国产大型立式减速机润滑系统的改进建议

2020-09-08

Wang Jianqiang and Chen Hao (Suzhou Sinoma Construction Co., Ltd.)Preface With the rapid development of domestic manufacturing industry, domestic large-scale vertical reducer is also widely used in various industries. As the heart equipment of factories and mines, large vertical reducer plays a key role in the production efficiency of enterprises. In recent years, it is found that the failure rate of domestic large reducer is significantly higher than that of imported equipment of the same type. The common faults of domestic large-scale vertical reducer are: input shaft bearing overheated and burned, input shaft spiral bevel gear broken shaft, spiral bevel gear tooth broken, thrust pad overheated burning and so on. One of the most common faults is the input shaft bearing overheated burning, broken shaft, broken teeth, after analysis, most of the causes of reducer failure are due to poor lubrication and heat dissipation of the lubrication system. 1. Failure cause analysis (1) The blockage of lubricating oil way will reduce the oil supply and accelerate the wear of bearings and other parts. In the daily use and maintenance, the filter is often blocked and the filter is not cleaned in time, which leads to the decrease of oil supply, insufficient lubrication of the input shaft bearing, long-term heating and wear of the bearing, and even the bearing damage and bearing scattering. (2) Impurities in the lubricating oil enter into the reducer, causing wear of bearing and tooth surface. In the process of cleaning the filter, the improper operation of the workers caused the pollution of lubricating oil, or the negligence in the process of assembling the filter caused foreign matters to enter the reducer, resulting in bearing or gear damage. (3) If the temperature of lubricating oil is too high, the viscosity of lubricating oil will be reduced, the oil film will be damaged, the bearing will be worn and the tooth surface will be pitted. The wear of bearing parts causes the bearing clearance to become larger, which makes the runout of the input shaft of the reducer larger. The input shaft teeth knock on the secondary teeth, and the stress surface of the tooth surface changes, resulting in bearing damage, shaft fracture and tooth fracture. 2 improvement measures In view of the above problems in the use of the lubricating oil station, the following improvements are recommended. (1) Cancel the oil tank of lubricating oil station and store the lubricating oil in the bearing box and gear box of thrust pad of reducer. If all the lubricating oil is stored in the oil tank of the oil station, when the lubricating oil station fails and stops, although the main power generator will be cut off and shut down, the inertia of the motor will continue to run the reducer for several cycles. At this time, there will be no lubricating oil in the reducer to lubricate all parts, causing damage to the thrust pad, bearing and teeth in the reducer; the lubricating oil will be stored in the thrust pad bearing box and gear of the reducer In this way, not only the space occupied by the lubricating oil station can be saved, but also the lubricating oil stored in the thrust pad bearing box and gear box can be stored in the thrust pad bearing box and gear box during the period of inertia operation when the lubricating oil station fails to stop, and the thrust pad, bearing and teeth in the reducer will not be damaged. At the same time, the lubricating oil stored in the reducer can well cool the internal temperature of the reducer. (2) The two groups of diaphragm filters in lubricating oil station were changed into a set of metal mesh composite filter element with filtration precision of & le; 25 & mu; M. At present, most of the lubricating oil station filters for domestic large-scale vertical reducer are two groups of diaphragm filters. The lubricating oil of reducer gear and bearing enters the reducer through the coarse filter (filtration accuracy, & le; 120 & mu; m); the high-pressure oil passes through the fine filter (filtration accuracy & le; 40 & mu; m); m) Entering into the thrust bearing bush of the reducer, this configuration is easy to make small metal particles enter the reducer, causing pitting corrosion on the tooth surface and bearing damage; moreover, it is necessary to manually clean the filter diaphragm, which is easy to cause foreign matters into the lubricating oil and damage the reducer during the cleaning process. Therefore, it is suggested that only one group (two filters, one for use and one for standby) should be used at the outlet of the oil pump in the oil station, and the filtration precision is & le; 25 & mu; m metal mesh composite filter element, and the lubricating oil passing through the filter enters into the reducer through high and low pressure pipes. The accuracy of the filter has been improved. Attention should be paid to increasing the filtering area of the filter to ensure the normal operation of the pressure difference before and after the filter. When the pressure difference is higher than 0.2MPa, switch to the standby filter and replace with a new filter element. This not only improves the filtering level of lubricating oil, but also reduces the pollution of lubricating oil caused by manual errors in the process of cleaning the filter. The use of metal mesh composite filter with filtering precision of & le; 25 & mu; m can provide high clean lubricating oil for the reducer, reduce the wear of bearing and tooth surface, and improve the service life of the reducer. (3) When the flow rate is lower than 85% of the rated flow, the reducer motor stops running. In this way, the change of oil quantity entering the reducer can be monitored at any time, so as to avoid the reduction of lubricating oil quantity caused by the failure of lubricating oil station for a long time, resulting in high temperature of reducer bearing and wear of tooth surface. (4) A filter and a flowmeter are installed in the water inlet pipe of the heat exchanger. The inlet pipe of heat exchanger in lubricating oil station is easy to be blocked by foreign matters, and the electromagnetic on-off valve controlling cooling water is also easy to fail to open, resulting in insufficient water supply and no cooling of oil temperature. The flow rate of water can be seen directly by adding a flowmeter. When the water flow rate decreases, the impurities in the filter can be found and removed in time to ensure that the lubricating oil temperature is between 25 ℃ and 60 ℃. It will not cause the failure of lubricating oil film due to high oil temperature, which will cause the wear of bearing and tooth surface. ConclusionThe quality of the lubrication system directly affects the operation rate and service life of the large reducer. Through the above improvements, it can effectively avoid the wear of the reducer bearing and tooth surface caused by the insufficient oil supply of the lubricating oil station and the high temperature of the lubricating oil, as well as the damage caused by the foreign matters entering the reducer due to the manual cleaning of the filter. It is more important to store the lubricating oil in the reducer, which can not only reduce the space of the lubricating oil station, but also reduce the internal temperature of the reducer. It can also protect the reducer from damage under the condition of short-term oil cut-off. It is recommended that this scheme be adopted for large-scale reducer with lubricating oil station lubrication. Finally, the purpose of improving the operation rate and service life of domestic equipment is achieved.Source: cement engineering, issue 04, 2019

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