Applied Mechanics and Materials Vol. 758 (2015) pp 77-82 Submitted: 30.10.2014 © (2015) Trans Tech Publications, Switzerland Accepted: 17.11.2014 doi:10.4028/www.scientific.net/AMM.758.77
FEM Simulation of Machining AISI 1045 Steel Using Driven Rotary Tool
Yanuar Burhanuddin, Suryadiwansa Harun, Gusri Akhyar Ibrahim Department of Mechanical Engineering, University of Lampung, Lampung – Indonesia Email: yanuar.burhanuddin@eng.unila.ac.id Keyword: driven rotary tool, tool rotational speed, force, temperature Abstract.This study investigates the influences of driven rotary tool (DRT) on temperatures and forces when turning AISI 1045 steel. A set of cutting conditions was used in FE simulations to predict cutting force, stresses and temperatures developed at around the edge of tool. The material cutting speed ranges were set between 20 and 250 m min-1. The rotary tool speed were 0 and 100
rpm.. The feed rate and the depth of cut were
set constant. Simulation results provided the predicted cutting distribution of temperatures and stresses at the chip and work piece. Introduction Machining of high strength steel using conventional cutting is very difficult and time consuming. During machining takes place, temperature and pressure will arise, this will lead to hardening due to the deformation or phase change of the materials. Therefore, instead of using conventional cutting cutting tool, machining of high-strength steel
using a driven rotary tool
may provide
a
better solution.
Rotary tool turning is a cutting process in which the cutting edge of a round insert rotates its axis, so that a
continously
indexed cutting edge is fed into the cutting zone
[1].
There are two types of
rotaty tool,
self-propelled rotary tool (SPRT) and driven rotary tool
(DRT).
The
difference between these two types is an auxillary drive unit to rotate the driven tool [2]. In SPRT, tool rotates due to the rotation of the workpiece while the DRT, the tool rotates due to driver motor.
Self-rotation of a knife during machining process appears under influence of friction forces which appear in the point of contact of tool flank surface and machined surface. In the case of when angle
α=0°
then the knife during machining doesn’t rotate but when angle α≠
0°, a
substantial contribution to self-rotation of knife has friction of a moving chip on the rake face
[3]. In the rotary cutting tool, round inserts mounted on the tool holder will spin when
engagement of the workpiece and the
cutting
tool.
Because
the
rotary movement of the tool, the wear and heat will be distributed uniformly around the inserts. Uniform distribution of heat and wear at the cutting zone between the inserts and the workpiece will keep the temperature at an acceptable level. Thus hardening deformation or phase transformation can be avoided [1]. To obtain the characteristics of the rotary machining process, reseachers require a lot of machining experiments. The vast machining experiments require a lot of cost and time. This gives an idea to the researchers to use finite element analysis. Investigators prefer the finite element analysis compared the experimental work because it can save time and costs [4]. Research of machining process simulation using rotary cutting tool is very rare. Until now none of literature on researches of rotary tool machining is reported. Most of the machining simulation researches are non-rotary tool machining simulation. There are many unknown phenomena in the rotary tool machining such as temperature distribution, tool wear, tool/workpice stress and workpiece surface integrity. In this study a finite element is applied to simulate AISI 1045 steel machining using rotary tool. The aim of this study is to determine temperature distribution in the work-piece, tool and chip and cutting force in turning process. The model is based on unsteady state machining condistion. AISI 1045 steel were turned under various cutting conditions. Various
cutting conditions
are
cutting speed, feed rate, depth of cut
and tool rotational speed.
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103.3.46.247-10/03/15,05:41:31) Finite Element Modeling The first step in finite element simulation of rotary tool machining is to establish the tool geometry. This geometry model including rake angle, relief angle and tool diameter as shown in Fig 1. The next step is to establish
the finite element model of
rotary tool turning.
The
finite element model of rotary
tool is made
based on the
kinematic model of rotary turning. Kinematic and finite element model of rotary tool turning were illustrated in Fig 2a & b. Fig 1. Tool geometry model (d=tool diameter, h=tool thickness, α=rake angle, λ=clearance angle) (a) (b) Figure 2 (a) Kinematic modeling of rotary tool, (b) Meshing of rotary tool turning Finite element software was used to simulate
the metal cutting process.
It
is based on the
Updated Lagrangian formulation. This software is used to simulate machining parameters in a turning process of AISI 1045 carbon steel. Workpiece was assumed as plastic, whereas the tool was assumed as a rigid. The transfer of heat was taken into account to the modeling of cutting temperature. Simulation process was done by varying the
cutting speed, feed, depth of cut
and
tool
rotation speed.
The
machining parameters is shown in Table 1, while the type and geometry of material and tool are shown in Table 2. Table1. Machining parameters in simulation Tool rotary speed N, Rpm 0 ~ 3000 Workpiece cutting speed VW, m/min 60
~160 Feed, mm/rev 0.1;0.
2
Depth of cut a, mm 0.5 Inclination angle, deg
0o
Offset angle θ, deg 0
Applied Mechanics and Materials Vol. 758 79 Table 2. Material type and cutting tool geometry Workpiece Material type Plain Carbon Steel (AISI 1045) Material dimension Diameter 50 mm Round Tool Insert Material Uncoated tungsten carbide, WC- Co Geometry Jenis
RPMT 1604 MO-BB (Kyocera) Relief angle α=
11oC
Diameter D=16 mm
The results of force and temperature on tool and workpiece would be analyzed. The initial temperature of the workpiece and the tool was set to 20 °C. Simulation was carried out until achieved a steady state condition to allow the flow of heat into the workpiece, tool and chip. Results and values observed on the tool and workpiece would be taken into account after the complete simulation. Result and Discussion The results from the turning process simulation using rotary cutting tool were analyzed after the complete simulation. There are two aspects to be analyzed namely cutting temperature and cutting force. Of the total energy consumed in machining, nearly all of it (approximately 99%) is converted into heat [5]. The heat was distributed between three areas namely
tool, workpiece and chip during the machining process.
A significant proportion of the cutting energy is carried off with the chip hence the chip temperature usually higher than two other areas. The temperature distribution on the interface of the tool-workpiece is illustrated in Fig 3a. While the temperature distribution on the chip where the largest temperature observed in this area is
shown in Fig
3.b.
The
results
of the tool rotational speed
effect on the machining temperature and cutting force are shown in Table 3 and Table 4. Table 3 contains the
effect of tool rotational speed on the
tool- workpiece interface
temperature and
chip temperature. Table 4 contains
the effect of tool
rotational speed
on
the
main cutting force.
In both tables
it can be seen that the temperature
and
cutting
force at lowest value
when machining at
tool rotational
speed of 35 m /min.
Therefore based on the value of tool
cutting speed
35
m/min, the
prediction
of the effect of
workpiece
cutting speed
on the cutting force and
chip
temperature
will be simulated. (a) (b) Fig. 3 (a) temperature distribution on the interface of the tool-workpiece, (b) temperature distribution on the chip Table 3 The effect of tool rotary speed variation to tool-workpiece interface and chip temperature (Machining condition: Vw=150
m/min, f=0.2 mm/rev, a
= 1
mm,
i = 0, θ = 0, and dry) No Tool rotation speed Cutting temperature N, Rpm VT, m/min Tool-workpiece interface, oC Chip, oC 1. 0 0 432 787 2. 50 2.5 384 755 3. 100 5.0 377 724 4. 200 10 371 708 5. 300 15 392 716 6. 500 25 389 711 7. 650 32.5 347 752 8. 700 35 332 737 9. 750 37.5 324 689 10. 800 40 371 742 11. 900 45 375 754 12. 1000 50 378 751 13. 1500 75 408 758 14. 2000 100 419 775 15. 2500 125 414 794 16. 3000 150 546 1070 Table 4
The effect of
workpiece
cutting speed
variation to main
cutting
force (Machining condition: Vw=80
m/min, f=0.2 mm/rev, a = 0.5 mm,
i = 0, θ = 0, and dry) No N, Rpm Tool rotation speed VT, m/min Main cuuting force FY, N 1. 0 0 340,832 2. 100 5.0 367,820 3. 200 10 348,427 4. 300 15 364,161 continued.. 5. 500 25 354,084 6. 600 30 300,202 7. 700 35 281,639 8. 800 40 284,986 9. 1000 50 290,242 10. 1500 75 283,339 11. 2000 100 272,194 12. 2500 125 226,195 13. 3000 150 232,926 Table 5 and Fig. 4 show the result of workpiece cutting speed variation to main
cutting force and
chip
temperature
on
the following
machining condition: VT=35
m/min, f=0.
1
mm/rev, a = 0.5 mm,
inclination angle = 0, θ = 0, and dry.
At the cutting
tool
speed of
35
m/min, the cutting
force and cutting
temperature decrease
with the
increasing
of
cutting speed.
The cutting force
decrease from 200 N to 150 N. Decrease in cutting forces according to experiments conducted by Lei & Liu Applied Mechanics and Materials Vol. 758 81 [6]Decrease in cutting forces can be understood as the effect of
thermal softening and
reduced
friction due to the increase
in
cutting speed.
Thermal softening causes a decrease in strength of materials, the increase in friction angle and lower large plastic deformation [7]. But in this simulation cutting temperature
decreases with increase in cutting speed.
This is somewhat different from the usual obtained by other researchers. However, this temperature decrease is expected when going very rotating cutting tool wear in machining. Thus
using a
rotating
cutting tool
rotating
at a speed of
35 m / min can be used. Table 5
The effect of
workpiece
cutting speed
variation to main
cutting
force and chip temperature (Machining condition : VT=35
m/min, f=0.
1
mm/rev, a = 0 .5 mm,
i = 0, θ = 0, and dry) No Workpiece
cutting speed
Vw,
m/min Cutting force, N
Cutting temperature (chip), oC 1. 60 200 581 2. 80 200 575 3. 100 192 512 4. 120 150 540 5. 140 160 500 6. 160 150 520 250 Cutting Force, N 200 60 80 100 120 140 160 Cutting Temperature, oC 700 600 150 500 400 100 300 50 200 100 0 0 Cutting Speed, Vw 60 80 100 120 140 160 Cutting Speed, Vw (a) (b) Fig. 4
(a) Effect of
cutting
speed on
cutting forces,
(b) Effect of cutting speed on
chip temperature Conclusions The conclusions of this work
can be drawn as follows: 1.
The
cutting
force and cutting temperature are in lowest value at the tool rotary of speed of 35
m/min.
2.
The cutting
force
and cutting
temperature will decrease with the cutting speed increasing at tool
speed of
35
m/min.
Hence,
to
lower
the
temperature
of the
machining
at
high speed using driven rotary tool, the recommended tool rotational speed is 35 m / min. Acknowledgement The authors would like to thanks to The General Directorate of Higher Education, Indonesian Ministry of Education and Culture for sponsoring this work under Contract No. 582/UN26/8/PL/2013. References [1] Shuting Lei and Wenjie Liu, "High-speed machining of titanium alloys using the driven rotary tool," International Journal of Machine Tools & Manufacture, vol. 42, pp. 653-661, 2002. [2] Tero Stjenstoft, "Machining of some difficult-to-cut material with rotary cutting," The Royal Institut of Technology, KTH, Stockholm, Dissertation 2004. [3] Grzegorz Wieloch et al., "New Idea in construction and performance of turning rotary knife," Annals of Warsaw University of Life Sciences, vol. 72, pp. 433-437, 2010. [4] Ladislav Kandrac, Ildiko Mankova, Marek Vrabel, and Josef Beno, "Finite Element Simulation of Cutting Forces in Orthogonal Machining of Titanium Alloy Ti-6Al-4V," Applied Mechanics and Materials, vol. 474, pp. 192-199, 2014. [5] Mikell P. Groover, Fundamental of Modern Manufacturing Processes. New Jersey: John Wiley and Sons, 2007. [6] S. Lei and W. Liu, "High-speed machining of titanium alloys using the driven rotary tool," Int. Journal of Machine Tool & Manufacture, vol. 42, pp. 653-661, 2002. [7] J.P. Davim and C. Maranhao, "A study of plastic strain and plastic strain rate in machining of steel AISI 1045 using FEM analysis," Materials and Design, vol. 30, pp. 160-165, 2009. 78 Mechanical Engineering and Applied Mechanics 80 Mechanical Engineering and Applied Mechanics 82 Mechanical Engineering and Applied Mechanics
