Research On The Influence Of Edge Preparation To The Cutting Performance Of PCBN Tools

The PCBN tool, with many advantages such as high strength, good wear resistance, chemical stability, etc, can effectively solve the difficult machining problem of chilled cast iron and nickel-base superalloy materials. Since PCBN belongs to brittle tool materials, there are different levels of micro-gaps on the grinded cutting edge of PCBN tool, even after carefully grinding, and these micro-gaps are extremely easy to expand in the cutting process, which accelerate the tool wear. If the work-piece material is not uniform or its surface is discontinuous, these micro-gaps will lead the cutting edge's impact resistance to decline, and early breakage occurs. In order to solve the problems above, domestic and foreign scholars have done a lot of studies on geometric parameters, tool structures, cutting parameters, etc, and gained important success, but little information is available about edge prepararion, therefore, it is necessary to research the influence of edge preparation to the cutting performance of PCBN tool. This article carries on the edge preparation to the PCBN tool with abrasive nylon brush, furthermore studies its influence to cutting force, tool life and tool wear by interrupted cutting austempering ductile iron (ADI)and continuous cutting GH4169 nickel-base superalloy.Firstly, the test results of interrupted cutting ADI by using the PCBN tool with different edge radius indicate that along with the increasing of edge radius, the quasi-static force and interrupted impulse force decrease after increasing first, but the radial impact force decreases earlier and increases later; the edge preparation can shorten or even eliminate the initiative wearing stage, improve the tool's impact resistance, reduce the occurrence of chipping or dilapidation, and extend the tool life; under the experiment conditions, the tool life increases first and decreases subsequently as the edge radius increases, the tool with edge radius of 4.8μm has the longest service life, which is three times of that unpassivated; the main wear reasons of tool are abrasive wear and adhesion-diffusion wear. Secondly, the results of continuous cutting GH4169 demonstrate that the cutting force basically assumes increasing trend with the edge radius's increasing, but the cutting force of the tool with edge radius of 4.8μm appears reducing, the tool abrasion is relatively small; the dominant wear patterns are crater wear and groove wear. Besides, the relationship between cutting parameters and cutting forces of the PCBN tools with different edge radius is probed into in the above mentioned experiments.