Abstract: A welding management apparatus for use with a tube production machine. A workpiece fed from a roll of metal strip is formed in a tubular formation having side surfaces opposite to each other. An upsetting pressure is applied to joint the opposite side surfaces of the workpiece at a jointing point. A high frequency power is supplied to the workpiece to weld the opposite side surfaces at the jointing point so as to produce a metal tube member. The welding management apparatus comprises a camera positioned to have a visual field including the jointing point for producing a video signal indicative of an image including an area luminous with a pre-arc produced in the visual field. An image processor converts the video signal into a luminance distribution pattern. An inference unit is provided for inferring a defective welding condition based upon the luminance distribution pattern. The inference unit includes an alarm unit for producing an alarm when a defective welding condition is inferred.

Abstract: A welding management apparatus for use with a tube production machine adapted to form a workpiece fed from a roll of metal strip in a tubular formation having side surfaces opposite to each other, provide an upsetting pressure to butt the opposite side surfaces of the workpiece at a jointing point, and supply a high frequency power to the workpiece to weld the opposite side surfaces at a welding point so as to produce a metal tube. The welding management apparatus comprises a camera positioned to have a visual field including the jointing and welding points for producing a video signal indicative of an image of the visual field. The video signal is converted into a luminance distribution pattern used in controlling the high frequency power to the workpiece.

Abstract: In a method for processing nitrogen oxide, nitrogen oxide is reacted with hydrogen azide. Oxygen and/or plasma is utilized to accelerate the reaction between nitrogen oxide and hydrogen azide. An apparatus for use in performing the nitrogen oxide processing method includes a reaction case in which an aqueous solution containing hydrogen azide is provided. Nitrogen oxide containing gas is introduced into the reaction case for reacting nitrogen oxide with hydrogen azide to reduce nitrogen oxide. A plasma generating unit may be provided for feeding plasma into the nitrogen oxide contained gas.

Abstract: A welding management apparatus for use with a tube production machine. A workpiece fed from a roll of metal strip is formed in a tubular formation having side surfaces opposite to each other. An upsetting pressure is applied to joint the opposite side surfaces of the workpiece at a jointing point. A high frequency power is supplied to the workpiece to weld the opposite side surfaces at the jointing point so as to produce a metal tube member. The welding management apparatus comprises a camera positioned to have a visual field including the jointing point for producing a video signal indicative of an image including an area luminous with a pre-arc produced in the visual field. An image processor converts the video signal into a luminance distribution pattern. An inference unit is provided for inferring a defective welding condition based upon the luminance distribution pattern. The inference unit includes an alarm unit for producing an alarm when a defective welding condition is inferred.

Abstract: A high frequency welding system for tubular members applies high frequency current I to the gap for creating an alternating field. According to magnetic flux of the alternating field, an opposed current i is generated in a conductive portion of the welding apparatus. In close proximity, inductance is effected between the welding current I and the response current i. An output circuit is provided for generating high frequency current for establishing a welding heat with suppression of ripple current at the output. The welding processing is observed by a CCD camera which is in communication with an image processing portion for analyzing image data for determining welding conditions. A signal from the image processing portion is output to a monitoring portion which continuously monitors welding operation and activates an alarm if welding conditions exceed predetermined values.

Abstract: A method of measuring an effective heating power applied to a workpiece at a position to be heated by a high frequency heating apparatus having a source of high frequency AC power connected to a resonant circuits having a supply of high frequency AC power from the source for applying a high frequency AC power to the workpiece. An effective power P.sub.HF for the power supplied to the resonance circuit is measured. An effective value I.sub.t for the current sensed in the resonance circuit is measured. A power loss W produced in components following the source is calculated as a function of the measured effective value I.sub.t. The effective heating power Pw is calculated as Pw=P.sub.HF -W. In another aspect of the invention, the calculated effective heating power Pw is compared with a target value. The power to the resonance circuit is controlled in a direction zeroing the difference between the calculated effective heating power and the target value.

Abstract: An induction heating apparatus for utilizing electromagnetic induction to heat a workpiece. The apparatus includes a pair of heating coil units disposed in spaced-parallel relation to permit transportion of the workpiece between the heating coil units. Each of the heating coil units includes a main heating coil and an auxiliary heating coil disposed at a position adjacent to the main heating coil. The main heating coil has a plurality of spaced-parallel transverse conductors connected in series and produces magnetic field crossing the workpiece, causing heating when supplied with a high- or intermediate-frequency alternating current. The auxiliary heating coil includes a pair of series connected longitudinal conductors placed at positions facing to the workpiece at a small distance inside from the respective opposite side edges of the workpiece.