As an important green manufacturing process, dry grinding has problems such as high grinding temperature and insufficient cooling capacity. Aiming at the problems of sticking and burns in dry grinding of titanium alloys, grinding performance evaluation of molybdenum disulfide (MoS2) solid lubricant coated brazed cubic boron carbide (CBN) grinding wheel (MoS2-coated CBN wheel) in dry grinding titanium alloys was carried out. The lubrication mechanism of MoS2 in the grinding process is analyzed, and the MoS2-coated CBN wheel is prepared. The results show that the MoS2 solid lubricant can form a lubricating film on the ground surface and reduce the friction coefficient and grinding force. Within the experimental parameters, normal grinding force decreased by 42.5%, and tangential grinding force decreased by 28.1%. MoS2 lubricant can effectively improve the heat dissipation effect of titanium alloy grinding arc area. Compared with ordinary CBN grinding wheel, MoS2-coated CBN wheel has lower grinding temperature. When the grinding depth reaches 20 µm, the grinding temperature decreased by 30.5%. The wear of CBN grains of grinding wheel were analyzed by mathematical statistical method. MoS2 lubricating coating can essentially decrease the wear of grains, reduce the adhesion of titanium alloy chip, prolong the service life of grinding wheel, and help to enhance the surface quality of workpiece. This research provides high-quality and efficient technical support for titanium alloy grinding.
Super high-strength steel has an important demand in manufacturing key components inside gear transmission systems of heavy-duty helicopter owing to its superior comprehensive mechanical property. However, the high-performance machining of super high-strength steel is confronted with great challenges owing to the high cutting force, serious tool wear, and impoverished machining quality. Comparative trials in grinding ultra-high strength steel under conventional grinding (CG) and ultrasonic vibration-assisted grinding (UVAG) processes was conducted with white alumina (WA) and microcrystalline alumina (MA) wheels. Grinding performances, including grinding forces, force ratio, ground surface quality, and abrasive wheel morphologies were discussed in detail. Experimental results show that the separation property between wheels and workpiece in UVAG process contributes to alter the material removal process, reducing the chip clogging and adhesion. In addition, the micro-fracture of abrasive grains can effectively improve the self-sharpening ability of abrasive wheels. UVAG possesses a shorter grinding scratch owing to the ultrasonic vibration than that of CG, which is beneficial to improve machining quality under the same wheel. Meanwhile, in comparison of WA wheels, MA wheels have the narrower grinding marks and better surface quality, which is due to the sharp edges produced by its higher strength, toughness and excellent self-sharpening.
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