Abstract:
A paper, board or material web is wound in a winder of the two-drum type. Winding core ( 10 ) ends placed against each other are coupled to be on the same axis of rotation during winding by severing cuts ( 12 U,  12 N) which are formed in the ends ( 11 A,  11 B) of the winding cores ( 10 ) and which deviate from a perpendicular cutting line.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application is a divisional application of application Ser. No. 10/569,568, filed Feb. 27, 2006, which was a national stage application of International App. No. PCT/FI2004/000495, filed Aug. 24, 2004, which claimed priority on Finnish App. No. 20031218, filed Aug. 29, 2003. The disclosures of said U.S. applications are incorporated by reference herein. 
     
    
     STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    The invention relates to a method for winding a paper, board or material web on a winder of the two-drum type, and to a method for manufacturing a winding core for a winder, and a winding core for a winder. 
         [0004]    In the prior art, slitter-winders are known in which winding takes place on winding drums after the slitting of a paper, board or material (e.g. plastic, aluminum, etc.) web. In winders of the two-drum type, slit component webs are wound around a winding core, e.g. a roll core, on support of two drums or one drum and a set of drums or two sets of drums. In the following description and claims, for the sake of simplicity, the term winding drum is used when referring to a carrier drum/a set of carrier drums in a winder of the two-drum type, i.e. including the meanings of both a winding drum and a set of winding drums. In addition, in the following description the term roll core is also partly used in the general sense ‘winding core’, i.e. by the term roll core is meant a winding core that is made of paper, board, glass fibre, metal, plastic, or the like. 
         [0005]    In two-drum winders, in which narrower component webs slit with slitter blades from a web unwound from a machine reel are wound into customer rolls, the rolls are usually placed side by side on two winding drums. Because of variations in the cross-direction profiles, for example, thickness, moisture, roughness or friction, of the web to be wound, adjacent rolls are not always formed with precisely equally large diameters, in spite of the fact that precisely equally long component webs are wound into them. Owing to the different diameters of the rolls, the winding cores placed in the roll centers are displaced with the progress of winding in relation to one another so that their centers of rotation are separated and, at the same time, variations also occur in the angular speeds of the rolls. Because of this detrimental phenomenon there occurs vibration in two-drum winding, with the result that it is necessary to limit speed, i.e. to be content with a lower winding speed, which reduces the capacity of the machine and is, thus, uneconomical. 
         [0006]    The problem described above has occurred as long as winders of the two-drum type have been constructed without a shaft, i.e. inside roll cores there is no shaft that couples them together. The seriousness of the problem has, however, varied in the course of the years, because the profile of the web produced on the paper machine has improved and a limited running speed has been accepted on the slitter-winder. In recent years, the diameters of the customer rolls produced have started becoming ever larger and, at the same time, the machine widths and the winding speeds have also increased, for which reason the problem of vibration has been noticed again: even a small variation of profile in the direction of width of the web is cumulated especially during winding of thin paper grades so that faults in the shape of the rolls which arise from the web profile cause a significant vibration problem. 
         [0007]    In the winding process, a number of different phenomena are effective which attempt to shift the web rolls that are being formed in their axial direction:
       deflection of winding cylinders, i.e. winding drums,   faults in the shape of the rolls arising from uneven profile of the web, and   also the core chucks, which support the winding cores of the outermost web rolls, subject the row of rolls to axial forces when they keep the row of rolls in the desired position.       
 
         [0011]    One problem in winding is also that the length of the winding cores, for example, roll cores, changes during winding because the compression pressure caused by the winding of the web onto the roll core causes widening of the wound web and elongation of roll cores. 
         [0012]    The core chucks alone can also produce a compression force acting on the whole row of winding cores if the winding cores are excessively long: the total length of the winding cores is greater than the regulated distance between the core chucks. 
         [0013]    When a paper or board web is wound around a roll core, in two-drum or carrier belt slitting the rolls and the roll cores are in a row and they are kept in place in the axial direction by means of core chucks. If there are cross direction thickness variations in the web, the rolls will have different diameters and, consequently, the roll cores are no longer on the same axis of rotation. This readily leads to the bouncing of rolls and the running speed must be lowered. In some places the situation has been helped by disposing sleeves between the roll cores to couple the roll cores together for the time of winding. However, the use of them causes additional work and makes the separation of the rolls more difficult after the winding. 
         [0014]    One problem is that if the circumference of a roll changing in a winder is round in its outer surface but the roll core is not located at the center line, this makes converting more difficult in which the roll is again supported at the center, because in such a case the roll starts to bounce. This also causes problems in that in converting, for example, in printing houses where roll change is accomplished as a flying splice change, the alignment of the web is generally monitored based on the edge and if the roll has not been formed properly in respect of the center, there will be a displacement of the web at the splice in connection with splicing. 
         [0015]    In the course of the years, the rolls have become larger in size, diameter has increased and width has grown and, along with it, it has been necessary to make the roll cores still harder. Since during tight winding the roll cores nevertheless elongate, this elongation cumulates in the edge rolls and against the core chucks. To prevent the increase of the axial force of the roll chucks, the core chucks have been provided with flexibility but it increases the dishing of the edge rolls. Roll dishing occurs when a contracted web under tension is wound. The tension changes into a compression stress inside the roll, with the result that the web tends to become wider. This causes the rolls to push one another. The widening cumulates from the middle toward the edges. 
         [0016]    The problems described above are most difficult when winding a web that has high compressibility and a high friction coefficient. Such web grades include, for example, DIP newsprint which is recycled fiber based newsprint, and sack paper. The degree of seriousness of the problem is affected, among other things, by where the recycled paper is derived from, what kind of deinking method has been used in its cleaning and what properties the recycled paper has. 
         [0017]    With respect to the prior art, reference may be made to FI patent application  20002679 , which discloses a method and a device for winding a paper or board web and proposes an arrangement for the problems described above and, in particular, for determining the compression pressure and the position of core chucks in the winding process, in which arrangement measuring devices for measuring the position and the force of the chuck as well as machine controls for controlling the core chuck are arranged in connection with the core chuck such that the position and/or the force of the chucks is in a desired value range, i.e. within desired limits, and no harmful vibration is generated because of axial thrust forces of detrimental magnitude between the winding cores. It is stated that in this method according to the invention it is novel and inventive that in the method the winding cores are placed in a desired position and subjected to a desired compression force by means of the core chucks, the length of the row of the winding cores is determined and the compression force of at least one core chuck is regulated during winding when the length of the row of the winding cores changes to keep the compression force and/or the length of the winding core row within desired limits. 
         [0018]    With respect to the prior art, reference may also be made to FI patent No. 103103, which discloses a method in winding, wherein a number of separate rolls are formed around separate winding cores placed one after the other while supported by support members, in an attempt to solve the problems described above, in particular in connection with different vibration problems. It is stated that a new idea in this method is that, in order to reduce the friction coefficient of the winding cores, before, or at the same time as, the winding cores are placed in the winding position, the ends of the winding cores are treated with an agent that reduces the friction coefficient, or a piece of a material that has a low friction coefficient is placed at the ends of the winding cores, and/or the axial thrust force between the winding cores is lowered by passing a pressurized medium through the core chucks and allowing it to discharge from between the winding cores. 
       SUMMARY OF THE INVENTION 
       [0019]    One object of this invention is to create a novel arrangement that can be made use of with the prior art arrangements described above or as a separate system to eliminate or at least minimize the problems described above. 
         [0020]    In accordance with the invention, at least one severing cut that deviates from a perpendicular cutting line is made in the ends of winding cores to be placed in end-to-end relationship or in the ends of pieces attached to the ends of a winding core, and a mating cut for the severing cut is made in the end of a winding core, for example, a roll core which is in end-to-end relationship with it. 
         [0021]    The severing cut that deviates from a perpendicular cutting line in accordance with the invention is made either directly in the core material in the end of the winding core, i.e. the roll core, or in a separate piece attached to the end of the roll core. This severing cut can be made, for example, in connection with the sawing of the roll core by turning on a lathe, milling/cutting, grinding, heating, pressing or swaging. 
         [0022]    In accordance with the invention, a severing cut deviating from a perpendicular cutting line is formed in the ends of the winding core, or the roll core, i.e. grooves which are so placed that the ends of the roll cores to be placed in end-to-end relationship have a male and a female grooving against each other, that is, a cut that deviates from a perpendicular cutting line and a cut of its desired mating shape. In the roll cores placed against one another in the winding process, there is a male grooving at the end of one roll core and a female grooving at the end of the other roll core. When the core chucks are locked and winding is started, the roll cores are coupled to one another, whereby the roll cores remain on the same axis of rotation during winding, which means that no stepped diameter differences between the rolls can arise. Hence, the rolls also do not start to bounce. From the foregoing it also follows that between the rolls no stepped diameter differences can arise that limit the running speed. 
         [0023]    In accordance with the invention, at least one severing cut that deviates from a perpendicular cutting line is made in the end of the winding core, i.e. the roll core, but there can also be more cuts, that is, grooving is formed of at least one groove or a part of it (a diagonal cut). The depth of the grooving is advantageously 0.5-5 mm deep and thus such that it couples the roll cores together but does not prevent the rolls from being separated from one another on the floor after winding. The shape of the severing cut can be a broken line, a wavy line or another appropriate shape, for example, an oblique surface. 
         [0024]    In accordance with one advantageous additional feature of the invention, the depth of the severing cuts (male-female) which deviate from a perpendicular cutting line and are placed against each other, is formed such that they do not fully correspond to each other but the grooves of the winding cores, or roll cores, to be placed against each other are not mirror images of each other, but, instead, the grooves of one side are unequal in depth. By this means, axial play is provided between the roll cores. When the roll cores elongate during winding, this elongation disappears in the ends of the roll core because of this allowance for longitudinal yielding without it being cumulated in the edge rolls. Thus, roll dishing and the axial force of the chuck are reduced. This also provides the advantage that when the roll becomes wider during winding the sides of the roll are able to lean against one another, which leads to a more stable winding process and neater roll sides at high running speeds. The allowance for longitudinal yielding, i.e. the longitudinal yield limit in mating cuts of different depths, can be, for example, 0.5-2 mm. 
         [0025]    The invention is suitable for use in connection with all different roll core sizes and for all wound webs. It is particularly advantageous when winding a material that has high compressibility and a high friction coefficient, for example, DIP newsprint and sack paper. 
         [0026]    In the following, the invention will be described in greater detail with reference to the figures in the appended drawing, but the invention is by no means meant to be narrowly limited to the details of the figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIGS. 1A-1D  show four different alternatives for severing cut shapes of a roll core end. 
           [0028]      FIG. 2  shows further different additional alternatives. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]    In the following figures, the parts corresponding to one another have been designated by the same reference numerals. As shown in the figures, a cut  12 U that deviates from a perpendicular cutting line has been made in one end  11 A of a winding core, or a roll core  10 , which cut  12 U is placed against an end  11 B of a roll core  10 , as a mating cut  12 N, situated against it in end-to-end relationship, thereby forming, in a way, a male grooving  12 U and a female grooving  12 N, which couple the ends  11 A,  11 B of the roll cores  10  to each other such that their center lines of rotation remain on the same line during the time of winding. 
         [0030]    In the exemplifying embodiment shown in  FIG. 1A , the severing cuts  12 U,  12 N which deviate from perpendicular have been made as a broken line in which the male and female groovings  12 U,  12 N conform directly to each other, thus coupling together the ends  11 A,  11 B of the roll cores  10  placed against each other. 
         [0031]      FIG. 1B  shows an arrangement in which the severing cut shape  12 N of the end  11 A of one roll core  10  has been made deeper than the severing cut shape  12 U of the end  11 B of the other roll core  10 , which end  11 B is placed against the first-mentioned end  11 A, i.e. the female grooving  12 N has been made deeper than the male grooving  12 U, thereby providing allowance for longitudinal yielding in accordance with an advantageous embodiment, which allowance makes it possible to compensate for the elongation of the roll cores  10  that occurs during winding. 
         [0032]      FIGS. 1C and 1D  show an arrangement in which the severing cuts  12 U,  12 N in accordance with the invention have been formed into groovings  12 U,  12 N such that the main direction of the grooving  12 U in the end of at least one roll core  10  is oblique toward the center line of the roll core  10 , thereby providing more distance for yielding, i.e. when the roll cores  10  elongate during winding. 
         [0033]    The example A of  FIG. 2  shows an embodiment in which the severing cuts  12 U,  12 N used form a serrated grooving. 
         [0034]    The example B of  FIG. 2  comprises a serrated grooving  12 U,  12 N with finer teeth as compared with the example A. 
         [0035]    The example C of  FIG. 2  shows an embodiment which uses a curve-shaped severing cut as the severing cut shapes  12 U,  12 N. 
         [0036]    The example D of  FIG. 2  shows one advantageous exemplifying embodiment in which the groovings  12 U,  12 N have been accomplished by means of two grooves and two tongues, longitudinal adjustment being accomplished by means of a greater groove depth of one grooving  12 N. 
         [0037]    The example E of  FIG. 2  shows an embodiment in which the coupling of roll cores  10  to each other is accomplished by means of oblique severing cuts  12 U,  12 N. 
         [0038]    The example F of  FIG. 2  has been accomplished by means of one groove-and-tongue broken-line-shaped severing cuts  12 U,  12 N. 
         [0039]    The example G of  FIG. 2  shows an embodiment in which an oblique severing cut, i.e. an oblique surface  12 N, has been combined with one tongue-shaped cut  12 U. The examples H and I of  FIG. 2  show wavy line types of severing cuts  12 U,  12 N, which have been accomplished using one groove-and-tongue shape  12 N,  12 U placed at different locations in the ends of the roll core  10 . Of course, the wavy line may also extend over the entire area of the end cut of the roll core. 
         [0040]    The cutting lines described above and other possible cutting lines in accordance with the different embodiments of the invention, which cutting lines deviate from perpendicular, can be accomplished such that in one end  11 A of each roll core  10  there is a cut  12 U of the male type and in the other end a cut  12 N of the female type or such that roll cores  10  are used which have male cuts  12 U and female cuts  12 N, respectively, in both ends and the location of these roll cores  10  in the winder is alternated. 
         [0041]    Above, the invention has been described only with reference to some of its advantageous exemplifying embodiments, but the invention is by no means meant to be narrowly limited to the details of them.