Recently, the emerging rail grinding method using abrasive belt has been proposed to efficiently achieve the required geometric profile and the surface quality of the railhead. Although the abrasive features indeed have a great influence on this rail grinding process, the surface topography of abrasive belt regarding grits at the microscopic scale is neglected. In this article, a microscopic contact pressure model was developed to reveal the contact behavior of every active grit based on the digital representation of the surface topography of abrasive belt. Then a numerical model of material removal quantity was also established based on the consideration of the characteristics of abrasive grits and their interactions. Finally, the series of finite element simulations and grinding tests were successively implemented. The normal load and the surface topography of abrasive belt significantly affected the microscopic contact behavior of grits, thus confirming the proposed theoretical models of microscopic contact pressure and material removal quantity.

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In order to reduce vehicle weight and improve crash performance, dual-phase (DP) steels are increasingly used for lightweight auto-body. the high cooling rates in Resistance spot welding (RSW) process will make the nugget very brittle and result in interfacial fracture modes. In this study, a servo resistance welding system is firstly introduced to control process parameters during the welding process. The influences of different process parameters (weld current, weld time and electrode force) on the weld strength, nugget diameter, facture modes and weld indentation are analyzed. Finally, an on-line weld failure mode inspection method is proposed based on servo gun’s feedback characteristics.

The current research of abrasive belt grinding rail mainly focuses on the contact mechanism and structural design. Compared with the closed structure abrasive belt grinding, open-structured abrasive belt grinding has excellent performance in dynamic stability, consistency of grinding quality, extension of grinding mileage and improvement of working efficiency. However, in the contact structure design, the open-structured abrasive belt grinding rail using a profiling pressure grinding plate and the closed structure abrasive belt using the contact wheel are different, and the contact mechanisms of the two are different. In this paper, based on the conformal contact and Hertz theory, the contact mechanism of the pressure grinding plate, abrasive belt and rail is analyzed. Through finite element simulation and static pressure experiment, the contact behavior of pressure grinding plate, abrasive belt and rail under single concentrated force, uniform force and multiple concentrated force was studied, and the distribution characteristics of contact stress on rail surface were observed. The results show that under the same external load, there are three contact areas under the three loading modes. The outer contour of the middle contact area is rectangular, and the inner contour is elliptical. In the contact area at both ends, the stress is extremely small under a single concentrated force, the internal stress is drop-shaped under a uniform force, and the internal stress under multiple concentration forces is elliptical. Compared with the three, the maximum stress is the smallest and the stress distribution is more uniform under multiple concentrated forces. Therefore, the multiple concentrated forces is the best grinding pressure loading mode. The research provides support for the application of rail grinding with open-structured abrasive belt based on pressure grinding plate, such as contact mechanism and grinding pressure mode selection.