Apparatus for automatically guiding a welding gun along a programmed welding seam

A welding robot, comprising:

• a base;
• an arm mounted on said base for pivotal movement about mutually perpendicular axes;
• adjustment means for effecting a variance of the length of said arm at one end thereof;
• a first decoder means for measuring the angle of traverse of said arm about one of said mutually perpendicular axes;
• mounting means on said one end of said arm;
• commuter means mounted on said mounting means, said commuter means including welding gun means and support means supporting said welding gun means for movement in two mutually perpendicular planes separate from planes defined by the movement of said arm about said mutually perpendicular axes, said commuter means including a housing, a drive motor mounted on said housing, a first axle rotatably supported on said housing and driven by said drive motor, a guide bar secured to said first axle for movement therewith, a slide block slidably secured to said guide bar and having means thereon defining a second block axle extending parallel to said first axle, said support means including a cross-slide member having first and second carriages, said first carriage being fixedly mounted on said second axle, said second carriage being mounted for relative movement between said first carriage and said housing, said welding gun means further including a welding gun secured to and movable with said first carriage;
• and
• a second decoder means for measuring the angle of traverse of said first axle relative to said housing.