Self-Sharpening Characteristic of Novel Spiral Groove Cutter of TBM

Tunnel boring machines (TBMs) are large-scale mechanical devices that play an essential role in the construction of various underground infrastructures, including transportation tunnels, water conservancy projects and hydropower facilities. TBMs are engineered to efficiently excavate through a variety of geological conditions, making them indispensable in modern civil engineering and construction projects. One of the critical components of a TBM is the disc cutter, which is responsible for the rock-cutting process. The performance and longevity of cutters are vital for the overall efficiency of the TBM, as they directly influence the rate of excavation and the quality of the tunnel being constructed. However, the working conditions that disc cutters face are incredibly harsh. As cutters interact with the rock, they experience significant wear due to the nature of the material. This wear leads to a rapid deterioration of the cutter's edges, resulting in a high wear rate that can severely limit the cutter's effectiveness over time. As the cutters become blunt, their ability to break rock diminishes, leading to increased cutting forces, higher energy consumption and ultimately reduce operational efficiency. This phenomenon of wear-induced bluntness represents a significant bottleneck in the performance of TBMs, as it can lead to increased downtime for maintenance and replacement of cutters, as well as higher operational costs. In response to these challenges, this study explored the innovative design of a new sprial groove cutter that incorporated self-sharpening properties based on surface structure engineering. This study aimed to evaluate the change in performance of this sprial groove cutter design before and after wear. Field tests were conducted to collect real wear patterns of the helical fluted cutter and verify its self-sharpening capability. By analyzing the change in rock-cutting performance before and after wear, it was possible to gain insight into the change in milling cutter performance due to self-sharpening and compared it to the change in performance before and after wear of a conventional flat-top cutter. The findings revealled a significant contrast in the wear performance between the spiral groove cutter and the traditional flat-top cutter. Specifically, the results indicated that as the spiral groove cutter underwent wear, its rock-cutting performance improved, which was counterintuitive compared to the performance of the flat-top cutter. For a given depth of penetration into the rock, the worn spiral groove cutter required a reduced load and exhibited lower specific energy consumption. This improvement could be attributed to the self-sharpening nature of the spiral groove cutter, where the average contact area between it and the rock continued to decrease during the wear process, allowing the spiral groove cutter to penetrate deeper into the rock formation more effectively. Conversely, the flat-top cutter experienced an increase in the contact area as it wore down, leading to an escalation in both the cutting force and specific energy. This increase in resistance significantly hampered the rock-cutting performance, illustrating the detrimental effects of bluntness. The study suggested that the self-sharpening features of the spiral groove cutter could offer a viable solution to enhance the performance and longevity of TBM disc cutters. The research on the self-sharpening capabilities of the new spiral groove cutter provided valuable insights that could inform the design and selection processes for cutting tools used in tunnel boring machines. By understanding the mechanisms behind wear and performance enhancement, engineers could develop more effective cutting tools that not only improve excavation rates, but also reduce operational costs and downtime associated with cutter replacement.