In addition to mold rigidity and metallurgical quality of iron melting, the main reasons causing riser feeding failure in nodular iron castings production are: (a) open and cold metal flowing-over risers were adopted;...In addition to mold rigidity and metallurgical quality of iron melting, the main reasons causing riser feeding failure in nodular iron castings production are: (a) open and cold metal flowing-over risers were adopted; (b) riser location was not proper; (c) riser was too small or/and not enough high; (d) ingates did not freeze up instantly as soon as pouring finished; (e) there’re isolated hot spots in the casting which are not connected with feeding channel of the riser; (f) the feeding channel of castings with small size and thin sections is too narrow for feeding liquid to enter casting; and so on.展开更多
For settling the question of feeding speed in applying the cored-wire method to spheroidize ductile iron melt, ANSYS software was applied to simulate the heat transfer and mass transfer, and the melt time of the steel...For settling the question of feeding speed in applying the cored-wire method to spheroidize ductile iron melt, ANSYS software was applied to simulate the heat transfer and mass transfer, and the melt time of the steel strip in the iron melt was determined by linking the heat transfer and mass transfer, and then the feeding speed was calcufated. Conclusions have been drawn that the iron layer was formed on the surface of the cored-wire during the wire-feeding process. The thickness is 0.073 mm when the temperature of the iron melt is 1500℃, the time from formation to remelting of the iron layer is 0.063 s. When the temperature of the iron melt is below 1500℃, the time taken for the steel strip to melt is rapidly shortened. When the temperature of the iron melt is above 1500℃, the variation amplitude of the steel strip melt change with time is gradually diminished. The melt time of the steel strip is rapidly increased with the increase of the steel strip thickness. When the temperature of the iron melt is 1500℃ and the carbon content is 4%, the melt time of a steel strip, which has a thickness of 0.5 mm, is thrice that of a steel strip whose thickness is 0.3 mm. The calculation results of the feeding speed are basically in agreement with the applied feeding speed in the factory.展开更多
Children on exclusive jejunal feeding may be at risk of iron deficiency due to the feeds bypassing the duodenum,which is the primary site for iron absorption.We describe the biochemical and hematological features of s...Children on exclusive jejunal feeding may be at risk of iron deficiency due to the feeds bypassing the duodenum,which is the primary site for iron absorption.We describe the biochemical and hematological features of six children on exclusive jejunal feeding who did not receive iron supplementation.At a mean(standard deviation)period of 11(6.5)mo after commencing jejunal feeds,there was a significant reduction in both serum iron(18.5 g/L vs 9.8 g/L,P=0.01)and transferrin saturation levels(23.1%vs 13.7%,P=0.02),suggesting iron deficiency.However,there was no significant change in ferritin,hemoglobin and mean corpuscular volume levels post-commencement of jejunal feeds.This may be the result of small bowel adaptation in response to early iron deficiency.Larger and longer term prospective studies are required to investigate if children on jejunal feeds are at risk of developing iron deficiency.展开更多
文摘In addition to mold rigidity and metallurgical quality of iron melting, the main reasons causing riser feeding failure in nodular iron castings production are: (a) open and cold metal flowing-over risers were adopted; (b) riser location was not proper; (c) riser was too small or/and not enough high; (d) ingates did not freeze up instantly as soon as pouring finished; (e) there’re isolated hot spots in the casting which are not connected with feeding channel of the riser; (f) the feeding channel of castings with small size and thin sections is too narrow for feeding liquid to enter casting; and so on.
文摘For settling the question of feeding speed in applying the cored-wire method to spheroidize ductile iron melt, ANSYS software was applied to simulate the heat transfer and mass transfer, and the melt time of the steel strip in the iron melt was determined by linking the heat transfer and mass transfer, and then the feeding speed was calcufated. Conclusions have been drawn that the iron layer was formed on the surface of the cored-wire during the wire-feeding process. The thickness is 0.073 mm when the temperature of the iron melt is 1500℃, the time from formation to remelting of the iron layer is 0.063 s. When the temperature of the iron melt is below 1500℃, the time taken for the steel strip to melt is rapidly shortened. When the temperature of the iron melt is above 1500℃, the variation amplitude of the steel strip melt change with time is gradually diminished. The melt time of the steel strip is rapidly increased with the increase of the steel strip thickness. When the temperature of the iron melt is 1500℃ and the carbon content is 4%, the melt time of a steel strip, which has a thickness of 0.5 mm, is thrice that of a steel strip whose thickness is 0.3 mm. The calculation results of the feeding speed are basically in agreement with the applied feeding speed in the factory.
文摘Children on exclusive jejunal feeding may be at risk of iron deficiency due to the feeds bypassing the duodenum,which is the primary site for iron absorption.We describe the biochemical and hematological features of six children on exclusive jejunal feeding who did not receive iron supplementation.At a mean(standard deviation)period of 11(6.5)mo after commencing jejunal feeds,there was a significant reduction in both serum iron(18.5 g/L vs 9.8 g/L,P=0.01)and transferrin saturation levels(23.1%vs 13.7%,P=0.02),suggesting iron deficiency.However,there was no significant change in ferritin,hemoglobin and mean corpuscular volume levels post-commencement of jejunal feeds.This may be the result of small bowel adaptation in response to early iron deficiency.Larger and longer term prospective studies are required to investigate if children on jejunal feeds are at risk of developing iron deficiency.
