Dynamical analysis of rotary tiller: Stress on chain tightener.
1993
Iwasaki K. | Miyabe Y. | Kashiwagi S.
As the first step to establish a designing theory for a rotary tiller especially for the transmission system, the chain-sprocket and the tightener system were analyzed geometrically and the stress-measurement of the tightener was carried out. The obtained results are as follows: (1) With the geometrical analyses of the chain-sprocket system, and of the chain length calculated by chain pitch times the number of chain links was about 0.1% longer than the minimum length calculated geometrically with polygon figure. Even in this case, the displacement of the tightener top was calculated to be 13.97 mm. (2) With the wearing of chain parts, the total length of the chain may be elongated and at 1.5% elongation, the displacement of the top of the tightener should be 53.11 mm. Such a large displacement means quite a hard stress condition for the tightener. (3) By the measurement of the stress on the tightener, the magnitude of the stress at the top of the tightener was 70.9 kg./square mm at the installation to the chain-sprocket system, and the additional stress 7.9 kg/square mm acted on it with free rotation of the rotary shaft. (4) The measured stress curve seemed to be composed of the two different frequency curves. The short cycled curve was around 45 Hz and this value was very close to the number of clutching per second in case of the chain and the sprocket. The large cycled curve was around 2.5 Hz and this value was very close to the rotational speed of the rotary shaft. This means that the stress on the tightener is influenced both by the clutching of the chain and the sprocket and by the mass unbalance of the rotary shaft.
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