Design Rules Analysis For Sheet Metalworking Using Cad Tools.
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
DESIGN RULES ANALYSIS FOR SHEET METALWORKING
USING CAD TOOLS
This report submitted in accordance with requirement of the Universiti Teknikal
Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering
(Manufacturing Design) with Honours.
by
SHALIZAH AMAN SHAH
FACULTY OF MANUFACTURING ENGINEERING
April 2009
DECLARATION
I hereby, declared this report entitled “Design Rules Analysis for Sheet
Metalworking Using CAD Tools” is the results of my own research except as cited in
references.
Signature
:
…………………………………………..
Author‟s Name
:
…………………………………………..
Date
:
…………………………………………..
APPROVAL
This report is submitted to the Faculty of Manufacturing Engineering of UTeM as a
partial fulfillment of the requirements for the degree of Bachelor of Manufacturing
Engineering (Manufacturing Design) with Honours. The member of the supervisory
committee is as follow:
(Signature of Supervisor)
……………………………
(Official Stamp of Supervisor)
ABSTRACT
Sheet metal design is a critical part in the process of product design and
development. The entire quality of design influences the product performance,
product quality and cost of product. An optimal design can only be created based on
experiences and knowledge. The problem of frequent redesign occurs due to have no
well-documented rules in designing of sheet metalworking. The study of this project
is to investigate the design parameters of sheet metalworking and analyze the design
rules of sheet metal that influences the bending operation. Computer-Aided Design
(CAD) and Finite Element Analysis (FEA) are applied in this study in order to
design of safety factor and simulate the structural of bending parts. Bend allowance
has strong relationship to determine the safe area in designing of sheet metalworking.
As a result, a comprehensive set of design rules for sheet metal parts has been
generated and assisted in reducing an infeasible design, cost and production cycle
time.
Keyword: Bend Allowance, CAD, Design Rules, FEA, Sheet Metal.
i
ABSTRAK
Rekabentuk kepingan logam merupakan komponen yang kritikal dalam proses
rekabentuk dan pembangunan produk. Hal ini kerana kualiti sesuatu rekabentuk
secara keseluruhannya akan mempengaruhi kebolehgunaan produk, kualiti produk
dan kos produk. Oleh yang demikian, peraturan rekabentuk memainkan peranan
penting pada peringkat ini. Masalah yang terjadi dalam industri ialah tiada peraturan
yang didokumenkan secara formal. Rekabentuk yang optimum hanya boleh
dihasilkan berdasarkan pada pengalaman dan pengetahuan semata-mata. Projek ini
mengkaji tentang parameter-parameter rekabentuk kepingan logam dan menganalisis
peraturan rekabentuk kepingan logam yang mempengaruhi proses bending. Perisian
Computer-aided Design (CAD) dan Finite Element Analysis (FEA) diaplikasikan
dalam projek ini untuk merekabentuk faktor keselamatan dan mengsimulasi
struktural bahagian bending. Manakala bend allowance pula berkait rapat bagi
menentukan bahagian yang selamat dalam merekebentuk kompenan atau produk
kepingan logam. Pada penghujung projek ini, satu set peraturan rekabentuk kepingan
logam yang komprehensif dibentuk dan ianya dapat membantu mengurangkan
rekebentuk, kos dan kitaran masa pengeluaran yang tidak relevan.
Kata kunci: Kepingan Logam, Peraturan Rekabentuk, Proses bending, FEA, CAD
tools.
ii
DEDICATION
For my dearest mom and dad.
iii
ACKNOWLEDGEMENT
This research was performed under the supervision of Mr. Taufik, whom I like to
thank for the freedom granted in carrying out this project. I also would like to
express my deepest appreciation for Mr. Taufik in understanding regarding
difficulties I had during the project. Not forgetting to gratefully acknowledge to Mr.
Sapto Wahyono Widodo in spending his time for consultation according to Finite
Element Analysis (FEA). I would like to express my appreciation to Mr. Abdul
Halim Hakim Bin Abdul Aziz and Mr. Amri Bin Sulaiman for being my panels and
that they spend time to evaluate my report. A special thanks to all my friends and
others who had work together in assisting my project, I could not achieve it without
their support and encouragement. Last, but certainly not least the continual support
and patience of my parents is deeply and sincerely appreciated.
iv
TABLE OF CONTENTS
ABSTRACT……………………………………………………………………...……i
ABSTRAK……………………………………………………………………...…….ii
DEDICATION…………………………………………………………………...…..iii
ACKNOWLEDGEMENT………………………………………………………..….iv
TABLE OF CONTENTS……………………………………………………...……...v
LIST OF TABLES…………………………………………………………...……….x
LIST OF FIGURES…………………………………………………………..……..xii
LIST OF ABBREVIATIONS AND SPECIALIZED NOMENCLATURE……......xvi
LIST OF APPENDICES…………………………………………………….……..xvii
CHAPTER 1 INTRODUCTION…………………..….……………………………1
1.1
Background of Study………………………………..………………..…...….1
1.2
Problem Statement…………………………………………..………………..3
1.3
Objective of PSM……………………………………………………...…..….3
1.4
Scope of Work…………………………………………………….....……….4
1.5
Schematic of Project……………………………………………………....….4
1.6
Gantt Chart…………………...…………………………………...…………..5
CHAPTER 2 LITERATURE REVIEW……...…………………………….…...…8
2.1
Introduction…………………………………...………………...…………….8
v
2.2
Sheet Metalworking……………………………………..………………..…..8
2.2.1
Sheet Metal Forming Process……………………………………………..….9
2.2.2
Determining material properties of sheet metal on a press brake………...…10
2.2.3
Type of Sheet Metalworking…………………………………………......…11
2.2.3.1 Aluminum Alloys………………………………………......……………..…11
2.2.3.2 Copper……………………………………………...………………………..13
2.2.3.3 Steel………………………………………………...………………………..13
2.2.3.4 Titanium ……...……………………………………………………..…....…14
2.3
Material Properties…………………………………………………………..16
2.3.1
Tensile Strength……………………………………………………………..16
2.3.2
Fatigue…………………………………………..…………...………..……..16
2.4
Design for Sheet Metalworking………………………………...…………...17
2.5
Bending…………………………………………….....…………….……….18
2.5.1
Sheet Metal Bending…………………………………………..…...….…….19
2.5.2
Bending Terminology……………………………………………..……...…19
2.5.3
Bend Allowances………………………………………………..…………..21
2.5.4
Bending Force……………………………………………………………….25
2.5.5
Bending Models……………………………………………………...……...26
2.5.6
Computer aided process planning for sheet metal bending:
A state of the art…………………………………………………………….27
2.6
Press Brake……………………………………………………...…………...28
2.6.1
Press Brake Operations……………………………………………..…...…..30
2.6.2
Structural Analysis and Optimisation of Press Brakes…………………...…30
vi
2.7
Design Rules……………………..………………………………………….31
2.7.1
Inter-features Rules…………………………………………...…………..…32
2.8
Mathematical Modeling…………………………………………..……..…..34
2.9
Computer-aided Design (CAD)………………………………………..……36
2.10
Design for Manufacture (DFM)………………………………………..……37
2.11
Finite Element Analysis (FEA)………………………………………......….39
2.11.1 Introduction to Finite Element Analysis (FEA)…………………...……...…39
2.11.2 General Techniques and Terminology of FEA……………………...…...….41
2.11.3 A General Procedure for Finite Element Analysis………………..…...……43
2.11.3.1Preprocessing………………………..……………………………..……….43
2.11.3.2Solution………………………..……………………………………………44
2.11.3.3Postprocessing……………………...………………………………….……44
2.11.4 Example of Finite Element Analysis (FEA)…………………………….…..45
2.11.5 Finite Element (FE) Modeling………………………………..………….….46
2.11.6 Deformation Path………………………………………..……………….….47
CHAPTER 3 METHODOLOGY AND MATERIALS…………………….…....48
3.1
Introduction…………………………...………………………………..……48
3.2
Methodology…………………………..……………………….……………48
3.3
Description of the Methodology………………………..……………..…….50
3.4
Method to Conduct a CATIA simulation……………………………………55
3.4.1
Creation of the Part in Generative Sheet Metal Design……………………..55
3.4.2
Entering the Analysis Solutions……………………………………………..55
vii
3.4.2.1 Step 1: Mesh Generation…………………………………………………….55
3.4.2.2 Step 2: Assigning Material Properties……………………………………....55
3.4.2.3 Step 3: Applying Restraint and Load………………………………………..56
3.4.2.4 Step 4: Launching the Solver………………………………………………..57
3.4.2.5 Step 5: Postprocessing…………………………………………………...….57
CHAPTER 4 RESULTS…………………………………………………………...58
4.1
Introduction………………………………………………………………….58
4.2
Technical Drawing…………………………………………………………..58
4.3
Data Calculation……………………………………………………………..62
4.3.1
Bend Allowance……………………………………………………………..62
4.3.2
Bending Force……………………………………………………………….64
4.4
Report Generated by CATIA………………………………………………..69
4.5
Simulation Results…………………………………………………………..72
4.6
Safety Factor………………………………………………………………...74
CHAPTER 5 DISCUSSION…………………………………………………….…76
5.1
Bend Allowance……………………………………………………………..76
5.2
Bending forces………………………………………………………………78
5.3
Simulation………………………………………………………………...…84
5.3.1
The Simulation and Its Limitation…………………………………………..84
5.3.2
Meshing……………………………………………………………………...84
5.3.3
Von Mises Stress…………………………………………………………….86
viii
5.4
Safety Factor………………………………………………………………...87
5.5
Generated Design Rules Table for Sheet Metal Bending…………………...87
CHAPTER 6 CONCLUSION…………………………………………………..…90
REFERENCES………………………...………………………….………………..92
APPENDIX : CATIA Report for Aluminum Analysis ……………...………...95
ix
LIST OF TABLES
2.1
Compositions and Mechanical Properties for Several Common
Aluminum Alloys
2.2
12
Room Temperature Mechanical Properties (in tension) for various
Materials
15
2.3
Material Database and Derived Parameter Ranking
15
2.4
Properties of Titanium Alloys
15
2.5
Explanation for Each Term of Bending Terminology and the
Description
20
4.1
Result of the Calculation for Bend Allowance
64
4.2
Bending force for Titanium
66
4.3
Bending force for Copper
66
4.4
Bending force for Steel
67
4.5
Bending force for Aluminum
67
4.6
Bending forces for 8mm of die opening
68
4.7
Bending forces for 12mm of die opening
68
4.8
Material Properties of Copper
69
4.9
Mesh‟s Report
69
4.10
Element Type
70
4.11
Applied Load Resultant
70
x
4.12
Direct Method Computation (Equilibrium)
70
4.13
Stiffness Computation
71
4.14
The Summary of Von Mises Stress (Maximum Stress) Results
After Simulation Using CATIA for Titanium and Aluminum
74
4.15
Summary of the Results for Safety Factor
75
5.1
Design Rules Table for Sheet Metal Bending
89
xi
LIST OF FIGURES
1.1
Gantt Chart of PSM 1
6
1.2
Gantt Chart of PSM 2
7
2.1
Idealised Sheet Geometry (Left) Compared to Actual Geometry
10
2.2
Bending Terminology
20
2.3
Bend Allowance and Bend Deduction
22
2.4
Location of Neutral Line with Represents the K-factor
23
2.5
Bend Allowance
24
2.6
Volumetric Model (a), Foil Model (b), and Foil Model with
Extended Flanges (c)
2.7
27
Foil Models with Flange Extension: (a) Model with Fully Extended
Flanges and (b) Model with Limited Flange Extension
28
2.8
Press Brake Machine
29
2.9
Critical Dimension in the Design of Sheet Metal Part
32
2.10
Rules for Distance between Holes
33
2.11
Rules for Distance between Hole and Outer Edge
33
2.12
Rules between Bends and Holes
34
2.13
Angle Measurement by Mean of Shaft Encoders
34
2.14
Non-contact Angle Measurement by Means of a Reflected
xii
Laser Beam
35
2.15
Indirect Angle Measurement based on Four Contact Points
36
2.16
When Costs are Committed
49
2.17
(a) A General Two-Dimensional Domain of Field Variable Φ (X, Y),
(b) A Three-Node Finite Element Defined in the Domain, and
(c) Additional Elements Showing a Partial Finite Element Mesh
of the Domain
2.18
42
A Mesh of Finite Elements over a Rectangular Region Having a
Central Hole
45
2.19
The Forming FE Model and Schematics for Drawbead Settings
46
2.20
Deformation Path of an Element during Forming Operation
47
3.1
Methodology of Process Flow Chart
49
3.2
The Engineering Sketches for (a) Bending with One Hole,
(b) Bending with Two Holes, and (c) Bending between Two Holes
3.3
54
CAD drawing of Sheet Metal using Computer Aided Three
Dimensional Interactive Application (CATIA)
54
3.4
Restraint and Load Applied On the Part
56
4.1
Sheet Metal Bending with 90° of Bend Angle
59
4.2
Sheet Metal Bending with 60° of Bend Angle
60
4.3
Sheet Metal Bending with 45° of Bend Angle
61
xiii
4.4
Graph of the Relationship between R/T Ratio and Tensile
Reduction of Area for Sheet Metals. Figure above Shows the
Selected Ratio of R/T
63
4.5
Die opening for press brake machine with size of 8mm and 12mm
65
4.6
Von Mises Stress (nodal values) for Aluminum with 0.5mm of
Thickness
4.7
71
(a) Geometry of Sheet Metal Bending for Aluminum with 90° of
Bend Angle; and (b) Deformed Mesh for Aluminum when 100N
of Load is applied on it
4.8
72
Von Mises Stress (Maximum Stress Value) Obtained after Simulation
using CATIA for Aluminum with 0.5mm of Thickness and 90° of
Bend Angle is 4.25x107N/m2 or 4.25N/mm2
73
5.1
Graph of Bend Allowance for Every Material
77
5.2
Graph of Bending Force for Titanium
78
5.3
Graph of Bending Force for Copper
79
5.4
Graph of Bending Force for Steel
80
5.5
Graph of Bending Force for Aluminum
81
5.6
Graph of Bend Force for 8mm of Die Opening For Titanium,
Copper, Steel and Aluminum
5.7
5.8
82
Graph of Bend Force for 12mm of Die Opening for Titanium,
Copper, Steel and Aluminum
82
Mesh Elements
85
xiv
5.9
Von Mises Stress (maximum stress) predicted stress occurs in
the aluminum bending with a value of the Von Mises stress
of 4.25x107 N/m2 or 4.25x101N/mm2
xv
86
LIST OF ABBREVIATIONS AND SPECIALIZED
NOMENCLATURE
BA
-
Bend Allowance
CAD
-
Computer-aided Design
CAE
-
Computer-aided Engineering
CAM
-
Computer-aided Manufacturing
CATIA
-
Computer Aided Three Dimensional Interactive Application
Cr
-
Chromium
Cu
-
Copper
DFM
-
Design for Manufacture
FEA
-
Finite Element Analysis
FE
-
Finite Element
Mg
-
Magnesium
Mn
-
Manganese
Si
-
Silicon
Zr
-
Zirconium
xvi
LIST OF APPENDICES
Figure 1:
Boundary Conditions
96
Figure 2:
Deformed Mesh
99
Figure 3:
Von Mises Stress (nodal values)
99
xvii
CHAPTER 1
INTRODUCTION
1.1
Background of Study
Product design has been estimated that 70 to 80% of the overall costs of product and
it become the most important stage in the product development. Besides that, it is
also known as the critical stage where an innovative approach is required in order to
design and manufacture high quality products at lower costs. A thorough
understanding of the function and performance is highly desirable at this phase. The
product design has to follow the rules to meet the specification to avoid encountering
problems during manufacturing process which is only wasting the time and costs
from redesigning the product. Therefore a specific rule is an essential in designing
and manufacturing products.
Sheet metal can be simply shaped into thin and flat pieces. There a variety of types of
metals made into the sheet metal such as aluminum, brass, copper, and nickel.
Nowadays, sheet metal has applications in producing car bodies and air plane. It can
be cut and bend. The most common operation in industrial forming of sheet metal is
bending. In this operation, metal is plastically deformed and its shape is changed.
Basically, the material is stressed beyond its yield strength and below the ultimate
1
tensile strength from bending operation. However, it involves little changes on the
material surface area.
Generally, the bending referred to the deformation is on only one axis. A various and
different shape can be produced in implementing bending process by using standard
die sets. The material needed to bend is placed on the die and positioned it in place
with gages. It is held in place with hold-downs. In manufacturing, the bending
process includes press brake, air bending and bottoming or coining.
Finite Element Analysis (FEA) software and Computer-Aided Design (CAD) are
tool that can help to simultaneously analyze and simulates parts or products from a
variety of functional perspectives and also increases product performance and
product quality. At the same time, manufacturing cost is reduced. These tools also
will also guide part designers to decide the appropriate factors of design. By
implementing the software to this study, the bending part is produced with great
consistency, accuracy and less time.
In this study, the Design for Manufacture (DFM) is used to improve the design for
the bending process. Design for manufacture is a step towards integrating
manufacturing and the design processes. Design for manufacture also concerns the
cost and complexity of making the product. It is a proven design methodology that
works for any company. For DFM to work, designers must know how to actually
design products that are manufacturability. Experience in manufacturing is an
essential for optimal design, but designers who don‟t have this experience are at a
loss while designing new components. A good DFM program will aid designers
through the design process (Boothroyd et al. 2002).
2
1.2
Problem Statement
Design is a crucial stage in product development. It is because the product
performance, product quality and final cost of product are more influence in this
stage. Therefore, following the rules that meet the specification only can produce a
high quality product. However, there is lack of communication between the designer
and manufacturer. This typical manufacturing situation must be avoided. In order to
perform an efficient manufacturing process, the knowledge of manufacturing in
industry must be sharing together from design stage to manufacture the product. The
expert design engineer only design the product based on experiences and knowledge
but not well-documented. In contrast, the new designers who have no experience will
encounter the problems in designing new parts or products and directly it will
increase time and cost of manufacturing. Therefore, it is necessary to generate design
rules for sheet metal.
1.3
Objectives of PSM
(a)
To investigate the design parameters of sheet metalworking.
(b)
To analyze the design rules of sheet metalworking that influence
bending operation.
(c)
To generate the design rules for sheet metalworking.
3
DESIGN RULES ANALYSIS FOR SHEET METALWORKING
USING CAD TOOLS
This report submitted in accordance with requirement of the Universiti Teknikal
Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering
(Manufacturing Design) with Honours.
by
SHALIZAH AMAN SHAH
FACULTY OF MANUFACTURING ENGINEERING
April 2009
DECLARATION
I hereby, declared this report entitled “Design Rules Analysis for Sheet
Metalworking Using CAD Tools” is the results of my own research except as cited in
references.
Signature
:
…………………………………………..
Author‟s Name
:
…………………………………………..
Date
:
…………………………………………..
APPROVAL
This report is submitted to the Faculty of Manufacturing Engineering of UTeM as a
partial fulfillment of the requirements for the degree of Bachelor of Manufacturing
Engineering (Manufacturing Design) with Honours. The member of the supervisory
committee is as follow:
(Signature of Supervisor)
……………………………
(Official Stamp of Supervisor)
ABSTRACT
Sheet metal design is a critical part in the process of product design and
development. The entire quality of design influences the product performance,
product quality and cost of product. An optimal design can only be created based on
experiences and knowledge. The problem of frequent redesign occurs due to have no
well-documented rules in designing of sheet metalworking. The study of this project
is to investigate the design parameters of sheet metalworking and analyze the design
rules of sheet metal that influences the bending operation. Computer-Aided Design
(CAD) and Finite Element Analysis (FEA) are applied in this study in order to
design of safety factor and simulate the structural of bending parts. Bend allowance
has strong relationship to determine the safe area in designing of sheet metalworking.
As a result, a comprehensive set of design rules for sheet metal parts has been
generated and assisted in reducing an infeasible design, cost and production cycle
time.
Keyword: Bend Allowance, CAD, Design Rules, FEA, Sheet Metal.
i
ABSTRAK
Rekabentuk kepingan logam merupakan komponen yang kritikal dalam proses
rekabentuk dan pembangunan produk. Hal ini kerana kualiti sesuatu rekabentuk
secara keseluruhannya akan mempengaruhi kebolehgunaan produk, kualiti produk
dan kos produk. Oleh yang demikian, peraturan rekabentuk memainkan peranan
penting pada peringkat ini. Masalah yang terjadi dalam industri ialah tiada peraturan
yang didokumenkan secara formal. Rekabentuk yang optimum hanya boleh
dihasilkan berdasarkan pada pengalaman dan pengetahuan semata-mata. Projek ini
mengkaji tentang parameter-parameter rekabentuk kepingan logam dan menganalisis
peraturan rekabentuk kepingan logam yang mempengaruhi proses bending. Perisian
Computer-aided Design (CAD) dan Finite Element Analysis (FEA) diaplikasikan
dalam projek ini untuk merekabentuk faktor keselamatan dan mengsimulasi
struktural bahagian bending. Manakala bend allowance pula berkait rapat bagi
menentukan bahagian yang selamat dalam merekebentuk kompenan atau produk
kepingan logam. Pada penghujung projek ini, satu set peraturan rekabentuk kepingan
logam yang komprehensif dibentuk dan ianya dapat membantu mengurangkan
rekebentuk, kos dan kitaran masa pengeluaran yang tidak relevan.
Kata kunci: Kepingan Logam, Peraturan Rekabentuk, Proses bending, FEA, CAD
tools.
ii
DEDICATION
For my dearest mom and dad.
iii
ACKNOWLEDGEMENT
This research was performed under the supervision of Mr. Taufik, whom I like to
thank for the freedom granted in carrying out this project. I also would like to
express my deepest appreciation for Mr. Taufik in understanding regarding
difficulties I had during the project. Not forgetting to gratefully acknowledge to Mr.
Sapto Wahyono Widodo in spending his time for consultation according to Finite
Element Analysis (FEA). I would like to express my appreciation to Mr. Abdul
Halim Hakim Bin Abdul Aziz and Mr. Amri Bin Sulaiman for being my panels and
that they spend time to evaluate my report. A special thanks to all my friends and
others who had work together in assisting my project, I could not achieve it without
their support and encouragement. Last, but certainly not least the continual support
and patience of my parents is deeply and sincerely appreciated.
iv
TABLE OF CONTENTS
ABSTRACT……………………………………………………………………...……i
ABSTRAK……………………………………………………………………...…….ii
DEDICATION…………………………………………………………………...…..iii
ACKNOWLEDGEMENT………………………………………………………..….iv
TABLE OF CONTENTS……………………………………………………...……...v
LIST OF TABLES…………………………………………………………...……….x
LIST OF FIGURES…………………………………………………………..……..xii
LIST OF ABBREVIATIONS AND SPECIALIZED NOMENCLATURE……......xvi
LIST OF APPENDICES…………………………………………………….……..xvii
CHAPTER 1 INTRODUCTION…………………..….……………………………1
1.1
Background of Study………………………………..………………..…...….1
1.2
Problem Statement…………………………………………..………………..3
1.3
Objective of PSM……………………………………………………...…..….3
1.4
Scope of Work…………………………………………………….....……….4
1.5
Schematic of Project……………………………………………………....….4
1.6
Gantt Chart…………………...…………………………………...…………..5
CHAPTER 2 LITERATURE REVIEW……...…………………………….…...…8
2.1
Introduction…………………………………...………………...…………….8
v
2.2
Sheet Metalworking……………………………………..………………..…..8
2.2.1
Sheet Metal Forming Process……………………………………………..….9
2.2.2
Determining material properties of sheet metal on a press brake………...…10
2.2.3
Type of Sheet Metalworking…………………………………………......…11
2.2.3.1 Aluminum Alloys………………………………………......……………..…11
2.2.3.2 Copper……………………………………………...………………………..13
2.2.3.3 Steel………………………………………………...………………………..13
2.2.3.4 Titanium ……...……………………………………………………..…....…14
2.3
Material Properties…………………………………………………………..16
2.3.1
Tensile Strength……………………………………………………………..16
2.3.2
Fatigue…………………………………………..…………...………..……..16
2.4
Design for Sheet Metalworking………………………………...…………...17
2.5
Bending…………………………………………….....…………….……….18
2.5.1
Sheet Metal Bending…………………………………………..…...….…….19
2.5.2
Bending Terminology……………………………………………..……...…19
2.5.3
Bend Allowances………………………………………………..…………..21
2.5.4
Bending Force……………………………………………………………….25
2.5.5
Bending Models……………………………………………………...……...26
2.5.6
Computer aided process planning for sheet metal bending:
A state of the art…………………………………………………………….27
2.6
Press Brake……………………………………………………...…………...28
2.6.1
Press Brake Operations……………………………………………..…...…..30
2.6.2
Structural Analysis and Optimisation of Press Brakes…………………...…30
vi
2.7
Design Rules……………………..………………………………………….31
2.7.1
Inter-features Rules…………………………………………...…………..…32
2.8
Mathematical Modeling…………………………………………..……..…..34
2.9
Computer-aided Design (CAD)………………………………………..……36
2.10
Design for Manufacture (DFM)………………………………………..……37
2.11
Finite Element Analysis (FEA)………………………………………......….39
2.11.1 Introduction to Finite Element Analysis (FEA)…………………...……...…39
2.11.2 General Techniques and Terminology of FEA……………………...…...….41
2.11.3 A General Procedure for Finite Element Analysis………………..…...……43
2.11.3.1Preprocessing………………………..……………………………..……….43
2.11.3.2Solution………………………..……………………………………………44
2.11.3.3Postprocessing……………………...………………………………….……44
2.11.4 Example of Finite Element Analysis (FEA)…………………………….…..45
2.11.5 Finite Element (FE) Modeling………………………………..………….….46
2.11.6 Deformation Path………………………………………..……………….….47
CHAPTER 3 METHODOLOGY AND MATERIALS…………………….…....48
3.1
Introduction…………………………...………………………………..……48
3.2
Methodology…………………………..……………………….……………48
3.3
Description of the Methodology………………………..……………..…….50
3.4
Method to Conduct a CATIA simulation……………………………………55
3.4.1
Creation of the Part in Generative Sheet Metal Design……………………..55
3.4.2
Entering the Analysis Solutions……………………………………………..55
vii
3.4.2.1 Step 1: Mesh Generation…………………………………………………….55
3.4.2.2 Step 2: Assigning Material Properties……………………………………....55
3.4.2.3 Step 3: Applying Restraint and Load………………………………………..56
3.4.2.4 Step 4: Launching the Solver………………………………………………..57
3.4.2.5 Step 5: Postprocessing…………………………………………………...….57
CHAPTER 4 RESULTS…………………………………………………………...58
4.1
Introduction………………………………………………………………….58
4.2
Technical Drawing…………………………………………………………..58
4.3
Data Calculation……………………………………………………………..62
4.3.1
Bend Allowance……………………………………………………………..62
4.3.2
Bending Force……………………………………………………………….64
4.4
Report Generated by CATIA………………………………………………..69
4.5
Simulation Results…………………………………………………………..72
4.6
Safety Factor………………………………………………………………...74
CHAPTER 5 DISCUSSION…………………………………………………….…76
5.1
Bend Allowance……………………………………………………………..76
5.2
Bending forces………………………………………………………………78
5.3
Simulation………………………………………………………………...…84
5.3.1
The Simulation and Its Limitation…………………………………………..84
5.3.2
Meshing……………………………………………………………………...84
5.3.3
Von Mises Stress…………………………………………………………….86
viii
5.4
Safety Factor………………………………………………………………...87
5.5
Generated Design Rules Table for Sheet Metal Bending…………………...87
CHAPTER 6 CONCLUSION…………………………………………………..…90
REFERENCES………………………...………………………….………………..92
APPENDIX : CATIA Report for Aluminum Analysis ……………...………...95
ix
LIST OF TABLES
2.1
Compositions and Mechanical Properties for Several Common
Aluminum Alloys
2.2
12
Room Temperature Mechanical Properties (in tension) for various
Materials
15
2.3
Material Database and Derived Parameter Ranking
15
2.4
Properties of Titanium Alloys
15
2.5
Explanation for Each Term of Bending Terminology and the
Description
20
4.1
Result of the Calculation for Bend Allowance
64
4.2
Bending force for Titanium
66
4.3
Bending force for Copper
66
4.4
Bending force for Steel
67
4.5
Bending force for Aluminum
67
4.6
Bending forces for 8mm of die opening
68
4.7
Bending forces for 12mm of die opening
68
4.8
Material Properties of Copper
69
4.9
Mesh‟s Report
69
4.10
Element Type
70
4.11
Applied Load Resultant
70
x
4.12
Direct Method Computation (Equilibrium)
70
4.13
Stiffness Computation
71
4.14
The Summary of Von Mises Stress (Maximum Stress) Results
After Simulation Using CATIA for Titanium and Aluminum
74
4.15
Summary of the Results for Safety Factor
75
5.1
Design Rules Table for Sheet Metal Bending
89
xi
LIST OF FIGURES
1.1
Gantt Chart of PSM 1
6
1.2
Gantt Chart of PSM 2
7
2.1
Idealised Sheet Geometry (Left) Compared to Actual Geometry
10
2.2
Bending Terminology
20
2.3
Bend Allowance and Bend Deduction
22
2.4
Location of Neutral Line with Represents the K-factor
23
2.5
Bend Allowance
24
2.6
Volumetric Model (a), Foil Model (b), and Foil Model with
Extended Flanges (c)
2.7
27
Foil Models with Flange Extension: (a) Model with Fully Extended
Flanges and (b) Model with Limited Flange Extension
28
2.8
Press Brake Machine
29
2.9
Critical Dimension in the Design of Sheet Metal Part
32
2.10
Rules for Distance between Holes
33
2.11
Rules for Distance between Hole and Outer Edge
33
2.12
Rules between Bends and Holes
34
2.13
Angle Measurement by Mean of Shaft Encoders
34
2.14
Non-contact Angle Measurement by Means of a Reflected
xii
Laser Beam
35
2.15
Indirect Angle Measurement based on Four Contact Points
36
2.16
When Costs are Committed
49
2.17
(a) A General Two-Dimensional Domain of Field Variable Φ (X, Y),
(b) A Three-Node Finite Element Defined in the Domain, and
(c) Additional Elements Showing a Partial Finite Element Mesh
of the Domain
2.18
42
A Mesh of Finite Elements over a Rectangular Region Having a
Central Hole
45
2.19
The Forming FE Model and Schematics for Drawbead Settings
46
2.20
Deformation Path of an Element during Forming Operation
47
3.1
Methodology of Process Flow Chart
49
3.2
The Engineering Sketches for (a) Bending with One Hole,
(b) Bending with Two Holes, and (c) Bending between Two Holes
3.3
54
CAD drawing of Sheet Metal using Computer Aided Three
Dimensional Interactive Application (CATIA)
54
3.4
Restraint and Load Applied On the Part
56
4.1
Sheet Metal Bending with 90° of Bend Angle
59
4.2
Sheet Metal Bending with 60° of Bend Angle
60
4.3
Sheet Metal Bending with 45° of Bend Angle
61
xiii
4.4
Graph of the Relationship between R/T Ratio and Tensile
Reduction of Area for Sheet Metals. Figure above Shows the
Selected Ratio of R/T
63
4.5
Die opening for press brake machine with size of 8mm and 12mm
65
4.6
Von Mises Stress (nodal values) for Aluminum with 0.5mm of
Thickness
4.7
71
(a) Geometry of Sheet Metal Bending for Aluminum with 90° of
Bend Angle; and (b) Deformed Mesh for Aluminum when 100N
of Load is applied on it
4.8
72
Von Mises Stress (Maximum Stress Value) Obtained after Simulation
using CATIA for Aluminum with 0.5mm of Thickness and 90° of
Bend Angle is 4.25x107N/m2 or 4.25N/mm2
73
5.1
Graph of Bend Allowance for Every Material
77
5.2
Graph of Bending Force for Titanium
78
5.3
Graph of Bending Force for Copper
79
5.4
Graph of Bending Force for Steel
80
5.5
Graph of Bending Force for Aluminum
81
5.6
Graph of Bend Force for 8mm of Die Opening For Titanium,
Copper, Steel and Aluminum
5.7
5.8
82
Graph of Bend Force for 12mm of Die Opening for Titanium,
Copper, Steel and Aluminum
82
Mesh Elements
85
xiv
5.9
Von Mises Stress (maximum stress) predicted stress occurs in
the aluminum bending with a value of the Von Mises stress
of 4.25x107 N/m2 or 4.25x101N/mm2
xv
86
LIST OF ABBREVIATIONS AND SPECIALIZED
NOMENCLATURE
BA
-
Bend Allowance
CAD
-
Computer-aided Design
CAE
-
Computer-aided Engineering
CAM
-
Computer-aided Manufacturing
CATIA
-
Computer Aided Three Dimensional Interactive Application
Cr
-
Chromium
Cu
-
Copper
DFM
-
Design for Manufacture
FEA
-
Finite Element Analysis
FE
-
Finite Element
Mg
-
Magnesium
Mn
-
Manganese
Si
-
Silicon
Zr
-
Zirconium
xvi
LIST OF APPENDICES
Figure 1:
Boundary Conditions
96
Figure 2:
Deformed Mesh
99
Figure 3:
Von Mises Stress (nodal values)
99
xvii
CHAPTER 1
INTRODUCTION
1.1
Background of Study
Product design has been estimated that 70 to 80% of the overall costs of product and
it become the most important stage in the product development. Besides that, it is
also known as the critical stage where an innovative approach is required in order to
design and manufacture high quality products at lower costs. A thorough
understanding of the function and performance is highly desirable at this phase. The
product design has to follow the rules to meet the specification to avoid encountering
problems during manufacturing process which is only wasting the time and costs
from redesigning the product. Therefore a specific rule is an essential in designing
and manufacturing products.
Sheet metal can be simply shaped into thin and flat pieces. There a variety of types of
metals made into the sheet metal such as aluminum, brass, copper, and nickel.
Nowadays, sheet metal has applications in producing car bodies and air plane. It can
be cut and bend. The most common operation in industrial forming of sheet metal is
bending. In this operation, metal is plastically deformed and its shape is changed.
Basically, the material is stressed beyond its yield strength and below the ultimate
1
tensile strength from bending operation. However, it involves little changes on the
material surface area.
Generally, the bending referred to the deformation is on only one axis. A various and
different shape can be produced in implementing bending process by using standard
die sets. The material needed to bend is placed on the die and positioned it in place
with gages. It is held in place with hold-downs. In manufacturing, the bending
process includes press brake, air bending and bottoming or coining.
Finite Element Analysis (FEA) software and Computer-Aided Design (CAD) are
tool that can help to simultaneously analyze and simulates parts or products from a
variety of functional perspectives and also increases product performance and
product quality. At the same time, manufacturing cost is reduced. These tools also
will also guide part designers to decide the appropriate factors of design. By
implementing the software to this study, the bending part is produced with great
consistency, accuracy and less time.
In this study, the Design for Manufacture (DFM) is used to improve the design for
the bending process. Design for manufacture is a step towards integrating
manufacturing and the design processes. Design for manufacture also concerns the
cost and complexity of making the product. It is a proven design methodology that
works for any company. For DFM to work, designers must know how to actually
design products that are manufacturability. Experience in manufacturing is an
essential for optimal design, but designers who don‟t have this experience are at a
loss while designing new components. A good DFM program will aid designers
through the design process (Boothroyd et al. 2002).
2
1.2
Problem Statement
Design is a crucial stage in product development. It is because the product
performance, product quality and final cost of product are more influence in this
stage. Therefore, following the rules that meet the specification only can produce a
high quality product. However, there is lack of communication between the designer
and manufacturer. This typical manufacturing situation must be avoided. In order to
perform an efficient manufacturing process, the knowledge of manufacturing in
industry must be sharing together from design stage to manufacture the product. The
expert design engineer only design the product based on experiences and knowledge
but not well-documented. In contrast, the new designers who have no experience will
encounter the problems in designing new parts or products and directly it will
increase time and cost of manufacturing. Therefore, it is necessary to generate design
rules for sheet metal.
1.3
Objectives of PSM
(a)
To investigate the design parameters of sheet metalworking.
(b)
To analyze the design rules of sheet metalworking that influence
bending operation.
(c)
To generate the design rules for sheet metalworking.
3