Abstract:

At present, about 80% of rolling bearings are greased. The rheological properties of grease have an extremely important influence on the lubrication of rolling bearings. The rheological properties of grease cause the migration of base oil. The essence of this migration is the mass transfer process of the base oil in the grease. The mass transfer process of the grease in the rolling bearing has a very important influence on the lubrication of the bearing. In this process, due to the migration of the base oil in the grease, the distribution of the base oil in the grease is uneven, which causes the appearance of local areas with rich or lean oil. In this paper, the ash analysis method is used to study the mass transfer of grease at different rotation speeds and positions. The experimental conditions of different rotation speeds at different positions are experimentally studied by setting up the mass transfer separation characteristics test bench. The experimental rotation speeds of the separator are 100, 200, 400, 600, 800, 1000 r/min. At each rotation speed, the separation time was 0.5, 1 and 2 h. The grease is subjected to high-temperature sintering in a crucible to completely burn and decompose the grease, and the specific gravity of the ash and the grease is analyzed to determine the content of the base oil in the grease. The mass transfer phenomenon of grease is experimentally analyzed in detail. The research results show that when the rotation speed is 100 r/min, the mass transfer phenomenon of the base oil is obvious after a long time operation. When the rotation speed is 200—800 r/min, the base oil content in the internal position is higher, and the base oil content near the edge position is low and there is a lean state. When the rotation speed is 1000 r/min, the base oil undergoes a process of high to low and then high, and excessive migration of the base oil causes a lean condition. In the internal and intermediate positions, when the rotation speed is 800 r/min, the oil-poor state will be more obvious. At the edge position, the rotation speed is 100, 400 and 600 r/min will be more obvious. As a result of basic research, these results will lay the foundation for further research on rolling bearing grease lubrication.

Key words: distributions, centrifugation, mass transfer, grease, ash analysis

摘要：

目前，约有80%的滚动轴承采用脂润滑，润滑脂流变特性造成了基础油的迁徙，这种迁徙实质就是基础油在润滑脂内的传质过程。滚动轴承中润滑脂的传质过程对轴承润滑有非常重要的影响，在此过程中，由于基础油在润滑脂内的迁徙，造成了润滑脂内基础油的含量分布不均匀，使得局部区域内出现了富油和贫油的分布。本文采用灰分分析法对不同转速和位置润滑脂的传质情况进行了离心分离实验研究，对润滑脂的传质规律进行了详细研究。研究结果表明：当转速为100 r/min时，经过较长时间运行，基础油传质现象明显；当转速为200～800 r/min时，在内部位置基础油含量较高，靠近边缘位置基础油含量较低，出现贫油状态；当转速1000 r/min运行时，基础油发生了含量由高到低再变高的过程，基础油迁徙过度造成了贫油状况。在内部和中间位置，当转速为800 r/min时会出现较为明显的贫油状态，在边缘位置，转速为100、400和600 r/min会出现较为明显的贫油状态。这些研究结果为滚动轴承脂润滑的进一步研究奠定了基础。

关键词: 分布, 离心分离, 传质, 润滑脂, 灰分分析