Modelling Machining Dynamics Including Damping in the Tool-Workpiece Interface

1994 ◽  
Vol 116 (4) ◽  
pp. 435-439 ◽  
Author(s):  
M. A. Elbestawi ◽  
F. Ismail ◽  
R. Du ◽  
B. C. Ullagaddi
Keyword(s):  
Flank Wear ◽  
Wave Length ◽  
Phase Relationship ◽  
Machined Surface ◽  
Process Damping ◽  
Limits Of Stability ◽  
Machining Dynamics ◽  
Tool Vibrations ◽  
Simulation Results ◽  
Improved Model

Machining instability, namely chatter, occurs due to the interaction between the structural dynamics and the cutting process. The process damping generated at the tool-workpiece interface is an important parameter of that interaction. A significant enhancement to the chatter simulation model in milling is presented. It includes tracking of the interference between the tool flank and the generated wavy surface, which is the source of process damping. Results of simulation runs performed to determine the limits of stability are presented for sharp tools as well as for tools with various amount of flank wear. The phase relationship between the ploughing force and tool vibrations is explained using these simulations. It is also shown that the improved model accurately predicts the increase in the limit of stability due to tool wear, as well as the effect of the wave length of the machined surface undulations on process damping. Cutting tests of aluminum confirmed the simulation results.

Prediction of Coupled Torsional-Axial Vibrations of Drilling Tool With Clamping Boundary Conditions

2016 ◽  
Author(s):  
Xiaoliang Jin ◽  
Narahara Gopal Koya
Keyword(s):  
Coupling Model ◽  
Drilling Process ◽  
Hole Quality ◽  
Drilling Tool ◽  
Machining Dynamics ◽  
Receptance Coupling ◽  
Proposed Model ◽  
Tool Vibrations ◽  
Axial Vibrations ◽  
Simulation Results

Coupled torsional-axial vibrations of the drilling tool play a significant role in the machining dynamics of the drilling process. In this paper, the torsional-axial vibrations of the drilling tool due to the warping deformation of the pretwisted flute is modeled. An enhanced receptance coupling model is developed to predict the coupled torsional-axial vibrations of the drilling tool considering the dynamics of fixture and clamping conditions. Rigid and flexible receptance coupling methods are used, with the simulation results verified through modal experiments. The proposed model is able to provide optimum drilling tool configurations to avoid undesired tool vibrations and improve hole quality.

An improved model on forecasting temperature rise of high-speed angular contact ball bearings considering structural constraints

2018 ◽  
Vol 70 (1) ◽  
pp. 15-22 ◽  
Author(s):  
De-xing Zheng ◽  
Weifang Chen ◽  
Miaomiao Li
Keyword(s):  
Heat Generation ◽  
Temperature Rise ◽  
High Speed ◽  
Structural Constraints ◽  
Ball Bearings ◽  
Content Type ◽  
Grid Model ◽  
Simulation Results ◽  
Operation Parameters ◽  
Improved Model

Purpose Thermal performances are key factors impacting the operation of angular contact ball bearings. Heat generation and transfer about angular contact ball bearings, however, have not been addressed thoroughly. So far, most researchers only considered the convection effect between bearing housings and air, whereas the cooling/lubrication operation parameters and configuration effect were not taken into account when analyzing the thermal behaviors of bearings. This paper aims to analyze the structural constraints of high-speed spindle, structural features of bearing, heat conduction and convection to study the heat generation and transfer of high-speed angular contact ball bearings. Design/methodology/approach Based on the generalized Ohm’s law, the thermal grid model of angular contact ball bearing of high-speed spindle was first established. Next Gauss–Seidel method was used to solve the equations group by Matlab, and the nodes temperature was calculated. Finally, the bearing temperature rise was tested, and the comparative analysis was made with the simulation results. Findings The results indicate that the simulation results of bearing temperature rise for the proposed model are in better agreement with the test values. So, the thermal grid model established is verified. Originality/value This paper shows an improved model on forecasting temperature rise of high-speed angular contact ball bearings. In modeling, the cooling/lubrication operation parameters and structural constraints are integrated. As a result, the bearing temperature variation can be forecasted more accurately, which may be beneficial to improve bearing operating accuracy and bearing service life.

Research on chatter stability in milling and parameter optimization based on process damping

2017 ◽  
Vol 24 (12) ◽  
pp. 2642-2655 ◽  
Author(s):  
Lida Zhu ◽  
Baoguang Liu ◽  
Hongyu Chen
Keyword(s):  
Surface Roughness ◽  
Frequency Method ◽  
Processing Efficiency ◽  
Machined Surface ◽  
Process Damping ◽  
Analysis Methodology ◽  
Optimization Of Process Parameters ◽  
Orthogonal Experiments ◽  
Cutting Chatter ◽  
The Stability

Cutting stability is the prerequisite to ensure efficient and high-precision machining, resulting in poor surface quality and damaged tool, which is the basis for the optimization of process parameters and improvement of processing efficiency. Aiming at process damping caused by interference between a tool flank face and a machined surface of part, the dynamic model and critical condition of stability is proposed in the paper. The frequency method is applied to solve the stability of the cutting chatter, and the correctness of the model is validated by experiments. Moreover, through orthogonal experiments, regression analysis methodology are adopted to establish a prediction model of surface roughness and finally combined with the study findings on milling stability based on process damping and surface roughness, achieved optimization of the milling parameters by genetic optimization algorithm. This conclusion provides a theoretical foundation and reference for the milling mechanism research.

Identification of Process Damping Coefficient Based on Material Constitutive Property

2014 ◽  
Author(s):  
Xiaoliang Jin
Keyword(s):  
Energy Dissipation ◽  
Flank Wear ◽  
Orthogonal Cutting ◽  
Element Model ◽  
Machining Process ◽  
Damping Coefficient ◽  
Chatter Stability ◽  
Workpiece Material ◽  
Process Damping ◽  
Constitutive Property

The contact between the tool flank wear land and wavy surface of workpiece causes energy dissipation which influences the tool vibration and chatter stability during a dynamic machining process. The process damping coefficient is affected by cutting conditions and constitutive property of workpiece material. This paper presents a finite element model of dynamic orthogonal cutting process with tool round edge and flank wear land. The process damping coefficient is identified based on the energy dissipation principle. The simulated results are experimentally validated.

scholarly journals Dynamic Generation of Machined Surfaces, Part 2: Construction of Surface Topography

1991 ◽  
Vol 113 (2) ◽  
pp. 145-153 ◽  
Author(s):  
G. M. Zhang ◽  
S. G. Kapoor
Keyword(s):  
Surface Topography ◽  
Random Excitation ◽  
Surface Generation ◽  
Distribution Model ◽  
Excitation System ◽  
Machined Surface ◽  
Spiral Trajectory ◽  
Vibratory Motion ◽  
Texture Generation ◽  
Simulation Results

In Part 1 of these two-part papers, a normal distribution model has been formulated to describe the random excitation system present during machining. Part 2 presents a methodology to dynamically generate the surface topography under the random excitation environment through computer simulation. The proposed methodology uses the tool vibratory motion along with the tool geometrical motion to construct the topography of a machined surface. Both experimental and simulation results confirm that when a small feed is used, the influence of the spiral trajectory of tool geometrical motion on the surface generation decays dramatically and the random excitation system, on the opposite, is strengthened playing a significant role in surface texture generation.

An Approach to Improve Cutting Performance in Micromilling of Titanium Alloy

2020 ◽  
Vol 8 (2) ◽  
Author(s):  
Yunn-Shiuan Liao ◽  
Tsung-Hsien Li ◽  
Yi-Chen Liu
Keyword(s):  
Carbon Dioxide ◽  
Surface Roughness ◽  
Titanium Alloy ◽  
Flank Wear ◽  
End Milling ◽  
Cutting Speed ◽  
Liquid Carbon ◽  
Dry Cutting ◽  
Machined Surface ◽  
Liquid Carbon Dioxide

Abstract Application of liquid carbon dioxide to improve cutting performance in micro-end milling of Ti-6Al-4V titanium alloy was proposed in this study. It was found that the machined roughness decreased with the cutting speed as observed in the conventional cutting, when a 0.5 mm diameter end milling cutter was used in dry cutting. But, the tiny and shattered chips produced by the use of 0.3 mm diameter cutter could adhere on the machined surface and deteriorate surface finish, if the cutting speed was higher than 40 m/min. Cutting temperature was effectively decreased by applying liquid carbon dioxide during micromilling, which in turn reduced the amount of chips adhering on the machined surface and lowered flank wear. The surface roughness Ra at a cutting speed of 70 m/min was improved from 0.09 μm under dry cutting to 0.04 μm under the liquid carbon dioxide assisted cutting condition. And there were no flank wear and very few burrs left on the machined surface for the condition used in the experiment. The height of the burrs was only 25% of that under dry cutting. More, minimum quantity lubrication (MQL) was proposed to be applied together with the liquid carbon dioxide to enhance lubrication effect. It was noted that the machined surface roughness was further decreased by 15% as compared with that when the liquid carbon dioxide was applied alone. The height of burrs was reduced from 32 μm to 16 μm.

Correlation study of tool flank wear with machined surface texture in end milling

Measurement ◽  
2013 ◽  
Vol 46 (10) ◽  
pp. 4249-4260 ◽  
Author(s):  
S. Dutta ◽  
A. Kanwat ◽  
S.K. Pal ◽  
R. Sen
Keyword(s):  
Surface Texture ◽  
Flank Wear ◽  
End Milling ◽  
Correlation Study ◽  
Machined Surface ◽  
Tool Flank Wear

Performance Evaluation of TiAlN-PVD Coated Inserts for Machining Ti-6Al-4V under Different Cooling Strategies

2013 ◽  
Vol 685 ◽  
pp. 68-75 ◽  
Author(s):  
Salman Pervaiz ◽  
Ibrahim Deiab ◽  
Basil Darras ◽  
Amir Rashid ◽  
Mihai Nicolescu
Keyword(s):  
Flank Wear ◽  
Cutting Speed ◽  
Cutting Edge ◽  
Machined Surface ◽  
Cutting Inserts ◽  
Low Levels ◽  
Coated Carbide ◽  
Cutting Experiments ◽  
Cutting Speeds ◽  
Scanning Electron

Titanium alloys are labeled as difficult to materials because of their low machinability rating. This paper presents an experimental study of machining Ti-6Al-4V under turning operation. All machining tests were conducted under dry, mist and flood cooling approaches by using a TiAlN coated carbide cutting inserts. All cutting experiments were conducted using high and low levels of cutting speeds and feed rates. The study compared surface finish of machined surface and flank wear at cutting edge under dry, mist and flood cooling approaches. Scanning electron microscopy was utilized to investigate the flank wear at cutting edge under various cooling approaches and cutting conditions. Investigation revealed that TiAlN coated carbides performed comparatively better at higher cutting speed.

Diffusion Wear Mechanism of Single Crystal Diamond Tool in Machining Die Steels

2014 ◽  
Vol 625 ◽  
pp. 155-160
Author(s):  
Lai Zou ◽  
Ming Zhou
Keyword(s):  
Single Crystal ◽  
Wear Mechanism ◽  
Diamond Tool ◽  
Diamond Cutting ◽  
Machined Surface ◽  
Die Steels ◽  
Ferrous Metals ◽  
Diffusion Wear ◽  
Single Crystal Diamond ◽  
Simulation Results

Ultra-precision diamond cutting of ferrous metals has not been successful in application due to significant tool wear. In this work, numerical simulations and experimental investigations are presented in order to study the interface diffusion between diamond tool and workpiece materials. A diffusion model with respect to carbon atoms from diamond tool penetrating into chips and machined surface was established. The numerical simulation results of the diffusion process reveal that the distribution laws of carbon atoms concentration have a close relationship with diffusion distance, diffusion time and the original carbon concentration of the work material. In addition, diamond face cutting tests of die steels with different carbon content are conducted at different depth of cuts and feed rates to verify the previous simulation results. The wear morphology of rake face and flank face of diamond tool were detected by scanning electron microscopy. Energy dispersive X-ray analysis was proposed to investigate the change in chemical composition of the chips and machined surface. The results of this work benefit for a better understanding on the diffusion wear mechanism in single crystal diamond cutting of ferrous metals.

Comparison of Initial and Improved Hertz-Damp Model for Structural Pounding Simulation

2011 ◽  
Vol 243-249 ◽  
pp. 686-690 ◽  
Author(s):  
Yong Qiang Yang ◽  
Li Li Xie
Keyword(s):  
Contact Stiffness ◽  
Superposition Method ◽  
Restitution Coefficient ◽  
Initial Model ◽  
Collision System ◽  
Structural Pounding ◽  
Mode Superposition Method ◽  
Nonlinear Contact ◽  
Simulation Results ◽  
Improved Model

In order to compare the initial and improved Hertz-damp model, the dynamic equations of collision system were established based on Hertz-damp model and mode superposition method. Hertz-damp model can account for the influence of the nonlinear contact stiffness as well as the energy loss during structural pounding. The results analysis show that the initial model have the same simulation results with the improved model initial model when the restitution coefficient or the contact stiffness large enough. For typical concrete structural pounding, the initial model is available.

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