Abstract:
Introduction. The article is devoted to the study of the synthesized concept of frictional contact of solids in crank presses. As a result of the analysis, the possibility of obtaining the maximum load characteristic of the friction contact within the interval of variation of the friction coefficient has been established. The possibility of equality of the values of the friction force of the friction contact at the boundaries of the indicated interval in the presence of a maximum and the achievement of their greatest stability under these conditions is also revealed. Materials and methods. When the angle value changes, the position of the maximum point changes. Since only the angle ratio establishes the equality of the friction forces at the boundaries of the interval of variation of the friction coefficient, changing the position of the maximum point of the function leads to a violation of this equality. In this case, the accuracy coefficient should be determined by the ratio of the maximum of the function to the smallest boundary value. To do this, it is necessary to establish trends in the change of the boundary values of the function associated with the variation of the angle. To solve this problem, a new value of the pressure tangent was presented as a product of the coefficient of variation and the base value of the tangent angle. The results of the study. The results show a high stability of the friction force during sliding of the friction contact bodies, although at large values of the pressure angle of the sensitive elements of the transducer sensor, the maximum friction force may briefly be proportional to the current value of the friction coefficient. Discussion and conclusions. As we see, the upgraded concept of frictional contact allows theoretically to obtain a very high stability of the friction force, however, due to the relatively large value of the angle and force parameter, it is used inefficiently. A necessary condition for the absence of vanishing of the output parameter of the main friction group of the friction contact in the interval of variation of the friction coefficient and the presence of the maximum function of the load capacity of the friction contact is the transfer of its full load by the sensitive elements of the additional friction group. An additional condition for the existence of a maximum is the need for the sensitive elements of the main friction group to transfer part of its full load with an equal number of friction pairs of both friction groups, and the sensitive elements to transfer the full load of the main friction group with less than the additional friction group number of friction pairs.
Keywords:crank press, friction coefficient, working mechanism, gain factor, overload, accuracy.
