Current status of deformation processing of helical rack

Helical rack technical requirements

The material is 18Cr2Ni4WA, length 1836mm, diameter 245mm, modulus 25, number of teeth 21.5, pitch 78.54mm, pitch deviation ±0.03mm, accuracy grade 7GK GB/T 10096-1988. The tooth surface is carburized and quenched, and the effective hardened layer is 2.50 to 3.00 mm. The quenching hardness is 56 to 60 HRC, and the core hardness is 35 to 41 HRC.

Helical rack processing route

Cutting → forging → normalizing + tempering → car → stress relief → milling → carburizing + quenching → grinding outer circle → car → grinding plane → finishing milling (tooth shape) → clamp → inspection.

Helical rack heat treatment deformation state

The rack is a long shaft type asymmetric gear carburizing member. 2.0t Giefei sealed box type multi-purpose furnace production line equipment, carburizing and quenching placed at 3 points on the tooth surface upward. As a result of the combined effects of thermal stress, tissue stress and additional stress during the heat treatment, the rack deforms greatly and is distorted. The rack deformation: the rack is warped upwards in the direction of the tooth surface, and the distortion is convex. In the 1.55~7.80mm; the facet of the facet is 0.58~1.20mm, which is concave; the length of the rack is shortened, the shortening is 0.85~1.80mm; the bar spacing is increased to different degrees, increasing by 0.40~0.78mm; The shaft diameter is inflated and the swelling is between 0.35 and 0.55 mm.