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40 巻, 12 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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鈴木 和郎, 山岡 弘, 小田 光雄1968 年 40 巻 12 号 p. 927-941
発行日: 1968/12/25
公開日: 2012/10/04
ジャーナル フリーIn casting molten steel into sand mold it was observed that the formation of scabs was closely related to the speed of thermal expansion of sand mold surrounded with molten steel. That is, the formation of scabs was promoted by increasing the maximum rate of thermal expansion or shortening the time needed for the rate of thermal expansion to attain its maximum. during pouring molten steel. As a result of experiment, the analysis of scab defects could be quantitatively performed. To eliminate expansion scabs it needed to reduce the rate of thermal expansion of sand mold as low possible. Addition of various thermal plastic material of 0.2 to 1.0% to molding sand was effective upon reducing scab defects to an extent of one third.抄録全体を表示PDF形式でダウンロード (1511K) -
喜野 甚哉, 松森 勇1968 年 40 巻 12 号 p. 941-949
発行日: 1968/12/25
公開日: 2012/10/04
ジャーナル フリーMetal penetration is caused due to the penetration of molten metal into gaps of sand grains. In experinents metal pemetration was studied on heavy steel castings. Experimental results were as follows :
1) Metal penetration was probably caused due to the penetration of molten steel into the gaps of sand grains.
2) In case molding sand consisted of silica sand and chromite sand, there occurred fusion as well as metal penetration. In contrast to this, metal penetration took place without the of fusion, in case molding sand consited of nothing but zircon.
3) Neither zircon sand nor chromite sand did always show higher resistance to metal penetration than silica sand, as far as sand of a similar grain size was concerned.
4) Addition of starch had no favourable effect upon metal penetration.抄録全体を表示PDF形式でダウンロード (1187K) -
若尾 芳之, 佐藤 好男, 二木 邦夫1968 年 40 巻 12 号 p. 950-961
発行日: 1968/12/25
公開日: 2012/10/04
ジャーナル フリーA study was made on molding sand made by mixing bentonite slurry. The bentonite slurry of Na-montmorillonite showed a higher viscosity than that of Ca-montmorillonite. The relation between concentration and viscosity of bentonite slurry could be estimated by measuring the swelling and liquid limit of the bentonite. Addition of cone starch or coal flour slightly increased the viscosity of slurry. When bentonite slurry was added to molding sand instead of adding bentonite in dry flour state, it was found that the time of mixing sand could be preferably shortened by using bentonite slurry. The propeties of molding sand were, however, not influenced whether bentonite was mixed with the molding sand in dry state or in slurry.抄録全体を表示PDF形式でダウンロード (1894K) -
二木 邦夫, 太田 英明, 野崎 佳彦1968 年 40 巻 12 号 p. 962-970
発行日: 1968/12/25
公開日: 2012/10/04
ジャーナル フリーThe properties of molding sand changed as it was repeatedly used. It was caused partly due to the change in the properties of organic additives such as starch and coal flour mixed with molding sand. Starch was gelatinized after the repetition of using molding sand. The gelatinization of starch resulted in increase in hot compression strength of sand mold at 200°C. Coal flour was changed to tar, which increased the compression strength of green sand mold. As a result of experimets, it was known that starch and coal flour thus changed had preferable effect upon reducing scab defects.抄録全体を表示PDF形式でダウンロード (977K) -
前田 英三1968 年 40 巻 12 号 p. 970-977
発行日: 1968/12/25
公開日: 2012/10/04
ジャーナル フリーIn author's foundry there have been produced grey iron castings of 100 to 1,000 kg in weight for machine tool and internal combusion engine by using skin dried sand molds. For this skin drying synthetic sand which had been formerly used was found to be unfit, because it caused scab defects particularly when the weight of castings was heavier than 400 to 500 kg. to eliminate shch defects Na-bentonite, alpha starch and various cushioners are mixed with molding sand. Skin drying is made by using hot air of 270°C for 0.5 to 2 hours. The depth of skin thus dried ranges from 15 to 45 mm. For mdding facing sand is specially prepared. In reclamation of sand new sand is added to the used sand at a ratio of about 5%. of casting defects caused due to molding sand blow holes rank first, amounting for 27%, and sands rank second.抄録全体を表示PDF形式でダウンロード (991K) -
中島 源四郎, 大村 正昭, 谷本 義昭1968 年 40 巻 12 号 p. 978-985
発行日: 1968/12/25
公開日: 2012/10/04
ジャーナル フリーIn authors's foundry there are three conveyor lines of sand molding for making malleable cast iron pipe fittings which are separated into three groups according to their size. The three lines are supplied with one kind of molding sand in spite of the wide range of the size of castings to be produced. Castings of smaller sizes are produced in a way of stack molding, while those of larger sizes are made in a way of ordinary drag and cope molding. In casting in stack molds there once occurred rough surface because of the high pouring head of downrunner. To prevent rough surface core sand of a finegrain size has to be used. When fine sand is used for core making, it makes molding sand to be of poor permeability, although such poor permeability has hardly had harmful influence upon the yield of casting. However, in case of larger castings poor permeability tends to cause metal penetration particularly when the temperature of pouring is too low, the rate of pourihg being too high. This metal penetration cah be eliminated by increasing the height of feeders. The reason why metal penetration can be reduced by increasing the head height of feeders is considered as follows :
If the permeability of molding sand is low, the pressure of air in the cavity of the mold will be increased to a very high level during pouring molten metal. It will promote molten metal to penetrate into sand grains. Therefore, to prevent metal penetration it is desirable that casting design is made in such a way that the feeder is last to be filled with molten metal after the casting being filled up.抄録全体を表示PDF形式でダウンロード (719K)
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