Estimation of in-process cutting constants in ball-end milling

Author(s):  
C M Zheng ◽  
J -J Junz Wang

Two methods are presented for the estimation of tangential, radial and axial cutting coefficients for the shearing and ploughing mechanisms from a single set of cutting forces in ball-end milling. These estimation methods are based upon the invertibility of the analytical milling force model, which considers both the shearing and the ploughing mechanisms by incorporating their respective cutting constants in the local force model. The periodic milling forces are established as the convolution integral of the differential local cutting forces and their Fourier coefficients are derived and expressed in a matrix expression as a linear function of the unknown cutting constants in terms of cutting conditions and cutter geometry. This linear expression thus leads to a systematic formulation of the estimation methods allowing the six unknown cutting constants to be determined from the measured milling forces. The first method uses the first harmonic forces as the source signal while the second method extracts the six cutting constants from the average force as well as the first harmonics. Limitations of both estimation methods are discussed. The consistency and accuracy of the estimated cutting constants are confirmed by the experimental results.

Author(s):  
Bryan Javorek ◽  
Barry K. Fussell ◽  
Robert B. Jerard

Changes in cutting forces during a milling operation can be associated with tool wear and breakage. Accurate monitoring of these cutting forces is an important step towards the automation of the machining process. However, direct force sensors, such as dynamometers, are not practical for industry application due to high costs, unwanted compliance, and workspace limitations. This paper describes a method in which power sensors on the feed and spindle motors are used to generate coefficients for a cutting force model. The resulting model accurately predicts the X and Y cutting forces observed in several simple end-milling tests, and should be capable of estimating both the peak and average force for a given cut geometry. In this work, a dynamometer is used to calibrate the feed drive power sensor and to measure experimental cutting forces for verification of the cutting force model. Measurement of the average x-axis cutting forces is currently presented as an off-line procedure performed on a sacrificial block of material. The potential development of a continuous, real-time force monitoring system is discussed.


2001 ◽  
Author(s):  
Richard Y. Chiou ◽  
Bing Zhao

Abstract This paper presents an analytical convolution model of dynamic cutting forces in ball end milling of 3-D plane surfaces. The model takes into account the instantaneous slope on a sculptured surface to establish the chip geometry in cutting force calculation algorithm. A three-dimensional model of cutting forces in ball end milling is presented in terms of material properties, cutting parameters, machining configuration, and tool/work geometry. Based on the relationship of the local cutting force, chip load and engaged boundary, the total cutting force model is established via the angle domain convolution integration of the local forces in the feed, cross feed, axial direction, and inclination angle. The convolution integral leads to a periodic function of cutting forces in the angle domain and an explicit expression of the dynamic cutting force components in the frequency domain. Following the theoretical analysis, experimental study is discussed to illustrate the implementation procedure for force identification, and frequency domain data are presented to verify the analytical results.


2013 ◽  
Vol 1 (1) ◽  
Author(s):  
Mehdi Mahmoodi ◽  
M. G. Mostofa ◽  
Martin Jun ◽  
Simon S. Park

Carbon nanotube (CNT) based polymeric composites exhibit high strength and thermal conductivity and can be electrically conductive at a low percolation threshold. CNT nanocomposites with polystyrene (PS) thermoplastic matrix were injection-molded and high shear stress in the flow direction enabled partial alignment of the CNTs. The samples with different CNT concentrations were prepared to study the effect of CNT concentration on the cutting behavior of the samples. Characterizations of CNT polymer composites were studied to relate different characteristics of materials such as thermal conductivity and mechanical properties to micromachining. Micro-end milling was performed to understand the material removal behavior of CNT nanocomposites. It was found that CNT alignment and concentrations influenced the cutting forces. The mechanistic micromilling force model was used to predict the cutting forces. The force model has been verified with the experimental milling forces. The machinability of the CNT nanocomposites was better than that of pure polymer due to the improved thermal conductivity and mechanical characteristics.


1999 ◽  
Author(s):  
Hsi-Yung (Steve) Feng ◽  
Ning Su

Abstract The prediction and optimization of cutting forces in the finishing machining of 3D plane surfaces using ball-end milling are presented in this paper. The cutting force model is developed based on the mechanistic modeling approach. This improved model is able to accurately predict the cutting forces for non-horizontal and cross-feed cutter movements typical in 3D finishing ball-end milling. Optimization of the cutting forces is used to determine both the tool path and the maximum feed rate in 3D plane surface finishing machining. The objective is to achieve highest machining efficiency and to ensure product quality. Experimental results have shown that the cutting force model gives excellent predictions of cutting forces in 3D finishing ball-end milling. The feasibility of the integrated process planning method has been demonstrated through the establishment of optimized process plans for the finishing machining of 3D plane surfaces.


2019 ◽  
Vol 13 (3) ◽  
pp. 232-240
Author(s):  
Zhixin Feng ◽  
Meng Liu ◽  
Guohe Li

Background: Calibration of cutting coefficients is the key content in modeling a mechanistic cutting force model. Generally, in modeling cutting force for ball end milling, the tangent, radial and binormal cutting force coefficients are each considered as a polynomial, respectively. This fact is due to the dependency between the cutting force coefficients and the cutting edge inclination angle which is variable in ball-end mills. Objective: This paper presents an approach to determine the polynomial cutting force coefficients. Methods: In this approach, the cutting force coefficients are expressed as explicit linear equations about the average slotting forces. After analysis of the least square regression method which is utilized in the cutting coefficients evaluation, the principle of cutting parameters choice in calibration experiment and the relationship between the order of polynomial and the number of experiments are presented. Besides, a lot of patents on identification of polynomial cutting coefficients for milling force model were studied. Results: Finally, a series of semi-slotting verification cutting tests were arranged, the measured force agrees well with the predicted force, which demonstrates the effectiveness of this approach. Conclusion: Based on the calibration method proposed in this paper, the cutting coefficients can be determined through (m+2) slotting experiments for m-degree shearing coefficients polynomial theoretically.


1996 ◽  
Vol 118 (1) ◽  
pp. 95-103 ◽  
Author(s):  
G. Yu¨cesan ◽  
Y. Altıntas¸

Mechanics of milling with ball ended helical cutters are modeled. The model is based on the analytic representation of ball shaped helical flute geometry, and its rake and clearance surfaces. It is assumed that friction and pressure loads on the rake face are proportional to the uncut chip thickness area. The load on the flank contact face is concentrated on the in cut portion of the cutting edge. The pressure and friction coefficients are identified from a set of slot ball end milling tests at different feeds and axial depth of cuts, and are used to predict the cutting forces for various cutting conditions. The experimentally verified model accurately predicts the cutting forces in three Cartesian directions.


2014 ◽  
Vol 800-801 ◽  
pp. 337-341 ◽  
Author(s):  
Yun Peng Ding ◽  
Xian Li Liu ◽  
Hui Nan Shi ◽  
Jiao Li ◽  
Rui Zhang

In this paper, a cutting force model in ball end milling of mold cavity corner is established. Based on infinitesimal milling force model, cutting element of ball end milling cutter is treated as equal diameter end milling cutter, then determine the location of points when the micro-element participated in the cutting, and the tool-workpiece contact area and cutting range is determined. Thereby a complete milling force model in corner machining with ball end milling cutter is established.


2011 ◽  
Vol 223 ◽  
pp. 701-712 ◽  
Author(s):  
Yaman Boz ◽  
Huseyin Erdim ◽  
Ismail Lazoglu

5-axis ball-end milling processes are used in various industries such as aerospace, automotive, die-mold and biomedical industries. 5-axis machining provides reduced cycle times and more accurate machining via reduction in machining setups, use of shorter tools due to improved tool accessibility. However, desired machining productivity and precision can be obtained by physical modeling of machining processes via appropriate selection of process parameters. In response to this gap in the industry this paper presents a cutting force model for 5-axis ball-end milling cutting force prediction. Cutter-workpiece engagement is extracted via developed solid modeler based engagement model. Simultaneous 5-axis milling tests are conducted on Al7075 workpiece material with a carbide cutting tool. Validation of the proposed model is performed for impeller hub roughing toolpaths. Validation test proves that presented model is computationally efficient and cutting forces can be predicted reasonably well. The result of validation test and detailed comparison with the simulation are also presented in the paper.


2000 ◽  
Vol 123 (1) ◽  
pp. 23-29 ◽  
Author(s):  
Hsi-Yung Feng ◽  
Ning Su

This paper presents an improved mechanistic cutting force model for the ball-end milling process. The objective is to accurately model the cutting forces for nonhorizontal and cross-feed cutter movements in 3D finishing ball-end milling. Main features of the model include: (1) a robust cut geometry identification method to establish the complicated engaged area on the cutter; (2) a generalized algorithm to determine the undeformed chip thickness for each engaged cutting edge element; and (3) a comprehensive empirical chip-force relationship to characterize nonhorizontal cutting mechanics. Experimental results have shown that the present model gives excellent predictions of cutting forces in 3D ball-end milling.


1999 ◽  
Vol 122 (1) ◽  
pp. 3-11 ◽  
Author(s):  
Ismail Lazoglu ◽  
Steven Y. Liang

In the machining of sculpture surfaces with ball-end mill, the cutter axis or workpiece is often inclined to generate an admissible orientation. This paper primarily presents an enhanced cutting force model for ball-end milling with cutter axis inclination. It involves the kinematic reasoning of cutting edge geometry, local helix angle and average chip thickness followed by the analysis of effects of axis inclination in the contact zone between cutter and workpiece. Thereupon, development of the analytical force model for inclined-axis machining is achieved using cutter angle domain convolution method. Experimental evaluation of the model is discussed, and experimental results and model predictions under various cutting conditions are compared in the frequency as well as in the angular domain. [S1087-1357(00)70601-0]


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