KINEMATIC SYNTHESIS OF THE GUIDE BEARING CENTRAL SLIDE-CRANK MECHANISM OF THE GRIPPING DEVICE BASED ON THE ENERGETIC MOTION TRANSMISSION INDEX

Abstract

Purpose. The main objective of the work is to perform a kinematic analysis and synthesis of the known schemes of guide bearing central slide-crank mechanisms by the criterion of the energy index of motion transmission with the restriction by the allowable pressure angles in the sliding pairs and the smallest deviation of the trajectory from straightness in the approximation area. The article is also aimed to determine the scheme that best suits the synthesis conditions and to propose the gripping device mechanism on its basis. Methodology. This purpose is achieved by means of analytical kinematics of flat mechanisms of the mechanism and machine theory and mathematical modeling of the positions and movement of links. Findings. The design of mechanisms with different gripping devices providing a constant clamping force of objects of various thicknesses with a constant drive power and minimal energy costs can be performed by the criterion energetic motion transfer index (EMTI). On its basis the analysis of the known straight-guiding central crank-slider mechanisms with an extended connecting rod is carried out according to the criterion of the smallest deviation from the EMTI unit. It was found that the practical use of main part of these mechanisms according to this criterion is extremely limited or impossible. Using optimized synthesis of kinematic equations, it was obtained the only values of the relative parameters and the rotation ranges of the driving crank for the guide bearing central slide-crank mechanisms with an extended connecting rod that best meet the optimization criterion and satisfy the restrictions for pressure angles. Based on the optimal parameters of the guide bearing central slide-crank mechanism a paired parallelogram eleven-link mechanism is proposed that provides the rectilinear movement of the gripping elements with a constant speed and constant clamping force which is equal to the nominal driving force of the drive. Originality. For the first time, a qualitative and quantitative analysis of the known schemes of the guide bearing central slide-crank mechanisms according to the criterion of the energetic motion transfer index was carried out and the optimal synthesis of the gripping device according to the results of the analysis was performed. Practical value. Practical recommendations are suggested for choosing a scheme, relative sizes and arrangement of links of the guide bearing central slide-crank mechanism of the gripping mechanism that corresponds to the requirements of the optimization criterion and restriction by the allowable pressure angles.

Keywords

• mechanical gripping device
• guiding mechanism
• energetic motion transfer index (emti)
• pressure angle