Abstract: A coolant tube and electrode are adapted to mate with each other to align the tube relative to the electrode during operation of the torch. Improved alignment ensures an adequate flow of coolant along an interior surface of the electrode. In one aspect, an elongated body of the coolant tube has a surface adapted to mate with the electrode. In another aspect, an elongated body of the electrode has a surface adapted to mate with the coolant tube. The surfaces of the tube and electrode may, for example, be flanges, tapered surfaces, contours, or steps.

Abstract: The invention is generally directed to a nozzle for a plasma torch, the nozzle having a rear portion that defines at least a portion of a plasma chamber and a front portion that includes a first end and a second end. The first end is adjacent the rear portion, and the second end defines a plasma exit portion. One or more fluid passageways are disposed within the front portion and extend from the first end to the second end. The fluid passageways have passageway exit portions that provide one or more discrete jets of a secondary fluid to surround a plasma jet that is ejected from the plasma exit portion. Features of the invention include faster cutting, thicker workpiece piercing capability, reduced noise, improved arc stability, and increased consumable life, all of which improve productivity associated with plasma arc torch workpiece processing.

Abstract: A method and apparatus for controlling a gas supply to a plasma arc torch uses a proportional control solenoid valve positioned adjacent the torch to manipulate the gas flow to the torch, thereby extending electrode life during arc transfer and shutdown. Swirl ring design can be simplified and gas supply and distribution systems become less complicated. The invention also allows manipulation of shield gas flow to reduce divot formation when making interior cuts. The system can be controlled with a digital signal processor utilizing a feedback loop from a sensor.

Abstract: A coolant tube and electrode are adapted to mate with each other to align the tube relative to the electrode during operation of the torch. Improved alignment ensures an adequate flow of coolant along an interior surface of the electrode. In one aspect, an elongated body of the coolant tube has a surface adapted to mate with the electrode. In another aspect, an elongated body of the electrode has a surface adapted to mate with the coolant tube. The surfaces of the tube and electrode may, for example, be flanges, tapered surfaces, contours, or steps.

Abstract: A coolant tube and electrode are adapted to mate with each other to align the tube relative to the electrode during operation of the torch. Improved alignment ensures an adequate flow of coolant along an interior surface of the electrode. In one aspect, an elongated body of the coolant tube has a surface adapted to mate with the electrode. In another aspect, an elongated body of the electrode has a surface adapted to mate with the coolant tube. The surfaces of the tube and electrode may, for example, be flanges, tapered surfaces, contours, or steps.

Abstract: A display (200) includes a slanted fringe volume hologram (206) or other optical element that steers light that passes into and out of the display (200) so as to provide angular separation between unmodulated scattered light and modulated reflected light. As a result of the angular separation the effective contrast of the display (200) is improved. By placing the slanted fringe volume hologram (206) below a front polarizer of the display a further reduction in the amount of unmodulated scatter light is achieved. The slanted fringe volume hologram is preferably a hologram of a diffusive object (328), and consequently exhibits a degree of light diffusion that results in a viewing zone of an appreciable angular extent.

Abstract: A display (200) includes a slanted fringe volume hologram (206) or other optical element that steers light that passes into and out of the display (200) so as to provide angular separation between unmodulated scattered light and modulated reflected light. As a result of the angular separation the effective contrast of the display (200) is improved. By placing the slanted fringe volume hologram (206) below a front polarizer of the display a further reduction in the amount of unmodulated scatter light is achieved. The slanted fringe volume hologram is preferably a hologram of a diffusive object (328), and consequently exhibits a degree of light diffusion that results in a viewing zone of an appreciable angular extent.

Abstract: A flow of ionizable gas is provided to a shielded plasma arc torch which includes an electrode, a translatable nozzle, a nozzle retainer, and a shield. After passing through a heat exchanger to cool the electrode, the gas flow enters an annular chamber where the flow is divided into three subflows. A first subflow enters a plasma chamber formed by the electrode, the nozzle, and a swirl ring to pressurize the plasma chamber and support a plasma arc. The second subflow passes serially through apertures in the nozzle retainer and the shield to shield the plasma arc. The remaining flow is vented to ambient. Accordingly, a single gas flow may be employed to independently support multiple torch operating requirements.

Abstract: A safety circuit is utilized in a blow forward contact start plasma arc torch to extinguish the current to the torch upon determination of an unsafe operating condition. The torch includes a torch body, an electrode and a translatable conductive nozzle biased into contact with the electrode. The safety circuit receives a reference signal a signal indicative of the arc voltage and a mode status signal. The torch current is extinguished when the signal indicative of the arc voltage is less than the reference signal and the mode status signal indicates the torch is operating in the transferred arc mode.

Abstract: A translatable nozzle is supported in a contact start plasma arc torch at an aft end by a swirl ring and at a longitudinally spaced forward end by an insulative bearing member of a nozzle retainer. The nozzle is biased into contact with an electrode by a compliant spring element. A pilot arc is formed by first passing current through the electrode and nozzle. Upon pressurization of a plasma chamber formed therebetween, the nozzle is translated forward, compressing the spring element and initiating the pilot arc. The spring element may be maintained integrally with the nozzle to facilitate removal and replacement of the spring element with the consumable nozzle.