Hitachi Metals, Ltd.

Nissan Motor Company Limited

Kimio Kubo

Koichi Akiyama

Masahide Ike

Kunio Kawai

Kouki Ohtsuka

Akira Mikami

Hiroyuki Hagiwara

Gerald P Backer

Naotaka Deki

Takashi Mimata

Hiroshi Onuma

Katuhiro Kurose

Taichi Ikejiri

Makoto Fukuhira

Hiroshi Ohnuma

An apparatus and method for casting metal in an evacuated mold cavity. The apparatus has a preferential suction zone through which a mold can be preferentially and effectively evacuated and a suction head sealingly fitting the upper surface of the mold. To the apparatus, is further provided a pressing means for pressing, in cooperation with the suction head, the mold against the inner bottom surface of a mold support chamber. By evacuating the mold through the preferential suction zone while pressing the mold to the bottom of the mold support chamber, a mold cavity is easily filled with a molten metal in such a manner to avoid casting defects such as insufficient filling, blow hole, surface fold, under fill, etc.

Vacuum casting method and vacuum casting apparatus

The occurrence of porosity defects in solidifying metal can be predicted by a computer simulation numerically analyzing the solidification process of molten metal comprising (1) dividing a mold and a mold cavity into a plurality of elements; (2) providing each of the elements with material properties of casting metal and mold, and process variables as initial data; (3) calculating a liquid fraction of each of the elements in successive predetermined time increments to examine whether nor not each of the elements is in solid-liquid coexisting zone; (4) calculating pressure gradients between each of elements in the solid-liquid coexisting zone and neighboring elements thereof by numerically analyzing an interdendritic flow of the molten metal; (5) calculating gas pressure in the molten metal in each of elements in the solid-liquid coexisting zone; (6) comparing the gas pressure with an equilibrium pressure, and calculating a porosity amount for each of elements where the gas pressure is higher than the equilibrium pressure; and (7) repeating the calculations of the steps (3) to (6) until the solidification of the molten metal is completed. Since the above method takes the effects of interdendritic flow of molten metal into consideration, the occurrence of porosity defects can be predicted accurately and directly.

Method for numerically predicting casting defects

Vacuum casting apparatus and method using the same

The conditions of casting with a permeable mold having a cavity and a runner can be optimized by a computer simulation method of (1) dividing the mold and a cavity thereof into a plurality of elements; (2) providing mold properties, a pressure and a velocity of a melt flowing into the runner as initial data with respect to each element; (3) performing computations in a step-wise manner to determine the movement of a free surface of the melt and a rate of gas flowing through the mold until the cavity is filled with the melt; (4) calculating a total volume of voids generated in the melt; (5) examining whether or not the total volume of voids is substantially zero; and (6) if the total volume of voids is not substantially zero, repeating the computations with at least one of the initial data modified until the total volume of voids becomes substantially zero.

Method for optimizing casting conditions using permeable mold by

The apparatus for producing a cast steel article has a permeable mold having a cavity, a sprue and at least one rise/run-off portion, and a vacuum apparatus, the permeable mold being provided with a hole having an opening on a mold surface near the rise/run-off portion, the vacuum apparatus being provided with a suction pipe having an opening which is brought into contact with the hole of the permeable mold, wherein the air is sucked from the hole by the vacuum apparatus, in order to conduct the casting of the article at reduced pressure.

Method and apparatus for producing cast steel article

The designing of a cavity shape of a mold by utilizing solidification analysis is conducted by (a) preparing a two-dimensional small element model of a casting to be produced in the cavity, the casting including an article portion and a portion connected thereto for feeding a melt to the article portion; (b) determining a solid fraction distribution of the model by conducting the unsteady heat transfer calculation by a heat flux method; (c) correcting the solid fraction distribution by taking into account the heat transfer in a direction perpendicular to the two-dimensional model; (d) observing whether or not there is a closed loop of the solid fraction in the article portion; and (e) modifying the cavity shape to eliminate a closed loop of the solid fraction, if any, from the article portion.

Method of designing cavity shape of mold

The present invention relates to a heat-resistant cast steel that comprises, on a weight basis, 0.06-0.20% C, 0.01-0.10% N, 0.4-2.0% Si, 0.3-1.0% Mn, not more than 0.04% P, not more than 0.04% S, 15-22% Cr, 0.01-2.0% Nb, with the balance being Fe and incidental impurities, and further preferably that is retained at a temperature not higher than the temperature of two-phase mixed region for a certain time and then is gradually cooled, after casting; a heat-resistant cast steel that comprises, on a weight basis, 0.06-0.20% C, 0.01-0.10% N, 0.4-2.0% Si, 0.3-1.0% Mn, not more than 0.04% P, not more than 0.04% S, 15-22% Cr, 0.01-2.0% Nb, 0.2-1.0% Mo, with the balance being Fe and incidental impurities, and further preferably that is retained at a temperature not higher than the temperature of two-phase mixed region for a certain time and then is gradually cooled, after casting; a heat-resistant cast steel that comprises on a weight basis, 0.06-0.20% C, 0.01-0.10% N, 0.4-2.0% Si, 0.3-1.0% Mn, not more than 0.04% P, not more than 0.04% S, 15-22% Cr, 0.01-0.10% Ti, 0.2-1.0% Mo, 0.01-1.0% Ni, with the balance being Fe and incidental impurities, and further preferably that is retained at a temperature not higher than the temperature of two-phase mixed region for a certain time and then is gradually cooled, after casting; and a heat-resistant cast steel that comprises, on a weight basis, 0.06-0.20% C, 0.01-0.10% N, 0.4-2.0% Si, 0.3-1.0% Mn, not more than 0.04 P, not more than 0.04% S, 15-22% Cr, 0.01-0.10% Ti, 0.2-1.0% Mo, 0.01-1.0% Ni, with the balance being Fe and incidental impurities, and further preferably that is retained at a temperature not higher than the temperature of two-phase mixed region for a certain time and then is gradually cooled, after casting.

Cast-to-near-net-shape steel body of heat-resistant cast steel

The present invention relates to a heat-resistant cast steel that comprises, on a weight basis, 0.06-0.20% C, 0.01-0.10% N, 0.4-2.0% Si, 0.3-1.0% Mn, not more that 0.04% P, not more than 0.04% S, 15-22% Cr, 0.01-2.0% Nb, with the balance being Fe and incidental impuriites, and further preferably that is retained at a temperature not higher than the temperature of two-phase mixed region for a cerain time and then is gradually cooled, after casting; A heat-resistant cast steel that comprises, on a weight basis, 0.06-0.20% C, 0.01-0.10% N, 0.4-2.0% Si, 0.3-1.0% Mn, not more than 0.04% P, not more than 0.04% S, 15-22% Cr, 0.01-2.0% Nb, 0.2-1.0% Mo, with the balance being Fe and incidental impurities, and further preferably that is retained at a temperature not higher than the temperature of two-phase mixed region for a certain time and then is gradually cooled, after casting; A heat-resistant cast steel that comprises, on a weight basis, 0.06-0.20% C, 0.01-0.10% N, 0.4-2.0% Si, 0.3-1.0% Mn, not more than 0.04% P, not more than 0.04% S, 15-22% Cr, 0.01-0.10% Ti, 0.2-1.0% Mo, 0.01-1.0% Ni, with the balance being Fe and incidental impurities, and further preferably that is retained at a temperature not higher than the temperature of two-phase mixed region for a certain time and then is gradually cooled, after casting; and A heat-resistant cast steel that comprises, on a weight basis, 0.06-0.20% C, 0.01-0.10% N, 0.4-2.0% Si, 0.3-1.0% Mn, not more than 0.04 P, not more than 0.04% S, 15-22%, Cr, 0.01-2.0% Nb, 0.01-0.10% Ti, 0.2-1.0% Mo, 0.01-1.0% Ni, with the balance being Fe and incidental impurities, and further preferably that is retained at a temperature not higher than the temperature of two-phase mixed region for a certain time and then is gradually cooled, after casting.

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Tochigi, Japan

Kimio Kubo