Patent Abstract:
A covering for paper machines, paperboard machines or tissue machines, which is constructed from a construction kit includes a plurality of prefabricated web-shaped material layers. Each web-shaped material layer is configured dependent upon a category and operating conditions of the covering, and the plurality of prefabricated web-shaped material layers are stacked atop one another and are joined to one another at least in sections, two-dimensionally, and in a manner that prevents the plurality of prefabricated web-shaped material layers from being detached. The invention also relates to a method for producing the inventive covering.

Full Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention relates to a method for the modular production of coverings for paper machines, paperboard machines or tissue machines and to a covering for a paper machine, paperboard machine or tissue machine.  
         [0003]     2. Description of the Related Art  
         [0004]     Paper machines, paperboard machines or tissue machines have coverings in the forming section, press section and drying section.  
         [0005]     The different categories of coverings, namely forming meshes, press felts and dryer fabrics, must meet many different requirements, for example with regard to dewatering behavior, moisture adsorption capacity and the like.  
         [0006]     Furthermore, coverings of the same category must meet different requirements depending on the operating conditions. For example, the requirements for the structure of the side of a forming mesh facing the fibrous web in the production process for graphic paper differ fundamentally from those for the production of tissue.  
         [0007]     Due to the different categories of coverings described above, each of which has to meet many different requirements, the historical development has seen the manufacturers of coverings produce, for practically every category and operating condition, a covering type which differs almost fundamentally from the covering types of other categories and operating conditions.  
         [0008]     For example, covering manufacturers often produce forming meshes with different weave patterns for specific customers.  
       SUMMARY OF THE INVENTION  
       [0009]     The current invention provides a method for providing coverings, as well as coverings which are easier and cheaper to produce than those coverings known from the prior art.  
         [0010]     The invention is based on the idea of reducing the production costs of coverings for paper machines, paperboard machines or tissue machines by simplifying the production method for the entire product range of paper machine coverings.  
         [0011]     The method according to the invention provides for producing different categories of coverings modularly from a construction kit of prefabricated web-shaped material layers. According to the invention, several web-shaped material layers are selected from the construction kit of prefabricated web-shaped material layers depending on the category and operating condition of the covering to be produced. The web-shaped material layers selected from the construction kit are stacked atop one another and joined to one another at least in sections, two-dimensionally, and in a manner that prevents them from being detached.  
         [0012]     In other words, a method is proposed which provides a construction kit of prefabricated material layers. By defining a construction kit of prefabricated web-shaped material layers for the entire product range of paper machine coverings and by selecting prefabricated web-shaped material layers from the construction kit, depending on the category and the operating conditions of the covering, the number of different material layers and, for example, weave structures is greatly reduced.  
         [0013]     Whereas in the past a different weave structure was required for each operating condition for example, it is possible in accordance with the invention to produce coverings for the different categories and operating conditions by combining several of the prefabricated web-shaped material layers.  
         [0014]     According to one embodiment, provision is made for the order in which the selected web-shaped material layers are stacked to depend on the category and the operating conditions of the covering. The flexibility in using the prefabricated material layers is thus increased, as different properties of the covering can be achieved depending on the order in which the selected web-shaped material layers are stacked.  
         [0015]     In this connection it should be noted that the prefabricated web-shaped material layers are constructed such that they fulfill, on their own or in combinations, specific functions such as damping properties, dimensional stability, wear stability, surface properties, liquid adsorption capacity and the like.  
         [0016]     According to another embodiment, provision is made for the construction kit of prefabricated material layers to include at least one material layer influencing the surface of a fibrous web and at least one wear-stable material layer. In this case the material layer influencing the surface of the fibrous web is understood to be the material layer which terminates the covering in the direction of the fibrous web. Furthermore, the wear-stable material layer is understood to be the material layer which terminates the covering in the direction of the paper machine.  
         [0017]     According to another embodiment, provision is made for the construction kit of prefabricated material layers to include at least one dimensionally stable material layer. The dimensionally stable material layer can be configured either as a material layer which is constructed separately from the two previously mentioned material layers or as an integral component of the one or other previously mentioned material layers.  
         [0018]     Various possibilities for the construction of the above-mentioned material layers are conceivable.  
         [0019]     Another embodiment of the invention provides for the material layer influencing the surface of the material web to be a textile or a non-textile areal structure.  
         [0020]     Another embodiment of the invention provides furthermore for the wear-stable material layer to be a textile or a non-textile areal structure.  
         [0021]     Another embodiment of the invention provides for the construction kit of prefabricated material layers to include at least one material layer influencing the liquid adsorption capacity. The material layer influencing the liquid adsorption capacity can be constructed either separately from the previously mentioned material layers or as an integral component of one of the previously mentioned material layers.  
         [0022]     The material layer influencing the liquid adsorption capacity can be constructed either as a material layer with a high liquid adsorption capacity or as a material layer with a low liquid adsorption capacity.  
         [0023]     A material layer with a high liquid adsorption capacity should have a liquid adsorption capacity which is greater than 50% of the total capacity of the material layer, in particular preferably greater than 70% of the total capacity of the material layer and most preferably greater than 80% of the total capacity of the material layer.  
         [0024]     A material layer with a low liquid adsorption capacity should have a liquid adsorption capacity which is less than 50% of the total capacity of the material layer, in particular preferably less than 30% of the total capacity of the material layer and most preferably less than 20% of the total capacity of the material layer.  
         [0025]     According to another embodiment of the invention, provision is made for the construction kit of prefabricated web-shaped material layers to include at least one anti-rewetting material layer.  
         [0026]     Furthermore, other embodiments provide for the dimensionally stable material layer and/or the material layer influencing the liquid adsorption capacity and/or the anti-rewetting material layer to be textile or non-textile areal structures.  
         [0027]     A textile areal structure is understood to be a weave structure or a fleece or a thread plaiting or a warp knitting.  
         [0028]     Furthermore, a non-textile areal structure is understood to be a structured and/or penetrated film or a structured and/or penetrated membrane and/or a foamed layer.  
         [0029]     It is advantageous, for example, for the material layer with a large liquid adsorption capacity to be a foamed layer.  
         [0030]     Furthermore, it is advantageous for the material layer with a small liquid adsorption capacity to be a foamed layer or a penetrated film or a membrane.  
         [0031]     Furthermore, it is advantageous for the foamed layer to have a defined pore size. By providing a defined pore size it is possible, for example, to establish the liquid adsorption capacity and hence the dewatering behavior. Furthermore, it is also conceivable for the foamed layer belt to have several defined pore sizes.  
         [0032]     According to an embodiment of the invention the foamed layer has a defined pore transverse profile (i.e., different pore sizes in the transverse profile of the material layer). It is thus possible to selectively establish the dewatering behavior and the pressing behavior by way of the web width of the paper machine covering, as the result of which the fibrous web transverse profile can be selectively established.  
         [0033]     A film mentioned above can be produced by an extrusion method and/or a rolling method for example.  
         [0034]     Various possibilities for joining together the several material layers selected from the construction kit are conceivable.  
         [0035]     For example, it is possible for at least two of the material layers to be joined together chemically. Furthermore, it is possible for at least two of the material layers to be joined together mechanically and/or by means of a textile joining method. The different material layers of a covering according to the invention can be joined together by just one or the other ways. However, it is also possible for the material layers to be joined together not only mechanically but also by textile and chemical ways.  
         [0036]     For example, a first material layer of a covering according to the invention can be joined mechanically to a second material layer and the second material layer can be joined chemically to a third material layer. Furthermore, the third material layer can be joined by a textile joining method to a fourth material layer of this covering, with the fourth material layer being joined mechanically and chemically to a fifth material layer.  
         [0037]     According to another embodiment the chemical bond is effected by an interface-active bond. In this connection an interface-active bond is understood to be a bond resulting from vulcanizing or melting or welding (i.e., ultrasonic welding). In other words, the interfaces of the two material layers which are to be joined together are changed/activated in such a way that they bond together without a bonding medium.  
         [0038]     Another embodiment of the invention provides for the chemical bond to be effected by introducing a bonding medium. In this case the bonding medium can be an adhesive for example.  
         [0039]     Furthermore it is possible for the bonding medium itself to form a material layer between the joined material layers, in which case the bonding medium is a foamed material layer for example, which is arranged between the material layers that are joined together and bonds said material layers together.  
         [0040]     The bonding medium constructed as a separate material layer can fulfill specific functions on its own or in combination with one or more material layers. For example, by combining the bonding medium with one or more material layers it is possible to exert an advantageous influence on the properties of the covering according to the invention.  
         [0041]     If the material layers are joined together mechanically it is conceivable for them to be pressed together.  
         [0042]     If the material layers are joined together by a textile joining method it is possible for them to be sewn or pinned together.  
         [0043]     If the covering is one which is not constructed of material webs in the form of endless belts, it makes sense for the various web-shaped material layers which are stacked atop one another to be joined together, two-dimensionally, in sections that are mutually offset in machine direction so that the covering forms two end areas which complement each other in form and function and can be joined together. Through the material layers which are mutually offset in machine direction and joined together, two-dimensionally, in sections, the covering forms two end areas which complement each other in form and function and can be joined together, two-dimensionally, so that the covering is constructed in the form of an endless belt. The two-dimensional bond between the two end areas is particularly stable and durable.  
         [0044]     If the covering is constructed of several material layers arranged side by side over its width, it also makes sense for the material layers which are stacked atop one another to be mutually offset at least in sections transverse to the machine direction so that above and/or under neighboring material layers of a certain layer of the covering there is always a material layer which overlaps with both material layers arranged side by side.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0045]     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 (an) embodiment(s) of the invention taken in conjunction with the accompanying drawing(s), wherein:  
         [0046]      FIG. 1  is a detail in longitudinal section of a forming mesh according to the invention,  
         [0047]      FIG. 2  is a detail in longitudinal section of a press felt according to the invention,  
         [0048]      FIG. 3  is a detail in longitudinal section of a dryer fabric according to the invention,  
         [0049]      FIG. 4  is shows the two end areas of the forming mesh of the invention according to  FIG. 1 ,  
         [0050]      FIG. 5  is a detail in cross section of a forming mesh according to the invention,  
         [0051]      FIG. 6  is a detail in cross section of a press felt according to the invention,  
         [0052]      FIG. 7  is a detail in cross section of a dryer fabric according to the invention. 
     
    
       [0053]     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification(s) set out herein illustrate(s) one preferred embodiment of the invention, in one form, and such exemplification(s) (is)(are) not to be construed as limiting the scope of the invention in any manner.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0054]     FIGS.  1  to  4  show coverings which are produced from a construction kit of prefabricated web-shaped material layers  2 ,  3 ,  4 ,  11  and  15 . All the web-shaped material layers  2 ,  3 ,  4 ,  11  and  15  of the construction kit are formed in this embodiment as non-textile areal structures.  
         [0055]      FIG. 1  shows in longitudinal section in machine direction sections of a forming mesh  1  according to the invention. The forming mesh  1  has a paper-side web-shaped material layer  2  through which the surface of the fibrous web formed on the forming mesh is essentially influenced, and a machine-side web-shaped material layer  3  through which the wear behavior of the forming mesh  1  is essentially influenced. The machine-side material layer  3  is thus a wear-stable material layer  3 . In the embodiment in question the machine-side material layer  3  also has dimension-stabilizing properties. The machine-side material layer  3  is thus also a dimension-stable material layer  3 , as the result of which the dimension-stable and the wear-stable material layer  3  form an integral unit.  
         [0056]     Arranged between the paper-side material layer  2  and the machine-side material layer  3  is a material layer  4  influencing the liquid absorption capacity.  
         [0057]     The material layers  2  to  4  were taken from the construction kit of prefabricated web-shaped materials layers  2 ,  3 ,  4 ,  11  and  15  in order to produce the forming mesh  1  of the invention (see also  FIGS. 2 and 3 ).  
         [0058]     In the embodiment in question the material layer  2  is formed as a non-textile areal structure in the form of a penetrated film with holes  5  and is produced from a material such as PE, PET, PPS or PA. The paper-side material layer  2  is undetachably joined, two-dimensionally at the interface  7 , to the material layer  4  influencing the liquid absorption capacity by chemical ways through application of a bonding medium  72  in the form of an adhesive  72 .  
         [0059]     The material layer  4  influencing the liquid absorption capacity is formed as a foamed layer with pores  9 . In this case the pores have a defined size.  
         [0060]     In the embodiment in question the material layer  3  is formed as a non-textile areal structure in the form of a penetrated film with holes  6  and is produced from a material such as PE, PET, PPS or PA. The machine-side material layer  3  is undetachably joined, two-dimensionally at the interface  8 , to the material layer  4  influencing the liquid absorption capacity by chemical ways through application of a bonding medium  72  in the form of an adhesive  72 .  
         [0061]      FIG. 2  shows in longitudinal section in the machine direction sections of a press felt  10  according to the invention. The press felt  10  is formed by the paper-side web-shaped material layer  2  known from  FIG. 1 , the machine-side web-shaped material layer  3  known from  FIG. 1 , the material layer  4  influencing the liquid absorption capacity known from  FIG. 1 , by a material layer  11  likewise influencing the liquid absorption capacity and by an anti-rewetting material layer  15 .  
         [0062]     All the material layers  2 ,  3 ,  4 ,  11  and  15  were taken from the construction kit of prefabricated web-shaped material layers  2 ,  3 ,  4 ,  11  and  15  in order to produce the press felt  10  of the invention. The order in which the individual material layers are stacked atop one another is defined by the operating conditions for which the press felt  10  of the invention is designed.  
         [0063]     The material layer  2  is joined, at the interface  13 , to the anti-rewetting material layer  15  by chemical ways through application of a bonding medium  72  in the form of an adhesive  72 .  
         [0064]     The material layer  11  influencing the liquid absorption capacity is formed as a foamed layer with pores  12 . In this case the pores  12  have a defined size which is greater than the size of the pores  9 . The anti-rewetting material layer  15  is joined, at the interface  16 , to the material layer  11  influencing the liquid absorption capacity by chemical ways through application of a bonding medium  72  in the form of an adhesive  72 .  
         [0065]     The two material layers  4  and  11  influencing the liquid absorption capacity are undetachably joined together, two-dimensionally at the interface  14 , by chemical ways in the form of an adhesive bond  72 .  
         [0066]     The machine-side material layer  3  is undetachably joined, two-dimensionally at the interface  8 , to the material layer  4  influencing the liquid absorption capacity by chemical ways through application of a bonding medium  72  in the form of an adhesive  72 .  
         [0067]      FIG. 3  shows in longitudinal section in the machine direction sections of a dryer fabric  20  according to the invention. The dryer fabric  20  is formed from the paper-side web-shaped material  2  known from  FIGS. 1 and 2  and from the machine-side web-shaped material layer  3  known from  FIGS. 1 and 2 .  
         [0068]     The two material layers  2  and  3  are undetachably joined together, two-dimensionally at the interface  21 , by chemical ways in the form of an adhesive bond  72 .  
         [0069]      FIG. 4  shows a detail in longitudinal section in the machine direction of the forming mesh  1  of the invention in the area of the two end areas  30  and  31  of the forming mesh  1 . In the situation illustrated, the two end areas  30  and  31  are not yet brought fully into contact with each other  
         [0070]     As is evident from  FIG. 4 , the web-shaped material layers  2 ,  3  and  4  are mutually offset in machine direction and joined together, two-dimensionally, in sections. As the result, the two end areas complement each other in form and function and can be joined together two-dimensionally.  
         [0071]     FIGS.  5  to  7  show coverings which are produced from a construction kit of prefabricated web-shaped material layers  41 ,  42  and  61 .  
         [0072]      FIG. 5  shows in cross section, meaning transverse to the machine direction, sections of a forming mesh  40  according to the invention. The forming mesh  40  has a paper-side web-shaped material layer  41  through which the surface of the fibrous web formed on the forming mesh is essentially influenced, and a machine-side web-shaped material layer  42  through which the wear behavior of the forming mesh  40  is essentially influenced. The machine-side material layer  42  is thus a wear-stable material layer  42 . In the embodiment in question the paper-side  41  and machine-side material layer  42  also have dimension-stabilizing properties.  
         [0073]     The material layers  41  and  42  are formed in this embodiment as textile areal structures in the form of weave structures  41  and  42 .  
         [0074]     The weave structure  41  is formed by the warp threads  45  and the weft threads  44 , whereby each weft thread  44  passes alternately under and over a warp thread  45  in order to form a smooth weave pattern, thus creating a smooth contact area for the paper fibers.  
         [0075]     The weave structure  42  is formed by the warp threads  46  and the weft threads  47 , whereby each weft thread  47  in a repeat unit passes under two consecutive warp threads  46  and then over one warp thread  46  in order to form a particularly wear-stable weave pattern in which the highly tensioned warp threads are protected by the weft threads  47  against wear.  
         [0076]     In the embodiment in question the two weave structures  41  and  42  are joined together, two-dimensionally at the interfaces  48  and  19 , by chemical ways through a bonding medium. Here the bonding medium itself forms a foamed material layer  43 , which is arranged between the two joined weave structures  41  and  42 . The foamed material layer  43  has pores  50  with a defined size. This means that the foamed material layer  43  has the function of joining together the two weave structures  41  and  42  in addition to the function of influencing the liquid absorption capacity.  
         [0077]      FIG. 6  shows in cross section, meaning transverse to the machine direction, sections of a press felt  60  according to the invention. The press felt  60  has the machine-side weave structure  42  known from  FIG. 5  and a fleece  61  with fibers  62 .  
         [0078]     The fleece  61  and the weave structure  42  are joined together at the two interfaces  63  and  49  by the bonding medium  43  forming a material layer  43 . In the case of the press felt  60 , the bonding medium again has the function of joining together the weave structure  42  and the fleece  61  as well as the function of influencing the liquid absorption capacity of the press felt  60 .  
         [0079]      FIG. 7  shows in cross section, meaning transverse to the machine direction, sections of a dryer fabric  70  according to the invention. The dryer fabric  70  has the paper-side weave structure  41  known from  FIG. 5  and the machine-side weave structure  42  known from  FIG. 5 .  
         [0080]     The two weave structures  41  and  42  are joined together, two-dimensionally, by chemical ways through a bonding medium  71  in the form of an adhesive  71 .  
         [0081]     While this invention has been described as having a preferred design, 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.  
         [0000]     List of Reference Numerals:  
         [0000]    
       
           1  Forming mesh  
           2  Paper-side material layer  
           3  Machine-side material layer  
           4  Material layer defining the liquid adsorption capacity  
           5  Holes (paper-side material layer)  
           6  Holes (machine-side material layer)  
           7  Interface  
           8  Interface  
           9  Pores (material layer defining the liquid adsorption capacity)  
           10  Press felt  
           11  Material layer defining the liquid adsorption capacity  
           12  Pores (material layer defining the liquid adsorption capacity)  
           13  Interface  
           14  Interface  
           15  Anti-rewetting material layer  
           16  Interface  
           20  Dryer fabric  
           21  Interface  
           30  End area  
           31  End area  
           40  Forming mesh  
           41  Weave structure (paper-side material layer)  
           42  Weave structure (machine-side material layer)  
           43  Bonding medium (material layer defining the liquid adsorption capacity)  
           44  Weft thread (weave structure)  
           45  Warp thread (weave structure)  
           46  Warp thread (weave structure)  
           47  Weft thread (weave structure)  
           48  Interface  
           49  Interface  
           50  Pores (bonding medium)  
           60  Press felt  
           61  Fleece  
           62  Fibers (fleece)  
           63  Interface  
           70  Dryer fabric  
           71  Bonding medium  
           72  Adhesive

Technology Classification (CPC): 3