| 摘要 |
PURPOSE:To enable a longer cemented carbide tip to be used for expanding the regrinding range by forming the bottom surface of a spiral groove with a projection protruding radially outward of a thick core portion and extending longitudinally and forming a linear oil path penetrating through the projection and a land. CONSTITUTION:A spiral groove 13 is formed on the bottom surface with a projection 15 protruding radially of a thick core portion 9 and extending longitudinally, and an oil path 21 is formed linearly to extend through the radially inner portion of the projection 15 and a land 11 from a body base 5A to an opening 21A of the end 5B parallel to the axis of a drill 1. Thus, even if the whole body 5 is formed of cemented carbide alloy, the oil path 21 can be formed throughout the whole length of body 5 at the same time as forming the body 5 by utilizing a wire or the like. As a result, the regrinding range of the cemented carbide drill 1 can be ensured over the wide range for the cost reduction.
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