巻号一覧
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50 巻, 11 号
選択された号の論文の6件中1～6を表示しています
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研究論文
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小松 康彦, 杉本 繁利, 北川 久善1978 年 50 巻 11 号 p. 653-658
発行日: 1978/11/25
公開日: 2012/06/02
ジャーナル フリーIt is known that special ceramics containing alumina cement can be enveloped soundly with molten metal and kept under shrink-fit condition. In this report, the internal stress of ceramics-enveloped casting which is a very important factor in terms of durability was investigated by X-ray and strain gauge methods. The stress on the metal surface of cylindrical test specimen which enveloped ceramics with spheroidal graphite cast iron had a tension of 1.33kg/mm2. The contact pressure on the boundary between metal and ceramics, which is the shrink-fit force was calculated to be 0.23kg/mm2 and the stress on the ceramics surface be a compression of 1.28kg/mm2. It was also made clear that the shrink-fit force is affected by the casting condition and increases 3 times by strengthening the restriction of the mold and increases 1.7 times by coating the outside surface of the ceramics.抄録全体を表示PDF形式でダウンロード (751K) -
房村 信雄, 名古屋 俊士, 雄谷 重夫, 高田 孝保, 藤井 孝彦1978 年 50 巻 11 号 p. 659-664
発行日: 1978/11/25
公開日: 2012/06/02
ジャーナル フリーThe quantity of copper fume increases in proportion to the content of zinc, lead, and tin in the molten copper alloy. The induction factor γ for copper fume generation of alloying elements is in the order of γZn>γPb>γSn, and among them γZn is the highest. The restraint factor δ against zinc fume generation of alloying elements is in the order of δCu>δSn>δPb, according to the vapor pressure of each element. The effect of induction is stronger than that of restraint in the metallic fume generation in copper alloy.抄録全体を表示PDF形式でダウンロード (670K) -
坂本 敏正, ��川 克之, ��田 千里, 中村 実人, 森 隆資, 高田 寿1978 年 50 巻 11 号 p. 665-670
発行日: 1978/11/25
公開日: 2012/06/02
ジャーナル フリーThe relation between eutectic cell number Ne (number/cm2) and cooling rate (°C/hr) or solidification rate V (cm/hr) is represented by the following equation. Ne = A·Rm, Ne = B·Vn, where A, B, m and n are constants. The relation between graphite spacing in eutectic cell λe(μm) and R or V is represented by the following equation. λe = C·Rk, λe = D·Vl, where C, D, k and l are constants (k, l<0). But the relation of λe−R or λe−V was not the extension of λp−R or λp−V relation in the lamellar structure, where λp is graphite spacing in lamellar structure. Whenever eutectic cells were observed, there were austenitic dendrites in the specimen. Eutectic cells formed in line around the axis of austenitic dendrite. Graphite in a eutectic cell was three-dimensionally continuous. Graphite was intermeshed at the colony boundary but graphite was free at the eutectic cell boundary. There was a sub-boundary, which was characteristic of a colony boundary in the eutectic cell. It was assumed from the calculation of wettability that austenitic dendrite could not be the nucleation site of graphite, while graphite could be the site for austenite. Undercooled graphite which generated in a colony or in a eutectic cell, was considered to be a cooperative growth.抄録全体を表示PDF形式でダウンロード (805K) -
磯部 俊夫, 久保田 昌男, 北岡 山治1978 年 50 巻 11 号 p. 671-676
発行日: 1978/11/25
公開日: 2012/06/02
ジャーナル フリーFreezing conditions for preventing cast cracks in aluminum alloy castings were investigated in terms of the tensile strength of the alloy in the solid-liquid temperature range and contraction stress which was estimated by the calculation on a simple freezing model. Whether the material is susceptible to cast cracks or not is determined by comparing ‘cast cracking parameter’ with ‘critical cast cracking parameter’. The former is expressed as a ratio of temperature decrease at the region of final stage of freezing to that at the region of initial stage of freezing. This parameter is empirically determined by the casting conditions. The latter is mainly determined by the physical and mechanical properties of the alloy such as semi-solidus temperature range, strength increase and elongation in this zone, coefficient of linear shrinkage and Young’s modulus.抄録全体を表示PDF形式でダウンロード (710K) -
山本 善章, 岩堀 弘昭, 米倉 浩司, 中村 元志1978 年 50 巻 11 号 p. 677-682
発行日: 1978/11/25
公開日: 2012/06/02
ジャーナル フリーGas defects such as blowholes and pinholes are often observed in iron castings cast in core molds made by the CO2 process. This study was undertaken to investigate the behavior of gas pressure within various types of CO2 mold cores. Gas pressure at various core portions during casting at 1,400°C were measured with a semiconductor pressure gauge developed in our laboratory. The cores used, which were 75mm in width, 150mm in length and 20mm in thickness had a core print on the open side for degassing. The factors in mold making such as sodium silicate content in the mold core, standing time in air and drying temperature after CO2 gassing were varied.
The gas pressure-time curve in shell mold cores provided three peaks (peak; I, II, III), but the curve in CO2 mold cores provided only two peaks (peak; I, II). Peak II in the latter was much higher than that in the former. The difference in the peak height between the two types of cores may be attributed to vaporization of water, which easily vaporizes and is amply contained in the water glass. The CO2-passed core contained more water after being kept in a high humid environment than that after being kept in 60% humidity at 24°C. When molten iron was cast in the water-rich mold, the gas pressure exceeded the hydrostatic pressure of the molten metal, resulting in gas blowing which further caused gas defects in the casting. If the CO2 mold was kept in low humid condition for a sufficient period or dried at a temperature above 100°C, the water content in the mold decreased and led to the decrease of gas pressure generating in the mold core, thus preventing casting defects due to gas bubbling.抄録全体を表示PDF形式でダウンロード (670K) -
相沢 達志1978 年 50 巻 11 号 p. 683-687
発行日: 1978/11/25
公開日: 2012/06/02
ジャーナル フリーWhen a molten metal is solidified at an undercooled temperature below the equilibrium liquidus, the nucleation rate dN/dt and the growth rate dR/dt are given by dN/dt=A·θ·dθ and dR/dt=B·θ2 where A and B are constants. On the assumption that the above theory can be applied to all sections of the casting, the author compiled a digital computer program in using a differential method for simulating the solidification of the casting. Furthermore, using this program, the influence of the nucleation rate and the growth rate on the width of mushy zone was studied. The results indicated that the width of mushy zone increased when the nucleation rate was higher, or when the growth rate was lower. It was considered from these results that the width of mushy zone in spheroidal graphite cast iron is longer than gray cast iron by reason of its slow growth rate, and the width of mushy zone in inoculated cast iron is longer than that in uninoculated cast iron because the nucleation rate is higher.抄録全体を表示PDF形式でダウンロード (623K)
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