Method and apparatus for monitoring cracks of a rotatable body
First Claim
1. A method for monitoring cracks of a rotatable body, the method comprising the steps of detecting cracks by measuring acoustic emission signals, measuring vibrations of the rotatable body, calculating the position of the cracks on a basis of the measured acoustic emission signal, comparing assumed variations with the measured vibrations and evaluating the depth of cracks from the result of this comparison, and wherein the step of detecting of cracks by measuring acoustic emission signals is performed by detecting first acoustic emission signals from two first acoustic emission detectors attached to the rotatable body, detecting second acoustic emission signals from two second acoustic emission detectors attached to bearings of the rotatably body and by eliminating acoustic emission signal portions caused by reasons other than cracking from those acoustic emission signals.
1 Assignment
0 Petitions
Accused Products
Abstract
A method and apparatus for monitoring cracks of a rotatable body by detecting cracks by measuring accoustic emission signals and evaluating the depth of cracks from the result of the comparison of assumed vibrations of the rotatable body and its measured vibrations. By this method and apparatus not only the beginning of cracking of the rotatable body, but also the progress of cracking on an online basis can be detected and monitored.
-
Citations
18 Claims
- 1. A method for monitoring cracks of a rotatable body, the method comprising the steps of detecting cracks by measuring acoustic emission signals, measuring vibrations of the rotatable body, calculating the position of the cracks on a basis of the measured acoustic emission signal, comparing assumed variations with the measured vibrations and evaluating the depth of cracks from the result of this comparison, and wherein the step of detecting of cracks by measuring acoustic emission signals is performed by detecting first acoustic emission signals from two first acoustic emission detectors attached to the rotatable body, detecting second acoustic emission signals from two second acoustic emission detectors attached to bearings of the rotatably body and by eliminating acoustic emission signal portions caused by reasons other than cracking from those acoustic emission signals.
- 5. An apparatus for monitoring cracks of a rotatable body comprising a first pair of accoustic emission detectors attached to the rotatable body, a second pair of accoustic emission detectors attached to the bearings of the rotatable body, means for detecting cracks by extracting accoustic emission signals caused by cracks, means for calculating the position of cracks based on the time difference between the accoustic emission signals from the detectors of the first pair, means for comparing assumed vibrations with measured vibrations, means for evaluating the depth of cracks from the result of this comparison and means for displaying the cracks.
- 8. A method, for monitoring cracks of a rotatable body, the method comprising the steps of detecting cracks by measuring acoustic emission signals, measuring vibrations of the rotatably body, calculating the position of cracks on the basis of the measured acoustic emission signals, comparing assumed vibrations with the measured vibrations and evaluating the depth of cracks from a result of this comparison, when the measured acoustic emission signals include two signals detected at two axially spaced positions of the rotatable body, the position of the cracks is calculated on the basis of the time difference between the two signals, the assumed vibrations of the rotatable body are calculated on the basis of the calculated position of the cracks and of the assumed depths of the cracks, and wherein the detecting of cracks by measuring acoustic emission signals is performed by detecting first acoustic emission signals from two first acoustic emission detectors attached to the rotatable body, detecting second acoustic emission signals from two second acoustic emission detectors attached to the bearings of the rotatable body and by eliminating acoustic emission signal portions caused by other reasons than cracking from those acoustic emission signals.
-
10. A method for monitoring cracks of a rotatable body, the method comprising the steps of:
-
measuring two acoustic emission signals at two axially spaced positions of the rotatable body; determining a position of cracks of said rotatable body as a function of a time difference between receipt of said two acoustic emission signals; measuring vibrations of the rotatable body; comparing the measured vibrations with predetermined vibrations for cracks of a known depth at the determined position of the cracks; and repeating the comparison by changing the predetermined vibration of cracks of known depth until the difference between the measured vibrations and the predetermined vibrations of cracks of a known depth fall within an acceptable value to thereby determine the actual depth of said cracks. - View Dependent Claims (11, 12, 13, 14)
-
-
15. An apparatus for determining a positioning and depth of cracks in a rotating body, the apparatus comprising detector means including two detectors axially spaced along said rotating body for producing two acoustic emission signals, first means for determining a location of cracks in said rotating body by comparing a time difference between receipt of the two acoustic emission signals to each of said two spaced apart detectors;
- vibration detecting means for producing vibration signals caused by cracks in said rotating body;
second means for comparing predetermined vibration signals representing cracks of a known depth with said vibration signals, said second means repeatedly selecting different predetermined vibration signals with said vibration signals until a difference therebetween is within a predetermined value to thereby determine the actual depth of said cracks in said rotating body. - View Dependent Claims (16, 17, 18)
- vibration detecting means for producing vibration signals caused by cracks in said rotating body;
Specification