Winding – tensioning – or guiding – Convolute winding of material – Detector – control – or material responsive stop
Reexamination Certificate
1999-05-12
2001-04-03
Matecki, Katherine A. (Department: 3653)
Winding, tensioning, or guiding
Convolute winding of material
Detector, control, or material responsive stop
C242S541100, C242S413900, C242S413000
Reexamination Certificate
active
06209817
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. § 119 of German Patent Application No. 198 21 318.2, filed on May 13, 1998, the disclosure of which is expressly incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is directed to a method and apparatus for monitoring a winding hardness of a material web wound onto a winding roll.
2. Discussion of Background Information
The present invention will be described below with respect to a material web, such as, for example, a paper web. However, it is understood that the invention is equally applicable to other types of web material without departing from the spirit and/or scope of the invention.
During an operation to produce a material web, such as, for example, paper web, the paper web is typically wound into saleable rolls, referred to as winding rolls. Generally, the paper web is wound onto a core, such as, for example, a cardboard tube. During this operation, it is desirable to achieve a winding hardness pattern in which the winding hardness decreases from a center to an outside.
Factors that influence a winding hardness include, but are not limited to, for example, a pressure with which the paper web is pressed against the winding roll, when the paper web encounters the winding roll, and a tensile stress wound into the paper web. In this regard, it is noted that the tensile stress can be changed (varied) by, for example, changing a driving torque (e.g., increasing or decreasing the driving torque) of an associated winding motor that forms the winding roll. In a king roll winder, in which the winding roll lies in a winding bed formed by a plurality of king rolls, a wound-in tensile stress can be changed by operating one drum winder, of a plurality of drum winders, at a speed (or torque) that differs from the speed (or torque) of the remaining drum winders.
Experience with winding rolls has yielded values that can be used to influence the winding hardness in a desired direction. However, it is very difficult to actually determine the winding hardness during a winding operation.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to develop an apparatus and method for monitoring a winding hardness of a material web wound onto a winding roll during a winding operation.
In the current invention, the term “stretch” refers to a change in length of a section of a paper web (or other web material) that is observable when a tensile force is applied to the material web. Most material webs can be stretched to a certain degree before they tear. The maximum amount the material may be stretched is dependent on the tensile stress of the section of the paper web to be stretched. The amount of stretch to which a paper web can be subjected is relatively small. However, if the properties of the paper web has been previously determined, the amount of stretch can be used as a reliable indication of the tensile stress to which the paper web is subjected. If one monitors the stretch on a continuous basis (or at predetermined discrete intervals), continuous (or quasi-continuous) information is obtained on the tensile stress to which the paper web is subjected during the winding operation. Thus, very reliable conclusions regarding the winding hardness of the material web roll can be reached.
It is especially advantageous if the change in the material web's length is determined between two measurement points having different tensile stresses. In the current application, the phrase “measurement point” is defined as a location where information is available on the length of a section of the material web. The amount of stretch of a section of material web is not monitored continuously, but rather, is based upon two measurements (or determinations of length). Typically, one measurement is made prior to the application of the tensile force, while the second measurement is made after the application of the tensile force (or, alternatively, after the tensile force has been raised). This reduces the measurement work. If such measurements (or determinations) are performed for several sections of the material web, information on the tensile stress of the web material is obtained with a desired continuity.
Preferably, the measurement points are separated from one another by a nip. A nip (or gap) between rolls leads to a decoupling of the tensile stress in the material web ahead of and behind the nip. As a result, the two states of the material web can be reliably separated from one another.
It is advantageous for the nip to be formed between the winding roll and a king roll. Then, it is not necessary to use any additional structural members to create the nip. This nip is available in any case and can be used for carrying out the measurement.
It is generally not practical to employ a physical contact device (e.g., a measuring device that contacts the paper web) to measure the stretch of the paper web during the winding operation. However, an optical measurement device can be used to measure the stretch of the paper web without physically contacting the paper web. Moreover, optical measurement devices are capable of measuring even relatively small changes (i.e. relatively small stretch in the material web).
In the preferred embodiment, the material web is provided with markings at predetermined spacings (or lengths). The markings facilitate the optical measurement of the stretch. The markings are detected (in the instant invention) using an appropriate measuring sensor. The markings are applied prior to the application of the tensile stress (or, at a location where a first tensile stress prevails). Then, when the tensile stress is applied (or changed), the markings stretch with the material web, so that the spacing between markings increase. By determining the spacing of the markings (or their length), one obtains information on the change in length, or stretch, of the material web with the change in tensile stress. One must then only ensure that the material web is actually wound with respect to the measured tensile stress.
The present invention discloses an apparatus and method that easily measures an amount of stretch at a section of the material web that rests on the winding roll. It is noted that the tensile stress can no longer change in this location. Furthermore, the measured tensile stress directly affects the winding hardness, so that the information on the tensile stress suffices to determine the course of the winding hardness.
After the amount of stretch has been determined, it is no longer necessary for the markings to remain on the surface of the material web. Accordingly, it is desirable that the markings disappear after the measurement is made. That is, it is desirable to use a marking material, such as, for example, an ink, that disappears after the passage of a predetermined time period, so as not to disfigure the appearance of the material web.
Thus, in the instant invention, the markings are created on the material web by applying an ink that turns invisible after a finite period of time. Such inks are known, for example, in the joke industry as “disappearing ink”. Similar type inks are used by children and is called “magic ink”. One such manufacturer of such inks in The Walter Toufar Gesellschaft, located at Herzgasse 39-41, A-1100 Vienna, Austria. This company produces various disappearing inks having different color intensities. In the preferred embodiment, the color intensity of the ink is selected based upon the optical sensitivity characteristics of the employed optical sensor. A shift in pH causes the ink to become, after the lapse of the finite period of time, a pure aqueous solution that evaporates. As a result, the ink does not contaminate the material web. In this regard, it is noted that the moisture of the ink placed on the material web does not adversely affect the quality/characteristics of the material web prior to its evaporation.
In the preferred embodiment, the ink evaporates and disappea
Conrad Hans-Rolf
Cramer Dirk
Greenblum & Bernstein P.L.C.
Matecki Katherine A.
Voith Sulzer Papiertechnik Patent GmbH
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