Shaft-hub joint for transmission of torque between two equiaxial machine parts

#The invention concerns a shaft-hub joint for transmission of torques between two equiaxial machine parts.

#It is known that in power trains, for example such for use in rolling mills where the torque generated by the motor is transmitted via shaft trains--in a rolling mill, e.g., the working roll is powered through a jointed shaft--disturbances on the machine end being driven due to which a transmission of torque from the power input to the power output may be interrupted at continued operation of the power source cause a deformation in the power train, due to torsion, and eventual torsional fracture. The torsional fracture shows in the extreme case a fracture pattern of 45.degree. to the axis of torsion, due to the tensile stresses occurring in twisting. In the case of the rolling mill, for example, torque transmission between the power source and working roll is interrupted in the case of working roll jamming. Subsequent to the fracture, i.e., in the example after separation of the working roll from the power source and with simultaneous continued operation of the power source, the fracture face on the side of the drive train that is still joined to the power source is twisted relative to the now stationary fracture face located on the side of the working roll. Due to the superimposition of the fracture faces and due to the differences in inertia and speed of rotation between the parts of the power train that have been created by the fracture--the one connected to the power source and that joined to the working roll--the part joined to the power source undergoes an axial shift in its own direction. The continued drive motion imparted by the motor and the obliquely fashioned fracture lead generally to the occurrence of high axial forces which bring about a positional shift of individual elements of the power train, in the extreme case a heaving of the components out of their anchoring.

#A known solution for avoidance of such incidents consists in fashioning the joint between power source and element being driven, not integrally in the form of a shaft train, but in at least in two parts, and to join these two parts in such a way that the torque transmission will be realized while also appropriate overload relief mechanisms are allowed to become effective which at high axial forces interrupt the transmission of torque. In the prior solutions, an element is used as a safety clutch which also functions as the rotationally fixed joint between the two parts, for example the two parts of the shaft train. The safety clutch serves the transmission of high torques and is provided with a system for torque limitation, such as is known for instance from DE 29 23 902.

#The solution to the problem according to the invention will be illustrated hereafter with the aid of the figures, which in detail show the following:

#FIG. 1 illustrates schematically the basic principle of a positive-locking overload relief mechanism against axial overload with the simultaneous option of transmitting high torques;

#FIG. 2 shows schematically another embodiment of an inventional arrangement for safeguarding against axial force overloads;

#FIG. 1 shows a shaft-hub joint 1 for transmission of torques between the equiaxial machine parts--a first machine part 2 and a second machine part 3--and for realization of axial length equalization. To that end, the shaft-hub joint 1 is fashioned here as a spline joint with sliding fit. The additional arrangement of an overload relief mechanism 4 allows the axial movability within the shaft-hub joint 1 only at a specific magnitude of axial force.

#The overload relief mechanism 4 is comprised of at least one interlocking unit 5 installed in one of the two machine parts, presently in the first machine part 2. The interlocking unit is composed of an interlocking element 6 and, in the simplest case, a spring 7 and a stop 8 that limits the possible prestress force of the spring 7 while forming a structural unit with the interlocking element 6. The spring 7 forces said interlocking element 6 into a mating receiving recess or groove 9 on the second machine element, thus entering with it into a positive-locking joint. The latter serves to absorb axially directed forces; peripheral forces are not transmitted thereby. Recess 9 can be an annular groove, an elongate or short groove or a recess matching the contour of element 6. In all cases the recess is bevelled when viewed in cross-section.

#The number of interlocking elements 6 engaging the machine part 3 on its periphery 10 and the adjusted prestress of the springs 7 determine the magnitude of the axial forces that causes the elimination of the positive locking, that is, the components of the axial force counteracting the prestress force of the spring(s) and leading to the elimination of the frictional engagement, always depending on the bevel angle.