Method for Processing Deep Hole
1) To reaming hole with twist-drill,in order to reduce the cutting force when machine big hole ,for the hole with diameter ¢50～¢70mm,we drill the hole with drill of diameter ¢25～¢40mm firstly,and then reaming it with bigger-diameter drill,however ,this way is only available for the hole without high precision requirement.If the hole with high precision requirement at H7,and surface roughness at Ra3.2um ,we can achieve it by rough-drill ,semi-finish drill and then finish drill ,however ,for the finish-drill we have to select the one with good flute without any defectiveness ,meanwhile to grind the cutting edge angle at 3º～5º ,with which the flute connect is ground into comparatively sharp radius , In processing ,the cutting speed at low as Vc＜10m/min,take lubricant with good performance ,so as to avoid chip-accumulation tumor.
2) Symmetrical double-flute floating reaming, this cutting tool has been used for roughly reaming deep hole without any vibration owing to the support of bearing sleeve. The hole could be enlarged by 30~80mm by one process and do not need retract the cutting tool to remove the chip. This cutting tool with simple installation tools, even though take high speed steel as material and cutting speed only at around Vc=20m/min,its cutting depth very deep ,also its reaming working efficiency is very high .On the other hand ,since it is symmetrical double-flute floating cutting ,so can achieve the balance of two flute’s cutting force This tools have been used in turning latches for reaming .Its bearing sleeve material is cast iron,in addition its outer diameter d is smaller at 0.2~0.5mm than the previous machined hole diameter,in the meantime ,its inner hole and shank can be matched and available to rotate .
