US4502331A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for ultrasonic inspection of turbine disc rims
Assignee: Southwest Research Institute
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Filing: 1983-09-14
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Granted: 1985-03-05
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Expires: 2003-09-14
Abstract
Abstract Low pressure turbine disc rims are inspected by a method in which an ultrasonic beam is directed into a disc rim steeple from a location on the disc rim web. Reflected waves are received and signals indicative thereof are produced for display. A predetermined time window is established on the display, based on the time-of-flight difference between the top of the steeple and the disc rim. The presence of signals within the time window on the display is determined to indicate the presence of a crack. Cracks located along the steeple serrations and oriented in a generally tangential direction to the steeple cross section are detected by producing an ultrasonic beam directed along a line normal to the bottom of a steeple. Cracks located at the bottom of a blade groove at the steeple root and oriented in a generally radially direction can be detected by producing an ultrasonic beam skewed at an acute angle relative to the line normal to the bottom of a steeple.
Inventors
- 👤 Gurvinder P. Singh
- 👤 Richard A. Cervantes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 17:59
CPC Classifications
G; G01; G01N; G01N29/00; G01N29/36; G01N29/38; G01N29/04; G01N29/07; G01N29/11; G01N2291/00; G01N2291/04; G01N2291/044; G01N2291/26; G01N2291/269; G01N2291/2693
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
106 words
A method of detecting cracks in a turbine disc rim having a web area and adjacent integral, serrated steeples with or without turbine blades mounted therein, comprising the steps of: producing an ultrasonic beam of shear waves traveling in a radial direction; directing said waves into a steeple from a location on the disc rim web area; receiving reflected waves and producing signals indicative thereof; displaying the reflected wave signals; establishing a predetermined time window on the display based on the time-of-flight difference between the top of the steeple and the disc rim; and determining the presence of signals in the display within the time window.
Claim 2
Independent Claim
106 words
A method of detecting cracks in a turbine disc rim having a web area and adjacent integral, serrated steeples with or without turbine blades mounted therein, comprising the steps of: producing an ultrasonic beam of shear waves traveling in a radial direction; directing said waves into a steeple from a location on the disc rim web area; receiving reflected waves and producing signals indicative thereof; displaying the reflected wave signals; establishing a predetermined time window on the display based on the time-of-flight difference between the top of the steeple and the disc rim; and determining the presence of signals in the display within the time window.
Claim 3
Dependent Claim
41 words
The method of claim 1 further comprising the steps of: establishing within said time window individual time windows based on the time-of-flight differences between adjacent steeple serrations; and determining the presence of signals in the display within the individual time windows.
Claim 4
Independent Claim
33 words
The method of claims 1 or 2 further comprising the step of: scanning the disc rim web area with said ultrasonic beam to direct said waves into the steeple along its entire length.
Claim 5
Independent Claim
152 words
A method of detecting cracks in a turbine disc rim having a web area and an adjacent area of integral, serrated steeples with or without turbine blades mounted therein, comprising the steps of: producing an ultrasonic beam of shear waves traveling in a radial direction; skewing the beam at an acute angle relative to a line normal to the bottom of a steeple; directing waves of the skewed ultrasonic beam into the steeple root area from a location on the disc rim web area; scanning along the disc rim web with the skewed beam; receiving reflected waves as the beam is scanned and producing signals indicative thereof; continuously recording the reflected wave signals as the disc rim is scanned to produce a record thereof; establishing predetermined time windows on the record based on the time-of-flight to a predetermined, suspected crack location; and determining the presence of recorded signals within the time windows.
Claim 6
Independent Claim
152 words
A method of detecting cracks in a turbine disc rim having a web area and an adjacent area of integral, serrated steeples with or without turbine blades mounted therein, comprising the steps of: producing an ultrasonic beam of shear waves traveling in a radial direction; skewing the beam at an acute angle relative to a line normal to the bottom of a steeple; directing waves of the skewed ultrasonic beam into the steeple root area from a location on the disc rim web area; scanning along the disc rim web with the skewed beam; receiving reflected waves as the beam is scanned and producing signals indicative thereof; continuously recording the reflected wave signals as the disc rim is scanned to produce a record thereof; establishing predetermined time windows on the record based on the time-of-flight to a predetermined, suspected crack location; and determining the presence of recorded signals within the time windows.
Claim 7
Dependent Claim
19 words
The method of claim 4 wherein the angle of beam skew is 45° in a clockwise rotation from normal.
Claim 8
Dependent Claim
20 words
The method of claim 4 wherein the angle of beam skew is 60° in a counter clockwise rotation from normal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-03-04 | 1988-09-03 | 1989-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-03-04 | 1992-09-03 | 1993-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-03-04 | 1996-09-03 | 1997-03-05 | $7700.00 | Window Closed / Lapsed |