Casting process design and production practice of 360m2 sintering trolley intermediate 4

Sixth, quality testing

1. Surface quality and appearance dimensions

The castings should be smooth and smooth, without large sanding, shrinkage holes and other casting defects that seriously affect their performance. The dimensions meet the design requirements.

2. Intrinsic quality inspection (see Table 7)

Seven, analysis and discussion

(1) Resin sand molding, core making, casting (core) without drying, simplifying the production process, and the sand strength, gas permeability and heat collapsibility are better than clay sand, but its concession is poor, so that the casting The internal stress accumulated during the shrinkage process increases, and the tendency to increase cracking must be eliminated by post-sequential low-temperature annealing.

(2) Due to the poor thermal stability of the resin sand, the surface of the core may be partially peeled off during the casting process, and the surface layer of the core may be partially peeled off, which may cause the surface of the casting to adhere to the sand. Therefore, the tightness of the core and the quality of the paint are grasped. And it is very important to control the pouring speed.

(3) Using the self-shrinking action in the solidification process of ductile iron, supplemented by shrinking neck small riser and a large number of venting holes, it can ensure the effective feeding of the castings, and timely discharge the internal gas to avoid large castings. Casting defects such as shrinkage cavities and pores.

(4) Our company produced a total of 326 intermediate castings for 360m2 sintering machine trolleys in May 2006, with an overall pass rate of over 97%. The main reason for some waste products in the production process was that the molds were not opened according to the specified size and position. The riser causes a large area of ​​shrinkage in the casting at the riser. In addition, because the molten iron is smelted and kept in the furnace for too long, the molten iron peroxidation and some elements are burned (or increased), causing large fluctuations in chemical composition, affecting its microstructure and mechanical properties.

(5) The samples used for chemical composition analysis are cut and sampled, and the carbon is burned during the processing, which results in a large deviation between the carbon content analysis result and the control composition.

(6) It can be seen from the quality inspection data of all trolley intermediates produced that the increase of Mn content within a certain range has certain advantages for improving the tensile strength, but at the same time it reduces the elongation, so the Mn element content is controlled well. It is very important to obtain good comprehensive mechanical properties of the casting.

Eight, the conclusion

(1) Resin sand replaces the clay sand shape, and uses a reasonable modeling process to cast 360 m2 sintering trolley intermediates. The surface roughness of castings is reduced, casting defects such as sand, pores and shrinkage holes are significantly reduced, and labor productivity is improved. .

(2) The metal mold replaces the wood mold shape (core), which has high production efficiency and small deformation of the pattern, which ensures the dimensional accuracy of the casting.

(3) Strengthening quality control in the production process is a prerequisite for obtaining high quality castings.

(4) Reasonable smelting and spheroidizing treatment processes are the key to obtaining high intrinsic quality.

(5) The casting process adopted by our company is feasible in production practice and can provide reference for the casting of large complex ductile iron castings.

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