The abrasives of grinding stone

Grinding stone commonly used abrasives for corundum class abrasives (zirconium corundum, brown corundum, white corundum, etc., such as Figure 11)[1,2] , some super-hard abrasives (CBN)[3] and SiC, WC, etc. Because diamond and transition metal element Fe has strong affinity, so in grinding high temperature diamond surface layer carbon atom sp3 hybridisation state into sp2+ 2P1z state, that is, diamond graphitization, reduce the abrasive grinding performance[4,5] This reduces the grinding performance of the abrasive, and thus diamond is not suitable for rail grinding. Although CBN abrasive strong / toughness, and high temperature resistance, wear resistance, good thermal conductivity, strong grinding ability[6,7] Although CBN abrasives are strong/tough, high temperature resistant, wear resistant, good thermal conductivity, strong grinding ability, but its particle size is small (the largest particle size less than 500 μm), high price, it is difficult to reflect the advantages of its grinding performance in the rail grinding of this kind of coarse grinding and heavy load conditions, and the grinding stone economy is poor. Corundum abrasives have good wear resistance, strong/toughness, and cutting ability, low cost, in the rail grinding class of high-speed, high load, dry grinding, coarse grain size and other extreme operating conditions have ignificant advantages. Zhang Wulin[8] The compressive strengths of zirconium corundum, calcined brown corundum and white corundum and the grinding performance of corresponding grinding stones of F16 were examined using a uniaxial compression test device, and the results showed that: the strength of zirconium corundum was the highest (308.0 MPa), followed by calcined brown corundum (124.0 MPa), and the lowest one was white corundum (103.2 MPa); and the grinding ratios of the zirconium, calcined brown corundum and white corundum abrasive grinding stones, in order of magnitude, were 41.0, 22.4, and 11.9; therefore, strong/tough and chemically stable corundum abrasives, especially zirconium corundum and brown corundum, are commonly used in the manufacture of rail grinding stones.[9,10,2] Therefore, the manufacture of rail grinding whetstone generally uses strong/tough and chemically stable corundum type abrasives, especially zirconium corundum and brown corundum. At present, the global high-performance zirconium corundum abrasive smelting technology is mastered by French Saint-Gobain and other enterprises. Therefore, breaking through the key technological bottleneck of zirconium corundum smelting and developing high-performance (high toughness, wear resistance, heat resistance, good self-sharpness, etc.) zirconium corundum abrasives are crucial for the improvement of grinding stone performance.

Fig. 1.  Zirconium corundum abrasives[1] 

Fig. 2. White corundum abrasives[1] 

Fig. 3.Brown corundum abrasives[1] 

At present, grinding stones for line rail grinding are manufactured with a mixture of abrasives of different grain sizes and types.Wang et al.[50] studied the grinding performance of grinding stones with different ratios of zirconium corundum and brown corundum, and the results showed that with the increase of brown corundum content (0%~100%), the grinding volume of grinding stones decreased. Comprehensive comparative results indicate that the addition of 10%~30% of brown corundum to the whetstone can ensure that the whetstone has a more desirable grinding efficiency and also reduce the manufacturing cost of the whetstone.Zhang et al.[11] investigated the grinding behaviour of grinding stones with different abrasive grain sizes (F10~F30), and the results showed that under a certain load, with the reduction of abrasive grain size, the main grinding mechanism of the grinding stone gradually changed from sliding friction and ploughing to cutting, and the grinding performance of the grinding stone and the surface quality of the polished rails were both improved. In the subsequent study, Zhang et al.[1] continued to study the mechanical properties of zirconium corundum, brown corundum and white corundum abrasives and the grinding behaviour of the corresponding whetstone, and the results showed that the mechanical properties of the abrasives were one of the fundamental reasons affecting the grinding performance of the whetstone.Wang et al.[12] The results of the study showed that the grinding vibration increased with the decrease of the grain size of the grinding stone abrasive. Although a large amount of research work has been carried out around the grinding stone abrasives, the regulatory mechanism of the abrasive structure (geometry, type, grain size, ratio, etc.) on the physical and chemical properties of the grinding stone (toughness/toughness, strength, heat resistance, wear resistance, etc.) and the service performance (amount of grinding, grinding ratio, service life, mileage in service, failure mechanism, and the quality of the surface of the rail after grinding) is still unclear.

[1] ZHANG Wulin, LIU Changbao, YUAN Yongjie, et al. Probing the Effect of Abrasive Wear on the Grinding Performance of Rail Grinding Stones[J]. Journal of Manufacturing Processes, 2021, 64: 493-507.

[2] WANG Ruixiang, ZHOU Kun, YANG Jinyu, et al. Effects of Abrasive Material and Hardness of Grinding Wheel on Rail Grinding Behaviors[J]. Wear, 2020, 454-455: 203332.

[3] HUNAG Guigang. Design and Experimental Study of High Speed Grinding Test Bench for Rail CBN Grinding Wheel[J]. Manufacturing Automation, , 2020, 42(05): 88-91+122.

[4] PENG Jin, ZOU Wenjun. Organic Abrasive Tools[M]. Zhengzhou: Zhengzhou University Press, 102-244.

[5] LI Boming, ZHAO Bo, LI Qing. Abrasives, Abrasive Tools and Grinding Technology[M]. Second Edition. Beijing: Chemical Industry Press, 2016, 45-270.

[6] ZHAO Biao, DING Wenfeng, CHEN Zhenzhen, et al. Pore Structure Design and Grinding Performance of Porous Metal-bonded CBN Abrasive Wheels Fabricated by Vacuum Sintering[J]. Journal of Manufacturing Processes, 2019, 44: 125-132.

[7] ZHANG Wulin, ZHANG Pengfei, ZHANG Jun, et al. Probing the Effect of Abrasive Grit Size on Rail Grinding Behaviors[J]. Journal of Manufacturing Processes, 2020, 53: 388-395.

[8] ZHANG Wulin. Study on the Performances Regulatory Mechanisms of High-speed Rail Grinding Stone via Corundum Abrasives[D]. Chengdu: Southwest Jiaotong University, 2021.

[9] YUAN Yongjie, ZHANG Wulin, ZHANG Pengfei, et al. Porous Grinding Wheels Toward Alleviating the Pre-fatigue and Increasing the Material Removal Efficiency for Rail Grinding[J]. Tribology International, 2021, 154: 106692

[10] ZHOU Kun, DING Haohao, WANG Ruixiang, et al. Experimental Investigation on Material Removal Mechanism During Rail Grinding at Different Forward Speeds [J]. Tribology International, 2020, 143: 106040.

[11] ZHANG Wulin, ZHANG Pengfei, ZHANG Jun, et al. Probing the Effect of Abrasive Grit Size on Rail Grinding Behaviors[J]. Journal of Manufacturing Processes, 2020, 53: 388-395.

[12] WANG Wenjian, GU Kaikai, ZHOU Kun, et al. Influence of Granularity of Grinding Stone on Grinding Force and Material Removal in the Rail Grinding Process[J J]. Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 2019, 233(2): 355-365.