Growth rate of gear is the key drive screw compressor parts, work speed 2000 ~ 4000r/min, with matching motor power is 90 ~ 250kW. Such gear is divided into two types: gear shaft (length 250 ~ 350mm) and with the gear bore. Tooth width of 50 ~ 70mm, the maximum size of the radial teeth 150 ~ 385mm, modulus m = 3, precision gears 6, with 20CrMnTi steel. Drawings, design tooth surface hardness 54 ~ 60HRC, core hardness 35 ~ 40HRC. Original with the outsourcing of such gear in use in folding gear failure, the reasons for the examination and analysis of the hardness is less than the roots of teeth in mesh diffusion layer and carbide. To this end, the gear pit carburizing furnace carburizing, normalizing, quenching. Processes such as forging gear roughing →  normalizing (shape) → normalizing carburizing quenching and tempering → ?? semi-finishing  → ??inspection.

Heat treatment process: 1st in preparation for normalizing heat treatment, mainly to facilitate the forging of cutting. 2nd normalizing for the total elimination of diffusion layer in the network commentate, so as not to produce when grinding gears grinding cracks and improve performance. Used quenching oil cooling into the oil ,when the gear according to the different shape and size were used along the horizontal or vertical axis of the gear into the quench, to reduce quenching distortion.

Gear check its hardness after quenching and tempering, the tooth surface is 54 ~ 60HRC, the Ministry of the heart 35 ~ 40HRC. Outside to the inside surface of the gear microstructure of tempered marten site small granular carbide, the second layer of needle-like marten site, the center of the tempering sorbet + ferrite. Harden layer depth of 1.0 ~ 1.3mm is normal length direction of the gear deformation ≤ 0.03 ~ 0.07mm. The above drawings are up to the standards and design requirements.

The heat treatment process with more than 100 sets of gear, the processing and examination, not a gear for cracks and distortion tolerance, microstructure and hardness were also meet the requirements.