The graphitization effects of P and S added to pure 4.1% C ferro alloys were studied by micrographic examinations. Chill cast specimens were heated at various times and temperatures.
  The fact that the addition of P facilitates the graphitization of cast iron was confirmed by this experiment and this corresponded to the results taken by former investigators. But it was found out that S also contributed to graphitization. The graphitizing temperatures were lowered by the addition of 0∼0.3% S. When more than 0.5% S was added, graphitizing temperatures were increased again. (viz. There was minimum temperature between 0.2∼0.5% S range.) But when 1.0% S was added the temperatures became lower than that of 4.1% Fe-C alloy.

抄録全体を表示

  The nature of the Shima sands stratum was investigated.
During 2 years (April 1951∼March 1953), about 5,000 tons of Shima moulding sands were mined. The variation of grain size distribution, in this period, was very small but the clay content was considerably variable in spite of careful mining. These variations seems very fundamental problem to make synthetic moulding sand.

抄録全体を表示

    To study the mechanism of sintering of silica sand for steel castings, the following experiments were performed. Various silica sands were heated at various temperatures up to 1400°C for several hours. After they were cooled, the degrees of sintering were measured. The degree of sintering means the resistance of sintered sand against a slender rod which was penetrated into sand by impact.
    The results obtained were as follows :
  (1) Silica sand of fine, grain size was easily sintered than coarse one.
  (2) Silica sand containing water was easily sintered. This effect was more remarkable for fine sand than for coarse one.
  (3) Calcium oxide and iron oxide contained in sand promoted the sintering, but the effect of the former was more remarkable than the latter.

抄録全体を表示

    It is an extremely important operation to control the blast volume in the melting operation with a cupola and this has close connexions not only to the tapping amount, the combustion condition in cupola, the save of fuel and other materials to be needed but also to the carburization percentage of carbon and the loss of silicon that seems to have great influences on the qualities of molten metal.
    On the actual operation of melting, both the air resistance and the air pressure in cupola are affected very much owing to the charging procedures of materials and the variation of electric source, therefore, it is almost impossible to keep the blast volume properly by the human ability.
    If this very delicate control of blast volume is fairly accomplished, then the percentages of carbon and silicon contained in molten metal can be controlled desirably and the molten metal which will produce the optimum chill depth when cast can be attained.
    The following results have been taken by employing the Askanian-type blast volume control instrument to the cupola having 1500 ton capacity which is installed in our factory.
  1. The variation of blast volume was ± 0.1 N m³/min against to the total blast volume of 20 N m³/min.
  2. The percentage of CO₂ contained in top gas was retained in 12.0∼12.5% after the condition of melting operation was stabilized, and the proper volume of blast could be supplied into the furnace corresponding to the test results of chilled pieces. And this adjustment could be made easily by remote control.
  3. By giving the adequate control on both materials and blast volume, the molten metal which produces the most preferable chill depth to the desired castings was attained.
  4. The adoption of the high temperature melting operation to this procedure was possible and the measured tapping temperature of the molten metal by an optical pyrometer was 1510∼1530°C. (the manipulated temperature value plus 110°C)
  5. In the heretofore carried operation, the residual percentage of products was 85∼92 per cent, but it was developed to 92∼95 per cent by the installation of an automatic blast volume controller.
    Especially, the percentage of the rejected goods due to the lack of hydraulic pressure resistance or the defective horning finish was decreased down to 1. 2 per cent.
  6. The material cost this time was reduced to 10 per cent compared with that of commonly used operation by adding 40∼50 per cent of steel scrap to pig irons.
  7. The blast volume was kept almost constant and the tapping amount was increased 12 per cent. Consequently, the melting time was shortened.
  8. Even if the percentage of steel scrap addition becomes greater and the amount of coke to be used is not increased, the fear of the decrease of melting temperature and the oxidation of molten metal can not be introduced. The save of the amount of coke is accomplished at the rate of approximately 12 per cent.
  9. The amount of lime stone was also saved 40∼50 per cent owing to the applications of the techniques of high temperature melting and remote controlling of blast volume.
  10. The number of cleaning the tuyére was reduced by controlling the blast pressure and tuyére sizes.
    As mentioned above, the employment of the automatic blast volume controlling instrument facilitates the melting operation with a cupola. (T. M.)

抄録全体を表示

  Using a midget cupola (I. D. 60 mm), the author investigated the effect of coke size on cupola operation. The gist of the result obtained are as follows :
 (1) CO content in the effluent gases increases with the decrease of coke size. Owing to the increasing surface area of coke, the reaction between C and CO₂ gases accelerates very much.
 (2) At the beginning of operation, the size of bed coke has influence upon the composition of effluent gases. But the bed coke above tuyéres is burned out and gradually replaced by the charge coke, which seems to give an influence upon the gas composition thence-forth.
 (3) From the view-point of the composition of effluent gases, melting rate should be theoretically increased with the decrease of the coke size. But practically, in case of too large or too small coke size. it is less than the theoretical case on a count of the unsmoothness of the operation.
 (4) By the same reason, tapping temperature is also lowered in case of coke size is too large or too small.
 (5) Greater blast pres ure is required with smaller coke size because of the higher resistance of air passage.
 (6) Chemical composition and properties of molten iron are scarcely influenced by the size of coke, but are extremely influenced by the quality of coke and coke ratio. But proper size of coke must be selected for the effective operation.

抄録全体を表示