FOREIGN MATTER INSPECTION METHOD FOR METAL GRAIN

PURPOSE:To automate the foreign matter inspection of metal grains by projecting light on a body to be inspected which is conveyed in plural directions, extracting light components with wavelengths of red, green, and blue from reflected light from the body to be inspected and converting them into an electric signal, and comparing them with a reference value. CONSTITUTION:A belt conveyor 1 with an electromagnetic feeder 1a conveys the body A to be inspected which consists principally of sponge titanium grains of desired side (normally 1-10mm). A straightening plate 2 which narrows down the flow width of the body A to be inspected is arranged on one side of the intermediate part of this conveyor 1 and a halogen lamp 4 for plural-beam projection 3 and a sensor probe 6 which receives the reflected light from the body A to be inspected are arranged on the downstream side of the straightening plate 2. Then the conveyor 1 and feeder 1a are driven to supply the body A to be inspected, and the lamp 4 is turned on. Then the reflected light 5 from the body A to be inspected is guided to a color measuring instrument 8 through the probe 6 to extract the light beams with the wavelengths of red, green, and blue, which are converted into electric signals and outputted. An arithmetic unit 9 performs arithmetic operation based upon a specific expression by using the data from the unit 8 and the result of the foreign matter inspection is displayed on a display device 10.