Effects of centrifugal and Coriolis forces on the mold-filling behavior of titanium melts in vertically rotating molds

The vertical centrifugal-casting technique is widely used in the manufacture of various irregularly-shaped castings of advanced structural alloys with thin walls,complex shapes and/or large sizes.These castings are used in the increasing applications in aero-space/aviation industries,human teeth/bone repairs with near-net shaped components,etc.In a vertically rotating casting system,the mold-filling processes of alloy melts,coupled with solidification-heat transfer,may be much more complicated,because they are driven simultaneously by gravity,centrifugal and Coriolis forces.In the present work,an N-S/VOF-equations-based model,solved using a SOLA-VOF algorithm,under a rotating coordinate system was applied to numerically investigate the impacts of centrifugal and Coriolis forces on metallic melt mold-filling processes in different vertical centrifugal-casting configurations with different mold-rotation rates using an authors'computer-codes system.The computational results show that the Coriolis force may cause remarkable variations in the flow patterns in the casting-part-cavities of a large horizontal-section area and directly connected to the sprue via a short ingate in a vertical centrifugal-casting process.A"turn-back"mold-filling technique,which only takes advantage of the centrifugal force in a transient rotating melt system,has been confirmed to be a rational centrifugal-casting process in order to achieve smooth and layer-by-layer casting-cavities-filling control.The simulated mold-filling processes of Ti-6Al-4V alloy melt,in a vertical centrifugal-casting system with horizontally-connected plate-casting cavities,show reasonable agreement with experimental results from the literature.

The vertical centrifugal-casting technique is widely used in the manufacture of various irregularlyshaped castings of advanced structural alloys with thin walls, complex shapes and/or large sizes. These castings are used in the increasing applications in aero-space/aviation industries, human teeth/bone repairs with nearnet shaped components, etc. In a vertically rotating casting system, the mold-filling processes of alloy melts, coupled with solidification-heat transfer, may be much more complicated, because they are driven simultaneously by gravity, centrifugal and Coriolis forces. In the present work, an N-SNOF-equations-based model, solved using a SOLA-VOF algorithm, under a rotating coordinate system was applied to numerically investigate the impacts of centrifugal and Coriolis forces on metallic melt mold-filling processes in different vertical centrifugal-casting configurations with different mold-rotation rates using an authors＇ computer-codes system. The computational results show that the Coriolis force may cause remarkable variations in the flow patterns in the casting-part-cavities of a large horizontal-section area and directly connected to the sprue via a short ingate in a vertical centrifugal-casting process. A ＂turn-back＂ mold-filling technique, which only takes advantage of the centrifugal force in a transient rotating melt system, has been confirmed to be a rational centrifugal-casting process in order to achieve smooth and layer-by-layer casting-cavities-filling control. The simulated mold-filling processes of Ti-6AI-4V alloy melt, in a vertical centrifugal-casting system with horizontally-connected plate-casting cavities, show reasonable agreement with experimental results from the literature.