1. Field of the Invention
The present invention relates to a method for producing a felt belt, particularly a press felt, for a paper, cardboard, or tissue machine.
2. Description of the Related Art
Felt belts, in particular press felts for paper, cardboard, or tissue machines, generally have a base structure providing dimensional stability to the felt, which is needled on both sides with one or more non-woven fibrous layers.
Press felts may be provided either as continuous belts or as continuous belts with a seam. Press felts embodied as continuous belts have the disadvantage as compared to press felts with a seam that such press felts are difficult to install in the paper machine since they cannot be pulled into the machine as an open belt.
As a rule, the base structure of the known press felts is woven. Woven structures have the disadvantage that they are often very complex to produce. Therefore, the prior art already proposes press felts with non-woven base structures in which the base structure has, for example, a longitudinal thread structure. Such a basic structure formed by a longitudinal thread structure is known, for example, from U.S. Pat. No. 4,495,680. Most of the press felts having longitudinal thread structures known up to now are embodied as continuous belts.
In addition, a method is known from EP1808527A1 by means of which a seamable press felt may be produced. In practice, however, this method has the disadvantage in many cases that, in an intermediate stage of production, the structure lacks the necessary stability in the longitudinal thread direction, therefore, complicating handling during the production process.
What is needed in the art is a method for the production of a seamable base structure having a longitudinal thread structure that does not have the disadvantages discussed above.
The method of the present invention includes the steps of first creating a helically wound longitudinal thread structure, applying a transverse reinforcement structure to the longitudinal thread structure and connecting it to the longitudinal thread structure only in a later step. In this manner, a tube-like composite structure is obtained. Subsequently, opposing sections of the tube-like composite structure are placed one atop the other such that the tube-like composite structure forms a flat structure whose length corresponds to approximately half the circumference of the tube-like structure and that provides seam loops on its opposite longitudinal ends formed by the at least one helically wound longitudinal thread. Then, the flat structure is made continuous in that the opposing seam loops are merged and connected to one another. The sections of the flat structure placed one atop the other are furthermore connected to one another in order to form a base structure.
According to a second embodiment of the present invention, multiple flat structures are produced that are placed in a row next to one another and connected to one another at the seam loops in order to form a continuous belt. This means that the flat structures placed one behind the other form a continuous belt together.
In both embodiments of the present invention a longitudinal thread structure forming a “closed tube” is first produced, which has the necessary tensile strength for the subsequent handling. By means of the alternative embodiment, it is possible to build base structures for press felts of virtually any length using identically constructed modules.
The thread(s) is/are helically wound, for example, around two rollers located at a distance from one another and oriented essentially parallel to one another, with the progression of the helical winding, i.e., the winding direction, occurring perpendicularly to the two rollers. Here, the length of a winding corresponds to the circumference of the tube-like composite structure. The transverse reinforcement structure may be connected, directly or indirectly, for example, via an intermediate layer, to the longitudinal thread structure.
It is possible for only one single longitudinal thread to be helically wound in order to produce the longitudinal thread structure. However, it is also possible for a skein of longitudinal threads to be helically wound in order to form the longitudinal thread structure. The one or more longitudinal thread(s) forming the longitudinal thread structure is/are embodied as monofilament thread(s). By providing a longitudinal thread structure made of one or more longitudinal thread(s) whose seam loops are formed by monofilaments, the present invention provides a press felt that is particularly easy to seam.
A third embodiment of the method according to the present invention provides for the belt to be made continuous or for the formation of a continuous belt before the connection of the sections placed one atop the other. By virtue of the fact that the base structure is first made continuous before the layers and/or sections of the tube-like composite structure placed one atop the other are connected to one another and their position relative to one another is thus fixed, it is possible to correct, for example, discrepancies in length and warping in the flat structure. For this purpose, the flat structure(s) may be tensed in its/their longitudinal direction after being made continuous. This may occur, for example, in that the flat structure that has been made continuous or the continuous belt is guided over a pair of rollers disposed at a distance from and parallel to one another and the distance between the rollers is increased in the longitudinal direction of the flat structure.
A fourth embodiment of the present invention proposes that the structure be made continuous or that a continuous belt be formed after the sections placed one atop the other have been connected.
A further development of the present invention provides for at least one carrier layer to be applied to the longitudinal thread structure after the production of the longitudinal thread structure and before the application of the transverse reinforcement structure. Alternately, it is also conceivable for the carrier layer to be applied to the longitudinal thread structure together with the transverse reinforcement structure. In such a case, the transverse reinforcement structure is, for example, first connected to the carrier layer before this arrangement is applied to the longitudinal thread structure and connected thereto. This may occur, for example, in order to fix the distance between sequential thread windings before applying the transverse reinforcement structure. In such a case, the transverse reinforcement structure, for example, has no direct contact with the longitudinal thread structure; rather, the transverse reinforcement structure is connected to the longitudinal thread structure via the carrier layer.
A fifth embodiment of the present invention provides for the longitudinal thread structure and the transverse reinforcement structure to be connected to one another via the carrier layer. This means that the carrier layer can be disposed between the transverse reinforcement structure and the longitudinal thread structure. Moreover, the carrier layer may, for example, be formed alone or in combination by a non-woven fibrous layer or a film layer.
The carrier layer, which is embodied as a non-woven fibrous layer, may comprise hot melt adhesive fibers. In this case, it is conceivable for the longitudinal thread structure be connected to the non-woven fibrous layer by the hot melt adhesive fibers being melted and resolidified and/or by the transverse reinforcement structure being connected to the non-woven fibrous layer by the hot melt adhesive fibers being melted and resolidified.
Before melting the hot melt adhesive fibers of the non-woven fibrous layer, or as an alternative thereto, it is moreover conceivable for the non-woven fibrous layer to be needled to the longitudinal thread structure and/or to the transverse reinforcement structure. In such a case, the longitudinal thread structure and/or the transverse reinforcement structure can be at least partially embedded in the non-woven fibrous layer. This means that the connection between the thread structure and the carrier layer and/or between the transverse reinforcement layer and the carrier may occur by means of needling or melting. Alternatively or in addition, adhesion is also conceivable.
If the longitudinal thread structure and the transverse reinforcement structure are connected to the non-woven fibrous layer comprising hot melt adhesive fibers by the hot melt adhesive fibers being melted and resolidified, the longitudinal thread structure, the transverse reinforcement structure, and the non-woven fibrous layer can be hot calendered together, for example, in that they are guided together around a heated roller.
The transverse reinforcement structure may comprise a transverse thread arrangement, which may be, for example, alone or in combination, a woven fabric, a knitted fabric, a knotted fabric, a gauze fabric, or a transverse thread structure.
If the transverse thread structure is, for example, a woven or knitted fabric, it may include transverse threads and longitudinal threads that are relatively thin in comparison to the transverse threads, and which hold the transverse threads in position. However, the transverse threads may also be held in position by a film or fibrous non-woven layer upon which the transverse threads are fixed.
In order to produce the base structure in a cost-effective manner, it is conceivable, for example, for the transverse reinforcement structure to be formed by multiple transverse reinforcement modules extending only over part of the length of the longitudinal thread structure, which are disposed one behind the other on the longitudinal thread structure in the longitudinal direction of the felt belt in order to form the transverse reinforcement structure. The transverse reinforcement modules may extend over the width of the longitudinal thread structure. In addition, the transverse reinforcement modules may be formed with a transverse reinforcement output strip such that the transverse reinforcement modules may be placed on the longitudinal thread structure as follows:
a) laterally placing the transverse reinforcement module output strip relative to the longitudinal thread structure, i.e., transverse to the longitudinal direction of the longitudinal thread structure;
b) flatly depositing the transverse reinforcement module output strip onto the longitudinal thread structure;
c) separating the section of the transverse reinforcement module output strip deposited on the longitudinal thread structure from the remaining transverse reinforcement module output strip in order to form a transverse reinforcement module;
d) moving the longitudinal thread structure in its longitudinal direction relative to the transverse reinforcement module output strip on a path that essentially corresponds to the width of the transverse reinforcement module output strip; and
e) repeating steps a) to d) such that the transverse reinforcement modules are disposed lying one behind the other in the longitudinal direction of the felt belt.
The method of the present invention may be carried out such that, when the base structure has been completely produced, each transverse reinforcement module placed on the longitudinal thread structure extends over the width of the longitudinal thread structure and the transverse reinforcement modules disposed lying one behind the other combine to measure the length of the longitudinal thread structure.
The production of the base structure is particularly cost effective when the transverse reinforcement module output strip is present as rolling stock and is unrolled from the roll when it is laterally placed.
In order to produce the carrier layer in a cost-effective manner, a winding method is used such that a carrier layer extending over the entire width of the felt belt may be produced by the helical winding of a partial-width carrier strip. As a result, one embodiment of the invention provides for the carrier layer to be produced in that a carrier strip extending only over part of the provided width of the felt belt is helically wound in a continuous fashion in the direction of the provided width of the felt belt, particularly up to the provided width of the felt belt. If the carrier strip is helically wound, depending on the present requirements, for example, whether the carrier layer is to be embodied in single or multiple layers, edges facing one another may be placed flush or in a regionally overlapping manner.
After the production of the base structure, it may be placed under tension and subjected to a heat treatment in order to attain a high level of dimensional stability. The seam loops that have been merged, or are to be connected to one another, are connected by a fixing wire.
Furthermore, in order to form the felt belt, the base structure may be needled on its top side to at least one non-woven fibrous layer and/or on its bottom side to at least one non-woven fibrous layer. Here, for example, the outermost of the non-woven fibrous layers on the top side of the base structure provides the paper side of the felt belt. Moreover, the outermost of the non-woven fibrous layers on the bottom side of the base structure provides the machine side of the felt belt.
In order to achieve a good connection of the one or more non-woven fibrous layer(s) to the base structure, another embodiment of the present invention provides for the transverse reinforcement structure to include multifilament threads. Here, the multifilament threads may particularly be twisted. The transverse threads of the transverse reinforcement structure are embodied as multifilament threads. The embodiment described above may also provide for the longitudinal thread(s) of the longitudinal thread structure being embodied as monofilament thread(s).
In order to influence the volume structure and/or the surface structure of the non-woven fibrous layers, particulate polymer material may be incorporated into at least one non-woven fibrous layer that is needled onto the top side and/or the bottom side of the base structure, said polymer material attaching to fibers of the non-woven fibrous layer and forming a porous composite structure therewith.
In this context, it is conceivable, for example, for the particulate polymer material to be melted after its incorporation into the non-woven fibrous layer and, after it resolidifies, to form the porous composite structure along with the fibers of the non-woven fibrous layer.
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
a-1e illustrate a first embodiment of a method according to the present invention;
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
Referring now to the drawings, and more particularly to
a illustrates the production of longitudinal thread structure 1 of the base structure. To this end, skein of threads 2 parallel to one another are helically wound around two rollers 3, 4 disposed at a distance from and essentially parallel to one another, with the progression of the helical winding, i.e., the winding direction, occurring perpendicularly to the two rollers in the direction of the provided width (CMD) of the felt belt up to the provided width of the felt belt. Here, the length of one winding corresponds to the circumference of thread structure 1 thus formed.
In the step of the method of the present invention shown in
The status of the method of the present invention shown in
The needling allows longitudinal thread structure 1 and/or transverse thread structure 6 to at least partially, for example, completely, be embedded in non-woven fibrous layer 5.
In the step of the method of the present invention shown in
e illustrates the steps of flat structure 13 being made continuous by combining opposing seam loops 16, 17 and connecting the same to one another by means of fixing wire 18 and connecting sections 11, 12 of flat structure 13 placed one atop the other to form base structure 19. In the present case, the connection of sections 11, 12 of flat structure 13 placed one atop the other occurs by needling, for example, by means of needle arrangement 20.
In the present case, the structure is made continuous before the connection of sections placed one atop the other. To this end, after being made continuous, flat structure 13 is tensed in its longitudinal direction MD. In the present case, this occurs in that the flat structure, which has been made continuous, is guided over a pair of rollers 21, 22 disposed at a distance from and parallel to one another and the distance between rollers 21, 22 is increased in the longitudinal direction MD.
To this end, longitudinal thread structure 23 is provided having a length and a width. Non-woven fibrous layer 24 is deposited on longitudinal thread structure 23 that extends over the length and width of the longitudinal thread structure and that is needled with longitudinal thread structure 23 to form longitudinal reinforcement module 33 such that the longitudinal thread structure is disposed inside non-woven fibrous layer 24. Moreover, transverse reinforcement module output strip 25 is provided, having a length and a width, which is wound onto roll 26 and is present as rolling stock. Transverse reinforcement module output strip 25 is laterally placed relative to longitudinal reinforcement module 33 in that respective free end 27 of transverse reinforcement module output strip 25 is guided from one longitudinal edge 28 of longitudinal reinforcement module 33 to the other longitudinal edge 29 of longitudinal reinforcement module 33 (see arrow). After or during its placement, transverse reinforcement module output strip 25 is deposited on longitudinal reinforcement module 33. After being deposited, the section of transverse reinforcement module output strip 25 placed on longitudinal reinforcement module 33 is separated from remaining transverse reinforcement module output strip 25, forming transverse reinforcement module 30a, 30b.
As an alternative, the section of transverse reinforcement module output strip 25 to be placed on longitudinal reinforcement module 33 may already be separated from remaining transverse reinforcement module output strip 25 during the deposition of transverse reinforcement module output strip 25 onto longitudinal reinforcement module 33 in order to form transverse reinforcement module 30a, 30b. As may be seen from the depiction in
In the depiction according to
After the deposition of transverse reinforcement module 30a onto longitudinal reinforcement module 33, longitudinal reinforcement module 33 is moved in its longitudinal direction MD on a path relative to transverse reinforcement module output strip 25 that essentially corresponds to the width of transverse reinforcement module output strip 25. By repeating the steps described above, transverse reinforcement modules 30a, 30b, . . . are disposed lying one after the other in the longitudinal direction of the felt belt.
In the present case, the method of the present invention is carried out such that, when base structure 31 is completed, each transverse reinforcement module 30a, 30b deposited on longitudinal reinforcement module 33 extends over the width of longitudinal reinforcement module 33 and transverse reinforcement modules 30a, 30b disposed lying one after the other are expanded by additional transverse reinforcement modules, which are not shown here, to form an uninterrupted layer.
The deposited and cut transverse reinforcement modules 30a, 30b, . . . are connected to non-woven fibrous layer 24 and longitudinal thread structure 23 in that longitudinal thread structure 23, non-woven fibrous layer 24, and transverse reinforcement module(s) 30a, 30b, . . . disposed thereon are subjected together to the effects of heat under pressure, in that they are guided around heated roller 32. In this manner, transverse reinforcement modules 30a, 30b, non-woven fibrous layer 24, and longitudinal thread structure 23 are pressed with one another, which ensures a good bond.
While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
Number | Date | Country | Kind |
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DE 102008002033.8 | May 2008 | DE | national |
DE 10200900251.5 | Apr 2009 | DE | national |