Method to measure tension in a moving web and to control properties of the web

Abstract

A process for determining the tension in a moving web is provided. The process includes the step of providing a web that is moving at a determined speed. The speed has a determined basis weight. A wave is created in the moving web. The speed of the propagation of the wave is determined. Also, the tension on the moving web is determined through a mathematical relationship between the wave speed, the basis weight of the web, and the speed of the web. The instability index of the web is greater than or equal to 0.5.

Description

BACKGROUND Products made from base webs such as bath tissues, facial tissues, paper towels, industrial wipers, food service wipers, napkins, medical pads, and other similar products are designed to include several important properties. For example, the products should have a soft feel and, for most applications, should be highly absorbent. The products should also have good stretch characteristics and should resist tearing. Further, the products should also have good strength characteristics, should be abrasion resistant, and should not deteriorate in the environment in which they are used. In the past, many attempts have been made to enhance and increase certain physical properties of such products. Unfortunately, when steps are taken to increase one property of these products, other characteristics of the products may be adversely affected. For instance, the softness of non-woven products, such as various paper products, can be increased by several different methods such as by s...

AI Technical Summary

Benefits of technology

Another exemplary embodiment of the present invention includes a process for producing a paper web that has at least two flows of different strengths. The process includes the step of providing a moving layered paper web, and providing at least one hardwood flow and at least one softwood flow. These flows form at least one hardwood layer and at least one softwood layer of the paper web. The tension on the paper web is determined while the web is moving. The tension of the paper web is controlled by increasing the hardwood flow and decreasing the softwood flow in regions of high tension, maintaining a uniform basis weight. Further, softwood flow is increased and hardwood decreased in regions of low tension so that the tension is uniform, maintaining a uniform basis weight.

Problems solved by technology

Unfortunately, when steps are taken to increase one property of these products, other characteristics of the products may be adversely affected.

Increasing softness according to one of the above methods, however, may adversely affect the strength of the product.

Conversely, steps normally taken to increase the strength of a fibrous web typically have an adverse impact upon the softness, the stiffness, or the absorbency of the web.

Current machines do not disclose a way of measuring the tension on a moving web when the instability index of the web is greater than 0.5.

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