Electrical control for friction welding

Claim 1

IN COMBINATION WITH A FRICTION WELDER INCLUDING A VOLTAGE-RESPONSIVE HYDRAULIC PRESSURE REGULATING VALVE FOR ELECTRICALLY CONTROLLING THE THRUST PRESSURE APPLIED TO THE OBJECTS BEING WELDED, A CONTROL SYSTEM FOR SUPPLYING A SERIES OF DIRECT-CURRENT VOLTAGES OF PROPER VALUES AND IN A PROPER TIME SEQUENCE DURING BUILD-UP PRE-HEATING AND FORGING PHASE OF THE WELDING CYCLE NECESSARY FOR OPTIMUM PRESSURE OPERATION OF THE WELDER, SAID SYSTEM INCLUDING A SOURCE OF ALTERNATING VOLTAGE, TWO PRESET TRANSFORMERS AND A FULL-WAVE RECTIFIER BRIDGE HAVING TERMINALS SEPARATELY CONNECTED TO SAID A.C. SOURCE THROUGH RESPECTIVE ONES OF SAID TWO TRANSFORMERS AND HAVING ITS D.C. VOLTAGE OUTPUT APPLIED TO THE VALVE AT SEPARATE TIMES BY THREE DISTINCT CIRCUITS, THE FIRST ONE CONSISTING OF A SERIES ADJUSTABLE RESISTOR CONNECTING THE VALVE TO THE D.C. TERMINALS OF THE BRIDGE, THE SECOND CIRCUIT CONSISTING OF A VOLTAGE DIVIDER CONNECTED ACROSS THE D.C. TERMINAL OF THE BRIDGE WITH THE VALVE CONNECTED IN TURN ACROSS THE VARIABLE CONNECTION OF THE DIVIDER AND ONE END THEREOF THE VARIABLE CONNECCIRCUIT CONSISTING OF A DIRECT CONNECTION OF THE VALVE ACROSS THE D.C. TERMINALS OF THE BRIDGE.