The productivity of China’s nonferrous metals industry during 1980-1990 has been analysed. The important factors which constrain the productivity of the nonferrous metals industry have been studied, the methods of im...The productivity of China’s nonferrous metals industry during 1980-1990 has been analysed. The important factors which constrain the productivity of the nonferrous metals industry have been studied, the methods of improving the productivity of the nonferrous metals industry have been discussed.展开更多
This paper presents a modeling and control of molten metal＇s pressure in pressing process using an innovative iron casting developed by our group. In this method, molten metal is directly poured into a lower mold, an...This paper presents a modeling and control of molten metal＇s pressure in pressing process using an innovative iron casting developed by our group. In this method, molten metal is directly poured into a lower mold, and then pressed to fill cavity by an upper mold being lowered down. For complex liquid flow during pressing, the liquid＇s pressure changing inside vertical path with various contraction and expansion geometries is newly modeled via the unstationary Bernoulli equation. The mathematical model is derived for a control design of pressing. To conduct the pressing velocity design algorithm, an unknown parameter of proposed model considering viscous flow is identified by using CFD （Computational Fluid Dynamics） with heat flow calculation. Control performance using a multi-switching velocity pattern is confirmed as an effective control design using the pressure model, because the pressure fluctuation has discontinuous variation points. Substituting detailed information for mold shape, poured volume and initial temperature into a developed control input generator, an optimum pressing velocity design and a robust design for defect-free production are proposed by the design algorithm based on the construction of an inverse system comprised of the sequential switching from higher to lower speed. Consequently, the effectiveness of the pressing control with reasonable pressure suppression has been demonstrated through CFD.展开更多
基金The project was financially supported by the Chima National Natural Science Foundation
文摘The productivity of China’s nonferrous metals industry during 1980-1990 has been analysed. The important factors which constrain the productivity of the nonferrous metals industry have been studied, the methods of improving the productivity of the nonferrous metals industry have been discussed.
文摘This paper presents a modeling and control of molten metal＇s pressure in pressing process using an innovative iron casting developed by our group. In this method, molten metal is directly poured into a lower mold, and then pressed to fill cavity by an upper mold being lowered down. For complex liquid flow during pressing, the liquid＇s pressure changing inside vertical path with various contraction and expansion geometries is newly modeled via the unstationary Bernoulli equation. The mathematical model is derived for a control design of pressing. To conduct the pressing velocity design algorithm, an unknown parameter of proposed model considering viscous flow is identified by using CFD （Computational Fluid Dynamics） with heat flow calculation. Control performance using a multi-switching velocity pattern is confirmed as an effective control design using the pressure model, because the pressure fluctuation has discontinuous variation points. Substituting detailed information for mold shape, poured volume and initial temperature into a developed control input generator, an optimum pressing velocity design and a robust design for defect-free production are proposed by the design algorithm based on the construction of an inverse system comprised of the sequential switching from higher to lower speed. Consequently, the effectiveness of the pressing control with reasonable pressure suppression has been demonstrated through CFD.
