TPT November 2013

Article

Polysoude SAS

Figure 12: Narrow Gap welding with robot

Use of a welding robot is also recommended for anything other than circular trajectories or where the industrial company wishes to acquire a more versatile tool. There are no particular considerations for solutions involving torches intended for applications up to 45mm. A retractable nozzle torch offers a multipurpose solution provided that electrode changing can be accepted as a non-automatable operation. For heavy wall thicknesses, torch weights and dimensions must be integrated and robots compatible with wrist loads of 10 to 50kg selected. The notion of trajectory remains linked to the profile of the torches which limits movements and implies studying torch positioning along the usual three axes. The use of a Narrow Gap torch renders the notion of automated preventive maintenance, such as electrode changing, somewhat illusory. The other approaches are specific to robot use and are to be addressed according to workpiece dimensions and the level of automation (gantry, multi-robot station, seam tracking, etc). Narrow Gap TIG welding is no longer a solution for exceptional circumstances. It is important to consider it whenever the thickness to be welded exceeds 30mm. An initial analysis is imperative to ascertain the potential benefit, verify the absence of notable contraindications and above all to choose the methodology and equipment best suited to the context. There are a multitude of solutions with a significant level of industrial maturity confirmed by numerous concrete examples.

The difficulties involved in implementing the welding procedures vary according to the chosen technique. The temptation to take a simplistic approach and skip a case-by- case assessment must, however, be avoided as there is no universal solution. Moreover, in terms of tools, the entire 30 to 300mm thickness range is covered with numerous variants and adaptation possibilities for special cases. For the welding process, knowledge and mastery of TIG are highly important and enable the technique to be popularised, with recourse in the event of difficulties. From the point of view of industrial companies, the implementation of a Narrow Gap application calls for a structured approach with marked steps. In parallel, corresponding approaches for machining facilities, tracking and traceability of materials and inspection techniques may need to be undertaken requiring validation steps close to those used in welding. All of these anticipatory measures are justified by the prospect of substantial gains compared with the use of more conventional techniques.

Polysoude SAS – France Email: info@polysoude.com Website: www.polysoude.com

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November 2013