For bearings, the definition of environment mainly includes the following:
- Matching of bearing shaft and seat hole
- Working temperature of the bearing
- Cleanliness of the working environment of bearings
- Bearing stress (also known as the load spectrum)
- Lubrication of bearings
The subtle difference of each of these items will have a "great" impact on the actual service life of bearings, which is very great.For example, the cleanliness of the working environment can be multiplied by a coefficient of L10 life based on the severity of pollution. The coefficient ranges from 0.1 to 20, and the specific value depends on experience. In other words, people with different values may differ greatly.The life of bearings is divided into calculated life and actual life.For calculating life spans, we generally call this process "fortune-telling."According to the project encountered, summed up a general rule, the accuracy is almost 50%, that is to say, the calculated life is 10,000 hours, the actual life should be between 5,000 and 15,000 hours.Please note that this is the result of various correction coefficients calculated by the special software of the world's second bearing plant.Domestic manufacturers, I have also made a comparison, if the software calculation, basically calculate the life divided by 20, is about this order of magnitude.
The simplest way to think about the actual life, the service life, is to do experiments.The relatively common practice in the automobile industry is to run bench test and vehicle test.Just put your bearings on the assembly and run, and whatever comes out is what comes out.There must be a paragraph at the end of the bearing life calculation report that the calculation report is for reference only and the actual results are subject to the experiment.There are too many influencing factors, and the selection of bearings is a process of compromise.For example, clearance is generally greater than 0, in order to make the starting torque and lubrication better, but in the machine tool spindle and high-precision rotary platform, clearance is negative, for the purpose of running accuracy.
There are different considerations from the design of this is also some, SKF bearings and NSK bearings are different in the selection of steel and actual steel, whether it is national or international standards, basically are the lowest grade of steel used in the bearing, in fact, large bearing plants will sign special supply agreements with steel mills.Scientific explanation, I personally think bearing this thing is difficult to use a simple theory to explain.Bearing is not a component, it is a system.The so-called system, bearing suppliers are to carry out design check.Even with standard bearings, also need to be checked.
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