UBC Theses and Dissertations
The effect of bandsaw stresses of blade stiffness and cutting accuracy Taylor, John
This thesis consists of an experimentally based study of the effect of bandsaw stresses on blade stiffness and cutting accuracy for the bandmills used for primary breakdown in North American sawmills. The effect of bandsaw roll-tensioning and bandmill axial forces on the stresses in the blade, on the interaction of the blade with the bandmill and on the stiffness and cutting accuracy of the sawblade are examined. The stresses due to roll-tensioning are measured and empirical relationships developed that relate the rolling load to the stresses induced. Investigations into effect of roll-tensioning on the torsional frequency and lateral stiffness of the sawblade show that rolling in the centre 60% of the sawblade will increase blade stiffness while rolling outside this region will decrease it. The optimum rolling location was shown to be the sawblade centre-line. The stresses in the blade due to the interaction of the blade and wheel were analyzed and a model was developed that successfully predicted the effects of roll-tensioning and overhang on the tracking stability of the sawblade. Experiments were conducted to determine how the stresses, frequency and stiffness of the sawblade relate to its cutting accuracy. The experiments indicate that cutting accuracy is strongly related to the lateral edge stiffness of the sawblade and that improved cutting accuracy can be obtained by confining the roll-tensioning to be close to the blade centre-line.
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