1. Effect of pre heat treatment on cylindrical gear deformation
Before 2010, our company adopted the ordinary normalizing method for the pre heat treatment of gear blanks, and after 2010, the isothermal annealing method was adopted for automobile gear blanks The influence of two pre heat treatment methods on the deformation of carburized cylindrical gears was also a subject I studied at that time. The scheme is: the gear blanks with the same heat number and part number are pre heat treated in two ways, and processed in the same cold and hot processing methods after inspection. Finally, the deformation data of this batch of cylindrical gears are measured and compared, so as to analyze the contribution of isothermal annealing to controlling the deformation of cylindrical gears.
2. Influence of equipment and process on cylindrical gear deformation
For the batch production of truck cylindrical gears and the high requirements of their heat treatment, the carburization and quenching of such parts must be carried out in the controllable atmosphere equipment with more accurate temperature control, carbon control and good process repeatability. However, even in the same controllable atmosphere equipment, for the cylindrical gears of the same batch of materials processed in the same batch, there are different charging methods, different carburization process parameters, different quenching cooling time, speed and mixing methods, All have different degrees of influence on the final cylindrical gear heat treatment deformation, which is also the subject that our heat treatment technicians have been exploring. Therefore, for different parts, we should formulate reasonable processes and constantly revise the processes in practice, in order to finally meet the high-precision requirements of truck cylindrical gears.
The scheme to study the process influence is to select a thin-walled part with high deformation requirements and great process difficulty, and study the influence of different charging methods, different carburizing processes and different cooling methods on its carburizing and quenching deformation.
3. Effect of material hardenability on cylindrical gear deformation
The material hardenability has a great impact on the deformation of cylindrical gears. Therefore, our company has also changed the steel procurement method of buying everywhere in the past, and gradually transferred to the designated steel plant to purchase steel in order to stabilize the whole product quality. For the steel for heavy truck cylindrical gear, our company cooperates with the designated steel factory to apply 20CrMnTiH steel with convenient procurement and moderate price to the manufacturing of this kind of cylindrical gear.
To study the influence of material hardenability on the deformation of cylindrical gear, the test scheme is to use 20CrMnTiH limited hardenability steel on three different types of cylindrical gears of heavy trucks of our company, and make a deformation comparison test with the same cylindrical gear made of conventional 20CrMnTi steel under the same manufacturing conditions, and use the final data to illustrate the influence of material hardenability on the deformation of cylindrical gear.