Abstract
On the lubrication of fibre or yarn with liquid lubricant, the frictional force as a function of the sliding speed and the lubricant viscosity has been studied.
1) When a fibre or yarn slides around a cylinder under hydrodynamic lubrication, the relation between the tensions and the sliding speed may be expressed thus: where T: final tension of the fibre or yarn sliding around a cylinder, T0: initial tension of the fibre or yarn, N: constant (frictional index), k: constant, U: sliding speed of the fibre or yarn against the cylinder. On the above equation, log (T1-N-T01-N) has the gradient (1-N) with respect to log U. Applying this character, it is able to test either the lubrication is hydrodynamic or not.
2) When the sliding speed and the lubricant visocsity are extremely lower or higher, the lubrication is not hydrodynamic.
3) A model for the lubrication of fibre or yarn with liquid lubricant was made.
4) Applying the experimental result of the lubrication for crossing metallic cylinders, the thickness of the lubricant film between the asperity of fibre and a sliding body was estimated. From this thickness it has been found that the hydrodynamic lubrication may exist in popular processing of fibre.
