DETECTING DEVICE FOR WELDING GROOVE CENTER POSITION

PURPOSE:To exactly detect a groove center position even if a groove shoulder part is indistinct by bringing a light cutting position signal of a welding groove part to differential operation and detecting rough and detailed shapes of the groove shoulder part, and detecting a center position of a groove part, based on a result of its detection. CONSTITUTION:A welding groove part is irradiated by a linear light beam, and an optical cut image obtained thereby is brought to image pickup and inputted as a video signal to a signal processing circuit 11. A light cutting position detecting circuit 111 detects a light cutting position signal by the video signal. A groove shoulder part rough shape detecting means 117 and a groove shoulder part detailed shape detecting means 118 detect a rough shape and its position, and a detailed shape and its position of a groove part from a result of operation of a macro two-story difference and a micro two-story difference of the light cutting position detecting signal. A groove shoulder part cross section shape detecting circuit 119 decides a shape of the right and the left groove shoulder parts, based on a result of said detection, and selects one of said rough position and detailed position, based on a result of its decision. A groove center position detecting means 120 calculates a groove center position, based on an output of the detecting circuit 119.