Simulation and measurement of wear behaviour of round link chains

Interaction of chain and chain wheel is the central point of interest in a lifting process in chain hoists. The position of the chain links in the pockets of the wheel an their displacement relative to the wheel not only determine the degradiation of contact forces but also has a strong influence on the shape of equivalent (analoque) polygon which as a result of the “piecewhise straightness” of the chainlinks has an influence to the lifting speed and is therefore stimulating oscillations. Contrary to chainwheels that are used for mining purposes, chainwheels in chain hoists are supporting the vertical link, what has a positive effect to appearing stress caused by different degradiation of forces. This work is including a calculation-algorytm to allow quick and easy determination of forces under variation of essential parameters. Friction in contact points between the links and between chain and wheel have been considered as well as rolling and slipping effects of the chain links. The effects of those movements to the shape of the equivalent polygon have been analysed, based on a distinction of static and sliding friction. Within the scope of the work a universal test stand was designed and build, which allowes a wide range of experiments (wear observation, optmisation of the participated components, observation of resonance osscillations) with hoists under realistic circumstances.