Verringerung der Randzone von vertikal gegossenen Stranggussbolzen

One of the quality criteria for continuous aluminum casting is the thickness of the edge zone. This is particularly important if the continuous cast billets are subsequently used as starting material for extrusion processes. If the thickness of the edge zone is too big, either the extrusion process must be interrupted prematurely in order to avoid defects in the profile, or the edge zone must be removed by machining before extrusion. Both variants increase the proportion of recycled material and therefore the production costs. This study focuses on the EN AW-6026LF-aluminium alloy, manufactured using the open-top continuous casting process. The main aim is to reduce the edge zone of the billets without jeopardizing the process stability. In pursuit of this objective, the initial step involved documenting and assessing the casting system, followed by its conversion into a 3D model. This model facilitated simulations to analyze both the water distribution across the pouring table and the water flow within the mold. Concurrently, the melt temperature within the mold was monitored during the casting process. Subsequent to casting, samples were taken from the billets to assess the edge zone thickness and chemical composition of each billet individually. The simulations demonstrated that the water flow in the casting table could be effectively controlled very without significant effort by incorporating baffle plates. It turned out that there are installations in the table that lead to this uneven flow into the molds and thus to the high edge zone thickness. This situation can be improved by modifying the design of the molds by inserting a nozzle or T-plate and by shortening the active primary cooling zone. However, this harbors the risk of the strand rupturing and causing deflagrations.