JUSTIFICATION OF KINEMATIC AND POWER PARAMETERS OF THE STAR-SHAPED SPRING OF FLEXIBLE OVERLOAD COUPLING

Various mechanical couplings are widely used in drives of building, road, land reclamation machines, etc. The main purpose of coupling is to connect two coaxial shafts and transmit torque between them. In addition to the mentioned, flexible overload couplings perform following responsible functions: compensation of detrimental effect of shaft geometric axes offset; amortization of vibrations, jolts and shocks; parts overload protection; the machine start-up facilitation. Various operational functions contributed to the development of a large number of such coupling construction. But in all cases there are still many shortcomings in the coupling operation that need to be eliminated by its improvement. The modern technical literature describes overload jaw couplings with a shear pin and others that rigidly transmit torque through direct hubs contact that negatively affects the performance of elements of drive and the machine in general. Based on the analysis of the designs shortcomings of known coupling we developed new designs of overload flexible couplings with star-shaped springs The article examines the structure of an overload flexible coupling that contains internal and external hubs, connected by a star-shaped spring with the parabolic edges inserted in grooves on the outer surface of internal hub and inner surface of the external hub. Position of the star-shaped spring is fixed on the inner hub by retaining ring. The interior space of coupling is conserved with the cover that is attached to hub by screws and designed to protect the star-shaped springs from the external factors influence and for its lubrication. The working principle of coupling is described as follows. During the rotation of inner hub, torque is transferred to the outer hub through star-shaped spring and grooves. In overloading mode, star-shaped spring starts deforming, decreasing in diameter along its outline, with grooves being compressed, within the elastic deformation range, and slipping out of the external hub grooves, which curves radius is larger than one of spring edges, and sliding on the surface of an external hub until torque is over the nominal value. We have conducted a preliminary analysis of kinematic and power parameters of overload couplings that are carried out through star-shaped spring. It is assumed that starspeech springs is a two-hinge arch in the form of a square parabola and using the methods of structural mechanics, in particular, numerical integration by Simpson’s formula, we have conducted calculations. Analytical expressions obtained allow drawing conclusions about workability of the star-shaped spring of flexible overload coupling during the torque transmission.