Robot welding gun unit

A robot welding gun which is a welding gun mounted on a robot arm of a robot comprising:

• a welding gun mounting bracket secured to the robot arm so as to move in conjunction with the robot arm;
• a gun body that includes a frame member, which has a front end and a rear end, and mounting means between said front and rear ends for slidably mounting said frame member of said gun body to said mounting bracket to facilitate forward and rearward sliding of said gun body, said gun body including a fixed arm which is fixed relative to said frame member and extends forwardly from said front end, said fixed arm terminating at a tip end which includes a rearward projecting first welding electrode, said gun body further including a slidable rod which is slidably mounted to said frame member, extends forwardly toward said tip end of said fixed arm, and includes a forward projecting second welding electrode, said gun body further including means for moving said slidable rod forwardly to clamp an object to be welded between said first and second welding electrodes and rearwardly to release the object;
• and
• an adjustment unit which is attached to said mounting bracket and includes a forward projecting adjustment rod with a distal end and a proximal end and adjusting auxiliary means for detecting wear to said first electrode, said adjustment unit including reversible actuating means engaged with said proximal end of said adjustment rod for selectively driving said adjustment rod in response to wear detected by said adjusting auxiliary means, said adjustment rod drivingly interconnected to said fixed arm at all times so that said fixed arm is reversibly driven both forwardly and rearwardly along a predetermined path to a selected position therealong in response to said driving of said adjustment rod and said fixed arm is forwardly and rearwardly restrained by said rod in said selected position when said rod is stopped.

A method for positioning electrodes on a robotic welding gun comprising the steps of,

• providing a welding gun including a frame, an adjustment means connected to said frame for moving a first arm fixed to said adjustment means, a first welding electrode on a distal end of said first arm, said first welding electrode having a tip at a predetermined position, a second arm with a second welding electrode at a distal end thereof, a motive means fixed to said frame for moving said second welding electrode into contact with an object to be welded thereby clamping the object to be welded between said first and second welding electrodes when said first and second electrodes are in an activated state;
• positioning a sensor near said first electrode when said first and second electrodes are in a deactivated state;
• sensing wear on said first welding electrode using said sensor;
• and
• repositioning said tip of said first welding electrode to compensate for wear thereon by activating said adjustment means, thereby adjusting said first arm and said tip of said first welding electrode so as to maintain said tip at said predetermined position without reorienting the entire robotic welding gun.