Method for determining reactions in pairs of single-moving mechanisms of a technological machine

Analysis of graphoanalytical and analytical methods for determining reactions in kinematic pairs of single-moving mechanisms has been carried out. The graphoanalytic method is characterized by clarity. Its application involves repeated reproduction of a number of actions. Analytical methods are based on the compilation of equilibrium equations for a single link or for a structural group of the mechanism. These methods are used, as a rule, to assess the effect of the useful resistance force and the change in the transmission angle on the values of reactions in pairs of single-moving mechanisms. In order to evaluate the effects of the gravity forces of the links and the variation of the transmission angle on the values of forces in pairs of a single-moving mechanism, a method for determining reactions in such pairs has been developed. The practical application of the method involves the synchronous use of AutoCAD and Mathcad programs. The difference between the method and the well-known graphoanalytic method is as follows. A polygon of forces is not constructed for the L.V. Assur structural group, angles are measured directly on this group. So, the angles between the lines of gravity of the connecting rod, rocker arm and the direction of the tangential components of the reactions in the crank-connecting rod and rocker-rack pairs are measured, respectively. In relation to the structural group of M. Z. Kolovsky, a triangle of forces is constructed and the value of the angle between the line of gravity of the crank and the direction of the full reaction in the crank-connecting rod pair is set. The total reactions in pairs of a single-moving mechanism are maximal in the position when the transmission angle is minimal. In this position of the mechanism, the crank continues the line of centers. The reaction in the connecting rod-rocker pair, unlike the forces in other pairs, increases both with an increase in the transmission angle and with its decrease.

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