Analysis of schemes of workpiece gripping

Nowadays, the developments are very essential, which allow to replace the human work by automation means. Devices, their properties and features, investigated here, are capable to lighten the human work, secure it and release human resources. This paper presents the investigation results of fixation and transportation of objects by a three finger-action gripping device (GD) from the point of view of the efficiency and reliability of these processes. Analysis showed, that the efficiency of the workpiece gripping depends on many parameters: the material, requirements to the surface quality of the gripped element, surface and material quality of gripping jaws, number of phalanxes of gripping fingers and some other. Two types of workpieces to be gripped have been subjected to the analysis: prismatic and spherical. They have been chosen not randomly, because the majority of shapes of blanks and workpieces can be somehow approximated to these two considered types. When considering the fixation and transportation of the prism, a special attention is paid to the geometry of a gripping scheme. The influence of separate parameters of a gripper on the quality of fixation and efficiency of the gripping scheme has been discovered. Methods of eliminating the possible problems on the quality and reliability of gripping have been proposed. When analyzing the gripping of a spherical object, a great attention has been paid to the gripping efficiency and force analysis. According to the requirement of the least forces for fixation and transportation of the object, these or those parameters of the gripper have been determined: length of phalanxes and separate links, their geometry, force conditions. In the course of the present investigation, various types of gripper layouts and gripping schemes have been analyzed, advantages and drawbacks of each scheme compared with other ones have been discovered. Mathematical and force calculations have been performed. It is noted in the conclusion, that in order to choose an optimal scheme and layout of a gripping device, the following criteria are determinative: purpose of the gripper; environment and conditions of operation; requirements to the positioning accuracy; account of characteristics of the workpiece material and its surface.