scholarly journals Modeling and Estimation of Cutting Forces in Ball Helical Milling Process

Author(s):  
Haiyan Wang ◽  
Kexin Tao ◽  
Tian Jin

Abstract Milling forces play an important role in the milling process and are generally calculated by the mechanistic or numerical methods, reliable model of cutting force is very important for the simulation of milling process, which has big scientific significance to further improve machining quality. Ball helical milling technology is used to make holes based on the cutting principle of helical milling using ball end cutter, due to the influence of spherical surface machining characteristic, the modeling of cutting force in ball helical milling is difficult. Therefore, the main purpose of this paper is to first establish an analytical cutting force model in the ball helical milling process. Considering cutting characteristics in the axial feed, the kinematics of ball helical milling is first presented, then the chip thickness distribution in different directions along the cutting edges are predicted. Furthermore, based on the characteristics of helical milling technology and geometry shape of ball end mill and the classical mechanical cutting force model, through the study on the ball-end milling mechanics, a new relatively accurate theoretical cutting force model is established. At the same time, cutting force coefficients are identified through instantaneous force method according to the Ti-alloy experimental research result. Finally, higher simulation precision of cutting force model in ball helical milling process is received.

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.


Author(s):  
Xuewei Zhang ◽  
Tianbiao Yu ◽  
Wanshan Wang

An accurate prediction of cutting forces in the micro end milling, which is affected by many factors, is the basis for increasing the machining productivity and selecting optimal cutting parameters. This paper develops a dynamic cutting force model in the micro end milling taking into account tool vibrations and run-out. The influence of tool run-out is integrated with the trochoidal trajectory of tooth and the size effect of cutting edge radius into the static undeformed chip thickness. Meanwhile, the real-time tool vibrations are obtained from differential motion equations with the measured modal parameters, in which the process damping effect is superposed as feedback on the undeformed chip thickness. The proposed dynamic cutting force model has been experimentally validated in the micro end milling process of the Al6061 workpiece. The tool run-out parameters and cutting forces coefficients can be identified on the basis of the measured cutting forces. Compared with the traditional model without tool vibrations and run-out, the predicted and measured cutting forces in the micro end milling process show closer agreement when considering tool vibrations and run-out.


2011 ◽  
Vol 188 ◽  
pp. 404-409 ◽  
Author(s):  
Xue Yan ◽  
Hua Tao ◽  
D.H. Zhang ◽  
B.H. Wu

A developed method to predict the cutting forces in end milling of generalized corners is proposed in this paper. The cornering milling process is divided into a series of cutting segments with different cutting states. The mathematical model of the geometric relationship between cutter and the corner profile is established for each segment. Cutting forces is predicted by introducing the classical cutting force model. The computational results of cutting forces are in good agreement with experimental data.


2006 ◽  
Vol 2 (2) ◽  
pp. 167-179 ◽  
Author(s):  
R. P. H. Faassen ◽  
N. van de Wouw ◽  
H. Nijmeijer ◽  
J. A. J. Oosterling

The efficiency of the high-speed milling process is often limited by the occurrence of chatter. In order to predict the occurrence of chatter, accurate models are necessary. In most models regarding milling, the cutter is assumed to follow a circular tooth path. However, the real tool path is trochoidal in the ideal case, i.e., without vibrations of the tool. Therefore, models using a circular tool path lead to errors, especially when the cutting angle is close to 0 or π radians. An updated model for the milling process is presented which features a model of the undeformed chip thickness and a time-periodic delay. In combination with this tool path model, a nonlinear cutting force model is used, to include the dependency of the chatter boundary on the feed rate. The stability of the milling system, and hence the occurrence of chatter, is investigated using both the traditional and the trochoidal model by means of the semi-discretization method. Due to the combination of this updated tool path model with a nonlinear cutting force model, the periodic solution of this system, representing a chatter-free process, needs to be computed before the stability can be investigated. This periodic solution is computed using a finite difference method for delay-differential equations. Especially for low immersion cuts, the stability lobes diagram (SLD) using the updated model shows significant differences compared to the SLD using the traditional model. Also the use of the nonlinear cutting force model results in significant differences in the SLD compared to the linear cutting force model.


2010 ◽  
Vol 33 ◽  
pp. 356-362 ◽  
Author(s):  
Xionig Ying Pu ◽  
Wei Jun Liu ◽  
Ji Bin Zhao

A new cutting force model for peripheral milling is presented based-on a developed algorithm for instantaneous undeformed chip surface with NURBS. To decrease the number of the differential element, the contact cutting edges of end-milling cutter with the part and the chip thickness curve are represented by NURBS helix, and the instantaneous undeformed chip is constructed as a ruled surface with the two curves. The cutting force generated by the edge contact length and the uncut chip area. Using the cutting coefficients from Budak[1] , the cutting-force model verified by simulation. The simulation results indicate that new cutting-force model predict the cutting forces in peripheral milling accurately.


2000 ◽  
Author(s):  
Won-Soo Yun ◽  
Dong-Woo Cho

Abstract In this paper, a mechanistic model is first constructed to predict three-dimensional cutting forces, and the uncut chip thickness is calculated by following the movements of the position of the center of a cutter, which varies with the nominal feed, cutter deflection and runout. For general implementation to a real machining, this paper presents the method that determines constant cutting force coefficients, irrespective of the cutting conditions or cutter rotation angles. In addition, this study presents the approach which estimates runout-related parameters, the runout offset and its location angle, using only one measurement of cutting forces. For more accurate cutting force predictions, the size effect has to be considered in the cutting force model. In this paper, two approximate methods are suggested since the strict approach is practically impossible due to a measurement problem. The size effect is individually considered for narrow and wide cuts.


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