## 7 Conclusions  
In this paper, a curved toothed cylindrical gear adapted to the traction of higher-speed moving train sets is proposed and designed. A parametric model of the arc toothed cylindrical gear transmission system is established by using CREO, the dynamic contact analysis of meshing and acoustic response characteristics are carried out under the continuous working condition of the moving train set, and the maximum contact stress and radiated noise under the continuous working condition are obtained. On this basis, a comprehensive reshaping scheme of the tooth profile combined with the radius of the curved-tooth line is designed, and the virtual reshaping prototype of gears is reconstructed by CREO and MATLAB. The simulation analysis of the modified arc gear cylindrical gears is carried out to compare the dynamic contact characteristics of meshing and radiated noise of the modified arc gear cylindrical gears before and after the modification. The research process includes the reconstruction of a virtual trimming prototype of a gear. The adopted gear parameters were repeatedly verified and tested to ensure the  
Figure 18: Sound pressure level curves at each point after trimming. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Comparison Item**} & **Before** & **After** & **Magnitude of** & \\  & **Modification/dB(A)** & **Modification/dB(A)** & **Change/dB(A)** & **Rate of Change (\%)** \\ \hline point 1 & 88.0976 & 71.1615 & \(-\)16.9361 & \(-\)19.22\% \\ point 2 & 100.3000 & 79.1834 & \(-\)21.1166 & \(-\)21\% \\ point 3 & 94.5201 & 71.3236 & \(-\)23.1965 & \(-\)24.51\% \\ point 4 & 103.3880 & 90.4435 & \(-\)12.9445 & \(-\)12.53\% \\ point 5 & 90.6484 & 70.9458 & \(-\)19.7026 & \(-\)21.75\% \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Comparison of radiated noise at each field point before and after the shape modification. accuracy of the trimming, including the selection of the size of the radius of the curved-tooth line, which was also subjected to several experiments, and a suitable value was finally determined. In this paper, several analysis methods, including dynamic contact analysis and acoustic response characterization via finite element boundary element method, are used to simulate the dynamic behavior and acoustic response of a real gear system. Finally, the reliability and accuracy of the trimming method were verified via dynamic contact analysis and ACTRAN for noise prediction. These analytical results confirm the reliability and accuracy of this reshaping scheme. In summary, the research results indicate that the repair program has achieved favorable outcomes, effectively alleviating contact stress and reducing radiation noise, thereby laying a theoretical foundation for the development of the new generation of high-speed EMU traction gear transmission systems. The following conclusions can be drawn from this study:  
1. Parametric modeling of curved-tooth cylindrical gears was performed using CREO software, which can realize the rapid construction of the model, improve the modeling efficiency, save time, and reduce the design cost. By analyzing the dynamics of the constructed gears, the contact path of the arc-toothed cylindrical gears in the meshing process is an elliptical region along the middle of the tooth face, which accounts for approximately 50% of the length of the tooth face, and the contact stresses are more uniformly distributed along the contact line. During the gear meshing process, the maximum contact stress occurs at the meshing-in and meshing-out positions, which are 2559.7 MPa and 2225.2 MPa, respectively, and the contact stress at the meshing-in position reaches the maximum value. 2. The design of a tooth profile, combined with the radius of the curved tooth line of the comprehensive trimming program, tooth profile trimming selected Walker trimming program, and the program compared to straight-line trimming transition, is smoother and less likely to lead to a stress concentration phenomenon.