The research on heat treatment deformation control of heavy truck gearbox gear is of great practical significance and great practical value.
(1) The material selection of the gear box of heavy-duty truck requires the hardenability to ensure that the tooth surface and center of the truck gear get the specified hardness after carburization and quenching, so as to meet the use requirements of the truck gear. At the same time, it is also hoped that the hardenability band of the steel is narrow to ensure that the deformation range of the truck gear after heat treatment is small; It should also be essentially fine grain steel with high steel purity, high surface quality and reasonable element matching. Affected by many factors such as material price, 20CrMnTi is still the most widely used steel in truck gear industry in China, but 20CrMnTiH steel with hardenability has been gradually used.
(2) In order to improve the cutting performance of parts and provide good tissue preparation for final heat treatment, the pre heat treatment process of heavy truck gearbox gears has gradually used isothermal annealing instead of normalizing; The performance of heavy truck gears requires high bending fatigue strength, high contact fatigue strength and wear resistance, high strength and toughness. Therefore, the final heat treatment process of heavy truck gears is still dominated by gas carburization.
(3) The deformation of heavy truck gear after carburizing and quenching is caused by the gear in the process of heat treatment, but the fundamental reason for the deformation is the change in the shape and size of the truck gear caused by the different organizational structure and state of each part of the truck gear, the different organizational transformation order of each part of the truck gear in the process of heat treatment, or the different stresses in each part. These factors are closely related to many aspects, such as the shape of the gear, the material of the gear, the forging of the gear blank, the pre heat treatment of the gear blank, the cold working process and equipment of the truck gear, the heat treatment process and equipment of the truck gear, and so on. It is a more complex systematic problem, but for the production of heavy truck gear, the deformation control of the truck gear is an imperative productive topic, We must find a feasible way of application.