Chatter Stability Prediction and Process Parameters’ Optimization of Milling Considering Uncertain Tool Information

Stability is the prerequisite of a milling operation, and it seriously depends on machining parameters and machine tool dynamics. Considering that the tool information, including the tool clamping length, feeding direction, and spatial position, has significant effects on machine tool dynamics, this paper presents an efficient method to predict the tool information dependent-milling stability. A generalized regression neural network (GRNN) is established to predict the limiting axial cutting depth, where the machining parameters and tool information are taken as input variables. Moreover, an optimization model is proposed based on the machining parameters and tool information to maximize the material removal rate (MRR), where the GRNN model is taken as the stability constraint. A particle swarm optimization (PSO) algorithm is introduced to solve the optimization model and provide an optimal configuration of the machining parameters and tool information. A case study has been developed to train a GRNN model and establish an optimization model of a real machine tool. Then, effects of the tool information on milling stability were discussed, and an origin-symmetric phenomenon was observed as the feeding direction varied. The accuracy of the solved optimal process parameters corresponding to the maximum MRR was validated through a milling test.

THEORETICAL RESEARCH OF THE TOOL WEAR INFLUENCE ON THE PARAMETERS OF THE DRILLING DYNAMIC SYSTEM

The quality of pre–drilling operations directly depends on the stability of the mechanical process. The paper examines the relationship between the ultimate tool wear and the vibration resistance of the system, which in turn depends on a number of the system's own parameters and the conditions of the cutting process. To establish these relationships, the scientific provisions of the theory of machine tool dynamics are used, and the analysis of processes in the dynamic system when drilling holes is carried out. An expression of wear is obtained, at which the dynamic system begins to lose stability.

Effect of Rack and Pinion Feed Drive Control Parameters on Machine Tool Dynamics

In large heavy-duty machine tool applications, the parametrization of the controller that is used for the positioning of the machine can affect the machine tool dynamics. The aim of this paper is to build a Multiple-Input and Multiple-Output model that couples the servo controller and machine tool dynamics to predict the frequency response function (FRF) at the cutting point. The model is experimentally implemented and validated in an electronically preloaded rack and pinion machine tool. In addition, the influence of each control parameter on the machine tool’s compliance is analysed.