巻号一覧
後続誌
46 巻, 2 号
選択された号の論文の6件中1～6を表示しています
- |<
- <
- 1
- >
- >|
研究論文
-
近藤 靖彦, 磯谷 三男, 安江 和夫1974 年 46 巻 2 号 p. 101-109
発行日: 1974/02/25
公開日: 2012/09/20
ジャーナル フリーType-D graphite irons cast in metal molds showed high strength when it was annealed to ferrite matrix. This investigation is concerned with the influence of manganese and sulfur on tensile strength, hardness and structure of type-D graphite irons (3.20%C, 2.70%Si and 2.90%C, 3.50%Si) cast in metal molds. Manganese (0.33∼1.19%) and sulfur (0.041∼0.106%) were added respectively to melt at 1,530°C. Pouring temperature was 1,380°C and mold temperature was 150°C, and the molds (20φ×60φ150mm) were coated with insulating materials. Test pieces for tensile strength were annealed at 900°C for 2 hours to obtain a ferrite matrix.
The summary of the results is shown below:
1) Tensile strengthes of high silicon iron is about 47kg/mm2 and that of low silicon iron is about 40kg/mm2. These strength decrease respectively to 43kg/mm2 and 36kg/mm2 by adding 0.7∼0.8%Mn. But the improvements of strength are recognized by adding more than 0.06% sulfur to these irons.
2) Hardness of as-cast test piece is largely affected by manganese and sulfur. In case of ferritic irons, the influences of these elements are little, and high silicon iron is Hv=165∼185 and low silicon iron is Hv=145∼165.
3) Mechanical properties of ferritic irons depend on graphite morphology due to the influence of manganese and sulfur. Mechanical properties have close relation to the area ratio occupied by type-D graphite in the cross-section of test pieces.
4) Graphite structure of the zone near the surface of the test pieces is only of type-D graphite regardless of manganese or sulfur. Some type-D graphites show globular shape on two dimentional array, but globular type-D graphite is about 1μ in length and is interconnected with each other.抄録全体を表示PDF形式でダウンロード (1320K) -
大和田野 利郎, 西村 正之1974 年 46 巻 2 号 p. 110-115
発行日: 1974/02/25
公開日: 2012/09/20
ジャーナル フリーThe authors have studied the isothermal ferritization of the uni-directionally forged spheroidal graphite cast iron.
The results obtained are summarized as follows:
1) Ferritization is appreciablly accelerated by forging. The acceleration of ferritization is attributable to the increased surface area of graphite particles in unit volume of the iron.
2) Graphite nodules in iron are flattened by forging, so that the ferritization in severely forged iron can be regarded as a one-dimensional diffusion process.
3) The growth rate constants of ferrite layer obtained from the fractions of ferritization in iron and from the thickness of ferrite layer in severely forged iron coincide well with each other, and vary with the mode of transformation, -direct or indirect−, the ferritization temperature and the chemical composition of the iron.
4) When Johnson-Mehl's equation
p=1−exp(−k tn)
is applied to the isothermal ferritization of spheroidal graphite cast iron, n is about 0.7∼0.8 for the unforged iron and the value gradually drops down to 0.5 by increased forging.抄録全体を表示PDF形式でダウンロード (673K) -
椙山 正孝, 梅田 高照, 児玉 英世1974 年 46 巻 2 号 p. 116-123
発行日: 1974/02/25
公開日: 2012/09/20
ジャーナル フリーIn general, castings solidify with a dendritic structure and the morphology of dendritie and its spacing are dependent on the cast material and the conditions of casting. The dendritic structure and variation in concentration of the solute element govern the propertisoef castings. Accordingly, deeper understanding of the factors affecting the solidification of castings and the resultant segregation are needed.
One aim of this study has been to clarify the effects of growth condition and solute element on the morphology of dendrites, and the primary and secondary arm spacing. The second aim has been to provide a quantitative and qualitative understanding of dendritic structure in order to study the identity of the dendritic structure which results in microsegregation.
The results obtained are as follows.
1) The dendrites of Cu-4∼12%Sn alloys grow like plate within the range of the cooling velocity obtained by this experiment. The morphology of these dendrites changes from a simpler shape to more complex one by either increasing the Sn content or decreasing the cooling velocity.
2) The relationship between the primary dendrite arm spacing, the content of Sn and cooling velocity was obtained as follows:
dp=1.10√C0/Va
dp; primary dendrite arm spacing (mm), C0; Sn content (%), Va; average cooling velocity.
3) The secondary dendrite arm spacing increases with decreasing cooling velocity, but is little affected by Sn content. This relationship is obtained as follows:
log ds=−0.26logVa−0.02logC0+2.4
ds; secondary dendrite arm spacing (μ).
4) The eutectoid phase (α+δ) precipitates independent of cooling velocity in Cu-10 and 12%Sn alloys, but in Cu-8%Sn alloys it precipitates at locations of low cooling velocity, and is not observed in Cu-4 and 6%Sn alloys.抄録全体を表示PDF形式でダウンロード (1076K) -
大中 逸雄, 喜多 幸雄, 千々岩 健児1974 年 46 巻 2 号 p. 124-130
発行日: 1974/02/25
公開日: 2012/09/20
ジャーナル フリーThis paper reports on the cooling of molding sand by vibrating fluidized bed. There have been very little studies on this theme.
The experiment has been done using the unsteady state cooling method which cools the heated dry sand or heated wet sand in a fluidized bed in a 105mm transparent pipe vibrated by electromagnetic vibrator. The tested frequency and displacement amplitude range was 6∼30Hz and 0∼4mm (half amplitude), respectively.
The temperature of the fluidized bed and the exhaust gas was measured by thermocouples and the heat transfer coefficient between the gas (air) and the sand particles was calculated from the values obtained.
The results are as follows.
1) Suitable vibration of the fluidized bed to an adequate amount increases the heat transfer between the sand and the cooling air.
2) The vibration effect is large when the Reynold's number (Rep) for the particle is small.
3) There is an optimum frequency and amplitude to increase the heat transfer. In this experiment vibration of 10Hz and 2∼3mm amplitude applied to the fluidized bed of the sand with 0.6mm mean diameter grains increased the heat transfer by 4∼5 times that of fliudized bed without vibration at Rep=20.
4) The heat transfer coefficient of the fluidized bed without vibration was similar to the Frantz's equation (Nu=0.016Rep1.3Pr0.67) or Sugiyama's equation (Nu=0.008Rep1.53).
5) The fluidization without vibration of the wet sand was very difficult.
6) Vibration fluidized the wet sand and the sand was very rapidly cooled compared with the dry sand.抄録全体を表示PDF形式でダウンロード (756K) -
国安 義明, 横山 収吉, 松谷 外志成, 上田 勝則1974 年 46 巻 2 号 p. 131-137
発行日: 1974/02/25
公開日: 2012/09/20
ジャーナル フリーFundamental problems in automating the hot chamber die casting machine have been investigated by the authors since 1960 and the first automatic machine was completed in 1964. In our die casting shop, many hot chamber die casting machines are now being operated by means of the falling system. In this report, the automatic drop and/or falling systems of casting are mainly described. There are still many fundamental problems in the automatic operation of the die casting machine. For example, the automatic spraying system of the die lubricant is a difficult problem. With respect to design and manufacturing of dies, the hardness, draft and polishing of die cavities must be carefully considered and in relation to the die casting operation the temperature control of dies is very important.
The authors have also described a method of preventing the metal dribble from the sprue hole which is an obstacle in the automatic operation, and the special ejecting system of castings for dies without the double ejection system.
Moreover, the authors have described the integrated cast-trim operation system that authors have developed.抄録全体を表示PDF形式でダウンロード (978K) -
曽我 政雄, 藤森 英一, 中田 進一1974 年 46 巻 2 号 p. 138-143
発行日: 1974/02/25
公開日: 2012/09/20
ジャーナル フリーTest coupons attached to large steel castings occasionally show the brittle fracture which is called rock candy fracture. This brittle fracture goes along the primary grain boundary. Usually this primary grain boundary disappears by heat treatment, but it often remains even after heat treatment and becomes brittle. In order to clarify the causes, the influences of dimensions of castings, heat treatment conditions and chemical composition on the mechanical properties and the state of fracture were investigated.
The results obtained were summarized as follows:
1) Rock candy fracture originated along the primary grain boundary which was appeared by an etchant of 50% HCI aqueous solution.
2) When the cooling rate in molds was 2∼5°C/hr, rock candy fracture was likely to occur.
3) The higher the annealing temperature was, the lower the rate of rock candy fracture got, and moreover the fracture of the test piece heated at 1,200°C was ductile.
4) Under a given cooling rate there were critical contents of Al and N at which rock candy fracture occured. Therefore, rock candy fracture could be prevented by decreasing Al or N contents.
5) It was concluded that rock candy fracture occurs by the precipitation of AlN at the primary grain boundary which makes the boundary brittle.抄録全体を表示PDF形式でダウンロード (826K)
- |<
- <
- 1
- >
- >|