Time efficient and energy saving five-axis machining of complex surface

Abstract

When processing complex parts such as turbine blades and dies on five-axis machine, the total spent time as well as the energy consumption can be extremely large. Owing to the physical constraints of cutting force and kinematic limit of the machine, time and energy efficiencies are the two critical issues in five-axis machining. Given a freeform surface and a specific machine configuration, the primary objective in this thesis research is to devise a five-axis machining operation aiming at improving the machining time and energy efficiency, which is particularly pertinent for today’s environment-conscientious atmosphere. To achieve this goal, a general five-axis machining process has been separated into five sequential stages. The modifiable tool path generation and workpiece setup in the first two stages exert significant impacts on the final execution of the machine. Bearing this in mind, we proposed two independent optimization strategies to carry out time-efficient and energy-saving five-axis machining without sacrificing the specified surface finishing accuracy. In the first proposed tool path planning strategy, two potential fields that identify the time and energy efficiency have been respectively derived, which for an arbitrary point on an arbitrary freeform surface identify the principal direction achieving the best efficiency in machining time or energy consumption. An iso-scallop height based tool path optimization scheme is then developed to accommodate the potential field. Compared with popular strategies in academia and industry, the remarkable more than 25% savings in terms of total machining time and total energy consumption have been accomplished in our preliminary experiments. With the tool path generated, our second strategy strives to further minimize the total machining time and energy cost by optimizing the workpiece setup. The way how a workpiece is setup on the working table inevitably affects the machine’s kinematic performance, which dominates the overall processing time and energy consumption. By exploring geometric characteristics of a specific five-axis machine configuration, a geometry based algorithm is designed to find the optimal setup parameters. The experiments performed by us, in both computer simulation and physical cutting, have validated that the optimized workpiece setup can achieve as high as 50% savings in both energy cost and machining time, when compared with a conventional one, both using the same tool path.

Date of Award	2016
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology