在往复测试中生成Stribeck曲线
Stribeck曲线这一术语用于描述一个阴谋showing the frictional characteristics of a liquid lubricant over conditions usually spanning the Boundary, Mixed and Hydrodynamic regimes. Each regime is defined by the ratio of the film thickness to the surface roughness, or the λ ratio (Figure 1). Such curves are often used to evaluate the effect of changes to the lubricant’s viscosity or to the lubricant’s additive package, or the effect of surface roughness. The primary requirement for generating a Stribeck curve is a fluid that can be drawn into a converging gap, thus creating a pressure increase to support the load (Figure 2).
Historical/Traditional Test Geometry
The classic work of Thurston1，马滕斯2，stribeck3和赫尔4是使用日志含有几何形状完成的，该几何形状具有上述所有要求（图3）。仪器携带的测试允许在一系列相对速度和/或负载范围内评估摩擦。在Stribeck曲线中，绘制摩擦系数（COF）的关键参数称为HERSEY编号。HERSEY编号是从速度（m/s）获得动态粘度（PA∙S=N∙S/M2）的无量纲数，除以轴承的单位长度（N/M）的负载。
The simplest method to obtain a Stribeck curve and the method most commonly used, provided one has the appropriate converging gap geometry, is to keep two variables fixed (e.g., load and viscosity) and vary the third (e.g., velocity) over a suitable range so that the contact interface goes through the region of asperity contact (boundary), as well as full fluid-film separation (hydrodynamic). In the laboratory this is most easily done in a unidirectional manner using a pin-on-side against a rotating disk (POD) under flooded lubrication, with the pin-end contact geometry creating the converging gap.
互动运动的曲线曲线生成
然而，最近，使用往复测试模式评估润滑剂摩擦特性已经引起了极大的兴趣。这种测试钻机有时被称为高频往复钻机（HFRR）或SRV型测试。（SRV是德语表达式Schwingung ReibungVerschleiß的首字母缩写，这意味着摩擦和磨损）。如何使用往复测试模式的一个示例是模拟汽车发动机中气缸中活塞环的润滑条件。
在往复式模式下开发Stribeck曲线的挑战是在逆转之前长期发展足够长的速度，以建立达到流体动力润滑方案所需的压力和膜厚度。本注释使用高频往复运动的条件下，使用抛光的圆柱销钉的几何形状与高度抛光的平板相对于高度抛光的平板进行了测试。为这项工作设置了配备加热高速往复阶段的布鲁克UMT Tribolab（图4）。
在这样的高频回报钻机（HFRR）中，30 Hz条件的平均速度为0.42 m/sec，最大速度为0.59 m/sec，足够高，足以达到流体动力润滑方案。标准圆柱销钉销（直径为9.5毫米x 15.5毫米长，粗糙度为19 µm Ra）在旋转的自我对准固定器中固定，并在高度抛光的52100钢板（0.013 µm RA）上装载。图5A显示了测试室中的样品。作为圆柱形销钉侧和平板的替代方案，也可以使用由实际组件制成的样品（图5B）。
中风长度固定为7 mm，所有测试的载荷在20 N处固定，并且频率从0.1 Hz到30 Hz的变化。使用了三种不同的粘度多α烯烃（PAO），即PAO-2，PAO-10和PAO-40（仪表板数字是指100°C时CST的粘度）。在室温下进行测试。图6显示了这三种粘度润滑剂的测试所产生的Stribeck曲线。
Additional Standard Reciprocating Test Capabilities
While there is currently no standard published test method for generating a Stribeck curve, either in reciprocating or unidirectional motion, a number of other lubricant performance-related tests can be conducted with the same reciprocating motion for the lower sample. By exchanging the cylinder-on-side upper sample for either a ball or a flat-pin, and adjusting the frequency and/or stroke-length, the same setup can be used to run the following standard ASTM-, DIN- or ISO-issued reciprocating tests:
ASTM D5706-11:Standard test method for determining extreme pressure properties of lubricating greases using a high-frequency, linear-oscillation (SRV) test machine
ASTM D5707-11：使用高频，线性振荡（SRV）测试机测量润滑油脂的摩擦和磨损特性的标准测试方法
ASTM D6425：Standard test method for measuring friction and wear properties of extreme pressure lubricating oil
ASTM D6079-11：高频往复钻机（HFRR）评估柴油燃料润滑性的标准测试方法
ASTM D7688-11：高频往复钻机（HFRR）评估柴油燃料润滑性的标准测试方法by visual observation
ASTM D7594-11：标准测试方法，用于使用高频，线性振荡（SRV）测试机在高赫兹（Hertzian）接触压力下在高赫兹（Hertzian
ASTM D7755-11：Standard practice for determiningthe wear volume on standard test pieces used by high- frequency, linear-oscillation (SRV) test machine
ASTM G133-10：线性往复的标准测试方法
ASTM G203-10:Standard guide for determining friction energy dissipation in reciprocating tribosystems
ASTM G206-11：Standard guide for measuring the wear volumes of piston ring segments run against flat coupons in reciprocating wear tests
DIN 51834：确定摩擦和磨损润滑油数据
ISO 12156-1：2006：柴油燃料 - 使用高频往复钻机（HFRR）评估润滑性，Part 1: Test
作者
史蒂夫·谢弗（Steve Shaffer）博士
布鲁克Senior Applications Scientist
References
- 瑟斯顿（Thurston），罗伯特·H（Robert H.
- Martens, Adolf, Schmieröluntersuchungen [oil studies], Mitteilungen aus den Königlichen Technischen Versuchsanstalten zu Berlin, Ergänzungsheft III [releases from the Royal Technical Testing Institutes of Berlin, complementary volume III], Julius Springer, Berlin, 1888, 1–37.
- 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和1463 –70。
- Hersey, Mayo, The Laws of Lubrication of Horizontal Journal Bearings, Journal of the Washington Academy of Sciences, 4, 1914.
- 摩擦学和润滑工程师学会 - www.stle.org
