Study On Mold Filling And Deffect Of Casting Of Titanium Alloys Under Centrifugal Force Field

Titanium alloys have excellent mechanical properties but they are difficult to be machined. Investment casts in Titanium alloys with thin wall produced under the centrifugal force field have unique advantages. It has important theory significance and the practical value to the development of Titanium alloys, the optimization of craft; reduce of experimental expense with clarification of the filling rule and the formation mechanism of defect in Titanium alloys under the centrifugal force field.As the result, the filling rule and the formation mechanism of defect in Titanium alloys under the centrifugal force field have been studied by the way of similar simulation and computer numerical simulation.In this dissertation, the similar criterion of filling process of Titanium alloys under the centrifugal force field is obtained applying to the similarity theory. The filling activity of alloys at different gating systems and different rotational speeds is simulated by water under centrifugal force field. The results show that fluid fills along the back of cross gate during forward filling. Exchange between the kinetic energy and the potential energy is taken place with crashing of fluid to wall, at the same time the primary pressure head become to the second pressure head. Then fluid stream go on filling along other running channels and stuff the cavity layer by layer. Free surface of liquid during filling backward process is on the circular arc with center is rotation axis. So there is not tangential motion, but only radial motion. Fluid fills backward directly for the gating system without ingate , and the final stuffing place is the gateway.The change rule of the filling speed and the filling length has been studied under the centrifugal force field. Results show that, the filling speed reduces along with the time increasing, and the decrease is more rapid at the initial stage. And then, the decrease keeps smooth. For the same gating system, the filling speed reduces with the enhancing of the rotation speed in the same time. During the filling process, filling length increases with the increase of the filling time, and the change is obvious at the initial period. Then the change becomes smooth. The influence of the filling speed on the filling length can be ignored at the...