Analytical Modeling of Process Damping in Machining

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Oguzhan Tuysuz ◽  
Yusuf Altintas
Keyword(s):  
Contact Pressure ◽  
End Milling ◽  
Cutting Edge ◽  
Machining Process ◽  
Chatter Stability ◽  
Experimental Calibration ◽  
Process Damping ◽  
Low Speed ◽  
Edge Geometry ◽  
Five Axis

The machining process induced damping caused by the indentation of the cutting edge into the wavy cut surface greatly affects the process stability in low-speed machining of thermally resistant alloys and hardened steel, which have high-frequency vibration marks packed with short wavelengths. This paper presents an analytical model to predict the process damping forces and chatter stability in low-speed machining operations. The indentation boundaries are evaluated using the cutting edge geometry and the undulated surface waveform. Contact pressure due to the interference of the rounded and straight sections of the rigid cutting edge with the elastic-plastic work material is analytically estimated at discrete positions along the wavy surface. The overall contact pressure is obtained as a function of the cutting edge geometry, vibration frequency and amplitude, and the material properties of the workpiece. The resulting specific indentation force is evaluated by integrating the overall pressure along the contact length. Then, the process damping force is linearized by an equivalent specific viscous damping, which is used in the frequency domain chatter stability analysis. The newly proposed analytical process damping model is experimentally validated by predicting the chatter stability in orthogonal turning, end milling, and five-axis milling of flexible blades. It is shown that the proposed model can replace currently used empirical models, which require extensive experimental calibration approach or computationally prohibitive finite elements based numerical simulation methods.

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.

Drehen von ausferritischem Gusseisen*/Turning of austempered ductile iron – Impact of inhomogeneous cutting edge geometry on wear mechanism and machining result

2018 ◽  
Vol 108 (10) ◽  
pp. 736-742
Author(s):  
J. Hartig ◽  
B. Kirsch ◽  
J. Aurich
Keyword(s):  
Tungsten Carbide ◽  
Tool Life ◽  
Wear Mechanism ◽  
Ductile Iron ◽  
Cutting Edge ◽  
Machining Process ◽  
Austempered Ductile Iron ◽  
Machining Performance ◽  
Edge Geometry ◽  
Homogeneous Preparation

Mit Schneidkantenpräparation kann das Werkzeug im Zerspanprozess an die Bearbeitungsaufgabe angepasst werden. Homogene Präparationen können dabei entweder auf hohe Belastungen des Werkzeugs oder ein optimiertes Bearbeitungsergebnis im Sinne der Oberfläche ausgelegt werden. In diesem Beitrag wurden die Schneidkanten von Hartmetall-Wendeschneidplatten unterschiedlich inhomogen präpariert, um den unterschiedlichen Anforderungen entlang des Eingriffs Rechnung zu tragen. Neben der Werkzeugstandzeit wurde das Prozessergebnis beim Außenlängs-Runddrehen von ausferritischem Gusseisen (ADI) 900 untersucht.   The preparation of cutting edges allows for tools to be tailored to the machining process. A homogeneous preparation can either be designed for high loads in the machining process or an optimized machining result on the surface. In this article, the cutting edges of tungsten carbide indexable inserts were prepared inhomogeneously and thus individually matched to the machining task. Tool life and machining performance while turning austempered ductile iron (ADI) 900 were investigated.

scholarly journals Experimental and simulation study on chatter stability region of integral impeller with non-uniform allowance

2020 ◽  
Vol 103 (3) ◽  
pp. 003685042093341
Author(s):  
Yan Wu ◽  
Kaifa Wang ◽  
Gang Zheng ◽  
Boxin Lv ◽  
Yong He
Keyword(s):  
Natural Frequency ◽  
Stability Region ◽  
Tool Path ◽  
Surface Profile ◽  
Machining Process ◽  
Chatter Stability ◽  
Element Analysis ◽  
Impeller Blade ◽  
Five Axis ◽  
Milling Chatter

In order to accurately improve and predict chatter stability region of machining process, an optimization method of machining process with non-uniform allowance of integral impeller was proposed. The modal parameters of the workpiece process system were obtained using the finite element analysis. Based on the regenerative chatter analysis theory, a limit comparison diagram of the stability with uniform allowance and non-uniform allowance was established. The simulation results showed that the non-uniform allowance natural frequency is about 1.43 times as much as the uniform allowance natural frequency, and the machining system stiffness non-uniform allowance is twice as much as the uniform allowance, while the limit of chatter stability region is increased by 3 times. This article studied uniform allowance and non-uniform allowance of milling chatter stability with experimental method. Tool path for five-axis machining and machine tool simulation based on NX CAM were planned. The comparisons of cutting processing uniform allowance and non-uniform allowance were done, and the surface profile detection of the test part with the three-dimensional scanning was carried out. The experimental results showed that the average optimization rate for manufacturing precision of blade suction surface after optimization and pressure surface was 63.8% and 48.84%. The total experiment showed that this process optimization strategy could effectively improve the stiffness of the integral impeller blade and reduce the cutting chatter of the blade during the cutting process.

scholarly journals Mechanics and Dynamics of Serrated End Mills

Manufacturing ◽  
2002 ◽  
Author(s):  
S. Doruk Merdol ◽  
Yusuf Altintas
Keyword(s):  
Time Domain ◽  
Cutting Forces ◽  
Chip Thickness ◽  
Cutting Edge ◽  
Chatter Stability ◽  
Edge Point ◽  
Oblique Cutting ◽  
Edge Geometry ◽  
End Mills ◽  
Chatter Stability Lobes

Mechanics and dynamics of serrated milling cutters are presented in the article. The serrated flute design knots are fitted to a cubic spline, which is then projected on helical flutes. Cutting edge geometry at any point along the serrated flute is represented by its immersion angle and tangent vectors in radial, tangential and helix directions. The chip thickness removed by each cutting edge point is determined by using previously proposed exact kinematics of dynamic milling. The cutting forces are evaluated by orthogonal to oblique cutting mechanics transformation. The experimentally proven model is able to predict the cutting forces and chatter stability lobes in time domain.

Identification of Machining Process Damping Using Output-Only Modal Analysis

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
K. Ahmadi ◽  
Y. Altintas
Keyword(s):  
Orthogonal Cutting ◽  
Machining Process ◽  
Damping Coefficient ◽  
Chatter Stability ◽  
Force Coefficient ◽  
Workpiece Material ◽  
Process Damping ◽  
Indentation Force ◽  
Output Only ◽  
Cutting Speeds

The existing chatter stability prediction algorithms fail in low-speed machining of difficult to cut alloys, unless process damping contributed by the tool flank face–finish surface contact is considered. This paper presents a new method in predicting the material dependent process damping coefficient from chatter free orthogonal cutting tests. An equivalent process damping coefficient of the dynamic system is estimated from the frequency domain decomposition (FDD) of the vibration signals measured during stable cutting tests. Subsequently, the specific indentation force of the workpiece material is identified from the process damping coefficients obtained over a range of cutting speeds. The specific indentation force coefficient is used in an explicit formula of process damping which considers the radius and clearance angle of the cutting edge. It is experimentally shown that when the proposed process damping model is included, the accuracy of chatter stability predictions in turning and milling improves significantly at low cutting speeds.

Mechanics and Dynamics of Serrated Cylindrical and Tapered End Mills

2004 ◽  
Vol 126 (2) ◽  
pp. 317-326 ◽  
Author(s):  
S. D. Merdol ◽  
Y. Altintas
Keyword(s):  
Cutting Forces ◽  
Chip Thickness ◽  
Cutting Edge ◽  
Chatter Stability ◽  
Edge Point ◽  
Edge Geometry ◽  
Proposed Model ◽  
Chatter Vibrations ◽  
End Mills ◽  
Chatter Stability Lobes

Serrated end mills are effectively used in suppressing chatter vibrations in roughing operations. Mechanics and dynamics of serrated cylindrical and tapered helical end mills are presented in the article. The serrated flute design knots are fitted to a cubic spline, which is then projected on helical flutes. Cutting edge geometry at any point along the serrated flute is represented by its immersion angle and tangent vectors in radial, tangential and helical directions. The chip thickness removed by each cutting edge point is determined by using exact kinematics of dynamic milling. The cutting forces are evaluated by orthogonal to oblique cutting mechanics transformation. The experimentally proven model is able to predict the cutting forces and chatter stability lobes in time domain. It is shown that the proposed model can be used in evaluating the performance of serrated end mills during their stage.

Multi-scale prediction of the geometrical deviations of the surface finished by five-axis ball-end milling

2015 ◽  
Vol 231 (10) ◽  
pp. 1685-1702 ◽  
Author(s):  
Bo Li ◽  
Yanlong Cao ◽  
Xuefeng Ye ◽  
Jiayan Guan ◽  
Jiangxin Yang
Keyword(s):  
Machine Tool ◽  
End Milling ◽  
Dynamic Properties ◽  
Machining Process ◽  
Machined Surface ◽  
Multi Scale ◽  
Geometrical Errors ◽  
Macro Scale ◽  
Five Axis

Surface quality and accuracy are the main factors which affect the performance and life cycle of the products. Due to the complexity of the machining process, it is difficult to evaluate the machined surface real time. Simulation of the machining process became the main method to predict and control the quality of the machined surface. This article developed a multi-scale simulation system to predict the overall geometrical features of the milled surface. The effects of locating errors, geometrical errors of the machine tool and tool deflections on the quality of the machined surface are included in the proposed model. Also, different strategies are employed to evaluate the macro-scale and micro-scale geometrical deviations of the machined surface to balance the time cost and accuracy. In comparison with the traditional method, both the form deviations and roughness feature of the machined surface can be predicted. Since the static and dynamic properties of the machining system were considered, both the stable and unstable cutting conditions can be analyzed by using the proposed method. At the end of this article, case studies are carried out to validate the proposed method. The effects of the locating errors, geometrical errors of the machine tool and cutting parameters on the quality of the machined surface are analyzed. The significance of their influences on the quality of the machined surface was investigated.

scholarly journals Study on the Design and Cutting Performance of a Revolving Cycloid Milling Cutter

2019 ◽  
Vol 9 (14) ◽  
pp. 2915 ◽  
Author(s):  
Guangyue Wang ◽  
Xianli Liu ◽  
Weijie Gao ◽  
Bingxin Yan ◽  
Tao Chen
Keyword(s):  
Titanium Alloy ◽  
End Milling ◽  
Tangential Force ◽  
Boundary Curve ◽  
Cutting Performance ◽  
Machining Process ◽  
Rake Face ◽  
Milling Cutter ◽  
Ball End Milling ◽  
Five Axis

Problems such as low machining efficiency, severe tool wear and difficulty in safeguarding surface quality always exist in the machining process of titanium alloy with ball-end milling cutters. To address these issues, the design and manufacture of a revolving cycloid milling cutter for titanium alloy processing were studied in this paper. Firstly, the mathematical model of the revolving cycloid milling cutter contour surface was established. The parametric equation of an orthogonal helix cutting edge curve of a revolving cycloid milling cutter is presented. Then, the bottom boundary curve of the rake face is introduced. The five-axis grinding trajectory equation of revolving cycloid milling cutter rake face was derived based on the edge curve equation and coordinate transformation. Next, fabricating the revolving cycloid milling cutter and detecting the grinding accuracy of tool profile and geometric angle were performed. At last, a contrast test regarding the performance of the revolving cycloid milling cutter and the ball-end milling cutter in cutting titanium alloy TC11 was carried out. According to the test results, in comparison to the ball-end milling cutter, the revolving cycloid milling cutter had a smaller ratio of the axial force to the tangential force. Moreover, its flank face wore more slowly and evenly. As a result, a good surface processing quality can be maintained even under larger wear conditions, demonstrating an outstanding cutting performance.

Sign in / Sign up

Export Citation Format

Share Document