A development method of cutting force coefficients in face milling process using parallelogram insert

This paper presents a modeling method of cutting force and a combination approach of theory and experimental methods in the determination of cutting force coefficients in the face milling process using a parallelogram insert. By the theoretical method, the cutting forces were modeled by a mathematical function of cutting cutter geometry (Cutter diameter, the number of inserts, the insert nose radius, insert cutting edge helix angle, etc.), cutting conditions (depth of cut, feed per flute, spindle speed, etc.), and cutting force coefficients (shear force coefficients, edge force coefficients). By the theoretical method, the average cutting forces in three directions (feed – x, normal – y, and axial – z) were modeled as the linear functions of feed per flute. By the experimental method, the average cutting forces in these three directions were also regressed as the linear functions of feed per flute with quite large determination coefficients (R2 were larger than 92 %). Then, the relationship of average cutting forces and feed per flute was used to determine all six cutting force coefficient components. The validation experiments were performed to verify the linear function of average cutting forces, to determine the cutting force coefficients, and to verify the cutting force models in the face milling process using a cutter with one parallelogram insert. The cutting force models were successfully verified by comparison of the shape and the values of predicted cutting forces and measured cutting forces. These proposed methods and models can be applied to determine the cutting force coefficients and predict the cutting force in the face milling process using a parallelogram insert and can be extended with other cutting types or other insert types

Heat generation and side milling stability of titanium alloy

In this paper, the thermal generation and milling stability of titanium alloy during machining are investigated mainly. A new definition of processing behavior is given based on the principles of minimization, entity expression and combination, and a model of side milling behavior is constructed. Through a series of side milling orthogonal experiments on Ti-6Al-4V titanium alloy, the cutting forces under different process parameters are obtained. Further, the cutting force coefficients of the model is calculated by the complete average algorithm and the peak average algorithm, and the milling stability of the system is analyzed by a stability lobe diagram. The results show that the different cutting parameters have important influences on the milling stability of titanium alloy.

Identification of Polynomial Cutting Coefficients for a Dual-Mechanism Ball-end Milling Force Model

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.

Study of Effect of Teeth Number on Cutting Force for Cutter Selection in the End Milling of TC4

Cutting force is a very important factor in machining processes for predicting chatter, surface roughness and machining efficiency. For a given cutter, cutting force is determined by cutting force coefficients and uncut chip thickness. Once a new cutter is adopted, repeated experiments are carried out to calibrate its cutting force coefficients. To reduce the high cost and longtime experiments, theoretical analysis of the effect of cutter parameters on cutting force is required. In current literatures, some cutter parameters, such as helix angle and pitch angle, have been studied to explore their effects on cutting force. However, there is little research about the effect of teeth number on the cutting force. To fill up this gap, the effect of teeth number on cutting force is studied in the paper. Firstly, it is derived and experimentally verified that the cutting force coefficients are unchanged for cutters with different teeth number but the same teeth parameters, e.g., rake angle, shear angle, etc. Secondly, by matching the measured cutting force point with the cutter rotation angle, the cutting force coefficients can be calibrated by only one experiment when we assume that the material of the cutter is the same. Therefore, the cutting forces generated by cutters with different teeth numbers can be predicted based on only one experiment. Thirdly, from the various comparisons, it is concluded that cutter with 2 teeth number is suggested for side milling and cutter with 3 teeth number is suggested for slotting when surface roughness is considered. The cutter with 5 teeth number is suggested when only the machining efficiency is concerned. Finally, various experiments are carried out to verify the proposed study in milling of titanium alloy Ti6Al4V (TC4), and the comparison results show a good agreement.