Study On The Glass-ceramic Bond Of CBN Grinding Wheel

Cubic boron nitride?cBN?grinding wheel has been widely used in grinding iron casting materials,high speed steel and tool steel materials for its advantages such as high grinding efficiency,long service life,good surface quality of grinding workpiece and non-ferrous properities.In this paper,the properties of glass-ceramic bond for cBN grinding wheel are studied systematically,and the grinding properties of cBN grinding wheel with glass-ceramic bond is tested.The sintering temperature and high temperature fluidity of glass-ceramic bond were tested by shrinkage rate and plane flow method respectively;the three-point bending strength of glass-ceramic bond specimens were tested by DZS-II assembly-type material surface and interface performance tester;PCY-?thermal expansion coefficient tester was used to test the thermal expansion codfficient of glass-ceramic bond specimen in 20-500?and the D/max-rB rotary anode X-ray diffractometer and the Hitachi S-4800II scanning electron microscope were used to analyze the phases and morphology of the samples.Results show that the introduction of alkaline earth oxides?MgO,CaO,SrO,BaO?into the Li₂O-ZnO-Al₂O₃-SiO₂ glass-ceramic bond system can increased the fluidity of the bond in high temperature,reduced the thermal expansion coefficient of the bond,improved the combination between cBN abrasives and glass-ceramic bond,so that cBN abrasives specimens bending strength from 84.2 MPa to reached 109.3 MPa.By introduced BaO/SrO?N?with different molar ratios into the bond,the mechanical properties such as flexural strength and microhardness of glass-ceramic bond can be adjusted;and the samples bending strength of containd cBN abrasives reached 154.4 MPa when N=5.When Na₃AlF₆ were introduced into the bond,the sintering temperature of glass-ceramic bond can be reduced obviously and the pores on the bond bridge among cBN abrasives were removed so that the boning state between bond and cBN abrasives were improved.The prepared glass-ceramic bond and cBN abrasive are prepared into the grinding wheel for the grinding of 45^#steel,the grinding wheel speed is 25 m/s,30 m/s and 35 m/s respectively,and the lateral feed of the grinding wheel is 3?m,5?m,7?m and 9?m.With the glass-ceramic bond and cBN abrasive were prepared into the grinding wheel for practical grinding,the grinding results show that the roughness of workpiece surface decreased with the increase of grinding wheel speed when the cut depth of grinding wheel was constant.And the roughness of workpiece surface increased with the increase of the grinding wheel cut depth when the grinding wheel speed was constant.When the wheel speed is 35 m/s and cut depth is 3?m,the roughness of workpiece surface reached 0.42?m.