Stochastic Cutting Force Modeling and Prediction in Machining

Author(s):  
Yang Liu ◽  
Zhenhua Xiong ◽  
Zhanqinag Liu

Abstract As the cutting force plays an important role in machining, the modeling of cutting force has drawn considerable interests in recent years. However, most of current methods were focused on the deterministic modeling of cutting force, while the inherent stochasticity of cutting force is rarely considered for general metal cutting machining. Thus, a stochastic model is proposed in this paper to predict the stochastic cutting force by considering realistic cutting conditions, including the inhomogeneity of cutting material and the multi-mode machining system. Specifically, we transform the constant cutting coefficient in previous models into a stationary Gaussian process in the proposed stochastic model. As for the tool vibration, the uncut chip thickness is also modeled in a stochastic manner. Moreover, it is found that the random cutting coefficients can be estimated conveniently through experiments and effectively simulated by stochastic differential equations at any timescale. Then, the stochastic cutting force can be predicted numerically by combining the stochastic model and the multi-mode dynamic equations. For verification, a three-mode machining system was set up, and workpieces with different metal alloys were tested. It is found that the random cutting coefficients estimated are insensitive to cutting parameters, and the prediction results show satisfactory agreement with experimental results in both time and statistical domains. The proposed method can provide rich statistical information of cutting forces, which can facilitate related applications like tool condition monitoring when the on-line measurement of cutting force is not preferred or even impossible.

1999 ◽  
Author(s):  
J. R. Pratt ◽  
M. A. Davies ◽  
M. D. Kennedy ◽  
T. Kalmár-Nagy

Abstract A single-degree-of-freedom active cutting fixture is employed to reveal and analyse the hysteretic nature of the lobed stability boundary in a simple machining experiment. Specifically, the seventh stability lobe of a regenerative cutting process is mapped using experimental, analytical, and computational techniques. Then, taking width of cut as a control parameter, the transition from stable cutting to chatter is observed experimentally. The cutting stability is found to possess a substantial hysteresis so that either stable or chattering tool motions can exist at the same nominal cutting parameters, depending on initial conditions. This behavior is predicted by applying nonlinear regenerative chatter theory to an empirical characterization of the cutting force dependence on chip thickness. Time-domain simulations that incorporate both the nonlinear cutting force dependence on chip thickness and the multiple-regenerative effect due to the tool leaving the cut are shown to agree both qualitatively and quantitatively with experiment.


2016 ◽  
Vol 836-837 ◽  
pp. 88-93
Author(s):  
Hui Sun ◽  
Hu Xiao ◽  
Liang Li

In order to improve the rough machining efficiency of titanium alloy, experiments were carried out to investigate the influence of feed per tooth on cutting force and cutting power with index-able coated carbide inserts. The curves of cutting parameters, including cutting force and cutting power, were obtained by single factor test. The results showed that, as the feed per tooth increases, the cutting force increases, especially in the direction of cutting width. All forces almost changed linearly with the changing of feed, and the cutting force of feed direction was the smallest force among the three directions of cutting force. The analytical model of tangential cutting force in the x-y plane was established. By calculating average chip thickness and relationships between tangential cutting force and measurements of cutting force to predict the cutting power, the calculation results were accurate which compared with the actual output power of the machine tool.


2018 ◽  
Vol 14 (1) ◽  
pp. 67-76
Author(s):  
Mohanned Mohammed H. AL-Khafaji

The turning process has various factors, which affecting machinability and should be investigated. These are surface roughness, tool life, power consumption, cutting temperature, machining force components, tool wear, and chip thickness ratio. These factors made the process nonlinear and complicated. This work aims to build neural network models to correlate the cutting parameters, namely cutting speed, depth of cut and feed rate, to the machining force and chip thickness ratio. The turning process was performed on high strength aluminum alloy 7075-T6. Three radial basis neural networks are constructed for cutting force, passive force, and feed force. In addition, a radial basis network is constructed to model the chip thickness ratio. The inputs to all networks are cutting speed, depth of cut, and feed rate. All networks performances (outputs) for all machining force components (cutting force, passive force and feed force) showed perfect match with the experimental data and the calculated correlation coefficients were equal to one. The built network for the chip thickness ratio is giving correlation coefficient equal one too, when its output compared with the experimental results. These networks (models) are used to optimize the cutting parameters that produce the lowest machining force and chip thickness ratio. The models showed that the optimum machining force was (240.46 N) which can be produced when the cutting speed (683 m/min), depth of cut (3.18 mm) and feed rate (0.27 mm/rev). The proposed network for the chip thickness ratio showed that the minimum chip thickness is (1.21), which is at cutting speed (683 m/min), depth of cut (3.18 mm) and feed rate (0.17 mm/rev).


2013 ◽  
Vol 710 ◽  
pp. 223-227
Author(s):  
Yan Cao ◽  
Hua Chen ◽  
Hai Xia Zhao

Based on the study on metal cutting theories and rigid-plastic finite element method, taking Sweden SECO lathe tool MDT as the researching object, the cutting force in cutting process is analyzed after a cutting process simulation model is constructed using finite element method. Different simulation parameters and cutting parameters are used to carry out analyses time after time. The dynamic changing curves of the cutting force in cutting process are obtained. Through the comparison of the cutting force in different cutting conditions, the influence of cutting parameters on the cutting force is summarized. The research can provide useful data for improvement of metal cutting technology and tool cutting performance.


2013 ◽  
Vol 641-642 ◽  
pp. 367-370
Author(s):  
Gui Qiang Liang ◽  
Fei Fei Zhao

Abstract In the present study, an attempt has been made to investigate the effect of cutting parameters (cutting speed, feed rate and depth of cut) on cutting forces (feed force, thrust force and cutting force) and surface roughness in milling of Quartz glas using diamond wheel. The cutting process in the up-cut milling of glass is discussed and the cutting force measured. The cutting force gradually increases with the cutter rotation at the beginning of the cut, and oscillates about a constant mean value after a certain undeformed chip thickness. The results show that cutting forces and surface roughness do not vary much with experimental cutting speed in the range of 55–93 m/min. The suggested models of cutting forces and surface roughness and adequately map within the limits of the cutting parameters considered.


2011 ◽  
Vol 314-316 ◽  
pp. 900-903
Author(s):  
Yan Cao ◽  
Hua Chen ◽  
Hai Xia Zhao

On the basis of metal cutting and rigid-plastic finite element theories, taking cutting force in turning process as the research object, a FEA model for turning process using a MDT cutter on a centre lathe CA6140 is constructed to simulate its metal cutting process. Using Deform 3D, cutting forces are calculated according to different cutting parameters. The influences of the cutting parameters on the cutting forces are investigated. In order to validate the FEA model, cutting experiments are conducted. Comparison between simulated cutting forces and experimental forces shows similar trends and reasonable agreement.


Author(s):  
Yong Zhao ◽  
Robert B. Jerard ◽  
Barry K. Fussell

This paper introduces a method to use the cutting force profile, measured from a Kistler dynamometer, to calibrate a mechanistic based force model containing four cutting coefficients. The undesirable effects of tool vibration and force sensor dynamics are minimized by carefully choosing experimental conditions. Cutting force profiles provide an array of force versus chip thickness based values that can be used in a regression fit to find the model coefficients. Results show that different ranges of chip thickness used in the calibration process result in slightly different cutting coefficients, which implies chip thickness has an effect on cutting coefficients. The force profile based cutting coefficients are then used in the cutting force model to estimate the peak resultant cutting force. Comparison of model estimates and measured values show less than 10% error.


Author(s):  
Zoltan Dombovari ◽  
R. Eddie Wilson ◽  
Gabor Stepan

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.


SINERGI ◽  
2020 ◽  
Vol 24 (3) ◽  
pp. 171
Author(s):  
Sobron Yamin Lubis ◽  
Sofyan Djamil ◽  
Yehezkiel Kurniawan Zebua

In the machining of metal cutting, cutting tools are the main things that must be considered. Using improper cutting parameters can cause damage to the cutting tool. The damage is Built-Up Edge (BUE). The situation is undesirable in the metal cutting process because it can interfere with machining, and the surface roughness value of the workpiece becomes higher. This study aimed to determine the effect of cutting speed on BUE that occurred and the cutting strength caused. Five cutting speed variants are used. Observation of the BUE process is done visually, whereas to determine the size of BUE using a digital microscope. If a cutting tool occurs BUE, then the cutting process is stopped, and measurements are made. This study uses variations in cutting speed consisting of cutting speed 141, 142, 148, 157, 163, and 169 m/min, and depth of cut 0.4 mm. From the results of the study were obtained that the biggest feeding force is at cutting speed 141 m/min at 347 N, and the largest cutting force value is 239 N with the dimension of BUE length: 1.56 mm, width: 1.35 mm, high: 0.56mm.


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