Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Process improvement for multipass welding in boiler equipment manufacturing

The present project aimed at the development of an automatic system for MIG multipass welding in pressure vessel manufacturing, and generally speaking, for all those applications where multipass welding is required. It was also intended to study different welding sequences in order to reduce residual stresses, and advanced new materials, in order to avoid post-welding heat treatments in pressure vessel manufacturing. The results obtained on new materials are a start point for introducing MIG/MAG welding in pressure vessel fabrication. Chemical compositions of 8MnNimo y 2,25 Cr1Mo steels have been improved for MIG/MAG welding. In the case of the first material, it is possible to avoid the post-welding heat treatment .Results have been obtained both on the weld quality and seam geometry according to the gas, wire and welding parameters used. On the other hand, the welding sequence has been obtained in order to minimise the residual stresses. The multipass welding algorithms, developed by the users, have been included and validated within the control software, and validated. These criteria include the welding rectifier programming parameters, welding torch orientation and position related to the part edge, and the quality ranges for the seam's supervision. There is available a quality register capable of monitoring, supervising and registering the welding session, in real time. As an additional functionality, this software is able to calculate costs and generate reports. This working tool was found of great interest during the test bed phase: both for setting up the welding rectifier with the robot controller and as a welding session register. There is currently a prototype system for the welding process. This prototype has been used during the user test beds. It consists of an articulated robot integrated with a triaxial manipulator, with an optical sensor on the welding torch.


Miguel DORRONSORO, (Manufacturing Process Department Manager)
Tel.: +34-4-4522266
Fax: +34-4-4522330