No abstract available

[en] Experimental approaches were performed for TIG arcs in order to understand the effects of a constricted nozzle on plasma properties and heat transfer. This paper reports current density and heat flux distributions at the anode surface and temperature distributions of the arc plasma for pure argon arc. The results show that the current density and heat flux near the centre of the arc really increased due to a cooling effect of a high speed gas flow inside a constricted nozzle and the arc constriction was confirmed by measurements of temperature distribution

[en] The MG process with pulse width modulated current and cold wire filler is suitable mainly for the production of high-quality welded joints. Three orbital welding heads adapted to requirements of the nuclear power station constructor have been designed for the mechanized forced circular seam welding of tubes. They differ in respect of their scope, in the structural height and in the number of the motor - controllable functions and the maximal values of the parameters defined by the functions. (orig.)

[en] In a sensitivity study the influence of initial and boundary welding parameters upon the spatial and temporal temperature distribution in a work-piece during dry hyperbaric GTA-welding is investigated. It will be shown that at constant arc current a variation of pressure (1-60 bar), arc length (3-10 mm), welding speed (1-2.5 mm/s) or the initial temperature (20-200deg C) of the work-piece to some extend significantly influences the size of melt and heat affected zone as well as the maximum temperature and cooling behaviour of the work-piece; compared to this no mentionable effects of shielding gas temperature (20-300deg C) or flow rate (10-500 dm_N³/min) on the thermal condition of the work-piece can be recognized. The discovered relationships have been approximated by simple correlations, which can be used for parameter optimization and process control. (orig.) With 33 figs., 4 tabs

[en] For automated welding of small-bore pipes (d < 100) adequate welding devices, i.e. clamp-type welding heads, are being used. For a perfect weld the functions of the welding device must be reproducible. The welding parameters, once determined, must be adhered to with the utmost accuracy in order to limit the failure rate to the desired level of 1% under various operating conditions. The TIG welding process with pulsed electric arc has proved to be of special advantage for producing such welds. Sufficient penetration can be reached due to the controlled heat input and heat profile (fusion and solidification phase can be programmed) leading to secure root fusion and root configuration. Besides, the process can be used for all fixed positions. The equipment technology and practical experiences are described. (orig.)

[en] The TIG (Tungsten-inert gas) orbital welding technique is applied in all areas of pipe welding. The process is mainly used for austenitic and ferritic materials but also for materials like aluminium, nickel, and titanium alloys are commonly welded according to this technique. Thin-walled as well as thick-walled pipes are welded economically. The application of orbital welding is of particular interest in the area of maintenance of thick-walled pipes that is described in this article. (orig.)

[en] The system of automatic control of tungsten electrode position with the help of electromechanical detector contacting with the profile welded was designed and investigated. Stabilization system that provided for tungsten electrode perpendicularity was studied for accuracy and reliability. The system of automatic control ensured stability of weld formation during shaped profile welding

[en] This report provides the design basis and justification for a closure welding technique using the manual Gas Tungsten Are Welding (GTAW) process. Other aspects affecting closure of Canister S00645, e.g., shielding, facility and administrative requirements, etc., are addressed elsewhere

[en] The welding of fixed tubes is mostly all position welding in restricted places, accordingly much skill is required. The automation of welding is necessary because of the requirement for the reliability of welded joints, the difficulty of securing skilled workers, and welding quality. The development and production of the automatic welders for TIG welding of tubes have been carried out by Mitsubishi Electric Corp., and the application to various purposes was attempted. The TIG welding for the automatic welding of tubes is advantageous, because backside bead can be formed stably, spatter does not arise, welding is stable for every metal, and the mechanism of the automatic welders is simple. But it is not suitable for the welding of zinc-plated tubes, and the rate of deposition is relatively small. It is applied to the welding of boiler tubes, nuclear energy equipments and pipings, chemical equipments and pipings, and aluminum pipings. The specifications and the construction of the TIG tube welders are shown. The preparation of joints and the control of welding conditions are important for guaranteeing the welding results in automatic welding, therefore sufficient consultation with welder makers about these points is required. The welding defects apt to arise are the bad form of backside beads, blowholes, and the insufficient melting of intermediate layers, and the countermeasures to them must be taken. (Kako, I.)

[en] The total field of plasma technology - excluding fusion and lasers - was subdivided into six areas: Welding, Cutting, Melting; Switch Gear Devices; Light Production; High Pressure Plasma Processing; Low Pressure Plasma Processing; and Pulsed Power. In each area the authors asked the experts for the social and economical relevance of the discipline; the relevance of the plasma for the field; and indispensable and promising tasks in research and development. Summarizing all results it can be stated that plasma technology is a key technology, which influences resp. controls well established markets. Its high innovation potential promises remarkable growth rates in various high tech applications. Precondition for a fast and successful development is intensive application oriented basic research in all areas of Gaseous Electronics, Central points of interest are - Modelling of realistic discharges; - Diagnostics of real plasmas; - Electrode phenomena and plasma wall interaction; Dynamics and kinetics of non-equilibrium system; and - Fast varying systems