Patent Application
20090211722
1. Field of the Invention
The invention is directed to forming a seamable belt for a paper making machine and, in particular, a seamable belt base for a paper making machine.
2. Discussion of Background Information
It is known from International Publication No. WO 89/12717 that a seam capable base for a press fabric can be created by “folding” a tube of woven fabric and removing cross-direction (CD) yams at the folds on each end. In this way, machine direction (MD) yarns at these ends or folds can then function as the seam loops. The ends or seam loops of the base can be aligned and connected with a pintle to form an endless base for the belt. The base can be needled and finished in any conventional matter in order to form a normal press seam fabric.
In other methods, it is known that the above-noted tube of fabric can be constructed with a spiraled “multiaxial” method. However, to use endless woven or spiraled tubes in the above-noted manner, the tubes have to be produced to length based on the order. Further, as these tubes are generally only about 1-1.5 m wide, a number of these folded tubes must be combined with MD joins in order to achieve a width of 10-12 m, which is generally utilized in paper making machines. The ends of these tubes can be joined together by forming MD yarn loops by removing CD yams.
Further, as an array of parallel yams “reinforced” with needled batt, resins, or other nonwovens can be utilized in forming the described tube for the base, a strong single layer top ply fabric can be provided over the joined area, or needled batt, added resin, thermoplastic “welding”, etc. to keep the join in the two fabric ends intact for processing. Still further, a knit fabric can be used where the loops are provided as a spiral link.
In a further alternative, it is known to position a membrane “insert” within the tube, e.g., prior to folding.
The present invention is directed to a method of forming a belt for a paper making machine. The belt includes a base structure composed of a woven material or fabric in which the MD ends of the base structure are formed by folding over portions of the MD ends of the fabric. The folded over portions of the MD ends of the fabric can be attached to the bottom side of the base. Seam loops can be formed in the MD ends of the base structure, e.g., by forming a separation between the CD threads, and preferably without removing CD threads. The woven fabric can be an endless woven or flat woven fabric, and can be of single layer construction.
In an exemplary embodiment of the invention, the portions of the MD ends of the fabric can be folded over so the MD ends of the fabric can be arranged to in close proximity to, and preferably abutting, each other, or can be arranged to overlap or be intermeshed with each other. The MD ends of the fabric can be arranged to either abut or overlap each other in close proximity to, e.g., within 4′, preferably between 1″-36″, and more preferably between 12″ and 36″ of one of the fold ends of the base structure. Further, the folded portions of the MD fabric can be attached to the bottom side of the base structure by, e.g., sewing an MD seam in a region of the MD end of the fabric and/or sewing an MD seam joining both MD ends to the bottom side of the base structure.
According to another aspect of the invention, the base structure can include an enveloped insert composed of, e.g., a formed polyurethane composite nonwoven membrane, such as a SPECTRA membrane manufactured by Voith Fabrics, or another non-flat woven fabric, preferably including an elastomer, or knit material. The insert may be smaller than a full width of the base structure as long as the insert provides desired stiffening and/or fiber bonding, e.g., in the form of a low melt fabric or scrim.
The present invention is directed to a belt for a paper making machine that includes a flat woven material having a top side surface and a bottom side surface and two terminal ends separated in a machine direction. Folds formed in the flat woven material are separated in the machine direction, so that the two terminal ends are located under the bottom side surface. Seam loops are located at the folds. The two terminal ends one of are arranged adjacent each other and overlap each other in a region offset from a center between the folds.
According to a feature of the invention, portions of the flat woven material from the two terminal ends to the folds can be adhered to the bottom side surface.
According to another feature of the invention, the two terminal ends may be sewn to the bottom side surface.
Further, the two terminal ends offset from the center can be located within 4″ of one of the folds. Moreover, the two terminal ends offset from the center may be located between 1″ to 36″ from the one of the folds.
In accordance with still another feature of the present invention, a density of cross-direction fibers in a region of the seam loops is greater than a density of cross-direction fibers toward a center between the folds.
According to a further feature, an insert can be located between the folds, the bottom side surface and the two terminal ends arranged adjacent each other. Further, the insert can include polyurethane, and can be a nonwoven membrane. The insert can also include another flat woven fabric, and the insert, the two terminal ends, and the bottom side surface may be sewn together.
In accordance with still another feature of the instant invention, a pintle can be insertable through the seam loops, thereby forming a belt seam.
According to another feature, a batt layer can be needled onto at least one of the top side surface and a surface comprising the terminal ends.
The invention is directed to a method for forming a belt for a paper making machine from a flat woven fabric having a top side surface and a bottom side surface and two terminal ends separated in a machine direction. The method includes forming folds in the flat woven fabric so the two terminal ends are positioned under the bottom side surface and one of adjacent each other and overlapping each other, attaching the two terminal ends and the bottom side surface together in a region offset from a center between the folds, and separating adjacent cross direction threads in the folds to form seam loops,
In accordance with a feature of the instant invention, the attaching may include sewing the terminal ends and the bottom side surface together.
According to another feature of the invention, the separating of the adjacent cross direction threads in the folds can create a greater density of cross-direction fibers in a region of the seam loops than in a region of the center between the folds.
In accordance with still another feature of the present invention, the two terminal ends and the bottom side surface can be attached within 4′ of one of the folds. Further, the two terminal ends and the bottom side surface are attached at a located between 1″ to 36″ from the one of the folds.
Moreover, the method can further include inserting an insert between the folds, the bottom side surface and the two terminal ends arranged adjacent each other. The insert may include a polyurethane nonwoven membrane.
The method may also include sewing together the insert, the two terminal ends, and the bottom side surface.
According to still another feature of the invention, the method can also include inserting a pintle through the seam loops, thereby forming a belt seam.
In accordance with still another feature of the invention, the method can include needling a batt layer onto at least one of the top side surface and a surface comprising the terminal ends.
According to another feature, the method can include further include fringing the two terminal ends. The fringed terminal ends can be arranged to overlap, and the overlapped fringed terminal ends to the bottom side surface may be attached by at least one stitch.
In accordance with still yet another feature of the present invention, the method can include coupling a two layer fabric belt to one of the top side surface and a surface including the terminal ends.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.
The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:
The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the,art how the several forms of the present invention may be embodied in practice.
According to embodiments,
By way of non-limiting example, woven fabric 1 can be produced on wide weaving loom, e.g., a twelve (12) meter wide weaving loom for robotic flat stock fabric weaving. While twelve meters is wide enough for existing paper machines, it may be advantageous to select smaller loom sizes to minimize or avoid waste for belts having a smaller CD dimension. Moreover, the fabric can be formed with, e.g., eighteen (18) ends per inch of 0.50 mm nylon 6 MD yams and eighteen (18) ends per inch of the same yarns in the CD direction using a single layer plain weave. The fabric may be cut to length from a stock piece when orders are received. Further, it may be beneficial to perform the cutting with a hot knife so as to fuse the cut ends.
Further, woven fabric 1 can be selected with MD and CD interwoven textile yam systems because these fabrics are more stable in the CD and/or MD directions, thereby allowing predictability in running size, and in stretching, widening or shrinking while running. Further, it may also be advantageous to utilize a full width stock fabric so that no MD joins are needed. In this way, the belt can then be easily assembled into a finished fabric in any conventional manner, which can include, e.g., washing the felt, applying a thermal treatment bonding to the felt, etc.
An end portion of woven fabric 1, i.e., from a fold line 6 to terminal end 2, can be folded over onto itself, and another end portion of woven fabric 1, i.e., from fold line 7 to terminal end 3, can be folded over onto itself, as shown in
Moreover, the invention can create substantially increased CD yarn density adjacent to the seam loops by “slipping” the yarns back into the body weave, with proper use to mechanical force, temperature, added stitching yarns, etc. In this way, fiber bonding at the seam can be improved, and loops sizes can be more consistent. Moreover, the time consuming and damage prone operation of removing CD yams can be minimized or preferably eliminated, depending on the type of construction used.
Further still, once the MD thread loops are formed, a stitch can be sewn in the CD direction along or near the base of loops 6′ and 7′. Further, the stitch can be formed between the MD yarns to prevent CD migration and keeps the MD threads aligned.
As shown in
Adjacent, and preferably abutted, terminal ends 2 and 3 are arranged, not in the center of the base structure between folds 6 and 7 of woven fabric 1, but instead are offset from the center and located, e.g., in close proximity, e.g., within 4′, preferably between 1″-36″, and more preferably 12″-36″, to one of seam loop end 6′ or 7′. By positioning the abutted ends in close proximity to one of the seam loop ends 6′ or 7′, each end and/or the join can be sewn in the cross-direction using, e.g., industrial sewing machines of “conventional” throat depth.
In an advantageous alternative embodiment, terminal ends 2 and 3 can be fringed by removing CD threads, e.g., about 0.25″ of CD threads from the terminal ends 2 and 3. As shown in
After the base structure of
Moreover, the belt or base structure of the invention can be seamed and placed on a needling device, which is generally known in the art. A batt layer 10 can be needled onto the seamed base structure to cover seam 9 so as to prevent disadvantageous marking of the web due to a variance in the caliper at seam 9. Fibers in batt layer 10 can be needled or punched through at least one and preferably the two plies of the folded woven fabric 1 forming the belt or base structure, thereby providing further stability. Of course, it is likewise understood that batt layer 10 can be needled onto the belt or base structure prior to forming seam 9. In such an event, it may be advantageous to provide a suitable and additional amount of batt fiber 10 arranged to extending or hang over at least one of the seam loop ends so that this additional amount of batt fiber will cover over seam 9 after the seaming of the belt.
In an alternative embodiment illustrated in
Insert 21 is generally not relied upon for dimensional stability, since such stability can be obtained from the base structure, but rather to improve fabric performance in the press nip for water handling, preferably with an elastomeric content fabric maintaining a separation between the two woven plies, and to provide reinforcement for the CD join formed by terminal fabric ends 22 and 23. To reinforce the CD join of terminal ends 22 and 23, or for other performance reasons, insert 21 need not extend to the full or entire width of woven fabric 20. Instead, it can be just near the seam edge or seam ends to provide stiffening and fiber bonding, in the form of a low melt fabric or scrim, etc.
In another alternative embodiment, a non-woven parallel array of MD yarns can be laminated onto the bottom side of the flat woven seam base, e.g., using meltable yarns that fuse into the needled batt. This embodiment may be advantageous in that these added yarns may protect the joined ends of the flat base from abrasive wear and reduce the risk of the join failing on the paper machine. Moreover, while other fabric laminates may also be used without departing from the spirit and scope of the invention, wound yarns may provide beneficial results. Further, these yarns can be combined with the above-discussed insert to achieve an extremely compaction resistant multi-layered structure that is easy to pin with a single seam, and very efficient to produce.
In a further embodiment of the invention, the folded fabric belt or belt base formed in accordance with the features of the present invention can be coupled to, e.g., laminated with, another belt, such as a single ply fabric belt or belt base, a double ply fabric belt or belt base, or a folded fabric belt or belt base formed, e.g., in accordance with the invention. In this manner, a 1+2 or a 2+2 double seam fabric belt can be advantageously formed. Of course, this description is for the purpose of ease of explanation and understanding of the invention and is not intended to limit the invention to any particular embodiment or arrangement. Thus, it is understood that the belt or belt base of the invention can be joined with or to other belts or belt bases without departing from the spirit and scope of the invention.
The above-discussed embodiments of the invention have been provided to explanation and to facilitate the understanding of the invention. However, it is understood that the invention is neither limited to a single layer structure, nor to homogenous yarn selection in the MD or the CD. A further advantage of flat weaving can be that side by side MD yam systems coming from two warp beams can be utilized, whereby one system is cabled filaments to hold batt and provide density, and one system is solid monofilaments to provide strong seam loops. Still further, to assist in sheet transfer, it is contemplated to use a different density of MD cabled yarns near the edge of the fabric as compared to the center. Also, CD yams can be selected to specific performance enhancements, e.g., having yams for width stability, but also could combine with elastomeric yarns, low melt bonding yarns, etc., without departing from the spirit and scope of the invention.
It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.
