Weld-position detector provided with an optical axis adjustment means and used with a robot welding machine

A weld-position detector, for detecting weld portions of a workpiece to be welded by an automatic welding machine, comprising:

• a laser-beam projecting means including a laser source and a projecting lens, said projecting lens projecting a detection laser-beam from said laser source in a fixed direction;
• a scanning means including a movable reflecting mirror and a galvanometer, said galvanometer moving said reflecting mirror so as to direct the detection laser-beam coming from said laser-beam projecting means along said fixed direction toward the weld portions of the workpiece and to scan the detection laser-beam across the weld portions of the workpiece upon being projected by the laser-beam projecting means;
• and
• a light-receiving means including a light-receiving lens and a light sensor, said light-receiving means receiving the detection laser-beam reflected from the weld portions of the workpiece to therein permit the light sensor to detect the detection laser-beam,
• wherein said laser-beam projecting means, scanning means, and light-receiving means are beforehand produced as single independent units;
• and
• a fixture for accurately mounting, at predetermined positions thereof, said respective three independent units, said fixture having a first reference face to which said laser-beam projecting means and said light-receiving means are commonly and fixedly attached, and a second reference face thereof to which said scanning means provided with an optical axis adjusting means is adjustably attached, said first and second reference faces of said fixture being opposite faces formed in a plate member,
• wherein said optical axis adjusting means adjusts position and posture of said scanning means with respect to the predetermined position thereof to therein allow alignment of the optical axis of the detection laser-beam projected by said laser-beam projecting means with a predetermined axis lying in a predetermined plane of said light-receiving means.