Gear hobs are generally made of general-purpose high-speed steel, with a hardness requirement of 64-66.5HRC. There are also requirements for carbide unevenness, which is preferably ≤3. The annealing heat treatment process of gear hobs made of M2 steel is as follows:
1) Preheat. Use a special quenching fixture. The preheating is generally done by drying in a well-type air furnace at about 500°C, and then preheating in an 850-87U medium temperature salt bath furnace. The preheating time is twice the heating time.
2) Heating. The heating temperature is 1225-123℃, the grain size is controlled at level 9.5-10, and overheating is allowed by level 1-2.
3) Cool down. After coming out of the oven at high temperature, it is pre-cooled in the air for a few seconds and then quenched. Gear hobs with module <5 are generally classified twice at 580-620℃ and 450℃. Modulus ≥5 are all classified isothermally, that is, they are first classified in a neutral salt bath at 580-620℃ for 2 minutes, and then transferred to 260 - 28WC nitrate salt isotherm for 1.5h.
4) Tempering. 550℃ x lh x4 times of tempering, isothermal quenching requires 4 times of tempering.
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GS-ZP-1200
