Dynamics modeling and analysis on boom system of wet spraying machine
HU Shi-cheng1,2,3, SONG Jing-jing1,2, WANG Xiang-jun3
1. College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China;
2. State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, China;
3. China Railway Wuxin Group, Changsha 410100, China
Abstract In view of the problem in explicitly calculating the driving force of hydraulic cylinders accurately in the boom system of a wet spraying machine, the dynamics model of the boom system was established by using the method of analytic geometry and Lagrange equation. An equivalent driving cylinder was established as a twobar linkage mechanism including a cylinder rod and a sleeve which were in rectilinear motion relatively. Thus the boom became a multilink mechanism that was an incompleteopenedchain. Using the method of analytic geometry, a functional relation between boom bars' rotation angles and hydraulic cylinders' stroke was deduced as the kinematic model of the boom system. On the basis of kinematics and Lagrange's dynamical equations, the mathematical model related generalized forces (driving force of hydraulic cylinders) to generalized coordinates (cylinder stroke) was established. A typical working process of the wet spraying machine was selected to analysis. The analytic expressions of the generalized forces were solved by using the software of MAPLE. Then the expressions were imported into MATLAB to carry out numerical solutions. At the same time, the boom system was analyzed by using the tool of Pro/E mechanism dynamics. It contrastively showed that the simulation results of MATLAB were approximately in conformity with the PRO/E's, which verified the validity of the dynamics model of the boom system. Finally, the influence on maximum driving force of driving cylinder on a typical condition by change of position of the cylinder pivot point was analyzed and the results showed the original structure of boom system should be optimized. Thus, the dynamical model provides a theoretical basis for selecting the type of cylinders and optimization on the actuator force of driving cylinders.
HU Shi-cheng, SONG Jing-jing, WANG Xiang-jun. Dynamics modeling and analysis on boom system of wet spraying machine. Chinese Journal of Engineering Design, 2014, 21(3): 227-234.