发明授权
US4645389A Multiple-tooth drill bit 失效
多齿钻头

Multiple-tooth drill bit
摘要:
A multiple-toothed drill bit having at least three teeth is provided with front end cutting edges having respective outer and inner cutting edge sections oriented angularly to each other and meeting at respective frontwardmost cutting points located in a common plane, and with an axial centering spur having laterally outwardly and rearwardly inclined center cutting edges merging with the inner front end cutting edge sections via respective frontwardly concave cutting edge sections.
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