Research On Vitrified Bond CBN Tools For Ultra-high Speed Grinding

Ultra-high speed grinding technology is a modern processing technology that can improve the material removal rate, machining precision and machining quality, and now the domestic technology of ultra-high speed grinding lags far behind foreign technology, so the study on ultra-high speed grinding is extremely important.In this paper, vitrified bond for ultra-high speed grinding CBN abrasive tool and CBN abrasive tool formula were studied. Al₂O₃-SiO₂-B₂O₃-R₂O-MO was chosen as the basic vitrified bond system in this study, the effect of different component on the basic vitrified bond performances, influences of Bi₂O₃, Na₃AlF₆ and CaF2 as additives on the basic vitrified bond properties, and the effect of preparation process on vitrified bond performances were studied. Finally, influences of vitrified bond content and molding density of the abrasive tools were also investigated. The results showed that:1) In Al₂O₃-SiO₂-B₂O₃-R₂O-MO vitrified bond system, as the Al₂O₃ content increased, the refractoriness of vitrified bond increased, the fluidity decreased and the bend strength of the samples increased; the refractoriness of vitrified bond decreased with the increasing of the B₂O₃, bend strength of the samples reached the highest value when the content of B₂O₃ was 18.3%; the refractoriness of vitrified bond reached the lowest value when the content of CaO was 1% and bend strength of the samples reached the highest value when the content of CaO was 5%.2) The refractoriness and fluidity of the basic vitrified bond were improved efficiently after the introduction of the Bi₂O₃, while there was no obvious effect on bend strength of the samples. The refractoriness, fluidity and wet-ability of the vitrified bond were improved and the bend strength of the samples increased after the introduction of fluoride. The effect of Na₃AlF₆ on refractoriness, fluidity and wet-ability of the vitrified bond was much more obviously than that of CaF2, but the samples with CaF2 showed better bend strength than that of Na₃AlF₆.3) Pre-melting was efficiency to improve the refractoriness and fluidity of vitrified bond, and bend strength of the samples increased after pre-melting.4) Bend strength and Rockwell hardness of the samples increased with the increasing of vitrified bond content and molding density.