Technological characteristics of nodular cast iron in cylinder

The inlet cylinder casting is composed of flange, brace, volute and other parts of cross connection. In the study, the zoning identification is carried out according to figure 1 to facilitate the identification of each working surface of the casting. The important section (section) after casting section is shown in Fig. 2.

The main assembly mating surfaces are as follows: surface B and J – upper and lower half of the inlet cylinder, h and I – the assembly and fitting surface of the inlet cylinder and the compressor cylinder, surface G – assembly and fitting surface of the stationary blade, and surface e – intake side airway surface.

Main bearing working face: B, J, G and H are the main assembly positions, which bear the forces in the direction of tension, compression, bending and shear. The position of connecting bars in the drawing has the same requirements as the main assembly position.

Analysis of casting process characteristics

(1) It can be seen from the section section in Fig. 2-2 that the wall thickness of the casting section is greatly different, the thickness is uneven, there are many cross connection positions of wall thickness, and there are many abrupt positions of thickness and isolated distribution. These special structures have important influence on sequential solidification, balanced solidification and solidification feeding;

(2) Because of the complex structure of the casting cavity, it is usually formed by a large number of sand cores, so it is difficult to control the size accuracy. Some thin-walled positions are easy to cause wall thickness penetration quality problems due to sand core floating and other reasons;

(3) The results show that the core of casting is cantilever due to the structure of multiple threading holes, and some slender cores are prone to fracture or warpage during pouring;

(4) There is a large plane with the outline size of 4250 mm, which is easy to produce casting defects such as slag inclusion and inclusion.

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