EXPERIMENTAL INVESTIGATION AND NUMERICAL SIMULATION … · Analytical and Numerical Tools -30- The...
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Proceedings of the 6th International Conference on Mechanics and Materials in Design,
Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Az
PAPER REF: 5371
EXPERIMENTAL INVESTIGATION ANDOF THE EXTRUSION DRILLING AND TAPPING PROCESS
Sigitas Kilikevičius1(*), Ramūnas Česnavičius1Department of Mechanical Engineering, Kaunas University of Technology, Kaunas, Lithuania
2Department of Production Engineering, Kaunas University of Technology, Kaunas, Lithuania
(*)Email: [email protected]
ABSTRACT
This paper presents an experimental investigation and numerical simulation of holes drilling
and threads tapping in thin-walled plates by using special tungsten carbide and HSS tools.
This technique is called as extrusion drilling and tapping, because the hole and the thread are
formed without chip removal. A review of the literature dealing with the analysed problem
was conducted as well as the experimental setup for extrusion drilling and tapping
experiments was described. The experiments were performed on DC
Ti-6Al-4V alloy sheets along with a numerical simulations using finite element analysis
software ABAQUS.
Keywords: thin plate, friction, drilling, tapping, numerical simulation.
INTRODUCTION
Thread machining is widely used process in various industries; however, sometimes it is
complicated due to insufficient thickness of the blank, for example in thin
order to produce a required thread length, an additional insert wel
increase the overall thickness of the wall. For this reason, non
tapping methods are used. One of them is extrusion or friction drilling and tapping by using
special tungsten carbide and HSS tool
metal becomes plastic due to significantly increased temperature in the drilling zone caused
by the friction between the tool and the workpiece and, as a consequence, the tool penetrates
the workpiece material. At that time, the tool forms an additional molten flange like a neck on
the underneath side of the sheet, which later can be frictionally tapped using a special tapper.
The main stages of extrusion drilling and tapping are shown in Fig.
a b c d e f
Fig. 1 - Extrusion drilling and tapping stages: a
c – material flow and hole forming; d
f
Proceedings of the 6th International Conference on Mechanics and Materials in Design,
Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Azores, 26-30 July 2015
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INVESTIGATION AND NUMERICAL SIMULATION OF THE EXTRUSION DRILLING AND TAPPING PROCESS
Ramūnas Česnavičius1, Povilas Krasauskas2,
Department of Mechanical Engineering, Kaunas University of Technology, Kaunas, Lithuania
Department of Production Engineering, Kaunas University of Technology, Kaunas, Lithuania
This paper presents an experimental investigation and numerical simulation of holes drilling
walled plates by using special tungsten carbide and HSS tools.
extrusion drilling and tapping, because the hole and the thread are
formed without chip removal. A review of the literature dealing with the analysed problem
was conducted as well as the experimental setup for extrusion drilling and tapping
described. The experiments were performed on DC-06, AISI 304 steel and
alloy sheets along with a numerical simulations using finite element analysis
friction, drilling, tapping, numerical simulation.
Thread machining is widely used process in various industries; however, sometimes it is
complicated due to insufficient thickness of the blank, for example in thin
order to produce a required thread length, an additional insert welding operation is required to
increase the overall thickness of the wall. For this reason, non-traditional drilling and tread
tapping methods are used. One of them is extrusion or friction drilling and tapping by using
special tungsten carbide and HSS tools without cutting edges. Applying this method, the
metal becomes plastic due to significantly increased temperature in the drilling zone caused
by the friction between the tool and the workpiece and, as a consequence, the tool penetrates
rial. At that time, the tool forms an additional molten flange like a neck on
the underneath side of the sheet, which later can be frictionally tapped using a special tapper.
The main stages of extrusion drilling and tapping are shown in Fig. 1.
a b c d e f
Extrusion drilling and tapping stages: a – initial contact; b – former-tip penetration into the material;
material flow and hole forming; d – former withdrawal; e – fast travel of the tapper to the workpiece;
f – extrusion tapping; g – tapper withdrawal
NUMERICAL SIMULATION OF THE EXTRUSION DRILLING AND TAPPING PROCESSES
Department of Mechanical Engineering, Kaunas University of Technology, Kaunas, Lithuania
Department of Production Engineering, Kaunas University of Technology, Kaunas, Lithuania
This paper presents an experimental investigation and numerical simulation of holes drilling
walled plates by using special tungsten carbide and HSS tools.
extrusion drilling and tapping, because the hole and the thread are
formed without chip removal. A review of the literature dealing with the analysed problem
was conducted as well as the experimental setup for extrusion drilling and tapping
06, AISI 304 steel and
alloy sheets along with a numerical simulations using finite element analysis
Thread machining is widely used process in various industries; however, sometimes it is
complicated due to insufficient thickness of the blank, for example in thin-walled parts. In
ding operation is required to
traditional drilling and tread
tapping methods are used. One of them is extrusion or friction drilling and tapping by using
s without cutting edges. Applying this method, the
metal becomes plastic due to significantly increased temperature in the drilling zone caused
by the friction between the tool and the workpiece and, as a consequence, the tool penetrates
rial. At that time, the tool forms an additional molten flange like a neck on
the underneath side of the sheet, which later can be frictionally tapped using a special tapper.
a b c d e f g
tion into the material;
fast travel of the tapper to the workpiece;
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The literature review on the subject showed that numerical simulation of friction drilling is
conditioned by a lot of conventionalities and uncertainties as well as highly depends on
various factors such as material properties, cutting regimes, geometrical parameters of tools,
etc. (Lee, 2008; Miler, 2007; Krasauskas, 2012). Therefore, a numerical simulation of
extrusion drilling for each new material is complicated and specific. Since this method is a
recently new metal machining method, the extrusion drilling process still is not investigated
deep enough. In the time, the chipless tapping process of threads in holes formed by extrusion
drilling has not been investigated yet using numerical methods. Therefore, the purpose of this
work was to carry out an extrusion drilling and tapping experiment along with a numerical
simulation, as well as to verify the results.
EXPERIMENTAL TECHNIQUE OF THE EXTRUSION DRILLING AND TAPPING
DC-06, AISI 304 steel and Ti-6Al-4V alloy plates with 1.5 mm in thickness, which were cut
from sheet metal, were used for the experimental investigation of the extrusion drilling and
tapping processes. The mechanical properties of the materials are presented in Table 1.
Table 1 - Mechanical material properties
Material
Tensile strength,
ultimate, MPa
Tensile strength,
yield, MPa
Elongation at
break, %
Modulus of
elasticity, GPa
DC-06 370-350 170-180 41 201
AISI304 515-708 205-340 40 193
Ti-6Al-4V 1170 1100 10 114
The experiments were carried out on a CNC milling machine “DECKEL MAHO DMU-35M”
with a “Sinumerik 810D/840D” controller and “ShopMill” software using a tungsten carbide
fluteless drill with a diameter of 5.2 mm and an M6×1 HSS fluteless tapper. The experimental
setup is shown in Fig. 2.
a b c
Fig. 2 - Experimental setup of the friction drilling and tapping experiments: a – general view of the setup;
b – hole drilling experiment; c – tapping experiment
The axial force and torque were measured using a universal laboratory charge amplifier
Kistler type 5018A and a press force sensor Kistler type 9345B mounted on the CNC table.
Measuring ranges of the sensor: -10…10 kN for force, -25...25 Nm for torque; sensitivity: ≈-
3.7 pC/N for force, ≈-200 pC/Nm for torque. The amplifier converts the charge signal from
the piezoelectric pressure sensor into a proportional output voltage. The variation of the axial
drilling force and torque was recorded to a computer using a “PICOSCOPE 4424”
Proceedings of the 6th International Conference on Mechanics and Materials in Design,
Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Azores, 26-30 July 2015
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oscilloscope and “PicoScope 6” software. The drilling temperature on the upper side of the
plate at the contact zone was measured using a “Fluke574” optical pyrometer (measuring
range: -30…900°C; accuracy: ±0.75% of reading; response time 250 ms) and recorded to the
computer as well.
The matrix of the drilling and tapping experiments is presented in Table 2.
Table 2 - Matrix of the drilling and tapping experiments
Material
Plate
thickness,
mm
Drilling Tapping
Spindle speed,
rpm
Tool feed rate,
mm/min
Spindle speed,
rpm
Tool feed
rate, mm/rev
Mild steel DC-06
1.5
2000/2500/3000 140
100
1
2000/2500/3000 100
2000/2500/3000 60
AISI304 stainless steel 1.5 2000/2500/3000 100
Ti-6Al-4V titanium alloy 1.5 2000/2500/3000 100
RESULTS AND DISCUSSION OF THE EXPERIMENTAL INVESTIGATION
The experiment showed that drilling parameters, such as the tool rotational speed and the feed
rate have a significant influence on the axial force and torque variation.
In order to investigate the influence of feed rate on the drilling force, DC-06 steel plates were
drilled under feed rates of 60, 100 and 140 mm/min. The results showed that an increase in
the feed rate results an increase in the axial force (Fig. 3).
Fig. 3 - Experimental drilling axial force and torque variation when spindle speed is
2000 rpm under different feed rates
The results of the investigation under different spindle speed are presented in Fig. 4. An
analysis of the experimental results showed that the axial force, during the drilling process
(from the initial contact until the end of the hole forming) varies in a very wide range. It was
defined, that the axial force reaches its maximum value when the conical part of the tool fully
penetrates into the plate. When the sheet is pierced, the axial force drastically decreases,
meanwhile the torsion moment increases. The maximum torque is reached when the conical
part of the tool is fully penetrated into the plate. It is seen from the figure that an increase of
the spindle speed leads to a decrease of both the axial force and the torque.
It was observed that the tapping force values are very low (less than 90 N), therefore these
results were not presented and discussed. The variation of the tapping torque is presented in
Fig. 5. The negative value of the torque starting at about 7 s represents the tapper withdrawal
stage when it is rotating in the reversed direction. When the spindle speed is 2000 m, the
0
200
400
600
800
1000
1200
0 1 2 3 4 5 6 7 8 9 10
Axi
al d
rillin
g f
orc
e,
N
Drilling time, s
F60 mm/min
F100 mm/min
F140 mm/min
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maximum torque is obtained between 1 and 2
torque was several times higher than the drilling torque.
a b
Fig. 4 - Experimental drilling axial force and torque variation during hole forming when feed rate
100 mm/min: a
Fig. 5 - Experimental tapping torque variation during thread tapping of
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maximum torque is obtained between 1 and 2 s, after that it gradually decreases. The tapping
torque was several times higher than the drilling torque.
a b
c
Experimental drilling axial force and torque variation during hole forming when feed rate
a – DC-06 steel; b – AISI 304 stainless steel; c – Ti-6Al
Experimental tapping torque variation during thread tapping of steel DC-06,
AISI 304 and Ti-6Al-4V alloy
s, after that it gradually decreases. The tapping
Experimental drilling axial force and torque variation during hole forming when feed rate is
6Al-4V alloy
06, stainless steel
Proceedings of the 6th International Conference on Mechanics and Materials in Design,
Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Azores, 26-30 July 2015
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MATHEMATICAL BACKGROUND OF EXTRUSION DRILLING AND TAPPING SIMULATION
During friction drilling and tapping, heat is generated from two sources: plastic energy
dissipation due to the shear deformation and heating due to the friction in the tool and
workpiece contact zone.
The heating from the friction between the tool and the workpiece is the main heat source and
comprises 98-99% of the total heat, therefore the heat transfer during tool penetration into
workpiece is described (Miler, 2007):
2 2 2
2 2 2x y z f
T T T Tc k k k q
t x y zρ
∂ ∂ ∂ ∂= + + + ∂ ∂ ∂ ∂
& , (1)
where ρ is the material density; c is the specific heat, T is the temperature, t is the time, k is
the heat conductivity in x, y, and z are the coordinates; fq& is the heat generated by the friction
between the tool and the workpiece, it is expressed:
0
fT
f fq dTω= ∫& , (2)
where ω is the angular velocity of the tool and Tf is the friction moment in the contact zone.
For the finite element method simulation the temperature and strain rate dependent Johnson-
Cook model was used (Johnson, 1983). In this case, the flow stress is expressed:
( )( )0
1 1
mn pl tran
pl
melt tran
A B Clnε θ θ
σ εε θ θ
− = + + − −
&
&, (3)
where parameter A is the initial yield strength of the material at room temperature, B is the
hardening modulus; C is the parameter representing strain rate sensitivity; plε is the effective
plastic strain; plε& is the effective plastic strain rate 0ε& is the reference strain rate; n is the strain
hardening exponent; m is the parameter which evaluates thermal softening effect, θ is
temperature, meltθ and tranθ are material the melting and transition temperatures.
A failure criterion is required to characterize the material properties degradation due to the
tool penetration into the material. The Johnson–Cook failure model based on the plastic strain
was used in this study. In this model, failure occurs when the parameter D reaches a value of
1:
1
pl
f
D d .εε
= ∫ (4)
The equivalent strain to fracture fε is defined by (Johnson, 1985):
( )3
1 2 4 5
0
1 1
pd
pl
f d d e d ln dσε
ε θε
− = + + +
&
&, (5)
where d1 to d5 are material constants, which can be determined from experiments, p is the
hydrostatic pressure, i.e. the third of the trace of the Cauchy stress tensor.
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FINITE ELEMENT SIMULATION OF THE EXTRUSION DRILLING AND TAPPING PROCESSES
The simulation of the extrusion drilling and tapping was carried out on a Ti-6Al-4V alloy
plate with a thickness of 1.5 mm and an AISI 304 steel plate with the same thickness, using
ABAQUS/EXPLICIT finite element analysis software. The computational model
incorporating the workpiece, the former and the tapper is shown in Fig. 6. The workpiece was
created as a disk of 18 mm diameter and 1.5 mm thickness.
a b
Fig. 6 - Computational model of drilling (a) and tapping (b)
One of the primary difficulties in the simulation is the excessive mesh distortion in the plunge
phase, so ABAQUS/EXPLICIT finite element code based on the adaptive mesh technique,
allows automatically regenerate the mesh when the elements due to large deformation are
distorted. The adaptive meshing technique in ABAQUS/ EXPLICIT creates a new mesh and
remaps the solution parameters from the existing mesh to the newly created mesh. In this
study, the adaptive meshing was carried out for every three increments and five mesh sweeps
per adaptive mesh increment was performed. The drill and the workpiece was meshed using
element type C3D8RT, which has 8-node tri-linear displacement, temperature and reduced
integration with hourglass control. A global element size of 0.3 mm was used to mesh the
workpiece. An element size of 0.15 mm was used in the centre of the workpiece where the
tool penetrates the material. 10 layers of elements through the thickness were generated in the
workpiece. The mesh of the workpiece contained 89710 elements. The tapper was meshed
using element type C3D4T due to its complex shape.
In order to save computational time, the mass scaling technique that modifies the densities of
the materials in the model and improves the computational efficiency was used. In this study,
mass scaling was performed every 10 increments to obtain a stable time increment of at least
0.0001 s step time.
It was assumed that the drill and the tapper are rigid and adiabatic, the frictional contact is
described by Coulomb’s friction law with the constant coefficient of friction and 100% of
dissipated energy caused by the friction between the parts was converted to heat. The
coefficient of friction was set to 0.05.
The boundary conditions (Fig. 6) were set as follow: the outer surface of the workpiece was
fixed in all degree of freedom; the top and bottom surfaces of the workpiece were under free
convection with the convection coefficient of 30 W/m2K; the ambient air temperature and the
initial temperature of the workpiece were set to 295 K (22ºC).
Material properties and the Johnson-Cook parameters used for the simulation of the drilling
and tapping processes are presented in Table 3 (Fronta´n, 2012; Lesuer, 2000).
f1
ω2
ω1
f2
Proceedings of the 6th International Conference on Mechanics and Materials in Design,
Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Azores, 26-30 July 2015
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The Jonson-Cook material damage parameters used in the simulation for AISI 304 were as
follow: d1 = 0.69, d2 = d3 = d5 = 0, d4 = 0.0546 (Fronta´n, 2012). Accordingly, for Ti-6Al-4V:
d1 = -0.09, d2 = 0.25, d3 = -0.5, d4 = 0.014, d5 = 3.87 (Lesuer, 2000).
Table 3 - Material properties and the Johnson-Cook parameters
Parameter Units AISI 304 Ti-6Al-4V
Young modulus, E GPa 207.8 113.8
Poisson‘s ratio, ν - 0.3 0.342
Density, ρ N/m3 8000 4430
Melting temperature,meltθ K 1673 1878
Specific heat capacity J/(kgK) 452 526.3
Thermal expansion, L
α 10-6
K-1
17.8 10.6
Initial yield strength A MPa 280 1098
Hardening modulus B MPa 802.5 1092
Strain hardening exponent n - 0.622 0.93
Thermal softening exponent m - 1.0 1.1
Strain rate constant C - 0.0799 0.014
Reference strain rate 0ε& 1/s 1.0 1.0
RESULTS OF THE SIMULATION AND COMPARISON TO THE EXPERIMENTS
The simulation showed that the maximum temperature is reached during the drilling stage
when the conical part of the tool penetrates the workpiece (Fig. 7c), it reaches up to 1642 K
(1369ºC) at that moment for Ti-6Al-4V alloy, when ω1=3000 rpm, feed ratio f1=100 mm/min,
and 1180 K (907ºC) for AISI 304 steel. The temperature is up to 1270 K (997ºC) in the final
stage of the drilling (Fig. 7d) for Ti-6Al-4V alloy and 969 K (696ºC) for AISI 304 steel.
a b
c d
Fig. 7 - Workpiece temperature (units are in K) drilling Ti-6Al-4V alloy at various distances of tool travel:
a – 1.5 mm; b – 3 mm; c – 7.86 mm; d – 12 mm
The temperature variation on the upper side of the workpiece at the contact zone is shown in
Fig. 8.
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Fig. 8 - Temperature on the upper side of the workpiece at the contact zone drilling AISI
The surface temperature variation of the simulation was obtained from the identical position
where the surface temperature was measured in the experiments. T
value on the upper side of the workpiece at the contact zone obtained by simulation was
589ºC. The simulation and the experiments both showed very similar results.
The shape of the neck and the equivalent plastic strain after the fin
shown in Fig. 9a, and the same after the thread is tapped
obtained on the Ti-6Al-4V alloy plate, under the following regimes:
mm/min for drilling and ω2=100 rpm and
information for the AISI 304 alloy plate is presented in Fig.
a b
Fig. 9 - Equivalent plastic strain in the final stag
Ti-6Al-4V alloy plate,
a b
Fig. 10 - Equivalent plastic strain in the final stage of drilling (a) and after the thread is ta
AISI 304 steel plate,
The shape of the workpiece deformation during drilling and tapping was close to the actual
one obtained by the experiment.
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Temperature on the upper side of the workpiece at the contact zone drilling AISI
The surface temperature variation of the simulation was obtained from the identical position
where the surface temperature was measured in the experiments. The maximum temperature
value on the upper side of the workpiece at the contact zone obtained by simulation was
589ºC. The simulation and the experiments both showed very similar results.
The shape of the neck and the equivalent plastic strain after the final stage of drilling are
9a, and the same after the thread is tapped – in Fig. 9b. These results were
4V alloy plate, under the following regimes: ω1=3000 rpm,
=100 rpm and f2=1 mm/rev for tapping. Accordingly, the same
304 alloy plate is presented in Fig. 10.
a b
Equivalent plastic strain in the final stage of drilling (a) and after the thread is tapped (b) in the
4V alloy plate, ω1=3000 rpm, f1=100 mm/min, ω2=100 rpm and f2=1
a b
Equivalent plastic strain in the final stage of drilling (a) and after the thread is ta
304 steel plate, ω1=3000 rpm, f1=100 mm/min, ω2=100 rpm and f2=1
The shape of the workpiece deformation during drilling and tapping was close to the actual
one obtained by the experiment.
Temperature on the upper side of the workpiece at the contact zone drilling AISI 304 steel
The surface temperature variation of the simulation was obtained from the identical position
he maximum temperature
value on the upper side of the workpiece at the contact zone obtained by simulation was
589ºC. The simulation and the experiments both showed very similar results.
al stage of drilling are
9b. These results were
=3000 rpm, f1=100
or tapping. Accordingly, the same
e of drilling (a) and after the thread is tapped (b) in the
=1 mm/rev
Equivalent plastic strain in the final stage of drilling (a) and after the thread is tapped (b) in the
mm/rev
The shape of the workpiece deformation during drilling and tapping was close to the actual
Proceedings of the 6th International Conference on Mechanics and Materials in Design,
Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Az
The comparison of the experimental an
Fig. 11, while for Ti-6Al-4V alloy
Fig. 11 - Comparison of the experimental and simulation results is presented for drilling (a) and tapping (b)
Proceedings of the 6th International Conference on Mechanics and Materials in Design,
Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Azores, 26-30 July 2015
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The comparison of the experimental and simulation results for AISI 304 steel is presented in
4V alloy - in Fig. 12.
Comparison of the experimental and simulation results is presented for drilling (a) and tapping (b)
AISI 304 steel, f1=100 mm/min
4 steel is presented in
Comparison of the experimental and simulation results is presented for drilling (a) and tapping (b)
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Fig. 12 - Comparison of the experimental and simulation results is presented for drilling (a) and tapping (b)
The comparison of the experimental and simulation results for tapping is presented in Fig.
The profiles of the experimental and simulated force and torque variations were quite similar,
therefore it is possible to conclude that the presumptions taken in the simulation are correct
and realistically describe the extrusion drilling and tapping processes. The com
model could be useful for prediction of reasonable extrusion drilling and tapping regimes.
However, in order to get more precise results and a better agreement between the
experimental and simulation results, the computational model could be imp
more realistic friction model along with taking into account the tool temperature and
deformations.
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Comparison of the experimental and simulation results is presented for drilling (a) and tapping (b)
Ti-6Al-4V alloy, f1=100 mm/min
The comparison of the experimental and simulation results for tapping is presented in Fig.
f the experimental and simulated force and torque variations were quite similar,
therefore it is possible to conclude that the presumptions taken in the simulation are correct
and realistically describe the extrusion drilling and tapping processes. The com
model could be useful for prediction of reasonable extrusion drilling and tapping regimes.
However, in order to get more precise results and a better agreement between the
experimental and simulation results, the computational model could be imp
more realistic friction model along with taking into account the tool temperature and
Comparison of the experimental and simulation results is presented for drilling (a) and tapping (b)
The comparison of the experimental and simulation results for tapping is presented in Fig. 13.
f the experimental and simulated force and torque variations were quite similar,
therefore it is possible to conclude that the presumptions taken in the simulation are correct
and realistically describe the extrusion drilling and tapping processes. The computational
model could be useful for prediction of reasonable extrusion drilling and tapping regimes.
However, in order to get more precise results and a better agreement between the
experimental and simulation results, the computational model could be improved by using a
more realistic friction model along with taking into account the tool temperature and
Proceedings of the 6th International Conference on Mechanics and Materials in Design,
Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Az
Fig. 13 - Comparison of the experimental and simulation results
CONCLUSIONS
An experimental analysis and a numerical simulation of extrusion drilling and tapping plates
of various materials were carried out and the axial force and torque variations were measured
under different drilling and tapping regimes.
The analysis of the experimental results s
process (from the initial contact until the end of the hole forming) varies in a very wide range.
It was detected, that the axial force reaches its maximum value when the conical part of the
tool fully penetrates into the plate. When the plate is pierced, the axial force drastically
decreases, meanwhile the torsion moment increases. The maximum torque is reached when
the conical part of the tool is fully penetrated into the sheet. An increase of the spindle sp
leads to a decrease of both the axial force and the torque, while an increase in the feed rate
results an increase in the axial force. The tapping process experimental investigation showed
that the tapping torque is several times higher than the drilli
is very low compared to the drilling force.
The simulation showed that the maximum temperature in the workpiece is reached during the
drilling stage when the conical part of the tool penetrates the workpiece. Under the fol
drilling regime: ω1=3000 rpm,
for Ti-6Al-4V alloy and 1180 K (907ºC) for AISI
(997ºC) in the final stage of the drilling for Ti
steel. The variation of temperature on the upper side of the workpiece at the contact zone
obtained by the simulation and the experiments was very similar.
The comparison of the experimental and simulation results leads to the conclusion that the
presumptions taken in the simulation are correct and realistically define the friction drilling
Proceedings of the 6th International Conference on Mechanics and Materials in Design,
Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Azores, 26-30 July 2015
-39-
omparison of the experimental and simulation results for tapping, ω2=100 rpm and
lysis and a numerical simulation of extrusion drilling and tapping plates
of various materials were carried out and the axial force and torque variations were measured
under different drilling and tapping regimes.
The analysis of the experimental results showed that the axial force, during the drilling
process (from the initial contact until the end of the hole forming) varies in a very wide range.
It was detected, that the axial force reaches its maximum value when the conical part of the
ates into the plate. When the plate is pierced, the axial force drastically
decreases, meanwhile the torsion moment increases. The maximum torque is reached when
the conical part of the tool is fully penetrated into the sheet. An increase of the spindle sp
leads to a decrease of both the axial force and the torque, while an increase in the feed rate
results an increase in the axial force. The tapping process experimental investigation showed
that the tapping torque is several times higher than the drilling torque while the tapping force
is very low compared to the drilling force.
The simulation showed that the maximum temperature in the workpiece is reached during the
drilling stage when the conical part of the tool penetrates the workpiece. Under the fol
=3000 rpm, f1=100 mm/min, it is up to 1642 K (1369ºC) at that moment
4V alloy and 1180 K (907ºC) for AISI 304 steel. The temperature is up to 1270 K
(997ºC) in the final stage of the drilling for Ti-6Al-4V alloy and 969 K (696ºC) for AISI
steel. The variation of temperature on the upper side of the workpiece at the contact zone
obtained by the simulation and the experiments was very similar.
The comparison of the experimental and simulation results leads to the conclusion that the
ons taken in the simulation are correct and realistically define the friction drilling
=100 rpm and f2=1 mm/rev
lysis and a numerical simulation of extrusion drilling and tapping plates
of various materials were carried out and the axial force and torque variations were measured
howed that the axial force, during the drilling
process (from the initial contact until the end of the hole forming) varies in a very wide range.
It was detected, that the axial force reaches its maximum value when the conical part of the
ates into the plate. When the plate is pierced, the axial force drastically
decreases, meanwhile the torsion moment increases. The maximum torque is reached when
the conical part of the tool is fully penetrated into the sheet. An increase of the spindle speed
leads to a decrease of both the axial force and the torque, while an increase in the feed rate
results an increase in the axial force. The tapping process experimental investigation showed
ng torque while the tapping force
The simulation showed that the maximum temperature in the workpiece is reached during the
drilling stage when the conical part of the tool penetrates the workpiece. Under the following
mm/min, it is up to 1642 K (1369ºC) at that moment
304 steel. The temperature is up to 1270 K
4V alloy and 969 K (696ºC) for AISI 304
steel. The variation of temperature on the upper side of the workpiece at the contact zone
The comparison of the experimental and simulation results leads to the conclusion that the
ons taken in the simulation are correct and realistically define the friction drilling
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and tapping process. The computational model could be useful for prediction of rational
frictional drilling and tapping regimes in order to lower drilling forces and, as a consequence,
to decrease tool wear and extend the lifetime of tools.
REFERENCES
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