Forging blank is the first link in the processing and manufacturing of large helical gears. The main work is to forge raw materials into blanks that can be made into helical gears. There are three main blank making methods, namely:
1) Directly use round steel as blank (rarely used, unimportant, commonly used for helical gears);
2) This method is adopted for forging blank – important helical gear, because it has the best microstructure and performance;
3) Cast steel blank – generally used for the manufacture of large helical gears.
The forged helical gear blank has high hardness and unstable internal structure, resulting in poor mechanical properties and difficult later cutting processing. Therefore, it is necessary to heat treat the blank to improve the quality of the blank. Heat treatment processes mainly include normalizing, tempering, annealing and quenching. Each kind of focus is different, which needs to be selected according to the material characteristics of helical gear.