Experimental Study On Wear Morphology Of Mental Glass(Vit1)cutting Tool

Zr-based metallic glasses due to the microscopic atomic arrangement of long-range disorder and short-range order characteristics,the macroscopic structure shows high strength,high hardness,high toughness,low thermal expansion coefficient and density of excellent mechanical and physicochemical properties in the field of industrial and civil defense widely used.The high hardness,low elastic modulus and low thermal conductivity of Zr-based metal glass make it a typical difficult to machine material.It is found from the existing cutting experiments that the tool wear is serious and the machining cost is high.As a new type of engineering material,there are no systematic reports on the wear and tear of metal glass in the existing literature.In this paper,Vit1 type bulk metallic glass(Zr41.2Ti13.8Cu12.5Ni10.0Be22.5)as the processing object and selects the experimental machining of hard alloy and PCBN tools,two kinds of tool wear morphology of the system and try to explore the mechanism,so as to provide experimental reference for enterprises of metallic glass cutting tool selection and tool design etc.The material properties of the test design for Vit1 type metallic glass,the principle and tool manufacturers advice tool selection with the common hard brittle materials processing,the company selected CVD double coated cemented carbide tool(model: SNMA 120408 TK2001)and uncoated PCBN tool(model: SNGA120408S-02020-L1-D CBN200).The temperature sensitive characteristic experiment of the bar and the objective conditions the number and size of the bar,by the method of single factor experiment: change the cutting speed,cutting depth of ap=0.2mm VF =0.1 mm/r;feed rate;cutting speed were v1=0.52 m/s,v2=0.3 m/s,v3=0.2 m/s.By means of laser scanning confocal microscope and scanning electron microscope(SEM),the tool wear morphology of cemented carbide cutting tool for cutting Vit1 metal glass was observed and analyzed by back scattering imaging and EDS energy spectrum analysis.The observation results showed that tool wear form before the main crater wear,flank wear and spalling wear built-up edge;flank wear morphology mainly for coating delamination wear and crack;cutting edge region due to the chip attached to determine whether the occurrence of micro chipping wear.In addition,with the decrease of cutting speed,the length of wear area increases obviously,which is an obvious feature of wear.With the tool wear form,cutting force and tool time domain analysis of acoustic emission signals,found that the cutting process of mechanical impact of severe wear;through the analysis before and after the flank wear morphology and EDS spectrum results,found the knife before and after bonding wear exists in the face of the tool,and oxidation wear mainly exists in the rake face of the tool wear;the regional longitudinal sections of the back scattering imaging and EDS spectrum analysis showed that the diffusion wear of the cutting tool,workpiece elements to the diffusion depth of tool material is about 2.2?m.The main wear and failure morphoiogical of the PCBN tool are the tool edge collapse,the cutting of the cutting tool material,the chip and micro chipping of the main cutting edge.There is a high negative correlation between the wear degree of PCBN tool and cutting speed,that is,with the cutting speed decreasing,the tool wear is more severe.PCBN cutting tool wear is mainly due to the material properties of Vit1 metallic glass rod material in cutting system produced severe vibration through the analysis of cutting force and tool of the acoustic emission signal data,vibration and impact point and the tool rake face severe damage.Finally,the XRD structure of the machined surface of the cutting rod was tested.It was found that the surface is still amorphous and the crystallization phenomenon has not occurred because of turning.