http://www.iaeme.com/IJMET/index.asp 249 [email protected]
International Journal of Mechanical Engineering and Technology (IJMET)
Volume 7, Issue 3, May–June 2016, pp.249–266, Article ID: IJMET_07_03_023
Available online at
http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=7&IType=3
Journal Impact Factor (2016): 9.2286 (Calculated by GISI) www.jifactor.com
ISSN Print: 0976-6340 and ISSN Online: 0976-6359
© IAEME Publication
COMPARATIVE STUDY OF THE EFFECT
OF DWELLING THE PUNCH AT THE BDC
VS WITHOUT DWELLING AT THE BDC ON
THE DEEP DRAWING PROCESS BY FE
SIMULATION
Priya B. Vhangade
M.E. Cad/Cam & Robotics Student,
Fr. Conceicao Rodrigues College of Engineering,
Bandra, Mumbai, India
D.S.S. Sudhakar
H.O.D, Department of Mechanical Engineering, Fr. Conceicao Rodrigues College of Engineering,
Bandra, Mumbai, India
Rajeev A. Solanki
Manager, Department of New Product Engineering,
M/S Larsen & Toubro, Powai, Mumbai, India
Basappa U. Vhangade
H.O.D, Department of physics,
Mahatma Phule Arts, Science & Commerce College,
Panvel, Mumbai, India
ABSTRACT
Since past many years the manufacturing industry has made use of the
conventional presses for sheet metal forming. Many advantages as well as the
limitations of the conventional presses are known by now. The servo presses
came into existence many years ago but are now starting to gain popularity
because of its flexible slide motion programming and other significant
characteristics which are unique to the servo presses. Majority of the
components in various industries are made by deep drawing sheet metal
process. So these growing demands need new sheet metal forming techniques
which improve the quality, increase production and save time. To be able to
dwell at the BDC for some time is a unique characteristic of the servo press
compared to the conventional press.
Priya B. Vhangade, D.S.S. Sudhakar, Rajeev A. Solanki and Basappa U. Vhangade
http://www.iaeme.com/IJMET/index.asp 250 [email protected]
This paper presents an investigation of the effect of the punch dwelling at
the BDC in a servo press vs. without dwelling at the BDC in a conventional
press to find their influence on the deformation behavior of the sheet metal by
finding the variation in formability, contact forces, displacement, % thinning,
stress distribution and von misses stress of a deep drawn cup using finite
element simulations. The finite element simulation analysis is carried out by
using Altair Hyperform and Radioss solver.
Key words: Deep Drawing, HYPERFORM, Simulation, Dwell, Servo Press,
RADIOSS, Bottom Dead Centre (BDC)
Cite this Article Priya B. Vhangade, D.S.S. Sudhakar, Rajeev A. Solanki and
Basappa U. Vhangade, Comparative Study of The Effect of Dwelling The
Punch at The BDC Vs without Dwelling at The BDC on The Deep Drawing
Process by Fe Simulation. International Journal of Mechanical Engineering
and Technology, 7(3), 2016, pp. 249–266.
http://www.iaeme.com/currentissue.asp?JType=IJMET&VType=7&IType=3
1. INTRODUCTION
The sheet metal forming technology is utilized by majority of the automotive,
manufacturing and appliances producing industries. With the increasing popularity of
the finite element simulations, they are performed repeatedly in the design feasibility
studies of die design and production tooling [1]. Deep drawing is one of the most
important forming processes in any industry. Deep drawing is a process for shaping
flat sheets into cup like cylindrical component by radially drawing metal blank into
the die cavity with the help of a punch without fracture or excessive localized
thinning. The control and design of a deep drawing process depends not only on the
equipment used, geometry, workpiece material, but also on the condition at the tool
workpiece interface and the mechanics of plastic deformation [1]. Hence the
upcoming servo press technology makes use of various other additions in the sheet
metal forming process due to its programmable slide motions as compared to that of
the conventional press. The servo press eliminates the need of flywheel, clutch and
brake and replaces it with high power servo motor as shown in figure 1 [2].
Figure 1 Mechanical press vs. servo press [2]
Hence, it is possible to obtain flexible slide motions in a servo press due to the use
of servo motors. The capacity to dwell at the BDC is one of the most important
functions of a servo press because it helps in easy forming of advanced high strength
steels and other high strength materials. Also it helps in reducing the number of
forming steps otherwise required and hence increases productivity in lesser time. In
the figure 2 we can see the comparison between press cycles of a mechanical press vs.
servo press.
Comparative Study of The Effect of Dwelling The Punch at The BDC Vs without Dwelling at
The BDC on The Deep Drawing Process by Fe Simulation
http://www.iaeme.com/IJMET/index.asp 251 [email protected]
Figure 2 Slide motion flexibility in servo drive presses [3, 4, 2].
Hence it is important to analyse the effect of dwell on the sheet metal forming
process. The finite element analysis software is regularly used in the design
assessment of dies and stamping tooling in the manufacturing industry.
In the current work case is studied for a deep drawing process of a cup in which
the cup is first drawn without providing dwell at the BDC and then by providing
dwell at the BDC. The finite element simulation of these two processes are carried out
and the variation or effect on formability, contact forces, displacement(mag),
%thinning, stress and von mises stress(scalar value) are studied by the FE simulations.
2. LITERATURE REVIEW
Kozo Osakada, D., (2009) [5] conducted a study on mechanical servo press
technology for metal forming. Here he has explained about the various aspects of
servo presses which include the different slide motions, their applications, various
designs of the servo presses, arrangement etc. Servo drive presses have capabilities to
improve process conditions and productivity in metal forming.
T. Altan, A. Groseclose, (2009) [3] studied and reviewed the servo drive presses
and their capability to improve productivity and to improve process conditions in
metal forming. He has also elaborated about the applications of these presses in
various sheet metal forming processes such as deep drawing, blanking, warm forming
etc. the literature also describes about various press designs and major applications.
Long Ju [6] performed the investigation of forming speed and friction on
drawability of Al 5182-O using a servo press with CNC cushion. Lubrication and
forming speed effect the productivity and part quality. Servo presses have the
capability to provide variable ram motions for various stamping operations. In the
present study, deep drawing tests were conducted in a servo press to investigate the
effects of forming speed on the drawability for Al alloy (5182-O) sheets at room
temperature. The results and discussions gave insights into the effects of forming
speed on deep drawing process of aluminum alloys at room temperature.
Priya B. Vhangade, D.S.S. Sudhakar, Rajeev A. Solanki and Basappa U. Vhangade
http://www.iaeme.com/IJMET/index.asp 252 [email protected]
Ryo Matsumoto, (2013) [7] studied about Shape accuracy in the forming of deep
holes with retreat and advance pulse ram motion on a servo press. Since the ram speed
and motion of servo presses can be programmed with a servomotor through CNC
control, servo presses have led to new forming processes. Here the shape accuracy of
the formed hole is discussed with experimental and finite element simulation results
in terms of lubrication state and temperature change.
From above findings and discussions, it is clear that researchers have been
working on the various programmable slide motions of the servo press and on their
benefits in the forming process. It is also evident that for this purpose the researchers
are using FE approach to know about the effects of their study. The FE approach also
helps in reducing cost which would otherwise be caused by time consuming
experimental trial and error method.
3. RESEARCH GAP
After the analysis of the literature, it was found that the servo presses are gaining
importance quickly due to its various benefits and customizable abilities as compared
to the conventional presses. Researchers have conducted various experiments and
tests on the servo press which shows various benefits in forming operations due to its
programmable slide motions. Hence, the servo press not only consists of the speed of
a mechanical press but can also provide tonnage as by a hydraulic press. Many
researchers have investigated regarding the effect of forming speed for different sheet
metal forming processes, analysis of friction with advance pulse ram motion in a
servo press, shape accuracy of deep holes on servo press and other such related topics
but very few researchers have carried out the differences caused in the sheet metal by
dwelling at the BDC vs. without providing dwell at the BDC with the help of FE
simulations. There lies an immense future scope in studying different motions of the
servo press and what effects they carry. Hence, the aim of the present work is to
investigate the effect of dwelling at the BDC vs. without dwelling at the BDC on the
variation in stress distribution, displacement, contact forces, von misses stress and
formability of a deep drawn cup using finite element simulations.
4. RESEARCH METHODOLOGY
The research methodology used for the current work is as shown in the figure 1
below.
Comparative Study of The Effect of Dwelling The Punch at The BDC Vs without Dwelling at
The BDC on The Deep Drawing Process by Fe Simulation
http://www.iaeme.com/IJMET/index.asp 253 [email protected]
Figure 3 Methodology of deep drawing simulation
The die and blank geometry is prepared by using the modeling software PRO-E
and then is imported into the preprocessor Hyperform. The preprocessing steps are
carried out in which boundary conditions such as die and blank meshing, clearance,
material properties etc. is applied to generate the required tooling setup for carrying
out the deep drawing simulation analysis. The material used is CRDQ steel which is
elastic plastic material of thickness 1.2mm. The material properties are shown in the
given table 1.
Priya B. Vhangade, D.S.S. Sudhakar, Rajeev A. Solanki and Basappa U. Vhangade
http://www.iaeme.com/IJMET/index.asp 254 [email protected]
Table 1 Properties of CRDQ steel
Sr. No. Properties Values
1 Young’s modulus (E) 210 Gpa
2 Poisson’s ratio (ν) 0.3
3 Frictions coefficient (µ) 0.1
4 Density (ρ) 7800 kg/m3
5 Yield Stress (σy) 250 Mpa
6 Ultimate tensile Stress (σt) 550 Mpa
7 Tangent modulus (Et) 0.5 Gpa
8 Strain hardening exponent (n) 0.22
4. FINITE ELEMENT MODEL
Drawing of a circular cup is shown in fig 2 [8]. All the important dimensions of the
punch, die and blank holder are shown in figure 3 [9] and are mentioned in table 2.
Figure 4 Cylindrical cup
Comparative Study of The Effect of Dwelling The Punch at The BDC Vs without Dwelling at
The BDC on The Deep Drawing Process by Fe Simulation
http://www.iaeme.com/IJMET/index.asp 255 [email protected]
Figure 5 Geometry of Drawing Dies Assembly [9]
Table 2 Geometric Parameters
Blank thickness (t) 1.2 mm
Blank size radius (BR) 17 mm
Punch radius (PR) 9.64 mm
Die radius (DR) 10 mm
Punch nose radius (rp) 6 mm
Die shoulder radius (rd) 2 mm
Radial clearance (wc) 0.33 mm
Cup Height of the draw (h) 15 mm
Figure 6a, 6b shows simulation setup of a deep drawing process generated at the
end of preprocessing in hyperform software.
Priya B. Vhangade, D.S.S. Sudhakar, Rajeev A. Solanki and Basappa U. Vhangade
http://www.iaeme.com/IJMET/index.asp 256 [email protected]
Figure 6(a) Setup Consisting Of Die, Binder, Blank and Punch
. Figure 6(b) Front View of Setup
6. RESULTS AND DISCUSSION
Here we are going to study the effects of providing dwell for few seconds at the BDC
which is possible by a servo press. We are comparing the results for slide motion
without dwell vs. the slide motion with dwell at the BDC for 4 sec. The blank holder
force provided is 28000 N. We conduct the simulation preprocessing in Hyper form
and Post processing in Radioss. And then view the results in Hyperview. Hence, we
check their effects on following variables:
FLD (Formability)
Contact forces (Mag)
Displacement (mag)
% thinning
Stress (von mises)
Comparative Study of The Effect of Dwelling The Punch at The BDC Vs without Dwelling at
The BDC on The Deep Drawing Process by Fe Simulation
http://www.iaeme.com/IJMET/index.asp 257 [email protected]
Major stress (P1)
Minor stress (P3)
Von mises stress
6.1. FLD (forming limit diagram)
Figure 7(a) FLD without dwell at BDC
Figure 7(b) Fld plot with dwell at the BDC.
In the fld plot without dwell at the BDC we can see that the plot shows near
marginal failure approaching at some points and also the safe zone formation is bit
distorted compared to the safe zone formation in the plot with dwell at the BDC.
Whereas the fld plot with dwell displays almost no marginal failure inspite having all
the same input parameters.
Priya B. Vhangade, D.S.S. Sudhakar, Rajeev A. Solanki and Basappa U. Vhangade
http://www.iaeme.com/IJMET/index.asp 258 [email protected]
6.2. Contact forces (mag)
Figure 8(a) contact forces without dwell
Figure 8(b) contact forces with dwell.
Comparative Study of The Effect of Dwelling The Punch at The BDC Vs without Dwelling at
The BDC on The Deep Drawing Process by Fe Simulation
http://www.iaeme.com/IJMET/index.asp 259 [email protected]
From the contour plot analysis system results we can see that the maximum
contact force is 2.857E+02 KN in the plot without dwell as compared to the
maximum contact force in the plot with dwell which is 1.952E+02 KN. Hence the
contact force in plot without dwell is more than in plot with dwell.
6.3. Displacement (mag)
Figure 9(a) Displacement without dwell
Figure 9(b) Displacement with dwell
The displacement plot without dwell shows little compressed zone as compared to
that in the plot with dwell. Hence, we can say that the displacement plot of forming
with dwell is safer and has tendency for lesser wrinkle or compression.
Priya B. Vhangade, D.S.S. Sudhakar, Rajeev A. Solanki and Basappa U. Vhangade
http://www.iaeme.com/IJMET/index.asp 260 [email protected]
6.4. %Thinning
Figure 10(a) % Thinning without dwell
Figure 10(b) % Thinning with dwell.
The maximum % thinning area is more in the plot with dwell as compared to the
plot without dwell. The value of maximum % thinning during forming with dwell is
around 19% while that in without dwell is around 21%. So this shows that the forming
with dwell process can be extremely useful for high strength alloy forming as they
need more tonnage compared to steel.
Comparative Study of The Effect of Dwelling The Punch at The BDC Vs without Dwelling at
The BDC on The Deep Drawing Process by Fe Simulation
http://www.iaeme.com/IJMET/index.asp 261 [email protected]
6.5. Stress (von mises)
Figure 11(a) Stresses without dwell
Figure 11(b) Stresses with dwell
From both the plots above, maximum stress is more in the plot without dwell than
in the plot with dwell. The value of maximum stress in plot without dwell is 637 Mpa
and that of with dwell is 436 Mpa. In the plot with dwell there are very few maximum
stresses induced during forming as compared to the plot without dwell.
Priya B. Vhangade, D.S.S. Sudhakar, Rajeev A. Solanki and Basappa U. Vhangade
http://www.iaeme.com/IJMET/index.asp 262 [email protected]
6.5.1. Major stress (P1)
Figure 12(a) Major stresses without dwell
Figure 12(b) Major stresses with dwell.
In the plots above, the maximum value of major stress induced in plot without
dwell is 727 Mpa and in the plot with dwell is 500 Mpa.
Comparative Study of The Effect of Dwelling The Punch at The BDC Vs without Dwelling at
The BDC on The Deep Drawing Process by Fe Simulation
http://www.iaeme.com/IJMET/index.asp 263 [email protected]
6.5.2. Minor stress (P3)
Figure 13(a) Minor stresses without dwell
Figure 13(b) Minor stresses with dwell
From the plots above, The maximum value of minor stress in plot without dwell is
510 Mpa and that in plot with dwell is 335 Mpa.
Priya B. Vhangade, D.S.S. Sudhakar, Rajeev A. Solanki and Basappa U. Vhangade
http://www.iaeme.com/IJMET/index.asp 264 [email protected]
6.6. Von mises (scalar value)
Figure 14(a) Von mises stress without dwell
Figure 14(b) Von mises stress with dwell.
Comparative Study of The Effect of Dwelling The Punch at The BDC Vs without Dwelling at
The BDC on The Deep Drawing Process by Fe Simulation
http://www.iaeme.com/IJMET/index.asp 265 [email protected]
From the plots above, the maximum value of von mises stress in the plot without
dwell is 480 Mpa and in the plot with dwell is 325 Mpa. So, we can see that the von
mises stresses developed in the plot with dwell is more safer compared to that in
without dwell.
7. ADVANTAGES OF DWELLING OVER NORMAL SLIDE
MOTION
Dwelling allows the metal flow to arrange itself before the next impact, hence
resulting in better forming as we can see in the FLD.
Dwelling helps in distribute the stresses more evenly.
Dwelling can be the best option for high strength steels and alloy forming.
One most important application is also that the dwell time can be utilized to perform
in-die operations or other secondary operations, which hence helps in saving lot of
time as well as money which would otherwise be spent in putting a whole new set up.
Hence, dwelling helps in increasing the productivity and reducing the production
time.
8. CONCLUSION
Summary of the comparative analysis between the results without and with dwell are
found. Several conclusions can be obtained from the results of the study.
The finite element simulation provides a satisfactory determination in the differences
obtained by with dwell and without dwell.
The results from this work open the platforms for further determining the benefits of
dwell on different HSS and other alloy metal forming.
The simulation results reveal that, due to providing dwell there is more uniform
distribution of stresses, direct impact on the sheet metal is less, also there are some
reduction in wrinkling and the material gets time to flow during the dwell period
which results in more safer forming.
REFERENCES
[1] Anup S. Atal , M. T. Shete, Formability Analysis of Deep drawing Process by
Finite Element Simulation, International Journal of Science and Research, 3(6),
June 2014.
[2] Priya Vhangade, D.S.S. Sudhakar, Rajeev Solanki, Study of servo drive press
technology – A Review, 5(4), April 2016.
[3] Altan, T., Groseclose, A., 2009, Servo-Drive Presses – Recent Developments.
[4] Miyoshi, K., Current Trends in Free Motion Presses, Proceedings of the 3rd
Japan Society for Technology of Plasticity (JSTP), Int. Seminar on Precision
Forming, March 2004.
[5] K. Osakada (1)a*, K. Mori (2)b, T. Altan (1)c, P. Groche (1)d , Mechanical servo
press technology for metal forming, Annals 2011(60) 2.
[6] Long Ju, Tingting Mao, Shrinivas Patil, Taylan Altan, Investigation of forming
speed and friction on drawability of Al 5182-O using a servo press with CNC
cushion.
[7] Ryo Matsumoto, Jae-Yeol Jeon, Hiroshi Utsunomiya, Shape accuracy in the
forming of deep holes with retreat and advance pulse ram motion on a servo
press, Journal of Materials Processing Technology 213 (2013) 770–778.
Priya B. Vhangade, D.S.S. Sudhakar, Rajeev A. Solanki and Basappa U. Vhangade
http://www.iaeme.com/IJMET/index.asp 266 [email protected]
[8] Sachin s. chaudhari, Navneet K. Patil, Springback Prediction of Sheet Metal In
Deep Drawing Process, IJMET, 6(12), Dec 2015, pp. 9–17.
[9] Mohd Naeemil Mahmudi Bin Mahmud, Reducing Wrinkling and Tearing of
Deep Draw Part, M. Tech thesis, Universiti Malaysia Pahang, May 2012, pp. 16.
[10] Dr.R.Uday Kumar, Dr.P.Ravinder Reddy, Influence of Viscosity on Fluid
Pressure in Hydroforming Deep Drawing Process. International Journal of
Mechanical Engineering and Technology, 3(2), 2012, pp. 604–609.
[11] Dr.R.Uday Kumar, Mathematical Modeling and Evaluation of Radial Stresses In
Hydroforming Deep Drawing Process. International Journal of Mechanical
Engineering and Technology, 3(2), 2012, pp. 693–701.
.