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Finite-element-analysis of the effect of different wiper tool edge geometries during the hard turning of AISI 4340 steel
Simulation Modelling Practice and Theory 94 (2019) 250–263
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Simulation Modelling Practice and Theory journal homepage: www.elsevier.com/locate/simpat
Finite-element-analysis of the effect of different wiper tool edge geometries during the hard turning of AISI 4340 steel Langlang Jiang, Dazhong Wang
T
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Shanghai University of Engineering Science, Shanghai 201620, China
ARTICLE INFO
ABSTRACT
Keywords: Wiper tool Tool edge geometry Finite element method (FEM) Cutting force
This paper investigates the performance of different wiper tool edge geometries in machining of AISI 4340 steel using finite element method (FEM) simulation. The cutting process is simulated with Arbitrary Lagrangian–Eulerian (ALE) approach in AdvantEdge. The purpose is to explore the effects of wiper tool geometries on cutting performance of AISI 4340 steel compare with conventional tool. We explored the cutting force, residual stress, Mises stress and distribution of temperature, and the chip shape also be examined. The simulation results suggest that wiper tools can increase cutting force and peak cutting temperature compare with experimental result, but it can reduce the temperature of distribution in the cutting edge which is beneficial to reduce the wear of tool. At the same time, the wiper tools also have a great influence on chip shape and stress.
1. Introduction Hard turning (HT) is a major metal cutting process for reducing the workpiece diameter to the specified size and producing smooth surface finish on workpiece materials with hardness greater than 48 HRC without grinding. With the development of machining technology, hard turning instead of grinding has achieved obvious economic benefits. The popularity of hard turning is mainly due to its ability to generate complex geometric surfaces with better shape accuracy and better tolerances in one process [1]. It is widely used in the processing of AISI 4340 because of its characteristics of high processing efficiency, clean processing technology, less investment in equipment and high overall processing precision. The hard turning process of alloy steel requires greater cutting force and cutting temperature than the process of normal steel. Therefore, it is necessary to do more research on hard turning in order to meet the rapid development of production requirements. In recent years, the wiper tool has been widely used in hard turning. The wiper edge is the transition between the primary and secondary cutting edges and is actually the extreme form of the secondary cutting edge. It mainly serves to increase the impact resistance of the tool tip and reduce the surface roughness value of the workpiece. Rocha et al. [2] optimized the turning process of AISI H13 hardened steel by using PcBN wiper tool and obtained optimal turning process conditions. Kumar et al. [3] presented a study of such research contributions, mechanics of material removal, finite element analyses, associated challenges and possible remedies related to hard turning with wiper geometry tool. Addona et al. [4] made a comparison of turning operation using conventional turning tool, wiper inserted geometry tool and grinding process on the basis of surface roughness. The results indicate that feed rate has significant role to play in producing lower surface roughness followed by cutting speed. Grzesik and Wanat [5] presented a comparative study on surface finish generated in a hard turning using conventional and wiper ceramic inserts. According to
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Corresponding author. E-mail address: [email protected] (D. Wang).
https://doi.org/10.1016/j.simpat.2019.03.006 Received 24 October 2018; Received in revised form 27 February 2019; Accepted 18 March 2019 Available online 19 March 2019 1569-190X/ © 2019 Published by Elsevier B.V.
Simulation Modelling Practice and Theory 94 (2019) 250–263
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these authors, keeping equivalent feed rates, 0.1 mm/rev for conventional and 0.2 mm/rev for wiper inserts. O¨ zel et al. [6] indicate that the smaller average surface roughness (Ra) is attainable with wiper tools. Davim et al. [7] evaluated machinability turning AISI D2 hardened steel with ceramic tools using statistical techniques, and their tests show that with the appropriated choice of cutting parameters it is possible to obtain a surface roughness (Ra < 0.8 mm) that allows cylindrical grinding operations to be eliminated. Guddat et al. [8] made a analysis of surface integrity in hard turning using wiper inserts compared with conventional inserts. They found that the application of PCBN wiper inserts leads to reduce surface roughness and higher compressive residual stresses. Aouici et al. [9] described a comparison of machining forces and flank wear between wiper ceramic (multi radii) and conventional ceramic cutting tools in dry hard turning of cold work tool steel AISI 4140 (60 Hardness Rockwell Cone (HRC)). It is revealed that the uncoated ceramics performs better than the coated ceramics with reference to machining forces. On the contrary, wiper ceramic cutting tools have the better performance compared with conventional ceramic cutting tools, in particular, the flank wear. Mun˜ ozSa´ nchez et al. [10] found that all types of wear lead to increased residual stress when compared with the reference geometry, being this one of the undesired effects of tool wear during machining operations. Mohammadpour et al. [11] found that with increasing cutting speed and feed rate the maximum value of tensile residual stresses were increased. Gaitonde et al. [12] studied the influence of cutting speed, feed rate, and machining time on machinability aspects such as specific cutting force, surface roughness, and tool wear in AISI D2 cold work tool steel hard turning with wiper tool, the results showed that the wiper ceramic inserts are desirable for achieving a better surface finish and lesser specific cutting force as compared with conventional insert. Suresh et al. [13] analyzed the influence of cutting speed, feed rate, depth of cut and machining time on machinability characteristics such as machining force, surface roughness and tool wear during turning of AISI 4340 high strength low alloy steel using coated carbide inserts. They inferred that tool wear can be minimized by employing lower values of cutting speed, feed rate, depth of cut and machining time. Liu et al. [14] studied the influence of tool edge and tool wear on the residual stress distribution of hard steel turning of bearing steel. The results obtained in this study show that the tool nose radius affects the residual stress distribution significantly. Capello et al. [15] established an empirical relationship between residual stress and process parameters. Navas et al. [16] studied the effect on the final surface stress state in AISI 4340 steel of cutting speed, feed, tool nose radius, geometry of the tool chip breaker and coating of the cutting tool. The wiper of length is 1.1–1.5 times of feed. Fig. 1 illustrates four major types of edge preparation design used in most commercial cutting inserts: conventional tool (sharp edge and hone edge), arc wiper and line wiper. Usually, the shape of the wiper blade is arc and line. Fig. 2 illustrates schematic diagram of the geometry of conventional tools and wiper tools: (a) Arc wiper tool The radius r of the tool tip is increased to improve the smoothness of the machined surface and the durability of the tool. However, it also increases the grinding force and is prone to vibration. For high speed grinding steel turning tools, r is 0.5–5 mm, for carbide turning tools, r is 0.5–2 mm. When fine turning, r takes a small value, and when rough turning, it takes a large value. For general ordinary lathes, the value does not exceed 2 mm. It can be seen from Fig. 2 that the common blade and the wiper blade of the same basic size have the following dimensional relationships: (1)
= Kr x = (r2
r1)(1
cos ) = (r2
r1)(1
(2)
cosKr )
where r1 is tool nose radius, r2 is wiper blade connects the large arc radius of the tool tip and the secondary cutting edge, O1 is center of the arc of the tool tip, O2 is center of large arc, Kr′ is secondary declination of the tool. (b) Line wiper tool When the arc transition edge is not easy to grind or symmetrical, a straight line wiper can be used. When the length of the wiper is 0.5–2 mm, the off angle is usually about half of the lead angle. It can be seen from Fig. 2 that the common blade and the wiper blade of the same basic size have the following dimensional relationships:
Fig. 1. Wiper tool of edge shape. 251
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Fig. 2. Schematic diagram of the geometry of conventional hone edge tools and wiper tools (a) Line wiper tool and (b) Arc wiper tool.
bs = (r1
r2)tanKr +
(r2
r1)(1 cosKr + x cosKr ) sinKr cos Kr
(3)
the tool nose angle is θ, the relationship between Δr and Δx is as follows: (4)
x = rsin( /2) 2. Numerical simulation 2.1. Numerical approach and boundary conditions
Numerical simulation of the cutting process can provide detailed results for process variables, such as stress, strain, strain rate and temperature which are extremely difficult to measure with current technology. The undeformed mesh geometry in the case of new tool, presenting the main characteristics of the model is shown in Fig. 3 developed by Mun¨ oz-Sa´ nchez et al. [10]. Regions 1–3 combine sliding and Lagrangian/Eulerian boundaries and region 4 Eulerian. The tool was fixed and the cutting speed was applied to the workpiece. Cutting force took place in the plane 1–2 under plane strain conditions. Continuous chip formation was assumed. The depth of the workpiece was selected taking into account the typical profile of machined induced residual stresses. On the other hand, it is important to note that the dimensions of the undeformed chip (curvature radius and width) are not critical, thus, changes in these magnitudes can lead to successful calculations with the model. The metal cutting process can be regarded as a two-dimensional orthogonal cutting model when simulating the cutting process by using the FEM. the rake angle is 10∘ and the clearance angle is 6∘. The material employed in this work is AISI 4340 steel in normalized state. The chemical composition of this steel measured by X-ray fluorescence (XRF) analysis is gathered in Table 1. The mechanical properties for AISI-4340 steel are given in Table 2.
Fig. 3. Implementation of boundary condition and type of contour in the model. 252
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Table 1 The main chemical composition of AISI4340 steel [16]. C
Mn
P
S
Si
Cr
Mo
Ni
0.425
0.81
0.015
0.0058
0.31
0.83
0.25
1.80
Table 2 Material properties for the workpiece and tool [17]. Material properties
Workpiece
Tool
Material Young’s modulus (GPa) Hardness (HRC) Density (Kg m3) Poisson’s ratio
AISI 4340 208 48 7830 0.3 44.5
CBN 587
Thermal Conductivity (W m Specific heat (J kg
1∘C 1)
1 ∘C 1 )
Thermal expansion coefficient(∘C
0.13 44
477
1)
1.23 × 10
750
4.7 × 10
6
6
The AdvanteEdge is used for display dynamics analysis. In order to better reflect the hard-cutting process, the workpiece size is 5 mm × 2 mm in the cutting simulation model. The cutting edge radius of the tool is 4 µm, the rake angle is 10∘, the back angle is 6∘, the cutting speed is 100 mm/s, and the workpiece material is the ductile material AISI 4340. The material has been studied in depth and the simulation provides reliable calculation parameters. In this paper, Johnson–Cook model is employed to describe material model. The mechanical properties and Johnson–Cook parameters for AISI-4340 steel are given in Table 3 and the normal form which can be found below [18]. The model is suitable for describing the viscoplasticity of materials with temperature and the hardening characteristics of materials under large strain rates. It is very suitable as a constitutive model for cutting materials. The relationship is as follows:
= A + B ¯ pn
T* =
T Tm
1 + Cln
¯e p ¯0
1
T *m
(5)
Tr Tr
(6)
where A is the yield strength, B is the hardening modulus, C is the sensitivity coefficient of the material to the equivalent plastic strain rate, m is the softening coefficient affected by temperature, n is the hardening coefficient, ¯0 is the reference strain rate, Tm is the melting point, Tr is the conversion temperature which equals to room temperature. A, B, C, n and m are material constants. 2.2. The force and stress model The cutting force has an important influence on the cutting process, which directly affects the cutting temperature. It also leads to faster tool wear which affects the quality of the machined surface, and even causes deformation and vibration of the workpiece and the tool. At the same time, the cutting force is also the main basis for the energy consumption of the computer bed. It has great significance on the design and production of machine tools, fixtures and tools. Chou et al. [19] investigated the effect of tool nose radius on finish turning of hardened AISI 52,100 steels. Surface finish, tool wear, cutting forces, and, particularly, white layer (phase transformation structures) were evaluated at different machining conditions. Results show that large tool nose radius only give finer surface finish, but comparable tool wear compared to small nose radius tools. Specific cutting energy slightly increases with tool nose radius. The two-dimensional orthogonal model facilitates finite element numerical simulation analysis, which helps people to understand the internal mechanism of metal cutting. It is a powerful tool for studying chip shape, cutting heat, residual stress, tool wear and process parameter optimization. It can be seen from Fig. 4. In the rake face, where Fn is normal force, Ff is friction force, Fr is the joint force. In the shear plane, where Fns is positive pressure, Fs is shear force, Fr′ is the joint force. AD represents the sectional area of the cutting layer, As represents the sectional area of the shearing surface, and τ represents the shear stress on the shearing surface. Fp and Fc represent the cutting fore component. The relationship of each parameter is as follows: Table 3 Johnson–Cook model parameters for workpiece material AISI 4340. A/MPa
B/MPa
C
m
n
Tm/K
Tr/∘C
792
510
0.014
1.03
0.26
1793
20
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Fig. 4. The balanced system of cutting force.
AD = hD bD As = AD /sin Fr = Fs /cos( + Fc = Fr cos( ) Fp = Fr sin( )
(7)
)
Fs /cos( + ) = AD /sin cos( + ) Fr cos( ) = AD cos( )/sin cos( + ) = AD sin( )/sin cos( + Fr sin(
(8)
) )
(9)
Surface roughness is an important machining performance measure, especially in finish hard turning operation. Venkatasubbaiah Kambagowni et al. [20] discusses the impact of workpiece hardness, feed and depth of cut on Arithmetic mean roughness (Ra), root mean square roughness (Rq), mean depth of roughness (Rz) and total roughness (Rt) during the hard turning. Matsumoto et al. [21] made a effect of hardness on the surface roughness of AISI4340 was studied. The results show that hardness is an important factor affecting the surface roughness of the machined surface. Esteves Correia and Paulo Davim et al. [22] considered the influence of the wiper inserts when compared with conventional inserts on the surface roughness obtained in turning. The results show finish machining with wiper inserts provide a similar roughness when compared with machining with a low feed rate using conventional inserts. The well-known ideal surface roughness equation, which represents the best possible finish that may be obtained for a given tool shape and feed is given by the following geometric expression:
Ra =
fn 2
(10)
8re
where f represent feed andre represent tool nose radius. As is shown above, it can be known that reducing the feed rate or increasing the radius of the tool tip can reduce the surface roughness value, but reducing the feed rate will reduce the production efficiency, and increasing the tool nose radius will increase the cutting force. The large feed rate will reduce the surface roughness, so the design of the smoothing edge structure can be used to reduce the surface roughness. The shape of the wiper blade includes a circular arc shape, a linear shape, a straight line and a circular arc shape, and the principle is to reduce the surface roughness with a very small Kr′ value. 3. Experimental work In this work, a bar made of AISI 4340 mould steel was turned in orthogonal mode on a CA6140 processing lathe, and the cutting force was measured in each case. Fig. 5 shows the cylindrical bar of 50 mm diameter and 700 mm length made of AISI 4340 alloy steel which is used for the experiment. In every set of tests, we use a grinding machine to polish the cutting edge of the CBN tool. Different wiper blades with lengths of lab and arc radius of rbc were used to process AISI 4340 steel. The primary rake angle of the tool was 10∘ in all cases. A chip load of 0.1 mm and a cutting speed of 100 m/min were adopted. More details of the experimental work can be found in Table 4. 254
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Fig. 5. Experiment equipment. Table 4 Tool edge geometry in cutting tests with carbide tools. Case
Nose radius(mm)
Cutting speed(v)m/min
Feed(rev/min)
Depth of cut(d)(mm)
lab
rcd
Sharp edge tool Conventional tool Arc wiper tool Line wiper tool
0 0.2 0.2 0.2
100 100 100 100
0.1 0.1 0.1 0.1
1 1 1 1
0 0 0 0.2
0 0 0.8 0
4. Results and discussion 4.1. Temperature distribution The cutting temperature problem is an important parameter for studying high-speed machining, which has a great influence on tool wear, tool life, surface quality, machining efficiency and part accuracy. Shihab et al. [23] investigated the effect of cutting parameters (cutting speed, feed rate and depth of cut) on the cutting temperature in hard turning of AISI 52,100 alloy steel. Cui et al. [24] found that feed rate and depth of cut had greater effects on the maximum value of heat flux in saw-tooth chip formation than they did on the minimum value. The peak machined surface temperature occurred along the intersection of cutting edge and the machined surface. Its magnitude was mainly determined by the shear plane heat source and further increased due to flank face frictional heat source [25]. As is shown in Fig. 6, wiper tools have great influence on temperature distribution, the line wiper tool and sharp edge tool produced approximate higher peak temperature and temperature regions in the first deformation zone. While the hone edge tool and arc wiper tool produced approximate lower peak temperature and temperature regions in the tip of tool. Fig. 7 (a) shows the temperature profiles of the rake face and the flank face during hard turning, the part of (1) is distribution of flank face and the part of (2) is the distribution of rake face. We can find that wiper tool can reduce the temperature of flank face compared with conventional tool, but wiper tool caused the temperature of the rake face to rise. This is because the wiper tool has a lager radius of the arc of the tool and increases the contact area between the chip and the tool, so large cutting force causes an increase in temperature. we can also draw similar conclusions in Fig. 7 (b). 4.2. Comparative analysis of force Cutting force refers to the cutting force that is equal in magnitude and opposite in direction acting on the workpiece and the tool during the cutting process. Generally speaking, during cutting, the workpiece material resists the resistance generated when the tool is cut. Bartarya et al. [26] observed that radial force seems to be dominant in hard turning which makes it different from the conventional machining but effective investigation about force and friction conditions are still to be taken up. We extracted the simulated data and the experimental data for comparison which can be seen Fig. 8. It is seen in the Fig. 8, the simulated cutting forces show good agreement with the measured data. We can find that the wiper tool has a certain influence on both main cutting force and thrust force, and arc wiper tool has a great influence on cutting force compare with line wiper tool. Both wiper tools increase the cutting force. The arc wiper tool increases by approximately 8% of the main cutting force compare with conventional hone edge tool and line wiper tool increases by approximately 4% of the main cutting force compare with conventional hone edge tool. The arc wiper tool increases by approximately 19% of the thrust force compare with conventional hone edge tool and line wiper tool reduces by approximately 16% of the thrust force compare with conventional hone edge tool. We can also get similar conclusions from [27] and [28]. The common conclusion they draw is that the wiper tool has a larger cutting force during machining compare with conventional tool.
255
Fig. 6. Temperature distribution of the (a) sharp edge tool (b) hone edge tool (c) arc wiper tool (d) line wiper tool during hard turning.
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Fig. 7. Temperature distribution of the (a) rake face and flank face (b) peak temperature during turning.
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Fig. 8. The effect of different tools on cutting force of (a) Main cutting force and (b) Thrust force.
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Fig. 9. Crimp degree of different chips produced by different tool.
L. Jiang and D. Wang
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Table 5 Crimp degree of different chips produced by different tool. Chip size
(a)Sharp edge tool
(b)Hone edge tool
(c)Arc wiper tool
(d)Line wiper tool
H L H/L
0.91 0.60 1.516
0.54 0.79 0.683
O.53 0.64 0.843
0.64 0.80 0.80
4.3. Effect on the chip shape The chip formation process is of great significance for ensuring processing quality, reducing manufacturing costs and increasing productivity. Because various physical phenomena during cutting, such as cutting forces, cutting heat, tool wear and machining quality, are based on the chip formation process. Zhu et al. [29] presented an experimental study on the 3D chip morphology properties during orthogonal turn-milling of Al6061-T6 and discussed the effects of cutting parameters on turn-milling chip length and thickness. We describe the effect of the wiper by analyzing the degree of curling of the chips after cutting. We define a method for measuring the degree of chip curl. The distance between the tangent of the highest point of the chip curl and the unprocessed surface is H, and the distance between the tangent of the widest point of the chip curl and tangent point (chip and the tool) is L. The degree of curl of the chip is judged according to the distance H and L. The smaller the H and L, the greater the degree of curling of the chips, conversely, the smaller the degree of curling. In Fig. 9, we can find that the wiper has a significant effect on changing the chip shape. Grzesik [30] explored the wear development on wiper Al2O3–TiC mixed ceramic tools in hard machining of high strength steel. It found that wear of tool flank faces are mainly concentrated on the tool corner and the active secondary cutting (trailing) edge. So the study of chip shape is good for us to better understand the wear of the tool. The chip produced by arc wiper tool with a large degree of curl, and the curl radius is small and the chip is separated from the tool rake face early, which reduces the chip contact area. The friction reducing effect is obvious, which increases the heat convection of the air and the tool and reduce the cutting temperature. Both Fig. 9 and Table 5 show arc wiper tool produces chips with a high degree of curling. We can also get similar conclusions from Fig. 7. 4.4. Stress analysis On the machined surface, the tensile residual stresses decrease with an increase the edge radius and increase with an increase the cutting speed. However, below the surface, the compressive residual stresses increase with an increase the depth of cut. The stresses could directly affect fatigue life, corrosion resistance and component distortion. Therefore, it is necessary to analyze the stress distribution after machining the workpiece. It can be seen in Fig. 10, we can find that Mises stress is mainly concentrated at the tip position and the first deformation zone. Fig. 11 shows the effect of different tool edge shape on Mises stress and residual stress. As is shown Fig. 11(a), we explored the effect of the wiper tool on alloy steel AISI 4340 about Mises stress. We can find that wiper tools have little influence on Mises stress compare with conventional hone edge tools, but compared to sharp edge tools, the wiper tools can greatly reduce Mises stress. It can be seen in the Fig. 11 (b), the wiper tool produces a high residual stress near the machined surface. We can also get similar conclusions from [8], they found that the application of PCBN wiper inserts leads to reduce surface roughness and higher compressive residual stress. 5. Conclusions This paper uses the finite element method to simulate the orthogonal cutting process of AISI 4340 steel with several different wiper edges, and the cutting temperature, machining force, chip shape and stress during the machining process are compared. The following conclusions can be derived: (a) The wiper tool can reduce the temperature of flank face compared with conventional tool, but wiper tool caused the temperature of the rake face to rise. This is because the wiper tool has a lager radius of the arc of the tool and increases the contact area between the chip and the tool, so large cutting force causes an increase in temperature. Compared to conventional hone edge tool, the arc wiper tools increase the cutting temperature by 4% and the line wiper tool increase cutting temperature by 8%. (b) Both wiper tools can increase the cutting force. The arc wiper tool increases by approximately 8% of the main cutting force compare with conventional hone edge tool and line wiper tool increases by approximately 4% of the main cutting force compare with conventional hone edge tool. The arc wiper tool increases by approximately 19% of the thrust force compare with conventional hone edge tool and line wiper tool reduces by approximately 16% of the thrust force compare with conventional hone edge tool. (c) The wiper tools have a great influence on the degree of curling of the chip. The arc wiper blade forms a chip with a large degree of curling, which makes the chip and the rake face separate earlier, which is beneficial to reduce the wear of the rake face. (d) Wiper tools also have influence on Mises stress and residual stress. We can find that the wiper tool can increase the Mises stress by about 43% compare with conventional hone edge tool, and can significantly reduce Mises stress compare with sharp edge tool. The wiper tool produces a high residual stress near the machined surface. 260
Fig. 10. Stress distributions for(a) Sharp edge tool (b) Conventional hone edge tool (c) Arc wiper tool and (d) Line wiper tool.
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Fig. 11. Comparison of different tool edge shape of (a) Mises stress and (b) Residual stress after turning.
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References [1] J. Kundrák, B. Karpuschewski, K. Gyani, V. Bana, A.O.H. turning, J. Mater. Process. Technol. 202 (2008) 328–338. [2] L.C.S. Rocha, A.P. de Paiva, P.R. Junior, P.P. Balestrassi, P.H.d.S. Campos, Robust multiple criteria decision making applied to optimization of AISI h13 hardened steel turning with PCBN wiper tool, Int. J. Adv. Manuf. Technol. 89 (2016) 2251–2268. [3] A. Kumar, S.K. Pradhan, Investigations into hard turning process using wiper tool inserts, Mater. Today 5 (2018) 12579–12587. [4] D.M. DAddona, S.J. Raykar, Analysis of surface roughness in hard turning using wiper insert geometry, Procedia CIRP 41 (2016) 841–846. [5] W. Grzesik, T. Wanat, Surface finish generated in hard turning of quenched alloy steel parts using conventional and wiper ceramic inserts, Int. J. Mach. Tools Manuf. 46 (15) (2006) 1988C1995. [6] T. özel, Y. Karpat, L. Figueira, J.P. Davim, Modelling of surface finish and tool flank wear in turning of AISI d2 steel with ceramic wiper inserts, J. Mater. Process. Technol. 189 (2007) 192C198. [7] J.P. Davim, L. Figueira, Machinability evaluation in hard turning of cold work tool steel (d2) with ceramic tools using statistical techniques, Mater. Des. 28 (2007) 1186C1191. [8] J. Guddat, R. M’Saoubi, P. Alm, D. Meyer, Hard turning of AISI 52100 using PCBN wiper geometry inserts and the resulting surface integrity, Procedia Eng. 19 (2011) 118–124. [9] H. Aouici, M. Elbah, M.A. Yallese, B. Fnides, I. Meddour, S. Benlahmidi, Performance comparison of wiper and conventional ceramic inserts in hard turning of AISI 4140 steel: analysis of machining forces and flank wear, Int. J. Adv. Manuf. Technol. 87 (2016) 2221–2244. [10] A.M. noz Sánchez, J.A. Canteli, J.L. Cantero, M.H. Migulez, Numerical analysis of the tool wear effect in the machining induced residual stresses, Simul. Model. Pract. Theory 19 (2011) 872–886, https://doi.org/10.1016/j.simpat.2010.11.011. [11] M. Mohammadpour, M.R. Razfar, R.J. Saffar, Numerical investigating the effect of machining parameters on residual stresses in orthogonal cutting, Simul. Model. Pract. Theory 18 (2010) 378–389, https://doi.org/10.1016/j.simpat.2009.12.004. [12] V.N. Gaitonde, S.R. Karnik, L. Figueira, J.P. Davim, Performance comparison of conventional and wiper ceramic inserts in hard turning through artificial neural network modeling, Int. J. Adv. Manuf. Technol. 52 (2010) 101–114. [13] R. Suresh, S. Basavarajappa, V.N. Gaitonde, G.L. Samuel, Machinability investigations on hardened AISI 4340 steel using coated carbide insert, Int. J. Refract. Met. Hard Mater. 33 (2012) 75–86. [14] M. Liu, J.I. Takagi, A. Tsukuda, Effect of tool nose radius and tool wear on residual stress distribution in hard turning of bearing steel, J. Mater. Process. Technol. 150 (2004) 234–241. [15] E. Capello, Residual stresses in turning: part i: influence of process parameters, J. Mater. Process. Technol. 160 (2005) 221–228. [16] V.G. Navas, O. Gonzalo, I. Bengoetxea, Effect of cutting parameters in the surface residual stresses generated by turning in AISI 4340 steel, Int. J. Mach. Tools Manuf. 61 (2012) 48–57. [17] S. Agrawal, S.S. Joshi, Analytical modelling of residual stresses in orthogonal machining of AISI4340 steel, J. Manuf. Processes 15 (2013) 167–179. [18] D.I. Lalwani, N.K. Mehta, P.K. Jain, Extension of oxley’s predictive machining theory for johnson and cook flow stress model, J. Mater. Process. Technol. 209 (2009) 5305–5312. [19] Y.K. Chou, H. Song, Tool nose radius effects on finish hard turning, Journal of Materials Processing Tech 148 (2004) 259–268. [20] V. Kambagowni, R. Chitla, S. Challa, Determining the effect of material hardness during the hard turning of AISI4340 steel, J. Inst. Eng.India (2018). [21] Y. Matsumoto, Effect of hardness on the surface integrity of AISI 4340 steel, Trans. ASME J. Eng. Ind. 108 (1986) 169–175. [22] A.E. Correia, J.P. Davim, Surface roughness measurement in turning carbon steel AISI 1045 using wiper inserts, Measurement 44 (2011) 1000–1005. [23] S.K. Shihab, Z.A. Khan, A. Mohammad, A.N. Siddiqueed, RSM Based study of cutting temperature during hard turning with multilayer coated carbide insert, Procedia Mater. Sci. 6 (2014) 1233–1242. [24] X. Cui, J. Guo, Effects of cutting parameters on tool temperatures in intermittent turning with the formation of serrated chip considered, Appl. Therm. Eng. 110 (2017) 1220–1229. [25] L. Chen, B.L. Tai, R.G. Chaudhari, X. Song, A.J. Shih, Machined surface temperature in hard turning, Int. J. Mach. Tools Manuf. 121 (2017) 10–21. [26] G. Bartarya, S.K. Choudhury, State of the art in hard turning, Int. J. Mach. Tools Manuf. 53 (2012) 1–14. [27] J.P. Davim, L. Figueira, Comparative evaluation of conventional and wiper ceramic tools on cutting forces, surface roughness and tool wear in hard turning AISI d2 steel, J. Eng. Manuf. 221 (4) (2007) 625C633. [28] V.N. Gaitonde, S.R. Karnik, L. Figueira, J. Paulo, Davim, machinability investigations in hard turning of AISI d2 cold work tool steel with conventional and wiper ceramic inserts, Int. J. Refract. Met. Hard Mater. 27 (2009) 754–763. [29] L. Zhu, X. Jin, C. Liu, Experimental investigation on 3d chip morphology properties of rotary surface during orthogonal turn-milling of aluminum alloy, Int. J. Adv. Manuf. Technol. (2015), https://doi.org/10.1007/s00170-015-7758-y. [30] W. Grzesik, Wear development on wiper Al2O3CTic mixed ceramic tools in hard machining of high strength steel, Wear 266 (2009) 1021–1028, https://doi.org/ 10.1016/j.wear.2009.02.010.
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Simulation Modelling Practice and Theory journal homepage: www.elsevier.com/locate/simpat
Finite-element-analysis of the effect of different wiper tool edge geometries during the hard turning of AISI 4340 steel Langlang Jiang, Dazhong Wang
T
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Shanghai University of Engineering Science, Shanghai 201620, China
ARTICLE INFO
ABSTRACT
Keywords: Wiper tool Tool edge geometry Finite element method (FEM) Cutting force
This paper investigates the performance of different wiper tool edge geometries in machining of AISI 4340 steel using finite element method (FEM) simulation. The cutting process is simulated with Arbitrary Lagrangian–Eulerian (ALE) approach in AdvantEdge. The purpose is to explore the effects of wiper tool geometries on cutting performance of AISI 4340 steel compare with conventional tool. We explored the cutting force, residual stress, Mises stress and distribution of temperature, and the chip shape also be examined. The simulation results suggest that wiper tools can increase cutting force and peak cutting temperature compare with experimental result, but it can reduce the temperature of distribution in the cutting edge which is beneficial to reduce the wear of tool. At the same time, the wiper tools also have a great influence on chip shape and stress.
1. Introduction Hard turning (HT) is a major metal cutting process for reducing the workpiece diameter to the specified size and producing smooth surface finish on workpiece materials with hardness greater than 48 HRC without grinding. With the development of machining technology, hard turning instead of grinding has achieved obvious economic benefits. The popularity of hard turning is mainly due to its ability to generate complex geometric surfaces with better shape accuracy and better tolerances in one process [1]. It is widely used in the processing of AISI 4340 because of its characteristics of high processing efficiency, clean processing technology, less investment in equipment and high overall processing precision. The hard turning process of alloy steel requires greater cutting force and cutting temperature than the process of normal steel. Therefore, it is necessary to do more research on hard turning in order to meet the rapid development of production requirements. In recent years, the wiper tool has been widely used in hard turning. The wiper edge is the transition between the primary and secondary cutting edges and is actually the extreme form of the secondary cutting edge. It mainly serves to increase the impact resistance of the tool tip and reduce the surface roughness value of the workpiece. Rocha et al. [2] optimized the turning process of AISI H13 hardened steel by using PcBN wiper tool and obtained optimal turning process conditions. Kumar et al. [3] presented a study of such research contributions, mechanics of material removal, finite element analyses, associated challenges and possible remedies related to hard turning with wiper geometry tool. Addona et al. [4] made a comparison of turning operation using conventional turning tool, wiper inserted geometry tool and grinding process on the basis of surface roughness. The results indicate that feed rate has significant role to play in producing lower surface roughness followed by cutting speed. Grzesik and Wanat [5] presented a comparative study on surface finish generated in a hard turning using conventional and wiper ceramic inserts. According to
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Corresponding author. E-mail address: [email protected] (D. Wang).
https://doi.org/10.1016/j.simpat.2019.03.006 Received 24 October 2018; Received in revised form 27 February 2019; Accepted 18 March 2019 Available online 19 March 2019 1569-190X/ © 2019 Published by Elsevier B.V.
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these authors, keeping equivalent feed rates, 0.1 mm/rev for conventional and 0.2 mm/rev for wiper inserts. O¨ zel et al. [6] indicate that the smaller average surface roughness (Ra) is attainable with wiper tools. Davim et al. [7] evaluated machinability turning AISI D2 hardened steel with ceramic tools using statistical techniques, and their tests show that with the appropriated choice of cutting parameters it is possible to obtain a surface roughness (Ra < 0.8 mm) that allows cylindrical grinding operations to be eliminated. Guddat et al. [8] made a analysis of surface integrity in hard turning using wiper inserts compared with conventional inserts. They found that the application of PCBN wiper inserts leads to reduce surface roughness and higher compressive residual stresses. Aouici et al. [9] described a comparison of machining forces and flank wear between wiper ceramic (multi radii) and conventional ceramic cutting tools in dry hard turning of cold work tool steel AISI 4140 (60 Hardness Rockwell Cone (HRC)). It is revealed that the uncoated ceramics performs better than the coated ceramics with reference to machining forces. On the contrary, wiper ceramic cutting tools have the better performance compared with conventional ceramic cutting tools, in particular, the flank wear. Mun˜ ozSa´ nchez et al. [10] found that all types of wear lead to increased residual stress when compared with the reference geometry, being this one of the undesired effects of tool wear during machining operations. Mohammadpour et al. [11] found that with increasing cutting speed and feed rate the maximum value of tensile residual stresses were increased. Gaitonde et al. [12] studied the influence of cutting speed, feed rate, and machining time on machinability aspects such as specific cutting force, surface roughness, and tool wear in AISI D2 cold work tool steel hard turning with wiper tool, the results showed that the wiper ceramic inserts are desirable for achieving a better surface finish and lesser specific cutting force as compared with conventional insert. Suresh et al. [13] analyzed the influence of cutting speed, feed rate, depth of cut and machining time on machinability characteristics such as machining force, surface roughness and tool wear during turning of AISI 4340 high strength low alloy steel using coated carbide inserts. They inferred that tool wear can be minimized by employing lower values of cutting speed, feed rate, depth of cut and machining time. Liu et al. [14] studied the influence of tool edge and tool wear on the residual stress distribution of hard steel turning of bearing steel. The results obtained in this study show that the tool nose radius affects the residual stress distribution significantly. Capello et al. [15] established an empirical relationship between residual stress and process parameters. Navas et al. [16] studied the effect on the final surface stress state in AISI 4340 steel of cutting speed, feed, tool nose radius, geometry of the tool chip breaker and coating of the cutting tool. The wiper of length is 1.1–1.5 times of feed. Fig. 1 illustrates four major types of edge preparation design used in most commercial cutting inserts: conventional tool (sharp edge and hone edge), arc wiper and line wiper. Usually, the shape of the wiper blade is arc and line. Fig. 2 illustrates schematic diagram of the geometry of conventional tools and wiper tools: (a) Arc wiper tool The radius r of the tool tip is increased to improve the smoothness of the machined surface and the durability of the tool. However, it also increases the grinding force and is prone to vibration. For high speed grinding steel turning tools, r is 0.5–5 mm, for carbide turning tools, r is 0.5–2 mm. When fine turning, r takes a small value, and when rough turning, it takes a large value. For general ordinary lathes, the value does not exceed 2 mm. It can be seen from Fig. 2 that the common blade and the wiper blade of the same basic size have the following dimensional relationships: (1)
= Kr x = (r2
r1)(1
cos ) = (r2
r1)(1
(2)
cosKr )
where r1 is tool nose radius, r2 is wiper blade connects the large arc radius of the tool tip and the secondary cutting edge, O1 is center of the arc of the tool tip, O2 is center of large arc, Kr′ is secondary declination of the tool. (b) Line wiper tool When the arc transition edge is not easy to grind or symmetrical, a straight line wiper can be used. When the length of the wiper is 0.5–2 mm, the off angle is usually about half of the lead angle. It can be seen from Fig. 2 that the common blade and the wiper blade of the same basic size have the following dimensional relationships:
Fig. 1. Wiper tool of edge shape. 251
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Fig. 2. Schematic diagram of the geometry of conventional hone edge tools and wiper tools (a) Line wiper tool and (b) Arc wiper tool.
bs = (r1
r2)tanKr +
(r2
r1)(1 cosKr + x cosKr ) sinKr cos Kr
(3)
the tool nose angle is θ, the relationship between Δr and Δx is as follows: (4)
x = rsin( /2) 2. Numerical simulation 2.1. Numerical approach and boundary conditions
Numerical simulation of the cutting process can provide detailed results for process variables, such as stress, strain, strain rate and temperature which are extremely difficult to measure with current technology. The undeformed mesh geometry in the case of new tool, presenting the main characteristics of the model is shown in Fig. 3 developed by Mun¨ oz-Sa´ nchez et al. [10]. Regions 1–3 combine sliding and Lagrangian/Eulerian boundaries and region 4 Eulerian. The tool was fixed and the cutting speed was applied to the workpiece. Cutting force took place in the plane 1–2 under plane strain conditions. Continuous chip formation was assumed. The depth of the workpiece was selected taking into account the typical profile of machined induced residual stresses. On the other hand, it is important to note that the dimensions of the undeformed chip (curvature radius and width) are not critical, thus, changes in these magnitudes can lead to successful calculations with the model. The metal cutting process can be regarded as a two-dimensional orthogonal cutting model when simulating the cutting process by using the FEM. the rake angle is 10∘ and the clearance angle is 6∘. The material employed in this work is AISI 4340 steel in normalized state. The chemical composition of this steel measured by X-ray fluorescence (XRF) analysis is gathered in Table 1. The mechanical properties for AISI-4340 steel are given in Table 2.
Fig. 3. Implementation of boundary condition and type of contour in the model. 252
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Table 1 The main chemical composition of AISI4340 steel [16]. C
Mn
P
S
Si
Cr
Mo
Ni
0.425
0.81
0.015
0.0058
0.31
0.83
0.25
1.80
Table 2 Material properties for the workpiece and tool [17]. Material properties
Workpiece
Tool
Material Young’s modulus (GPa) Hardness (HRC) Density (Kg m3) Poisson’s ratio
AISI 4340 208 48 7830 0.3 44.5
CBN 587
Thermal Conductivity (W m Specific heat (J kg
1∘C 1)
1 ∘C 1 )
Thermal expansion coefficient(∘C
0.13 44
477
1)
1.23 × 10
750
4.7 × 10
6
6
The AdvanteEdge is used for display dynamics analysis. In order to better reflect the hard-cutting process, the workpiece size is 5 mm × 2 mm in the cutting simulation model. The cutting edge radius of the tool is 4 µm, the rake angle is 10∘, the back angle is 6∘, the cutting speed is 100 mm/s, and the workpiece material is the ductile material AISI 4340. The material has been studied in depth and the simulation provides reliable calculation parameters. In this paper, Johnson–Cook model is employed to describe material model. The mechanical properties and Johnson–Cook parameters for AISI-4340 steel are given in Table 3 and the normal form which can be found below [18]. The model is suitable for describing the viscoplasticity of materials with temperature and the hardening characteristics of materials under large strain rates. It is very suitable as a constitutive model for cutting materials. The relationship is as follows:
= A + B ¯ pn
T* =
T Tm
1 + Cln
¯e p ¯0
1
T *m
(5)
Tr Tr
(6)
where A is the yield strength, B is the hardening modulus, C is the sensitivity coefficient of the material to the equivalent plastic strain rate, m is the softening coefficient affected by temperature, n is the hardening coefficient, ¯0 is the reference strain rate, Tm is the melting point, Tr is the conversion temperature which equals to room temperature. A, B, C, n and m are material constants. 2.2. The force and stress model The cutting force has an important influence on the cutting process, which directly affects the cutting temperature. It also leads to faster tool wear which affects the quality of the machined surface, and even causes deformation and vibration of the workpiece and the tool. At the same time, the cutting force is also the main basis for the energy consumption of the computer bed. It has great significance on the design and production of machine tools, fixtures and tools. Chou et al. [19] investigated the effect of tool nose radius on finish turning of hardened AISI 52,100 steels. Surface finish, tool wear, cutting forces, and, particularly, white layer (phase transformation structures) were evaluated at different machining conditions. Results show that large tool nose radius only give finer surface finish, but comparable tool wear compared to small nose radius tools. Specific cutting energy slightly increases with tool nose radius. The two-dimensional orthogonal model facilitates finite element numerical simulation analysis, which helps people to understand the internal mechanism of metal cutting. It is a powerful tool for studying chip shape, cutting heat, residual stress, tool wear and process parameter optimization. It can be seen from Fig. 4. In the rake face, where Fn is normal force, Ff is friction force, Fr is the joint force. In the shear plane, where Fns is positive pressure, Fs is shear force, Fr′ is the joint force. AD represents the sectional area of the cutting layer, As represents the sectional area of the shearing surface, and τ represents the shear stress on the shearing surface. Fp and Fc represent the cutting fore component. The relationship of each parameter is as follows: Table 3 Johnson–Cook model parameters for workpiece material AISI 4340. A/MPa
B/MPa
C
m
n
Tm/K
Tr/∘C
792
510
0.014
1.03
0.26
1793
20
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Fig. 4. The balanced system of cutting force.
AD = hD bD As = AD /sin Fr = Fs /cos( + Fc = Fr cos( ) Fp = Fr sin( )
(7)
)
Fs /cos( + ) = AD /sin cos( + ) Fr cos( ) = AD cos( )/sin cos( + ) = AD sin( )/sin cos( + Fr sin(
(8)
) )
(9)
Surface roughness is an important machining performance measure, especially in finish hard turning operation. Venkatasubbaiah Kambagowni et al. [20] discusses the impact of workpiece hardness, feed and depth of cut on Arithmetic mean roughness (Ra), root mean square roughness (Rq), mean depth of roughness (Rz) and total roughness (Rt) during the hard turning. Matsumoto et al. [21] made a effect of hardness on the surface roughness of AISI4340 was studied. The results show that hardness is an important factor affecting the surface roughness of the machined surface. Esteves Correia and Paulo Davim et al. [22] considered the influence of the wiper inserts when compared with conventional inserts on the surface roughness obtained in turning. The results show finish machining with wiper inserts provide a similar roughness when compared with machining with a low feed rate using conventional inserts. The well-known ideal surface roughness equation, which represents the best possible finish that may be obtained for a given tool shape and feed is given by the following geometric expression:
Ra =
fn 2
(10)
8re
where f represent feed andre represent tool nose radius. As is shown above, it can be known that reducing the feed rate or increasing the radius of the tool tip can reduce the surface roughness value, but reducing the feed rate will reduce the production efficiency, and increasing the tool nose radius will increase the cutting force. The large feed rate will reduce the surface roughness, so the design of the smoothing edge structure can be used to reduce the surface roughness. The shape of the wiper blade includes a circular arc shape, a linear shape, a straight line and a circular arc shape, and the principle is to reduce the surface roughness with a very small Kr′ value. 3. Experimental work In this work, a bar made of AISI 4340 mould steel was turned in orthogonal mode on a CA6140 processing lathe, and the cutting force was measured in each case. Fig. 5 shows the cylindrical bar of 50 mm diameter and 700 mm length made of AISI 4340 alloy steel which is used for the experiment. In every set of tests, we use a grinding machine to polish the cutting edge of the CBN tool. Different wiper blades with lengths of lab and arc radius of rbc were used to process AISI 4340 steel. The primary rake angle of the tool was 10∘ in all cases. A chip load of 0.1 mm and a cutting speed of 100 m/min were adopted. More details of the experimental work can be found in Table 4. 254
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Fig. 5. Experiment equipment. Table 4 Tool edge geometry in cutting tests with carbide tools. Case
Nose radius(mm)
Cutting speed(v)m/min
Feed(rev/min)
Depth of cut(d)(mm)
lab
rcd
Sharp edge tool Conventional tool Arc wiper tool Line wiper tool
0 0.2 0.2 0.2
100 100 100 100
0.1 0.1 0.1 0.1
1 1 1 1
0 0 0 0.2
0 0 0.8 0
4. Results and discussion 4.1. Temperature distribution The cutting temperature problem is an important parameter for studying high-speed machining, which has a great influence on tool wear, tool life, surface quality, machining efficiency and part accuracy. Shihab et al. [23] investigated the effect of cutting parameters (cutting speed, feed rate and depth of cut) on the cutting temperature in hard turning of AISI 52,100 alloy steel. Cui et al. [24] found that feed rate and depth of cut had greater effects on the maximum value of heat flux in saw-tooth chip formation than they did on the minimum value. The peak machined surface temperature occurred along the intersection of cutting edge and the machined surface. Its magnitude was mainly determined by the shear plane heat source and further increased due to flank face frictional heat source [25]. As is shown in Fig. 6, wiper tools have great influence on temperature distribution, the line wiper tool and sharp edge tool produced approximate higher peak temperature and temperature regions in the first deformation zone. While the hone edge tool and arc wiper tool produced approximate lower peak temperature and temperature regions in the tip of tool. Fig. 7 (a) shows the temperature profiles of the rake face and the flank face during hard turning, the part of (1) is distribution of flank face and the part of (2) is the distribution of rake face. We can find that wiper tool can reduce the temperature of flank face compared with conventional tool, but wiper tool caused the temperature of the rake face to rise. This is because the wiper tool has a lager radius of the arc of the tool and increases the contact area between the chip and the tool, so large cutting force causes an increase in temperature. we can also draw similar conclusions in Fig. 7 (b). 4.2. Comparative analysis of force Cutting force refers to the cutting force that is equal in magnitude and opposite in direction acting on the workpiece and the tool during the cutting process. Generally speaking, during cutting, the workpiece material resists the resistance generated when the tool is cut. Bartarya et al. [26] observed that radial force seems to be dominant in hard turning which makes it different from the conventional machining but effective investigation about force and friction conditions are still to be taken up. We extracted the simulated data and the experimental data for comparison which can be seen Fig. 8. It is seen in the Fig. 8, the simulated cutting forces show good agreement with the measured data. We can find that the wiper tool has a certain influence on both main cutting force and thrust force, and arc wiper tool has a great influence on cutting force compare with line wiper tool. Both wiper tools increase the cutting force. The arc wiper tool increases by approximately 8% of the main cutting force compare with conventional hone edge tool and line wiper tool increases by approximately 4% of the main cutting force compare with conventional hone edge tool. The arc wiper tool increases by approximately 19% of the thrust force compare with conventional hone edge tool and line wiper tool reduces by approximately 16% of the thrust force compare with conventional hone edge tool. We can also get similar conclusions from [27] and [28]. The common conclusion they draw is that the wiper tool has a larger cutting force during machining compare with conventional tool.
255
Fig. 6. Temperature distribution of the (a) sharp edge tool (b) hone edge tool (c) arc wiper tool (d) line wiper tool during hard turning.
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256
Fig. 7. Temperature distribution of the (a) rake face and flank face (b) peak temperature during turning.
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Fig. 8. The effect of different tools on cutting force of (a) Main cutting force and (b) Thrust force.
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Fig. 9. Crimp degree of different chips produced by different tool.
L. Jiang and D. Wang
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Table 5 Crimp degree of different chips produced by different tool. Chip size
(a)Sharp edge tool
(b)Hone edge tool
(c)Arc wiper tool
(d)Line wiper tool
H L H/L
0.91 0.60 1.516
0.54 0.79 0.683
O.53 0.64 0.843
0.64 0.80 0.80
4.3. Effect on the chip shape The chip formation process is of great significance for ensuring processing quality, reducing manufacturing costs and increasing productivity. Because various physical phenomena during cutting, such as cutting forces, cutting heat, tool wear and machining quality, are based on the chip formation process. Zhu et al. [29] presented an experimental study on the 3D chip morphology properties during orthogonal turn-milling of Al6061-T6 and discussed the effects of cutting parameters on turn-milling chip length and thickness. We describe the effect of the wiper by analyzing the degree of curling of the chips after cutting. We define a method for measuring the degree of chip curl. The distance between the tangent of the highest point of the chip curl and the unprocessed surface is H, and the distance between the tangent of the widest point of the chip curl and tangent point (chip and the tool) is L. The degree of curl of the chip is judged according to the distance H and L. The smaller the H and L, the greater the degree of curling of the chips, conversely, the smaller the degree of curling. In Fig. 9, we can find that the wiper has a significant effect on changing the chip shape. Grzesik [30] explored the wear development on wiper Al2O3–TiC mixed ceramic tools in hard machining of high strength steel. It found that wear of tool flank faces are mainly concentrated on the tool corner and the active secondary cutting (trailing) edge. So the study of chip shape is good for us to better understand the wear of the tool. The chip produced by arc wiper tool with a large degree of curl, and the curl radius is small and the chip is separated from the tool rake face early, which reduces the chip contact area. The friction reducing effect is obvious, which increases the heat convection of the air and the tool and reduce the cutting temperature. Both Fig. 9 and Table 5 show arc wiper tool produces chips with a high degree of curling. We can also get similar conclusions from Fig. 7. 4.4. Stress analysis On the machined surface, the tensile residual stresses decrease with an increase the edge radius and increase with an increase the cutting speed. However, below the surface, the compressive residual stresses increase with an increase the depth of cut. The stresses could directly affect fatigue life, corrosion resistance and component distortion. Therefore, it is necessary to analyze the stress distribution after machining the workpiece. It can be seen in Fig. 10, we can find that Mises stress is mainly concentrated at the tip position and the first deformation zone. Fig. 11 shows the effect of different tool edge shape on Mises stress and residual stress. As is shown Fig. 11(a), we explored the effect of the wiper tool on alloy steel AISI 4340 about Mises stress. We can find that wiper tools have little influence on Mises stress compare with conventional hone edge tools, but compared to sharp edge tools, the wiper tools can greatly reduce Mises stress. It can be seen in the Fig. 11 (b), the wiper tool produces a high residual stress near the machined surface. We can also get similar conclusions from [8], they found that the application of PCBN wiper inserts leads to reduce surface roughness and higher compressive residual stress. 5. Conclusions This paper uses the finite element method to simulate the orthogonal cutting process of AISI 4340 steel with several different wiper edges, and the cutting temperature, machining force, chip shape and stress during the machining process are compared. The following conclusions can be derived: (a) The wiper tool can reduce the temperature of flank face compared with conventional tool, but wiper tool caused the temperature of the rake face to rise. This is because the wiper tool has a lager radius of the arc of the tool and increases the contact area between the chip and the tool, so large cutting force causes an increase in temperature. Compared to conventional hone edge tool, the arc wiper tools increase the cutting temperature by 4% and the line wiper tool increase cutting temperature by 8%. (b) Both wiper tools can increase the cutting force. The arc wiper tool increases by approximately 8% of the main cutting force compare with conventional hone edge tool and line wiper tool increases by approximately 4% of the main cutting force compare with conventional hone edge tool. The arc wiper tool increases by approximately 19% of the thrust force compare with conventional hone edge tool and line wiper tool reduces by approximately 16% of the thrust force compare with conventional hone edge tool. (c) The wiper tools have a great influence on the degree of curling of the chip. The arc wiper blade forms a chip with a large degree of curling, which makes the chip and the rake face separate earlier, which is beneficial to reduce the wear of the rake face. (d) Wiper tools also have influence on Mises stress and residual stress. We can find that the wiper tool can increase the Mises stress by about 43% compare with conventional hone edge tool, and can significantly reduce Mises stress compare with sharp edge tool. The wiper tool produces a high residual stress near the machined surface. 260
Fig. 10. Stress distributions for(a) Sharp edge tool (b) Conventional hone edge tool (c) Arc wiper tool and (d) Line wiper tool.
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Fig. 11. Comparison of different tool edge shape of (a) Mises stress and (b) Residual stress after turning.
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References [1] J. Kundrák, B. Karpuschewski, K. Gyani, V. Bana, A.O.H. turning, J. Mater. Process. Technol. 202 (2008) 328–338. [2] L.C.S. Rocha, A.P. de Paiva, P.R. Junior, P.P. Balestrassi, P.H.d.S. Campos, Robust multiple criteria decision making applied to optimization of AISI h13 hardened steel turning with PCBN wiper tool, Int. J. Adv. Manuf. Technol. 89 (2016) 2251–2268. [3] A. Kumar, S.K. Pradhan, Investigations into hard turning process using wiper tool inserts, Mater. Today 5 (2018) 12579–12587. [4] D.M. DAddona, S.J. Raykar, Analysis of surface roughness in hard turning using wiper insert geometry, Procedia CIRP 41 (2016) 841–846. [5] W. Grzesik, T. Wanat, Surface finish generated in hard turning of quenched alloy steel parts using conventional and wiper ceramic inserts, Int. J. Mach. Tools Manuf. 46 (15) (2006) 1988C1995. [6] T. özel, Y. Karpat, L. Figueira, J.P. Davim, Modelling of surface finish and tool flank wear in turning of AISI d2 steel with ceramic wiper inserts, J. Mater. Process. Technol. 189 (2007) 192C198. [7] J.P. Davim, L. Figueira, Machinability evaluation in hard turning of cold work tool steel (d2) with ceramic tools using statistical techniques, Mater. Des. 28 (2007) 1186C1191. [8] J. Guddat, R. M’Saoubi, P. Alm, D. Meyer, Hard turning of AISI 52100 using PCBN wiper geometry inserts and the resulting surface integrity, Procedia Eng. 19 (2011) 118–124. [9] H. Aouici, M. Elbah, M.A. Yallese, B. Fnides, I. Meddour, S. Benlahmidi, Performance comparison of wiper and conventional ceramic inserts in hard turning of AISI 4140 steel: analysis of machining forces and flank wear, Int. J. Adv. Manuf. Technol. 87 (2016) 2221–2244. [10] A.M. noz Sánchez, J.A. Canteli, J.L. Cantero, M.H. Migulez, Numerical analysis of the tool wear effect in the machining induced residual stresses, Simul. Model. Pract. Theory 19 (2011) 872–886, https://doi.org/10.1016/j.simpat.2010.11.011. [11] M. Mohammadpour, M.R. Razfar, R.J. Saffar, Numerical investigating the effect of machining parameters on residual stresses in orthogonal cutting, Simul. Model. Pract. Theory 18 (2010) 378–389, https://doi.org/10.1016/j.simpat.2009.12.004. [12] V.N. Gaitonde, S.R. Karnik, L. Figueira, J.P. Davim, Performance comparison of conventional and wiper ceramic inserts in hard turning through artificial neural network modeling, Int. J. Adv. Manuf. Technol. 52 (2010) 101–114. [13] R. Suresh, S. Basavarajappa, V.N. Gaitonde, G.L. Samuel, Machinability investigations on hardened AISI 4340 steel using coated carbide insert, Int. J. Refract. Met. Hard Mater. 33 (2012) 75–86. [14] M. Liu, J.I. Takagi, A. Tsukuda, Effect of tool nose radius and tool wear on residual stress distribution in hard turning of bearing steel, J. Mater. Process. Technol. 150 (2004) 234–241. [15] E. Capello, Residual stresses in turning: part i: influence of process parameters, J. Mater. Process. Technol. 160 (2005) 221–228. [16] V.G. Navas, O. Gonzalo, I. Bengoetxea, Effect of cutting parameters in the surface residual stresses generated by turning in AISI 4340 steel, Int. J. Mach. Tools Manuf. 61 (2012) 48–57. [17] S. Agrawal, S.S. Joshi, Analytical modelling of residual stresses in orthogonal machining of AISI4340 steel, J. Manuf. Processes 15 (2013) 167–179. [18] D.I. Lalwani, N.K. Mehta, P.K. Jain, Extension of oxley’s predictive machining theory for johnson and cook flow stress model, J. Mater. Process. Technol. 209 (2009) 5305–5312. [19] Y.K. Chou, H. Song, Tool nose radius effects on finish hard turning, Journal of Materials Processing Tech 148 (2004) 259–268. [20] V. Kambagowni, R. Chitla, S. Challa, Determining the effect of material hardness during the hard turning of AISI4340 steel, J. Inst. Eng.India (2018). [21] Y. Matsumoto, Effect of hardness on the surface integrity of AISI 4340 steel, Trans. ASME J. Eng. Ind. 108 (1986) 169–175. [22] A.E. Correia, J.P. Davim, Surface roughness measurement in turning carbon steel AISI 1045 using wiper inserts, Measurement 44 (2011) 1000–1005. [23] S.K. Shihab, Z.A. Khan, A. Mohammad, A.N. Siddiqueed, RSM Based study of cutting temperature during hard turning with multilayer coated carbide insert, Procedia Mater. Sci. 6 (2014) 1233–1242. [24] X. Cui, J. Guo, Effects of cutting parameters on tool temperatures in intermittent turning with the formation of serrated chip considered, Appl. Therm. Eng. 110 (2017) 1220–1229. [25] L. Chen, B.L. Tai, R.G. Chaudhari, X. Song, A.J. Shih, Machined surface temperature in hard turning, Int. J. Mach. Tools Manuf. 121 (2017) 10–21. [26] G. Bartarya, S.K. Choudhury, State of the art in hard turning, Int. J. Mach. Tools Manuf. 53 (2012) 1–14. [27] J.P. Davim, L. Figueira, Comparative evaluation of conventional and wiper ceramic tools on cutting forces, surface roughness and tool wear in hard turning AISI d2 steel, J. Eng. Manuf. 221 (4) (2007) 625C633. [28] V.N. Gaitonde, S.R. Karnik, L. Figueira, J. Paulo, Davim, machinability investigations in hard turning of AISI d2 cold work tool steel with conventional and wiper ceramic inserts, Int. J. Refract. Met. Hard Mater. 27 (2009) 754–763. [29] L. Zhu, X. Jin, C. Liu, Experimental investigation on 3d chip morphology properties of rotary surface during orthogonal turn-milling of aluminum alloy, Int. J. Adv. Manuf. Technol. (2015), https://doi.org/10.1007/s00170-015-7758-y. [30] W. Grzesik, Wear development on wiper Al2O3CTic mixed ceramic tools in hard machining of high strength steel, Wear 266 (2009) 1021–1028, https://doi.org/ 10.1016/j.wear.2009.02.010.
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