Authors: Hui Huang, H.M. Zhu, Xi Peng Xu
146
Authors: Hong Hua Su, Hong Jun Xu, Bing Xiao, Yu Can Fu, Jiu Hua Xu
Abstract: A new method for fabricating the thin-walled diamond core drill by brazing technology
and the optimum grain distribution was proposed in this paper. Machining performance experiments have been carried out, including contrast tests about drill life and machining efficiency for the thin- walled monolayer brazed diamond core drill and electroplated one. The testing results show that thin-walled monolayer brazed diamond core drill has certainly super-excellent machining performance. Wear mechanism of diamond grits was studied in tho se drilling processes. No pulling out for the thin-walled monolayer brazed diamond core drill grits is the key factor of its longer life, and the optimum grain distribution and less wear flat of grits during drilling decrease the drilling spindle direction force, and improve the machining efficiency. It can be concluded that the new technology can radically improve the bonding strength at the grains interface, and make every grain effective during drilling.
287
Authors: Jiu Hua Xu, Wen Feng Ding, F. Qian
Abstract: The joining strength and corresponding fracture mechanism of the brazing interface
between diamond grains and tool matrix is one of the primary problems in the development and
application of brazed diamond grinding tools. In this study shearing tests were performed for the
brazed joints, meanwhile the fracture mechanism and the joining characteristics were analyzed
deeply. The results indicate that, depending on the metallurgical integration effect through the atom
diffusion between the filler alloy and the metal matrix, and on the strong chemical bond by the
new-formed Cr-C compounds between the filler alloy and diamond grains, hard and reliable joining
is realized at the grain interfaces, which significantly supports the potential advantages of the latest
brazed diamond grinding tools.
501
Authors: Shu Sheng Li, Jiu Hua Xu, Bing Xiao, Ming Hua Yan, Yu Can Fu, Hong Jun Xu
Abstract: A kind of brazed monolayer diamond grinding wheel was developed with a relatively
regular distribution of grains on the wheel surface. Grinding performances of this kind of brazed
wheel in the surface grinding of cemented carbide were studied. The experiment results show that the
grinding forces ratio becomes higher with the increasing of the maximum undeformed chip thickness
and the specific energy falls with the material removal rate during grinding cemented carbide process.
Under certain grinding conditions, the material was removed almost through plastic deformation and
good surface quality is gained. Furthermore, the grits of the brazed diamond grinding wheel fail
mainly in attritious wear modes other than pull-out ones in conventional electroplated and sintered
diamond tools, which indicates that the strong retention of brazing alloy to the diamond grits and
longer service life of this kind of wheel.
381
Authors: Bing Xiao, Hong Jun Xu, Hong Hua Su, Yu Can Fu, Jiu Hua Xu
Abstract: An attempt has been made to investigate the new generational manufacturing technology for multi-layer diamond tools by brazing. A kind of new multi-layer brazed diamond core drills with random grains distribution was made by mixing diamond particles with brazing alloy powders. And a preliminary machining performance experiment was carried out through drilling granite. The testing results show the typical topography of the multi-layer brazed diamond core drills after drilling granite, just like that of multi-layer sintered ones, is that diamond grits drag long tails. Different from multi-layer sintered diamond core drills, no grit pull-outs can be seen during the whole drilling process because of chemical metallurgical effect between diamond grit and brazing alloy, the same as monolayer brazed diamond core drills. The main drawback to this kind of multi-layer brazed diamond tools is each individual particle is not subjected to the same drilling force throughout the drilling operation because of random grain distribution. This leads to premature fracture of the leading particles. Similarly, because large gaps between particles exist, the bond is being exposed to the workpiece, which leads to erosion of the bond. The overall performance is lower tool lives and slower drilling speeds. Therefore, ideally, diamond particles should be evenly distributed throughout the bond, which means they are all subject to the same drilling forces and the multi-layer brazed diamond tool is operated at its optimum efficiency.
598
