# A Study on the Effect of Gear Hobbing Process Parameters on the Residual Stress of the Tooth Root
## 1 Introduction
In particular, improving the residual stress of parts through machining is an effective method for realizing anti-fatigue manufacturing [11]. In terms of the aspect of the first processing process of tooth making, several scholars have conducted research on the influence of machining parameters on surface residual stress. [PERSON] et al. [12] studied the effect of machining parameters on the surface residual stress by establishing a simulation model of friction disk gear pinion shaping. After optimizing the machining parameters by this method, the residual compressive stress at the tooth base increased by 203.13%, which significantly improved the fatigue life of the friction disk gear. [PERSON] et al. [13] examined the tangential, radial, and axial residual stresses of large gears during milling through different processing parameters and revealed that milling speed, feed rate per tooth, and milling width all affected the residual stresses on gears. [PERSON] et al. [14] explored the residual stress in the tooth shape direction during ultra-high-speed hobbing, and the results indicated that when \(V_{c}<800\) m/min, the residual tensile stress increased with the cutting speed; nevertheless, when \(V_{c}>1000\) m/min, the residual compressive stress dominated and increased with the cutting speed. These findings demonstrate that process parameters significantly impact the residual stress of gears during the first machining process from the tooth embryo to the gear. Analytical methods and finite element simulation methods are commonly used to study machining residual stress. However, these methods simplify the coupling factors of actual machining and cannot cover all the actual conditions, which will significantly impact the research results. Therefore, the most intuitive way to obtain real machining results is through the experimental method. [PERSON] et al. [15] conducted a study on the influence of process parameters on machining residual stress using experimental methods and analyzed the formation law of machining residual stress. [PERSON] et al. [16] investigated the impact of different process parameters on the residual stress of machining through the experimental method and analyzed the conditions for obtaining residual compressive stress. [PERSON] et al. [17] studied the mapping relationship between process parameters and residual stress using experimental methods. These examples demonstrate that the test method has been widely utilized in examining the relationship between process parameters and residual stress. In conclusion, existing research on residual stress in gears primarily focuses on the influence of grinding process parameters on the residual stress of the gear during the final machining and rarely considers the influence of process parameters on the residual stress in the first machining process of gear making. Therefore, it is crucial to investigate the influence of process parameters on the residual stress in the first process of tooth making. Gear hobbing is the first process of gear making, and the residual stress of the tooth root is the key factor affecting the performance of the gear. As a consequence, this paper aims to explore the influence rule, relationship, and interaction between gear hobbing process parameters and root residual stress through experimental analysis. The findings from this study will serve as a foundation for enhancing root residual stress and improving the manufacturing technology of gears to withstand fatigue.