| 摘要 |
Apparatus for opening and uncurling sheet or web material, and for guiding the material along a given path, includes first and second pairs of rotatable selvage uncurlers arranged in serial order. The uncurlers of each pair engage opposite edges of the material. The lateral pull exerted by each uncurler is controlled by position sensors at either edge of the material. These are connected to react to an outward lateral shift of a first edge of the sheet by reducing the lateral pull applied to it by one of the first pair of uncurlers, and also by increasing the lateral pull on the other edge of the sheet by one of the second pair of uncurlers. This causes an inward lateral shift of the first edge that produces opposite results, increasing the pull of the first-mentioned uncurler and decreasing the pull of the second. The two remaining uncurlers are similarly affected by lateral shifts of the second edge of the material. The apparatus guides the material with a quickly responsive continuous hunting action, while opening and uncurling the material into a flat form.
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