Fundamental Research On Fabrication And Application Technology Of Metal Bonded Diamond Tools

The metal-bonded diamond abrasive tools fabricated by hot-press sintering technique have been applied for over forty years. The inherent shortcomings and disadvantages have also appeared, and the most important points are as follows: the low bonding strength to the abrasive grains and the induced easy pullout of the grains from the matrix, the difficult outcrop and holding capacity of the cutting edge in the machining process, the unmatched grain load to the grinding practice owing to the stochastic grain distribution.On the basis of the research on the metal-bonded diamond abrasive tools in recent years, new investigation are conducted from the following aspects, including the joining strength to the grains, the thermal damage of the abrasive, the hole structure and the optimum distribution of grains. The new-type metal-bonded diamond abrasive tools with multi-hole structure are fabricated and show outstanding advantages over the traditional tools in the machining experiments.The main creative concepts are summarized as follows:(1) The brazing effect of the diamond grains is analyzed from three aspects, such as the diamond shape and the interfacial microstructure, the joining strength, the behavior of the grains during machining. The key brazing technology is acquired to ensure the high joining strength and avoid the thermal damage of the diamond grain.(2) The new technology is put forward to fabricate the multi-hole metal-bonded diamond abrasive tools in the loose liquid-phase sintering process. The steady solid framework forms through the loose technique. The ratio and size of the hole are adjusted by the pore producer. At the same time, the filler alloy, which has ever been utilized to braze diamond grain, is applied to wet and spread on the solid framework. The diamond grain could join hard with the framework. The sintered specimens are accomplished. Compared with the traditional technology of the metal-bonded diamond abrasive tools, the diamond tools fabricated using the new technology in this investigation could improve the pore ratio and the joining strength under the condition of the identical specimen strength.(3) The slotted multi-hole metal-bonded diamond grinding wheels for high efficiency precision grinding are fabricated using the loose liquid phase sintering technology. The machining experiments detect that this new diamond tool with rather low density of the grains could grind precisely Al2O3 engineering ceramics. The low surface roughness reaches. Moreover, the characteristics, i.e. the low grinding force, the sharp edge and long tool life, the high material removal rate is also evident. (4) The multi-layer metal-bonded diamond sawing blades for cutting difficult-to-machine materials are fabricated using the comprehensive technology of both the uniform distribution of the diamond grain and the conventional hot-press sintering technology. The machining experiments are carried out between the new blades and the merchant counterparts with diameter of 350mm. The result indicates that the new tools have some topping merits, including small quantity of grains, shape edge, high machining efficiency and long tool life.The creative work on the multi-layer metal-bonded diamond abrasive tools in this investigation could accelerate markedly the research and the application of the diamond tools around the world.