Automated radiographic inspection system

Abstract

In an automated real-time radiographic inspection system for detecting flaws, defects or inhomogeneities in manufactured objects, the objects (10, 11, 12, . . . ) to be tested are moved on a conveyor (20) in succession past an X-ray source (30). Penetrating X-ray radiation is transmitted through the objects (10, 11, 12, . . . ) to cause an image to be formed for each object in succession by an electronic imaging system (40). The imaging system (40) generates digital signals representative of the image for each object, and transmits the digital signals to a data processor/comparator (50). One of the objects (10, 11, 12, . . . ) may be considered as a reference object against which the other objects are compared for structural homogeneity. Thus, the electronic images of the objects (11, 12, . . . ) could be compared with the electronic image of, for example, the object (10). Alternatively, the electronic images of the test objects could be compared with an electronic reference image programmed into the data processor/comparator (50), the programmed reference image. The comparison performed by the data processor/comparator (50) is a subtraction process, which eliminates background features common to test and reference images. Thus, any flaw appearing in a test image, but not present in the reference image, stands out in sharp detail. When a flaw occurs in a test image, the subtractive process results in a non-null signal, which activates a conveyor control mechanism (70) for stopping the conveyor (20) so as to enable rejection of the flawed test object.