Variable-pitch spot welding gun assembly for a welding robot

A variable-pitch spot welding gun assembly for a welding robot, comprising;

• a base means directly fixed to a robot wrist of the robot;
• an electrical transformer means, fixedly attached to said base means at a portion as near as possible to an axis of motion of said robot wrist, for transforming an electric primary voltage into an electric secondary voltage necessary to spot-welding, wherein said electric transformer means comprises first and second electric transformers fixedly disposed with a fixed space therebetween along a predetermined axis;
• a fixed spot welding gun attached to said base means and separated from said electrical transformer means, said first electric transformer being connected to said fixed spot welding gun;
• a movable spot welding gun movably mounted on said base means and movable relative to said fixed spot welding gun along said predetermined axis to adjust a pitch therebetween, said second electric transformer being connected to said movable spot welding gun;
• and
• an electric secondary flexible conductor means electrically connecting said fixed and movable spot welding guns to said electrical transformer means.