METHOD FOR RECOGNIZING POSITION OF TAPPED HOLE

摘要

PURPOSE:To provide a method for detecting position of tapped hole by which the presence of a lower hole in a thread-fastenable extent can be discriminated after detecting an upper hole by utilizing the partial circular-arcuate shape of the upper hole. CONSTITUTION:A gradation picture is scanned by using a contour scanning window A provided with a plurality of density correlating lines perpendicular to a scanning contour equal to a circular contour containing circular-arcuate pasts on the gradation picture obtained by taking the image of an object to be thread-fastened constituted of the upper hole of a thread-fastenable part containing a circular-arcuate shape with an image picking-up means. Then the position of the window A at which the number of such density correlating lines that the absolute values of the differences between the sums of measured density values of inner density correlating lines B and the sums of measured density values of outer density correlating lines C become larger than a prescribed density threshold becomes the maximum is found and whether or not the center of a lower hole exists in the thread-fastenable extent is discriminated by using the position as the reference position of the upper hole.