Method for the automatic inspection of a welding seam by means of heat flow thermography

A method for the automatic inspection of a welding seam using heat flow thermography,

• a. in which an object (1), which is to be examined, with a welding seam (4) is provided,
• b. wherein the object (1) is excited by means of at least one excitation source (9), and
• c. the heat flow (11) produced by the excitation is detected in a series of thermal images using at least one infrared sensor (10),
• wherein
• d. a feature vector (W(N)) is produced, which is a time course of the detected heat flow (11),
• e. wherein a first characteristic thermal image (T1) is dynamically determined from the series of thermal images using the feature vector (W(N)), and the first characteristic thermal image (T1) has a minimum heat flow (Wmin) through the object (1), and
• f. a second characteristic thermal image (T2) is dynamically determined from the series of thermal images using the feature vector (W(N)), and the second characteristic thermal image (T2) has a maximum heat flow (Wmax) through the object (1), and
• g. wherein a heat flow (13) directly from the excitation source (9) to the characteristic thermal images (T1, T2) has already dissipated, if it is apparent from the series of thermal images, and
• h. a suitable thermal image (TF1, TF2, TF3, TF4) from the series of thermal images is used to detect and evaluate the welding seam (4) with respect to defects (5, 6, 7, 8) of various defect types, for each defect type, the characteristic thermal images (T1, T2) being used as references to determine the respective suitable thermal image (TF1, TF2, TF3, TF4).