Abstract:
An apparatus for the manufacture of a structured fiber web including an imprinting fabric, a first pressure field device, a second pressure field device and a drying cylinder. The fiber web is formed and carried on the imprinting fabric with an initial dry content of less than 35%. The first pressure field device applies a first pressure field to the imprinting fabric and the fiber web, thereby pressing the fiber web onto the imprinting fabric, thereby pre-imprinting the fiber web. The second pressure field device applies a second pressure field to the imprinting fabric in the fiber web, thereby again pressing the fiber web onto the imprinting fabric, drying the fiber web and fixing a three-dimensional surface structure in the fiber web. The drying cylinder has the fiber web delivered thereto by the imprinting fabric.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This is a continuation of PCT Application No. PCT/EP02/05808, entitled “METHOD AND DEVICE FOR PRODUCING A FIBRE STRIP PROVIDED WITH A THREE-DIMENSIONAL SURFACE STRUCTURE”, filed May 27, 2002. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a method and to an apparatus for the manufacture of a fiber web, and, more particularly, to a method and an apparatus for the manufacture of a tissue web or a hygienic paper web, provided with a three-dimensional paper structure. 
   2. Description of the Related Art 
   The imprinting of a three-dimensional structure into the surface of a paper web, in particular of a tissue web or of a hand tissue, is known, see, for example, WO 99/47749 and WO 01/18307. It is further known that a very good paper quality can be achieved by a so-called throughflow air drying (TAD=through air drying). It is, however, disadvantageous that the use of TAD dryers is very complex and correspondingly expensive. 
   What is needed in the art is a simple, more economical way of providing a high quality structural tissue. 
   SUMMARY OF THE INVENTION 
   The present invention provides an improved method and an improved apparatus to form a high quality structured tissue in an economic and correspondingly cost-favorable manner, without the use of a larger TAD drying apparatus. The expected quality level is achieved with respect to the water retention capability, the water absorption speed and the volume (bulk), etc. 
   In accordance with one embodiment the present invention, a method is disclosed for the manufacture of a fiber web, specifically a tissue web or a hygienic paper web, with a three-dimensional surface structure. The fiber web is pressed, for example by vacuum drawing it, onto an imprinting fabric at a dry content &lt;35% by way of a first pressure field. The web is thereby pre-imprinted and is then subsequently pressed onto an imprinting fabric a further time by way of a further pressure field for the further dewatering and drying of the web in order to fix the three-dimensional surface structure and the strength. 
   A sustainable three-dimensional surface structure is produced in the relevant fiber web, which remains present in the desired manner in the web, after the drying process. The use of a complex and correspondingly expensive TAD method is no longer required. In particular, a sustainable surface structure of, for example, a tissue web or a hygienic paper web can now be produced after the forming region, or forming zone, even without a TAD drying device. 
   An imprinting screen or an imprinting membrane is used as the imprinting band or structured band also, respectively known as “imprinting fabric” and “structured fabric”. The fiber web is generally pre-imprinted after the forming zone. 
   It is often an advantage for the fiber web to be formed on the imprinting fabric that is used for the pre-imprinting. The fiber web can also be transferred to the imprinting fabric used for the preimprinting. 
   Another embodiment of the method of the present invention is characterized in that at least three throughflow apparatuses are utilized and they are arranged in series in the web running direction. In the region of each throughflow apparatus the fiber web is exposed to a respective throughflow, in particular to an air throughflow, with the throughflow directions, as they relate to the fiber web, being at least partly different or opposite to one another in the different throughflow apparatuses. In particular at least three throughflow apparatuses are used in which the throughflow direction of at least one throughflow apparatus differs, with respect to the web, from the throughflow direction of the other throughflow apparatuses, which may be located on an upper side or lower side of the web. 
   In this embodiment each throughflow apparatus includes a suction device. Alternatively, at least one of the throughflow apparatuses may include a suction device and at least one of the throughflow apparatuses may include an air press. For example, in the web running direction, a first throughflow apparatus can include a suction device, a second throughflow apparatus can include an air press and a third throughflow apparatus can again include a suction device. 
   A respective suction device can in particular include a suction roll, a suction box and/or the like in each case. 
   Advantageously, at least one suction device is used in which the pressure difference (Δp) lies in a range of from approximately 0.2 up to approximately 0.4 bar. The temperature is preferably &lt;220° C., in particular ≦180° C. and preferably ≦150° C. The airflow speed through the fiber web is preferably less than ≦15 m/s, particularly with very fine clothings. The result is a much lower energy requirement and a much lower complexity of the technical plant than with the conventional TAD process. The dwell time of the fiber web in the suction zone is advantageously ≦0.5 s, in particular ≦0.4 s and preferably ≦0.3 s. 
   In accordance with another embodiment of the present invention, at least the first pressure field is produced by way of a suction element arranged on the side of the imprinting fabric remote from the fiber web in order to suck the fiber web into the surface structure of the imprinting fabric. In particular a so-called wet suction box can be used as the suction element. 
   It is also of advantage for the fiber web to be further pressed gently in the pressure field, preferably over a path extending in the web running direction. 
   The further pressure field is produced by way of a press nip. To effect a pressing of the web, which is as gentle as possible, this press nip can be produced, for example, between a drying cylinder and a counter element. The fiber web is guided through the press nip and is in contact with the surface of the drying cylinder on one side and the other side is in contact with the imprinting fabric. In particular, a so-called Yankee cylinder can be used as the drying cylinder. A shoe press unit, which includes a flexible fabric guided over a shoe press in the region of the press nip, can be used as a counter element cooperating with the drying cylinder. A shoe press roll, provided with a flexible roll jacket, is preferably used as the shoe press unit in this process. 
   Advantageously, a soft fabric or a clothing with fine pores and a capillary effect (capillary fabric), in particular felt, is provided inside the loop of the imprinting fabric to guide the web through the press nip, thereby producing the further pressure field. The soft felt can, for example, be a felt with a foamed layer, which as will be explained in more detail below, contributes to the dewatering of the fiber web, due to its capillary effect. 
   Another practical embodiment of the method of the present invention is characterized in that the pre-imprinted fiber web is dried on a drying or a Yankee cylinder, the fiber web is subsequently creped and/or wound up. 
   In accordance with one of the embodiments of the method in accordance with the present invention, the dry content at which the fiber web is pre-imprinted, and/or the dry content at which the three-dimensional surface structure is fixed, is selected to be &lt;35%, preferably &lt;30% and more preferably &lt;25%. In this process the water retention capability and the bulk is thus sustainably increased, which means that the desired imprint is still present even on the use of the end product, such as the tissue or hygienic paper web. In particular, the advantage of a higher water retention capability for a hand towel tissue or a paper towel is apparent in the use of the respective end product. 
   In accordance with one of the embodiments of the method in accordance with the present invention, a device subject to suction is used between the suction element that produces the first pressure field and the press nip that produces the further pressure field. The fiber web is guided, together with an imprinting fabric, over both the device subject to suction and through the press nip. It is advantageous for the device subject to suction, to have a curved surface, and for the fiber web and the imprinting fabric to be guided over this curved surface. A suction roll can, for example, be used as the device subject to suction. 
   A felt is expediently guided through the press nip between the imprinting fabric and the flexible fabric of the shoe press unit. 
   In specific cases, it is advantageous for the felt, which is particularly soft, to be guided over the device subject to suction. The suction effect of the device subject to suction is correspondingly reduced in this process, a hood standing under overpressure is associated with it in order to support the underpressure effect of the device subject to suction. 
   Further advantages result from the relatively long common guidance of the felt and of the imprinting fabric, since the capillary effect of the felt is utilized for the dewatering of the fiber web over the longer path. 
   The felt can, for example, be conditioned by way of a suction device, in particular by a suction box, before it is joined with the imprinting fabric to support the fiber web. In particular the dry content of the felt can be increased and the felt can be cleaned by appropriate conditioning. 
   The imprinting fabric is guided over the suction element, or over the wet suction box, prior to the device subject to suction, i.e. prior to the suction roll, in order to suck the fiber web into the three-dimensional surface structure of the imprinting fabric and thus to imprint this structure onto the fiber web. At the same time, the respective suction element brings about a corresponding increase in dry content. 
   In accordance with another embodiment of the method in accordance with the present invention, the felt is joined with the imprinting fabric supporting the fiber web, after the web passes the device subject to suction. The device subject to suction therefore does not have the felt wrapped around it, whereby the suction effect of this device is increased and the dry content is increased accordingly. The wet imprinting effect (wet molding effect) is maintained by the gentle dewatering of the so-called TissueFlex process, which, in contrast to a shoe press roll, works at a lower pressure and with a longer dwell time. 
   It is also advantageous for the length of the press nip of the shoe press that includes the drying cylinder and the shoe press unit, in the web running direction, to be larger than a value of approximately 80 mm. Additionally, the shoe press is designed such that a pressure profile results over the press nip length having a maximum pressing pressure, which is lower than or equal to a value of approximately 2.5 MPa. A gentle pressing is thus ensured, which avoids a smoothing out of the structure produced in the fiber web. As previously discussed, a suction roll, with which a pressure hood is associated, can be used between the suction element producing the first pressure field and the press nip. 
   In accordance with another embodiment of the method in accordance with the present invention, at least one dewatering screen with zonally different screen permeability is used in the forming zone. The respective dewatering screen can be provided as an external screen. This is in particular an advantage in the manufacture of hand towel tissue. The screen produces a fine structure, which increases the water absorption speed and which brings about an increased water retention capability in conjunction with the imprinting. 
   It is an advantage for a former to have two peripheral dewatering fabrics, which run together while forming a material inlet gap and are guided over a forming element such as a forming roll and for a dewatering screen, with zonally different screen permeability. The dewatering fabrics can be used as an external fabric that does not come into contact with the forming element and as an internal fabric. An imprinting fabric can be used as the internal fabric and a dewatering screen with zonally different screen permeability can be used as the external fabric in this process. It is, for example, also possible for the fiber web to be passed from the internal fabric to an imprinting fabric. 
   During wet molding in a tissue machine, that utilizes an imprinting fabric, it is a particular goal to achieve a desired dry content. The web can be wet molded by way of the imprinting fabric, for example, by way of a suction box prior to the press. To avoid disrupting the three-dimensional structure, which was pre-imprinted by the wet molding in the region of the wet suction box, by a shortterm high pressure in the press nip, an imprinting fabric, such as, an imprinting screen or an imprinting membrane, is guided through the press nip. The imprinting fabric is structured such that a surface portion has raised or closed zones, which are small in comparison with the surface portion of recessed zones or bores of the web and, accordingly, a smaller surface portion of the fiber web is pressed in the press nip. The smaller surface portion of raised or closed zones results in web zones of high density for strength. The larger surface portion of recessed zones or bores remains at least substantially unpressed, and results in the desired water absorbing capability and the desired bulk, such as was previously only achieved by the complex and expensive TAD drying. 
   An imprinting fabric can advantageously be used in which the surface portion of raised or closed zones are ≦40% of the surface area and preferably lies in a range from approximately 25% to approximately 30%. The imprinting fabric may have raised zones and recessed zones that result from offsets, such as, by intersection points of weft and warp threads, of a screen fabric. As already mentioned, an imprinting membrane can also be used, in which the raised and recessed zones result from bores therein. In this case, it is of advantageous that 100% of the surface except for the bore area is pressed and a higher strength results. 
   The respective imprinting fabric is guided together with the fiber web over, for example, a drying cylinder, in particular over a Yankee cylinder. A shoe press unit is used as the counter element cooperating with the drying cylinder. The length of the press nip and the pressure profile resulting over the press nip length can be selected as has previously been recited. 
   It has been shown that a water absorption capability (g H 2 O/g fibers) is higher by 50% and bulk (cm 3 /g) is higher by 100% as a result of using the method in accordance with the invention, at the same tensile strength, when an imprinting fabric is used instead of a conventional felt in the press nip prior to the creping. By creping the web, the water absorption capability can be improved by 50% and a water absorption capability of TAD hand towel quality can be achieved. 
   The improved quality of the paper results as a consequence of the lower pressure pressing of the web as a consequence of the smaller surface portion of raised zones and not by a TAD drier. The permeability of the web results by the stretching of the web into the fabric structure by way of the suction element, whereby so-called pillows are produced, which increase the water absorption capability and the bulk accordingly. A relatively complex and correspondingly expensive TAD drier is therefore no longer required for this purpose. 
   The function of the TAD drum and of the air throughflow system consists of drying the web. The appropriate dry content must be achieved in order to be able to carry out the wet molding in a conventional machine, i.e. in particular in a conventional tissue machine. 
   In contrast to the TAD system, in order to reduce the rewetting and to keep the desired dry content, in accordance with a preferred embodiment of the method of the present invention, at least one clothing with fine pores and with a capillary effect is used for the dewatering of the web and this can be e.g. a felt or a screen with a foamed layer. The foam coating is chosen such that pores result in a range from approximately 3 μm up to approximately 6 μm. The corresponding capillary effect is utilized for the dewatering. The respective clothing, such as a felt, can be provided with a special foam layer, which gives the surface very small pores whose diameter lie in the range of from approximately 3 μm up to approximately 6 μm. The air permeability of this clothing is very low. The natural capillary effect is utilized for the dewatering of the web while it is in contact with the clothing. 
   A clothing with fine pores, such as a screen or a felt with a foamed layer, is guided together with an imprinting fabric and a fiber web lying therebetween about a suction roll, with the clothing with fine pores preferably being in contact with the suction roll. The clothing with fine pores can, wrap around a suction roll with a diameter from approximately 2 to 3 m, or around a plurality of suction rolls with smaller diameters, preferably around suction rolls with a diameter in each case of, approximately 2 m. The dwell time of the web in the region of the suction rolls or should be longer than approximately 0.15 sec. and shorter than approximately 0.40 sec. 
   The respective suction roll can be acted on by a vacuum on its lower side or a suction roll with associated siphon extraction can be used. The water can also be centrifuged into a gutter by centrifugal force, in particular with a lower diameter roll. 
   Dewatering utilizing the capillary effect is described in U.S. Pat. No. 5,701,682. The respective capillary element is, however, part of the suction roll in the present invention. The use of a clothing with fine pores and with a capillary effect results in the following advantages in comparison with a roll:
         better cleaning   easier replacement   cheaper   simpler water removal from the roll since the roll jacket is more open than a foamed jacket.       

   Despite the utilization of the capillary effect for dewatering, a hood standing under overpressure can be associated with the device subject to suction in order to support the underpressure effect of the device subject to suction. 
   In accordance with a further embodiment of the method in accordance with the present invention, the fiber web is guided, together with an imprinting fabric for the expulsion of water by means of gas pressure, at least once, preferably twice, through a pressure space. The pressure space is bounded by at least four rolls arranged in parallel and into which a gas under pressure is introduced. The fiber web is guided through the pressure space together with the imprinting fabric and a membrane. The basic principle of such a displacement press, in which the water in the fiber web is displaced by air, is described in German Patent DE 199 46 972. 
   In accordance with another embodiment of the method in accordance with the present invention, a vacuum dewatering of the fiber web takes place in which the pressure difference (Δp) is ≧0.1 bar, preferably ≧0.2 bar and more preferably ≧0.3 bar. The pressure difference (Δp) can in particular lie in a range from approximately 0.2 bar up to approximately 0.4 bar. In contrast to the conventional TAD method, an open surface of approximately 20% is advantageously provided. A clothing with fine pores, such as a screen or a felt with a foamed layer, is used for the vacuum dewatering. The open surface in this process is, however, preferably very small such that a very small air volume flow results. 
   In accordance with still another embodiment of the method in accordance with the present invention, the vacuum dewatering takes place such that an air volume flow ≦50 m 3 /m 2 ·min, in particular ≦20 m 3 /m 2 ·min, in particular ≦5 m 3 /m 2 ·min and preferably ≦1 m 3 /m 2 ·min (to practically zero m 3 /m 2 ·min) results. 
   A corresponding “Spectra” membrane, which can be used for vacuum dewatering, allowing an airflow of 15 m/s so a higher vacuum is needed. 
   The apparatus in accordance with another embodiment of the present invention for the manufacture of a fiber web, in particular a tissue web or a hygienic paper web, provided with a three-dimensional surface structure is accordingly characterized in that the fiber web is pressed e.g. by suction onto an imprinting fabric at a dry content &lt;35% by way of a first pressure field. The web being thereby pre-imprinted and subsequently pressed onto an imprinting fabric a further time by way of a further pressure field for further dewatering and drying in order to fix the three-dimensional surface structure and the strength thereof. 
   The invention can in particular be used with Crescent Formers, Duo Formers, C Wrap Formers, S Wrap Formers and in the manufacture of multi-layer and multi-ply tissue. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     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: 
       FIG. 1  is a schematic partial representation of an embodiment of an apparatus for the manufacture of a fiber web provided with a three-dimensional surface structure; 
       FIG. 2  is a schematic partial representation of a modified embodiment of the apparatus in which the felt is guided over the device not subject to suction; 
       FIG. 3  is a schematic partial representation of another embodiment of an apparatus for the manufacture of a fiber web provided with a three-dimensional surface structure with a dewatering apparatus additionally provided in which the capillary effect of a clothing with fine pores is utilized for the dewatering; 
       FIG. 4  is a schematic partial representation of a further embodiment of an apparatus for the manufacture of a fiber web provided with a three-dimensional surface structure with a dewatering apparatus additionally provided in which the capillary effect of a clothing with fine pores, is utilized for the dewatering; 
       FIG. 5  is a schematic partial representation of another embodiment of an apparatus for the manufacture of a fiber web provided with a three-dimensional surface structure in which a displacement press is additionally provided; 
       FIG. 6  is a schematic partial representation of an imprinting fabric used in the apparatus of  FIGS. 1-5  with a smaller surface portion of raised zones in comparison with the surface portion of recessed zones; and 
       FIG. 7  is a schematic section of a press nip through which the imprinting fabric shown in  FIG. 6  is guided together with the fiber web and with a felt. 
   

   Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate one preferred embodiment of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the drawings, and more particularly to  FIG. 1  there is shown a schematic partial representation of an apparatus  10  for the manufacture of a fiber web  12  provided with a three-dimensional surface structure, which can in particular be a paper web and preferably a tissue web or a hygienic paper web. 
   Fiber web  12  is pressed, e.g. sucked, onto an imprinting fabric  14 , also known as a structured fabric  14 , at a dry content &lt;35% by way of a first pressure field I and is thereby pre-imprinted. Fabric web  12  is subsequently pressed once again onto imprinting fabric  14  by way of a further pressure field II, for the further dewatering and drying of web  12  in order to fix the three-dimensional surface structure and the strength. In particular, an imprinting screen can be provided as imprinting fabric  14 . 
   In one embodiment of the present invention, imprinting fabric  14  is provided for the imprinting and for the fixing of the surface structure. 
   First pressure field I is produced by way of a suction element  16  arranged on the side of imprinting fabric  14  remote from fiber web  12 . Fiber web  12  is sucked into the surface structure of imprinting fabric  14 . Suction element  16  can in particular be embodied as a suction box  16  or as a wet suction box  16 . 
   In further pressure field II, fiber web  12  is pressed, preferably gently, and in particular, over a path extendeding in a web running direction L. Further pressure field II is produced by way of a press nip  18 , which is formed between a drying cylinder  20  and a counter element  22 . Fiber web  12  is guided through press nip  18  and is in contact with surface  20 ′ of drying cylinder  20 . Web  12  contacts imprinting fabric  14  on its other side. 
   Specifically, a Yankee cylinder can be provided as drying cylinder  20 . 
   A shoe press unit  22 , which includes a flexible fabric  26  guided over a press shoe  24 , in the region of press nip  18 , can preferably be provided as a counter element  22  cooperating with drying cylinder  20 . A shoe press roll with a flexible roll jacket  26  is provided as shoe press unit  22 . Press nip  18  extends in web running direction L, whereby a relatively gentle pressing of fiber web  12  is achieved. 
   A fabric  28 , preferably a soft fabric, or a clothing with fine pores and with a capillary effect (capillary fabric), in particular a soft felt or a soft foamed felt, can be guided through press nip  18 , inside the loop of imprinting fabric  14 . This soft fabric  28  or clothing  28  with fine pores runs between imprinting fabric  14  and flexible fabric  26  of shoe press unit  22 . 
   Fiber web  12  can be dried on drying cylinder  20 , such as, for example, on a Yankee cylinder. Fiber web  12  can moreover be creped. Web  12  can be wound up by an appropriate device. 
   The dry content at which fiber web  12  is pre-imprinted and/or the dry content at which the three-dimensional surface structure is fixed is, as already mentioned, &lt;35% and preferably be &lt;30 and more preferably &lt;25. 
   A device subject to suction  30 , which can in particular be a suction roll  30 , is provided between suction element  16  and press nip  18 . Fiber web  12  is guided together with imprinting fabric  14  both over the device subject to suction  30  and through press nip  18 . Clothing  28  with fine pores such as felt  28 , is guided through press nip  18  between imprinting fabric  14  and flexible fabric  26  of shoe press unit  22 . 
   Felt  28  is not only guided through press nip  18 , but also over the device subject to suction  30 . Since the suction effect of device  30  is reduced by the resistance of felt  28 , a hood standing under overpressure is associated with the device subject to suction  30  to support the underpressure effect of the device subject to suction  30 . 
   A suction device  32  such as a suction box  32 , or the like, is provided for the conditioning of felt  28 . As can be recognized with reference to  FIG. 1 , suction device  32  conditions felt  28  and is arranged in front of the device subject to suction  30  in whose region felt  28  is joined with imprinting fabric  14  that is supporting fiber web  12 . Suction device  32  is arranged in front of lower deflection roll  72 . However, generally an arrangement after lower deflection roll  72  is also possible as shown in the broken-line representation  32 ′. 
   Water is removed from fiber web  12  over a longer path by the capillary effect of felt  28  due to the relatively long common guidance of felt  28  and of imprinting fabric  14 . Felt  28  is conditioned beforehand via suction device  32 , whereby its dry content is increased and felt  28  is cleaned. 
   Imprinting fabric  14  is guided over suction element  16  in front of the device subject to suction  30 , which in addition to an increase in dry content brings about a pre-imprinting of fiber web  12 . Fiber web  12  is sucked into the three-dimensional surface structure of imprinting fabric  14  or of imprinting screen  14 , whereby the structure is imprinted onto the web. 
   Now, additionally referring to  FIG. 2 , there is shown an embodiment that differs from that in  FIG. 1 , in that felt  28  is only joined with shown in imprinting fabric  14  that supports fiber web  12  after the device subject to suction  30 . The device subject to suction  30  is therefore not wrapped around by felt  28 , whereby its suction effect is increased and the dry content of fiber web  12  is increased correspondingly. The wet molding effect is maintained by the relatively gentle dewatering of the TissueFlex process in which the pressure is lower in contrast to a conventional shoe press. 
   As in the embodiment shown in  FIG. 1 , suction device  32  is arranged in front of the lower deflection roll  72  (representation in solid lines). However, an arrangement is also possible for positioning suction device  32 ′ (broken line representation) after lower deflection roll  72 . 
   Now, additionally referring to  FIG. 3 , there is shown an embodiment of the present invention in which a dewatering apparatus  34  is added. Dewatering apparatus  34  includes a clothing  36  with fine pores having a capillary effect, which can be a felt or a screen with a foamed coating. A respective foam coating is selected such that pores result in a range of from approximately 3 μm up to approximately 6 μm. 
   Clothing  36  with fine pores is guided together with imprinting fabric  14  and fiber web  12  lying therebetween about suction roll  38 , with clothing  36  being in contact with suction roll  38 . The suction roll  38 , which is wrapped around by clothing  36 , can have a diameter of approximately 2 m up to approximately 3 m. The lower side of suction roll  38  is acted on by a vacuum. Siphon extraction can generally also be associated with suction roll  38 . The respective vacuum device is designated by “40” in  FIG. 3 . 
   At least one dewatering screen with zonally different screen permeability is provided in the forming zone. 
   A former with two peripheral dewatering fabrics  14  and  42  is provided, with internal fabric  14  simultaneously serving as the imprinting fabric  14 . Dewatering fabrics  14  and  42  run together thereby forming a material inlet gap  44  and are guided over forming element  46  such as forming roll  46 . 
   Imprinting fabric  14  is formed as the internal fabric of the former coming into contact with forming element  46 . External fabric  42  that does not come into contact with forming element  46 , serves as a dewatering screen with a zonally different screen permeability. 
   A pulp suspension is introduced into material inlet gap  44  by way of a head box  48 . A pick-up element  50  also known as partition element  50  is positioned after forming element  46  and web  12  is thereby held to imprinting fabric  14  upon the separation of dewatering fabric  42 . Suction element  16  (solid-line representation) is provided in front of device  34  with a capillary effect and fiber web  12  is pressed onto imprinting fabric  14  by it. Suction element  16  can, however, also be arranged s shown by suction element  16 ′, between device  34  and suction roll  30 . 
   A soft fabric  28  or a clothing  28  with fine pores and having a capillary effect such as felt  28 , is guided, together with fiber web  12  and imprinting fabric  14 , through press nip  18  formed between drying cylinder  20  and shoe press unit  22 . Soft fabric  28  is also guided about suction device  30 . As already mentioned, this soft fabric  28  can, for example, be a clothing  28  with fine pores having a capillary effect, such as felt  28  having a conesponding capillary effect, also known as capillary felt  28 . Felt  28  is conditioned via a suction device  32  or a so-called UHLE box. Drying cylinder  20  is a Yankee cylinder  20 . Drying hood  52  can be associated with drying cylinder  20 . 
   The dry content of fiber web  12  in front of dewatering unit  34  amounts to approximately 10% up to approximately 25%. In the region following device  34  the dry content is approximately 30% to approximately 40%. 
   Now, additionally referring to  FIG. 4 , there is shown another embodiment of the present invention that differs from  FIG. 3  in that fiber web  12  is transferred from internal fabric  54  of the former to imprinting fabric  14 . Internal fabric  54  or external fabric  42  of the former can, be a dewatering screen with zonally different screen permeability. Peripheral dewatering fabrics  42  and  54  run together thereby forming material inlet gap  44 , and they are guided over forming element  46  such as forming roll  46 . Material inlet gap  44  is loaded with stock suspension by way of head box  48 . Unlike the embodiment illustrated in  FIG. 3 , the stock suspension is, supplied from below. 
   A pick-up  50  or partition element  50  is within the loop of imprinting fabric  14  and fiber web  12  is held to imprinting fabric  14  upon the separation or internal fabric  54  of the former. 
   Suction element  16  is within the loop of imprinting fabric  14  and is arranged in front of dewatering device  34  with a capillary effect. However, suction element  16  may be arranged after device  34 . Additionally, felt  28  is not utilized in this embodiment. 
   The dry content of fiber web in the present embodiment amounts to approximately 10% up to approximately 25% in the region of pick-up element  50 , to approximately 15% up to approximately 30% in the region of dewatering device  34  and to approximately 35% up to approximately 45% in the region after device  34 . 
   Now, additionally referring to  FIG. 5  there is shown an embodiment of apparatus  10  in which a displacement press  56  is provided. Fiber web  12  is guided at least once, together with imprinting fabric  14  by way of gas pressure for the expulsion of water, through pressure space  58 , which is bounded by at least four rolls  60 ,  62 ,  64  and  66  arranged in parallel and into which a pressure gas is introduced. Fiber web  12  is guided through pressure space  58  together with imprinting fabric  14  and membrane  68 . Membrane  68  forms the internal fabric of the former, which in turn includes a forming element  46  such as a forming roll  46 , in whose region internal fabric  68  and external fabric  42  run together while forming a material inlet gap  44 , which is loaded with stock suspension by way of a head box  48 . 
   After passing air press  56 , fiber web  12  is guided, together with imprinting fabric  14 , over device subject to suction  30 , in particular over a suction roll  30 , and through press nip  18  formed between drying cylinder  20  and shoe press unit  22 . Drying hood  52  is associated with drying cylinder  20  also known as Yankee cylinder  20 . 
   First pressure field I, by which fiber web  12  is pressed onto imprinting fabric  14 , at a dry content of &lt;50% and is correspondingly pre-imprinted, is produced, by air press  56 . 
   Now, additionally referring to  FIGS. 6 and 7 , there is shown imprinting fabric  14 , in the form of an imprinting screen  14 , as illustrated in the left hand part of  FIG. 6  or an imprinting membrane  14  as illustrated in the right hand side of  FIG. 6 , guided by press nip  18  is structured such that a smaller surface portion of raised or closed zones  68  results for imprinting fabric  14  in comparison with the surface portion of recessed zone or bores  74  and a smaller surface portion of fiber web  12  is accordingly pressed in press nip  18 . The surface portion of raised or closed zones  68  is ≦40% and can preferably lie in a range from approximately 25% to approximately 30%. 
   Raised zones  68  and the recessed zones can result, for example, by offsets, at intersection points of weft and warp threads of a screen fabric. In the case of the press membrane illustrated in the right hand part of  FIG. 6 , a corresponding structure results by bores  74 . 
     FIG. 6  shows a schematic partial representation of a corresponding imprinting fabric  14 , embodied as an imprinting felt  14  or imprinting membrane  14 , with a smaller surface portion of raised or closed zones  68  in comparison with the surface portion of recessed zones or bores  74 . 
   A thickness d of imprinting membrane  14  is shown in the right hand part of  FIG. 6  and can amount to approximately 1 mm up to approximately 3 mm. The open surface can in particular be larger than 50% and preferably larger than 60% and more preferably lie in a region from approximately 70% up to approximately 75%. Membrane  14  consists of a material resistant to the fiber chemistry and can, for example, consist of polyester. 
     FIG. 7  shows a schematic section through press nip  18  with imprinting fabric  14  guided together with fiber web  12  and felt  28 . Soft fabric  28  is in contact with flexible fabric  26  of shoe press unit which is guided in the region of press nip  18  over press shoe  24  by which a desired pressing force can be applied. Fiber web  12  contacts drying cylinder  20 , preferably a Yankee cylinder. Pressing zones  70  result as a consequence of raised zones  68  of fabric  14 . Fiber web  12  is already imprinted in front of nip  18 , as can be recognized with reference to  FIG. 7 , wherein it already contacts imprinting fabric  14  before entering the nip  18 . 
   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. 
   REFERENCE NUMERAL LIST 
   
       
         10  apparatus 
         12  fiber web 
         14  imprinting fabric 
         16  suction element 
         18  press nip 
         20  drying cylinder, Yankee cylinder 
         20 ′ surface 
         22  counter element, shoe press unit 
         24  press shoe 
         26  flexible fabric, flexible roll jacket 
         28  soft fabric or clothing with fine pores and with a capillary effect, soft felt 
         30  device subject to suction, suction roll 
         32  suction device, suction roll 
         34  dewatering device with capillary effect 
         36  clothing with fine pores with capillary effect, felt with foamed layer 
         38  large suction roll 
         40  vacuum, siphon extraction 
         42  dewatering fabric 
         44  material inlet gap 
         46  forming element, forming roll 
         48  head box 
         50  pick-up or partition element 
         52  drying hood 
         54  internal dewatering screen 
         56  air press 
         58  pressure space 
         60  roll 
         62  roll 
         64  roll 
         66  roll 
         68  raised zones 
         70  pressing zones 
         72  deflection roll 
         74  bores 
       d thickness 
       L web running direction 
       I first pressure field 
       II further pressure field