报告题目：Minimum sequencing for multi-axis hybrid machining of complex geometries
报告人：Kai Tang (汤凯)，香港科技大学教授
With the development of new hybrid machining platform that incorporates both additive manufacturing and five-axis machining modules, it is conceivable that complex models that are previously impossible to manufacture with solely one of the two methods can now be produced. In order to successfully manufacture a complex structure, the additive and the subtractive process need to work alternatingly: to roughly stack a layer of material of certain height and then accurately machine it to the desired shape. Multiple alternations are needed to eventually produce a complex model. The planning of the build-up height in each alternation plays a crucial role in the overall process: a large build-up height may increase the chance that the partially constructed obstacle will block the cutter from accessing the in-process part; conversely, frequent alternations will degrade the overall efficiency and produce an inferior surface finish with dense marks. In order to find a perfect balance, a metric called “machinability” is proposed to evaluate the subtractive machining feasibility. An efficient algorithm for calculating the machinability under the dynamic obstacle growing environment is then developed accordingly. Based on that, an efficient and deterministic top-down sequential maximization algorithm is presented that strives to minimize the number of alternations while at the same time ensuring a smooth tool path for each subtractive operation. Ample computer simulation examples are given to illustrate the effectiveness of the proposed methodology.
Dr. Kai Tang received BSE in Mechanical Engineering from his hometown university the Nanjing Institute of Technology (now Southeast University) in 1982 and afterward, as sponsored by the Chinese government, went to the University of Michigan (Ann Arbor) where he received PhD in Computer Engineering in 1990. From 1991 to 2001, he worked as a software specialist at Schlumberger CAD/CAM (which in 1994 became Applicon and in 1999 became part of Unigraphics). Among his various responsibilities and projects, Dr.Kai Tang was one of the chief architects of the multi-axis NC surface machining software BravoNC; he also led a team that developed an ACIS-based geometric engine for 5-axis tool path computation. In 2000, he also for a short period of one year worked as the chief engineer in a start-up company focusing on voice recognition technology. In June 2001, he “went back” to school and joined the faculty of the Department of Mechanical and Aerospace Engineering at Hong Kong University of Science and Technology (HKUST), arising from Assistant professor in 2001, Associate professor in 2006, and Full professor in 2011. Dr. Kai Tang’s research interests are broad, but mostly concentrating on developing efficient and practical algorithms in CAD/CAM.Since joining HKUST in 2001, as sole PI he has obtained in total of HK$26 million in research funding from the Hong Kong RGC General Research Fund and Innovative Technology Fund. Aside from his regular professional research and teaching in academia, Dr. Kai Tang is also an avid writer.