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- Autors
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Pohrebniak R. P.
- Issue
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Hoisting and transport equipment, 2023, №1(68)
- Pages
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56-70
- DOI
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10.15276/pidtt.1.68.2023.05
- Abstract
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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 energy index of motion transfer (EIMT). 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 one EIMT. 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 leading crank for the straight-guiding central crank-slider mechanism 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 straight-guiding central crank-slider 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.
Practical recommendations are suggested for choosing a scheme, relative sizes and arrangement of links of the straight-guiding central crank-slider mechanism of the gripping mechanism that corresponds to the requirements of the optimization criterion and limits of the permissible pressure angles.
Structural analysis of the coupled crank-slider mechanism of the gripping device as a mechanism of a variable structure with internal and external connections. It is performed contour analysis, search and elimination of useless repeated connections in the internal and external contour of the mechanism. Reduced number of harmful repetitive connections in the external contour of the mechanism. Practical recommendations have been developed on changing the mobilities of kinematic pairs to eliminate all repeated connections in the internal contours of the mechanism. To reduce the number of harmful repeated connections, the introduction of a self-aligning unloading connection into the external contour of the mechanism is proposed.
- Keywords
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mechanical gripping device; guiding mechanism; energy index of motion transfer; pressure angle; mobility of mechanism; repeated connections; external connections
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