
As part of this research project, six narrow gap welding processes were investigated, in each of which submerged arc, MIG/MAG and TIG were used. Where possible, welding was carried out with different heat input and/or …
As part of this research project, six narrow gap welding processes were investigated, in each of which submerged arc, MIG/MAG and TIG were used. Where possible, welding was carried out with different heat input and/or, if suitable, in different positions. Pipes made of 20 MnMoNi 55 with a wall thickness of 45 mm were used as the base material, with a joint depth of 80 mm simulated by means of attached rings. In three of the cases presented, austenitic pipes with a wall thickness of 40 or 80 mm were used. To summarise, it can be stated that the individual processes are susceptible to the occurrence of weld seam defects to varying degrees.
The submerged arc welding process had the lowest defect rate. In the gas-shielded welding methods, pores can occur due to turbulence in the shielding gas cover. The correct distance between the wire and the joint flank is important in order to avoid bonding defects with regard to non-oscillating wire electrodes. With oscillating arcs, it is very important to maintain the correct oscillation amplitude. Welding with two flux-cored electrodes in a tandem arrangement achieved the highest deposition rate, ahead of submerged arc and MAG welding with an oscillating current contact tube. Some processes lost advantages due to a reduced duty cycle caused by non-productive times. The contraction of the welding gap due to shrinkage was limited in all cases and could be compensated for by widening the joints upwards via the opening angle. With one exception, the quality properties specified for the weld metal and the heat-affected zone were achieved in all processes. The best toughness values were found where the weld was made up of individual beads that were not oscillated. With regard to the economic efficiency of the individual methods, the results were primarily determined by the joint volume. TIG narrow gap welding cannot compete with the other welding methods in terms of welding costs. However, this method produces particularly high-quality seams and is the only one of the methods analysed that can be used in all positions. A comparison of all the properties shows that almost all the methods analysed are ready for use in industrial practice. However, detailed improvements are required for some of them. STUDIENGESELLSCHSAFT FÜR ANWENDUNGSTECHNIK VON EISEN UND STAHL e.V.

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P 100 - Development of characteristic values for the production of cold rolled profiles from the point of view of economical production of dimensionally accurate profiles Cold profiling using the roll forming process is a forming process that has been used industrially for over half a century. It allows the production of cold-formed profiles with consistent and high dimensional accuracy, some with sharp-edged bends, many curved sections, complicated double folds, with - if desired - targeted work hardening of the starting material and finally the combination of profile shaping with further processing steps such as punching, beading and bending. Although the diverse requirements and the general technical development of mechanical engineering have led to a wide variety of roll forming systems over the course of time, the technology of roll forming is still largely based on practical experience. This applies both to the dimensioning of production facilities and to the design of forming tools. This unsatisfactory situation can probably be explained essentially by the fact that the entire process - in addition to the rather difficult geometric relationships of forming - is governed by numerous working conditions which influence each other. For this reason, the Technical Committee of the German Cold Forming Association has been working closely with a well-known plant manufacturer for several years on the development and dimensioning of a machine and drive concept for research purposes. A machine and control technology solution was developed and realised which for the first time makes it possible to empirically investigate the interactions between the parameters of the production process and the properties of the product in a reproducible manner. This research work was carried out on behalf of the Studiengesellschaft für Anwendungstechnik von Eisen und Stahl e.V. by Prof. Dr.-Ing. D. Schmoeckel, Institute for Forming Technology at Darmstadt Technical University. In addition to confirming some of the results of earlier investigations, new findings of practical relevance were obtained. This applies in particular to the experiments on slip reduction, which resulted in a drastic saving in the energy used, and on the relationship between the quality of the finished product and the selected forming strategy. These results represent a step towards a better understanding of the complex manufacturing process, but at the same time demonstrate the need for further intensive efforts to conduct in-depth research into roll forming technology. The research project was funded by the Federal Ministry of Research and Technology (BMFT) and was supervised by Kernforschungsanlage Jülich GmbH (KFA) as the project sponsor for the raw materials research programme. STUDIENGESELLSCHAFT FÜR ANWENDUNGSTECHNIK VON EISEN UND STAHL e.V. Publication: 1986 Authors: Prof. Dr.-Ing. D. Schmoeckel, Dipl.-Wirtsch.-Ing. U. Eichler
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