Dynamic modeling and error analysis of planar flexible multilink mechanism with clearance and spindle-bearing structure

摘要

To predict the dynamic precision of multilink high-speed precision presses (MLHSPPs), it is essential to develop a dynamic model of the multilink mechanism (MLM). Previous models only considered the effect of the clearance, flexible linkages and crank shaft, and often neglected the effect of supporting bearings' stiffness on the crank shaft system, which lowers the dynamic analysis accuracy of the MLM for MLHSPPs. In this work, based on both absolute nodal coordinate formulation (ANCF) and finite element method (FEM), an improved computational methodology for the modeling and simulation of a planar flexible MLM with clearance and spindle-bearing structure is presented considering the effect of clearance, flexibility of crankshaft and linkage, and bearing stiffness together, and its corresponding dynamic dimension chain between the slider and crank shaft is constructed. The elastic foundation model (EFM) and stick-slip friction model are used to describe the normal contact and tangential friction force between bushing and pin, respectively. It is demonstrated that the dynamic responses from the flexible model with clearance and spindle-bearing structure under no-load and blanking conditions agree better with the experimental data than those from traditional ones, and the effectiveness of the proposed methodology is proven. The existence of crankshaft-bearing structure aggravates the displacement deviation of slider and the motion of the pin center for revolute joint between lower slider and linkage was characterized by only one permanent contact state. Furthermore, the effect of the clearance size, the blanking force and the contact angle of the bearing on the dynamic responses and the corresponding deviation errors are also investigated. (C) 2018 Elsevier Ltd. All rights reserved.