Advanced Engineering Research (Dec 2019)
Increasing stable operation of the working body in crank presses
Abstract
Introduction. Static and dynamic loading systems of the safety friction clutch (SFC) are investigated. A schematic diagram of the frictional contact of solids in the forging and stamping machines is synthesized. From the point of view of increasing the operational stability of the working body in crank presses, the following factors are considered: response time, current friction factor and a change in torque under static and dynamic loading of the safety clutch.Materials and Methods. The response time of the SFC with differentiated friction pairs is determined. The sought indicator corresponds to the period of the uptime in which the load is amplified (between values of the rated torque and the response time). The parameters of a dual-mass system correspond to the parameters of an equivalent system that includes a clutch and key parts of the drive. The system elements include mass of inertia; mass of inertia including the engine rotor and the main (driving) part of the SFC; elastic connection with the specified value of the reduced angular stiffness. Research Results. Values of the load arising in elastic bonds not conditioned by the working body operation are specified. Formulas that should be used to determine the values of the driving moment and generalized coordinates are presented. Start conditions with an increase in the load value from the initial indicators are described. Discussion and Conclusions. The dependence is found for calculating the minimum number of friction pairs of the basic friction group. It is shown that at this minimum, the gain used to implement an “ideal” SFC load characteristic, does not exceed the maximum permissible value, even if the value of the friction coefficient is maximum. A fundamental SFC model is presented, in which, with a minimum value of the friction coefficient, negative feedback does not work. In the functional diagram of the basic SFC version modernization, there is no negative feedback with a minimum value of the friction coefficient in order to increase the accuracy of operation and the rated load capacity.
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