The 25 years＇ production and application have proved that vermicular graphite iron cylinder heads with vermicularity ≥50% satisfy the machinability and performance demand of diesel engine. The method, in which using...The 25 years＇ production and application have proved that vermicular graphite iron cylinder heads with vermicularity ≥50% satisfy the machinability and performance demand of diesel engine. The method, in which using cupola-induction furnace duplex melting and pour-over process with rare earth-ferrosilicon or rare earthsilicon compound as vermJcularizing alloy plus rare earth-magnesium-ferrosilicon as stirring alloy, is an optimal vermicularizing process for obtaining satisfied vermicularity. Using top kiss risers, enlarging kissing areas and expanding covering width and making ingates to freeze earlier are the effective measures to eliminate shrinkage, blowhole and oxide inclusions in the vermicular graphite iron cylinder heads.展开更多
Magnetic drive pump has gotten great achievement and has been widely used in some special fields. Currently, the researches on magnetic drive pump have focused on hydraulic design, bearing, axial force in China, and a...Magnetic drive pump has gotten great achievement and has been widely used in some special fields. Currently, the researches on magnetic drive pump have focused on hydraulic design, bearing, axial force in China, and a new magnetic drive pump with low flow and high head have been developed overseas. However, low efficiency and large size are the common disadvantages for the magnetic drive pump. In order to study the performance of high-speed magnetic drive pump, FLUENT was used to simulate the inner flow field of magnetic drive pumps with different rotate speeds, and get velocity and pressure distributions of inner flow field. According to analysis the changes of velocity and pressure to ensure the stable operation of pump and avoid cavitation. Based on the analysis of velocity and pressure, this paper presents the pump efficiency of magnetic drive pumps with different rotated speeds by calculating the power loss in impeller and volute, hydraulic loss, volumetric loss, mechanical loss and discussing the different reasons of power loss between the magnetic drive pumps with different rotated speeds. In addition, the magnetic drive pumps were tested in a closed testing system. Pressure sensors were set in inlet and outlet of magnetic drive pumps to get the pressure and the head, while the pump efficiency could be got by calculating the power loss between the input power and the outlet power. The results of simulation and test were similar, which shows that the method of simulation is feasible. The proposed research provides the instruction to design high-speed magnetic drive pump.展开更多
The volumetric changes of castings and dimension changes of mould cavity occurring during liquid cooling and solidification of nodular iron castings were described. The feasibility and prerequisites to realize feeder-...The volumetric changes of castings and dimension changes of mould cavity occurring during liquid cooling and solidification of nodular iron castings were described. The feasibility and prerequisites to realize feeder-less production of nodular iron castings was analyzed and proved with practical examples. It was pointed out that the feeder-less foundry method is by no means a feeding-less method, and it was emphasized that adopting high carbon equivalent, high rigidity mould, simultaneous and synchronous solidification, and intensifying cooling capacity of the mould to increase feeding effect of the gating system are important to successfully realize feeder-less production of nodular iron castings.展开更多
文摘The 25 years＇ production and application have proved that vermicular graphite iron cylinder heads with vermicularity ≥50% satisfy the machinability and performance demand of diesel engine. The method, in which using cupola-induction furnace duplex melting and pour-over process with rare earth-ferrosilicon or rare earthsilicon compound as vermJcularizing alloy plus rare earth-magnesium-ferrosilicon as stirring alloy, is an optimal vermicularizing process for obtaining satisfied vermicularity. Using top kiss risers, enlarging kissing areas and expanding covering width and making ingates to freeze earlier are the effective measures to eliminate shrinkage, blowhole and oxide inclusions in the vermicular graphite iron cylinder heads.
基金supported by National Science and Technology Support Scheme of China (Grant No. 2008BAF34B10)
文摘Magnetic drive pump has gotten great achievement and has been widely used in some special fields. Currently, the researches on magnetic drive pump have focused on hydraulic design, bearing, axial force in China, and a new magnetic drive pump with low flow and high head have been developed overseas. However, low efficiency and large size are the common disadvantages for the magnetic drive pump. In order to study the performance of high-speed magnetic drive pump, FLUENT was used to simulate the inner flow field of magnetic drive pumps with different rotate speeds, and get velocity and pressure distributions of inner flow field. According to analysis the changes of velocity and pressure to ensure the stable operation of pump and avoid cavitation. Based on the analysis of velocity and pressure, this paper presents the pump efficiency of magnetic drive pumps with different rotated speeds by calculating the power loss in impeller and volute, hydraulic loss, volumetric loss, mechanical loss and discussing the different reasons of power loss between the magnetic drive pumps with different rotated speeds. In addition, the magnetic drive pumps were tested in a closed testing system. Pressure sensors were set in inlet and outlet of magnetic drive pumps to get the pressure and the head, while the pump efficiency could be got by calculating the power loss between the input power and the outlet power. The results of simulation and test were similar, which shows that the method of simulation is feasible. The proposed research provides the instruction to design high-speed magnetic drive pump.
文摘The volumetric changes of castings and dimension changes of mould cavity occurring during liquid cooling and solidification of nodular iron castings were described. The feasibility and prerequisites to realize feeder-less production of nodular iron castings was analyzed and proved with practical examples. It was pointed out that the feeder-less foundry method is by no means a feeding-less method, and it was emphasized that adopting high carbon equivalent, high rigidity mould, simultaneous and synchronous solidification, and intensifying cooling capacity of the mould to increase feeding effect of the gating system are important to successfully realize feeder-less production of nodular iron castings.
