The process of increasing the stable operation of the working body in crank presses

. The article considers 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. As result 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 zero reversal 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 at an equal number of friction pairs of both friction groups, and for the sensitive elements to transfer the full load of the main friction group at a lower number of friction pairs than in the additional friction group.


Introduction
This article investigated the static and dynamic loading system of the safety friction clutch and synthesized the schematic diagram of the friction contact of solids in forging and stamping machines. As a result of the analysis the possibility of obtaining a maximum load characteristic within the interval of change in the coefficient of friction is established. The possibility of equality of the friction force values at the boundaries of the specified interval in the presence of a maximum and achieving their greatest stability under these conditions is also revealed. The results show a high stability of the friction force during slippage of bodies, although at large values of the pressure angle of the sensitive elements of the sensor-transducer, the maximum friction force can be briefly proportional to the current value of the friction coefficient [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15].

Materials and methods
There is a need to conduct research to find time of operation of a safety clutch (PFM) that has a differential pair of friction which are corresponding to the area of working time, which in the loading process increases from the value of the nominal torque н T to the value of the actuation torque i T . The system that are consisting of two masses corresponds to the equivalent system in its parameters, which has a clutch and key parts of the drive indicated in Fig.1. We establish that the damping value in the current system and in the PFM is low and it should not be used, and the value of the reduced moment of the resistance forces is equal TH, we obtain the equations of motion [1]: which believes that by values of variables 1 c are smaller than the value of the variable calculated by (6), the value of the left part in (7) is much larger than the right part [6][7][8]. As a result of the search coefficient values for these trigonometric functions in equation (3), with a possible decrease in S1 the amplitude of the oscillations increases, that we study by , and the value of the amplitude of oscillations The length of time for which the value of the elastic coupling moment 3 is identical п Where n =0, 1, 2,…., n . At the value of expression (9), the last presented equation changes into an expression of type: For hard of PFM Here the value of angular stiffness PFM is equal to: The value of the found expression is obtained in the form of an analytical total: -safety friction clutch-hard type

Result of this is
As a result of the conducted researches it is necessary to specify: as the value increases 2 с the value of the moment which are occurring at the elastic of 4 (indicated by flexible coupling) reduces; with increasing 2 с the torque 2 T  (indicated the hard clutch) increases.
We performed a study of the types of drive load, where before actuation of the safety clutch overload value is not the cause of stopping the working bodies of the machine. In this regard, the scheme is presented in Fig.2. We presented the equations for this system in the following form The value of the torque size Tc depends on the type of process machine and the possibilities of its application, and is indicated as (1,2...4) TH [10][11][12][13]. We established that the working body has a power reserve, and the value of the angular velocity of the masses of inertia 1 is assumed to be unchanged, i.e.
As a result (16) we got [13]: We had to perform the summation operation as: Result of the summation operation of equations (15) and (16): We need to differentiate this twice (16): If we substitute the last expression into equation (16), we will obtain: From (20) we will find: If we differentiate the expression (21) twice, we will obtain:

Discussion and conclusions
As you can see, the upgraded circuit diagram theoretically allows to obtain a very high stability of the friction force, but due to the relatively large value of the parameter  tg , the force п F is used inefficiently. A necessary condition for the absence of zero reversal of the output parameter in the interval of change of the coefficient of friction and the presence of a maximum of the load capacity function is the transfer of its full load by the sensing elements. An additional condition for the existence of the maximum is the need to transfer the sensing elements of its full load at an equal number of friction pairs of both friction groups, and transfer the sensing elements of the full load of the main friction group at a lower number of friction pairs than in the additional friction group.