U71Mn钢轨成形磨削表面完整性实验研究

Experimental investigation on the surface integrity of U71Mn rail via form-grinding

  • 摘要: 钢轨成形磨削加工旨在延长钢轨寿命并改善轮/轨接触关系,但当前对成形磨削加工后钢轨表面完整性尚缺乏系统性研究。基于此,采用单因素对照实验系统性研究成形磨削参数对U71Mn钢轨磨削表面完整性的影响。首先,使用钢轨磨削加工平台研究钢轨进给速度、砂轮磨削深度和线速度的变化对已加工表面完整性的影响;其次,分析球形磨屑和带状磨屑的形貌及能谱。研究结果表明,进给速度和磨削深度增大使Ra增大60%和123.02%,Rz增大18.92%和23.16%;砂轮线速度增大使Ra和Rz减小29.29%和18.03%。进给速度为0.65 m/min,磨削深度为0.13 mm,砂轮线速度为21.67 m/s时,亚表面塑性变形层厚度分别达到最大值10、15和13 μm。显微硬度呈先降低后平稳的趋势。磨削产生的球形磨屑含氧量为36.65%,远高于带状磨屑。

     

    Abstract: Rail form grinding is aimed at extending the lifespan of rails and improving the wheel/rail contact relationship. However, there is still a lack of systematic investigations on the machined surface integrity of rails after form grinding at present. Based on this, a single-factor experimental approach was performed to systematically study the effects of grinding parameters on the surface integrity of U71Mn rails. Firstly, a rail form-grinding machining platform was utilized to investigate the effects of feed speed, grinding depth, and wheel peripheral velocity on the surface integrity. Secondly, the morphology and energy spectrum of spherical and ribbon-shaped grinding chips were analyzed. The results show that increasing the feed rate and grinding depth increases Ra by 60% and 123.02%, and Rz by 18.92% and 23.16%, respectively; increasing the wheel peripheral velocity reduces Ra and Rz by 29.29% and 18.03%, respectively. When the feed speed is 0.65 m/min, the grinding depth is 0.13 mm, and the wheel peripheral velocity is 21.67 m/s, the thickness of the subsurface plastic deformation layer reaches the maximum values of 10 μm, 15 μm and 13 μm, respectively. The microhardness shows a trend of first decreasing and then stabilizing. The oxygen content of the spherical grinding chips produced by grinding is 36.65%, which is much higher than that of the ribbon-shaped grinding chips.

     

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