加工铝活塞零件用的５ｍｍ螺旋铰刀图１为活塞零件（用ＺＬ１０８铝合金制造）车端面钻铰孔的有关尺寸。原先车端面钻铰孔的工序是：（１）车端面保证总长８４．５ｍｍ，表面粗糙度Ｒａ１．６μｍ。（２）用２．５ｍｍ钻头钻中心孔，深至锥孔口处，表面粗糙度Ｒａ为６．３... 5mm helical reamer for machining aluminum piston parts Figure 1 shows the dimensions of the drilled reaming holes for the piston part (made of ZL108 aluminum alloy). The original car face drilling reaming process is: (1) car end face to ensure a total length of 84.5mm, surface roughness Ra1.6μm. (2) Drill the center hole with a 2.5mm drill, deep into the taper hole mouth, the surface roughness Ra is 6.3 ...