| 摘要 |
A drill bit for cutting a hole comprising an undercut into a substrate is provided. The drill bit comprises a shaft (10) having a first cutting tip (12), a mandrel (14) on the shaft (10), and a flareable sleeve (16) comprising a second cutting tip (20, 22) drivable separately from the first cutting tip (12). The mandrel (14) and the sleeve (16) are arranged so that urging the sleeve (16) distally over the mandrel (14) flares part of the sleeve (16) outward from the shaft for reaming out the undercut outwardly from the hole. |
