Using a midget cupola (200 mm I. D.), the influences of ordinary tuyères (various sizes and shapes as shown in Table 1) upon the distribution of temperature, pressure and CO₂ per cent in furnace have been investigated. Metals were not charged but only coke was burned.
  Temperature, pressure and CO₂ per cent on the tuyère side (A) and on the opposite side (C) were measured respectively at several holes, which were prepared on the furnace wall between the tuyère level and the top of furnace. The results obtained are as follows : —
  (1) For the same tuyère, pressure on A side differs from that on C side only at tuyère lebel, and from a slightly upper portion above the tuyère level to the top of furnace no pressure differences exist.
  (2) When the sectional area of tuyère at the inside wall of cupola is small, the A side pressure at tuyère level rises remarkably. It is thought that the cause of this pressure rising is due to the transformation of velocity head, which is high in this case, into pressure head. This tendency is not remarkable when small sized coke is used.
  (3) When the type of tuyère is charged, the pressure distribution is also changed to some extent, but it's cause is not yet cleared.
  (4) Pressure in furnace is generally increased with the decreasing of coke size or increasing of blast rate.
  (5) Ratio of pressure drop at tuyare (P₁) to total pressure drop (P₁+P₃), where P₃ is pressure drop at furnace shaft, decreases rapidly with the decrease of tuyère ratio, and is almost negligible when tuyère ratio is about 5.
  (6) Pressure drops P₁ and P₁+P₃ for convergent tuyère are both almost equal to those for the same shaped divergent tuyère.
  (7) Irrespective of kinds of tuyare, temperature distribution at A side differs considerably from that at C side, and especially at the portion close to tuyère, temperature of A side is remarkably higher than that of C side.
  But it seems that the temperature distributions at the same side for various kinds of tuyères have no differences each other.
  (8) Distribution of CO₂ per cent in furnace has the same tendency as that of temperature.
  (9) From the above mentioned, results, it is justly said that, in spite of the differences in size or shape of tuyère, blast is unable to penetrate deeply into furnace, and thate the combustion of coke is vigorous only where the parts close to tuyère.
  (10) Both the distribution of temperature and CO₂ per cent in cupola are much more influenced by the blast volume or the coke size than the differences of the types of tuyères.

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  In order to obtain high quality cast iron, the combustion condition in cupola must be kept highly uniform and high temperature.
  Namely, attentions must be given to the following items.
  1) Should lessen the variation of resistance in cupola shaft and maintain constant blast pressure in wind box. Strict control must be performed on the size and quality of charging metals and coke.
  2) Should blast a costant blast volume irrespective of the resistance in cupola shaft.
  To achieve this, the use of a turbo-blower having a surplus capacity and practise the automatic control of blast volume is much effective than the improvement of low capacity turbo blower, though, this can be achieved the aim for some extent.
  3) 80 per cent of blast pressure, the average blast pressure in wind box, is consumed by the resistance at tuyères and bed coke, therefore, if the resistance at tuyères is small enough the variation of resistance can be thought as the variation of resistance as bedcoke.
  4) Though the melting is conducted with the aim to obtain similar specifications of cast iron, the chemical compositions of the melt such as carbon and silicon and the chill depth will vary according to the size of coke if it has the same quality.
  5) Coke size must be determined considering the characteristics of the molten metal and the size of cupola.
  In the experimental melting, the most uniform melt in its quality has obtained when the coke size is 60∼80 mm, blast volume 20 Nm³/min, and the blast pressure in wind box is 200∼220 mm in water height.
  6) Carbon dioxide per cent in waste gases is varied according to the difference of coke size, although the operating condition and the blast volume are constant.
  7) Quality of the melt can easily be controlled if the coke size is controlled.
  8) If the melting is conducted without making uniform coke size, the combustion will locally be uneven and thus the effect on the melt becomes unequal.
  9) It is impossible to attain the total surface area of coke uniformly, though the strict control is performed on the coke size. Therefore it is unavoidable the variation of carbon dioxide which is contained in the waste gas though the blast volume is kept constant.
  10) The shape of coke is desired to be globular and chunky, which shows little variation of surface area.
  11) If preferable cupola operation is conducted, even the iron having rather low tensile strength as 19∼20 kg/mm³ shows extremely uniform grain size and has good resistibility against pressure or wear. The chip of this kind of iron comes out continuously with whirling.

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  Succeeding to the fundamental studies on the construction of cupola and the wind flow in cupola, the experiment to produce high quality cast iron was made this time using an experimental cupola having. the inside diameter of 500 mm.
  The points where the special attention is given in carrying out the experiment are the use of Askanian-type automatic blast control instrument and the uniformity of the shape, size and quality of the charging materials such as pig iron, steel scrap and coke as well as possible.
  The gists of the results are as follows :
  1) Pressure resistance at bed coke is considerably great and it reaches to approximately 60 per cent of the total wind pressure.
  2) Blast volume needed to combustion coke is varied according to the carbon ratio. But in this case, it generally reaches to about 9.0 m³/kg.
  3) It is preferable to operate cupola in its most effective condition, investigating the resistibility of cupola and the characteristics of a blower and a damper. In general, about 30∼40° angle of choke panel in damper is most preferable in developing the best efficiency.
  4) To obtain high strength cast iron, the melting should be performed to produce low carbon iron, by increasing the charging ratio of steel scrap and thus maintains high carbon pick-up.
  Though the percentages of T.C. or Si are the same, the iron which picked up carbon highly is superior than that of low carbon pick up in its castability and mechanical properties.
  5) As the oxidation rate of steel increases, the consumed ratio of silicon increases.
  And the consumed ratio of silicon becomes higher when carbon dioxide per cent is high.
  The yielding ratio of castings is lowered in accompany with the increasing of silicon loss.

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  This manuscript contains all-round research results on clay substances contained in molding sand. It seems that most of the studies so far made on molding sand only depend on the physical test results of the sand.
  According to the fundamental studies made by the authors on the problem of deterioration of molding sand, it was found that the main factors which affect on deterioration are inferiority of thermal resistibility and the variations of the characteristics of soil.
  Especially, the change of clay substances in quality can never be missed.
  In this regard, the authors tried to ascertain the characteristics of mineralogical components of clay substances in molding sand by fundamental thermal experiments and by means of X-ray diffraction method.

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  In recent years, the utilization of synthetic resins for the binders of molding sand becomes prevailing in Japan. The feature of the application of these materials is the thermosetting properties, so that the thermosetting resins are exclusively used. Consequently, the mold should be hardened by heating.
  This experiment was carried out so as to harden the mold at room temperature by using polyester resins, whose inherent character is the “room temperature hardening property”. In this process, the curing of mold can be made at room temperaure, and this results in the possibilities of making the shell molds from a wooden pattern.
  The experimental results are as follows :
  1. Usually, the amount of resins in sand mold are relatively small (a few per cent of sand weight), the exothermic reaction of hardening of polyester resins is prevented by the adsorption of heat by sand grains. Owing to this reason, the rate of hardening of sand mold is lowered rapidly when the temperature of atmosphere is below 30°C.
  2. As a catalyst of room temperature hardening, methyl ethyl ketone peroxide (Lupersol DDM) is used. In this case, the maximum rate of hardening is obtained at 30°C. Whether the temperature of atmosphere is higher or lower than 30°C, the strength of the sand mold is inferior.
  3. Relatively higher percentages of DDM catalyst and cobalt naphthanate promoter are necessary for this process than those are ordinarily used. The best result is obtained by the addition of 3 to 7 per cent of DDM catalyst and 0.75 per cent cobalt promoter.
  4. For high temperature hardening, the benzoyl peroxide (B. P. O.) catalyst is used, and good results are obtained by hardening the mold at 200°C.
  5. The penetration test is made by pouring the gray iron into this new mold. In the case of B. P. O. and DDM catalyst are used, good results as well as the mold made from phenolic resins are obtained.

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