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
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
The Proportional Solidification Technology believes that advancing the expansion of graphite precipitation is favorable for fully utilizing the expansion to offset the contraction and minimizing feeder size.But this a...The Proportional Solidification Technology believes that advancing the expansion of graphite precipitation is favorable for fully utilizing the expansion to offset the contraction and minimizing feeder size.But this author has proved that advancing the expansion is unfavorable for both feeding from the feeder and the self-feeding by expansion.On contrary,advancing the contraction is favorable for both kinds of feeding and favorable for avoiding shrinkage.The feeding efficiency of feeders cannot be increased by advancing the expansion of the casting,but can only be increased by accelerating cooling and contraction of the casting,and(or)by delaying the freezing of the feeders.In order to fully utilize the expansion to offset the contraction,it is a must to ensure that all inlets and outlets of a casting being poured are blocked rapidly at the moment when pouring is finished.It is pointed out that blocking at the earlier frozen feeder neck is unfavorable for both feeding from the feeder and the self-feeding by expansion;whereas blocking at earlier frozen ingates is favorable for both kinds of feeding.展开更多
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)...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
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.
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.
文摘The Proportional Solidification Technology believes that advancing the expansion of graphite precipitation is favorable for fully utilizing the expansion to offset the contraction and minimizing feeder size.But this author has proved that advancing the expansion is unfavorable for both feeding from the feeder and the self-feeding by expansion.On contrary,advancing the contraction is favorable for both kinds of feeding and favorable for avoiding shrinkage.The feeding efficiency of feeders cannot be increased by advancing the expansion of the casting,but can only be increased by accelerating cooling and contraction of the casting,and(or)by delaying the freezing of the feeders.In order to fully utilize the expansion to offset the contraction,it is a must to ensure that all inlets and outlets of a casting being poured are blocked rapidly at the moment when pouring is finished.It is pointed out that blocking at the earlier frozen feeder neck is unfavorable for both feeding from the feeder and the self-feeding by expansion;whereas blocking at earlier frozen ingates is favorable for both kinds of feeding.
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.
