| In hardened gear manufacture, carburizing and hardening process is the mainstreamtechnology way, but the gear distortion is the prominent technical problem.The factors whichinfluence the gear distortion are quite many, including design, material and the manufactureprocess, many factors in which are influenced one another, so the distortion is difficult tocontrol and then becomes one of the technical difficulties of gear manufacture in theworld.Material and technology factors play the important part in the factors which affect thegear distortion,the dissertation contraposed 20CrMnMo,20CrNi2Mo,20Cr2Ni4,17CrNiMo6 etctypical earburizing steels,systematicly studied the effect on the distortion of forgingratio,pro-treatment, carburizing temperature, carbon potential,preheating, quenching temperatureas following:1) Effect of material and technology factors including forging ratio, pre-treatment,carburizing temperature, carbon potential, quenching temperature and preheating etc on theheat treatment distortion was studied by orthogonal test.2) The influence of hardenability on the distortion of 20CrMnMo, 20CrNi2Mo,20Cr2Ni4, 17CrNiMo6 was studied by Jominy test.3) The distortion rule of large discal gears carburized and hardened was studied bymathematical statistic method.The result of the study shows that the effect on the distortion of carburizing temperature,carbon potential and quenching temperature is very prominent; the effect on the distortion of forging ratio, pro-treatment and preheating is inapparent,but they have favorable effect in theoptimized technology;The effect on the volume distortion and shape distortion ofhardenability is increased along with the increase of hardenability;Enhancing the purity andthe uniformity of steel had a prominent effect to reduce the shape distortion of gear.Accordingto the study, the distortion would be controled preferably via the control of prominent factorsand optimized technological parameters. |
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