Abstract: A method of joining together two relatively thin work pieces by arc welding is disclosed. The work pieces are rotated relative to a welding electrode so that the welding electrode is moved at relatively high speed over a path of contact between the work pieces where the weld is to be made. The power density at the work pieces is controlled so that it is necessary to make several passes of the electrode over the path of contact between the work pieces to make the weld. This welding procedure produces a weld of high quality without the use of complex current programming which is required when using conventional arc welding procedures.

Abstract: A method of arc welding is disclosed. Specifically, a method of pulsed DC arc welding is disclosed wherein the pulse width of the current pulses are modulated to maintain a constant time averaged power flow to the work pieces being welded. This method of arc welding is especially useful with a type of pulsed DC arc welding wherein the ratio of peak current to maintenance current is maintained at a selected high value and the current is cycled in a time duration whereby oxides on the surface of the work pieces are dissipated as the weld is made. When used with this type of pulsed DC arc welding the present method is especially suited for fluxless welding of aluminum work pieces, such as thin wall aluminum tubing used in making heat exchangers for air conditioning systems.

Abstract: A feedback control system for a pulsed direct current (DC) arc welding system is disclosed wherein the duty cycle of current pulses supplied by a power supply is controlled in response to resistance sensed at the arc gap of the system. The circuit comprises a voltage sensor, a high-low regulator, and a pulse width signal generator. The voltage sensor senses the voltage drop across the arc gap. This voltage is directly proportional to the resistance at the arc gap. The high-low regulator responds to the sensed voltage to generate an output signal when the voltage drop across the arc gap exceeds a high limit or is below a low limit. This output signal alters the control signal from the pulse width signal generator which controls the arc welding system power supply.

Abstract: Apparatus and a method for controlling the operation of a fin winding machine. Various motor drives are utilized to regulate the speed of rotation of a heat exchange tube upon which fin is wrapped to regulate the speed of rotation of forming wheels for bending the fin to the appropriate configuration and to regulate the speed of rotation of slitter wheels for perforating the fin prior to bending. Sensing means are provided for determining the length of the fin strip within various segments along a fin route such that the motor speeds are all adjusted to maintain the desired amount of fin strip. Tension means are provided for maintaining constant tension of the fin strip regardless of the length of the fin strip in the appropriate segment. The various sensing means are cascaded such that a change in speed of one motor may affect a change in speed of another motor.