2004

Karhu, Miikka; Jokinen, Tommi; Kujanpää, Veli

During the work of this task, a closed loop feed-back control system was developed and connected to the EB-welding machine of VTT. Research and development procedure was dealt in two stages. At the first stage a proper measurement system was developed and built up. At that stage preliminary welding tests were carried out in order to plot sensitivity of the process and to get confirmation of functionality of the measurement system. The actions of the second stage were based on the promising results of preliminary welding tests carried out at the stage one. During the stage two, the measurement system was upgraded with building a closed loop adaptive control connection to the system. As a final part of stage two, bead-on-plate welding tests at flat position were carried out to clarify the performance and usability of the developed control system. The test pieces were austenitic stainless steel plates (thicknesses between 8 and 12mm) which thickness was whether linearly increased or decreased in ratio of 1:40 in the middle part of the test piece. An increment and a decrement of thickness was chosen to be altered within 2 mm, which will simulate possible thickness alteration of the root face, resulted from manufacturing of very large-size work piece. As a whole, the carried welding tests gave promising results on the functionality of the control system, as well as the applicability of the concept itself. Some further work is recommended though, mainly concerning the improvement of reliability of the system and welding experiments with a longer weld length and at different welding positions.