1 • Drilling and Drills 钻 削 和 钻 头 Drilling involves producing through or blind holes in a workpiece by forcing a tool, which rotates around its axis, against the workpiece
钻 削 就 是 通 过 迫 使 绕 自 身 轴 线 旋 转 的 切 削 刀 具 进 入 工 件 而 在 其 上 生 成 通 孔 或 盲 孔
Consequently, the range of cutting from that axis of rotation is equal to the radius of the required hole
In practice, two symmetrical cutting edges that rotate about the same axis are employed
因 此 , 从 旋 转 轴 线 开 始 的 切 削 范 围 等 于 所 需 孔 的 半 径
实 际 上 , 使 用 的 是 两 条 围 绕 相 同 轴 线旋 转 的 对 称 切 削 刃
Drilling operations can be carried out by using either hand drills or drilling machines
The latter differ in size and construction
Nevertheless, the tool always rotates around its axis while the workpiece is kept firmly fixed
This is contrary to drilling on a