scholarly journals Estimates of the bistable region in metal cutting

2008 ◽  
Vol 464 (2100) ◽  
pp. 3255-3271 ◽  
Author(s):  
Zoltan Dombovari ◽  
R. Eddie Wilson ◽  
Gabor Stepan
Keyword(s):  
Cutting Force ◽  
Metal Cutting ◽  
Classical Model ◽  
Orthogonal Cutting ◽  
Chip Thickness ◽  
Stability Limit ◽  
Force Characteristic ◽  
Inflexion Point ◽  
The Stability ◽  
Force Characteristics

The classical model of regenerative vibration is investigated with new kinds of nonlinear cutting force characteristics. The standard nonlinear characteristics are subjected to a critical review from the nonlinear dynamics viewpoint based on the experimental results available in the literature. The proposed nonlinear model includes finite derivatives at zero chip thickness and has an essential inflexion point. In the case of the one degree-of-freedom model of orthogonal cutting, the existence of unstable self-excited vibrations is proven along the stability limits, which is strongly related to the force characteristic at its inflexion point. An analytical estimate is given for a certain area below the stability limit where stable stationary cutting and a chaotic attractor coexist. It is shown how this domain of bistability depends on the theoretical chip thickness. The comparison of these results with the experimental observations and also with the subcritical Hopf bifurcation results obtained for standard nonlinear cutting force characteristics provides relevant information on the nature of the cutting force nonlinearity.

Analysis of Oblique Cutting Forces

1967 ◽  
Vol 89 (2) ◽  
pp. 347-355 ◽  
Author(s):  
Russell F. Henke
Keyword(s):  
Steady State ◽  
Cutting Force ◽  
Cutting Forces ◽  
Metal Cutting ◽  
Single Point ◽  
Orthogonal Cutting ◽  
Cutting Process ◽  
Chip Area ◽  
Oblique Cutting ◽  
The Stability

This paper is the latest of a continuing series on the subject of self-excited machine tool chatter. The representation of the metal cutting process as required by the previously developed closed-loop chatter theory is extended to oblique cutting with tools of practical shape and geometry. The cutting process parameters essential to proper application of the stability theory are found by an analytical formulation leading to a classical eigenvalue problem. Techniques are developed to determine the steady-state constant of proportionality between resultant cutting force and uncut chip area, the direction of resultant cutting force, and the direction of maximum cutting stiffness for any single-point cutting operation. In the process, a general method to predict steady-state oblique cutting forces is evolved. The method depends on certain experimentally justifiable assumptions and utilizes previously compiled orthogonal cutting data.

Analytical Prediction of Stability Lobes in Ball End Milling

1999 ◽  
Vol 121 (4) ◽  
pp. 586-592 ◽  
Author(s):  
Y. Altıntas¸ ◽  
E. Shamoto ◽  
P. Lee ◽  
E. Budak
Keyword(s):  
Cutting Force ◽  
End Milling ◽  
Orthogonal Cutting ◽  
Chip Thickness ◽  
Transformation Method ◽  
Quadratic Equation ◽  
Analytical Prediction ◽  
Force Coefficient ◽  
Ball End Milling ◽  
Stability Lobes

The paper presents an analytical method to predict stability lobes in ball end milling. Analytical expressions are based on the dynamics of ball end milling with regeneration in the uncut chip thickness, time varying directional factors and the interaction with the machine tool structure. The cutting force coefficients are derived from orthogonal cutting data base using oblique transformation method. The influence of cutting coefficients on the stability is investigated. A computationally efficient, an equivalent average cutting force coefficient method is developed for ball end milling. The prediction of stability lobes for ball end milling is reduced to the solution of a simple quadratic equation. The analytical results agree well with the experiments and the computationally expensive and complex numerical time domain simulations.

Numerical Simulation of Metal Cutting Process Based on ANSYS/LS-DYNA

2015 ◽  
Vol 727-728 ◽  
pp. 335-338 ◽  
Author(s):  
Song Jie Yu ◽  
Di Di Wang ◽  
Xin Chen
Keyword(s):  
Cutting Force ◽  
Metal Cutting ◽  
Plastic Material ◽  
Orthogonal Cutting ◽  
Cutting Process ◽  
Machining Process ◽  
Linear Deformation ◽  
Deformation Problem ◽  
Non Linear ◽  
Elastic Plastic Material

Cutting process is a typical non-linear deformation problem, which involves material non-linear, geometry non-linear and the state non-linear problem. Based on the elastic-plastic material deformation theory, this theme established a strain hardening model. Build the simulation model of two-dimensional orthogonal cutting process of workpiece and tool by the finite element method (FEM), and simulate the changes of cutting force and the process of chip formation in the machining process, and analyzed the cutting force, the situation of chip deformation. The method is more efficient and effective than the traditional one, and provides a new way for metal cutting theory, research of material cutting performance and cutting tool product development.

Virtual Five-Axis Flank Milling of Jet Engine Impellers: Part 1 — Mechanics of Five-Axis Flank Milling

2007 ◽  
Author(s):  
W. Ferry ◽  
Y. Altintas
Keyword(s):  
Cutting Force ◽  
Cutting Forces ◽  
Orthogonal Cutting ◽  
Chip Thickness ◽  
Friction Angle ◽  
Flank Milling ◽  
Cutting Force Prediction ◽  
Jet Engine ◽  
End Mills ◽  
Five Axis

Jet engine impeller blades are flank-milled with tapered, helical, ball-end mills on five-axis machining centers. The impellers are made from difficult-to-cut titanium or nickel alloys, and the blades must be machined within tight tolerances. As a consequence, deflections of the tool and flexible workpiece can jeopardize the precision of the impellers during milling. This work is the first of a two part paper on cutting force prediction and feed optimization for the five-axis flank milling of an impeller. In Part I, a mathematical model for predicting cutting forces is presented for five-axis machining with tapered, helical, ball-end mills with variable pitch and serrated flutes. The cutter is divided axially into a number of differential elements, each with its own feed coordinate system due to five-axis motion. At each element, the total velocity due to translation and rotation is split into horizontal and vertical feed components, which are used to calculate total chip thickness along the cutting edge. The cutting forces for each element are calculated by transforming friction angle, shear stress and shear angle from an orthogonal cutting database to the oblique cutting plane. The distributed cutting load is digitally summed to obtain the total forces acting on the cutter and blade. The model can be used for general five-axis flank milling processes, and supports a variety of cutting tools. Predicted cutting force measurements are shown to be in reasonable agreement with those collected during a roughing operation on a prototype integrally bladed rotor (IBR).

Study on Determination of Friction Model at the Tool-Chip Interface of Titanium Alloy Ti6Al4V Based on Orthogonal Cutting

2011 ◽  
Vol 117-119 ◽  
pp. 1788-1791
Author(s):  
Yue Feng Yuan ◽  
Wu Yi Chen
Keyword(s):  
Titanium Alloy ◽  
Cutting Force ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Friction Model ◽  
Carbide Tool ◽  
Orthogonal Turning ◽  
Titanium Alloy Ti6al4v

It is necessary for cutting simulation to determine the friction model at the tool-chip interface suitable for metal cutting process. Cutting force experiments in orthogonal turning titanium alloy TI6AL4V are carried out with cement carbide tool KW10. The Coulomb frictions at the tool-chip interface are calculated based on measured cutting force, and the friction model is regressed, where cutting speed and feed rate are presented.

scholarly journals A thermomechanically motivated approach for identification of flow stress properties in metal cutting

2020 ◽  
Vol 111 (3-4) ◽  
pp. 1055-1068
Author(s):  
Ahmet Semih Ertürk ◽  
Amir Malakizadi ◽  
Ragnar Larsson
Keyword(s):  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Chip Thickness ◽  
Thermomechanical Coupling ◽  
Zone Model ◽  
Softening Effect ◽  
Material Parameters ◽  
Cutting Test ◽  
Temperature Distributions ◽  
Cost Efficient

Abstract The paper presents a novel thermomechanically coupled distributed primary deformation zone model to assist the inverse identification of Johnson-Cook material parameters to be used for machining simulations. A special feature of the enhanced model is that the assumed stress field is temperature-dependent, where the thermomechanical coupling governs the stress and temperature distributions across the primary shear zone to describe the thermal softening effect. By using stress, strain, strain rate, and temperature distributions from the thermomechanically enhanced model, Johnson-Cook material parameters are calibrated for orthogonal cutting tests of C38, 42CrMo4, and AA6082 materials where continuous chip formation prevails. The performance of the parameters is compared with that of a wider set of cutting tests using finite element simulations. The results show that the thermomechanically motivated model yields closer results to experiments in terms of cutting force and chip thickness (9% and 34% difference, respectively) compared with the original thermally uncoupled model (47% and 92% difference, respectively). Identification of the material parameters by this method focuses directly on the orthogonal cutting test and it does not require many experiments or simulations. In fact, the proposed methodology is computationally robust and cost-efficient which makes it preferable compared with other methods which are more accurate but highly time-consuming.

Modeling the Chip-Work Contact Force for Chip Breaking in Orthogonal Machining With a Flat-Faced Tool

1998 ◽  
Vol 120 (1) ◽  
pp. 49-56 ◽  
Author(s):  
B. K. Ganapathy ◽  
I. S. Jawahir
Keyword(s):  
Cutting Force ◽  
Contact Force ◽  
Cutting Forces ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Force Model ◽  
Two Dimensional ◽  
Cutting Force Model ◽  
Chip Breaking ◽  
Orthogonal Machining

The present tendency towards increased automation of metal cutting operations has resulted in a need to develop a model for the chip breaking process. Conventional cutting force models do not have any provision for the study of chip breaking since they assume a continuous mode of chip formation, where the contact action of the free-end of the chip is ignored in all analyses. The new cutting force model proposed in this work incorporates the contact force developed due to the free-end of the chip touching the workpiece, and is applicable to the study of two-dimensional chip breaking in orthogonal machining. Orthogonal cutting tests were performed to obtain two-dimensional chip breaking. The experimentally measured cutting forces show a good correlation with the estimated cutting forces using the model. Results show that the forces acting on the chip vary within a chip breaking cycle and help identify the chip breaking event.

scholarly journals VALIDATION OF CUTTING FORCE CHARACTERISTIC FOR COMPLEX TOOLPATH

2016 ◽  
Vol 3 ◽  
pp. 78-81
Author(s):  
Henrik Tamás Sykora ◽  
Attila Kovács ◽  
Dániel Bachrathy
Keyword(s):  
Cutting Force ◽  
Tool Path ◽  
Removal Rate ◽  
Chip Thickness ◽  
Simulation Method ◽  
Milling Process ◽  
Simulation Software ◽  
Force Characteristic ◽  
Force Model ◽  
Force Data

In the design phase of the milling process, there is a great need for the prediction of the cutting force, the required torque and power of the spindle. These informations could be used to optimize the tool path and improve the material removal rate. In this work, we present our dexel based simulation software, its modules, calculations steps and the simulation method. Different force models were analysed to describe the specific force as a function of the local chip thickness. The models were fitted to the measured force data. Then the selected force model was validated in case of a complex tool path.

The Constant Force Component due to Material Separation and Its Contribution to the Size Effect in Specific Cutting Energy

2005 ◽  
Vol 128 (3) ◽  
pp. 811-815 ◽  
Author(s):  
Sathyan Subbiah ◽  
Shreyes N. Melkote
Keyword(s):  
Size Effect ◽  
Cutting Force ◽  
Orthogonal Cutting ◽  
Chip Thickness ◽  
Constant Force ◽  
Specific Cutting Energy ◽  
Force Component ◽  
Uncut Chip Thickness ◽  
Cutting Energy ◽  
Material Separation

The contribution of material separation in cutting ductile metals to the constant force component, and, hence, to the size effect in specific cutting energy is explored in this paper. A force-decomposition-based framework is proposed to reconcile the varied reasons given in literature for the size effect. In this framework, the cutting force is broken down into three components: one that is decreasing, another that is increasing, and the third that remains constant, with decreasing uncut chip thickness. The last component is investigated by performing orthogonal cutting experiments on OFHC copper at high rake angles of up to 70deg in an attempt to isolate it. As the rake angle is increased, the resulting experimental data show a trend toward a constant cutting-force component independent of the uncut chip thickness. Visual evidence of ductile tearing ahead of the tool associated with material separation leading to chip formation is shown. The measured constant force and the force needed for ductile crack extension are then compared.

Experimental and Analytical Investigation of Self-Excited Chatter Vibrations in Metal Cutting

1978 ◽  
Vol 100 (1) ◽  
pp. 92-99
Author(s):  
N. Saravanja-Fabris ◽  
A. F. D’Souza
Keyword(s):  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Analytical Investigation ◽  
Point Of View ◽  
Cutting Process ◽  
Describing Function ◽  
Describing Functions ◽  
Machine Tool Structure ◽  
Excited Vibration ◽  
The Stability

Chatter in metal cutting is a nonlinear self-excited vibration of the limit cycle type. This investigation is concerned with the analysis of chatter from the viewpoint of the describing function. Vibrations with different frequencies and amplitudes were superimposed on the steady feed motion of the tool in orthogonal cutting in order to simulate chatter. The relationships between the oscillating cutting and thrust forces and tool vibrations are discussed from the point of view of energy transfer and describing functions. Experimentally obtained describing functions of the dynamically varying cutting process are given. The stability of a typical machine tool structure under primary chatter conditions with dynamical cutting process represented by its describing function is discussed.

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