抄録
Truck-frame of rolling stock made by one block steel casting has recently been manufactured in large quantities and, as the problem on casting in relation to it, it is required in practice to clarify the tendency of deformation by shrinkage in truck-frame of rolling stock made by one block steel with reference to side-frame, transom and end beam of truck parts. Generally the cross-sectional thickness of truck-frame is approx. 18 mm, the weight of casting is 1,400∼2,400 kg and casting-size is approx. 4,000×2,000×800 mm. In ordinary steel casting, it was cast at the pouring temperatures of 1,520∼1,540°C and we investigated the deformation of itsas-cast state and that of after annealing. Casting chart of truck-frame is shown in Fig. 1 and we used green mould assembled cores. The complete product of a truck-frame is shown in Photo. 1. The results investigated the tendency of shrinkage deformation of this truck-frame are illustrated in Figs. 2∼4. The built up truck-frame, not one block steel casting, is shown in Photo. 2, and as for a parts of which, the side-frame, is shown in Photo. 3. The same tendency of deformation shown in Fig. 5 can be observed and such a tendency can be found in the side-frame of the truck-frame made by one block steel casting because of the resemblance of casting condition. A tendency of deformation in side-frame as the parts, is shown in Fig. 6. The followings can be derived from the investigation. (1) If the casting condition is almost similar, we can presume that the shrinkage deformation of one block casting in some degree from the shrinkage deformation condition of the independent steel casting which consists of each part of the casting, and such a case like this, general rules of shrinkage deformation of casting and experiences are very useful for us. (2) We found less resistance of casting mould against shrinkage deformation, less occurrence of cracks and much deformaton, in a green sand mould assembled with many cores than in dry sand mould. (3) Knowing that a tendency of shrinkagedeformation and its deformation quantity, we can decide measuring scale in accordance with each part and after doing so, combining various measuring scales suitably, we can limit the deformation quantity within the range of tolerances. These matters are so noteworthy points that we can apply them largely in order to get the products of less cracks and of less shrinkage deformation in case of manufacturing one block steel casting hereafter.
