Lapping Technology Of Pcbn Circular Cutting Tool

Binderless PCBN is a new type of super-hard material.Compared with the ordinary PCBN,it has high hardness,good toughness,high temperature resistance and other excellent properties,it is a fine tool material for precision and ultra-precision processing of iron-based materials.At present,due to the influence of binder,commercial PCBN tools have a large blunt radius of the cutting edge,which is difficult to be used in ultra-precision machining.In addition,mechanical grinding is a widely used machining method in the manufacture of super-hard cutting tools.It has the advantages of simple machining equipment,easy operation,high precision and high efficiency.Therefore,this paper intends to adopt the new super-hard PCBN block material to study the mechanical lapping technology of arc edge tool applied in ultra-precision cutting.In this paper,the excellent properties of PCBN tool material and the preparation method of super-hard tool were analyzed.The material removal mechanism of binderless PCBN in mechanical lapping process was analyzed with the brittle plastic transformation and the theory of mechanics.The results provides the theoretical basis for the lapping process of the cutting tool.Then,based on the available lapping machine,the auxiliary device was designed for lapping rake face and flank surface of the cutting tool,and the dressing device of lapping disc was further improved.On the basis of setting up the experimental platform,the mechanical lapping parameters of rake face and flank surface are optimized by orthogonal experiment.The influences of lapping disc speed,pressure and size of abrasive grains on the lapped surface morphology and removal efficiency of the material were analyzed.Finally,the tool handle was welded with the PCBN bulk,and then the preparation experiment of binderless PCBN tool was completed according to the optimized mechanical lapping parameters.The formation process of cutting edge was analyzed and then the roundness of cutting edge reached 389 nm.The ultra-smooth rake face and flank surface was obtained with surface roughness Ra of 0.643 nm and 6.54 nm respectively.