Web tensioning device with improved excursion control

Abstract

A web tensioning device utilizes a dancer device, either angular or linear, which can be positioned by a controlled servo motor. In a preferred embodiment, the controller for the servo motor receives an input signal based on the acceleration (positive or negative) of the dancer device caused by a web excursion and implements a compensation necessary to oppose the web excursion. The controller may also receive additional input signals indicative of the acceleration of the web itself, resulting from the web excursion.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is a continuation-in-part of U.S. patent application Ser. No. 10 / 717,019 filed Nov. 19, 2003, now U.S. Pat. No. 7,438,251, which, in turn, is a continuation-in-part of U.S. patent application Ser. No. 10 / 465,219 filed Jun. 19, 2003, now abandoned, the disclosures of which are fully incorporated herein.FIELD OF INVENTION[0002]This invention relates to devices for tensioning webs, such as paper webs or textile webs, during processing. More particularly, this invention relates to ongoing dynamic control of excursions of web tensionBACKGROUND OF THE INVENTION[0003]Web tension control is important in paper conversion processes and the like. In high speed operations, even relatively small web excursions such as variations in web tension may cause web processing difficulties downstream. Moreover, in relatively high speed web lines, such as those exceeding about 500 feet per minute (about 150 meters per minute), manual adjustment ...

AI Technical Summary

Benefits of technology

[0005]In one aspect, the present invention provides a novel and an improved web tensioning device that minimizes the disadvantages associated with the prior art devices and provides advantages in construction, mode of operation and use.

Problems solved by technology

In high speed operations, even relatively small web excursions such as variations in web tension may cause web processing difficulties downstream.

Moreover, in relatively high speed web lines, such as those exceeding about 500 feet per minute (about 150 meters per minute), manual adjustment of web tension is not practical.

In web tensioning systems where web tension is controlled or maintained by a dancer, a limitation on effective control of web tension is the response time of the dancer inasmuch as often the dancer movement lags behind the actual changes in web tension.

A primary cause of such relatively long response time is the weight of the dancer.

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