As the starting point of the casting forging compound forming process, whether the casting process design and the casting defect control measures are reasonable directly affects whether the casting forging compound forming process can be successfully applied in the manufacturing and production of spiral bevel gear.
Casting process analysis
The technical requirements, production conditions, production scale and structural technology of casting products should be fully considered in casting process design. According to the established technical roadmap, in the last section of this paper, the size and shape of the preform of the hot die forging of the spiral bevel gear are determined, which is equivalent to the target product diagram of the casting process stage of the spiral bevel gear. For the casting process analysis of spiral bevel gear blank described in this paper, not only the quality requirements of the subsequent closed hot die forging process for the gear blank, but also the material composition, technical requirements, casting process selection and structural characteristics of the gear blank casting and many other factors need to be considered.
Effect of material composition on properties of castings
The element and content of alloy have great influence on the quality of steel casting and the determination of casting process. The casting material used in this paper is common gear steel 20CrMoH. Different kinds of elements have different effects on the properties of castings:
1.Silicon silicon is usually distributed in the metal structure in the form of solid solution, which can significantly improve the hardness and yield strength of the metal, etc. during the hot processing of steel containing Si, a dense SiO2 film will be formed on the surface to prevent the steel from further oxidation;
2.Manganese Mn / chromium Cr / molybdenum Mo are all beneficial elements of low alloy steel. As strengthening phase, they can greatly improve the mechanical properties (such as strength, hardness and wear resistance) of steel under hot working condition;
3.Sulfur s and phosphorus P are harmful elements in steel. (1) If the content of phosphorus is too high, it is easy to form Fe2S precipitate and cause cold embrittlement of steel, and the mechanical properties of steel will be affected; (2) although sulfur can improve the cutting performance of steel, if the content is too high, it is easy to form sulfides such as FES, which will lead to the segregation of steel and reduce the mechanical properties of steel. In order to improve the forming quality of castings, the content of S and P should be strictly controlled.