| 摘要 |
PCT No. PCT/AU96/00587 Sec. 371 Date Sep. 1, 1998 Sec. 102(e) Date Sep. 1, 1998 PCT Filed Sep. 19, 1996 PCT Pub. No. WO97/11346 PCT Pub. Date Mar. 27, 1997A wood coring drill bit comprising a hollow tube having an internal bore (103) and an exterior (100) with equally spaced bodies (10) of substantially uniform width extending in a helical manner from a cutting end (10) of said drill bit, said bodies (10) defining equally spaced flutes (15) between the edges of adjacent bodies (10), each body (10) comprising a land (20) upstanding from a relief (21) at the leading edge of the body (10), a respective cutting face (12) and associated lip (25) being formed at the end of each body (10) at said cutting end. The wood coring drill bit is characterized by having three equally spaced bodies (10) and flutes (15) said cutting face (12) has an included angle which is preferably 125 DEG for hardwood and drywood and 112 DEG for softwood. The lip (25) has a lip clearance angle that is about 6 DEG +/-1 DEG , the lands (20) on the bodies (10) extend for an axial distance of about 65 mm+/-5 mm from said cutting end (101) and the internal bore (103) of the hollow tube is tapered outwardly from or adjacent the cutting end (101). |
