Repeated Connections in the Schemes of Link Slider-Crank Mechanism of Gripping Device

Abstract

The article is aimed to carry out a structural analysis of gripping device as a mechanism with a variable structure and external unilateral constraints, as well as to determine the number of repeated connections in the internal and external contours in the mechanism diagram, and to recommend the ways to reduce them. Methodology. Solution of the set problem is realized by means of the mechanisms and machines theory using the universal structural theory of Ozols for analyzing the gripping device as a mechanism with internal and external constraints. Findings. The design of schemes of mechanical gripping devices rarely provides for a stage of structural analysis and synthesis of the mechanism. The preference is given to mandatory kinematic and kinetostatic calculations, layout and design. If structural analysis is carried out, then most often it is limited to calculating the number of the mechanism freedom degrees. The ten-link gripping device is built on the basis of coupled parallelogram slider-crank mechanism with a leading slider. The leading slider acts on the connecting rods connected by the rocker with the frame. The connecting rods bear the clamping elements of the gripping device. The added dyads form a parallelogram and provide a plane-parallel movement of the gripping elements of clamp. Structural analysis was performed using structural schemes for two states of the mechanism: before clamping the object and in the state of the clamped object. The main internal structural parameters of the kinematic scheme: the number of links-10, the number of connections-13, the number of contours-4, the mobility-1, the number of internal repeated connections-11. The number of external connections-12, the actual mobility of the mechanism-1, the working mobility of the mechanism is-0, the number of lost mobilities of the external body from the action of external connections-6, the number of external repeated connections-5. Originality. Structural analysis of the coupled slider crank mechanism of the gripping device as a mechanism of a variable structure with internal and external connections is carried out for the first time. It is performed contour search, analysis and elimination of useless repeated connections in the internal and external contours of the mechanism. Practical value. Practical recommendations for changing the mobility of kinematic pairs are proposed to reduce the number of repeated connections in internal contours and to provide unloading connection in the outer contour of the mechanism.