| Résumé : |
In the early mechanical operations much of the focus is on cutting, and for optimum effect the skins must be held flat against the cutting blade or knife. This requires a stretching action for good presentation, which is mainly provided within fleshing and shaving operations by spiral cutting blades on the rotating cylinder. In the splitting operations this is achieved by the helically-grooved gauge roller, and, in part, by the movement of the knife blade, as well as in presentation to the samm/setting operation by the setting cylinder.
Over and above the objective of the operation, stretch is involved at the point of contact between the hide and blade. This action can be considerable, and the physical properties of the skin at that time—especially the ease and degree of extendibility, compression and recovery—strongly affect the outcome of the operation.
Adjustments are made, both to machine settings and presentation, to achieve the best balance of results. But success is a balance between the way force is applied by the machine and received by the skin. It is an equal partnership, but however sophisticated the machine or perfect the application, variations still occur.
The following diagrams provide an insight into the behaviour of mechanically-stressed pieces dependent upon skin condition. Over and above inherent skin variations, as hides and skins progress within manufacture the permutations that generate change increase enormously. |
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Ajouter le résultat dans votre panier Affiner la rechercheThe behaviour of pieces in machine operations as a function of temperature and moisture content in WORLD LEATHER, Vol. 18, N° 8 (12/2005 - 01/2006)
