Method and device for detecting defects within a test object

Patent metadata

Field	Value
Publication number	US-9829468-B2
Application number	US-201214370651-A
Country	US
Kind code	B2
Filing date	Dec 28, 2012
Priority date	Jan 12, 2012
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

A device and a method for detecting at least one defect in a test object ( 2 ). At least one test head ( 1 ) radiates an ultrasonic signal at different measuring points (MP) into the test object ( 2 ) with each point at an insonation or radiation angle (α) in order to ascertain multiple measurement data sets (MDS). The angle is constant for each data set (MDS). An analyzing unit ( 4 ) carries out an SAFT (Synthetic Aperture Focusing Technique) analysis for each ascertained measurement data set (MDS) using a common reconstruction grid (RG) inside the test object ( 2 ) in order to calculate an SAFT analysis result for each measurement data set (MDS). The analyzing unit ( 4 ) superimposes the calculated SAFT analysis results in order to calculate an orientation-independent defect display value (S RP ) for each reconstruction point (RP) of the common reconstruction grid (RG).

First claim

The invention claimed is:

1. A method for detecting at least one defect within a test object, the method comprising the steps:
(a) determining a plurality of measurement data sets by insonating an ultrasound signal into the test object respectively at various measurement points such that at a first measurement point of the various measurement points a first insonation angle for a first measurement data set of the plurality of measurement data sets is different from a second insonation angle at the first measurement point for a second measurement data set of the measurement data sets,
(b) carrying out a Synthetic Aperture Focusing Technique (SAFT) evaluation for each measurement data set,
wherein the evaluation is determined by using a common reconstruction grid within the test object for calculating the SAFT evaluation result for each measurement data set;
(c) superposing the calculated SAFT evaluation results, in order to calculate an orientation-independent defect display value for each reconstruction point of the reconstruction grid; and
(d) detecting the at least one defect within the test object based on the calculated orientation-independent defect display value.

2. The method as claimed in claim 1 , further comprising weighting the calculated SAFT evaluation results of the measurement data sets evaluated and determined in order to level the amplitude level before the superposition of the SAFT evaluation results.

3. The method as claimed in claim 2 , further comprising separately storing the SAFT evaluation results, calculated for the various insonation angles of the various measurement data sets, and selecting the SAFT evaluation results for the superposition with the aid of the insonation angle.

4. The method as claimed in claim 1 , further comprising rectifying and smoothing the superposed SAFT evaluation results by lowpass filtering.

5. The method as claimed in claim 1 , wherein the measurement positions lie in a measurement network on the surface of the test object.

6. The method as claimed in claim 1 , further comprising, before the determination of the measurement data sets, adjusting the measurement positions by aid of a reflected echo signal of an adjustment reflector.

7. The method as claimed in claim 1 , wherein the insonating of the ultrasound signal is performed by a single-oscillator test head or by a group radiator test head,
wherein the isonating is performed at the various measurement points into the test object and the respective insonation angle is set for the determination of the measurement data set; and the method further comprises:
amplifying and subsequently digitizing analog echo ultrasound signals reflected by the test object for the various measurement points for digitizing the signals to form measurement point echo data, which form the measurement data set of the test object.

8. The method as claimed in claim 7 , further comprising moving the single-oscillator test head or the group radiator test head for insonating the ultrasound signals and for recording the echo ultrasound signals continuously relative to the surface of the test object.

9. The method as claimed in claim 1 , further comprising:
insonating the ultrasound signal into the test object as a longitudinal wave and/or a transverse wave.

10. The method as claimed in claim 1 , further comprising displaying the calculated defect display values of the reconstruction grid to a tester two-dimensionally in sectional views or three-dimensionally on a display.

11. The method as claimed in claim 1 , further comprising comparing the calculated defect display values of the examined test object respectively with setpoint values of a stored model of the test object to be examined, for calculating difference values which indicate a defect of the test object when predetermined tolerance threshold values are exceeded.

12. The method as claimed in claim 11 , further comprising automatically rejecting a test object identified as defective.

13. A method according to claim 1 , wherein the insonating angle for all measurement points in a measurement data set is constant.

14. A device for detecting at least one defect within a test object, the device comprising:
at least one test head configured for insonating into the test object an ultrasound signal at various measurement points,
wherein in order to determine the measurement data sets, the device is configured such that at a first measurement point of the various measurement points the ultrasound signal is respectively insonated at a first insonation angle into the test object for generating a first measurement data set of a plurality of measurement data sets, and for a second measurement data set of the plurality of measurement data sets the ultrasound is insonated at the first measurement point at a second insonation angle different from the first insonation angle; and
an evaluation unit configured to carry out an Synthetic Aperture Focusing Technique (SAFT) evaluation for each measurement data set determined, the evaluation unit is configured to use a common reconstruction grid within the test object for calculating an SAFT evaluation result for each measurement data set, the evaluation unit is configured to superpose the calculated SAFT evaluation results for calculating an orientation-independent defect display value for each reconstruction point of the common reconstruction grid,
wherein the device is configured to detect the at least one defect within the test object based on the calculated orientation-independent defect display value.

15. The device as claimed in claim 14 , wherein the evaluation unit is configured to weight the calculated SAFT evaluation results of the measurement data sets determined, in order to level the amplitude level before the superposition of the SAFT evaluation results.

16. The device as claimed in claim 14 , wherein the test head is configured to move continuously relative to a surface of the test object in order to determine the measurement data sets.

Assignees

• Siemens Ag

Inventors

• Heinrich Werner
• Mooshofer Hubert

Classifications

• G01N29/221 Primary

  Arrangements for directing or focusing the acoustical waves (electronic orientation or focusing G01N29/262; sound directing or focusing G10K11/26; mechanical steering of sound transducers or their beams G10K11/35) · CPC title

• G01N2291/044

  Internal reflections (echoes), e.g. on walls or defects · CPC title

• G01N29/043

  in the interior, e.g. by shear waves · CPC title

• G01N29/4418

  with a model, e.g. best-fit, regression analysis · CPC title

• G01N29/041

  on the surface of the material, e.g. using Lamb, Rayleigh or shear waves · CPC title