Patent Application
20060005936
1. Field of the Invention
The present invention relates to the papermaking arts. More specifically, the present invention relates to fabrics utilized on a papermaking machine. The invention is especially applicable to the production of dryer fabrics, but also may be used for forming fabrics, press fabrics and other industrial fabrics/belts that utilize a pintle or the like.
2. Description of the Related Art
During the papermaking process, a cellulosic fibrous web is formed by depositing a fibrous slurry, that is, an aqueous dispersion of cellulose fibers, onto a moving forming fabric in a forming section of a paper machine. A large amount of water is drained from the slurry through the forming fabric, leaving the cellulosic fibrous web on the surface of the forming fabric.
The newly formed cellulosic fibrous web proceeds from the forming section to a press section, which includes a series of press nips. The cellulosic fibrous web passes through the press nips supported by a press fabric, or, as is often the case, between two such press fabrics. In the press nips, the cellulosic fibrous web is subjected to compressive forces which squeeze water therefrom, and which adhere the cellulosic fibers in the web to one another to turn the cellulosic fibrous web into a paper sheet. The water is accepted by the press fabric or fabrics and, ideally, does not return to the paper sheet.
The paper sheet finally proceeds to a dryer section, which includes at least one series of rotatable dryer drums or cylinders, which are internally heated by steam. The newly formed paper sheet is directed in a serpentine path sequentially around each in the series of drums by a dryer fabric, which holds the paper sheet closely against the surfaces of the drums. The heated drums reduce the water content of the paper sheet to a desirable level through evaporation.
It should be appreciated that the forming, press and dryer fabrics all take the form of endless loops on the paper machine and function in the manner of conveyors. It should further be appreciated that paper manufacture is a continuous process which proceeds at considerable speeds. That is to say, the fibrous slurry is continuously deposited onto the forming fabric in the forming section, while a newly manufactured paper sheet is continuously wound onto rolls after it exits from the dryer section.
The above-mentioned fabrics may take many different forms. For example, they may be woven endless, or flat woven and subsequently rendered into endless form with a seam. Woven fabrics are typically in the form of endless loops, or are seamable into such forms, having a specific length, measured longitudinally therearound, and a specific width, measured transversely thereacross. Because paper machine configurations vary widely, paper machine clothing manufacturers are required to produce fabrics, and other paper machine clothing, to the dimensions required to fit particular positions in the paper machines of their customers. Needless to say, this requirement makes it difficult to streamline the manufacturing process, as each fabric must typically be made to order.
Fabrics in modern papermaking machines may have a width of from 5 to over 33 feet, a length of from 40 to over 400 feet and weigh from approximately 100 to over 3,000 pounds. These fabrics wear out and require replacement. Replacement of fabrics often involves taking the machine out of service, removing the worn fabric, setting up to install a fabric and installing the new fabric. Because of the solid support beams for dryer sections, all dryer fabric must have a seam. Installation of the fabric includes pulling the fabric body onto a machine and joining the fabric ends to form an endless belt.
The seam region of any workable fabric must behave in use as close to the body of the fabric in order to prevent the periodic marking by the seam region of the paper product being manufactured.
Fabrics can be formed completely of spirals as taught by Gauthier, U.S. Pat. No. 4,567,077; which is incorporated herein by reference. In this case, the spirals are connected to each other by at least one connecting pin. In theory, the seam can therefore be at any location in the fabric body where a connecting pin may be removed. An advantage of a spiral fabric versus a woven fabric is the seam is geometrically similar to the fabric body.
The present invention provides a pintle or connecting element for use in holding together the spirals of a spiral link fabric. The connecting element deforms under compression or tension during processing, thereby reducing fabric thickness and permeability.
The invention provides a connecting element for use in an industrial fabric. The connecting element includes a center portion and a plurality of lobes extending therefrom. The industrial fabric is preferably a spiral link fabric. The connecting element deforms under compression or tension, resulting in a thinner fabric and reducing the permeability of the fabric to air, water, and the like.
The present invention will now be described in more complete detail with reference being made to the figures wherein like reference numerals denote like elements and parts, which are identified below.
For a more complete understanding of the invention, reference is made to the following description and accompanying drawings, in which:
a is an enlarged view of the connecting element of
b is an enlarged view of the connecting element of
A preferred embodiment of the present invention will be described in the context of a papermaking dryer fabric. However, it should be noted that the present invention may be applied to spiral link fabrics used in other sections of a paper machine, as well as to those used in other industrial settings. The spiral link fabric includes a plurality of transverse spirals which may be interdigitated and connected together by a connecting element. Note the present invention may have applications in other type fabrics or in seaming applications where pintles of this type may be desirable.
An embodiment of the present invention will now be described with reference to
The connecting element 2 may include a center portion 6 having a substantially circular cross-section and a number of lobes 10 each having an outer surface 4 and each extending from the central portion. In one embodiment, the connecting element 2 has five lobes 10 and accordingly may be termed a pentalobal yarn. Adjacent lobes are separated from each other by a groove 8 having a predetermined shape such as a “C” shape. The outer surface 4 of the connecting element 2 may have a curved shape, such as illustrated in
Connecting element 2 may be a homogenous monofilament formed from any polymeric resin, such as polyamide and polyester resins. Connecting element 2 can, as will be appreciated by those skilled in the art, contain a wide variety of additives typically used in the preparation of monofilaments to modify the appearance and performance characteristics, such as anti-oxidants, dyes, pigments, antistatic agents and ultraviolet stabilizers. Alternatively, the connecting element 2 may be fabricated from a metal or metals or other materials, which may or may not contain additives. Such connecting element 2 may be formed from an extrusion process (such as a melt extrusion process) using a die. In such situation, the shape of the die may determine the shape of the connecting element.
As mentioned above, the original shape of the connecting element 2 may allow it to deform under compression or tension to obtain a fabric thickness smaller than the original thickness of the fabric spiral coils. For example, in a calendering process, the spiral link fabric may be pressed between two rollers forming a nip. Such compression will cause the connecting element to deform and reduce the overall thickness dimension of the spiral coil.
Further, stuffer yarns 24 may be inserted or otherwise disposed between or within spirals 14 or 16 so as to fill gaps therein to further reduce the permeability of the fabric 12. Stuffer yarns 24 may be yarns or strips of material and may have any shape suitable for the purpose.
a is a cross-sectional view of connecting element 2 disposed in a loop of a spiral link fabric 112 before being subjected to an operational compression or tension load. In such arrangement, spiral coils 34 and 36 have been interdigitated to form a channel 38 having a substantially circular or oval-shape with a height H1. When the fabric 112 is compressed during processing, for example in a calendering operation, coils 34 and 36 and connecting elements 2 may be deformed or changed so as to have a height H2, as shown in
Therefore, the present connecting element 2 will result in a thinner fabric with lower permeability.
Although the connecting element has been described as having five lobes (pentalobal) and a substantially circular cross-sectional shape, the present invention is not so limited. Instead, the connecting element may have any cross-sectional shape that deforms under processing compression or tension to yield a fabric with a thickness smaller than the thickness of the original fabric. In addition, the present connecting element may have any number of lobes 10 each having any shape. As an example, grooves 8 may have a “C”-shape or a “U”-shape cross-section, or a combination thereof. As another example, each of the lobes and grooves may have different sizes and/or shapes.
Modifications to the above would be obvious to those of ordinary skill in the art, but would not bring the invention so modified beyond the scope of the present invention.
Thus by the present invention its advantages are realized and although preferred embodiments have been disclosed and described in detail herein, their scope should not be limited thereby; rather their scope should be determined by that of the appended claims.
This application is based upon and claims the benefit of U.S. Provisional Patent Application Ser. No. 60/529,488 filed Dec. 15, 2003 entitled “PENTALOBEL YARN AS PINTLE FOR SPIRAL FABRICS”, the disclosure of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60529488 | Dec 2003 | US |
