A synthetical stability method for cutting parameter optimization to assure surface location accuracy in flexible part milling

Abstract

Flexible parts are widely used in the aeronautic and power industries which have high machining accuracy requirement. However, the flexible part is apt to vibrate in cutting processes due to its low structure stiffness and damping. Accurate approximation of cutting stability boundary of flexible part is difficult, because traditional stability analysis simplifies the complex dynamic system and some parameters still have large vibrations and can cause bad surface accuracy even when they are predicted to be located in the stable zone. To better evaluate the stability in flexible part milling, a synthetical stability method is proposed to calculate the boundary which can assure both the cutting stability and the surface location accuracy. To exclude other factors which may have great effect on cutting stability, such as multiple structure modes and structure mode coupling, etc, a flexible support platform is designed to test the validity of the classical local stability analysis. After the comparison between the local stability prediction and the experimental results, it is found that the local stability analysis is defective for the stability prediction of the flexible part milling. Therefore, the dynamical equation is improved and both the periodical excitation and the regenerative excitation are considered. The stability boundary is calculated by using the time-domain numerical method, with the radial immersion and cutting entrance angle's variation originated from forced vibration being considered. The simulation based on the synthetical stability analysis has a good agreement with the experimental results, which verifies the validity of the presented method.

Prediction of chatter stability in high speed milling using the numerical differentiation method

“…Combine Eqs. (9) and (23), and the state transition relationship on a tooth passing period interval can be formulated as follows: …”

“…In the early days, the time domain methods [6][7][8] are used for the simulations of chatter vibration in the cutting process, and they are quite suitable for complex situations, such as in the case of thin-walled part milling [9] and variable pitch end milling [10]. To improve the computation accuracy and efficiency of stability, much effort has been devoted to acquire the stability lobe diagrams analytically or semi-analytically.…”

Multi-Objective Machining Parameters Optimization for Chatter-Free Milling Process Considering Material Removal Rate and Surface Location Error

“…For instance, Schmitz's team proposed methods to predict the SLE in time and frequency domain, and pointed out that the SLE was dependent on the machining parameters [21], [22]. As the SLE determines the geometric accuracy of the workpiece, it should be discussed in the machining parameters optimization [23]. Zhang et al [24] had emphasized uncertain parameters in milling process and established a formulation for obtaining the robust minimum SLE and maximum spindle speed.…”

Stability prediction of thin-walled workpiece made of Al7075 in milling based on shifted Chebyshev polynomials

“…Thevenot et al [33] reported a three dimension lobes construction method and applied it to thin-walled structure milling. Zhang et al [34] proposed a synthetical stability analysis method for flexible part milling, in this method the regenerative dynamic excitation and steady periodical excitation are simultaneously considered.…”