Calculation on hydraulic cylinder driving force and jointforce for scissors lifting platform

HE Xuehong, YIN Qizhen, LU Wenjia, HU Zhiyong

(School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110819, China)

Abstract: Aiming at the problem that strength and stiffness of scissors lifting platform is checked, the principle of virtual work was used to obtain the driving force,and the whole model and discrete model were build to obtain the jointforce. Two ways based on principle of virtual work could be used for obtaining the driving force, they were called geometry and coordinate. The lifting platform with five scissors and two hydraulic cylinder was taken for example,whose expression of driving force was obtained with the two methods. Equilibrium equation was built to obtained the jointforce. The parameters were evaluated into the formula of driving force, driving forceFcurve along with change of lifting angleαwas drawed with Matlab, the two curves were compared with the curve obtained by testing in pratical engineering; The jointforce could be obtained by evaluating maximum of driving force and parameters into equilibrium equation. The results indicate that the error between of the two results is 2%; the error is within 5% between the theoretical value and the trial value, which verifies the correctness of method. The methods mentioned above can be applied to different scissors shifting platforms to obtain hydraulic cylinder driving and jointforce.

Key words: principle of virtual work; lifting platform; lifting angle; driving force;jointforce