Paper making and fiber liberation – Processes and products – With measuring – inspecting and/or testing
Reexamination Certificate
1999-09-29
2001-07-03
Nguyen, Dean T. (Department: 1731)
Paper making and fiber liberation
Processes and products
With measuring, inspecting and/or testing
C162S050000, C162S263000, C162SDIG006, C250S339030, C250S341300
Reexamination Certificate
active
06254726
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. § 119 of German Patent Application No. 198 44 927.5, filed on Sep. 30, 1998, the disclosure of which is expressly incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a measuring system for determining the moisture content of a fibrous web, e.g., a paper or textile web, in a machine for producing and/or processing the fibrous web. The moisture content is determined in a region of the machine in which the fibrous web runs without a free draw, i.e., is supported.
2. Discussion of Background Information
Prior art measuring systems allow the measurement of the moisture content generally only in long, free draws of the fibrous web (i.e., where the web is unsupported). However, due to increasing production speeds, guiding the fibrous web in as closed, i.e., supported, a manner as possible is becoming increasingly important.
A process is known, e.g., from German Patent Application DE-OS 43 25 915, in which the fibrous web is permeated with air. The moisture content of the fibrous web is determined by comparing the incoming air and the outgoing air. However, this determination is too imprecise, particularly when used in connection with high web speeds. Moreover, this determination cannot be made in areas without free draw.
SUMMARY OF THE INVENTION
Therefore, the present invention provides a measuring system that allows moisture content of the fibrous web to be measured even without free draw.
In this regard, the measurement can occur in an area in which the fibrous web rests on an essentially water-free, traveling surface.
The water-free surface guarantees as little distortion as possible of the measurement result. Here, the measurement can be made based upon certain types of radiation such that a degree of absorption of the radiation by the water in the material web can be measured as an indicator of the moisture content of the fibrous web. The source and detector of the radiation can be arranged either on different sides or on the same side of the fibrous web.
In an exemplary embodiment, an intensity of radiation passing through the fibrous web and at least the water-free surface can be measured. In an alternative embodiment, the intensity of reflected radiation can be measured.
Infrared radiators with one or more wavelengths and/or ionizing radiation may be particularly suitable for such measuring.
The essentially water-free surface can be formed by a rotating roll, e.g., a smooth one. Moreover, the rotating roll can be formed by, e.g., a drying cylinder, a press roll, a measuring roll, or a guide roll.
The source and/or detector of radiation can be arranged, e.g., in the interior of the roll and can be positionally fixed, at least in the circumferential direction. When using infrared radiators, it may be particularly advantageous for accuracy of measurement if the roll jacket is formed in an optically transparent manner, at least at one point of the circumferential surface, that is guided past the source and detector.
The construction of the apparatus can be simplified if the roll, e.g., formed as a guide roll, includes an optically transparent roll jacket made of, e.g., plastic.
However, it is also possible to house the source of radiation and/or detector of radiation within the roll jacket. In this case, the source and/or detector of radiation should have an optically transparent covering that does not extend beyond the jacket surface of the roll.
Instead of a roll, a traveling belt, e.g., a smooth belt, in the form of a transfer belt or a press belt can be used to form the water-free surface. The surface of the belt or the roll can also be formed, e.g., with a grooved or blind-bored profile. Suction rolls with perforated roll jackets can also be utilized. Further, the possibility exists to form the essentially water-free surface as a relatively intensively dried wire or felt belt. Advantageously, the measurement of the moisture content of the fibrous web can occur at an end and/or after the press section and/or in the drying section. Moreover, the measurement can occur at a position between first and second drying groups, and/or in a region of a calender.
To measure the moisture cross-direction profile of the fibrous web, the source and/or the detector of the radiation can be arranged to traverse the web in a cross-wise direction. It is also possible to provide several sources and/or detectors perpendicular to a fibrous web run direction.
Therefore, the present invention is directed to an apparatus in a machine for at least one of producing and processing the fibrous web. The apparatus includes an essentially water-free traveling surface adapted to guide the fibrous web, and a measuring device positioned and adapted to detect moisture content of the fibrous web while the fibrous web is supported by the essentially water-free traveling surface.
According to another feature of the invention, the measurement device can operate with infrared radiation having at least one wavelength. The detection of moisture content can be based upon a measurement of a degree of absorption of the radiation by water in the fibrous web. The measuring device can include at least one source and at least one detector adapted to respectively transmit and receive the radiation, and the at least one source and at least one detector can be arranged on different sides of the fibrous web. Alternatively, the at least one source and at least one detector can be arranged on a same side of the fibrous web. Further, the at least one source and the at least one detector may include at least one of a silicon semiconductor or lead sulfide.
In accordance with still another feature of the present invention, the measurement device can operate with ionizing radiation. Further, the ionizing radiation may include one of beta- and delta-radiation.
In accordance with a further feature of the instant invention, the essentially water-free traveling surface is formed as a rotating roll. Further, the rotating roll can be a smooth roll, and the rotating roll may be one of a drying cylinder, a press roll, and a guide roll. Further, the measuring device may include at least one source and at least one detector adapted to respectively transmit and receive the radiation, and the at least one source and the at least one detector can be located in an interior of the roll and positionally fixed in a circumferential direction. Further still, the roll can include a roll jacket having at least optically transparent points on a circumferential surface of the roll jacket. The at least optically transparent points may be positioned to at least axially correspond to the fixed position of the at least one source and at least one detector. Moreover, the roll jacket can be composed entirely of an optically transparent material.
According to another feature of the instant invention, the roll can include a roll jacket, and the at least one source and the at least one detector may be located in the roll jacket. Further, the at least one source and the at least one detector can include an optically transparent covering which does not extend beyond an outer surface of the roll jacket.
According to a still further feature of the present invention, the essentially water-free traveling surface may include a traveling belt. The traveling belt may be a smooth belt, and can be one of a transfer belt and a press belt.
In accordance with still another feature of the invention, the essentially waterfree traveling surface can include a dried one of a traveling wire and felt belt.
According to another feature of the present invention, the measurement device can be located in at least one of at the end of a press section, after the press section, in a drying section, and in a region of a calender. Further, the measurement device can be located between a first and a second drying group.
According to a further feature of the instant invention, the measuring device can include at least on
Augscheller Thomas
Steiner Karl
Wegehaupt Frank
Greenblum & Bernstein P.L.C.
Nguyen Dean T.
Voith Sulzer Papiertechnik Patent GmbH
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