fields of Study Major Field: Industrial and Systems Engineering vi Table of Contents Abstract ............................................................................................................................... ii Dedication .......................................................................................................................... iv Acknowledgments............................................................................................................... v Vita ..................................................................................................................................... vi Publications ........................................................................................................................ vi Fields of Study ................................................................................................................... vi Table of Contents .............................................................................................................. vii List of Tables ................................................................................................................... xiii List of Figures .................................................................................................................. xvi Chapter 1. Introduction ................................................................................................... 1 Chapter 2. Research Objectives and Approach .............................................................. 3 Chapter 3. Literature Review on Aluminum forming .................................................... 5 3.1 Material properties and formability........................................................................... 5 3.1.1 Wrought alloys designations ......................................................................... 5 3.1.2 Aluminum 5182-O material .......................................................................... 9 3.2 Determination of materials properties by the uniaxial tensile test .......................... 11 vii 3.2.1 Limitations of the tensile test ...................................................................... 11 3.3 Determination of material properties by the viscous pressure bulge (VPB) test .... 12 3.4 Conditions at tool/material interface ....................................................................... 14 3.4.1 Lubricants ................................................................................................... 14 3.4.2 Surface finish of aluminum sheets .............................................................. 19 3.5 Tests for evaluation of lubricants ............................................................................ 21 3.5.1 Cup drawing test (CDT).............................................................................. 21 3.5.2 Other tests available for evaluation performance of lubricants .................. 23 3.6 Design rules for tooling (deep drawing and stretch forming) ................................. 23 3.7 Simulation/deformation zone .................................................................................. 25 3.8 Servo press application on aluminum forming ....................................................... 27 Chapter 4. Determination of Material Properties of Al 5182-O using Uniaxial Tensile Test, Viscous Pressure Bulge Test (VPB tests) and Dome Test ....................................... 32 4.1 Determination of sheet material properties by the uniaxial tensile test .................. 32 4.2 Determination of sheet material properties by the VPB test ................................... 34 4.3 Comparison of flow stress data obtained from tensile test and bulge test .............. 36 Chapter 5. Experimental Evaluation of Selected Lubrication Conditions to Improve Stamping Quality .............................................................................................................. 38 5.1 Objectives ................................................................................................................ 38 viii 5.2 Approach ................................................................................................................. 38 5.3 Preparation of Experimental Evaluation for Various Lubrication Conditions Before starting cup drawing tests the following tasks are completed. ...................................... 39 5.3.1 Procurement of Sheet Materials and Lubricant Samples ............................ 39 5.3.1 Preliminary Evaluation of Lubrication Conditions ....................................