LIST OF CONTENTS

Deep Drawing

At UMIST, when I started my masters, I had no idea that I would find my self involved in research on one of the very fundamental and important manufacturing process … The Deep Drawing … I enjoyed working in this area under the guidance of my kind and helpful supervisor Dr. John Atkinson. I have placed my thesis as it is on the following pages. You are allowed to reproduce or copy it as long as you give adequate reference to my work. This study was kindly funded by NUST and the government of Pakistan.

Choudhry, R. S., “Profiling of blank holder pressure in deep drawing”, MSC Thesis, The University of Manchester Institute of Science and Technology, Sep. 2004.

Disclaimer: All care has been taken to produce this thesis as accurately as possible. However the author claims no responsibility if the information contained herein results in any loss or damage.

LIST OF CONTENTS

Title Page
Abstract …………………………………………………………………………………...						i
Dedication…………………………………………………………………………………						ii
Declaration………………………………………………………………………...............						iii
Acknowledgements………………………………………………………...............................						iv
List of Contents……………………………………………………………………………						v

Chapter 1		Introduction………………………………………………………………				1
1.1	Introduction ……………………………………………………………………….					2
1.2	Background………………………………………………………………………...					2
1.3	Aim and objectives………………………………………………………………...					4
1.4	Structure…………………………………………………………………………...					5
1.5	Conclusion…………………………………………………………………………					7

Chapter 2		Deep Drawing Process Fundamentals……………................................				8
2.1	Introduction………………………………………………………………………..					9
2.2	The process description……………………………………………………………					9
2.3	Exploring defects …………………………………………………………………					12
	2.3.1		Tearing……………………………………………………………………			12
	2.3.2		Wrinkling…………………………………………………………………			14
	2.3.3		Elastic springback………………………………………………………...			15
	2.3.4		Earing……………………………………………………………………..			16
	2.3.5		Ironing…………………………………………………………………….			17
2.4	Analytical calculations…………………………………………………………….					17
	2.4.1		Limiting drawing ratio……………………………………………………			17
	2.4.2		Calculation of basic parameters…………………………………………..			19
			2.4.2.1		Cup height………………………………………………………	19
			2.4.2.2		Maximum punch force………………………………………….	20
2.5	Formability………………………………………………………………………...					22
	2.5.1			Tensile test………………………………………………………………..		23
	2.5.2			Cupping tests……………………………………………………………...		23
	2.5.3			Bulge test…………………………………………………………………		23
	2.5.4			Forming limit diagram (FLD)…………………………………………….		24
2.6	Blank holder force…………………………………………………………………					25
	2.6.1			Inclusion of wrinkling limits……………………………………………...		26
2.7	Conclusion…………………………………………………………………………					26

Chapter 3			Advancements In Blank Holding Force Control………………………			28
3.1	Introduction………………………………………………………………………..					29
3.2	Developments in FLD and WLC………………………………………………….					29
3.3	Blank holder force (BHF) control strategies………………………………………					34
	3.3.1		Decreasing BHF profiles………………………………………………….			35
	3.3.2		Increasing BHF profiles…………………………………………………..			36
	3.3.3		Pulsating BHF profiles……………………………………………………			37
	3.3.4		Modelling of BHF trajectories……………………………………………			38
	3.3.5		Feed back control systems for BHF profiling…………………………….			39
	3.3.6		Controlling springback through BHF profiling…………………………..			40
	3.3.7		Flexible and segmented blank holders- Spatial and temporal profiling of BHF……………………………………………………………………….			42
3.4	Conclusion…………………………………………………………………………					46

Chapter 4			Experimental Set-up And Methodology……………………………….			48
4.1	Introduction………………………………………………………………………..					49
4.2	The Drawing Press………………………………………………………………...					49
4.3	Changes in the existing set up……………………………………………………..					51
	4.3.1		Criteria for selection of strategy to control BHF…………………………			51
	4.3.2		Implementation of strategy to control BHF………………………………			52
	4.3.3		Recording data……………………………………………………………			58
			4.3.3.1		Key parameters…………………………………………………	58
			4.3.3.2		Set up for data acquisition……………………………………...	59
4.4	Verifying the set-up………………………………………………………………..					63
4.5	Methodology………………………………………………………………………					69
4.6	Conclusions………………………………………………………………………..					70

Chapter 5			Results and discussion of results……………………………………….			71
5.1	Introduction………………………………………………………………………..					72
5.2	Preliminary test……………………………………………………………………					72
5.3	Determining the tearing limit diagram ……………………………………………					74
5.4	Ramping tests……………………………………………………………………...					77
5.5	Critical draw depth range………………………………………………………….					81
5.6	Stepped and ramped BHF profiles………………………………………………...					84
5.7	Issues of repeatability……………………………………………………………...					87
5.7	Conclusion…………………………………………………………………………					89

Chapter 6			Conclusions………………………………………………………………			91
6.1	Introduction………………………………………………………………………..					92
6.2	Guidelines for effective use of BHF profiling…………………………………….					92
6.3	Limitations and Future Research Directions………………………………………					93

References…………………………………………………………………………………						95
Appendix 1………………………………………………………………………………...						104