Zoned stretching of a web
First Claim
1. A method of orienting a web in a cross machine direction comprising, providing an anisotropic web having a width dimension and a substantially continuous length dimension, the web having a strength in the length dimension greater than in the width dimension placing the web along a downweb web path under tension less than that needed to elongate the web in the downweb direction, moving a section of the web in the width dimension out of the web path with an orientation unit having a diversion device, while maintaining the web under tension along the downweb web path, so that at least a section of the web is elongated in the width dimension.
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Accused Products
Abstract
An apparatus and methods for stretching one or more zones of an anisotropic web and anisotropic webs including one or more stretched zones is provided. Each of the stretched zones in the web is stretched in the cross-web direction, i.e., the direction transverse to the down-web direction. The stretching can be performed continuously as the web is advancing through the apparatus in the down-web direction. The method for stretching an extensible web in the cross direction generally is practiced on a substantially continuous, extensible anisotropic web. The cross web stretching occurs in an orientation zone established by an orientation unit. The orientation unit moves the web out of the plane of the web where the web is under tension, but without any side restraints. The web moves over the orientation unit where the degree of orientation is proportional to the cross direction displacement of a portion of the web by the orientation unit. The anisotropic web has a tensile strength in the downweb direction greater than the cross direction such that the web is preferentially displaced in the cross web direction by the orientation unit. This can be a downweb direction tensile strength at least 50 percent greater than the cross web direction.
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Citations
29 Claims
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1. A method of orienting a web in a cross machine direction comprising, providing an anisotropic web having a width dimension and a substantially continuous length dimension, the web having a strength in the length dimension greater than in the width dimension
placing the web along a downweb web path under tension less than that needed to elongate the web in the downweb direction, moving a section of the web in the width dimension out of the web path with an orientation unit having a diversion device, while maintaining the web under tension along the downweb web path, so that at least a section of the web is elongated in the width dimension.
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19. An apparatus for orienting a web in a cross machine direction the apparatus comprising,
a web path having width dimension and a tensioning device in the downweb direction, and an orientation unit on a portion of the web path having a diversion device for diverting a web out of the web path wherein there are no restraining devices for holding down opposing sections of the web on either side of the orientation unit.
Specification