ISSN   1004-0595

CN  62-1224/O4

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Cr12MoV模具钢表面微织构润滑减阻研究

Research on Surface Micro-Texture Lubrication and Drag Reduction of Cr12MoV Mold Steel

  • 摘要: 表面微织构在润滑减阻方面具有优秀的性能表现,被广泛应用于轴承润滑和刀具减阻等领域. Cr12MoV模具钢为航天机电伺服机构中的重要材料之一,为降低其相对接触面的摩擦阻力、提升机构的传动效率和可靠性,通过ANSYS Fluent软件进行流体力学仿真,分析不同微织构对摩擦副润滑性能的影响,并采用飞秒激光加工模具钢表面微织构,结合摩擦磨损试验进一步研究其织构化处理的最优织构形貌. 研究发现:菱形形貌的织构能够更有效地诱导和增强流体的涡旋等不规则运动,增大惯性效应及空化效应的影响;在试验温度为40 ℃的条件下,摩擦副表面间的相对速度对Cr12MoV模具钢的摩擦润滑性能影响较大,负载、织构形貌及织构间距影响较小;最优菱形织构参数相较于无织构表面摩擦系数降低37.74%.

     

    Abstract: Surface micro-texture demonstrates outstanding performance in lubrication and drag reduction, and is extensively utilized in areas such as mechanical seal, cylinder liner-piston ring, bearing lubrication, tool drag reduction and others. With the continuous enhancement of the power level of aerospace electromechanical servomechanism and the increasingly severe service environment, the friction performance between the slide valve pairs, which is the key components of the servo valve where motion contact occurs is gaining growing significance. The sliding interface of the slide valve pairs of the servo valve has emerged as the primary factor influencing the precise random movement of the servo valve in accordance with the system command signal. There exists sliding friction between the valve core and the valve sleeve, featuring a small contact area, a short reciprocating distance and a high friction frequency. Hence, the influence of friction and wear is more substantial, which will not only lower the transmission efficiency, but also impact the reliability and service life of the mechanism. Cr12MoV mold steel is one of the essential materials of the slide valve pairs within the aerospace electromechanical servomechanism. To diminish the frictional resistance of the relative contact surface, enhance the transmission efficiency and reliability of the mechanism, hydrodynamic simulation on the micro-textures of square, circle, rhombus and regular hexagonal shapes was conducted by employing ANSYS Fluent software under various micro-texture spacings, depths and different minimum oil film thicknesses with the aim of analyzing the influence of different micro-textures on the lubrication performance of friction pairs. Moreover, the surface micro-textures of Cr12MoV mold steel were fabricated by femtosecond laser. Coupled with the friction and wear test, further research was carried out on the optimal micro-texture morphology of the texture treatment. The results demonstrated that the rhombus micro-texture could more effectively induce and enhance the irregular movement of fluids, such as vortices and augment the influence of the inertia effect. The rapid alteration of the local velocity of the fluid was prone to cause the reduction of local pressure to form bubbles, which providing advantageous conditions for the emergence of the cavitation effect. Under the test temperature of 40 ℃, the relative speed between the friction pair surfaces exerted a significant influence on the tribological lubrication properties of Cr12MoV mold steel, while the load, the micro-texture morphology and the micro-texture spacing had less influence. Compared with the surface without micro-texture, the resistance reduction rate of the optimal rhombus micro-texture parameter was 37.74%. Additionally, through SEM and confocal 3D wear topography, it was discovered that the surface micro-texture was beneficial for the formation of the lubricating oil film between the friction pairs of Cr12MoV mold steel, reducing the risk of direct contact between the friction pairs and enhancing the wear resistance.

     

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