## 6 Conclusions  
In this paper, aiming at solving the problem of the edge tooth fracture of the bit in the high-strength formation of large-diameter geothermal drilling, the failure mode, failure mechanism, and common solutions of the bit are studied and analyzed. A cluster DTH hammer bit with edge buttons is innovated upon and designed, and the field test application is carried out, which significantly improves the life of the drill bit. The conclusions of this paper are as follows:  
1. The tooth-breaking mechanism of the large-diameter high-strength DTH hammer bit is that the rotation speed to be too high relative to the impact frequency, and the diameter of the spherical buttons is small, resulting in a large distance between the rock mass at the bottom of the hole and a large rock ridge at the bottom of the hole, and the strong shear of the spherical buttons is mainly caused by a high-strength residual rock ridge.
2. The cluster design of the edge buttons of the bit is innovatively proposed to increase the equivalent diameter of the edge buttons and remove the bit restriction that the low shifting rotary speed of the drill is too high. Under the conventional rotation speed, the drilling life of the bit is significantly improved in high-strength formations.
3. The field application shows that the life of the large-diameter drill hammer drill in high-strength formation drilling has been increased from 71-89 m to more than 365 m, which is about four times the life of the original bit, reducing the drilling cost and improving the drilling efficiency.  
We have not yet fully studied the effect of this design on the penetration rate of the bit. After the edge buttons are gathered, the stress will be more concentrated, and the stress generated by the impact of the rock in the multi-tooth fractured rock is higher than that generated by the impact of the bit before the design, which can break rock more quickly and improve the efficiency of rock breaking, but at the same time, the drilling pit will be correspondingly reduced. Next, we will deeply study the relationship between and influence of various factors of the rock breaking of the bit, explore the optimization of the bit under different geological conditions, and design the bit with better economic benefits.  
Figure 7: Application of DTH hammer bit in large-diameter and high-strength formation. (**a**) The previous bit. (**b**) The innovatively designed bit.  
**Author Contributions:** Conceptualization, [PERSON] ([PERSON]), X.Z. and C.B.; methodology, [PERSON] ([PERSON]), X.Z. and C.B.; validation, [PERSON] ([PERSON]), X.Z. and C.B.; formal analysis, S.H., [PERSON] ([PERSON]) and L.T.; investigation, [PERSON] ([PERSON]), S.H. and L.T.; resources, C.B. and X.Z.; data curation, [PERSON] ([PERSON]) and C.B.; writing--original draft preparation, [PERSON] ([PERSON]); writing--review and editing, [PERSON] ([PERSON]), [PERSON] ([PERSON]) and S.H.; visualization, L.T.; supervision, X.Z. and C.B.; project administration, [PERSON] ([PERSON]) and funding acquisition, X.Z. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by Project (2022 XAGG0500) supported by Xiong'an New Area Science and Technology Innovation Special Project of the Ministry of Science and Technology, as well as Project (42172342) supported by the National Natural Science Foundation of China.  
**Data Availability Statement:** Data are contained within the article.  
**Conflicts of Interest:** Author [PERSON] was employed by the company Beijing Taili New Energy Technology Co., Ltd. The remaining authors declare that the re-search was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.