ENGINEERING FOR BEGINNERS 9

摘要

The mechanical effect that is created by inverting cutting tools is quite simple and can be employed to great effect when parting off or grooving, which we will look at next. To understand this machining situation you must again imagine yourself sitting on the cutter. Due to the machine's construction, any conventional machining pressures are directed downward and resisted by the solid construction of the saddle and bed ways. The effect of this is to put the turning tool under two distinct pressures. Firstly the downward pressure generated by the cutting action between the tool and the material being cut (remember the cutting angle we discussed earlier) and the integral strength of the tool itself, which is trying to resist it. The greater the tool overhangs, the more these conditions are amplified and the tendency of the cutting tip is to dip and dig into the surface of the material, so causing the vibration and rough surface finish.