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56 巻, 11 号
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研究論文
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野村 宏之, 渡辺 学, 坂野 武男1984 年 56 巻 11 号 p. 651-657
発行日: 1984/11/25
公開日: 2011/11/26
ジャーナル フリーA basic study of a cooling process was conducted to establish the optimum control system for hot sand cooling in the foundry. The present work is especially directed towards clarifying the mechanism of cooling of dry state sand in both the batch-type and the one-pass fluidized bed. The mathematical model includes linear differential equations for phase-to-phase heat transfer. Computer simulations on both transient and steady state temperature of the bed are provided. Temperature changes have been experimentally measured under various conditions of air flow rate, sand feed rate and inlet sand temperature. Good agreement between the experiments and the simulations has been found. In order to test the stability of the cooling system, sensitivity analysis of the model has been performed. A special attention was paid to the variation of steady state bed temperature owing to the change of inlet sand temperature. The results of computer simulations are presented and compared with the experiments. The proposed model has been shown to explain the mechanism of the cooling process.抄録全体を表示PDF形式でダウンロード (744K) -
前園 敏郎, 大塚 芳臣, 高橋 良治, 大塚 公輝1984 年 56 巻 11 号 p. 658-663
発行日: 1984/11/25
公開日: 2011/11/26
ジャーナル フリーFatigue fracture is known to proceed by initiation and propagation of cracks. The both may be considered to depend upon matrix and graphite structures. On this assumption two kinds of spheroidal graphite cast iron and two kinds of compacted/vermicular graphite cast iron were prepared. Unnotched specimens and notched specimens with a 1.2mm through hole were machined from them and tested on the Ono-type rotary bending fatigue tester. The experimental results are summarized as follows : (1) Fatigue cracks propagate more slowly in the compacted/vermicular graphite cast iron than in the spheroidal graphite cast iron. The causes may be attributed to the difference in graphite shape. (2) As long as crack length l is shorter than about 5mm, the propagation velocity of a fatigue crack is nearly proportional to l, irrespective of material. (3) Fatigue cracks propagate faster in GGV30 (tentative German standard) than in GGV40 due to the difference in the resistance of the martrix structure against crack propagation. The same tendency was observed also in spheroidal graphite cast iron.抄録全体を表示PDF形式でダウンロード (602K) -
宮沢 信夫, 花崎 紘一1984 年 56 巻 11 号 p. 664-670
発行日: 1984/11/25
公開日: 2011/11/26
ジャーナル フリーA previous study by the authors revealed that dry sand molds bonded with enzyme-converted malt dextrine, starch phosphate or starch treated with urea-phosphoric acid indicated superior dry compressive strength, and that various characteristics of the dry sand mold at normal temperature such as compressive strength depended on the quantity of water used for pasting starch. In the present study, therefore, the optimum quantity of water for pasting starch was investigated. Since binders are required to give the mold hot strength, high temperature characteristics of the mold binders with those starches were examined. The results indicated that satisfactory heat resistance could not be obtained by the individual starch alone, but a heat resistant starch specially modified for the purpose of heat resistance showed excellent hot strength.抄録全体を表示PDF形式でダウンロード (708K) -
近藤 康雄, 福迫 達一1984 年 56 巻 11 号 p. 671-676
発行日: 1984/11/25
公開日: 2011/11/26
ジャーナル フリーUsing a water model, the flow phenomena in a gating system under strong turbulence at the beginning of a pouring operation were studied. Bubbles mixed in water during pouring operation often adhere to the inside wall of ingates at the junction of runner and ingates, and this phenomenon was particularly notable in the early stage of pouring operation. Moreover, in the case of a gating system without a runner extension, as compared with a gating system with a runner extension, bubbles adhered to the inside wall of ingates more frequently and the scatter of water distribution ratio was larger. When water contains a large quantity of bubbles, the flow rate through the ingates is less than the pure water flow, and if bubbles run into the mold cavity, forced convection in the cavity is violently disturbed.抄録全体を表示PDF形式でダウンロード (686K) -
吉成 明, 新山 英輔, 森本 庄吾, 森川 穣1984 年 56 巻 11 号 p. 677-682
発行日: 1984/11/25
公開日: 2011/11/26
ジャーナル フリーThe heat flow in mold-withdrawal type unidirectional solidification was analyzed by using a steady state model. The results agreed qualitatively with experimental values of Ni-base superalloys. Under ordinary casting conditions the temperature gradient is controlled principally by heating conditions. Temperature gradient increases in proportion to the furnace temperature and also to the square-root of the apparent heat transfer coefficient. On the other hand, it is inversely proportional to the square-root of the casting radius. In order to maintain high temperature gradient, the level of the solidification interface must be maintained inside the heating furnace. At a location where casting section is enlarged upwards, the position of solidification interface tends to deviate downwards. As the interface moves outside the furnace, the temperature gradient decreases abruptly. This can be avoided by temporarily decreasing the withdrawal rate.抄録全体を表示PDF形式でダウンロード (635K) -
野口 徹, 宮城 一裕, 成田 利勝, 長岡 金吾1984 年 56 巻 11 号 p. 683-689
発行日: 1984/11/25
公開日: 2011/11/26
ジャーナル フリーIn spheroidal graphite cast iron the size distribution of graphite nodules affects the mechanical, thermal and other properties of the material. The mean nodule diameter, the average nodule number per unit area, and other parameters are used to express a quantitative description of the distribution. However, these factors obtained by planar observation of a section show only the two-dimensional distribution of graphite nodules which are actually distributed three-dimensionally in the matrix. A method is suggested in this paper to convert the two-dimensional distribution to a three-dimensional distribution based on Saltykov's theory, and is applied to some specimens with various sizes of graphite nodules.
Calculations of three-dimensional size distributions showed that the relative number of small nodules was larger than that in the observed two-dimensional distribution. The effect of large nodules in the volume distribution was stronger than in the area distribution. The mean diameters calculated three-dimensionally from the volume fraction and two-dimensionally from the area fraction were identical. There was a good linear relation between the median diameters in volume and area distributions, the former being about 10% larger than the latter, Average nodule number per unit volume and area, and average distance between nodules in volume and area also correlated well. Accordingly, parameters from two-dimensional observation are acceptable in making a qualitative study of graphite nodule distributions. It must be noted, however, that nodules of a large diameter with very small frequency affect the volume fraction and may influence some properties of the material.抄録全体を表示PDF形式でダウンロード (658K)
技術報告
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小野 修二, 角田 英雄1984 年 56 巻 11 号 p. 690-696
発行日: 1984/11/25
公開日: 2015/01/27
ジャーナル フリーPDF形式でダウンロード (3199K)
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