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on-ferrous Metals. 2017. No. 2
on-ferrous Metals. 2017. No. 2
.
.
pp. 55–60
pp. 55–60
3D modelling of combined rolling-extrusion
of alloying rods of Al – Ti – B
UDC 621.777
Based on the finite element analysis for the combined rolling-extrusion process, the stress-strain state,
force on the tool, and the moments on the rolls are calculated as a function of the tool temperature and
the rotational speed of the rolls.
The calculations are performed for an Al – Ti – B system alloy containing 5% titanium and 1% boron,
widely used in the industry for melt modification when casting ingots of aluminum alloys. The authors
proposed ligature rods from this alloy to be produced by the method of combined rolling-extruding
(CRE), which has significant advantages in comparison with the traditional technologies of continuous
casting-rolling and discrete extruding. Therefore, for the design of technology and equipment for
combined processing, it is necessary to have preliminary design data on the temperature-velocity
conditions and energy-force parameters of the metal deformation process. For 3D modeling in a soft-
ware package SolidWorks
®
the model of the combined rolling-extruding process was created, which
was imported into the package DEFORM
TM
. The simulation process of producing a rod diameter of
9.5 mm by installing rolls with diameters of 462 mm and a protrusion stream 394 mm with rolling reduc-
tion of 50% drawing ratio during extruding 6.2 at the rotation speed of 9 rpm data obtained by the
temperature distribution metal, strain rates, normal contact stresses on the tool and internal stresses
in the metal. In addition, graphs of the change in the forces and moments of rolling acting on the rolls
are plotted, depending on the rotational speed of the rolls and the required power of the drive motor is
calculated. The obtained data were used in the design of new industrial equipment for combined rolling-
extruding of aluminum alloys and experimental studies, which confirmed the adequacy of the obtained
modeling results.
Key words: ligature, rolling-pressing, rolls, tension, speed, temperature, deformation, force.
DOI: 10.17580/nfm.2017.02.10
I. N. Dovzhenko, Assistant Professor, Chair of Metal Forming
1
N. N. Dovzhenko, Professor, Chair of Metal Forming
1
S. B. Sidelnikov, Professor, Head of the Chair of Metal Forming
1
R. I. Galiev, Assistant Professor, Chair of Metal Forming
1
, e-mail: gri1979@mail.ru
1
Siberian Federal University, Krasnoyarsk, Russia.
Introduction
I
n recent times, for production of long-length deformed
semi-finished products of aluminum alloys, new energy-
saving technologies of combined casting and metal
forming such as continuous casting-rolling and rolling-
extrusion, as well as continuous casting and rolling-extrusion
[1–4], have been actively used and applied. Their application
is particularly relevant for production of Al – Ti – B
alloying rods which are widely used in Russia and abroad
for inoculation of bars of aluminum alloys for the purpose
of fine-grain structure and reduction of gas porosity [5–8].
Rods made of Al – Ti – B alloy with 5% titanium and 1%
boron [9–16] are the most in demand for grain refinement.
The relevance of this ligature is also emphasized by the
fact that it was used for the preparation of new aluminum-
scandium alloys, casting large-sized ingots of them and
obtaining deformed semi-finished products with an increased
level of operational and mechanical properties in the course of
the project 03.G25.31.0265 “Development of economically
alloyed high-strength Al – Sc alloys for use in road transport
and navigation” within the framework of the Program for
the implementation of complex projects for the creation of
high-tech production, approved by the Government of the
Russian Federation dated April, 2010 № 218 [17].
On the basis of finite element analysis, for the process
of combined rolling-extrusion of a rod with a diameter
of 9.5 mm from Al – Ti — B alloy, calculations of the
change of stress-strain state, the forces acting on tools
and the torques of rolls depending on the temperature
of the tools and rotation speed of the rolls were made.
A software package DEFORM
TM
-3D was used for
3D modeling. The data of deformation resistance of
alloy AlTiB1 [3] was imported to the software package
DEFORM
TM
-3D.
Methodology
Geometric three-dimensional models of extrusion
components of a CRE unit and an aluminum feedstock
were built with a software package SolidWorks
®
(Fig. 1).
56
METAL PROCESSING
Then these geometries were imported in the format*.stl to
the software package DEFORM
TM
-3D.
The following data is selected as input modeling data.
1. Material of feedstock — aluminum alloy AlTiB1,
material of the rolls and the die — tool steel;
2. End product is an extruded product with a diameter
9.5 mm;
3. Parameters of the rolls and the die:
– pass width — 22 mm;
– feedstock dimensions — 20u20u500 mm;
– dimensions of the die face — 20u21 mm;
– reduction ratio during extrusion — 6.2;
– diameter of the roll with protrusion — 462 mm;
– diameter of the roll with a groove — 394 mm.
4. Rotation frequency of rolls from 4 to 14 rpm
5. The conditions of contact interaction of the
feedstock with the rolls were accepted according to the
friction law of Siebel with an index of friction during metal
deformation = 0.5 and for the die face = 0.2.
6. Percent reduction during rolling = 50%.
7. Initial temperature of feedstock Т
feed
= 575
о
С, heat
exchange with environment and the tools occurs;
8. Initial temperatures of the die Т
die
and the rolls
Т
roll
were measured from 100 to 300
o
С, heat exchange
with environment and feedstock occurs respectively. An
important factor affecting the value of stress state and
conditions of stable flow of rolling-extrusion process
is the temperature in plastic deformation zone and the
temperature of extruded rod.
The results of the research and their discussion
Fig. 2 shows temperature behavior in deformation
zone under the following conditions: T
roll
= Т
die
= 200
o
С,
Т
feed
= 575
o
С, rotation speed of rolls – 9 rpm. As can be
seen from picture 2 there is an intensive temperature drop
from 566
o
С down to 429
о
С in the area of rolling, then
the temperature slightly increases due to deformational
heating. Such temperature pattern has a significant
influence on stress state, as will be illustrated below.
Fig. 3 shows temperature change of an extruded pro-
duct Т
prod
at the exit of the die mouth depending on
2
3
Y
X
Z
5
4
1
572
P 1
P 3
P 11
543
488
458
429
0.000 67.9 136 17010233.9
515
12 34
5.00
Srain rate Effective ((mm/mm)/sec)
3.33
1.67
0.000
600
550
500
450
400
600
550
500
450
400
49
у = 377.55е
0.022x
R
2
= 0.961
у = 0.39x + 397.33
R
2
= 0.9946
14
n, rpm
0 100 200 300 400
T
roll
,
o
C
T
prod
,
o
C
a
b
Fig. 1. 3D model of combined rolling-extrusion (CRE) process
1 — the roll with a protrusion; 2 — the roll with a groove; 3 — the
die; 4 — a feedstock; 5 — the feed rolls
Fig. 2. Metal temperature behavior in deformation zone
Fig. 4. Deformation rate behavior during CRE:
1 — area of feedstock gripping; 2 — rolling area; 3 — pressing-out
area; 4 — extrusion area
Fig. 3. Impact of rotation frequency of the rolls (а) and temperature of
the tool (b) on temperature of extruded product
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on-ferrous Metals. 2017. No. 2
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pp. 55–60
pp. 55–60
rotation frequency of the rolls (Fig. 3, a) and temparature
of the rolls (Fig. 3, b). It is seen that with increase of
rotation frequency of the rolls, the temperature of product
at the exit of the die grows because deformation rate
increases (Fig. 4), resistance to deformation grows, and
therefore heat generation increases too. And the time for
heat transfer between the metal and the rolls decreases,
consequently the temperature drop of the feedstock in the
area of rolling and pressing-out decreases.
Analysis of the dependences shows it is possible to
control thermal conditions by regulating the temperature
of the rolls and the die through their initial heating and
subsequent cooling during combined rolling-extrusion.
Moreover, the product temperature can be reduced by
reducing rotation frequency of the rolls.
Analysis of deformation rates at T
roll
= Т
die
= 200
o
С,
Т
feed
= 575
o
С and rotation frequency of the rolls 9 rpm
shows that in the areas of gripping and rolling, deforamtion
rate is not higher than 2.5
–1
. In the section of the roll
centers, defromation rate decreases down to 0.1–0.3 s
–1
,
further in the area of pressing-out the rate has a slight
increase, and then suddenly it reaches its maximum values
up to 130 s
–1
in the area of extrusion.
The behavior of deformation rates and temperatures
under the same parameters impacts distribution of both
contact stresses (Fig. 5, a) affecting on the rolls and the die,
and internal stresses in the metal (Fig. 5, b–d). Analysing
the data one can note that in the areas of gripping and
rolling of the feedstock, an increase of normal contact
stresses is observed, and the stresses reach their maximum
values in the plane passing through the common axis of
the rolls.
In the area of pressing-out, normal contact stresses at
first decrease and then increase, thus significantly non-
monotone character of their change along the deformation
zone is observed. This can be explained by non-monotone
character of deformation along the deformation zone, and
also by the fact that in the area of pressing-out the effect of
active and reactive friction forces increases. In the area of
pressing-out, the stresses reach their upper value.
Analysis of axial stresses in metal (Fig. 5, b–d) showed
a constant increase of stresses
х
up to the extrusion
area, and their decrease in the area of rod outflow from
the extrusion area. Behaviour of stresses
y
repeats
nonmonotone distribution of normal contact stresses.
Stresses
z
change also non-monotonically and have
maximum values in the area of extrusion.
As it appears from the analysis of stress distribution, a
very favourable pattern of the stress state is formed during
rolling-extrusion which is confirmed by the diagram of
distribution of average normal stress (Fig. 6).
Based on the data it can be concluded that during
extrusion of metal by combined method of rolling-
Y
X
Z
300
0.000
–37.5
0.000
–25.0
–50.0
–75.0
–100
–125
–150
–175
–200
0.000
–25.0
–50.0
–75.0
–100
–125
–150
–175
–200
–75.0
–113
–150
–188
–225
–263
–300
200
100
0.000
0.000
Min
421
Max
Normal pressure (MPa)
a
с
d
b
Stress X (MPa)
Stress Y (MPa)
Stress Z (MPa)
Fig. 5. Distribution of normal contact stresses on the tool (а) and internal stresses in metal along axes Х (b), Y (c), Z (d)
0
, MPa
–150
–100
–150
–200
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Relative coordinate of deformation zone, x/L
Fig. 6. Change of average normal stress along deformation zone
58
METAL PROCESSING
extrusion, an additional type of deformation appears —
alternating deformation in which every elementary
volume of metal first undergoes vertical deformation and
horizontal deformation of elongation, and after passing
the minimum roll gap, the deformation of opposite sign.
Such deformation behavior contributes to creation of
a favourable pattern of stress state and higher ductility,
especially of as cast metal, and also increase of the
maximum allowable extrusion rate [1–3].
When modeling the force actions during combined
rolling-extrusion, the rolls and the die were put into
coordinate system so that the direction of rolling and
extrusion would be opposite to the direction of axis ОХ
(see picture 1). Forces affecting on the rolls and the die
along axes X, Y, Z were calculated in Deform™-3D for
such system.
Fig. 7 shows variation graphs of forces on the rolls
and the die depending on the time of the process at the
following conditions:
200
60
50
1
2
40
30
20
10
0
P
BY
, kN
P
BX
, kN
150
100
50
0
у = –2x + 173.13
R
2
= 0.9995
у = –0.64x + 36.827
R
2
= 0.9685
у = –0.44x + 50.627
R
2
= 0.9891
468
10
12 14
46 8
10
12 14
n, rpm
n, rpm
a
b
100
10
8
6
4
2
0
80
60
40
20
0
P
MX
, kN
M, kN
.
m
у = –0.74x + 88.193
R
2
= 0.9939
у = –0.18x + 8.8533
R
2
= 0.9838
у = –0.16x + 7.74
R
2
= 0.9552
468
10
12 14
468
10
12 14
n, rpm
n, rpm
a
b
1
2
1
5.52
4.41
3.31
2.21
1.1
0 0.628 1.26 1.88 2.51 3.14
Time, s
N
.
10
4
N
1.14
.
10
5
1.29
.
10
5
1.04
.
10
4
7.77
.
10
4
5.18
.
10
4
2.59
.
10
4
9.09
.
10
4
6.82
.
10
4
4.54
.
10
4
2.27
.
10
4
N
a
b
c
Fig. 8. Variation graphs of forces acting on rolls РВY (a) and РВX (b)
depending on rotation frequency of the rolls:
1 — a roll with a groove; 2 — a roll with a tongue
Fig. 9. Variation graphs of force РМХ (a), acting on die, and moments
(b) of the rotational speed of the rolls:
1 — a roll with a groove; 2 — a roll with a tongue
Fig. 7. Variation graphs of forces on the rolls and the die depending on
time:
a — along axis X; b — along axis Y; c – along axis Z
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pp. 55–60
pp. 55–60
T
r
= Т
d
= 200
o
С, Т
feed
= 575
o
С, rotation frequency
of the rolls — 9 rpm.
Fig. 8 shows dependences of forces acting on the rolls
along axis ОY (Р
ВY
) and ОХ (Р
ВХ
) on initial temperature
of the feedstock, the tools and rotation frequency of the
rolls. With increase of rotation speed of the rolls, the
temperature of the feedstock falls in the areas of rolling
and pressing-out. It causes decrease of forces acting on
the rolls and along axis ОY, at the same time force Р
ВY
is
practically identical for both of the rolls.
Along axis ОХ, force Р
ВX
is acting on the rolls, which
leads to undesired displacement (separation) of the rolls.
The value of this force for the roll with a groove is 1.4–
1.6 times higher than for the roll with a tongue. It can
cause uneven “pressing-back” (detachment) of the rolls
from the die resulting in metal getting into a gap between
them.
For secure CRE process it is necessary to know during
designing of CRE plants, the value of force РМХ acting
on the die along axis ОХ and distribution of torques on
the rolls. Fig. 9 shows dependence of the force and the
torques acting on the rolls with a groove and with a tongue
upon rotation frequency of the rolls. Analysis of the
dependences at Т
feed
= 575
o
С and at rotation frequency
of the rolls 9 rpm shows that the value of torque for the roll
with a groove is different from the value of torque for the
roll with a tongue which is explained by different effective
diameter of rolls. Maximum values of torques should be
taken into account during design of a pinion stand and
selection of gearboxes and motors.
Based on the obtained results the required power Ndm
of a drive motor was calculated considering the efficiency
coefficient of a gearbox (0.96) and a pinion stand (0.95).
The obtained dependences on rotation frequency of the
rolls and temperature of the tools are shown in Fig. 10.
Conclusion
Thus, in the program complex Deform™ 3D for the
adopted conditions for the combined treatment of an Al –
Ti – B alloy with 5% titanium and 1% boron, modeling was
performed and the temperature of the resulting product
was obtained from the speed of rotation of the rolls and the
temperature of the tool; forces and stresses acting on the
instrument; moments on the rolls and the required power
of the drive motor. These results of the calculation are
confirmed by the data of experimental studies [1–4] and
were used later in the design of technology and equipment
for combined rolling-extrusion of aluminum alloys.
*
E. V. Gladkov took part in this work.
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and magnesium. Moscow : MISIS, 2002. 376 p.
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COMINTECH, 2005. 365 p.
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of TiB
2
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Materials Transactions B. 2016. Vol. 47, Iss. 6. pp. 3285– 3290.
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25
20
15
10
5
20
15
10
5
0
468101214
0 100 200 300 400
T
r
,
o
C
N
dm
, kN
у = 1.23x + 2.2967
R
2
= 0.9989
у = –0.0085x + 15.1
R
2
= 0.9653
a
b
n, rpm
Fig. 10. Variation diagram of the required power of a drive motor
depending on rotation frequency of the rolls (a) and temperature
of the roll (b)