Optimal workpiece positioning in flexible fixtures for thin-walled components

Abstract Flexible fixtures are finding widespread use in manufacturing processes of thin-walled components in the automotive and aerospace industries. Owing to its reconfigurability, a flexible fixture can take different layouts depending on the workpiece geometry and location. By finding the appropriate workpiece location, the deformation of workpieces under machining forces and their own weights can be reduced, hence increasing the quality of the final products. In this paper, we introduce a novel method for optimum workpiece positioning in rod type flexible fixtures for thin-walled components. First, the geometry of the workpiece is extracted from its CAD model. Second, a geometry-based method is proposed to find the optimal location of the workpiece relative to the fixture system. A composition of homogeneous transformations is performed to maximize the workpiece support capacity, initially place the workpiece in the fixture region, and maximize the number of active fixture elements (fixels). Third, the result is verified and visualized in a fixture verification module. An aircraft body panel is employed as an example to test the performance of the proposed method. Finally, conclusions and future studies are discussed.

[1]  Eric Haines,et al.  Point in Polygon Strategies , 1994, Graphics Gems.

[2]  Dongsheng Li,et al.  Process Planning and Simulation Strategies for Perimeter Milling of Thin-walled Flexible Parts Held by Reconfigurable Fixturing System , 2011, 2011 Third International Conference on Measuring Technology and Mechatronics Automation.

[3]  J. G. Tough,et al.  A method for characterizing polygons in terms of the principal axes , 1984 .

[4]  Giovanni Moroni,et al.  Robust design of a fixture configuration in the presence of form deviations , 2016 .

[5]  Y G Liao,et al.  A genetic algorithm-based fixture locating positions and clamping schemes optimization , 2003 .

[6]  Kenneth Y. Goldberg,et al.  A complete algorithm for designing planar fixtures using modular components , 1996, IEEE Trans. Robotics Autom..

[7]  Warren R. DeVries,et al.  Optimization Methods Applied to Selecting Support Positions in Fixture Design , 1991 .

[8]  Jianbin Xue,et al.  Deformation control through fixture layout design and clamping force optimization , 2008 .

[9]  Shreyes N. Melkote,et al.  Prediction of workpiece deformation in a fixture system using the finite element method , 2006 .

[10]  Yiming Rong,et al.  Development of a finite element analysis tool for fixture design integrity verification and optimisation , 2005 .

[11]  Zhou Kai,et al.  Multi-point location theory, method, and application for flexible tooling system in aircraft manufacturing , 2011 .

[12]  Kai Hormann,et al.  The point in polygon problem for arbitrary polygons , 2001, Comput. Geom..

[13]  John F. Canny,et al.  Planning for modular and hybrid fixtures , 1994, Proceedings of the 1994 IEEE International Conference on Robotics and Automation.

[14]  Hu Fuwen,et al.  Location Issues of Thin Shell Parts in the Reconfigurable Fixture for Trimming Operation , 2014 .

[15]  S. Jack Hu,et al.  A Variational Method of Robust Fixture Configuration Design for 3-D Workpieces , 1997 .

[16]  Yu Zheng,et al.  A geometric approach to automated fixture layout design , 2010, Comput. Aided Des..

[17]  Frank W. Liou,et al.  Fixture analysis under dynamic machining , 1997 .

[18]  Dinesh Manocha,et al.  Efficient simplex computation for fixture layout design , 2011, Comput. Aided Des..

[19]  Li Zheng,et al.  Optimization of the number and positions of fixture locators in the peripheral milling of a low-rigidity workpiece , 2007 .

[20]  Jingxia Yuan,et al.  Deformable Sheet Metal Fixturing: Principles, Algorithms, and Simulations , 1996 .

[21]  Z. M. Bi,et al.  Flexible fixture design and automation: Review, issues and future directions , 2001 .