Abstract: A method and apparatus for registration of a seal to a perforation on a plastic bag include a drum for forming a seal on a continuous plastic film and a downstream perforator/cutting station for forming a perforation on the film with respect to the location of the seal. The perforation is properly registered to the seal by sensing the seal location directly, with a seal sensor located near the perforator/cutting station.

Abstract: An plasma cutter, including a power supply, a cutting torch (with a nozzle), a source of air and a valve, is disclosed. The cutting torch is connected to the two power source outputs (cathode and anode). Air is supplied to the nozzle through the valve from the air supply. In one position the valve allows air to flow from the air source to the nozzle. In a second position the valve prevents air from flowing from the air supply to the nozzle and also vents the nozzle and torch. The torch has a movable electrode and the nozzle is in a fixed position. The nozzle and electrode are each electrically connected to a different one of the power outputs. The electrode is biased (preferably by a spring) to be in contact with the nozzle. However, air flowing into the torch and electrode overcomes the bias and moves the electrode away from the nozzle. If the arc is absent and the user desires current, then the valve is moved to prevent air from flowing into the torch and to vent the torch.

Abstract: An inverter power supply for use with various voltage inputs is provided. The inverter power supply generally receives 208 VAC single-phase, 208 VAC three-phase, 230 VAC three-phase, 230 VAC single-phase, 460 VAC single-phase, or 460 VAC three-phase power and provides a DC output current for welding, heating or cutting applications. The power inverter circuit includes a first tank circuit and a second tank circuit which are configured in serial or parallel according to a particular voltage input. Dual contactor switches respond to control signals from an AC sense circuit in order to configure the inverter power supply for the appropriate voltage input. The dual contactors may be mechanically interlocked and driven off the DC power for the control board.

Abstract: An engine driven welding power supply is disclosed. The power supply produces a welding output having a plurality of volt-ampere curves. Each of the curves is associated with a selected current output and includes a slope over usable welding range. The magnitude of the slope over the usable welding range is dependent on the selected current output, particularly at a middle range of output currents. The power supply includes a AC generator that provides an AC signal. A rectifier rectifies the AC signals and provides a DC output. The DC output is provided to an output inductor that provides a smooth DC output. The V-A curves are produced by phase control in the rectifier.

Abstract: A welding power supply that includes a series resonant converter, including at least one switch and at least one capacitor is disclosed. The converter includes a switching circuit including an enable input. A voltage sensing circuit that determines the earliest safe switching time of the switch is provided. The safe switching time is the time that will prevent a peak voltage on the capacitor from exceeding a predetermined threshold for a next cycle of the converter. The voltage sensing circuit provides an enable signal to the enable input when the earliest switching time has passed, to enable the switching circuit. A pair of welding output terminals connected to the series resonant converter receives the output. A controller including a curve shaper, for providing a constant current output in the welding range is also disclosed. The controller also provides an adaptive hot start that provides varying amounts of energy in response to the welders skill.

Abstract: A welding power supply includes an ac generator with a field winding and a welding output winding. An electronic field controller receives current and voltage feedback from the welding output. This electronic field controller is connected to the field winding, controlling the current through this winding in such a way that the volt-ampere output curve at the welding output winding consists of a plurality of selected nominal output current curves, each of these curves including at least two breakpoints.

Abstract: A method and apparatus for arc welding, particularly starting an arc is disclosed. A welding power source that provides a welding current to an electrode and a workpiece includes a source of welding current having an inductor. The inductor and current source are connected to a pair of outputs, such as the output studs, and form a welding current path including the source of current, the output inductor, the outputs and the electrode and workpiece. A source of a high frequency voltage, such as a high frequency coupling coil is included in the welding current path. An arc starting circuit provides a controllable current path for current flow in the inductor prior to the application of high frequency voltage. The arc starting current path is not the welding current path.

Abstract: In accordance with the present invention a power supply for providing an ac/dc output to a load is disclosed. The power supply includes a first source of dc power and an inverter that provides an ac output to the load. A second source of dc power is provided and selectably connects the first and second sources of dc power in series with the load when the output current reverses. In one embodiment the power sources are connected in series with every output current reversal. The first source of dc power is controllable and the magnitude of the dc current is responsive to a current reference signal. A control circuit provides the current reference signal, wherein the current reference signal is pulsed immediately prior to the ac output reversing polarity. The first source of dc power source preferably includes a buck converter that is switched at a variable frequency, depending upon the desired output current.

Abstract: An apparatus and method are provided for detecting a formation or change in the consistency of a moving sheet material. The apparatus includes a radiation source, a radiation receiver, a support base for the sheet material, and a signal processor for producing a signal in response to the detection of a formation in the material. The apparatus may be modified to include moving or stationary support bases, and may be further modified to include structure for automatically positioning the source and receiver to optimize the detection of formations.

Abstract: An operator controllable transformer having a variable inductor with a control coil is provided. The transformer includes phase control circuitry to control the output of the transformer by phase controlling current flow in the control coil, thereby controlling the current provided to the load.

Abstract: An plasma cutter, including a power supply, a cutting torch (with a nozzle), a source of air and a valve, is disclosed. The cutting torch is connected to the two power source outputs (cathode and anode). Air is supplied to the nozzle through the valve from the air supply. In one position the valve allows air to flow from the air source to the nozzle. In a second position the valve prevents air from flowing from the air supply to the nozzle and also vents the nozzle and torch. The torch has a movable electrode and the nozzle is in a fixed position. The nozzle and electrode are each electrically connected to a different one of the power outputs. The electrode is biased (preferably by a spring) to be in contact with the nozzle. However, air flowing into the torch and electrode overcomes the bias and moves the electrode away from the nozzle. If the arc is absent and the user desires current, then the valve is moved to prevent air from flowing into the torch and to vent the torch.

Abstract: A method and apparatus for registration of a seal and perforation on a plastic bag include a drum for forming a seal on a continuous plastic film with respect to a registration mark on the film and a perforator/cutting station for forming a perforation on the film with respect to the location of the seal. This method and apparatus is used in a plastic bag making machine to produce bags of different lengths. A detector locates the registration mark printed on the film and the drum diameter may be adjusted to form the seal at a desired location on the film with respect to the registration mark. A seal detecting station locates the seal and a controller adjusts the speed of the perforator/cutting station to properly locate the perforation with respect to the seal and to maintain a desired skirt length.

Abstract: In accordance with the present invention a power supply for providing an ac/dc output to a load is disclosed. The power supply includes a first source of dc power and an inverter that provides an ac output to the load. A second source of dc power is provided and selectably connects the first and second sources of dc power in series with the load when the output current reverses. In one embodiment the power sources are connected in series with every output current reversal. The first source of dc power is controllable and the magnitude of the dc current is responsive to a current reference signal. A control circuit provides the current reference signal, wherein the current reference signal is pulsed immediately prior to the ac output reversing polarity. The first source of dc power source preferably includes a buck converter that is switched at a variable frequency, depending upon the desired output current.

Abstract: A method and apparatus for providing a welding current is disclosed. The power source is capable of receiving any input voltage over a wide range of input voltages and includes an input rectifier that rectifies the ac input into a dc signal. A dc voltage stage converts the dc signal to a desired dc voltage and an inverter inverts the dc signal into a second ac signal. An output transformer receives the second ac signal and provides a third ac signal that has a current magnitude suitable for welding. The welding current may be rectified and smoothed by an output inductor and an output rectifier. A controller provides control signals to the inverter and an auxiliary power controller that can receive a range of input voltages and provide a control power signal to the controller.