In is of threaded in nature and the

In wind turbines, a large number of main shafts are supported in spherical roller bearing that is mounted directly on the bedplate and these bearings have to be locked securely. In general, the connection between the bearing inner ring and the shaft is consisting of interference fit; however, there are more chances of slippage under high load conditions. So, lock nut helps to precise and axial fixation of bearing on the shaft. According to the provided data, the standard lock nut has been used which is of threaded in nature and the aim is to change the existing lock nut. In order to improve the design and effectiveness of locking, the best possible way would be a keyless lock nut/ keyless bushing and it has indisputable advantages compared to thread lock nut. The keyless lock nut is also known as shrink disc and it works based on interference fit technique.An interference fit is a pre-stresses mechanism of joining a shaft and a hub and can transfer torque, force or combination of both through the formation of large radial pressure at the interface of its mating surface. It has structural advantages of being rigid, effective, and compact cite{biron2013optimal, truman2007analysis}. An interference fit has the great load-bearing capacity and excellent aligning performance under complex load conditions. The working principle involves creating a pressure between the inside diameter of the inner ring and the outside diameter of the shaft through the interference in dimension between the inner ring and outer ring radial interface.nterference fit needs to be designed and produced by adopting some standards in order to obtain the expected functionality, especially with the following standards:Interference: The ISO standardsĀ  and/or design guidelinesĀ  is required in order to obtain the best possible interference between the inner diameter of the inner ring and the outer diameter of the shaft for a provided nominal dimension and generated radial pressure at the mating surface.Component dimension: very precise dimension or least possible dimensional deviation of the component parts is mandatory.Surface finish: A small deviation in surface finish could create a huge contact pressure deviation. Surface finish values need to be range from 0.4 to 1.6 $mu$m rad in order to gain sufficient frictional adhesion at the mating surface .Stress concentration: These are generated in the shrink disc and shaft because of the abrupt sudden transition between uncompressed to compressed material.Working stress: The generated stresses due to interference fit pressure and additional stresses should not be more than the strength of the material.Fretting: It occurs due to rubbing of mechanical parts at the contacting surfaces. An interference fit assembly carries axial force and/or torque by creating the radial pressure between mating surfaces, so fretting could occur if the interference pressure is not adequate to restrict the relative motion/slip between the inner ring and the shaft. Based on the magnitude of slip, both fatigue and fretting wear can cause a premature damage.


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