The original blank of spur bevel gear is determined according to the forging shape, size, forging method and the required volume calculated. The volume of the original blank of spur bevel gear shall include the sum of forgings and flash. Firstly, the solid modeling of the spur bevel gear is carried out by using the modeling software UG, and the volume of the spur bevel gear forging is calculated according to the solid model of the spur bevel gear. Then, according to the empirical formula, the amplification factor of the spur bevel gear blank is 1.35, and the volume of the original blank of the spur bevel gear is calculated. Because it is the optimal design of spur bevel gear blank, three blank shapes are designed, and their magnification factor is 1.35 (i.e. the same volume).
The preparation of preform of spur bevel gear should go through three steps: forming, softening annealing and lubrication.
(1) Spur bevel gear preform forming processing. The forming method of preform is mainly band saw blanking and turning. The blanking accuracy of metal band saw is higher than that of other blanking methods, and the end face is flat without bending, skew, collapse and other problems.
(2) Softening process design of spur bevel gear blank. The preforms of cold plastic deformation parts need spheroidizing annealing in order to reduce hardness and improve plasticity It is convenient for metal flow forming.
(3) Lubrication treatment process design of spur bevel gear blank. Before cold plastic forming of ferrous metals, phosphating of preforms is an effective way to reduce friction, deformation force and uneven deformation. The reasonable lubrication treatment process of blank is: phosphating at room temperature and vibration coating of solid lubricant. At the same time, good phosphating layer and solid coating effect can be achieved by strictly controlling the parameters such as free acidity, total acidity, solution temperature and solid vibration coating time.