Experimental Study On High-speed Wire Tapping And Tapered Edge Passivation

Taps are often used to process the medium and small size screwed holes,especially when the small size screwed holes needed to be machined, taps arenearly the only way to choice, so taps are widely used in production. Duringactual tapping process, with the increase of cutting depth, the cutting part isburied in the workpiece when tapping, that’s to say the multiple bladesparticipating in the process of tapping which does not only lead to the biggertapping torque but also difficult to disperse the cutting heat, so compared withthe single blade cutter, the cutting environment is much harder. After grinded,kinds of micro defects are left on the cutting edges and the grinding traces wereleft on the rake and flank surface. The defects mentioned above will not nolylead to breakage of cutting edge but also accelerate the wear of rake and flanksurface, this reduce the stability of taps and have the tapping durability gotshortened greatly. In the view of this, based on the electrolytic passivation, theM8HSS tap will be passivated, through the experiments between unpassivatedand passivated taps, the effects of cutting edge passivation on tapping processand tapping durability were explored.In this paper, the passivation radius of M8HSS tap used in experiments wascalculated theroretically and determined; the cutting edge was passivated withthe electrolytic passivation equipments; the tapping and durability experimentsbetween passivated and unpassivated taps on H13die steel were implemented.The results of experiments had been disposed, analysed and ended up with theconclusion.The results of tapping experiments showed that the defects on cutting edgeswas removed effectively and the surface quality of rake and flank surface wasimproved by electrolytic passivation; under the optimum passivation radius, thetapping process was stable, the tool wear was reducedand the durability wasimproved, this will have a great effects on improving the production efficiency.This paper had already obtained the support from the national natural sciencefund project“Facing quality integration and the control of high-speed steel tap manufacture&technology research”.The fund number is：51275333.