Improvement of transmission shafts used in hot water boilers

In improving the mechanical efficiency of the boilers, due to the increasing material costs and environmental concerns, the engineers are taking on more and more duties. The wall thicknesses of the boiler materials formed according to the thermal strength calculations are determined according to the mechanical strength formed by the alignment of the transmission shafts used. Therefore, the mechanical properties of the shafts must be known precisely and designed to provide maximum thermal resistance and to create minimum cost. Within the scope of this project, the mechanical properties of the transmission shafts used in boilers will be observed to be improved by heat treatment and determined by the tensile test. More reliable boiler design will be made by making the strength calculations of the shafts mounted on the boiler parts of these results. The prepared test samples consist of three group, samples that have not been treated with heat treatment, partial time heat treatment applied, long term heat treatment applied. Samples of 20 mm diameter were reduced to 10,12 and 14 mm diameter with lathe and 3 pieces of each diameter were prepared. Prepared samples were tested in the tensile tester in Inonu University Mechanical Engineering laboratory. In addition to these samples, cutting was done at five different angles and assembled with metal inert gas welding and tungsten inert gas welding method and subjected to tensile testing. The three different experiments performed on the samples cut in the Y-axis at 0,15,30,45 and 60 angles are as follows. Firstly, welding was done directly to the shafts that were cut, Welding has been done after applying heat treatment to the shafts and heat treatment was applied to the shafts after welding. The tensile test results of these experimental groups were observed As a result of tensile tests, tensile, yield and tensile strength and elongation of the materials were identified, the effect of heat treatment on the material was determined. As a result of these improvements, the reliability of the shafts used in boiler design has been increased. KEYWORDS: Boiler, Transmission Shaft, Tensile Test, Heat Treatment