Issued Patents 2017
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 9828806 | Roller bit for rock breaking by rotary cutting | Liang Zhang, Shu Li, Defa Zeng | 2017-11-28 |
| 9562398 | Modular cutting-teeth drill bit with controllable drilling specific pressure | Liang Zhang, Shu Li, Defa Zeng | 2017-02-07 |