深穴加工における穴の曲がり : 切れ刃形状の影響

概要

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The influence of the shape of the cutting edge on hole deviation is investigated, using four types of gundrills and a long twist drill. Three of the gundrills have different outer cutting angles. With them, hole deviation becomes larger when the outer cutting angle is bigger than the inner one, i.e. when the total radial force on a cutting edge becomes larger. If the former equals the latter, it becomes less. But an oversized hole is made due to the instability of the tool head. If the convex part is built on the rake face of a gundrill, it restricts the radial movement of the tool. As a result, the hole deviation becomes less and the hole accuracies improve. Hole accuracies in the twist drill are about 10 times worse than the single-edge gundrills, because the tool is liable to bend due to the cutting forces.
社団法人日本機械学会の論文
1988-06-25