# The Impact of Drilling Parameters on Drilling Temperature in High-Strength Steel Thin-Walled Parts
## 4 Effect of Drilling Dosage on the Temperature During Thin-Wall Drilling
### Influence Law of Feed Volume on the Bottom Surface Temperature of Thin-Wall Drilling Process  
At the rotational speed \(n\) = 750 r/min, the effect of feed rate on the maximum temperature of the bottom surface of the workpiece was investigated by changing the feed rate (\(f\) = 0.01 mm/r, \(f\) = 0.025 mm/r, \(f\) = 0.05 mm/r, \(f\) = 0.075 mm/r, \(f\) = 0.1 mm/r), and the temperature field of the bottom surface of the workpiece was investigated by changing the feed rates (\(f\) = 0.01 mm/r, \(f\) = 0.025 mm/r, \(f\) = 0.05 mm/r, \(f\) = 0.075 mm/r, \(f\) = 0.1 mm/r). T\({}_{\rm max}\) is shown at different characteristic positions in Figures 3 and 4. Regarding the location where the maximum axial force is generated, it can be seen from Figure 11 that when \(f\) = 0.01\(\sim\)0.1 mm/r, the moment when \(F_{\rm max}\) appears is generally delayed compared to point C\({}^{\prime}\), with only one exception: when \(f\) = 0.025 mm/r, the F\({}_{\rm max}\) point precedes point C\({}^{\prime}\). As shown in Figure 7 and related analysis, when \(v_{\rm c}\) = 18.84 m/min (\(n\) = 750 r/min) and \(f\) = 0.025 mm/r, the cutting temperature is relatively low, the softening degree of the workpiece cutting area is small, and the thickness of the yielding and outward deformation at the hole edge is small. The maximum cutting force occurs when the primary cutting edge is completely drilled into the workpiece, and the chisel edge has not yet exited the bottom surface. When \(f\) \(\geq\) 0.05 mm/r, the reason why the F\({}_{\rm max}\) point is delayed compared to point C\({}^{\prime}\) is that the yielding and outward deformation of the hole edge when the intersection of the primary and secondary cutting edges is about to exit the bottom surface of the workpiece results in an axial force which is greater than that when the primary cutting edge is completely drilled into the workpiece. When \(f\) = 0.01 mm/r, the main reason why the F\({}_{\rm max}\) point is delayed compared to point C\({}^{\prime}\) is that due to the existence of the cutting edge radius, the primary cutting edge of the drill bit is limited by the minimum cutting thickness when \(f\) = 0.01 mm/r. The compression effect on the workpiece is greater, generating more frictional heat, which softens the material in the cutting area and causes yielding and outward deformation of the hole edge when the intersection of the primary and secondary cutting edges is about to exit the bottom surface of the workpiece. Figure 12 shows the variation in the maximum temperature of the bottom surface of the workpiece in accordance with feed rate, specifically when the drill bit is at the four characteristic positions of A\({}^{\prime}\), C\({}^{\prime}\), F\({}_{\rm max}\), and T\({}_{\rm max}\) under different feed conditions. It can be seen that, overall, the maximum temperature of the bottom surface of the workpiece increases with the increase in feed rate when the drill bit is at different characteristic positions, but this increase is less pronounced than the increase caused by cutting speed. When \(f\) = 0.1 mm/r, the temperatures at points A\({}^{\prime}\) and C\({}^{\prime}\) are slightly lower than those at \(f\) = 0.075 mm/r. This is mainly because with a larger feed rate, the chips are larger and carry away more heat. Figure 10: The effect of spindle speed on the rate of increase in the maximum temperature of the bottom surface of the workpiece. Figure 11: Variation in the temperature field on the bottom surface of the workpiece under different feed rates. From the change in the maximum temperature of the bottom surface of the workpiece in the drilling process, the influence of the feed volume on the maximum temperature of the bottom surface of the workpiece in the drilling process is not significant; moreover, the maximum temperature of the bottom surface of the workpiece in the drilling process increases from 327.8 \({}^{\circ}\)C to 365.6 \({}^{\circ}\)C when the feed volume increases from 0.01 mm/r to 0.1 mm/r.