Thermoviscoplastic modelling of drilling: Twist drills

2008 ◽  
Vol 222 (3) ◽  
pp. 403-411 ◽  
Author(s):  
A Nayebi ◽  
H Vaghefpour
Keyword(s):  
Cutting Forces ◽  
Material Flow ◽  
Thrust Force ◽  
Orthogonal Cutting ◽  
Material Model ◽  
Thermomechanical Properties ◽  
Twist Drill ◽  
Viscoplastic Material ◽  
Al 7075 ◽  
Twist Drills

In this paper, a viscoplastic material model is proposed for drilling of metals. An analytical model is developed for predicting thrust force and torque in drilling with a twist drill. The thermomechanical properties are taken into consideration to describe the material flow in the primary shear zone and at the element—chip interface. The Johnson—Cook model is used. A temperature friction law is introduced. The approach is based on representing the cutting forces along the cutting lips as a series of oblique elements. Similarly, cutting in the chisel region is treated as orthogonal cutting with different speeds depending on the radial location. The section forces obtained by the model are combined to determine the overall thrust force and drilling torque. The results of the model are compared with the experimental results obtained by Bagci and Ozcelik in 2006 on Al 7075-T651.

Drilling Thrust and Torque Prediction of Viscoplastic Materials

2006 ◽  
Author(s):  
Hossein Vaghefpour ◽  
Ali Nayebi
Keyword(s):  
Shear Zone ◽  
Cutting Forces ◽  
Material Flow ◽  
Thrust Force ◽  
Orthogonal Cutting ◽  
Thermomechanical Properties ◽  
Twist Drill ◽  
Proposed Model ◽  
Thrust And Torque ◽  
Good Agreement

A model for drilling of viscoplastic materials is presented. An analytical model is developed for predicting thrust force and torque in the drilling with a twist drill. The thermomechanical properties are accounted for describing the material flow in the primary shear zone and at the element-chip interface. A temperature friction law is introduced. The approach is based on the representing the cutting forces along the cutting lips as a series of oblique elements. Similarly, cutting in the chisel region is treated as orthogonal cutting with different speeds depending on the radial location. The section forces obtained by the model are combined to determine the overall thrust force and drilling torque. The results of the proposed model are compared with experimental results and a good agreement is obtained.

A Study on the Influence of Laser Parameters on Laser-Assisted Machining of AISI H-13 Steel

2019 ◽  
Vol 827 ◽  
pp. 92-97 ◽  
Author(s):  
Evaggelos Kaselouris ◽  
A. Baroutsos ◽  
T. Papadoulis ◽  
Nektarios A. Papadogiannis ◽  
Michael Tatarakis ◽  
...  
Keyword(s):  
Laser Beam ◽  
Cutting Forces ◽  
Local Heating ◽  
Orthogonal Cutting ◽  
Material Model ◽  
Beam Diameter ◽  
Laser Parameters ◽  
Laser Assisted Machining ◽  
Von Mises ◽  
Cutting Processes

The machinability of a steel workpiece through conventional and Laser-Assisted Machining (LAM) is studied by the help of the Finite Element Method (FEM). In LAM, the laser beam is applied as a heat source to ensure sufficient local heating of the workpiece at a certain distance from the cutting tool and the machinability of materials is increased since the values of the cutting forces are decreased. A thermostructural FEM model is developed to simulate the conventional and the LAM orthogonal cutting of AISI H-13 steel. The Johnson-Cook material model that takes into account the effect of plastic strain, strain rate and temperature, along with a fracture model, is used in the simulations. For varying feed rate, parametric simulations are carried out, for different test cases of the laser beam diameter and the laser heat flux. Key engineering parameters, like cutting forces, temperature distributions, Von Mises stresses and plastic strains, are compared for both cutting processes. This comparison leads to important notifications on the influence of the cutting and laser parameters to LAM. The obtained results indicate that LAM may improve the machinability of AISI H-13 steel by reducing the cutting forces to a maximum percentage of ~15%.

A Methodology to Determine Work Material Flow Stress and Tool-Chip Interfacial Friction Properties by Using Analysis of Machining

2004 ◽  
Author(s):  
Tug˘rul O¨zel ◽  
Erol Zeren
Keyword(s):  
Flow Stress ◽  
Material Flow ◽  
Orthogonal Cutting ◽  
Material Model ◽  
Interfacial Friction ◽  
Frictional Stress ◽  
Rake Face ◽  
Friction Characteristics ◽  
Work Material ◽  
1045 Steel

In this paper, we develop a methodology to determine flow stress at the machining regimes and friction characteristics at the tool-chip interface from the results of orthogonal cutting tests. We utilize metal cutting analysis originally developed by late Oxley and present some improvements. We also evaluate several temperature models in calculating the average temperatures at primary and secondary deformation zones and present comparisons with the experimental data obtained for AISI 1045 steel through assessment of machining models (AMM) activity. The proposed methodology utilizes measured forces and chip thickness obtained through a basic orthogonal cutting test. We conveniently determine work material flow stress at the primary deformation zone and the interfacial friction characteristics along tool rake face. Calculated friction characteristics include parameters of the normal and frictional stress distributions on the rake face. Determined flow stress data from orthogonal cutting tests is combined with the flow stress measured through split-hopkinson pressure bar (SHPB) tests and the Johnson-Cook work material model is obtained. Therefore, with this methodology, we extend the applicability of Johnson-Cook work material model to machining regimes.

A Methodology to Determine Work Material Flow Stress and Tool-Chip Interfacial Friction Properties by Using Analysis of Machining

2005 ◽  
Vol 128 (1) ◽  
pp. 119-129 ◽  
Author(s):  
Tuğrul Özel ◽  
Erol Zeren
Keyword(s):  
Flow Stress ◽  
Normal Stress ◽  
Material Flow ◽  
Orthogonal Cutting ◽  
Material Model ◽  
Interfacial Friction ◽  
Rake Face ◽  
Friction Characteristics ◽  
Work Material ◽  
1045 Steel

In this paper, we develop a methodology to determine flow stress at the machining regimes and friction characteristics at the tool-chip interface from the results of orthogonal cutting tests. We utilize metal cutting analysis originally developed by late Oxley and present some improvements. We also evaluate several temperature models in calculating the average temperatures at primary and secondary deformation zones and present comparisons with the experimental data obtained for AISI 1045 steel through assessment of machining models (AMM) activity. The proposed methodology utilizes measured forces and chip thickness obtained through a basic orthogonal cutting test. We conveniently determine work material flow stress at the primary deformation zone and the interfacial friction characteristics along the tool rake face. Calculated friction characteristics include parameters of the normal and frictional stress distributions on the rake face that are maximum normal stress σNmax, power exponent for the normal stress distribution, a, length of the plastic contact, lp, length of the tool-chip contact, lc, the average shear flow stress at tool-chip interface, kchip, and an average coefficient of friction, μe, in the sliding region of the tool-chip interface. Determined flow stress data from orthogonal cutting tests is combined with the flow stress measured through split-hopkinson pressure bar (SHPB) tests and the Johnson-Cook work material model is obtained. Therefore, with this methodology, we extend the applicability of a Johnson-Cook work material model to machining regimes.

Effect of Cutting Parameters on Tool Life: Case Study Twist Drill

2015 ◽  
Vol 1101 ◽  
pp. 397-401
Author(s):  
Hossein Vaghefpour ◽  
Ali Dahar ◽  
Kobra Zabeh
Keyword(s):  
Temperature Distribution ◽  
Cutting Forces ◽  
Flow Direction ◽  
Orthogonal Cutting ◽  
Viscoelastic Model ◽  
Cutting Speed ◽  
Contact Length ◽  
Friction Law ◽  
Chip Flow ◽  
Twist Drills

<p>This study discusses the relationship between various parameters of drilling and cutting tools using an analytical model is developed for predicting life and wear of twist drills by a temperature dependent friction law. The model permits the continuous determination of the cutting forces along the cutting lips and chisel edge which can be combined with the dynamics forces of the initial penetration and the chip evacuation forces in drilling .The approach is based on representing the cutting forces along the cutting lips as a series of oblique elements. Similarly, cutting in the chisel region is treated as orthogonal cutting with different speeds depending on the radial location. The chip flow is determined by the assumption that the friction force on the tool face is collinear to the chip flow direction. The contact length between the chip and the tool and the temperature distribution at the tool–chip interface which has an important effect on the tool wear were predicted. The model permits to predict the chip flow direction, the contact length between the chip and the tool and the temperature distribution at the tool–chip interface. Using the thermo-viscoelastic model and the temperature friction law, the tangential forces, friction coefficient and contact length on the cutting element as a function of radius, for different feed rate and cutting speed, are obtained. The proposed model results are compared with experimental results and good agreement is obtained.</p>

RESEARCH ON CUTTING FORCES AND CUTTING TEMPERATURE IN ORTHOGONAL CUTTING SOFTWOOD AND HARDWOOD PARALLEL TO GRAIN

2018 ◽  
Vol 50 (4) ◽  
pp. 458-464
Author(s):  
Xu Bao ◽  
Xiaolei Guo ◽  
Pingxiang Cao ◽  
Linlin Xie ◽  
Minsi Deng
Keyword(s):  
Cutting Forces ◽  
Orthogonal Cutting ◽  
Cutting Temperature

scholarly journals Effect of Twist Drill Geometry and Drilling Parameters on Hole Quality in Single-Shot Drilling of CFRP/Al7075-T6 Composite Stack

2021 ◽  
Vol 5 (7) ◽  
pp. 189
Author(s):  
Muhammad Hafiz Hassan ◽  
Jamaluddin Abdullah ◽  
Gérald Franz ◽  
Chim Yi Shen ◽  
Reza Mahmoodian
Keyword(s):  
Feed Rate ◽  
Thrust Force ◽  
Critical Dimension ◽  
Helix Angle ◽  
Single Shot ◽  
Twist Drill ◽  
Hole Quality ◽  
Drilling Parameters ◽  
Industry Practice ◽  
Maximum Thrust

Drilling two different materials in a layer, or stack-up, is being practiced widely in the aerospace industry to minimize critical dimension mismatch and error in the subsequent assembly process, but the compatibility of the drill to compensate the widely differing properties of composite is still a major challenge to the industry. In this paper, the effect of customized twist drill geometry and drilling parameters are being investigated based on the thrust force signature generated during the drilling of CFRP/Al7075-T6. Based on ANOVA, it is found that the maximum thrust force for both CFRP and Al7075-T6 are highly dependent on the feed rate. Through the analysis of maximum thrust force, supported by hole diameter error, hole surface roughness, and chip formation, it is found that the optimum tool parameters selection includes a helix angle of 30°, primary clearance angle of 6°, point angle of 130°, chisel edge angle of 30°, speed of 2600 rev/min and feed rate of 0.05 mm/rev. The optimum parameters obtained in this study are benchmarked against existing industry practice of the capability to produce higher hole quality and efficiency, which is set at 2600 rev/min for speed and 0.1 mm/rev for feed rate.

scholarly journals Modelling Texturised Cast Structures in the Forging of Superalloys

2011 ◽  
Vol 278 ◽  
pp. 210-215
Author(s):  
Jan Terhaar ◽  
Nikolaus Blaes ◽  
Dieter Bokelmann ◽  
Hendrik Schafstall
Keyword(s):  
Flow Stress ◽  
Material Flow ◽  
Cylindrical Specimen ◽  
Material Model ◽  
Growth Direction ◽  
Solidification Structure ◽  
Vacuum Arc ◽  
Correct Prediction ◽  
Dendrites Growth ◽  
Stress Dependency

The main objective of remelting processes commonly used in the production of super¬alloys is to obtain a columnar dendritic solidification structure throughout the whole ingot. Besides reduced microsegregation, this cast structure features a preferred orientation, which is depending on the primary dendrites’ growth direction and therefore closely related to the ingot’s pool shape. As a result, non-isotropic material behaviour can be observed during initial forging operations. Since the correct prediction of material flow is a prerequisite for the further analysis of forging processes by means of numerical simulation, the solidification texture’s influence on plastic flow was accounted for by the application of an anisotropic material model. The model according to Barlat was used to scale the flow stress with respect to the crystal orientations observed in the examination of vacuum arc remelted alloy 718, thereby considering the flow stress’ dependency on strain, strain rate and temperature. The parameters defining the material's anisotropy could be determined by the upsetting of cylindrical specimen from a remelted ingot.

Stresses in Ultrasonically Assisted Turning

2006 ◽  
Vol 5-6 ◽  
pp. 351-358 ◽  
Author(s):  
N. Ahmed ◽  
A.V. Mitrofanov ◽  
Vladimir I. Babitsky ◽  
Vadim V. Silberschmidt
Keyword(s):  
Ultrasonic Vibration ◽  
Vibration Frequency ◽  
Cutting Forces ◽  
Plastic Material ◽  
Process Zone ◽  
Three Dimensional ◽  
Rate Sensitivity ◽  
High Strength ◽  
Material Model ◽  
Shear Stresses

Ultrasonically assisted turning (UAT) is a novel material-processing technology, where high frequency vibration (frequency f ≈ 20kHz, amplitude a ≈15μm) is superimposed on the movement of the cutting tool. Advantages of UAT have been demonstrated for a broad spectrum of applications. Compared to conventional turning (CT), this technique allows significant improvements in processing intractable materials, such as high-strength aerospace alloys, composites and ceramics. Superimposed ultrasonic vibration yields a noticeable decrease in cutting forces, as well as a superior surface finish. A vibro-impact interaction between the tool and workpiece in UAT in the process of continuous chip formation leads to a dynamically changing stress distribution in the process zone as compared to the quasistatic one in CT. The paper presents a three-dimensional, fully thermomechanically coupled computational model of UAT incorporating a non-linear elasto-plastic material model with strain-rate sensitivity and contact interaction with friction at the chip–tool interface. 3D stress distributions in the cutting region are analysed for a representative cycle of ultrasonic vibration. The dependence of various process parameters, such as shear stresses and cutting forces on vibration frequency and amplitude is also studied.

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