Conceptual design and kinetostatic analysis of a modular parallel kinematic machine-based hybrid machine tool for large aeronautic components

Abstract

Abstract Precision manufacturing and intelligent assembly in the aeronautic industry pose new challenges for the design of Flexible Manufacturing Systems (FMSs). To address these issues, a modular Parallel Kinematic Machine (PKM)-based hybrid machine tool is proposed. The 5-axis hybrid machine tool is conceptually designed by integrating 3-Degree-Of-Freedom (DOF) over-constrained PKMs with a 2-DOF serial mechanism including a unique double-circumferential guideway. By integrating accessory devices, the proposed machine provides a promising alternative solution to building a novel FMS for the flexible manufacturing requirements of larger arc-shaped aeronautic components. A kinematic model is established to conduct an inverse kinematic analysis to predict the reachable workspace by using a ‘sliced partition’ searching algorithm. To evaluate the kinetostatic performance of the hybrid machine tool, a modified kinetostatic model is established by including the compliances of all joints and limb structures. The prediction accuracy of the proposed kinetostatic model is validated by numerical simulations. Two kinetostatic performance indexes, the average reaction index and the average displacement index, are formulated and applied to reveal the gravity-caused joint reactions and elastic displacement of the hybrid machine tool, respectively. The analyses show that the kinetostatic performances of the machine are heavily affected by gravity; thus, gravity must be considered during the early design stage. Notably, with minor revisions, the proposed kinetostatic model and performance indexes can be applied to other hybrid mechanical systems to efficiently evaluate their kinetostatic performances.