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Ultra-high strength steel has a wide application of gear transmission systems in the aerospace field, owing to its high hardness, good impact toughness, fracture toughness, etc. Grinding is the important method to guarantee the final quality of ultra-high strength gears. However, the service life of grinding wheels is seriously shortened due on the numerous reinforced particles inside the hardened layer on gear surface, deteriorating the ground quality eventually. In order to resolve this issue, ultrasonic vibration-assisted grinding (UVAG) technology is applied, and then comparative trials are conducted between UVAG and conventional grinding (CG) during ultra-high strength steel machining. Here, the grinding performance, such as the variation of grinding force and temperature under two grinding modes, and the variation of tool wear morphology with the increase of grinding step are analyzed. Subsequently, the grinding surface quality of UVAG process is discussed in view of ground surface roughness and surface morphology. Results show that the CG possesses a rapid increase in grinding forces and temperature, and eventually, surface quality deteriorates gradually, whereas they have been improved in UVAG. In the range of experimental parameters, the force Fn and temperature of grinding maximum decreased by 35.5 and 39.2%, respectively, compared with CG. Moreover, due to the self-sharpening of abrasive grains, the UVAG process produces a finer ground surface quality. The research provides technical support for high quality and efficient machining of ultra-high strength aviation transmission gear. [ABSTRACT FROM AUTHOR]

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 were 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. [ABSTRACT FROM AUTHOR]

Ultrasonic vibration-assisted grinding (UVAG) is a highly effective technique for improving the grindability of difficult-to-cut materials, making it widely applicable in various industrial fields. However, the conventional optimization of grinding parameters necessitates extensive experimental analyses and is susceptible to converging towards a local optimum. A multiobjective particle swarm optimization (MOPSO) model is developed in this study to predict grinding forces and surface roughness based on comparative experiments between UVAG and conventional grinding. Optimized process parameters are utilized to perform experiments on ultrasonic vibration-assisted profile grinding, resulting in a reduction of 20.51% and 18.91% in tangential and normal grinding forces, respectively, as well as a decrease of 9.47% in ground surface roughness. In addition, UVAG can maintain the sharpness of grinding wheels. The MOPSO algorithm yields a Pareto solution set comprising 15 noninferior solutions, indicating that superior surface roughness is achieved by increasing wheel speed and cutting depth while decreasing feed speed. The ultrasonic vibration-assisted profile grinding process enables the formation of workpieces with exceptional shape accuracy and high surface quality, while also optimizing machining parameters. [ABSTRACT FROM AUTHOR]

The combination of ultrasonic vibration-assisted grinding (UVAG), the ultrasonic vibrating method, and the conventional grinding (CG) process is proposed to improve the grindability of hardened steel in the CG process. Comparative investigations on grinding force, temperature, and specific grinding energy for both grinding processes were conducted. In addition, the morphologies of the wheel wear and ground surfaces were also studied. Findings show that compared with the CG processes, the normal and tangential grinding forces in UVAG are reduced greatly by 16.44% and 17.44%, respectively. The UVAG process decreases the specific grinding energy by 8.30% owing to the increase of the maximum undeformed chip thickness and the grinding temperature by 19.01% due to the improvement of the coolant heat transfer capacity in the grinding arc zone. Meanwhile, the promising grain sharpness of wheels can be guaranteed from the enhanced cooling function on the grinding arc zone and the grain's micro-fracture caused by ultrasonic impacting actions. [ABSTRACT FROM AUTHOR]