Design and simulation of die and punch for sheet metal on bending.
SUPERVISOR DECLARTION
"I hereby declare that I have read this thesis and in my opinion this report is
sufficient in terms of scope and quality for the award of the degree of Bachelor of
Mechanical Engineering (Design & Innovation)"
Signature:
Supervisor:
Date:
.'X?... ｾ＠
.. ｾｊ＠
© Universiti Teknikal Malaysia Melaka
..
II
DESIGN AND SIMULATION
OF DIE AND PUNCH FOR SHEET METAL ON BENDING
NEOH THIAM HWA
This report is submitted in fulfillment of the requirements for the award
Bachelor of Mechanical Engineering (Design & Innovation)
Fakulti Kejuruteraan Mekanikal
Universiti Teknikal Malaysia Melaka
JUNE 2013
© Universiti Teknikal Malaysia Melaka
Ill
DECLARATION
"I hereby declare that the work in this report is my own except for summaries and
quotations which have been duly acknowledged. "
Signature:
ﾷ ﾷ ｾﾷ
ﾷ ﾷ ﾷ ﾷ ﾷ＠
Author:
NEOH THIAM HWA
Date:
Ｎｾ＠
...ｗＮｾ
ｎｾ＠
.. ｾＱＵ＠
© Universiti Teknikal Malaysia Melaka
IV
I dedicate this report to my loving mom, Madam Tan Cheok Tang, who also happens
to be my best friend . She is been my main supporter all these years. She instilled in
me a sense of curiosity about life and a thirst for knowledge. Besides, I would like to
take this opportunity to thank all of the people whose time, efforts and help were
given in order to help me complete this report on time. Furthermore, I want to thanks
all the staff in UTeM especially the lecturer and technicians in FKM to make my
PSM undergo smoothly and successfully. Thank you.
© Universiti Teknikal Malaysia Melaka
v
ACKNOWLEDGEMENT
First of all, I would like to thank sincerely to my supervisor, Dr Hady Efendy
for spending his precious time in guiding me with his expertise and giving his moral
support. The countless time that he spent in reflecting, encouraging, and advising
patiently throughout the entire process help me a lot in finishing this project. I have
learned many from him and gained my confidence from the project.
Secondly, I would also like to thank to En. Wan Farid for providing the
information and help for me regarding to the project. Without his help, I would not
able to complete my project successfully. Besides, special thanks to the staffs and
technicians in FKM for providing the assistance regarding with my request.
Last but not least, I would like to thank to all my friends for the
understanding and encouragement during my project.
Thank you.
© Universiti Teknikal Malaysia Melaka
VI
ABSTRAK
Proses lembaran logam lentur adalah satu proses dimana daya tekanan
dikenakan atas sekeping logam dalam usaha untuk mengubah struktur geometrinya.
Daya tekanan menyebabkan kepingan logam membengkok pada sudut yang
dikehendaki diantara penumbuk dan bekas. Waiau bagaimanapun, kecacatan
biasanya berlaku semasa proses lembaran menyebabkan kepingan logam calar,
kepesongan dan perubahan dalam ciri-ciri fizikal kepingan logam. Oleh itu, bekas
dan penumbuk kepingan logam direka dan dibangunkan dengan menggunakan
SolidWorks untuk meminimumkan kecacatan itu berlaku. Selepas itu, analisis unsur
terhingga (FEA) dengan perisian computer komersial, ANSYS digunakan untuk
memberi simulasi pembengkokan kepingan logam. Selepas itu, keputusan daripada
simulasi dibandingkan dengan keputusan eksperimen yang sedia ada. Ini kerana
terdapat perbezaan antara sirnulasi dengan eksperimen hasil daripada perbezaan
keadaan yang sebenar dengan keadaan yang ideal. Selain itu, kajian pembolehubah
prinsip lenturan lembaran logam juga dijalankan. Pembolehubah ini termasuk
perubahan mekanik seperti ketegangan, tekanan, dan penumpuan daya tekanan dalam
kepingan logam.
© Universiti Teknikal Malaysia Melaka
VII
ABSTRACT
Sheet metal bending processes is a process which force is applied on a piece
of sheet metal in order to modify its geometry structure. The force causing it to bend
at desired angle and shape between die and punch. However, defect during the
bending process cause by die and punch such as scratching, high percentage of
deflection and changes in the physical characteristic of the sheet metal usually occur.
Hence, the die and punch for sheet metal bending is being designed and developed
by using SolidWorks in order to minimize the defect occurs. Following by that, finite
element analysis (FEA) with commercial software, ANSYS, computer basedsimulation is being used to simulate the sheet metal bending. After that, the results
from the simulation are compared with the existing U-bending experiment results
due to the differences between real life conditions and ideal conditions. Besides, the
study of the principle variables of the sheet metal bending is being carried out. These
variables include mechanics of deformation such as stress, strain and force
concentration in the sheet metal.
© Universiti Teknikal Malaysia Melaka
VIII
TABLE OF CONTENTS
DECLARATION ..................................................................................................... III
DEDICATION .......................................................................................................... IV
ACKNOWLEDGEMENT ........................................................................................ V
ABSTRAK ................................................................................................................ VI
ABSTRACT ............................................................................................................ VII
CHAP'fER 1: INTRODUCTION ............................................................................. 1
I .O
INTRODUCTION .......... .. ..... ...... ...... ..................... ... ...... ........ .. ...... ... ........ ... I
I.I
SHEET METAL FORMING .. ... ........... ............... .. ... ... ... ... ...... ...... ....... .... .. .. I
I.I.I
Bending .. ... .. ........ .. ... ..... ... ...... ... ..... ...... .. .. ... .... ... ... .... .. .. ....... ... .. .. .... ... .... 3
I. I .2
Die and punch .......... .. .. ....... .... ... ......... .......... ........ ....... ............ .. .... .. ...... 4
I. I .3
FEA Simulation ..... ....... ... .... .. ..... .. .... .... ... .... ... ......... ... .. ... ..... ..... ..... .... .. .. 5
I .2
OBJECTIVE .. ..... ...... .... .... ........ ... ........ ..... ... .. .... ..... .... ....... ...... .... .. .... .... ...... .. 5
I .3
SCOPE ....... .. .. ..... ...... ..... .... .. ..... .... ... ... ...... ...... ... .... ..... .... .... .... ... ...... ..... ....... .. 5
I .4
PROBLEM STATEMENT ... ... ... .. .. .... ... ...... .... ....... ... .... .... .... ... .. .. ... .... ....... .. 6
I .5
FLOW CHART ... ..... ..... .... .......... ...... ..... ........ .. ..... .. ... .... .... .............. ...... ....... 7
CHAP'fER 2: LITERATURE REVIEW ................................................................. 8
2.0
INTRODUCTION TO BENDING PROCESS .. .............. .. ........... ... .... ......... 8
2. I
SHEET MET AL BENDING PARAMETERS ...... ....... ........ .... ... .... .. .. .... ..... 8
2.2
SPRINGBACK ... .. ....... .... .... .... .... ... ......... ...... ... ... .. .... .... ........ ... .... .... .. .... ... .. I l
2.3
THE CRYSTAL STRUCTURE OF METALS ..... ........ ........... ...... .. .. ........ . I2
2.4
THE PRACTICE OF U-SHAPE SPECIMEN ... ....... ............. ... ......... ......... 13
2.5
SIGNIFICANCE AND USE OF U-BEND SPECIMEN ... .... ....... ..... ...... ... I3
2.6
THE TEST SPECIMEN ................ .......... ... .... .... .... .. .. .... ....... ....... ..... ......... . 14
2.7
STRESS CONSIDERATIONS IN U-BEND SPECIMEN .. .. .. ...... .. ........... I6
© Universiti Teknikal Malaysia Melaka
IX
2.8
STRESSING THE U-BEND SPECIMEN .................... .... ...... .. ........... ...... . 16
2.9
EXPOSURE OF THE TEST SPECIMEN .... ....... ..................... .... ... ..... ...... 19
2.10
METHOD OF PRESSURE BENDING .... ........ .. .. ........ ...... .. .. .................... 19
2.11
FINITE ELEMENT ANALYSIS OF U-BEND ....... .... .............................. . 21
2.12
THE FEM SIMULATION RESULTS AND DISCUSSION ............. ....... .. 22
CHAP'fER 3: METHODOLOGY .......................................................................... 24
3.0
INTRODUCTION .. ........ ..... .................... .... ....... ...... ... ....... ............. .. ...... .. .. 24
3.1
INFORMATION GATHERING .......... ..... .. ...... ................ .... ...... .. .... .... .. .... 25
3.2
PROBLEM IDENTIFICATION .... ........ .... .... ................ ...... .. ...... .... .... .. ..... 25
3.3
PRODUCT DESIGN SPECIFICATION ............................ .... .......... ... ..... .. 26
3.3.1
Product Identification ............ .. .... ............ ................... .. .............. .. ........ 26
3.3.2
Key Project Deadlines ......... ... ...... .. ..... ... ...... .... .... ... .. ...... ..... ... .... .... .... . 26
3.3.3
Physical Description ... .................... ....... ........ ... ........... ... ......... ... .......... 26
3.4
CONCEPT GENERATION ..... ..... .......................... .. ...... ................ .. .... ...... 27
3.4.1
House of Quality ........... ........ .... ..... .. ............... .. ....... .. ..... ...... ...... ..... ... .. ... 27
3.4.2
Morphological Chart .. ............. ................................. .............................. .. 30
3.5
CONCEPT SELECTION ......... .. .................................. ...... ............ .... .. ....... 32
3.5 .1
Objective Tree ..... ....... ..... ...... .... ............ .. ........ ... ....... .. ... .... ..... .... ............. 33
3.5.2
Weighted Decision Matrix ...... .... .. ....... ..... .... ... ....... ................. .. .... .... ...... 35
3.6
CONCEPTUAL DESIGN .... .. ..... .. .... .... ........................... .. ...... .... ....... ..... ... 37
3.7
SIMULATION ........ ........ ... ........ .... ... ..... .... .... ................... ... ..... .... ... .... ...... . 38
3.8
GANTT CHART ..... ........ ... .... ... .... .... ...... .. .... ........ ..... ...... .... .... .... .... .... .. ..... 42
CHAP'fER 4: DESIGN ........................................................................................... 44
4.0
DETAIL ORAWING .. ............................. .... ...... ............ .. ,, ............... ..... ..... 44
CHAP'fERS: RESULT ANDDISCUSSION ........................................................ 51
5.0
DIE AND PUNCH SIMULATION RESULTS ............ ...... .... ...... .. .... ........ 51
5.1
BENDING PROCESS IN THE EXPERIMENT .... ...... ........ .. .. ...... .... ........ 53
5.2
SHEET METAL SIMULATION RESULTS ...... .... ............ .. ...... .... ..... .. ..... 55
© Universiti Teknikal Malaysia Melaka
x
CHAPTER 6: CONCLUSION ................................................................................ 60
REFERENCES ..... .... ........ ...... ... ......... ........... .... ..... ................. .......... ......... ..... .... ....... 61
APPENDIX A: ASSEMBLY VIEW ....... ..... ... .. ... .. ..... ... ............. .......... ....... ... ....... ... 61
APPENDIX B: PUNCH ... ..... .. .............. ........ ............. .... .................. .... ......... ... ..... ..... 64
APPENDIX C: DIE ............ .... .... ..... .. .... ....... ... ..... ........... ......... ... ....... .......... ........ ... .. 65
A PPENDIX D: SLIDING GUIDE ................. ...... ....... ........ .. .. ...... .............. .. ..... ..... ... 66
© Universiti Teknikal Malaysia Melaka
XI
LIST OF TABLES
Table 2.1: Bending Characteristic ... ....... .. ... .... ... .. ......... .. .... ... ........... ... ...... ...... ... ........ . 9
Table 2.2: Bending parameters (Source: CustomPartNet, 2009) ............ ...... ... ....... ... l 0
Table 2.3: Typical U-Bend specimen dimensions ... ... .... ......... .... .... ..... ...... ..... ....... ... l 5
Table 3.1: House of Quality (HOQ) .... ... .... .. .. ....... ... ...... .......... ........ ......... .. ........... .. .. 29
Table 3.2: Morphological Chart ........... .. ....... ....... ............... ........... ........ .. ... ....... ... ..... 31
Table 3.3: Evaluation scheme for design alternatives or objectives ........ .... ... ... .. .... .. 35
Table 3.4: Weighted Decision Matrix .. ....... .. .... ........ ..... ...... ........ .. ..... .... .. ....... ........ .. 36
Table 3.5: Gantt chart of PSM l .. ...................... .. ....... ...... ... .... ............. .. ....... ........ .... 42
Table 3.6: Gantt chart of PSM 2 ...... .... ...... .. ...... .... ............. ............ .......... ................. 43
Table 5.1: Comparison between existing results of experiment and the simulation
results .................................... ...... ... .. ... ....... .. ........ .... ...... ............... ................. ........ .. .. 57
© Universiti Teknikal Malaysia Melaka
XII
LIST OF FIGURES
Figure l . l: Bending Stresses ............... ... .. ...... ... ... ........ .... .. .... ....... ... .. ....... .... ....... .... .... 4
Figure 1.2: Sheet metal bending .... .. .... .... ... .... ... ..... ...... ......... ... .... ....... .. .... .... ..... ....... ... 4
Figure 2. l: Bending diagram ...... ........ ......... ... .... .. ......... .... ...... .... .... .. ... ... ........ ...... ... .... 8
Figure 2.2: Neutral axis ... .. ... ....... .... ..... ... ... ... ....... ... ....... ......... .... .... ..... .... .... .... ..... ..... 10
Figure 2.3: Springback .... .. ... ... .... ...... ...... ... ..... ... ......... .. ... ...... .. .. .. .......... .... .. .... .... .... .. 11
Figure 2.4: Crystal structure of metals: (a) the body-centered cubic; (b) the facecentered cubic; (c) the hexagonal close-packed ... ........ ............. ... ... ....... ..... ... ....... .... . 12
Figure 2.5: Typical Stressed U-bends ...... .... ........ ...... .. ....... .. ..... ............ ...... .. .. .. ... ..... 13
Figure 2.6: Method of stressing U-Bend specimen - One stage stressing ......... .. .... .. 17
Figure 2. 7: Method of stressing U-Bend - Two stage method ... .... .... ......... .. .... ....... .. 18
Figure 2.8: True sress-true strain relationships for stressed U-Bends ... ... ... ......... ..... 18
Figure 2.9: Bending action- pressure bending ... ........ ... .... .. .......... ... ... ...... .. .......... ..... 19
Figure 2. l 0: Two methods of pressure bending. (a) Air bending; (b) Pressure bending
... ... ........... ... ........ ...... ... ... ................................... ................ .... .... .......... ..... ... .............. . 20
Figure 2.11: Precision U-bending models. (a) Without the coined bead. (b) With the
coined bead .... ........ ......... ... ...... ........... .... .... .. ....... .. ......... ... .... ........ .......... .. .... ....... .. .... 21
Figure 2.12: Stress distribution analysis in the workpiece and the spring-back/springgo featrue. (a) 90° (b)60° ....... .... .... ...... ... ...... .... ...... ........... ...... .... .. ... .. ..... ... .... ... .... ..... 23
Figure 3.1: Flow chart of Methodology ... ... ..... ....... .. .... .... ... ............. ...... ... ..... ......... .. 24
Figure 3.2: Objective tree for the die and punch ..... ......... ..... ........ ... .................. ........ 34
Figure 3.3: Conceptual design of die and punch ... ..... ..... .. .. .......... ... ｾ＠ ....... ...... ......... ... 37
Figure 3.4: Fixed geometry of die .... .... ... .... .... .... .... .... ........ ... .. ....... ... .... ...... ... .... ....... 39
Figure 3.5: Force applied on the die ........ .... ...... ..... ... ... ... .. ... ........... .. ...... ... ..... ........ ... 39
Figure 3.6: Fixed geometry of punch ..... ........ ... ... .... ....... .. ... ........ .... ... .. ...... ......... ... ... 39
Figure 3.7: Force applied on the punch ... ... ....... ... ... .... .... .. ........ ... ........ ......... .... .. ....... 39
Figure 3.8: The dimension of the Stainless Steel 316L sheet metal ..... ... .... ... ..... .... .. 40
Figure 3.9: The Displacement (punch) and Fixed Support (die) with the sheet metal
on the middle .... ..... ...... ... ...... ... ..... ........... ... .... ...... ..... .. ...... ..... ..... .... ............... ..... ...... . 41
© Universiti Teknikal Malaysia Melaka
XIII
Figure 3.10: Mesh generated on the die, punch and sheet metal ... ........ ... ...... ...... .... . 41
Figure 4.1: Exploded view of die and punch ..... .... ............. ... .. ..... ........... ......... ......... 44
Figure 4.2: Third angle projection (assembly) of die and punch ..... ..... ... ............ ...... 45
Figure 4.3: Third angle projection of die ...... .. ..... .. ...... ........ ......... .... .... ... .... ... ........... 46
Figure 4.4: Third angle projection of punch ...... .. ......... .... ........ ...... .. .... ... .... .... .. ....... . 47
Figure 4.5: Third angle projection of sliding guide ....... ... ... .. .... ...... ....... .... ..... ........ .. 48
Figure 4.6: Third angle projection of washer M8 ..... ... .... ...... ...... ............ ..... ......... .... 49
Figure 4.7: Third angle projection of hex cap screw M8 .. ...... ...... .. .. .. .... ... ........ ... ... .. 50
Figure 5.1 : Static displacement of die .. ........... ................. ..... .. ................ .......... ......... 51
Figure 5.2: Static displacement of punch ...... .. .. .... .... ........ .. ..... .......... ....... ... ........ ... ... 52
Figure 5.3: Die and punch installed in the Universal Testing Machine ....... ..... .. .. ..... 53
Figure 5.4: Bending process of sheet metal .. ......... .. ..... ..... ..... .. .. ...... ........ ..... ... ... .... .. 54
Figure 5.5: Simulation result of sheet metal bending with thickness 0.6mm ...... .. .... 55
Figure 5.6: Stress distribution on the U-bend sheet metal .... ....... ..... ....... .. .......... ...... 56
Figure 5.7: Graph of Experimental Results VS Simulation Results ....... ....... ........... . 58
© Universiti Teknikal Malaysia Melaka
1
CHAPTER 1
INTRODUCTION
1.0
INTRODUCTION
Sheet metal was a common material used in the industry to produce several of
products. It was commonly undergo two groups of process which were cutting
process and plastic deformation process. In the report, the bending process of sheet
metal , 3 I 6L stainless steel was being concentrated. The die and punch used to bend
the sheet metal was designed and the bending process was simulated in order to
compare the results of simulation with existing experimental results.
1.1
SHEET MET AL FORMING
The sheet metal forming can be divided into two groups which are cutting
process and plastic deformation process. (Vukota Boljanovic, 2004)
Cutting process:
1.
•
Shearing
The process of cutting where the flat materials are cut from sheet, strip or
plate. It is classified by two types which is blade or cutter, whether rotary or
straight.
© Universiti Teknikal Malaysia Melaka
2
•
Blanking
The process of cutting the materials by using shear stresses between die and
punch in a closed contour.
•
Punching
The process of cutting where the various shaped holes are sheared in blanks
during the cutting operation.
•
Parting
The process of cutting the sheet metal into pieces or remove the pieces of
scrap of various shape from deep drawn pieces.
•
Lancing
The process where the work material is being cut with single line across the
work piece and no material is being removed. Hence, there is no scrap.
•
Shaving
The process of cutting operation to improve the accuracy and quality of
blanked part through the removing the thin strip of metal along its edges.
Plastic deformation process:
IL
•
Bending
The process of straining the flat metal sheet around its linear axis. Outer
surface of the bended metal sheet is stressed in tension while inner surface of
the bended metal sheet is compressed.
•
Twisting
The process of straining the flat sheet metal around the longitudinal axis.
•
Deep drawing
The process of forming the flat metal sheet into a box-shaped or cylindrical
part by using the punch into a die cavity.
© Universiti Teknikal Malaysia Melaka
3
•
Spinning
The process of forming work pieces from a tube or circular blank.
•
Stretch forming
The process of stretching a strips, metal sheet or profile over a shaped block
form to produced contoured parts.
•
Necking
The process where the top of the part are smaller than its body is being
shaped.
•
Bulging
The process that expanding the split female die by placing a conical,
curvilinear or tubular part in it.
•
Flanging
The process of hole-making on flat stock.
1.1.1
Bending
The force apply in the sheet metal bending is in the opposite directions
resulting the plastic deformation of metal. In sheet metal bending, the stress
characteristic are at the localised areas. The pressure or stress occors at the bend
radius while the remaining part or flat metal part is not undergo stress during the
bending. The outer surface of the sheet metal undergo tensile 'stress because the
surface being stretched or elongated. The inner surface of the sheet metal undergo
compressive stress because the surface being squeesed. Hence, the fracturing or
failure will occur on the outer surface and the wrinkling will occur on the inner
surface. (Lascoe, 1998)
© Universiti Teknikal Malaysia Melaka
4
T -Tension
Neutra l axis
C . Comp ression
Centerline of
bend radius
No stress in this
straight area
Figure l. l: Bending Stresses
(O.D. Lascoe, 1998)
1.1.2
Die and punch
P\mcn at.el
Figure 1.2: Sheet metal bending
(O.D. Lascoe, 1998)
Bending die and punch are generally classified according to their design. It is
whether they are simple or complex in design and their universality of application
whether they are universal of specific.
The design of bending die and punch depend on:
•
Complexity of the workpiece shape
•
Workpiece dimensions
•
Type of material of workpiece
•
The tolerances of workpiece
© Universiti Teknikal Malaysia Melaka
5
1.1.3
FEA Simulation
In FEA computer simulation, the effects of changing in any process
parameter can be observed prior to the actual tool manufacturing. Accurate
simulations and elaboration are performed during the process of tool design and
manufacturing phase. Different aspect of a FEA must be considered in order to
prepare an adequate numerical model. A numerical and experimental study need to
be carried out for better understanding on the various numerical and physical
parameters. The error can be encountered if any inappropriate criteria such as contact
description, material , method of unloading and element type are used during the
simulation. Therefore, the accuracy of information in FEA simulation is important
for the product designers and die makers. (Burchitz, 2008)
1.2
OBJECTIVE
•
To develop a design of die and punch for sheet metal bending by using
engineering parameter.
1.3
•
To simulate and analyse the bending of 3 l 6L stainless steel
•
To compare the results of simulation with existing experimental results.
SCOPE
•
Developments of design on die and punch by using SolidWorks and
simulate the results by using ANSYS .
•
Comparison between the results of simulation with experimental results
by applying force to the 3 l 6L stainless steel.
•
Characteristics of 3 l 6L stainless steel are observed during the simulation
analysis.
© Universiti Teknikal Malaysia Melaka
6
1.4
PROBLEM ST ATEMENT
Simulations and experiments are often used to engineering and science to test
and verify concepts. In bending process, the design of the die and punch are critical
in order to get the accurate results of sheet metal bending. The results of bending are
highly relied on the die and punch. Hence, the criteria in design the die and punch
must be strictly followed to decrease or minimise the defect occurred during bending
process. Besides, in simulation, the computer assumes the condition is ideal. For
example, the distribution of temperature is well distributed. Meanwhile, experiment
being performed in order to collect data that representative our real-life condition.
Hence, there will be difference between simulation results and experimental results.
© Universiti Teknikal Malaysia Melaka
1.5
FLOW CHART
Title selection
I
"I hereby declare that I have read this thesis and in my opinion this report is
sufficient in terms of scope and quality for the award of the degree of Bachelor of
Mechanical Engineering (Design & Innovation)"
Signature:
Supervisor:
Date:
.'X?... ｾ＠
.. ｾｊ＠
© Universiti Teknikal Malaysia Melaka
..
II
DESIGN AND SIMULATION
OF DIE AND PUNCH FOR SHEET METAL ON BENDING
NEOH THIAM HWA
This report is submitted in fulfillment of the requirements for the award
Bachelor of Mechanical Engineering (Design & Innovation)
Fakulti Kejuruteraan Mekanikal
Universiti Teknikal Malaysia Melaka
JUNE 2013
© Universiti Teknikal Malaysia Melaka
Ill
DECLARATION
"I hereby declare that the work in this report is my own except for summaries and
quotations which have been duly acknowledged. "
Signature:
ﾷ ﾷ ｾﾷ
ﾷ ﾷ ﾷ ﾷ ﾷ＠
Author:
NEOH THIAM HWA
Date:
Ｎｾ＠
...ｗＮｾ
ｎｾ＠
.. ｾＱＵ＠
© Universiti Teknikal Malaysia Melaka
IV
I dedicate this report to my loving mom, Madam Tan Cheok Tang, who also happens
to be my best friend . She is been my main supporter all these years. She instilled in
me a sense of curiosity about life and a thirst for knowledge. Besides, I would like to
take this opportunity to thank all of the people whose time, efforts and help were
given in order to help me complete this report on time. Furthermore, I want to thanks
all the staff in UTeM especially the lecturer and technicians in FKM to make my
PSM undergo smoothly and successfully. Thank you.
© Universiti Teknikal Malaysia Melaka
v
ACKNOWLEDGEMENT
First of all, I would like to thank sincerely to my supervisor, Dr Hady Efendy
for spending his precious time in guiding me with his expertise and giving his moral
support. The countless time that he spent in reflecting, encouraging, and advising
patiently throughout the entire process help me a lot in finishing this project. I have
learned many from him and gained my confidence from the project.
Secondly, I would also like to thank to En. Wan Farid for providing the
information and help for me regarding to the project. Without his help, I would not
able to complete my project successfully. Besides, special thanks to the staffs and
technicians in FKM for providing the assistance regarding with my request.
Last but not least, I would like to thank to all my friends for the
understanding and encouragement during my project.
Thank you.
© Universiti Teknikal Malaysia Melaka
VI
ABSTRAK
Proses lembaran logam lentur adalah satu proses dimana daya tekanan
dikenakan atas sekeping logam dalam usaha untuk mengubah struktur geometrinya.
Daya tekanan menyebabkan kepingan logam membengkok pada sudut yang
dikehendaki diantara penumbuk dan bekas. Waiau bagaimanapun, kecacatan
biasanya berlaku semasa proses lembaran menyebabkan kepingan logam calar,
kepesongan dan perubahan dalam ciri-ciri fizikal kepingan logam. Oleh itu, bekas
dan penumbuk kepingan logam direka dan dibangunkan dengan menggunakan
SolidWorks untuk meminimumkan kecacatan itu berlaku. Selepas itu, analisis unsur
terhingga (FEA) dengan perisian computer komersial, ANSYS digunakan untuk
memberi simulasi pembengkokan kepingan logam. Selepas itu, keputusan daripada
simulasi dibandingkan dengan keputusan eksperimen yang sedia ada. Ini kerana
terdapat perbezaan antara sirnulasi dengan eksperimen hasil daripada perbezaan
keadaan yang sebenar dengan keadaan yang ideal. Selain itu, kajian pembolehubah
prinsip lenturan lembaran logam juga dijalankan. Pembolehubah ini termasuk
perubahan mekanik seperti ketegangan, tekanan, dan penumpuan daya tekanan dalam
kepingan logam.
© Universiti Teknikal Malaysia Melaka
VII
ABSTRACT
Sheet metal bending processes is a process which force is applied on a piece
of sheet metal in order to modify its geometry structure. The force causing it to bend
at desired angle and shape between die and punch. However, defect during the
bending process cause by die and punch such as scratching, high percentage of
deflection and changes in the physical characteristic of the sheet metal usually occur.
Hence, the die and punch for sheet metal bending is being designed and developed
by using SolidWorks in order to minimize the defect occurs. Following by that, finite
element analysis (FEA) with commercial software, ANSYS, computer basedsimulation is being used to simulate the sheet metal bending. After that, the results
from the simulation are compared with the existing U-bending experiment results
due to the differences between real life conditions and ideal conditions. Besides, the
study of the principle variables of the sheet metal bending is being carried out. These
variables include mechanics of deformation such as stress, strain and force
concentration in the sheet metal.
© Universiti Teknikal Malaysia Melaka
VIII
TABLE OF CONTENTS
DECLARATION ..................................................................................................... III
DEDICATION .......................................................................................................... IV
ACKNOWLEDGEMENT ........................................................................................ V
ABSTRAK ................................................................................................................ VI
ABSTRACT ............................................................................................................ VII
CHAP'fER 1: INTRODUCTION ............................................................................. 1
I .O
INTRODUCTION .......... .. ..... ...... ...... ..................... ... ...... ........ .. ...... ... ........ ... I
I.I
SHEET METAL FORMING .. ... ........... ............... .. ... ... ... ... ...... ...... ....... .... .. .. I
I.I.I
Bending .. ... .. ........ .. ... ..... ... ...... ... ..... ...... .. .. ... .... ... ... .... .. .. ....... ... .. .. .... ... .... 3
I. I .2
Die and punch .......... .. .. ....... .... ... ......... .......... ........ ....... ............ .. .... .. ...... 4
I. I .3
FEA Simulation ..... ....... ... .... .. ..... .. .... .... ... .... ... ......... ... .. ... ..... ..... ..... .... .. .. 5
I .2
OBJECTIVE .. ..... ...... .... .... ........ ... ........ ..... ... .. .... ..... .... ....... ...... .... .. .... .... ...... .. 5
I .3
SCOPE ....... .. .. ..... ...... ..... .... .. ..... .... ... ... ...... ...... ... .... ..... .... .... .... ... ...... ..... ....... .. 5
I .4
PROBLEM STATEMENT ... ... ... .. .. .... ... ...... .... ....... ... .... .... .... ... .. .. ... .... ....... .. 6
I .5
FLOW CHART ... ..... ..... .... .......... ...... ..... ........ .. ..... .. ... .... .... .............. ...... ....... 7
CHAP'fER 2: LITERATURE REVIEW ................................................................. 8
2.0
INTRODUCTION TO BENDING PROCESS .. .............. .. ........... ... .... ......... 8
2. I
SHEET MET AL BENDING PARAMETERS ...... ....... ........ .... ... .... .. .. .... ..... 8
2.2
SPRINGBACK ... .. ....... .... .... .... .... ... ......... ...... ... ... .. .... .... ........ ... .... .... .. .... ... .. I l
2.3
THE CRYSTAL STRUCTURE OF METALS ..... ........ ........... ...... .. .. ........ . I2
2.4
THE PRACTICE OF U-SHAPE SPECIMEN ... ....... ............. ... ......... ......... 13
2.5
SIGNIFICANCE AND USE OF U-BEND SPECIMEN ... .... ....... ..... ...... ... I3
2.6
THE TEST SPECIMEN ................ .......... ... .... .... .... .. .. .... ....... ....... ..... ......... . 14
2.7
STRESS CONSIDERATIONS IN U-BEND SPECIMEN .. .. .. ...... .. ........... I6
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2.8
STRESSING THE U-BEND SPECIMEN .................... .... ...... .. ........... ...... . 16
2.9
EXPOSURE OF THE TEST SPECIMEN .... ....... ..................... .... ... ..... ...... 19
2.10
METHOD OF PRESSURE BENDING .... ........ .. .. ........ ...... .. .. .................... 19
2.11
FINITE ELEMENT ANALYSIS OF U-BEND ....... .... .............................. . 21
2.12
THE FEM SIMULATION RESULTS AND DISCUSSION ............. ....... .. 22
CHAP'fER 3: METHODOLOGY .......................................................................... 24
3.0
INTRODUCTION .. ........ ..... .................... .... ....... ...... ... ....... ............. .. ...... .. .. 24
3.1
INFORMATION GATHERING .......... ..... .. ...... ................ .... ...... .. .... .... .. .... 25
3.2
PROBLEM IDENTIFICATION .... ........ .... .... ................ ...... .. ...... .... .... .. ..... 25
3.3
PRODUCT DESIGN SPECIFICATION ............................ .... .......... ... ..... .. 26
3.3.1
Product Identification ............ .. .... ............ ................... .. .............. .. ........ 26
3.3.2
Key Project Deadlines ......... ... ...... .. ..... ... ...... .... .... ... .. ...... ..... ... .... .... .... . 26
3.3.3
Physical Description ... .................... ....... ........ ... ........... ... ......... ... .......... 26
3.4
CONCEPT GENERATION ..... ..... .......................... .. ...... ................ .. .... ...... 27
3.4.1
House of Quality ........... ........ .... ..... .. ............... .. ....... .. ..... ...... ...... ..... ... .. ... 27
3.4.2
Morphological Chart .. ............. ................................. .............................. .. 30
3.5
CONCEPT SELECTION ......... .. .................................. ...... ............ .... .. ....... 32
3.5 .1
Objective Tree ..... ....... ..... ...... .... ............ .. ........ ... ....... .. ... .... ..... .... ............. 33
3.5.2
Weighted Decision Matrix ...... .... .. ....... ..... .... ... ....... ................. .. .... .... ...... 35
3.6
CONCEPTUAL DESIGN .... .. ..... .. .... .... ........................... .. ...... .... ....... ..... ... 37
3.7
SIMULATION ........ ........ ... ........ .... ... ..... .... .... ................... ... ..... .... ... .... ...... . 38
3.8
GANTT CHART ..... ........ ... .... ... .... .... ...... .. .... ........ ..... ...... .... .... .... .... .... .. ..... 42
CHAP'fER 4: DESIGN ........................................................................................... 44
4.0
DETAIL ORAWING .. ............................. .... ...... ............ .. ,, ............... ..... ..... 44
CHAP'fERS: RESULT ANDDISCUSSION ........................................................ 51
5.0
DIE AND PUNCH SIMULATION RESULTS ............ ...... .... ...... .. .... ........ 51
5.1
BENDING PROCESS IN THE EXPERIMENT .... ...... ........ .. .. ...... .... ........ 53
5.2
SHEET METAL SIMULATION RESULTS ...... .... ............ .. ...... .... ..... .. ..... 55
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CHAPTER 6: CONCLUSION ................................................................................ 60
REFERENCES ..... .... ........ ...... ... ......... ........... .... ..... ................. .......... ......... ..... .... ....... 61
APPENDIX A: ASSEMBLY VIEW ....... ..... ... .. ... .. ..... ... ............. .......... ....... ... ....... ... 61
APPENDIX B: PUNCH ... ..... .. .............. ........ ............. .... .................. .... ......... ... ..... ..... 64
APPENDIX C: DIE ............ .... .... ..... .. .... ....... ... ..... ........... ......... ... ....... .......... ........ ... .. 65
A PPENDIX D: SLIDING GUIDE ................. ...... ....... ........ .. .. ...... .............. .. ..... ..... ... 66
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LIST OF TABLES
Table 2.1: Bending Characteristic ... ....... .. ... .... ... .. ......... .. .... ... ........... ... ...... ...... ... ........ . 9
Table 2.2: Bending parameters (Source: CustomPartNet, 2009) ............ ...... ... ....... ... l 0
Table 2.3: Typical U-Bend specimen dimensions ... ... .... ......... .... .... ..... ...... ..... ....... ... l 5
Table 3.1: House of Quality (HOQ) .... ... .... .. .. ....... ... ...... .......... ........ ......... .. ........... .. .. 29
Table 3.2: Morphological Chart ........... .. ....... ....... ............... ........... ........ .. ... ....... ... ..... 31
Table 3.3: Evaluation scheme for design alternatives or objectives ........ .... ... ... .. .... .. 35
Table 3.4: Weighted Decision Matrix .. ....... .. .... ........ ..... ...... ........ .. ..... .... .. ....... ........ .. 36
Table 3.5: Gantt chart of PSM l .. ...................... .. ....... ...... ... .... ............. .. ....... ........ .... 42
Table 3.6: Gantt chart of PSM 2 ...... .... ...... .. ...... .... ............. ............ .......... ................. 43
Table 5.1: Comparison between existing results of experiment and the simulation
results .................................... ...... ... .. ... ....... .. ........ .... ...... ............... ................. ........ .. .. 57
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LIST OF FIGURES
Figure l . l: Bending Stresses ............... ... .. ...... ... ... ........ .... .. .... ....... ... .. ....... .... ....... .... .... 4
Figure 1.2: Sheet metal bending .... .. .... .... ... .... ... ..... ...... ......... ... .... ....... .. .... .... ..... ....... ... 4
Figure 2. l: Bending diagram ...... ........ ......... ... .... .. ......... .... ...... .... .... .. ... ... ........ ...... ... .... 8
Figure 2.2: Neutral axis ... .. ... ....... .... ..... ... ... ... ....... ... ....... ......... .... .... ..... .... .... .... ..... ..... 10
Figure 2.3: Springback .... .. ... ... .... ...... ...... ... ..... ... ......... .. ... ...... .. .. .. .......... .... .. .... .... .... .. 11
Figure 2.4: Crystal structure of metals: (a) the body-centered cubic; (b) the facecentered cubic; (c) the hexagonal close-packed ... ........ ............. ... ... ....... ..... ... ....... .... . 12
Figure 2.5: Typical Stressed U-bends ...... .... ........ ...... .. ....... .. ..... ............ ...... .. .. .. ... ..... 13
Figure 2.6: Method of stressing U-Bend specimen - One stage stressing ......... .. .... .. 17
Figure 2. 7: Method of stressing U-Bend - Two stage method ... .... .... ......... .. .... ....... .. 18
Figure 2.8: True sress-true strain relationships for stressed U-Bends ... ... ... ......... ..... 18
Figure 2.9: Bending action- pressure bending ... ........ ... .... .. .......... ... ... ...... .. .......... ..... 19
Figure 2. l 0: Two methods of pressure bending. (a) Air bending; (b) Pressure bending
... ... ........... ... ........ ...... ... ... ................................... ................ .... .... .......... ..... ... .............. . 20
Figure 2.11: Precision U-bending models. (a) Without the coined bead. (b) With the
coined bead .... ........ ......... ... ...... ........... .... .... .. ....... .. ......... ... .... ........ .......... .. .... ....... .. .... 21
Figure 2.12: Stress distribution analysis in the workpiece and the spring-back/springgo featrue. (a) 90° (b)60° ....... .... .... ...... ... ...... .... ...... ........... ...... .... .. ... .. ..... ... .... ... .... ..... 23
Figure 3.1: Flow chart of Methodology ... ... ..... ....... .. .... .... ... ............. ...... ... ..... ......... .. 24
Figure 3.2: Objective tree for the die and punch ..... ......... ..... ........ ... .................. ........ 34
Figure 3.3: Conceptual design of die and punch ... ..... ..... .. .. .......... ... ｾ＠ ....... ...... ......... ... 37
Figure 3.4: Fixed geometry of die .... .... ... .... .... .... .... .... ........ ... .. ....... ... .... ...... ... .... ....... 39
Figure 3.5: Force applied on the die ........ .... ...... ..... ... ... ... .. ... ........... .. ...... ... ..... ........ ... 39
Figure 3.6: Fixed geometry of punch ..... ........ ... ... .... ....... .. ... ........ .... ... .. ...... ......... ... ... 39
Figure 3.7: Force applied on the punch ... ... ....... ... ... .... .... .. ........ ... ........ ......... .... .. ....... 39
Figure 3.8: The dimension of the Stainless Steel 316L sheet metal ..... ... .... ... ..... .... .. 40
Figure 3.9: The Displacement (punch) and Fixed Support (die) with the sheet metal
on the middle .... ..... ...... ... ...... ... ..... ........... ... .... ...... ..... .. ...... ..... ..... .... ............... ..... ...... . 41
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Figure 3.10: Mesh generated on the die, punch and sheet metal ... ........ ... ...... ...... .... . 41
Figure 4.1: Exploded view of die and punch ..... .... ............. ... .. ..... ........... ......... ......... 44
Figure 4.2: Third angle projection (assembly) of die and punch ..... ..... ... ............ ...... 45
Figure 4.3: Third angle projection of die ...... .. ..... .. ...... ........ ......... .... .... ... .... ... ........... 46
Figure 4.4: Third angle projection of punch ...... .. ......... .... ........ ...... .. .... ... .... .... .. ....... . 47
Figure 4.5: Third angle projection of sliding guide ....... ... ... .. .... ...... ....... .... ..... ........ .. 48
Figure 4.6: Third angle projection of washer M8 ..... ... .... ...... ...... ............ ..... ......... .... 49
Figure 4.7: Third angle projection of hex cap screw M8 .. ...... ...... .. .. .. .... ... ........ ... ... .. 50
Figure 5.1 : Static displacement of die .. ........... ................. ..... .. ................ .......... ......... 51
Figure 5.2: Static displacement of punch ...... .. .. .... .... ........ .. ..... .......... ....... ... ........ ... ... 52
Figure 5.3: Die and punch installed in the Universal Testing Machine ....... ..... .. .. ..... 53
Figure 5.4: Bending process of sheet metal .. ......... .. ..... ..... ..... .. .. ...... ........ ..... ... ... .... .. 54
Figure 5.5: Simulation result of sheet metal bending with thickness 0.6mm ...... .. .... 55
Figure 5.6: Stress distribution on the U-bend sheet metal .... ....... ..... ....... .. .......... ...... 56
Figure 5.7: Graph of Experimental Results VS Simulation Results ....... ....... ........... . 58
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CHAPTER 1
INTRODUCTION
1.0
INTRODUCTION
Sheet metal was a common material used in the industry to produce several of
products. It was commonly undergo two groups of process which were cutting
process and plastic deformation process. In the report, the bending process of sheet
metal , 3 I 6L stainless steel was being concentrated. The die and punch used to bend
the sheet metal was designed and the bending process was simulated in order to
compare the results of simulation with existing experimental results.
1.1
SHEET MET AL FORMING
The sheet metal forming can be divided into two groups which are cutting
process and plastic deformation process. (Vukota Boljanovic, 2004)
Cutting process:
1.
•
Shearing
The process of cutting where the flat materials are cut from sheet, strip or
plate. It is classified by two types which is blade or cutter, whether rotary or
straight.
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•
Blanking
The process of cutting the materials by using shear stresses between die and
punch in a closed contour.
•
Punching
The process of cutting where the various shaped holes are sheared in blanks
during the cutting operation.
•
Parting
The process of cutting the sheet metal into pieces or remove the pieces of
scrap of various shape from deep drawn pieces.
•
Lancing
The process where the work material is being cut with single line across the
work piece and no material is being removed. Hence, there is no scrap.
•
Shaving
The process of cutting operation to improve the accuracy and quality of
blanked part through the removing the thin strip of metal along its edges.
Plastic deformation process:
IL
•
Bending
The process of straining the flat metal sheet around its linear axis. Outer
surface of the bended metal sheet is stressed in tension while inner surface of
the bended metal sheet is compressed.
•
Twisting
The process of straining the flat sheet metal around the longitudinal axis.
•
Deep drawing
The process of forming the flat metal sheet into a box-shaped or cylindrical
part by using the punch into a die cavity.
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•
Spinning
The process of forming work pieces from a tube or circular blank.
•
Stretch forming
The process of stretching a strips, metal sheet or profile over a shaped block
form to produced contoured parts.
•
Necking
The process where the top of the part are smaller than its body is being
shaped.
•
Bulging
The process that expanding the split female die by placing a conical,
curvilinear or tubular part in it.
•
Flanging
The process of hole-making on flat stock.
1.1.1
Bending
The force apply in the sheet metal bending is in the opposite directions
resulting the plastic deformation of metal. In sheet metal bending, the stress
characteristic are at the localised areas. The pressure or stress occors at the bend
radius while the remaining part or flat metal part is not undergo stress during the
bending. The outer surface of the sheet metal undergo tensile 'stress because the
surface being stretched or elongated. The inner surface of the sheet metal undergo
compressive stress because the surface being squeesed. Hence, the fracturing or
failure will occur on the outer surface and the wrinkling will occur on the inner
surface. (Lascoe, 1998)
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T -Tension
Neutra l axis
C . Comp ression
Centerline of
bend radius
No stress in this
straight area
Figure l. l: Bending Stresses
(O.D. Lascoe, 1998)
1.1.2
Die and punch
P\mcn at.el
Figure 1.2: Sheet metal bending
(O.D. Lascoe, 1998)
Bending die and punch are generally classified according to their design. It is
whether they are simple or complex in design and their universality of application
whether they are universal of specific.
The design of bending die and punch depend on:
•
Complexity of the workpiece shape
•
Workpiece dimensions
•
Type of material of workpiece
•
The tolerances of workpiece
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1.1.3
FEA Simulation
In FEA computer simulation, the effects of changing in any process
parameter can be observed prior to the actual tool manufacturing. Accurate
simulations and elaboration are performed during the process of tool design and
manufacturing phase. Different aspect of a FEA must be considered in order to
prepare an adequate numerical model. A numerical and experimental study need to
be carried out for better understanding on the various numerical and physical
parameters. The error can be encountered if any inappropriate criteria such as contact
description, material , method of unloading and element type are used during the
simulation. Therefore, the accuracy of information in FEA simulation is important
for the product designers and die makers. (Burchitz, 2008)
1.2
OBJECTIVE
•
To develop a design of die and punch for sheet metal bending by using
engineering parameter.
1.3
•
To simulate and analyse the bending of 3 l 6L stainless steel
•
To compare the results of simulation with existing experimental results.
SCOPE
•
Developments of design on die and punch by using SolidWorks and
simulate the results by using ANSYS .
•
Comparison between the results of simulation with experimental results
by applying force to the 3 l 6L stainless steel.
•
Characteristics of 3 l 6L stainless steel are observed during the simulation
analysis.
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1.4
PROBLEM ST ATEMENT
Simulations and experiments are often used to engineering and science to test
and verify concepts. In bending process, the design of the die and punch are critical
in order to get the accurate results of sheet metal bending. The results of bending are
highly relied on the die and punch. Hence, the criteria in design the die and punch
must be strictly followed to decrease or minimise the defect occurred during bending
process. Besides, in simulation, the computer assumes the condition is ideal. For
example, the distribution of temperature is well distributed. Meanwhile, experiment
being performed in order to collect data that representative our real-life condition.
Hence, there will be difference between simulation results and experimental results.
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1.5
FLOW CHART
Title selection
I