A New Mathematical Model for the Prediction of the Critical Velocity of Liquid Metals
The link between the entrAlnment of non metallic phases into the bulk liquid metal and the engineering quality of cast parts has been long recognised in casting literature. In particular ,oxide skin forming alloys(such as those of aluminium,magnesium and ductile iron) flowing through vertical bottom gates have been shown to be critically sensitive to those entrAlnment events. In this work, it is presented the development of a mathematical model for the calculation of the critical flow velocity, vcr, for that kind of geometry. As a theoretical basis for this model, the principle of conservation of the momentum of the molten metal stream was applied specifically for flat and cylindrical flow geometries. This yielded equilibrium equations for the three types of fluid dynamic forces concerned, namely mass (gravity) , surface tension and inertia, enabling the obtAlning of an expression for vcr A comparison between the calculated values of vcr and those found in numerical and experimental flow trials using metals and water alike was made, revealing a good accuracy of the model. To conclude, the casting trials of one industrial component by means of gravity pouring and the new EPGS (Electromagnetic Pump Green Sand) casting technique are briefly described. The sensibly higher quality of the cast part produced by the EPGS process is explAlned because of the unique mAlntenance of the flow velocity below the modelled critical values at all times of the filling.
entrAlnment critical velocity EPGS process
Rafael Cuesta Antonio Maroto Jorge Martin
Foundation for the Research and Development in Transport and Energy, CIDAUT, P. Tecnologico de Boecillo, Boecillo, Valladolid, Spain
国际会议
69th World Foundry Congress(第69届世界铸造会议 WFC 2010)
杭州
英文
492-497
2010-10-16(万方平台首次上网日期,不代表论文的发表时间)