Systematic errors identification in the structure of CNC machines due to elastic deformations

摘要

Highly accurate and precise CNC machines are always required in modern manufacturing systems. Among them, the multi-axis milling machines which possess the X-Y-Z linear and A-B rotary motions plays a significant role in the aerospace industry. Geometric, cutting force and thermal errors are three main sources of error which affects the accuracy of CNC milling machines. This article presents a new methodology to identify systematic errors introduced due to the elastic deformations in the structure of CNC milling machines. Under maximum speed and feed, the theoretically measured thrust and torque for actual conditions is applied to identify the systematic errors in a real time drilling process. An FEM model is developed to predict the elastic deformations based on thrust force, material properties and actual operating conditions. The simulated systematic errors are validated through experimentation on a specially designed work piece. The identified systematic errors can compensated to achieve higher accuracy of milling machines. The results of this study are useful in CNC machining of aerostructures in particular.