Gear deformation is affected by many factors. In order to effectively avoid tooth shape deformation during heat treatment and reduce the possibility of deformation, technicians can take the following measures.
1. Scientific selection of gear materials
In the process of gear heat treatment, the hardness ofis the main factor affecting gear deformation, so it is necessary to select the appropriate gear material scientifically. In order to effectively reduce the possibility of gear deformation, the gear material with high hardness should be selected, because the modulus and accuracy of the gear will affect the hardness of the raw material, such as 20 CrMnTi steel, which is commonly used in our country. The material has large difference in grain size, and the characteristics of uneven grain make it prone to uneven deformation during heat treatment. Therefore, when choosing the heat treatment process, we should also consider the performance characteristics of the material itself.
2. Reasonable gear design
To demonstrate the gear structure, first of all, it is necessary to ensure that its performance meets the use requirements. Secondly, it is necessary to fully consider the possible deformation of the gear in the heat treatment process. According to the specific requirements, the design of gear structure should follow the principles of uniform distribution of workpieces, intuitive appearance, uniform tooth surface, effective reduction of uneven stress, avoidance of impedance and cooling heating. Parts with uniform and symmetrical wall thickness shall be designed. In the process of processing, when the wall thickness of the workpiece does not meet the corresponding requirements, the thin workpiece is heated rapidly in the heat treatment process, which increases the possibility of bending, so this kind of situation should be avoided as far as possible.
3. Selection of appropriate heat treatment process
The gear should be cooled with a suitable medium. For quenching agent, the most important thing is temperature control. At the same time, when selecting quenching agent, the characteristics of gear material should be considered. In order to improve the hardness of gear workpiece and the quality of gear products, it is necessary to use lubricant for lubrication and add appropriate additives. The oil temperature of quenching medium is often uneven in the actual heat treatment process, which eventually leads to tooth deformation. Therefore, the technicians should control the heat treatment equipment to ensure that the workpiece is heated evenly in the process of treatment, and use hot oil for treatment.
In order to reduce the influence of forging process on gear heat treatment, heat preservation treatment of equipment after forging can effectively prevent gear deformation caused by stress distribution. The heat treatment after forging can effectively prevent the deformation caused by uneven stress distribution.
4. Improve the quality of machining
Because the deformation of heat treatment process itself has a certain regularity, technical personnel must summarize the regularity of gas deformation, and deal with it in the production process, and put forward effective prevention and control scheme; In order to improve the heat treatment quality of gears, the inverse variables are often made in advance; At the same time, considering the non-uniformity of thickness and shape, asymmetry of workpiece, secondary processing and other factors, the machining allowance of gear should be adjusted before heat treatment, so as to effectively control the fluctuation of surface quality of gear after heat treatment.