Abstract: A plasma arc torch both cutting and marking of metal workpieces includes a plasma nozzle having a plasma nozzle orifice through which an electric arc from an electrode and a stream of plasma gas are emitted toward a workpiece, and a liquid-injection shield cup that injects liquid tangentially inwardly to the arc and stream of plasma gas. A power supply is operable to selectively deliver electrical power to the electrode at either a low power level suitable for marking of a workpiece or a high power level suitable for workpiece cutting. The torch may be selectively operated to mark at the low power level, with a plasma marking gas being delivered to the plasma gas passage, or to cut at the high power level, with a plasma cutting gas being delivered to the plasma gas passage, and liquid being delivered to the liquid injection passage for both cutting and marking.

Abstract: A plasma arc torch both cutting and marking of metal workpieces includes a plasma nozzle having a plasma nozzle orifice through which an electric arc from an electrode and a stream of plasma gas are emitted toward a workpiece, and a liquid-injection shield cup that injects liquid tangentially inwardly to the arc and stream of plasma gas. A power supply is operable to selectively deliver electrical power to the electrode at either a low power level suitable for marking of a workpiece or a high power level suitable for workpiece cutting. The torch may be selectively operated to mark at the low power level, with a plasma marking gas being delivered to the plasma gas passage, or to cut at the high power level, with a plasma cutting gas being delivered to the plasma gas passage, and liquid being delivered to the liquid injection passage for both cutting and marking.

Abstract: A process for using a plasma arc torch is provided that includes operating a power source of the plasma arc torch to initiate an electric arc between an electrode of the plasma arc torch and a nozzle of the plasma arc torch at a starting arc current. A flow of argon-containing gas can be provided through the nozzle while the arc exists between the electrode and the nozzle, and the power source operated to cause the arc to extend out from the nozzle to a coating of insulation on a workpiece. The arc may ionize at least part of the argon-containing gas so as to burn through the insulation of the workpiece and attach the arc to metal of the workpiece. Thereafter, the flow of argon-containing gas can be halted and a flow of a different gas can be provided while increasing the arc current above the starting arc current.

Abstract: Embodiments of methods of controlling the shape of a cut on a workpiece using a plasma arc torch are provided. The methods may control the resultant cut angle and the shape of a top of the cut. The top of the cut can have either a sharp edge, or have a rounded lip. The radius of the rounded lip can be adjusted. The standoff distance defined between the nozzle of the plasma arc torch and the top surface of the workpiece contributes to defining the resultant cut angle and the shape of the top of the cut. In particular, increasing the standoff results in a greater radius and increases the cut angle and decreasing the standoff distance does the opposite. Additionally, the angle of inclination of the plasma arc torch can be used to compensate for a resultant cut angle so as to produce a desired cut angle.

Abstract: A method of marking underwater with a plasma arc torch is provided. The method includes surrounding a plasma arc produced by the plasma arc torch with a flow of gas. The flow of gas may be directed around and/or along the body of the plasma arc torch with an air curtain attachment. Directing the flow of gas in this manner generates a protective air curtain which substantially surrounds the plasma arc. A current between 8 and 35 amperes may be used to mark the workpiece. Thereafter, the workpiece may be cut using the same plasma arc torch with a current between 30 and 750 amperes. The same nozzle and rate of flow of gas may be used for both the marking and cutting operations. Additionally, the workpiece may be kept underwater throughout the marking and cutting operations.

Abstract: A plasma marking torch for marking metal workpieces with lines, numbers, or symbols, and which utilizes a non-cutting plasma gas such as argon, and a shield gas which comprises an air/water mist mixture. In one disclosed embodiment, the shield gas passes serially into contact with the electrode and the nozzle so as to efficiently cool the same, and it then passes through an annular orifice surrounding the bore of the nozzle to the workpiece. In another embodiment, provision is made for selectively operating the torch either in a cutting mode, or a marking mode.

Abstract: A metal cutting apparatus which comprises a longitudinally moveable gantry and a transversely moveable carriage which is mounted on the gantry. The carriage in turn mounts a laser cutting head and a plasma arc cutting head mounted in a parallel, side-by-side arrangement. The apparatus may thus be programmed to operate either the laser cutting head or the plasma arc cutting head as the gantry and carriage move in a predetermined path above the underlying workpiece. The laser generator is mounted in the gantry so that the beam is transported to the laser head with minimal bends and turns. The apparatus may also include a second carriage, which mounts a second laser cutting head and second plasma arc cutting head, so as to permit simultaneous cutting along two cut lines.

Abstract: A torch positioning apparatus controls a torch as it moves downward at a relatively rapid rate toward a work piece until it trips a proximity switch, causing the rate of travel of the torch to be slowed. The torch continues its travel until it strikes the work piece and stops, and the increase in the level of power required upon stopping is detected by a circuit which compares this increased power requirement with a power level previously measured and stored while the torch is moving, causing the direction of travel of the torch carriage to be reversed for a preset time so as to position the torch at the desired height above the work piece. A safety mechanism is included which shows the travel of the carriage in case the proximity switch fails.