Development And Performance Of Monolayer Brazed Multicrystalline CBN Grinding Wheels

Multicrystalline cubic boron nitride (CBN) grains are another artificial material sintered underhigh pressure and high temperature. They could be devided into polycrystalline CBN (PCBN) withbinder and binderless CBN (BCBN) without binder. Multicrystalline CBN grains possess the sameexcellent properties as the CBN grains, i.e. high hardness, superior chemical stability, good thermalinert and grinding performance. Moreover, multicrystalline CBN grains enjoy outstandingself-sharpening performance by virture of the micro-fracture behavior in the grinding process. Thus,the phenomenon that CBN grains could not self-sharpen is avoided.In this paper, the monolayer brazed grinding wheels with multicrystalline CBN grains weredeveloped. The fabrication mechanism and the grinding performance of the wheels were investigated.The results obtained could benefit to the application of the abrasive tools with multicrystalline CBNgrains in the high efficiency and precision grinding process of difficult-to-cut materials, i.e. titaniumalloys, nickel superalloy.The main work is as follows:(1) Brazing experiments of PCBN grains and BCBN grains were carried out using Cu-Sn-Tialloy as the filler, respectively. The influence of brazing temperature and holding time on theinterfacial microstructure and fracture strength of the brazed components were discussed. Theoptimized brazing process was determined as brazing temperature of900℃and holding time of8min.(2) The wear resistance of the brazed multicrystalline CBN grains was tested and evaluated. Thewear characteritics of PCBN grains, BCBN grains and monocrystalline CBN grains was analyzed.The self-sharpening mechanism of the multicrystalline CBN grains was investigated.(3) The monolayer brazed grinding wheels with BCBN grains were designed and fabricated.Comparative study of the grinding performance were conducted between brazed wheels with BCBNgrains and that with monocrystalline CBN grains in the high-speed grinding process of nickelsuperalloy GH4169. The influence of the grinding parameters on the grinding force and temperaturewere studied. Better grinding performance of the brazed wheels with BCBN grains were exhibited.