## 4 Analysis of Calculation Results  
### Rock-Breaking Load of Arcing-Blade Cutters  
In the cutting process, the cutter is primarily subject to three loads, as indicated in Figure 6. These loads consist of the vertical force (\(F_{\mathrm{V}}\)), rolling force (\(F_{\mathrm{R}}\)), and lateral force (\(F_{\mathrm{L}}\)). The vertical force (\(F_{\mathrm{V}}\)) is applied in the normal direction of the cutter, while the rolling force (\(F_{\mathrm{R}}\)) is directed tangentially to the cutter ring. The lateral force (\(F_{\mathrm{L}}\)) is applied in the direction of the cutter shaft. The dynamic rock-breaking load under the working conditions of 2 mm penetration and 80 mm cutter spacing was taken as an example to study the dynamic process of the rock-breaking load of two cutters cutting in sequence. As observed from Figure 7, at the beginning of the cutting stage, the rock-breaking loads of cutter 1 and cutter 2 first increased from 0 to a certain value. Subsequently, the rock-breaking loads exhibited a certain degree of volatility. Comparisons of the three rock-breaking loads reveal that the \(F_{\mathrm{V}}\) was the largest and the \(F_{\mathrm{L}}\) was the smallest, which fluctuated around 0. Figure 5: Dimensions of the arcing-blade cutter. Figure 6: Three-way loads on the cutters. rock-breaking loads for cutter 1 and cutter 2 were almost identical, and varied only at the start and end time. The data represented in Figure 8 depict the average values of the three-directional loads applied to cutter 2 at various penetrations and cutter spacings. At a penetration of 2 mm, the three-directional loads exhibited minimal variation with an increase in the cutter spacing. Specifically, the \(F_{\text{V}}\) remained nearly constant at around 40 kN, the \(F_{\text{R}}\) remained steady at approximately 4 kN, and the \(F_{\text{L}}\) essentially stayed at about 0. It can be observed that the three-directional loads did not change significantly with an increase in the cutter spacing at such a low penetration. Upon increasing the penetration to 4 mm, the \(F_{\text{V}}\) and \(F_{\text{R}}\) initially displayed an upward trend as the cutter spacing increased, followed by a subsequent decline and eventual stabilization. To elaborate, the \(F_{\text{V}}\) increased from 80.5 kN to 105.5 kN as the cutter spacing grew from 40 mm to 60 mm, after which, it remained stable around 105 kN as the cutter spacing extended to 80 mm. Conversely, the \(F_{\text{L}}\) demonstrated an inverse pattern to the \(F_{\text{V}}\) and \(F_{\text{R}}\), as it decreased from 1.7 kN to 0.7 kN with a rise in the cutter spacing from 40 mm to 60 mm, ultimately plateauing near 0 kN with further increases in the cutter spacing. Similarly, at a penetration of 6 mm, the trend of the three-directional loads with an increase in cutter spacing was similar to that observed for 4 mm penetration. It should be pointed out that the three-directional loads at a penetration of 6 mm began to be stable as the cutter spacing reached 70 mm, which is different from the situation for 4 mm penetration. Moreover, for a given cutter spacing, the change trend of the three-directional loads showed an increase with a rise in penetration. For instance, at a cutter spacing of 60 mm, the \(F_{\text{V}}\) increased from 38.4 kN to 141.7 kN and the \(F_{\text{R}}\) increased from 4.3 kN to 15.9 kN as the penetration expanded from 2 mm to 6 mm. In summary, the rock-breaking loads of the arcing-blade cutter did not change significantly as the cutter spacing increased at a penetration of 2 mm. However, when the penetration was 4 mm or 6 mm, the three-directional loads were significantly affected by an increase in the cutter spacing. This change trend is attributed to the synergistic effect between cutter 1 and cutter 2. Cutter 1 initiated the rock-cutting process before cutter 2, then cutter 2 cut the rock under a given cutter space.