| The precision manufacturing and intelligent assembling of aeronautic structural component have posed a new challenge for the development of flexible manufacturing system.In order to realize efficient manufacturing and quick assembling of the arc-shaped aeronautic structural component with large scale,this paper proposes a hybrid flexible manufacturing system consisting of a C-type guideway and two parallel kinematic machine(PKM)module.Firstly,the conceptual design of lockable spherical joints(labeled as LSJ),modularized limb and the reconfigurable PKM module are carried out with the virtual prototype technology.Two types of LSJ-I and-II are designed,six types of joint modules are achieved,moreover,nine types of modularized limbs can be presented.Based on the variations of PKM,four types of Exechon-like reconfigurable PKM modular can be designed.By integrating the Exechon-like PKM moduler to a serial moduler with C-type guideway,the hybrid manufacturing system can be constructed.Secondly,the screw system of the Exechon-like PKMs can be formulated with the screw theory.Based on this,overfull Jacobian matrix J of the PKMs can be derived.The analysis indicates that the above four types of LSJ-based PKMs both possess two rotational and one translational(2R1T)motion capabilities;and there is no constraint singularity for the proposed PKMs within its workspace while conditional architecture singularity.In addition,a kinematic model of the proposed system is established to conduct the parasitic motions and inverse kinematic analysis.Based on this,a ‘sliced partition' algorithm is proposed to predict the reachable workspace of the hybrid system equipped with Exechon and Exe-Variant PKMs.Thirdly,utilizing the force analysis and elastic deformation analysis,a kinetostatic model of the Exechon-like PKMs is developed to calculate the static stiffness,gravity-caused elastic displacements and joint reactions of the PKMs.The results imply that the kinetostatic performance values are axisymmetrically distributed over the given work plane due to the symmetric structural features of the PKMs.In addition,the kinetostatic performance mappings of the proposed PKMs are more strongly position-dependent with the configuration angle ? and ? while less affected by the distance between the platform and the base(limb length),and the effects of the configuration angle ? on the kinetostatic performances of the PKMs are not unified.Finally,two laboratory prototypes are built by the 3D printing technology and corresponding motion control system.The kinematic experiment of the PKM with2UPR&1RPS topology is carried out to manifest that the designed PKM moduler possesses 2R1 T motion capabilities and desired mobility in the workspace.The experimental values are in good agreement with the theoretical values,which verify the proposed kinematic model.In addition,a numerical model for the systems is developed in ANSYS Workbench to show that the calculation errors between the analytical results and the numerical simulations are very close.Based on this,the average displacement index and average reaction index are proposed to conduct the mapping relationships between system's kinetostatic performance and configuration angle ?.The hybrid manufacturing system proposed in this paper claims the merits of a large workspace generated by the C-type serial mechanism and high rigidity and coming from the PKM module,providing a potential alternative solution for the flexible manufacturing of aeronautic structural components.It is worthy mentioning that the achievements concluded in this paper,such as conceptual design,kinematic analysis and kinetostatic analysis of the hybrid manufacturing system,also can be of great significance for the design,analysis and performance evaluation of the other parallel/hybrid machine systems. |
PDF Full Text Request