鋳物
Online ISSN : 2186-0335
Print ISSN : 0021-4396
ISSN-L : 0021-4396
26 巻, 8 号
選択された号の論文の4件中1~4を表示しています
研究論文
  • 小山 代三郎, 久保 圭史
    1954 年 26 巻 8 号 p. 405-409
    発行日: 1954/08/25
    公開日: 2012/11/14
    ジャーナル フリー
      To melt the black heart malleable cast iron, cupola, air furnace (a reflecting furnace using heavy oil, pulverized coal and gas as fuel), electric furnace (such as electric arc furnace, induction furnace) are commonly employed, either single or in combination with the other type of furnace in duplex melting system.
      The Kuwana Works of Hitachi, Ltd., to which the authors belong, is provided with the facilities for duplex melting, consisting of a combination of 7-ton cupola and 5-ton Heroult electric furnace, besides 3-ton high temperature blasting cupola and 1-ton high frequency induction furnace.
      In this paper, the authors tersely introduce how these facilities are operated and what is the difference between various melting methods currently in practice. The gists of the paper are as follows :
     (1) Applications of furnaces−from the viewpoint of production scale :
      In case of the daily melting norm exceeds 60 tons, thc duplex melting system using a combination of cupola and electric arc furnace is considered most suitable. When the norm is around 30 tons a day, either of the use of high temperature blasting cupola or the combined system of cupola and high frequency induction furnace is recommended.
     (2) Features of furnaces−from the viewpoint of quality of product :
      High-quality product is hard to manufacture by means of a cupola alone. If the melting equipment is to be used single, the high frequency induction furnace gives the most satisfactory result, and the electric arc type furnace comes next. The high temperature blasting cupola is considered to show a great deal of promise in this respect, if further improvement is performed.
     (3) Comparison of economical advantage :
      In the melting cost, the high temperature blasting cupola comes first, followed by the duplex melting system. The high frequency induction furnace, however, is not so expensive in the operation as generally held.
  • — 粒形狀の影響について —
    木下 禾大, 佐野 專一, 木下 勝行
    1954 年 26 巻 8 号 p. 410-419
    発行日: 1954/08/25
    公開日: 2012/11/14
    ジャーナル フリー
      Succeeding to the last report, the authors have studied the effect of the sand grain shape on the characteristics of moulding sands carrying experiments on its high temperature properties chiefly and have tried to derive the answer that what shape of sand grain is most suitable for moulding sands.
      The results obtained are as follows ; -
     1. The difference of sand grain shape is hardly distinguished by the test on green properties.
     2. Rounded sands have good flowability and permeability but have considerably bad porosity.
     3. Rounded sands show less high temperature expansion and less high temperature crack.
     4. The reason why rounded sands show less high temperature expansion in spite of its good flowability is that the less contact resistance of sand grains.
     5. The contact resistance of sand grains is a function of size and shape of porosity as permeability like.
     6. By measuring permeability of sands, the authors can assume the volume of expansion at high temperatures fairly well.
  • — 搗固めによる變形について —
    牛山 五介, 喜多 新男, 岡倉 常之
    1954 年 26 巻 8 号 p. 420-433
    発行日: 1954/08/25
    公開日: 2012/11/14
    ジャーナル フリー
        Influences of grain size distribution and grain shape of moulding sand on its physical properties have not yet been fully discussed owing to the complexity of multiple combinations of the factors.
        In case of adopting a new type of synthetic moulding sand, however, every foundry has to face with the problems to discuss its grain size distribution and grain shape.
        That is, in view of mouldability and stability, they seem to be the fundamental problems for a mass production system.
        In this report, several data and experiences on silica sands for steel and malleable castings which are used in our foundry, are analised and discussed.
        Especially, changes of volume by ramming were measured and compared on three kinds of different base sands containing bentonite and moisture.
        These leading results obtained are as follows :
      (1) Volume or height of a sand specimen weighing 200 g, which is given a constant ramming energy, indicates its maximum value in a constant moisture content on the curve showing the relation between specimen height and moisture.
      (2) Over 2 blows with a standard rammer, there is a proportional relation between height or volume of a sand specimen and a logarithm of the number of ramming.
      (3) Provided |b| as the gradient of the line which has been calculated by the least square method and ‘a’ as the height of the sand mass which is given two times of blow, then the former expresses the deformability in ramming per a unit ramming energy and |b|/a expresses the compactability.
      (4) The more bentonite is added the higher the |b| is. Each sand indicates its maximum value in each constant moisture on the curve showing the relation between |b| and moisture.
        In this experiment, base sand Ⅲ having an optimum grain size distribution and a subangular grain shape showed the highest value of |b| among these three sands.
      (5) In view of Dietert's Flowability, base sand Ⅲ having the largest value of |b| is thought to be related to this flowability and has smallest value of flowability. This sand is, however, considerd to have a close value to Kyle's Flowability which usually indicates an important phase of mouldability.
  • 椙山 正孝, 菊池 正夫
    1954 年 26 巻 8 号 p. 433-438
    発行日: 1954/08/25
    公開日: 2012/11/14
    ジャーナル フリー
      This study was carried out to ascertain the difference of mechanical properties between the castings made with shell moulds and the conventional sand moulds. The casting metals used were cast iron, copper alloy (85-5-5-5) and some aluminum alloys, and they were poured into shell moulds, green or dry sand moulds respectively under the same conditions. In the case of shell mould castings, the effects of back-up materials were examined.
      By measuring the cooling rate and observing the macro-structures, it was found that the melt poured into sand mould solidified more quickly and much finer grain structure was formed compared to that of shell moulds. In spite of the coarser macro-structure, the mechanical properties of certain shell mould castiugs were comparatively better than those of the sand mould castings. These experimental results seem to attribute to the fact that the cooling rate in the shell mould backed up with appropriate materials contributes to the directional solidification of alloys.
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