Kinematic analysis of parallel transfer mechanism

Abstract

The parallel transfer mechanism (patent LV 15506B) consists of links in form of two parallelograms with one common horizontal link and parallel to it opposite links of equal length, and the links of side edges of the parallelograms the lengths of which are equal in pairs, respectively. The common link of the parallelograms is formed as a guide for a slider to which two links are connected corresponding to the lengths of the side edge links of the parallelograms. The other ends of these elements are connected to the side edge links forming a rhomboid contour. The links of this planar linkage are connected by pin joints. For cyclic operation of the parallel transfer mechanism the hydraulic actuator is connected to the slider and attached to the common link. If the lower parallelogram link is the ground link, the output link will be the upper link, which parallel transfer movement will be ensured. The purpose of the work is kinematic analysis of this innovative mechanism. The side members with a length of 0.5 m and a hydraulic actuator with a speed 0.2 m·s-1 of movement are selected as a sample of the mechanism. Kinematic parameters as displacement, velocity and acceleration of the upper output link were determined using the Mathcad program for an idealized mechanism ignoring friction. These maximum values were 1 m, 0.985 m·s-1 and 0.508 m·s-2 accordingly. If the displacement of the output link is reduced, avoiding singularities and ensuring stability of mechanism, the maximum displacement, velocity and acceleration values will be reduced to 0.65 m, 0.55 m·s-1 and 0.10 m·s-2, accordingly. By changing the input parameters, it is possible using this Mathcad calculation method to obtain the values of the kinematic parameters for other size mechanisms.