| Summary: In this study, billet to billet welding defect which occurs in direct extrusion during the production of the complex multi holes closed aluminum profiles that are subjected to static and dynamics loading conditions as in railway systems was studied. To this goal, the die porthole geometry and port section area relation between the areas fed by the die port in profile section were considered as main parameters. It is crucially important for structural profile industry to determine how long the billet to billet welding scrap continues and minimizing the scrap length.
In the first phase of this this study, a numerical study was conducted to determine the influence of the die porthole geometry on the transverse welding length by means of four different die designs with simple square hollow profiles. In the second phase of this study, the above obtained data was evaluated and extrusion trials in industrial conditions were carried to determine the exact transverse welding length. Obtained results were compared both with each other and with the experimental results of the previous studies. Consequently, it was noted that small section area of symmetrical die ports which has smaller port volume has shortened the transverse welding length. Ratio between die port area and profile part section area fed by the die port is more effective than the small die port size in the dies which have unsymmetrical die ports. It is concluded that if this ratio for all die ports is close to each other the billet to billet transverse weld length decreases.
Key Words: Aluminium extrusion, Structural profile, Transverse weld, Charge weld, Extrusion simulation, Transverse weld length calculation, Extrusion welding. |
