Views:68 Author:Site Editor Publish Time: 2019-04-18 Origin:Site
First, the status quo of the bearing “running circle” problem
The so-called bearing “running circle” is that the outer ring of the bearing and the bearing seat or the inner ring and the shaft have a relative movement. The planetary gear of the gearbox has a running ring that will cause irreparable damage to the gearbox.
Since the beginning of 2015, the running wind turbines have gradually exposed the problem of gearbox bearings “running circles”. According to incomplete statistics, in recent years, more than 100,000 units installed in China have suffered from “bearing running circle” failures, accounting for more than 10%. Not only are the double-fed motor units with more bearing applications, but also the main drive system bearings. Similar failures occurred in fewer direct-drive units, and the total number exceeded 1,000. According to a team of power equipment research institutes who recently measured the results of a group of operating units, the vibration spectrum showed a fairly high percentage of the unit’s running problems (according to what they say is almost 100%). Some units of foreign manufacturers also have bearing running problems. From the overall situation of the found bearing “running circle”, the high-speed end of the gearbox has a higher proportion, and the proportion of the planetary gear bearing “running circle” is lower. However, in the products of several manufacturers, the proportion of “running circles” of planetary gear bearings is relatively high, and batch failures occur.
The loss caused by the bearing running circle will greatly increase the operation and maintenance cost of the wind turbine, and may also affect the insurance company’s premium rate in the future.
At present, most of the domestic manufacturers, developers, and insurance companies that have bearing running circles do not understand this situation. The faults are handled by the gearbox factory itself, and the customer’s transmission is not truthfully told. In this case, this high-risk, high-cost failure has become a huge potential risk in the wind power operation and insurance industry.
Most of the handling of the “running circle” failure of the high-speed end bearing of the gearbox is solved by inserting or using a polymer binder after the fault is discovered. These two methods have relatively mature experience in ground equipment, but for the high-speed end bearing of the wind turbine gearbox, whether it can guarantee long-term use after repair, there is no mature experience.
For the planetary gear bearing “running circle”, there is no mature technology that finds the “running circle” fault in advance in China, and the difference in the spectrum of the bearing “running circle” due to the difference between the unit form and the operating environment, so most planetary gears Bearing “running” failure is confirmed after the transmission is damaged.
For the main bearing running ring of the direct drive unit, if no obvious damage is found in the bearing, the method of adjusting the bearing clearance is adopted; if the bearing is damaged, the main bearing is replaced.
Second, the analysis of the problem of bearing “running circle”
It is fundamentally due to improper bearing selection, improper structural design and load design, improper process control during manufacturing, improper adjustment of bearing clearance, improper bearing lubrication, improper storage or transportation of equipment, etc., resulting in bearing roller and bearing raceway. Severe sliding semi-dry friction occurs, eventually leading to the bearing “running circle”.