Estimation of service life of adapter sleeve by standard life calculation method
The fatigue life of the fastening sleeve 1, the basic concept of the fatigue life of the fastening sleeve in the general sense of the fatigue life is a certain technical state (structure, process state, fit, installation, clearance and lubrication state, etc.) of the fastening sleeve, in the actual use of the host state of operation, until the rolling surface fatigue and can not meet the requirements of the host, the total value of the number of relative rotations of the fastening sleeve inner and outer ring (shaft, seat ring) --Total number of revolutions. When the tightening sleeve rotation more or less constant or known, fatigue life available with the total number of revolutions corresponding to the total number of hours of operation to express, in addition, it should be noted that: 1, the impact of tightening sleeve fatigue life of very many factors, can not all be estimated or eliminated through the standard test conditions, which caused the actual fatigue life of the tightening sleeve has a great deal of dispersion, so the tightening sleeve fatigue life of the expression parameters for the rated life L10, In ISO recommended standard R281, the meaning of L10 is clearly defined as follows: "The rated life L10 of a batch of the same tightening bush in sufficient quantity is expressed in revolutions (or hours when the speed is constant), and 90% of the batch of tightening bush can reach or exceed this number of revolutions (or hours) before fatigue spalling occurs".
So far, all countries in the world follow the above regulations.
In some countries such as the United States, the concept of median life is also used.
The median life LM is the median life of a batch of the same fastening sleeve, that is, 50% of which can reach or exceed the total number of revolutions before fatigue stripping, or the number of hours of work at a certain speed, the median life LM is not the arithmetic average of the life of a batch of fastening sleeve.
Generally, the median life LM is about 5 times of the rated life.2. The concept of rated life is only applicable to a sufficient number of tightening sets, but not to individual tightening sets.
For example, there are 40 sets of 6204 clamping sleeve according to its use of the article to calculate its rated life of 1000h without fatigue damage, the remaining 4 sets may be less than 1000h that fatigue failure of the clamping sleeve, the meaning of the rated fatigue life on behalf of this batch of clamping sleeve in the normal play of its material potential can be expected life.
Therefore, in most cases, the user in the selection of the tightening set still first fatigue life calculation, and then according to the actual failure category for verification, such as wear life verification, take the smaller value of the calculation results for the tightening set of calculated life. Second, the fatigue life of the tightening set of the estimated method of fatigue life of the tightening set of the estimated method of calculation and test Zhan branch two. According to the prescribed formula and calculation rules calculated by the fatigue life of the fastening set as the calculated fatigue life, the total value of the calculated rotation for the inner ring or shaft ring rotation (when the outer ring or seat ring is fixed) when the total value of rotation.
According to our standard test method (ZQ 12-94) fatigue life test procedure for tightening sleeve), in the use of performance to meet the requirements of a method of testing machine, a batch of tightening sleeve for sampling fatigue life test, the actual test life from the test data processing, that is, the fatigue test life of the batch of tightening sleeve represented by the test tightening sleeve. The fatigue life test of the fastening sleeve is an enhanced fatigue life test method in which the wear factor of the fastening sleeve is suppressed to the maximum extent by adequate lubrication and the fatigue factor of the fastening sleeve is highlighted by the enhanced load and speed. The fatigue life calculation method and the fatigue life test are complementary to each other, and the results obtained from both have sufficient correspondence.
In fact, it is economically, time- and labor-intensive to take a sufficient number of fastening sleeves for life testing to verify the suitability of the selected sleeve for each specific application, so the test method of fastening sleeve life is only used in very necessary or important cases. In the vast majority of cases, the standard life calculation method is used to estimate the service life of the clamping sleeve, with a sufficient degree of dependability.
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