Research On CAD/CAM Technology For Closed Surface Fiber Placement

Automatic fiber placement is an important manufacturing technique to fabricatecomplex composite parts, which are widely applied in aviation and aerospace industriesin recent years. Research on automatic fiber placement focuses on three aspects, whichare the hardware equipment, materials technology and CAD/CAM technology. Amongthem, CAD/CAM technology as one of the key technologies for automatic placement ofthe composite could improve the material utilization, reduce design errors, optimize theplacement process and reduce production costs and cycle. Closed surface parts accountsfor a large proportion of composite structures in the aviation and aerospace. So theresearch of its CAD/CAM technology has important theoretical significance andpractical value.Firstly, the characteristics of the fiber placement technology to manufacture partswas analyzed and the framework and function of the CAD/CAM systems wasdetermined in this paper. The principle of modular design was used to facilitate theexpansion and improvement of the follow-up functions. In order to compatible with theenterprises’ CAD/CAM systems, the CATIA Component Application Architecture (CAA)was adopted as the system development platform.Secondly, the iterative method was used to obtain the information of a path forcomplex closed surface which could not be expressed by analytic formula (e.g. S-shaped inlet). Algorithm of path planning for0°,±45°and90°ply was studied,including the determination of the baseline, iterative method of the placement curve,calculation of the variable step and plane curvature; compared the pros and cons ofvariable step and fixed step; researched the planning methods of offset feature points tosolve the path and the tow edge line alternately; studied the calculation methods offibers amount for0°,±45°ply which the maximum fiber number in a tow is even orodd number and analyzed the fiber coverage area.Thirdly, post-processing algorithm for fiber placement machine which developedby the Harbin Institute of Technology was studied by applying D-H method. Areasonable motion control amount of each axis was got by the establishment ofcoordinate transformation matrix, the derivation of the inverse kinematics equations andconsidering the motion range of each axis. In order to avoid the problem of redundantrobot kinematics, motion control information was divided into the spindle control andthe manipulator control to be solved. The rotation direction and angle increment of thespindle was researched. Finally, the operator interface for the fiber placement CAD/CAM system wasachieved and the above algorithm of path planning, post-processing and capability ofmotion simulation were integrated into the system. In this paper, whether the fiberplacement paths and motion could be implemented by practical fiber placementmachine, is analyzed and verified through three criteria in the simulation system. Thecorrectness of the post-processing algorithm was verified by motion simulation.