Research On Specialization Of Modfied Tooth Tap's Groove Parameters For Typical Difficult-to-Machine Materials

As the difficult-to-machine materials widely applied in aviation, aerospace, nuclear.etc., problems of tapping become prominent, and taps almost are imported. The special forming principle of modified tooth taps can greatly reduce tapping torque, so they could be used as effective tools of machining difficult-to-machine materials. However, there are too many kinds of difficult-to-machine materials, and they have different characteristic. So tap's groove parameters should be different. In this paper, specialization of tap's parameters for five kinds of typical difficult-to-machine materials (titanium alloy TC4, Austenite stainless steel 1Cr18Ni9Ti, nickel-base high-heat alloy GH4169, high-strength steel F175 and super- strength steel D406A) is studied, which has great practical value.Firstly, based on the reviews of the characteristics and status on tapping difficult-to-machine materials at home and abroad, four basic groove parameters of tap were analyzed in order to enhance the ability of chip removing and prevent from the chip plug when rollback. Then, dedicated design of two grooves for five difficult–to-machine materials were carried out, and contour shape of the second groove processing tools– form cutter and grinding wheel was designed.Secondly, the equivalent simulation model of tapping process is developed by using DEFORM and Third Wave AdvantEdge finite element software. Simulation on the chip curling of tapping TC4 was investigated, and the influence of rake angle and chip flute shape on the chip curling was analyzed.Finally, manual and automotive tapping experiments on the five kinds of difficult-to-machine materials were carried out by using the two kinds of designed groove modified tooth gap. The tapping torque and tapping temperature was also recorded. According to the contrasted results of the two kinds of groove gapping, the simulation validity is proved. By means of choosing geometry angle of gap which is used for the five kinds of typical difficult-to-machine materials, the gap's specialization is realized.Result indicated that the two kinds of designed groove modified tooth gap could directly resolve the tapping problems of the five kinds of typical difficult-to-machine materials.