United States Patent m
Yaroshuk et al.
4,253,768  Mar. 3, 1981
 PROCESSING SYSTEM FOR DETECTION AND THE CLASSIFICATION OF FLAWS ON METALLIC SURFACES
 Inventors: Nicholas Yaroshuk, White Oak;
Miklos Sarkozi, Murrysville; Robert
C. Miller, Penn Hills; Paul G.
Kennedy, Monroeville, all of Pa.
 Assignee: Westinghouse Electric Corp.,
 Appl. No.: 932,235
 Filed: Aug. 9, 1978
 Int. CI.* G01N 21/32
 U.S. CI 356/431; 250/563;
 Field of Search 356/51, 237, 430, 431,
356/445; 250/563, 572
 References Cited
U.S. PATENT DOCUMENTS
2,975,293 2/1955 Kruse, Jr. et al 250/219
3,749,496 7/1973 Heitanen et al 356/73
3,781,117 12/1973 Laycaketal 356/200
3,781,531 12/1973 Baker 235/151.3
3,804,534 4/1974 Clarke 356/237
3,812,373 5/1974 Hosoe et al 250/562
3,834,822 9/1974 Stapleton et al 356/431
3,843,890 10/1974 Anthony, Jr. et al 250/563
3,900,265 8/1975 Merlen et al 356/200
3,920,970 11/1975 Slaker 235/151.3
3,984,189 10/1976 Seki et al 356/73
Primary Examiner—John K. Corbin
Assistant Examiner—Bruce Y. Arnold
Attorney, Agent, or Firm—R. A. Stoltz
This invention is a system of automatically classifying defects both for sorting defective products (metallic surfaces, especially tube surfaces) as to the reworking operation required for correcting the defect, and for classifying the defect as to the preceding manufacturing operation which is the most probable cause of that defect and sending a signal to that operation to provide for adjustments to minimize future defects. The system uses a source of electromagnetic radiation (typically a laser beam which is scanned across the surface) and at least two sensors (adjusted such that the radiation is reflected from a defect-free surface principally received by one of the sensors but that there is a measured amount of radiation in the other sensor). An average signal of the principal sensor is developed as a function of scan position. Threshold circuitry detects when the ratio of sensor signal to average signal varies by a predetermined amount. Special circuitry is used to detect the essentially simultaneous occurrence of at least two different preselected combinations of signal variations to identify the type of defect.
10 Claims, 3 Drawing Figures