Process for the early detection of a crack in a rotating shaft

Claim 2

A process for the early detection of a crack in a rotating shaft, in which signals representative of flexural vibrations of the shaft are picked up as a function of rotational angle by means of vibration sensors in at least two radial directions, and the signals are transmitted to a signal processor which uses the signals to ascertain the harmonic vibration components with at least a single rotational frequency and then the processor forms at least a single rotational-frequent vibration orbit by means of a vectorial combination of the vibration components, the improvement comprising in that the signal processor vectorially decomposes at least the single rotational-frequent vibration orbit formed on the basis of the harmonic vibration components into a forward whirl turning in the same rotational direction as the shaft and into a backward whirl turning in the opposite direction to the rotation of the shaft and in that the backward whirl is compared with a reference base-line ascertained in one of the new and normal states.

Claim 3

A process for the early detection of a crack in a rotating shaft, in which signals representative of flexural vibrations of the shaft are picked up as a function of rotational angle by means of vibration sensors in at least two radial directions, and the signals are transmitted to a signal processor which uses the signals to ascertain the harmonic vibration components with at least a single rotational frequency and then the processor forms at least a single rotational-frequent vibration orbit by means of a vectorial combination of the vibration components, the improvement comprising in that the signal processor vectorially decomposes at least the single rotational-frequent vibration orbit formed on the basis of the harmonic vibration components into a forward whirl turning in the same rotational direction as the shaft and into a backward whirl turning in the opposite direction to the rotation of the shaft and in that the backward whirl is compared with a reference base-line ascertained in one of the new and normal states, and wherein acceleration pick-ups are utilized as the vibration sensors positioned in one rotational plane and spaced apart by 90° with respect to each other along the circumference of the shaft, and the signals of the acceleration pick-ups are transmitted to the signal processor via a telemetric device.

Claim 4

A process for the early detection of a crack in a rotating shaft, in which signals representative of flexural vibrations of the shaft are picked up as a function of rotational angle by means of vibration sensors in at least two radial directions, and the signals are transmitted to a signal processor which uses the signals to ascertain the harmonic vibration components with at least a single rotational frequency and then the processor forms at least a single rotational-frequent vibration orbit by means of a vectorial combination of the vibration components, the improvement comprising in that the signal processor vectorially decomposes at least the single rotational-frequent vibration orbit formed on the basis of the harmonic vibration components into a forward whirl turning in the same rotational direction as the shaft and into a backward whirl turning in the opposite direction to the rotation of the shaft and in that the backward whirl is compared with a reference base-line ascertained in one of the new and normal states, and wherein acceleration pick-ups are utilized as the vibration sensors positioned in one rotational plane and spaced apart by 90° with respect to each other along the circumference of the shaft, and the signals of the acceleration pick-ups are transmitted to the signal processor via a telemetric device.