要在管壁上精确地钻削出偏置孔是很困难的,即使采用标准的两刃立铣刀,也会产生偏斜和错位,形成表面光洁度差的椭圆形孔。但如将立铣刀修磨成图示的阶梯形,就可以避免孔的位置偏差,保证加工孔的尺寸/位置精度、圆度和表面光洁度,并省去了镗/铰加工。 It is difficult to accurately drill offset holes in the pipe wall. Even with a standard two-edged end mill, skew and misalignment can result in elliptical holes with poor surface finish. However, if the end mill is sharpened into a stepped profile, the position deviation of the holes can be avoided, the dimensional / position accuracy, roundness and surface finish of the machined hole can be avoided and the boring / reaming can be omitted.