The Development Of Porous Metal Bonded Diamond Grinding Wheels

Diamond grinding wheels are widely used as grinding tools in manufacturing of hard and brittle materials, such as hard alloy, engineering ceramics, optical glass, semiconductor materials, and granite. Metal bonded diamond grinding wheels have good shape retention because of their high bond strength and Stiffness. So metal bonded diamond grinding wheels are mainly used in accurate grinding and ultra precise grinding. However, the traditional metal diamond grinding wheels almost have no pores, which make the wheels have poor self-sharpening, be easy blocked up and difficult to be dressing and truing. This results in low grinding efficiency. Therefore, how to keep abrasive grains sharpened while assuring metal bond have high diamond retention capacity is a key problem in order to achieve high grinding efficiency.In order to improve the self-sharpening ability and increase the clearance for debris of metal bonded diamond wheel, two kinds of appropriate pore inducers were chosen to fabricate the highly porous metal-bonded diamond composites for grinding wheel in this paper. The pore inducers were selected after trying different kinds of pore inducers. By orthogonal test and variance analysis, relationship between porosity and the quantities of the pore inducers, and relationship between transverse rupture strength (TRS) and the porosity were studied. The effects of rare earth and TiH2 on the microstructures and the TRS of diamond composite were also studied. Finally, diamond wheels without additives of pore inducers and with appropriate amount of pore inducers were fabricated. The porosity of diamond wheel without additives of pore inducers is 7% and the wheel with pore inducers is 38%. Grinding experiments with these two sintered diamond grinding wheels on marbles were carried out under different grinding conditions. The grinding forces were measured, the worn pattern of diamond wheels was observed by 3D video system, and the comprehensive abilities of the wheels were evaluated.The main experimental results in this dissertation are summarized as follows:(1) By varying the quantity of the two kinds of appropriate pore inducers, diamond composites with porosity ranging from 7 % to 46 % in volume and metal bonds with porosity ranging from 5 % to 50 % in volume were obtained. Correspondingly, the bending strength of diamond composites and the metal bonds ranged from 292MPa to 19.8MPa and from 633MPa to 34MPa respectively.(2) There were good relationships between porosity and the quantity of the pore inducers as well as transverse rupture strength (TRS) and the porosity. Their relationships can be expressed by regression equations.