Abstract: A method for predicting and preventing occurrence of shrinkage cavity in an iron casting of any of various shapes or in each part of an iron casting precisely prior to casting. The shape of an iron casting is approximated entirely or partially to a rectangular parallelepiped or a cube, to the sum of the two long sides is divided by the short side to determine a shape coefficient, and occurrence of shrinkage cavity is predicted by determining whether the value exceeds a predetermined value (determination coefficient) or not.

Abstract: 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.

Abstract: 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 equilibr

Abstract: A vacuum casting apparatus of the invention in which a melt is introduced into a mold cavity under vacuum, comprises (a) a vacuum vessel having at least one opening at its bottom; (b) a mold disposed within the vacuum vessel and having a mold cavity, a runner having an opening at a position under the opening of the vacuum vessel and extending along at least partially the side of the mold cavity, the mold cavity communicating with the runner through a plurality of filling passages, and a suction recess formed near a riser; and (c) a vacuum means communicating with the vacuum vessel. When the vacuum means evacuates the interior of the vacuum vessel, the mold cavity is rapidly evacuated to result in rapid filling of the cavity with a melt.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A blood pressure measurement system comprises a determination means for determining whether a cuff pressure is increasing for preparation purposes or decreasing for measurement purposes. The determination means includes a comparator for comparing the current cuff pressure with the last cuff pressure, and detection means for detecting whether a difference between the current cuff pressure and the last cuff pressure is smaller than a predetermined value. Another determination means is provided for detecting whether the cuff pressure is first increased to a desired level higher than systolic pressure of a person to be measured. A reset means is provided for automatically resetting the system when the cuff pressure is decreased to a predetermined level after completion of measurement.

Abstract: A sphygmomanometer includes a blood pressure detector, a compensation circuit for providing polygonal line approximation functions suitable for piezo-electric characteristics of the blood pressure detector according to compensation data externally applied thereto, and a pressure determination circuit for determining pressure values using the polygonal line approximation functions from the values measured by the blood pressure detector for a predetermined time period.