Non-destructive test apparatus and method for a material having a cavity therein

• US 3,960,006 A
• Filed: 12/03/1973
• Issued: 06/01/1976
• Est. Priority Date: 12/03/1973
• Status: Expired due to Term

• Current Assignee: Westinghouse Electric Corporation (Paramount Global (f/k/a ViacomCBS Inc.))
• Original Assignee: Alco Standard Corp. (Ricoh Company Limited)
• Inventors: Smith, Robert D.
• Primary Examiner(s): Myracle, Jerry W.
• Assistant Examiner(s): Kreitman, Stephen A.
• Application Number:
  US05/421,131
• Time in Patent Office: 911 Days
• Field of Search: 73/67.8 S, 73/67.8 R, 73/67.7, 73/67.9, 73/71.5 US, 73/67.5 R
• US Class Current: 73/622
• CPC Class Codes: F01D 21/003 Arrangements for testing or measuring for measuring vibrations G01H
• CPC Class Codes: G01N 2291/02854 Length, thickness
• CPC Class Codes: G01N 2291/2693 Rotor or turbine parts
• CPC Class Codes: G01N 2291/2696 Wheels, Gears, Bearings
• CPC Class Codes: G01N 29/265 by moving the sensor relative to a stationary material

Abstract

In order to detect flaws in a material having a cavity, such as a turbine rotor with a central bore, a test apparatus utilizing ultrasonic signals or waves in longitudinal, shear and surface modes, or various combinations thereof, is provided. A source of ultrasonic waves is appropriately mounted for both circumferential and axial sweeps of at least a portion of the bore. Appropriate indexing arrangements are provided to accurately determine the axial and circumferential positions of the source, and hence of any detected flaws.

Claims

1. A non-destructive test apparatus for detecting and providing three-dimensional analysis of flaws in a horizontally positioned generally cylindrical rotor having a relatively large mass of material, a central bore with a diameter small in comparison to the diameter of the rotor and providing a test cavity being located in the rotor, comprising:

signal transmitting means to be inserted into the bore of the rotor, said signal transmitting means including at least two signal sources capable of simultaneously transmitting at least two ultrasonic signals from the bore into the mass of the rotor, said ultrasonic signals being selectively chosen from among the various ultrasonic modes;

pickup means to detect said ultrasonic signals as they are reflected from discontinuities throughout the mass of the rotor material, each of said reflected ultrasonic signals being identified with the corresponding transmitted ultrasonic signal and providing information regarding the discontinuities from which they are reflected;

position determining means providing for the direct correlation of the information content of a transmitted or reflected ultrasonic signal in one mode with the information content of reflected ultrasonic signals and unreflected transmitted ultrasonic signals in another mode, the information content of said transmitted and said reflected signals relating to discontinuity characteristics throughout the mass of the rotor material, by precisely locating in a three-dimensional matrix the path through the rotor mass of each transmitted ultrasonic signal and the position of discontinuities in the rotor material evidenced by each reflected ultrasonic signal; and

recording means for preserving the information content of said transmitted and said reflected ultrasonic signals in a fashion that permits combining the individual information content of each of said transmitted and said reflected ultrasonic signals in the different modes to derive an accurate indication of the existence, position, nature size and shape of flaws in the rotor material.

2. A non-destructive test apparatus as claimed in claim 1 wherein said signal sources simultaneously transmit ultrasonic signals in different modes.

3. A non-destructive test apparatus for detecting and providing three-dimensional analysis of flaws in a horizontally positioned generally cylindrical rotor having a relatively large mass of material, a central bore with a diameter small in comparison to the diameter of the rotor and providing a test cavity being located in the rotor, comprising:

a movable carriage to be inserted into the bore of the rotor;

drive means to longitudinally advance and to rotate said movable carriage, said longitudinal advancement and said rotation being performed independently and sequentially to insure easy and accurate knowledge of the position of said movable carriage in both the longitudinal and rotational directions at all times;

a first source of ultrasonic signals to be utilized in a first mode to transmit ultrasonic signals from the bore into the mass of the rotor;

a second source of ultrasonic signals to be utilized in a second mode to transmit ultrasonic signals from the bore into the mass of the rotor simultaneously with the ultrasonic signals from said first source;

source conveying means located on said movable carriage and having said sources mounted therein, said source conveying means providing a transmitting path for ultrasonic signals from said sources;

bias means to maintain said source conveying means in engagement with the walls of the cavity;

pickup means located on said source conveying means to detect ultrasonic signals reflected from discontinuities throughout the mass of the rotor material, such reflected signals conveying information regarding the existence and nature of flaws in the rotor material;

couplant introducing means to maintain liquid couplant between said source conveying means and the walls of the cavity in the material being tested;

indexing means providing for the direct correlation of the information content of a transmitted or reflected ultrasonic signal in one mode with the information content of reflected ultrasonic signals and unreflected transmitted ultrasonic signals in another mode, the information content of said transmitted and said reflected signals relating to discontinuity characteristics throughout the mass of the rotor material, by accurately determining and indicating the axial and rotational position of said first and second sources and thus, from a knowledge of the source geometry and the characteristics of said source conveying means and the rotor material, precisely locating in a three-dimensional matrix the path through the rotor mass of each transmitted ultrasonic signal and the position of discontinuities in the rotor material evidenced by each reflected ultrasonic signal; and

recording means for preserving the information content of said transmitted and said reflected ultrasonic signals in a fashion that permits combining the individual information content of each of said transmitted and said reflected ultrasonic signals in the different modes to derive an accurate indication of the existence, position, nature, size and shape of flaws in the rotor material.

4. A non-destructive test apparatus for detecting and providing three-dimensional analysis of flaws in a horizontally positioned generally cylindrical rotor having a relatively large mass of material, a central bore with a diameter small in comparison to the diameter of the rotor and providing a test cavity being located in the rotor, comprising:

a test unit to be inserted into the bore of the rotor;

adjustable support means to fixedly mount said test unit at a predetermined location in the bore of the rotor;

a movable carriage mounted for reciprocal movement along said test unit;

first drive means mounted on said test unit to drive said movable carriage along said test unit;

first indexing means to accurately determine and indicate the position of said movable carriage along said test unit;

a first source of ultrasonic signals to transmit ultrasonic signals from the bore into the mass of the rotor;

a second source of ultrasonic signals to transmit ultrasonic signals from the bore into the mass of the rotor simultaneously with the ultrasonic signals from said first source, the ultrasonic signals of said sources being selectively chosen from the various modes;

source conveying means located on said movable carriage and having said sources mounted therein, said source conveying means providing an ultrasonic signal transmitting path to the wall of the bore;

pickup means on said source conveying means to detect ultrasonic signals reflected from discontinuities throughout the mass of the rotor material, said reflected signals conveying information regarding the existence and nature of the discontinuities in the rotor material;

bias means to urge said source conveying means toward the walls of the bore in the rotor being tested;

couplant introducing means to maintain liquid couplant between said source conveying means and the walls of the bore in the rotor being tested;

second drive means outside of the bore to rotate said test unit as a unitary structure;

second indexing means to accurately determine and indicate the position of said test unit in the circumferential direction, said first and second indexing means providing for the direct correlation of the information content of a transmitted or reflected ultrasonic signal in one mode with the information content of reflected ultrasonic signals and unreflected transmitted ultrasonic signals in another mode, the information content of said transmitted and said reflected signals relating to discontinuity characteristics throughout the mass of the rotor material, by accurately determining and indicating the axial and rotational position of said first and second sources and thus, from a knowledge of the source geometry and the characteristics of said source conveying means and the rotor material, precisely locating in a three-dimensional matrix the path through the rotor mass of each transmitted ultrasonic signal and the position of discontinuities in the rotor material evidenced by each reflected ultrasonic signal; and

recording means for preserving the information content of said transmitted and said reflected ultrasonic signals in a fashion that permits combining the individual information content of each of said transmitted and said reflected ultrasonic signals in the different modes to derive an accurate indication of the existence, position, nature, size and shape of flaws in the rotor material.

5. A non-destructive apparatus as claimed in claim 4 wherein:

said adjustable support means comprises first and second spiders each having first, second and third legs, said first and second legs being fixedly adjustable and said third leg being pneumatically adjustable;

said test unit further comprises guides extending between said adjustable support means to mount said movable carriage for movement therealong, and a threaded shaft to engage threads on said movable carriage and actuated by said first drive means, rotation of said shaft by said first drive means producing movement of said movable carriage along said guides; and

said bias means comprises a pneumatic pressure to cause said source conveying means to engage the walls of the bore with a constant pressure.

6. A non-destructive test apparatus for detecting and providing three-dimensional analysis of flaws in a horizontally positioned generally cylindrical rotor having a relatively large mass of material, a central bore with a diameter small in comparison to the diameter of the rotor and providing a test cavity being located in the rotor, comprising:

a test unit to be inserted into the bore a precisely determined distance;

a support structure at each end of said test unit to mount said test unit, each of said support structures being adjustable to snugly fit various size bores and remain stationary except when being moved along the bore;

a pair of guide rails extending between said support structures;

a movable carriage mounted on said guide rails for axial advancement along said test unit, said movable carriage having a threaded opening therein;

a threaded rod extending through said threaded opening, the threads on said threaded rod engaging the threads of said threaded opening;

a first drive motor mounted on said test unit and rotationally driving said threaded rod, rotation of said threaded rod producing axial movement of said movable carriage along said guide rails;

first indexing means to accurately determine and indicate the position of said movable carriage along said test unit;

a solid ultrasonic transmitting shoe mounted on said movable carriage;

a first source of ultrasonic signals to produce ultrasonic signals to be utilized in a first mode for scanning the surface of the bore, said first source being mounted in said shoe;

a second source of ultrasonic signals to produce ultrasonic signals to be utilized in a second mode for scanning the surface of the bore, said second source being mounted in said shoe;

bias means to urge said shoe against the surface of the bore with a constant force;

couplant introducing means to maintain a liquid couplant between said shoe and the surface of the bore;

a second drive motor positioned outside of the bore to rotate the test unit;

pickup means on said shoe to detect ultrasonic signals from said first and second sources that are reflected from discontinuities throughout the mass of the materials of the rotor, such reflected signals conveying information regarding the existence and nature of flaws in the rotor;

second indexing means to accurately determine and indicate the position of said test unit in the circumferential direction, said first and second indexing means providing for the direct correlation of the information content of a transmitted or reflected ultrasonic signal in one mode with the information content of reflected ultrasonic signals and unreflected transmitted ultrasonic signals in other modes, the information content of said transmitted and said reflected signals relating to discontinuity characteristics throughout the mass of the rotor material, by accurately determining and indicating the axial and rotational position of said first and second sources and thus, from a knowledge of the source geometry and the characteristics of said source conveying means and the rotor material, precisely locating in a three-dimensional matrix the path through the rotor mass of each transmitted ultrasonic signal and the position of discontinuities in the rotor material evidenced by each reflected ultrasonic signal; and

recording means for preserving the information content of said transmitted and said reflected ultrasonic signals in a fashion that permits combining the individual information content of each of said transmitted and said reflected ultrasonic signals in the different modes to derive an accurate indication of the existence, position, nature, size and shape of flaws in the rotor material.

7. A method for detecting and providing three-dimensional analysis of flaws in a horizontally positioned generally cylindrical rotor having a relatively large mass of material, a central bore having a diameter small in comparison to the diameter of the rotor and providing a test cavity being located in th rotor, comprising the steps:

transmitting more than one mode of ultrasonic signals from the bore into the mass of the rotor;

detecting signals reflected from discontinuities in the rotor material for each mode of ultrasonic signals utilized, said reflected signals conveying information regarding the existence and nature of discontinuities throughout the mass of the rotor material;

identifying each of said reflected ultrasonic signals with the corresponding transmitted ultrasonic signal;

correlating the information content of a transmitted or reflected ultrasonic signal in one mode with the information content of reflected ultrasonic signals and unreflected transmitted ultrasonic signals in another mode, the information content of said transmitted and said reflected signals relating to discontinuity characteristics throughout the mass of the rotor material, by accurately determining in a three-dimensional matrix the path through the rotor mass of each transmitted ultrasonic signal and the location of discontinuities in the rotor material evidenced by each reflected ultrasonic signal; and

combining the information content of said transmitted and said reflected ultrasonic signals in the different modes to derive an accurate indication of the position, nature, size and shape of flaws in the rotor material.

8. A method for detecting and providing three-dimensional analysis of flaws in a horizontally positioned generally cylindrical rotor having a relatively large mass of material, a central bore having a diameter small in comparison to the diameter of the rotor and providing a test cavity being located in the rotor, comprising the steps:

transmitting a first mode of ultrasonic signals produced by a first source of ultrasonic signals from the bore into the mass of the rotor;

accurately determining the position of said first source at all times during the transmission of ultrasonic signals therefrom into the mass of the rotor;

detecting ultrasonic signals from said first source that are reflected from discontinuities in the rotor material, said reflected signals conveying information regarding the existence and nature of flaws in the rotor material;

recording the information conveyed by reflected ultrasonic signals originally transmitted from said first source as a function of the position of said first source;

transmitting a second mode of ultrasonic signals produced by a second source of ultrasonic signals from the bore into the mass of the rotor;

accurately determining the position of said second source at all times during the transmission of ultrasonic signals therefrom into the mass of the rotor;

detecting ultrasonic signals from second source that are reflected from discontinuities in the rotor material, said reflected signals conveying information regarding the existence and nature of flaws in the rotor material, the discontinuities from which the ultrasonic signals of said first and second sources are reflected being located throughout the mass of the rotor material;

recording the information conveyed by reflected ultrasonic signals originally transmitted from said second source as a function of the position of said second source;

correlating the information content of a transmitted or reflected ultrasonic signal in one mode with the information content of reflected ultrasonic signals and unreflected transmitted ultrasonic signals in another mode, the information content of said transmitted and said reflected signals relating to discontinuity characteristics throughout the mass of the rotor material, by accurately determining in a three-dimensional matrix the path through the rotor mass of each transmitted ultrasonic signal and the location of discontinuities in the rotor material evidenced by each reflected ultrasonic signal; and

combining the information content of said transmitted and said reflected ultrasonic signals in the different modes to derive an accurate indication of the position, nature, size and shape of flaws in the rotor material.

9. A method as claimed in claim 8 and further comprising the steps:

transmitting a third mode of ultrasonic signals produced by a third source of ultrasonic signals from the bore into the mass of the rotor;

accurately determining the position of said third source at all times during the transmission of ultrasonic signals therefrom into the mass of the rotor;

detecting ultrasonic signals from said third source that are reflected from discontinuities in the rotor material, said reflected signals conveying information regarding the existence and nature of flaws in the rotor material; and

recording the information conveyed by reflected ultrasonic signals originally transmitted from said third source as a function of the position of said third source.

10. A method as claimed in claim 8 and further comprising the step of repeating the steps of claim 8 at a subsequent time to determine if flaw removal has been successful or if flaw characteristics have changed with the passage of time.

11. A method for detecting and providing three-dimensional analysis of flaws in a horizontally positioned generally cylindrical rotor having a relatively large mass of material, a central bore having a diameter small in comparison to the diameter of the rotor and providing aa test cavity being located in the rotor, comprising the steps:

repetitively indexing a first source of ultrasonic signals, said first source being adapted for motion in both the axial and circumferential directions, to move in incremental steps in one of said directions, said first source producing ultrasonic signals to be utilized in a first mode;

acuating said first source to have said first mode ultrasonic signals scan the bore in the other of said directions of motion after each of said incremental steps;

accurately determining the position of said first source in both the axial and circumferential directions at all times;

detecting by pulse-echo techniques ultrasonic signals from said first source that are reflected from discontinuities in material of the rotor, such reflected signals conveying information regarding the existence and nature of flaws in the rotor;

recording the information conveyed by the reflected ultrasonic signals from said first source as a function of the axial and circumferential position of said first source.

repetitively indexing a second source of ultrasonic signals, said second source being adapted for motion in both the axial and circumferential directions, to move in incremental steps in one of said directions, said second source producing ultrasonic signals to be utilized in a second mode;

actuating said second source to have said second mode ultrasonic signals scan the bore in the other of said directions of motion after each of said incremental steps;

accurately determining the position of said second source in both the axial and circumferential directions at all times;

detecting by pulse-echo techniques ultrasonic signals from said second source that are reflected from discontinuities in the material of the rotor, such reflected signals conveying information regarding the existence and nature of flaws in the rotor;

recording the information conveyed by the reflected ultrasonic signals from said second source as a function of the axial and circumferential position of said second source;

repetitively indexing third source of ultrasonic signals, said third source being adapted for motion in both the axial and circumferential directions, to move in incremental steps in one of said directions, said third source producing ultrasonic signals to be utilized in a third mode;

actuating said third source to have said third mode ultrasonic signals scan the bore in the other of said directions of motion after each of said incremental steps;

detecting by pulse-echo techniques ultrasonic signals from said third source that are reflected from discontinuities in the material of the rotor, such reflected signals conveying inormation regarding the existence and nature of flaws in the rotor, the discontinuities from which the ultrasonic signals of said first, second and third sources are reflected being located throughout the mass of the rotor material;

recording the information conveyed by the reflected ultrasonic signals from said third source as a function of the axial and circumferential position of said third source;

correlating the information content of a transmitted or reflected ultrasonic signal in one mode with the information content of reflected ultrasonic signals and unreflected transmitted ultrasonic signals in other modes by accurately determining in a three-dimensional matrix the path through the rotor mass of each transmitted ultrasonic signal and the location of discontinuities in the rotor material evidenced by each reflected ultrasonic signal; and

combining the information content of said transmitted and said reflected ultrasonic signals in the different modes to derive an accurate indication of the position, nature, size and shape of flaws in the rotor material.

12. A method as claimed in claim 11 wherein said sources are indexed in the axial direction and scanned in the circumferential direction.

13. A method as claimed in claim 11 wherein said sources re indexed in the circumferential direction and scanned in the axial direction.