1 introduction
Oil – gas lubrication system is developed on the basis of oil mist lubrication system. The oil and gas lubrication system is formed by the engineers of REBS Central Lubrication Technology Co., LTD. After measuring and distributing the oil, it is sent to specially designed oil and gas mixing blocks and then sent out through pipelines. With oil mist lubrication, lubrication system of oil and gas atomization device, the distribution of the lubricating oil by progressive distributor, lubricating oil and air mixing in the mixture of oil and gas, in the whole process of the distribution of the lubricating oil, mixing, there is no lubricating oil atomization, oil and gas two phase fluid through the phi 4 — 10 mm conveying pipeline to lubrication points, in the conveying pipe, Oil and gas two-phase fluid forms a stable annular flow. The characteristics of this annular flow pattern are as follows: Gas phase velocity is higher, the velocity of liquid phase is low, the general form full development in tube section, lubricating oil in the tube, evenly spread out in a row, in the form of oil film distribution on the tube wall, and tube center of high-speed flow to contain a small amount of oil droplets in the air, the circular flow of oil and gas can ensure every moment has lubricating oil to the lubrication, the gas phase velocity is relatively high, Can ensure a relatively high gas outlet flow rate, is conducive to heat transfer. A typical oil-gas lubrication system consists of compressor, lubricating oil pump, air volume flowmeter, conveying pipeline, oil-gas mixing block and so on. The air enters the oil-gas mixing block through the pressure regulating valve and volume flowmeter from the press, and the lubricating oil enters the oil-gas mixing block through the one-way valve from the electromagnetic metering pump. The oil supply is precisely adjusted by adjusting the oil supply time interval, and the lubricating oil and air are transferred from the oil-gas conveying pipe to the lubrication point.
- Inlet pipe 2. Valve 3. Precision filter pressure regulating valve 4. Air volume flowmeter 6. Oil and gas mixer 7. Electromagnetic pump 9. Tank 10. Oil and gas transfer pipe
2. Research status of oil and gas lubrication application abroad
Oil-gas lubrication has been successfully applied to rolling bearings, and foreign scholars have carried out a series of basic studies on the application of oil-gas lubrication to rolling bearings. The results show that, compared with traditional oil lubrication, oil-gas lubrication has the characteristics of obvious cooling and low oil consumption. Cheng-Hsien Wu et al. used the orthogonal test method to analyze the optimal parameter ratio for the temperature rise of rolling bearings by taking the oil supply amount per unit time, oil supply time interval, gas supply pressure, pipeline length and lubricating oil viscosity as the influencing factors. It is pointed out that oil supply per unit time, oil supply time interval and air supply pressure are the main factors affecting the temperature rise of oil-gas lubricated bearing. The research of K.Raesh et al. showed that when oil-gas lubrication was applied to rolling bearings, there was an oil film between the roller and the wall surface, and the thickness of the oil film was measured by capacitance method. It was believed that the cooling heat transfer of oil-gas lubrication on rolling bearings was mainly convective heat transfer.
3. Domestic research status of oil and gas lubrication
In China, oil-gas lubrication has been successfully applied in the lubrication and cooling of industrial rolling bearings, and gradually replaced the oil-oil lubrication mode. Various research institutions have also carried out the system optimization of oil-gas lubrication, influencing factors and auxiliary system related basic research. Many scholars have shown that when oil-gas lubrication is applied to rolling bearings, there is an optimal oil supply quantity, which makes the temperature rise of the bearing the lowest, and the temperature rise of rolling bearings changes with the viscosity of lubricating oil, bearing speed, air supply pressure, oil and gas supply position, and oil supply frequency. With the increase of oil supply, the bearing temperature shows a gradual change from large to small and then to large. As the viscosity index increases,
Bearing temperature rise also presents a change process from large to small, and then from small to large. The lubrication effect of oil-gas lubrication on rolling bearings is obviously better than that of pure oil lubrication. In a certain experimental condition, oil-gas lubrication can reduce the temperature rise of rolling bearings by 5℃ compared with the traditional continuous oil supply lubrication. The lubrication effect of oil-gas lubricated rolling bearing is directly related to the oil supply quantity. Under different conditions of speed and load, there are different optimal oil supply quantity. Working under the optimal oil supply quantity can make the temperature rise of each temperature measurement point the lowest and the lubrication effect the best. In addition to outside the cooling lubrication oil and gas has obvious advantage, in bearing life and bearing seal, lubrication oil and gas is also good to traditional oil lubrication, baotou steel # 5 continuous caster two cold chamber casting equipment original oil lubrication, fan-shaped section bearing use life to an average of 0.5 months, lubrication oil and gas sector after period of the service life of up to six months. Maanshan iron and steel co., LTD., 1400 m steel billet continuous casting machine design and manufacture for west heavy, all the original caster equipment bearing lubrication with centralized dry oil lubrication, the fan group section of the roller bearing life is only 1 ~ 2 months, up to 4 months, so had to replace the fan section often stop and offline take to repair the damaged rolls out, The annual expenditure for this is more than 10 million yuan, the use of oil and gas lubrication bearing within a year without damage.
4 conclusion
In conclusion, oil and gas lubrication has the following advantages compared with traditional oil lubrication when applied to rolling bearings:
(1) Low lubricating oil consumption, saving lubricant dosage;
(2) the bearing temperature rise is lower than the traditional oil lubrication, and the bearing life is improved;
(3) Centralized lubrication system is conducive to management and maintenance, the use of PLC accurate control of oil supply, gas supply, high degree of automation.
Although oil-gas lubrication has been successfully applied in rolling bearings, there are still many problems to be explored and solved, mainly reflected in:
(1) The oil-gas lubrication and cooling mechanism is not clear, and the bearing mechanism of the internal fluid film is not clear;
(2) There is no unified standard for the proportion-selection relationship of oil supply and air supply of different bearings;
(3) Since the oil-gas lubrication system must be equipped with a pneumatic source when it is applied to rolling bearings, this limits the application of oil-gas lubrication system to gas turbines, aviation and other fields to some extent;
(4) Oil and gas lubrication is in a blank stage in the application of ceramic bearings and other materials rolling bearings.
Oil-gas lubrication for rolling bearings has many advantages over traditional lubrication, but oil-gas lubrication needs further research and continuous exploration in many aspects and a wide range of applications.
