ULTRASONIC INSPECTION METHOD AND APPARATUS

• US 3,791,199 A
• Filed: 08/01/1969
• Issued: 02/12/1974
• Est. Priority Date: 08/01/1969
• Status: Expired due to Term

• Current Assignee: LTV Steel Company, Inc. (LTV Corp.)
• Original Assignee: James M. Toth, Tyler W. Judd
• Inventors: Toth, James M., Judd, Tyler W.
• Primary Examiner(s): Queisser, Richard C.
• Assistant Examiner(s): Beauchamp, John P.
• Application Number:
  US04/846,819
• Time in Patent Office: 1,656 Days
• Field of Search: 73/67.5-67.9
• US Class Current: 73/609
• CPC Class Codes: G01N 29/38 by time filtering, e.g. using time gates

Abstract

Testing method and apparatus, incorporating a pair of transducers positioned on opposite sides of a weld seam. The transducers are alternately energized, and signals from the transducers are gated to develop signals representative of defects in various regions of the workpiece under test. Individual references are established for the different regions, and the signals are compared with the associated references. Output signals representing major defects are generated in accordance with various relationships of signals from the different regions of the workpiece.

Claims

1. A method of testing a metallic article that includes a weld seam therein for flaws, comprising:

a. introducing signals into the article;

b. detecting signals from the article and characterizing them as from a first region that includes a portion of the weld seam and a second region of the article adjacent to the weld seam;

c. establishing individual thresholds for the first and second regions;

d. comparing the detected signals from the different regions with the associated established thresholds and e. generating an output flaw signal for the first region when the first region detected signal exceeds its threshold indicating an anomaly in the article and the second region detected signal is less than its threshold indicating the absence of a lamination in the second region.

2. A method according to claim 1, in which the established thresholds for said two regions are different.

3. A method according to claim 1, including generating said output flaw signal when the detected signal from the first region exceeds a threshold R for at least a time T, and the detected signal from the second region is less than the threshold R.

4. A method according to claim 1, including characterizing signals also as from a third region of the article that includes another portion of the weld seam and a fourth region of the article adjacent to the weld seam on the side opposite from the second region, and generating an output flaw signal when the detected signals from the first and third regions are each greater than a threshold R and the detected signals from the second and fourth regions are each less than the threshold R.

5. Apparatus for testing a metallic article that includes a weld seam therein for flaws, comprising:

a. means for introducing signals into the article;

b. means for detecting signals from the article and characterizing them as from a first region that includes a portion of the weld seam and a second region of the article adjacent to the weld seam;

c. means for establishing individual thresholds for the first and second regions;

d. means for comparing the detected signals from the two regions with the associated established thresholds and e. means responsive to the means (d) for generating an output flaw signal for the first region when the first region detected signal exceeds its threshold indicating an anomaly in the article and the second region detected signal is less than its threshold indicating the absence of a lamination in the second region.

6. Apparatus according to claim 5, in which the means (c) includes means for establishing different thresholds for the two article regions.

7. Apparatus according to claim 5, in which the means (e) includes means for generating said output flaw signal when the detected signal from the first region exceeds a threshold R for at least a time T, and the detected signal from the second region is less than the threshold R.

8. Apparatus according to claim 5, in which the means (b) includes means for characterizing the detected signals from the article as from a third region that includes another portion of the weld seam and a fourth region of the article adjacent to the weld seam on the side opposite from the second region, and the means (e) includes means for generating an output flaw signal when the detected signals from the first and third regions are each greater than a threshold R and the detected signals from the second and fourth regions are each less thAn the threshold R.

9. A method according to claim 1, in which the signals that are introduced into the article are ultrasonic.

10. Apparatus according to claim 5, in which the means (a) comprises means for introducing ultrasonic signals into the article.