## 3 Results and Analysis
### Temperature Rise and Thermal Deformation Patterns of DPRS  
#### 3.1.1 Influence of Ambient Temperature  
Figure 9 shows the temperature variation at each of the main temperature nodes at ambient temperatures of 20 and 130 \({}^{\circ}\)C for an initial temperature of 20 \({}^{\circ}\)C, an axial load of 30 kN, and a speed of 3000 rpm. The temperature rise trend of the temperature nodes is similar at different ambient temperatures: the temperatures of the nodes all increase over time and eventually converge to a steady state, and the steady-state temperature of each part increases as the ambient temperature increases. An analysis of the steady-state temperatures of the nodes at different ambient temperatures shows that Node #27 on the roller column has the highest temperature, and Node #22 has a much lower temperature than that of #27. This is because Node #27 is at the heat source and has a low heat transfer. Nodes #38 and #33 are temperature nodes on the screw, and the temperature of Node #38 is higher than that of Node #33 because of the proximity of #38 to the heat source and the absence of convective heat exchange with the air. Nodes #9 and #10 on the nut have the lowest temperatures because the nut has the largest contact area with the outside environment and the strongest convective heat exchange with the air. Figure 10 illustrates the axial thermal deformation of the DPRS at different temperatures. It is evident that the axial thermal deformation of the DPRS becomes greater with increasing ambient temperature. At various ambient temperatures, the DPRS roller deformation is the largest, followed by the screw deformation, and the nut deformation is the smallest because of differences in the steady-state temperatures of the components.  
The results show that the temperature of each part of the DPRS at different ambient temperatures reaches a steady state after a period of operation, and that the steady-state temperature of each part is influenced by the ambient temperature. The steady-state temperature of the roller is higher than the temperature of the screw, and both parts have uneven temperature distributions. The nut temperature is the lowest. The magnitude of the thermal deformation of each part at different temperatures is consistent with the temperature differences between the parts.  
In [13], [PERSON] et al. obtained similar screw temperature rise curves using numerical calculations and experimental methods. Under the conditions of 8 kN and 180 rpm, the screw temperature increased from room temperature of 25 \({}^{\circ}\)C to 45 \({}^{\circ}\)C within 2000 s. These results closely resemble the numerical calculations presented in this section, providing validation for the accuracy of the computations.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Thread** & **Number of** & **Screw Pitch** & **Roller Pitch** & **Roller Pitch** & **Nut Pitch** \\
**Pitch** & **Screw Heads** & **Diameter** & **Diameter** & **Diameter** & **Diameter** \\
**\(P_{0}\)/mm** & **\(n_{\text{s}}\)** & **\(d_{\text{s}}\)/mm** & **(major)** & **(minor)** & **\(d_{\text{N}}\)/mm** \\ \hline \(1\) & \(1\) & \(8.9\) & \(5.9\) & \(4.7\) & \(19.5\) \\ \hline \hline \end{tabular}
\end{table}
Table 2: Structural parameters of a DPRS product.