Study On Grinding Performance Of Vitrified Bond Diamond/CBN Grinding Wheels

Vitrified bond diamond / cubic boron nitride(CBN)grinding wheels have the advantages high grinding efficiency,long service life and high machining accuracy,etc.,are widely used in the field of precision machining.According to the previous resesrch results,using boroaluminosilicate glass as the base vitrified bond,the experiment studies the effect of sintering temperature on performance of vitrified bond diamond grinding wheel;the effect of amount of walnut shell powder and elemental Sn on the mineral composition,physical properties,microstructure and vitrified bond CBN internal grinding wheel grinding 45 steel,and the influence of grinding parameters and changes of three major components of the inner grinding wheel on the grinding performance.Meanwhile,this experient uses X-ray diffraction(XRD),thermal analysis(TG-DSC),planar flow method,Archimedes drainage method,and scanning electron microscope(SEM)etc.,to characterize physical properties of the phase composition,abrasive loss,fluidity,open porosity,bending strength,microstructure of samples.The grinding experiment uses the grinding wheel grinding power and the wear ratio to characterize the grinding performance of the grinding wheel.The research work draws the following conclusions:(1)In the study,as vitrified bond diamond grinding wheel sample is sintered,with the tenperature increasing,the fluidity of vitrified bond adds,and open porosity of vitrified bond diamond wheels samples increases;as the sintering temperature is 700 ℃,the bending strength of samples(84.11 MPa)and the Rockwell hardness(87.66 HRB)reach the maximum valuse,the vitrified bond “bridge” between diamonds is denser,and the wetting property between vitrified bond and diamond is better,forming a whole with suitable pores.(2)Adding 1 wt.% of elemental Sn to the CBN grinding wheel samples,the flow of vitrified bond reaches maximum(149%),open porosity reaches minmum(13.13%),and the bending strength reaches 59.87 MPa;XRD characterizes cassiterite crystal in the vitrified bond;By SEM,adding 1 wt.% of elemental Sn,fluidity of vitrified bond is good,wettability of vitrified bond to CBN abrasive is good,the structure is dense,and pores are relatively small.(3)Throgh orthogonal experimental analysis,the order of infulence of grinding parameters on grinding performance is as follows: grinding wheel speed > horizontal feed rate > the grinding amount;optimal grinding parameter: grinding wheel speed is18000 r/min,horizontal feed rate is 2 μm,and grinding amount is 0.1mm.As the volume fraction of vitrified bond of grinding wheel increases,the grinding powder of grinding wheel increase;as the volume fraction of the porosity of grinding wheel increases,the grinding powder of grinding wheel decrease.(4)The content of walnut shell powder increased from 0 wt.% to 8 wt.%,the grinding power of CBN grinding wheel decreased,and the wear ratio increased.Adding the mass fraction adds 8% walnut shell powder to vitrified bond CBN grinding wheels,grinding powder of vitrified bond CBN grinding wheel reaches minmum value(1197 W)and wear ratio reaches maximum value(584)and grinding wheel has the best performance.The addition of elemental Sn content increases from 0 wt.% to 4 wt.%.The grinding power of CBN grinding wheel increases first and then decreases,and the wear ratio increases and then stabilizes.As adding 4 wt.% of elemental Sn,grinding powder and wear ratio of grinding wheels are 2385 W and 685 respectively,and grinding wheel has good grinding performance.