34th INTERNATIONAL CONFERENCE ON
PRODUCTION ENGINEERING
28. - 30. September 2011, Niš, Serbia
University of Niš, Faculty of Mechanical Engineering
NUMERICAL SIMULATION OF UPSETTING OF PRISMATIC BILLETS BY V-SHAPE
DIES WITH EXPERIMENTAL VERIFICATION
Dragisa VILOTIC1, Miroslav PLANCAK1, Sergej ALEXANDROV2, Aljosa IVANISEVIC1, Dejan MOVRIN1,
Mladomir MILUTINOVIC1,
1
Faculty of Technical Science, University of Novi Sad, Trg Dositeja Obradovica 6, Novi Sad, Serbia
vilotic@uns.ac.rs, plancak@uns.ac.rs, aljosa@uns.ac.rs, movrin@uns.ac.rs, mladomil@uns.ac.rs
2
Institute for Problems in Mechanics, Russian Academy of Science, 101-1 Prospect Vernadskogo, 119526
Moscow, Russia
sergei_alexandrov@yahoo.com
Abstract: Upsetting processes represent an elementary operation which is often integrated into complex
technological processes of cold and hot bulk metal forming. These processes also have significant role in
material formability analyses.
In this paper, results obtained by numerical simulation of upsetting of prismatic specimens by V-shape
dies in cold condition are presented. Numerical simulation is performed using Simufact Forming
program package.
Results obtained by numerical simulation of upsetting of prismatic billets with square section of material
C45E steel by V-shape dies with die angle of 120° are verified experimentally.
Key words: Upsetting, Numerical simulation, V-shape dies, Prismatic billets
1. INTRODUCTION
Upsetting processes have an important role in the
technology of bulk metal forming. For the upsetting of
prismatic or cylindrical billets, flat dies are most often
used, although upsetting can be obtained whit tools of
different geometry.
Given in [1] is the stress analysis in deformation zone in
upsetting of workhardening material by cylindrical dies.
The load and average pressure as a function of die stroke
were determined and compared to results obtained
experimentally.
In paper [2] stress analysis of upsetting prismatic billet
with concave-curve dies is obtained. Solution of contact
stress and forming load, i.e. distribution of contact stress
and forming load in upsetting cylinder by conical dies is
presented in [3].
a)
b)
c)
Fig.1. Upsetting with dies of various geometry:
a) cylindrical dies [1]
b) conical dies [4]
c) spherical dies [5]
Various modes of upsetting of prismatic and cylindrical
billets find their application in the analysis of formability
of materials. Upsetting with dies of various geometry are
presented on Fig.1. [1, 4, 5].
Determination of stress-strain state in the processes of
metal forming is one of the most important tasks of the
applied theory of plasticity. The knowledge of stressstrain enables determination of the process parameters
and analysis of material formability.
There are three groups of methods which enable stressstrain and forming load determination:



Theoretical
Experimental
Numerical
In this paper results obtained by numerical simulation of
upsetting of cylinder by V-shape dies in Simufact
Forming programming package and the results obtained
experimentally are presented.
Experimental part of the paper was conducted in the
Laboratory for Technology of Plasticity at the Department
of Production Engineering in Novi Sad. The upsetting of
prismatic billets made of steel C45E material was
performed by V-shape dies on Sack und Kiesselbach
hydraulic press of 6,3 MN rated force. Two series of
billets with square section were used.
2. NUMERICAL ANALYSIS OF UPSETTING
PRISMATIC BILLETS BY V-SHAPE DIES
Numerical analysis of upsetting of prismatic billets by Vshape dies was performed using the finite element method
in Simufact Forming v.10 programming package.
The finite elements method is modern method of
numerical analysis and represents a method of direct
analysis. Unlike the other numerical methods it is based
on physical discretization.
Fig.4. and Fig.5. shows stress distribution at the end of
upsetting process for billets series PH and PS. Maximum
die stroke for upsetting of the billet series PH was 20mm
and for series PS maximum die stroke was 17mm. It can
be concluded that maximum effective stress for series PH
in the end of the process is 1205MPa, Fig.4., and for
series PS that value is 1149MPa, Fig.5. It can be seen that
maximum effective stress in both series are concentrated
on the contact surface of the billets.
Fig.2. Upsetting by V-shape dies
On Fig.2. beginning of the process of upsetting of
prismatic billet by V-shape dies is given.
The dies and models used in simulation were modeled in
CAD package Solid Edge V18 and then imported to the
Simufact Forming program. Two series of billets were
used and initial dimensions are given on Fig.3. (a, b).
SlMesh Tetra mesher with 2mm element size was used,
Fig.3. (c). Dies used in simulation were set as rigid bodies
and press velocity was 1mm/s.
Fig.4. Distribution of effective stress for billets series PH
Fig.5. Distribution of effective stress for billets series PS
Series PH
a)
Series PS
b)
SlMesh Tetra
c)
Distribution of the effective stress inside the billets series
PH along x direction is given on Fig.6. and for billets
series PS on Fig.7. Planes, in which appropriate effective
stresses act, are 5, 10 and 15 mm offsitted from the
reference point in y direction for series PH and 4, 8 and
12mm for series PS. It can be seen that for both series
value of effective stresses decreases with increasing of x
coordinate.
Fig.3. Initial dimension of the billets
2.1. Simulation results
By 3D numerical simulation of upsetting of prismatic part
by V-shape dies the information on stress-strain state and
forming load diagram as function of die stroke were
obtained. In the simulation, the flow curve for C45E steel
determined by Rastagaev's technique and approximated
by the below equation was used:
k  289,671  668,779  ef0,3184 [ MPa]
(1)
where:
k -flow stress
ef -effective strain
Fig.6. Distribution of effective stress along x direction for
billets series PH
Friction between contact surface of dies and billet was
defined with coefficient of friction μ = 0,12.
Fig.8. shows distribution of effective plastic strain for
billets series PH. Distribution of effective plastic strain
for billets series PS is given on Fig.9.
upsetting was performed with coefficient of friction
μ = 0,12.
Fig.7. Distribution of effective stress along x direction for
billets series PS
From Fig.8. and Fig.9. it can be concluded that for both
series maximum plastic strain is concentrated on the
contact surface of billet. For billets series PH maximum
plastic strain is 1,681 and for billets series PS that value is
1,501.
Fig.10. Sack&Kiesselbach Hydraulic Press
Fig.11. shows billet series PH before and after
deformation. From Fig.11. can be seen that the shape of
the billets after deformation is the same as shape of billet
in the end of simulation process.
Fig.11. Billet series PH before and after deformation
Fig.8. Distribution of effective plastic strain for billet
series PH
In the end of the process the billet cracked. The crack
appeared on the both lateral sides of billet in y,z plane.
Upsetting of the billets series PH was performed with the
maximum die stroke of 20mm. From the diagram in
Fig.12. it can be concluded that the forming load obtained
by simulation is higher than in the experiment, and the
difference is approximately 6%. In the last phase, between
18mm and 20mm forming load obtained in simulation is
40% higher than forming load obtain experimentally.
Fig.9. Distribution of effective plastic strain for billet
series PS
Forming load diagram as function of die stroke is shown
on Fig.12. and Fig.14.
3. EXPERIMENTAL TEST OF FORMING
LOAD
Experimental test of changing of forming load depending
of the die stroke was conducted on Sack&Kiesselbach
hydraulic press of 6,3MN rated force (Fig.10.).
The billets compressed in the experiment were made from
C45E steel. Billets geometries performed in experiment
were identical to the ones used in simulation, Fig.3 (a, b).
The dies used in the experiment were polished and
Fig.12. F-s diagram for billets series PH
Billet from second series before and after deformation is
given on Fig.13. In the end of the process billet cracked.
Upsetting of the billets series PS was performed with the
maximum die stroke of 17mm. From Fig.13 it can be seen
that the shape of the billet after deformation is same as
shape of billet in the end of simulation process.
higher than the load obtained in experiment. It should be
mentioned that the maximum forming load obtained by
simulation is by 6%-18% higher than in experiment, and
in one moment that difference reaches 40%. Also, it can
be concluded that the effective plastic stress for billets in
both series decreases with increasing of x coordinate.
ACKNOWLEDGEMENT
This paper is a part of the investigation within the project
EUREKA E!5005 financed by Serbian Ministry of
Science and Technological Development. Authors are
very grateful for the financial support.
REFERENCES
Fig.13. Billet from series PS before and after deformation
Diagram on Fig.14. shows that during the entire process
the forming load obtained by simulation was negligible
higher than the load obtained by experiment.
From Fig.14. it can be concluded that the forming load
obtain by simulation and experiment is almost the same
after die stroke of 8mm, but then, from 8mm to the end of
the process forming load obtained by simulation is higher
than in experiment. Difference between forming load in
simulation and experiment in the end of the process is
approximately 18%.
[1] VILOTIĆ, D., SHABAIK, A.H. (1985) Analisys of
upsetting with profiling tools, Journal of Engineering
Materials and Technology, Vol. 107, pp. 261-264
[2] LIN, S.Y. (2002) Stress analysis of upsetting with
concave curve dies, Journal of Material Processing
Technology, Vol. 213, pp 59-68
[3] VILOTIĆ, D., VUJOVIĆ, V., PLANČAK, M.
(1994) Determination of contact stress in upsetting
of cylinder by cone-concave dies, Metallurgy and
New Materials Researches, Vol. II, No. 1-2, pp. 105113
[4] VILOTIĆ, D., PLANČAK, M., GRBIĆ, S.,
ALEXANDROV, S., CHIKANOVA, N. (2003) An
approcach to determining the workability diagram
based on upsetting test, Fatigue & Fracture of
Engineering Materials & Structures, Vol.26, pp 305310
[5] VILOTIĆ, D., CHIKANOVA, S., ALEXANDER, S.
(1999) Disc upsetting between spherical dies and its
aplication to the determination of forming limit
curves, Jurnal of Strain Analysis, Vol. 34, pp
[6] ROBERT, D. COOK Finite Element Modeling for
Stress Anlysis, University of Wiskonsin-Madison,
1995.
CORRESPONDENCE
Fig.14. F-s diagram for billets series PS
4. CONCLUSION
Upsetting processes occur as production phases in most
technologies for cold and warm bulk forming. They are
performed with tools which geometry often differs from
the standard plane geometry. Analysis of processes in
plastic forming technology requires the stress-strain state
to be determined as well as the basic process parameters.
For these reasons various method are used, e.g.
theoretical, experimental, numerical.
This paper presents a comparative view of results
obtained by simulation in Simufact Forming program
package and results obtained experimentally. For the
experiment and simulation V-shape dies and prismatic
billets are used.
From the analysis of presented results it can be concluded
that forming load obtained in simulation is negligible
Dragisa VILOTIC, PhD, University Professor, Faculty of
Technical Science, Trg Dositeja Obradovica 6, 21000
Novi Sad, Serbia, vilotic@uns.ac.rs
Miroslav PLANCAK, PhD, University Professor, Faculty
of Technical Science, Trg Dositeja Obradovica 6, 21000
Novi Sad, Serbia, plancak@uns.ac.rs
Sergej ALEXANDROV, PhD, Institute for Problems in
Mechanic, Russian Academy of Science, 101-1 Prospect
Vernadskogo,
119526
Moscow,
Russia,
sergei_alexandrov@yahoo.com
Aljosa IVANISEVIC, MSc, Research Assistant, Faculty
of Technical Science, Trg Dositeja Obradovica 6, 21000
Novi Sad, Serbai, aljosa@uns.ac.rs
Dejan MOVRIN, dipl. ing, University Assistant, Faculty
of Technical Science, Trg Dositeja Obradovica 6, 21000
Novi Sad, Serbia, movrin@uns.ac.rs
Mladomir MILUTINOVIC, Mr, University Assistant,
Faculty of Technical Science, Trg Dositeja Obradovica 6,
21000
Novi
Sad,
Serbia,
mladomil@uns.ac.rs