| Diamond tools have been extensively utilized in grinding hard-brittle materials,such as stone, cemented carbides and ceramics, because of diamond’s excellentperformances, including high hardness and excellent abrasion resistance. While thebinding agent lacks effective holding strength in particles, the particles of theelectroplating and sintering diamond tools are easy to shed off. All these lead to thetools’ early failure and fail to give full play to the advantages of the diamond. As aresult of the metallurgical bonding of the diamond and the brazing filler metal, thesoldering diamond tools greatly improves the holding strength of the particles andbecomes an important direction for developing a new generation of high-performancediamond tools. Previous researches on the soldering diamond tools are mainlyconcerned with the coarse-grained diamond tools, which aims to efficiently processstone and other hard and brittle materials. In recent years, with soldering diamondtools’ promotion in the fields of hard and brittle materials and half-precise and precisegrinding processing, fine-grained diamond soldering and its application areincreasingly becoming the focus of the study at home and abroad.Based on solving the problems when the fine-grained diamond is soldering, such asthe layer’s uneven thickness, unevenly distributed heating temperatures, and thesolder’s floating, this article adopts the high-frequency induction to make the grindingwheel of the fine-grinded soldering diamond with Ni-Gr alloy as the solder, andfurther improves the grins’ contours of the wheel surface through modifyingprocedures, and finally evaluates the characteristics of the wheel’s grinding force andthe surface’s quality by means of grinding three kinds of hard and brittle materials,which are yttrium vanadate crystal, alumina ceramics and Mongolia black granite.Accordingly, the main contents of this study are as follows:1. In order to get an even brazing alloy layer, a coating device is designed. In orderto reduce the uneven degree of temperature distribution of steel matrix inhigh-frequency induction heating, a rotating brazing device is designed. And then thefluidity of the solder layer is explored in different brazing heating power and soldering time so as to find a suitable high-proficiency brazing process for this studyand make the fine-grained brazing diamond wheel.2. The diamond rolling wheel is used to modify the soldering grinding wheel. Theresults show that wheel’s radical beating and its surface’s roughness are obviouslyreduced and the grinding force, with the increasing amount of the modification,increases at first and then gradually levels off. After the modification of the diamondrolling wheel, the main stages of the soldering diamond grinds include rubdown,micro-cracking, large crushing, and breaking off and so on.3. The fine-grained soldering diamond wheel is used to grind brittle materials suchas yttrium vanadate crystal, alumina ceramics and Mongolia black granite. The resultsshow that the most significant impact on the grinding force is the grinding depth.During the grinding process, grinding force and grinding force ratio of aluminaceramic is the largest, while grinding force and grinding force ratio of yttriumvanadate crystal is the smallest.4. Through analyzing the impact of grinding parameters on the grinding surface’sroughness, it shows that surface roughness of the vertical grinding direction is greaterthan that of the parallel grinding direction. With the same grinding parameters, thesurface of Mongolia black granite the roughest while the alumina ceramic’s surface isthe smoothest.5. Through observing the surface appearance of the work-piece grinding by ESEM,it is found that there are concave pits caused by the crystal’s cracking and peeling-offexcept furrows and smooth areas. If the grinding parameters change, the surfaceappearance will change. The smooth areas increase when grinding wheel’s linearspeed increases; the concave pits increase when the grinding depth and feeding speedof work-piece increase. |
PDF Full Text Request