Abstract:
A press roll for forming a press nip with an other press roll including a rotating roll shell, a roll axle and a supporting device connected to the roll axle. The supporting device supports the rotating roll shell. An end wall is associated with the press roll. At least one supporting shoe is connected to the supporting device, the at least one supporting shoe removable from the press roll through the end wall.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to a press roll for forming a press nip with another press roll, and, more particularly to, a rotating roll shell, a roll axle and a supporting or load bearing device, which is connected to the roll axle and supports the roll shell, and also a method of changing the supporting device.  
           [0003]    2. Description of the Related Art  
           [0004]    In press rolls friction causes wear of the roll shell and supporting device occurs. In particular, changing the supporting device, which is consequently required for this reason, is generally difficult and time-consuming. Because of the restricted accessibility, particularly in machines for the production and/or finishing of fibrous webs, this often requires that the entire press roll be removed.  
           [0005]    What is needed in the art is a simple way of changing the supporting device or at least a part thereof in press rolls.  
         SUMMARY OF THE INVENTION  
         [0006]    In one form of the invention, there is at least one supporting or pressure shoe that is connected to the supporting or load bearing device and is arranged such that it can be removed from the press roll through an end wall of the press roll. The supporting or pressure shoe can be removed from the press roll easily and without great effort. All without the entire press roll having to be dismantled. Advantageously, in one embodiment of the present invention there is a supporting device that is arranged pivotally within the roll shell. This makes it possible for the supporting device to be pivoted out of the working position into a changing position, before the change. In this case, the pivoted position is characterized by improved accessibility, so that the change can be carried out more quickly and without removing the entire press roll.  
           [0007]    Depending on the type of press roll and, in particular, the type of supporting device, the supporting device is pivotable together with the roll axle or the supporting device is pivotally arranged on the roll axle.  
           [0008]    The present invention offers particular advantages in the case of press rolls whose supporting device includes a supporting shoe that is pressed against the roll shell, the pressing preferably being carried out hydraulically. The pressurized fluid is led via the roll axle to the respective supporting device. The supporting device being a plurality of supporting devices arranged axially beside one another in the press roll.  
           [0009]    In machines for the production and/or conversion of paper, board, tissue or other fibrous webs, it is advantageous, during the dewatering or calendering of the fibrous web, for the roll shell to be of a flexible design and the supporting shoe to have a concave pressing surface for forming an extended press nip. If the press roll is arranged above the other press roll of the press nip, then it is advantageous, with respect to accessibility, if the supporting device can be pivoted between 90° and 270°, preferably by about 180°. In another case, specifically when the press roll is arranged under the other press roll of the press nip, that the supporting device should be pivotable between 90° and −90°, preferably between 45° and −45°.  
           [0010]    In an advantageous development of the present invention, there is at least one supply line for supplying a hydraulic fluid to the pressure piston, for pressing the pressure shoe against the inner wall of the roll shell. There can also be a plurality of pressing pistons that can be actuated individually or jointly in the direction of the roll axle. Thus, both the central zones and the edge zones of the pressure shoe have a unit assigned to them for applying the necessary pressure.  
           [0011]    According to the present invention, the supply lines can be specially configured. For example, the supply lines are lines for a hydraulic fluid, in particular hydraulic oil, that is to say the supply lines are pressure lines. Supply lines of this type, in particular the hydraulic lines, each have a disconnection point. Quick-action couplings are preferably used as disconnection points. The disconnection points are advantageously arranged underneath the roll shell, in the vicinity of an end cover of the press roll. This ensures good accessibility.  
           [0012]    The disconnection points are configured so that the inner pipeline parts can be moved with respect to the outer. That is to say, parts arranged closer to the roll shell, can be raised or rotated. The ability to rotate is ensured, for example, by rotary couplings. By way of the rotary couplings, the tightness at the connecting point between the outer and the inner line parts is ensured. The supply lines run through the interior of a fixed axle into the interior of the press roll.  
           [0013]    The supply lines include lubricating lines, which are under hydrostatic pressure, and/or measuring lines, which belong to a hydraulic system and measure the pressure in the pressure lines for applying the pressing pressure for the pressure shoe. Likewise, lines are provided for lubricating oil.  
           [0014]    The supply lines, at least in the region in which the load bearing or supporting device carries out a rotary movement or a translational movement, are of a flexible design. For example, the supply lines may be a hose, a cable or another flexible line, in order that they can follow the movement of the supporting device. The supporting device and, in particular, the supporting shoe are always supplied with the requisite medium, for example pressurized oil.  
           [0015]    If for example, the pressure or supporting shoe has a length of 120 mm, a minimum displacement of more than 7 mm, but preferably of more than 10 to 15 mm, is provided. If the supporting shoe has a length of 270 mm, a minimum displacement of more than 10 mm, but preferably of more than 15 to 20 mm, is provided; if the supporting shoe has a length of more than 300 mm, a minimum displacement of more than 20 mm is provided. These dimensions apply relative to drying a paper web for a graphic paper, but also generally for white and brown paper.  
           [0016]    For material webs of paper and tissue, a press roll suitable to be used as a backing roll is one which has a diameter of more than 1000 mm, preferably a diameter in the range of between 1000 and 1600 mm, while the supporting shoe has a length of more than 120 mm. In the case of a press roll for use exclusively for tissue webs, the press roll has, for example, a diameter in the range of between 2500 and 5500 mm and the supporting shoe has a length of less than 150 mm.  
           [0017]    According to one embodiment of the present invention, the removal of the pressure shoe from the press roll is made easier by the fact that the spacing of the press rolls is enlarged. This is done, for example, by the spacing of the bearing walls or the bearing housings being enlarged. In this case, either the press roll containing the pressure shoe or the press roll used as a backing roll is displaced by a fixed distance from the other press roll. The movement is preferably carried out by way of one or more hydraulic cylinders.  
           [0018]    In one embodiment of the present invention, the end cover, that is to say the clamping disk, can also be dismantled. Instead of removing the entire end cover, provision is made for there to be only one removal opening at the end of the press roll, through which the supporting shoe can be removed from the press roll. In order to prepare a change of the supporting shoe, as described above, the spacing between the press roll and the press roll is enlarged. During the enlargement of the spacing, it may also be necessary for supply lines to be isolated. As such, the coupling elements that can be disconnected are arranged in the supply lines. The supporting apparatus, with the pressure shoe, is then rotated out of the operating position through a fixed angle. The pressure shoe is removed through an end opening in the press roll and through a removal opening or a cutout in the bearing wall in which the press roll is mounted. Alternatively, the cover at the end is moved to the side or removed as a whole. The supporting shoe is then moved out or pulled out in the direction of the longitudinal axis of the press roll. When the supporting shoe is replaced by another supporting shoe, the installation steps are completed in the reverse order.  
           [0019]    Some reasons for the rapid removal of a supporting shoe are for replacement due to wear, or in an adaptation of the geometry of the supporting shoe relative to production and quality requirements such as different paper grades. For instance, for specific paper qualities, the specific volume is a critical quality feature, which requires gentle dewatering, for which a longer supporting shoe with an adapted pressure profile is used.  
           [0020]    For a high production throughput, it is critical that a high dewatering performance be achieved. For this purpose, a high dewatering pressure is used to achieve a high level of dryness, so that there is little time expended on drying.  
           [0021]    Another reason for changing the supporting shoe is when the latter is damaged, which may occur at the passage of a thickening in the paper web (passage of a lump) or in the event of felt damage. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    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:  
         [0023]    [0023]FIG. 1 shows a schematic cross section through a press roll of an embodiment of the present invention;  
         [0024]    [0024]FIG. 2 shows a cross section through a press roll of another embodiment of the present invention;  
         [0025]    [0025]FIG. 3 shows a longitudinal cross section through the press roll of FIGS. 1 and 2;  
         [0026]    [0026]FIG. 4 shows a cross section through the press roll of FIG. 3;  
         [0027]    [0027]FIG. 5 shows a cross section through a press roll having a pressure shoe, which is arranged underneath a press roll serving as a backing roll;  
         [0028]    [0028]FIG. 6 shows an enlarged detail from FIG. 5; and  
         [0029]    FIGS.  7  to  10  illustrate the positioning of a press roll in various positions for the removal of the pressure shoe of the present invention. 
     
    
       [0030]    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  
       [0031]    Referring now to the drawings, and more particularly to FIGS. 1 and 2, there is illustrated a press roll  1 , and another press roll  2 , which forms a press nip for treating a material web  7 . Material web  7  may be a paper, board, tissue or another fibrous web  7 . In the case of calendering, fibrous web  7  runs through the press nip by itself. In the case of the dewatering of fibrous web  7 , at least one endlessly circulating belt is also guided through the press nip in order to pick up the water pressed out of web  7 .  
         [0032]    Press roll  1  has a flexible roll shell  3  and a roll axle  4  with a supporting device  5 . Supporting device  5  is responsible for pressing roll shell  3  toward press roll  2 . Supporting device  5  has a supporting shoe  6 , which has a concave pressing surface that forms an extended press nip.  
         [0033]    As shown in FIG. 1, press roll  1  is arranged above press roll  2  and supporting device  5  is firmly connected to roll axle  4 . Since the accessibility in this position is normally particularly restricted, roll axle  4  with supporting device  5  can be pivoted by up to 270°. In the event of a change of supporting device  5 , or a part thereof, such as supporting shoe  6 , supporting device  5  can be pivoted out of the working position into a changing position. In the changing position the accessibility to shoe  6  is substantially better. The changing position depends on the type of machine unit and also the specific configuration.  
         [0034]    As shown in FIG. 2, a press or calendering apparatus has a press roll  1  that is arranged under press roll  2 . In addition, supporting device  5 , with its supporting shoe  6 , is pivotally mounted on roll axle  4  by way of a ring  8 , so that roll axle  4  can be fixed. Here, supporting device  5  is illustrated in a changing position being rotated approximately −45°.  
         [0035]    Since the lower position of press roll  1  is normally more easily accessible, the ability to pivot supporting device  5  through a small angle provides a significant advantage. Of course, both press rolls  1  and  2  can have a pivotable supporting device  5 .  
         [0036]    Now, additionally referring to FIG. 3 there is shown a press roll  1  corresponding to the width of material web  7  from which moisture is to be removed. There is a single supporting shoe  6 , also known as a pressure shoe  6 , which is pressed against roll shell  3  by a single supporting device  5  or by a plurality of supporting devices  5 . Supporting device  5  includes a pressing element, in which there are a plurality of pressure regions  11  for pressing supporting shoe  6  against roll shell  3  and thus against press roll  2  used as the backing roll. Arranged in the edge zone of pressure shoe  6  are relief elements  12  and  13 , which have a smaller pressing area than pressure regions  11  with supporting shoe  6 , so that only a low pressure is built up in this edge region. Pressure regions  11  and relief regions  12  and  13  are jointly supplied with pressurized oil by way of a line  14 . Arranged in line  14  is a detachable connection  140 , which makes it possible, during a pivoting or a displacement movement of supporting device  5  and of supporting or pressure shoe  6  connected to the latter, to keep a load bearing element  15  that holds supporting device  5  in a fixed location while supporting device  5  is moved.  
         [0037]    Line  14  is divided into a plurality of lines  141 ,  142  and  143 , which are used to supply pressure regions  11  or relief regions  12  and  13  with pressurized oil. Pressure regions  11  are interconnected by way of connecting lines  144 . If no pressure is exerted on supporting shoe  6  by way of the hydraulic system of pressure regions  11  and relief regions  12  and  13 , supporting shoe  6  is pulled back into a position in which it is lifted off of roll shell  3  by return springs  17  and  18  formed as tension springs. Line  14 , just like supply lines  19  and  20 , runs through a stationary axle  21 . Supply lines  19  and  20  are also equipped with quickly detachable connections  190  and  200 , respectively. Roll shell  3  is clamped in lateral clamping elements  22  and  23 , which, together with roll shell  3 , are rotatably mounted in ball bearings  24  and  25 . On the outside, fixed-location end covers  26  and  27  are mounted in front of clamping elements  22  and  23 . The interior of press roll  1  is sealed off with respect to the external region by way of seals  28  and  29 .  
         [0038]    Now, additionally referring to FIG. 4, there is shown a supply line  19  that supplies lubricating and cooling oil, which is under hydrostatic pressure. The lubricating and cooling oil is supplied within press roll  1  to a distributor  30 . From distributor  30 , the oil is applied to the inner wall of roll shell  3 . It is necessary for the contact zone between press rolls  1  and  2  to be cooled, so the oil is particularly supplied there. Supply line  20  removes the oil from press roll  1  in order that it can be cooled again in a cooling apparatus (not illustrated here). Likewise, a filter is incorporated in the oil circuit. Roll shell  3  is held on press roll I in a form that has a circular cross section by shell guide bars  31  connected to load bearing element  15 .  
         [0039]    Now, additionally referring to FIGS. 5 and 6 there is illustrated another embodiment of the present invention, in which a press roll  40  with a pressure or supporting shoe  41  is arranged under press roll  42 . A material web  43 , for example a paper or a tissue web, runs between press rolls  40  and  42 . Pressure shoe  41  is pressed against material web  43  by a pressing element  44 . Pressing element  44  is raised by way of a fluid, for example hydraulic oil, supplied by line  14 , in order to press pressure shoe  41  against material web  43 . Pressure shoe  41  is replaceably arranged in load bearing element  15  in a holder  45 , which can be moved together with pressure shoe  41 . The supply of the hydraulic oil is ensured by connecting lines  14 . A lubricating oil distributor  45  applies the lubricating oil, which is supplied by line  19  to the inner wall of the roll shell  3 . As a result of the pressure of pressure shoe  41  against the inner wall of roll shell  3 , the lubricating oil runs off on the rear flank of roll shell  3 , as viewed in the direction of rotation, so that it is collected in an oil collecting container  46 . From there, after it has been filtered, it flows onto the inner wall by way of a siphon  47  in the lower region of the interior. Oil collecting container  46  and siphon  47  are connected to load bearing element  15 .  
         [0040]    Now, additionally referring to FIGS. 7-10, there is shown another embodiment of the present invention, in which a press roll  11  is arranged in a bearing housing with a bearing wall  10  and having a supporting or load bearing device  15  arranged above press roll  33  used as a backing roll, which is mounted in a bearing wall  35 . Bearing wall  35  stands on a base  36 . Supporting device  15  has a supporting shoe  16 , which, in the operating position, presses the material web against press roll  33 . The pressure or supporting shoe  16  can be drawn upward to such an extent that the supporting device  15  can be pivoted past press roll  33 .  
         [0041]    The displacement travel A needed for this purpose, which is traced upward by supporting shoe  16  in the direction of arrow B, is chosen to be sufficiently large for the necessary spacing from press roll  33 . The movement of pressure shoe  16  is achieved, for example, by way of return springs  17  and  18 . In order to facilitate or to assist the removal of pressure shoe  16 , there is additionally, on bearing wall  10 , a hydraulic device (not illustrated here) which additionally raises bearing wall  10  by a distance H.  
         [0042]    Alternatively, load bearing device  15  together with pressure shoe  16  is rotated upward by an angle α, as shown in FIG. 10. Bearing wall  10  for press roll  11  is constructed in such a way that, at this angle, it has a cutout through which pressure shoe  16  can be withdrawn from press roll  11  at the end, parallel to the longitudinal axis of press roll  11 . During replacement of supporting shoe  16  by another supporting shoe, all the steps are completed in reverse order.  
         [0043]    In addition to the possibilities discussed extensively above, within the scope of the invention there are many variants according to which pressure shoe  16  can be removed. These variants can also include, for example, cantilevered displacement of press roll  1 ,  11  or  40  on one side. As such, supporting or pressure shoe  6  or  16  can be withdrawn from the press roll when no pressing pressure is applied to it by the hydraulic fluid.  
         [0044]    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.