As one of the most important components of a car, the gearbox is well-known for its ability to change vehicle speed. As we all know, from a hands-on perspective, the gearbox can be roughly divided into two types: an automatic gearbox and a manual gearbox.

The manual transmission is mainly composed of gears and gear shafts, which change the transmission ratio of the car through gear combinations between different gears, thereby achieving the goal of variable speed and torque conversion; The automatic transmission AT is composed of a hydraulic torque converter, planetary gears, and hydraulic control system, which achieves variable speed torque (engine torque) through hydraulic transmission and gear combination. It can be narrowly understood that an automatic transmission is a set of auxiliary transmission equipment added to a manual transmission to free people's hands. However, from the perspective of gear division, gearboxes can be divided into stepless transmissions and continuously variable transmissions, with clear gear division in the front and no gear division in the latter.

The main functions of the gearbox are as follows:

1、 Change the transmission ratio; The so-called transmission ratio refers to the speed ratio between the combined two gears in that gear position. The higher the transmission ratio, the stronger its power performance, such as in gears 1 and 2; The smaller the transmission ratio, the faster the car speed, such as in 5th gear or above.

2、 Enable the car to move in reverse while the direction of engine rotation remains unchanged; The principle is to add a reverse intermediate gear between the driving and driven wheels to achieve the reverse rotation of the power output shaft gear and change the direction of the power output.

3、 Realize power conversion in different states of the car, using neutral gear to interrupt power transmission, enabling the engine to start, idle, and facilitate transmission shifting or power output.

It should be emphasized that the input shaft and output shaft of the transmission are respectively connected to the clutch and transmission shaft.

On the basis of single piece ring rolling process, numerical simulation is conducted on the forming process of double piece ring rolling. By analyzing the stress-strain distribution, geometric shape, and forming size of the forming process, it is shown that the stress-strain distribution law is generally consistent with the deformation process of single piece ring rolling, and the geometric shape and forming size meet the requirements. By comparing and analyzing the material utilization rate of single and double piece ring rolling forming, it is found that the material utilization rate of the double piece ring rolling forming process is improved compared to the single piece ring rolling forming process, and the production efficiency is improved and the cost is reduced. The proposal of this process provides an important theoretical basis for future production practice