Kinematic Synthesis of Crank-Slider Mechanism of the Gripping Device Based on the Power Transmission Index

Abstract

Purpose. The main purpose of the work is to carry out a kinematic synthesis of a crank-slider gripping device in accordance to the criterion of the constancy of the drive power of the mechanism with restrictions on permissible pressure angles in kinematic pairs. Methodology. Achieving this purpose is carried out by means of the theory of mechanisms and machines using the analytical method of the Ozols triangles of kinematics of plane rod mechanisms and mathematical modeling of the movement of links. Findings. The ten-bar mechanism of the gripping device is built on the basis of a paired parallelogram of a crank-slider mechanism with a leading slider. For gripping device, which is built on the basis of the rod scheme, it is advisable optimal design using the criteria for the transfer of motion or transmission indices. The criterion of optimization is the ratio of the speed of the leading link to the projection of the velocity vector of the driven point on the direction of the clamping force vector (power transmission index). The lowest energy costs can be achieved, provided that this ratio is equal to one. Analytical dependences are obtained for determining the velocity function of the central and de-axial crank-slider gripping device, which are convenient for analysis and modeling. On their basis, an energy synthesis of the geometrical parameters of the mechanism of the gripping device in accordance with the criterion of the smallest deviation from the unit ofpower transmission index is performed. The possibilities of the gripping device are enhanced by using it in a de-axial crank-slider mechanism, and the best results can be obtained in a scheme where the de-axial value is larger than the crank length. It is determined the specific values of the relative parameters of the lengths of the links and the ranges of rotation of the crank of the central and de-axial crank-slider of the grippingdevice, which best meet the optimization criterion and satisfy the pressure angle constraints. Originality. For the first time, a new criterion for the transmission of motion was introduced –power transmission index. According to this criteria, a kinematic synthesis of the gripping device built on the basis of a paired crank slider mechanism was carried out. Practical value. Practical recommendations are proposed on the size and location of the links of the mechanism for the central and de-axial crank-slider mechanism, which satisfy the requirements of the optimization criterion and implement restrictions on permissible pressure angles.