| 摘要 |
Disclosed herein is a method and apparatus for forming a sheet of extruded deformable polymer with a plurality of longitudinally extending fracture lines along which splitting can occur to sub-divide the sheet into a plurality of filaments or tapes. The apparatus includes an elongated embossing roll having circumferential ridges formed on the periphery thereof with a cooperable backing roll positioned to press the sheet into engagement with the embossing roll so that the ridges and intervening grooves of the embossing roll are formed in the hot plastic sheet. The zone between the backing roll and embossing roll constitutes a first nip zone. A pressure roll is disposed adjacent to the embossing roll with a second nip zone being defined between these two rolls. The pressure roll is spaced downstream from the backing roll, having reference to the direction of movement of the sheet, a distance sufficient to permit the outer surfaces of the hot sheet to cool and set but to permit the center region between the surfaces to remain plastic. Thus, the hot sheet which has been embossed at the first nip zone is reformed at the second nip zone with the embossments from the embossing roll thereby correcting for any distortion in the original embossments which occur as the sheet begins to cool. Consequently, the final product is a sheet having highly accurate embossments therein. The cooperative effect of the first and second nip zones also acts to retain the sheet against the embossing roll as the sheet moves from the first nip zone to the second nip zone. Means are provided for adjusting the pressure which the pressure roll exerts to force the sheet into engagement with the embossing roll.
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