GB1423630A - Arrangements for the generation of vibrations for testint torsional vibration behaviour - Google Patents

Abstract

1423630 Torsion testing ELBE-WERK ROSSLAU VEB 5 June 1973 [20 July 1972] 26752/73 Heading G1S [Also in Division H2] An arrangement for the generation of vibrations for testing the torsional vibration behaviour of parts comprises a rotatable shaft having at an end thereof means for carrying a part to be subjected to torsional vibration, the shaft being driven by the rotor of an electric motor, an element connected to the shaft to produce a constant load torque on the motor and an exciter unit to electrically load the rotor in a time-variable manner to cause rotor load torque variations about a mean value set by the element, the variations resulting in a torsional vibration imposed on the rotary motion of the rotor and the part-carrying means. The motor may be a series-wound, shunt-wound or squirrel-cage motor or, as shown in the Figure, a slip-ring induction motor 4 having at its shaft end 7 an induction brake 3 to produce the constant load torque and at its shaft end 7' a shaft part 1 having a mounting flange 6 to receive parts (not shown) to be tested for their behaviour under torsional vibration. The ends 7, 7' are mounted by bearings in pendulum fashion, whereby the motor stator can swing as a unit about its central axis which is also the axis of the motor rotor. The stator winding is connected to A.C. mains voltage or to an adjustable A.C. voltage. The rotor voltage is passed by slip-rings 8 to a rectifier in the exciter unit 2 having thyristors T 1, T2 controlling resistors R1, R2 for loading the rotor, the thyristors being controlled by a pulse generator 5 which determines the time periods for which the resistors Rl, R2 are connected to the output of the rectifier. Hence a variation in loading is produced on the rotor, about a mean value predetermined by the brake 3, which variation manifests itself as a torsional vibration transmitted to the part to be tested via members 1, 6. A further pulse generator (not shown) may be associated with the generator 5. Shaft part 1 may be omitted and flange 6 connected to the end 7', Fig.2 (not shown).