Generating a Stribeck Curve in a Reciprocating Test
术语stribeck曲线用于描述一个图表，显示了通常跨越边界，混合和流体动力学的条件下液体润滑剂的摩擦特性。每个制度都是由膜厚度与表面粗糙度或λ比的比率定义的（图1）。这种曲线通常用于评估润滑剂粘度或润滑剂添加剂套件的变化的影响，或表面粗糙度的效果。生成Stribeck曲线的主要要求是可以将其吸引到收敛间隙中的流体，从而产生压力增加以支撑负载（图2）。
历史/传统测试几何形状
瑟斯顿的经典作品1, Martens2, Stribeck3and Hersey4were done using a journal-bearing geometry, which possesses all of the above requirements (Figure 3). An instrumented journal-bearing test allows for evaluation of the friction over a range of relative velocities and/or loads. In a Stribeck curve the key parameter, against which the coefficient of friction (COF) is plotted, is called the Hersey number. The Hersey number is the dimensionless number obtained from the velocity (m/s) times the dynamic viscosity (Pa∙s = N∙s/m2), divided by the load per unit length of bearing (N/m).
获得stribeck曲线的最简单方法和最常用的方法（只要一种具有适当的收敛差距几何形状）是将两个变量保持固定（例如负载和粘度），并在适当的范围内改变第三个变量（例如，速度）因此，接触界面穿过腹膜触点（边界）的区域以及全流体形式的分离（流体动力学）。在实验室中，这是最容易以单向方式进行的，使用针对旋转磁盘（POD）在洪水润滑下的旋转磁盘（POD）进行，而PIN-END接触几何形状产生了融合的间隙。
Reciprocating Motion for Stribeck Curve Generation
Recently, however, there has been considerable interest in evaluating lubricant frictional characteristics using a reciprocating test mode. Such test rigs are sometimes referred to as a high-frequency reciprocating rig (HFRR) or SRV-type test. (SRV is an acronym for the German expression Schwingung Reibung Verschleiß, which meansreciprocating friction and wear). An example of how a reciprocating test mode might be used is to simulate the lubrication condition of a piston ring in a cylinder in an automobile engine.
The challenge for developing a Stribeck curve in the reciprocating mode is to develop enough velocity, over a long enough stroke length before reversal, to build up the pressure and film thickness required to reach the hydrodynamic lubrication regime. This note describes such a test using the geometry of a polished cylindrical dowel pin- on-side against a highly polished flat plate, under conditions of high-frequency reciprocating motion. A Bruker UMT TriboLab (Figure 4), equipped with a heated high-speed reciprocating stage, was set up for this work.
In such a high-frequency reciprocating rig (HFRR), the 30 Hz conditions give an average velocity of 0.42 m/sec and a maximum at mid-stroke of 0.59 m/sec, high enough to reach the hydrodynamic lubrication regime. A standard cylindrical steel dowel pin (9.5 mm diameter x 15.5 mm long, roughness 19 µm Ra) was held in a pivoting self-aligning holder and loaded against a highly polished 52100 steel plate (0.013 µm Ra). Figure 5a shows the samples in the test chamber. As an alternative to the cylindrical pin-on-side and a flat plate, samples fabricated from actual components also can be used (Figure 5b).
The stroke length was fixed at 7 mm and the load at 20 N for all tests, and the frequency was varied from 0.1 Hz up to 30 Hz. Three different viscosity poly-alpha olephin oils (PAOs) were used, namely PAO-2, PAO-10 and PAO-40 (the dash number refers to the viscosity in cSt at 100°C). Tests were conducted at room temperature. Figure 6 shows the resulting Stribeck curves from tests of these three viscosity lubricants.
其他标准往复测试功能
虽然目前尚无标准公开的测试方法来产生Stribeck曲线，但无论是往复运动还是单向运动，可以使用许多其他与润滑性性能相关的测试，以相同的往复运动进行较低样品的相同往复运动。通过将圆柱体侧面样品交换为球或平钉，并调整频率和/或中风长度，可以使用相同的设置来运行以下标准ASTM-，DIN-或ISO--发行的往复测试：
ASTM D5706-11：使用高频，线性振荡（SRV）测试机确定润滑油脂极端压力特性的标准测试方法
ASTM D5707-11:Standard test method for measuring friction and wear properties of lubricating grease using a high-frequency, linear-oscillation (SRV) test machine
ASTM D6425:测量摩擦和磨损特性的标准测试方法
ASTM D6079-11:evaluat的标准试验方法ing lubricity of diesel fuels by the high-frequency reciprocating rig (HFRR)
ASTM D7688-11:通过视觉观察评估高频往复钻机（HFRR）评估柴油燃料润滑性的标准测试方法
ASTM D7594-11:Standard test method for determining fretting wear resistance of lubricating greases under high Hertzian contact pressures using a high-frequency, linear- oscillation (SRV) test machine
ASTM D7755-11:确定的标准实践高频，线性振荡（SRV）测试机使用的标准测试件上的磨损体积
ASTM G133-10:Standard test method for linearly reciprocating ball-on flat sliding wear
ASTM G203-10：确定往复式摩擦系统中摩擦能量耗散的标准指南
ASTM G206-11:测量活塞环节段磨损量的标准指南，反供应磨损测试的平面优惠券
DIN 51834:Determination of friction and wear data of lubricating oils
ISO 12156-1:2006:Diesel fuel — assessment of lubricity using the high-frequency reciprocating rig (HFRR),第1部分：测试
Author
Steve Shaffer, Ph.D.
布鲁克高级应用科学家
参考
- Thurston, Robert H., Determination of the Laws and Co-efficient of Friction by New Methods and with New Apparatus, Trübner and Co, London, 1879.
- Martens，Adolf，Schmieröluntersuchungen[石油研究]，Mitteilungen AusdenKöniglichenTechnisschen Versuchsanstalten Zu Berlin，ErgänzungsheftIII [从柏林的皇家技术测试中释放，III III II III II II II II III]，JULIUS SPRINGER，BERLIUS SPRINGER，BERLIUS，188888888。
- Stribeck, Richard, Die Wesentlichen Eigenschaften der Gleit- und Rollenlager [the main characteristics of the sliding and roller bearings], Zeitschrift des Vereins Deutscher Ingenieure [Journal of the Association of German Engineers] 36 (Band 46), 1902, 1341– 48,1432– 38, and 1463 –70.
- Hersey，Mayo，《水平期刊轴承润滑定律》，华盛顿科学院杂志，1914年，第4期。
- Society of Tribologists and Lubrication Engineers — www.stle.org
