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Optimum injection considering shot timing for Die casting by using CFD simulator
Yoshifumi Kuriyama,Ken’ichi Yano,Seishi Nishido 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
Die casting is adequate for mass production and it has the advantage of being able to yield a complicated shape accurately. A defect of Die casting for high-speed injection molding is the occurrence of shrinkage cavities. To avoid the shrinkage cavities, velocity control of a plunger is very effective. However, the velocity control input is manually constructed by skillful workers because analysis behavior of molten metal is very difficult and the injection molding is performed in invisible places in the mold. In this paper, fluid behavior and quantity of air entrainment caused by a die casting plunger movement are analyzed by using CFD. The optimum velocity control input of die casting plunger is calculated in order to enable the reduction of air entrainment and prevent the occurrence of shrinkage cavities in die casting product. An optimization is performed by the Genetic algorithm incorporating CFD simulator.
Imayama, T.,Takeshita, T.,Yi, K.,Cho, D.L.,Kitajima, K.,Tsutsumi, Y.,Kayama, M.,Nishido, H.,Okumura, T.,Yagi, K.,Itaya, T.,Sano, Y. Universitetsforlaget ; Elsevier Science Ltd 2012 Lithos Vol.134 No.-
The timing of partial melting and the pressure-temperature (P-T) paths in the High Himalayan Crystalline Sequence (HHCS) in far-eastern Nepal has been investigated using zircon chronology, rare earth element (REE) compositions, and P-T pseudosection analysis. Zircon from migmatites formed during Himalayan thermal events displays inherited magmatic core overgrown by two generations of metamorphic rims. The new rims are distinguished on the basis of their Tertiary ages, low MREE contents, and low Th/U ratios. The inner zircon rims from Sil+Grt+Bt+Kfs+Pl+Qtz and Ky+Sil+Grt+Bt+Ms+Pl+Qtz migmatites at different structural level of the HHCS display ages of c. 33-28Ma (Early Oligocene) and c. 21-18Ma (Early Miocene): these rims are characterized by flat MREE to HREE patterns and were overgrown by partial melt through muscovite dehydration melting under the stability of garnet, which occurred at P=c. 7-10kbar and T=c. 730-780<SUP>o</SUP>C, and at P=c. 8-14kbar and T=c. 720-770<SUP>o</SUP>C, respectively. The outer zircon rims are relatively enriched in HREE with respect to the inner rims and were overgrown at c. 27-23Ma (Late Oligocene) and at c. 18-16Ma (Early Miocene) during melt crystallization accompanying breakdown of garnet at P=c. 4-7kbar and T=c. 650-725<SUP>o</SUP>C. Early Miocene Ms-Bt leucogranites with two successively overgrown zircon rims at c. 18.3+/-0.3Ma and c. 16.3+/-0.2Ma were intruded into Early Oligocene migmatite hosts. Microstructural observations and the corresponding P-T conditions associated with the two generations of zircon rims indicate that the Early Oligocene and Early Miocene migmatites show relatively isobaric and nearly isothermal P-T paths during exhumation, respectively. The inferences are consistent with higher average cooling rates for the Early Miocene (c. 30-40<SUP>o</SUP>C/My) than the Early Oligocene (c. 15-25<SUP>o</SUP>C/My) migmatites, inferred from peak-T conditions and FT (c. 6Ma for both migmatites) and U-Pb zircon ages. The P-T-t paths of the two migmatites indicate that burial of the Early Miocene migmatites has been coeval with exhumation of the Early Oligocene migmatites, implying the formation of large-scale thrust within the HHCS.