# The Impact of Drilling Parameters on Drilling Temperature in High-Strength Steel Thin-Walled Parts
## 2 Experimental Condition
### Experimental Programme  
Firstly, the bottom surface temperature field variation during the drilling of thin-walled parts of high-strength steel was investigated by fixing the cutting dosage; furthermore, the influence of the drilling dosage on drilling temperature was investigated using a one-way experimental method, and the parameters of spindle speed and feed were selected as shown in Table 3. All tests were conducted under dry-drilling conditions without coolant or lubricant. The workpiece was clamped along two opposite edges. The drill used was a SANDVIK carbide-coated drill, with a diameter of \(\Phi\)8 mm, and an apex angle of 140\({}^{\circ}\). The diameter of the top edge of the drill was about 3.2 mm, and the height of the tip of the drill was 1.4 mm. The structure of the drill is shown in Figure 2.  
Figure 1: AF1410 steel thin-wall drilling temperature test system. Figure 2: Drill bit photos. Variation in the Temperature Field on the Bottom Surface of the Workpiece During the Drilling of Thin-Walled Workpieces  
Correlation Between Axial Force and Maximum Bottom-Surface Temperature of the Workpiece During Thin-Wall Drilling  
Drilling experiments were carried out on AF1410 thin-walled workpieces under the conditions of spindle speed \(n\) = 1250 r/min (cutting speed \(v_{\text{c}}\) = 31.4 m/min) and feed \(f\) = 0.025 mm/r. The change curves of axial force and maximum temperature of the bottom surface in the drilling process with the drilling time are shown in Figure 3, and the comparison of theoretical and actual characteristic positions of the tool and the workpieces in the drilling process are shown in Figure 4. The comparison of theoretical and actual feature point positions of the tool and workpiece during the drilling process is shown in Figure 4.  
In Figure 3, the vertical black dashed lines represent the theoretical positions (moments) of the drill bit and the workpiece characteristic points without considering workpiece deformation. The multiple vertical black lines in Figure 3, from left to right, correspond to the following positions in Figure 4a: the chisel edge of the drill bit just begins to contact  
Figure 4: Schematic diagram of the characteristic stages of drilling thin-walled plates of high-strength steel. \begin{table}
\begin{tabular}{c c} \hline
**Drilling Volume** & **Numerical Value** \\ \hline Feed rate (mm/r) & 0.01, 0.025, 0.05, 0.075, 0.1 \\ Spindle speed (r/min) & 500/12.6, 750/18.8, 1000/25.1 \\ /Cutting speed (m/min) & 1250/31.4, 1500/37.7 \\ \hline \end{tabular}
\end{table} 
Table 3: Experimental plan. Figure 3: Variation curve of axial force and maximum surface temperature of the workpiece drilled (\(n\) = 1250 r/min, \(v_{\text{c}}\) = 31.4 m/min, \(f\) = 0.025 mm/r). the upper surface of the workpiece (Position A), the intersection of the drill bit's primary and secondary cutting edges reaches the upper surface of the workpiece (Position B), the chisel edge of the drill bit reaches the bottom surface of the workpiece (Position C), the intersection of the drill bit's primary and secondary cutting edges reaches the bottom surface of the workpiece (Position D), and the drill bit completely exits the bottom surface of the workpiece (Position E). Theoretically, there are two situations that could occur: the axial force is at its maximum and remains relatively stable when the drill tip has completely entered the upper surface of the workpiece but has not yet exited the bottom surface; the axial force will become 0 when the intersection of the drill bit's primary and secondary cutting edges reaches the bottom surface of the workpiece. From Figure 3, it can be seen that the axial force and the maximum temperature of the bottom surface of the workpiece change curve; moreover, the maximum temperature of the bottom surface of the workpiece increases to nearly linear growth to the maximum temperature and begins to show a downward trend.