Welding apparatus

Claim 1

IN A PORTABLE HAND GUN FOR WELDING A CURVED, FLEXIBLE ARTICLE TO A BASE MEMBER AND FOR MAINTAINING SUCH ARTICLE UNDER A PREDETERMINED DEGREE OF PRESSURE DURING THE WELDING OPERATION, SAID GUN COMPRISING A BARREL PORTION AND A GRIP PORTION, A SLIDABLE PLUNGER OF ELECTRICALLY-CONDUCTIVE MATERIAL CARRIED IN SAID BARREL AND SPRING-BIASED TO AN EXTENDED POSITION, A TRIGGER PIVOTED TO THE GRIP PORTION OF SAID GUN, SAID TRIGGER HAVING MEANS PROJECTING INTO SAID BARREL FOR MAINTAINING SAID PLUNGER IN A RETRACTED POSITION AGAINST THE ACTION OF THE BIASING MEANS ASSOCIATED THEREWITH, A CHUCK CARRIED ON THE FORWARD PORTION OF SAID PLUNGER AND DESIGNED TO RELEASABLY SUPPORT ONE END OF THE CURVED, FLEXIBLE ARTICLE TO BE WELDED, A TUBULAR EXTENSION ON SAID BARREL AND DESIGNED TO CONTACT SAID BASE MEMBER DURING THE WELDING OPERATION, PLUNGER STOP MEANS DISPOSED WITHIN SAID BARREL AND MANUALLY ADJUSTABLE IN POSITION AXIALLY THEREOF, WHEREBY AN AXIAL ADJUSTMENT OF SAID STOP MEANS DETERMINES THE FOREMOST POSITION ASSUMED BY SAID CHUCK WITHIN SAID TUBULAR BARREL EXTENSION WHEN SAID PLUNGER IS IN ITS EXTENDED CONDITION, AND A SWITCH ACTUATABLE BY A SELECTIVE MOVEMENT OF SAID TRIGGER, WHEREBY AN INITIAL MOVEMENT OF SAID TRIGGER WILL CAUSE SAID PLUNGER TO MOVE TO AN EXTENDED POSITION IN RESPONSE TO THE ACTION OF ITS BIASING MEANS IN WHICH POSITION BOTH THE OUTER END OF SAID BARREL EXTENSION AND THE REMAINING END OF SAID ARTICLE ARE BROUGHT INTO CONTACT WITH SAID BASE MEMBER AND SAID ARTICLE IS PLACED UNDER A DEGREE OF PRESSURE DETERMINED BY THE ADJUSTMENT OF SAID PLUNGER STOP MEANS WITH RESPECT TO THAT END OF SAID TUBULAR BARREL EXTENSION WHICH HAS BEEN BROUGHT INTO CONTACT WITH SAID BASE MEMBER, AND WHEREBY A FURTHER MOVEMENT OF SAID TRIGGER WILL ACTUATE SAID SWITCH FROM AN OPEN TO AN ELECTRICALLY CLOSED POSITION.