| 摘要 |
A chip breaker drill bushing assembly (11) for a fluted drill bit (37) is disclosed. The assembly comprises a drill bushing housing (13) and a sleeve (15). The drill busing housing (13) includes a body (17) and an outwardly protruding guide shaft (19). The guide shaft has a smooth end (31) for tightly contacting the surface of a work piece (63) to be drilled. The sleeve (15) is located in the body (17) of the housing (13), in alignment with the guide shaft. The end of the sleeve (15) facing the tip (29) of the guide shaft (19) includes a chip breaker (41). The chip breaker (41) includes two spaced-apart teeth (46a, 46b) that are defined by two helical troughs (47a, 47b) that protrude into the sleeve (15). The two helical troughs (47a, 47b) are aligned with two longitudinal apertures (33) in the outwardly protruding guide shaft (19).
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