Abstract: A power supply is disclosed for both arc welding and plasma cutting. The power supply includes an A.C. power source, a transformer having a primary winding receiving power from the A.C. power source and a secondary winding. Power in the secondary winding is rectified by rectifier to provide a first output suitable for arc welding and a second output suitable for plasma cutting. A switch connected to the rectifier selects between the two outputs. Conventional power supplies employ an inductance for stabilizing the current in the plasma cutting power supply. According to another aspect of the invention, the power supply includes a circuit path in parallel to the inductance for passing additional current to the torch so that the open circuit voltage applied to the inductance required for sustaining the arc is reduced.

Abstract: The housing of the cutting torch power supply has an opening and a drawer which can be slid into and out of the opening. The back wall of the drawer carries a connector plug adapted for connection to the torch connectors and connections to a gas source, and a power source in the power supply. When the drawer extends out of the opening, the connector plug is accessible for changing connectors. The drawer may also be entirely removed from the housing so that the connector plug can be replaced. The above feature enables the power supply to be conveniently used for supplying power and gas to torches which have cables with different types of gas and power connectors. When the drawer is in a closed position, power is supplied to the torch. When the drawer is away from the closed position, a switch is activated to cut off power to the torch to prevent shock hazard.

Abstract: The voltage between a work instrument and a workpiece varies with the distance between them. A microcoded controller is used to compare the voltage between the work instrument and the workpiece when the instrument moves relative to the workpiece, to generate a correction signal. The correction signal is the sum of a proportional term, a derivative term and an integral term. A servo means responds to the correction signal to correct the distance between the work instrument and the work piece so as to maintain the voltage between them at a set level. A battery-backed memory is used to store crucial parameters necessary for operating the automatic control system to prevent loss of the parameters from the controller memory caused by power interruptions. A stepper motor operating in either the full of half step mode may be used to move the work instrument away from or towards the work piece in response to the correction signal.

Abstract: The optical tracker of this invention is for tracking a boundary on an illuminated surface where the reflectivity of the surface changes at the boundary. In the preferred embodiment the optical tracker includes an optic foot which rides on the surface to be tracked. The optic foot comprises a housing with two channels for receiving a transmitter optical fiber and the receiver optical fiber. The two channels converge to form an opening in the housing which faces the surface to be tracked. Light supplied by the transmitter optical fiber illuminates the portion of the surface underneath the opening and the reflected light from such portion of the surface enters the receiver optical fiber which transmits the light to a detecting means for locating and tracking the boundary on the surface. In the preferred embodiment the receiver optical fiber is oriented substantially normal to the surface and the transmitter optical fiber substantially at 60 degrees thereto to reduce dynamic range.

Abstract: The optical tracker of this invention tracks a boundary on the surface where the light reflectivity of the surface changes at the boundary. The optical tracker includes a sensing means for sensing light reflected from an elongated portion of the surface defining a window. When the sensing means is moved over the surface it will receive consecutively light reflected from a sequence of windows that ir passes over and generates a set of electrical signals indicative of the intensity of light reflected from locations along the length of the window. A microprocessor control means derives from the signals provided by the sensing means secondary sets of signals useful for serving as a template and for finding the boundary when the window includes a selected portion of the boundary. The microprocessor control means can be activated to record a secondary set of signals as a template.

Abstract: A seam welding apparatus is provided which automatically senses and adjusts the position of a welding torch in triaxial X, Y and Z directions and controls the position so as to maintain a predetermined position of the torch with respect to an irregularly shaped workpiece such as elliptical shapes. The apparatus also provides for continuously sensing and adjusting the surface speed of the workpiece so as to maintain a predetermined constant speed. A slope/speed sensor is also provided for sensing surface speed and slope of the workpiece. A method of continuously sensing triaxial position and surface speed of the workpiece adjacent the torch and adjusting the position of the torch and speed of the workpiece so as to maintain a desired position and speed is also provided.

Abstract: A signal conditioning circuit for providing a DC voltage to an arc voltage controller for controlling the length of an AC arc of a gas tungsten arc welder. Specifically, a first control circuit is employed which charges to a first value by a signal of a given polarity of one cycle of the AC arc for providing a DC voltage and an additional control circuit is employed for rapidly discharging the first control circuit when the maximum absolute amplitude of a signal of a given polarity of a subsequent cycle of the AC arc is less than the DC voltage provided by the first control circuit. The first control circuit is charged to a higher second value when the maximum absolute amplitude of a signal of a given polarity of a subsequent cycle of the AC arc is greater than the DC voltage provided by the first control circuit.