Resistance welding machine

Claim 1

A RESISTANCE WELDING MACHINE, INCLUDING A POWER SUPPLY UNIT FOR FIRING SAID MACHINE AND A HEAD ADPTED TO UNIFORMLY AND ACCURATELY POSITION AN ELECTRODE THROUGHOUT EACH WELDING OPERATION SOLELY BY MOTOR AND TO ACU CURATELY CONTROL THE PRESSURE EXERTED BY ITS ELECTRODES AT ALL TIMES ON THE WORK PIECE BEING WELDED, COMPRISING: (A) A FIRST ELECTRODE MOUNTED ON A FIRST ELECTRODE HOLDER; (B) A SECOND ELECTRODE MOUNTED ON A SECOND ELECTRODE HOLDER WITH THE WORKING TIPS OF SAID ELECTRODES BEING IN ALIGNMENT WITH EACH OTHER; (C) A FRAME HAVING SAID SECOND ELECTRODE HOLDER HOLDER MOUNTED THEREON, SAID FRAME BEING MOUNTED IN SAID HEAD FOR MOVEMENT TOWARD SAID FIRST ELECTRODE TO POSITION SAID SECOND ELECTRODE HOLDER ADJACENT SAID FIRST ELECTRODE HOLDER WHEREBY THE WORKING TIPS OF SAID ELECTRODES CONTACT THE WORK PIECE BEING WELDED, (D) SPRING MEANS MOUNTED ON SAID FRAME FOR CONTROLLING THE FIRING OF SAID WELDING MACHINE BY SAID POWER SUPPLY UNIT, SAID SPRING MEANS BEING CONNECTED TO SAID SECOND ELECTRODE HOLDER FOR BIASING IT TOWARD SAID FIRST ELECTRODE HOLDER WITH A FORCE WHICH IS EXCEEDED WHEN THE CONTACT PRESSURE OF SAID ELECTRODES ON SAID WORK PIECE REACHES A PREDETERMINED VALUE; (E) SCREW MEANS CONNECTED TO SAID FRAME FOR POSITIONING SAID FRAME RELATIVE TO SAID FIRST ELECTRODE HOLDER; (F) MOTOR SYSTEM MEANS FOR OPERATING SAID SCREW MEANS, SAID MOTOR SYSTEM MEANS INCLUDING BRAKING MEANS FOR STOPPING SAID SCREW MEANS INSTANTANEOUSLY WHEN THE CONTACT PRESSURE OF THE ELECTRODES ON SAID WORK PIECE REACHES SAID PREDETERMINED VALUE; AND (G) CONTROL MEANS ACTUATED BY SAID SECOND ELECTRODE FOR ACTUATING SAID BRAKING MEANS AND FIRING SAID WELDING MACHINE WHEN SAID CONTACT PRESSURE REACHES SAID PREDETERMINED VALUE.