Abstract:
A method and device for the winding up of a moving web of paper (9) on a reel spool (11), as large a part as possible of the developing wound roll (12) having a high degree of winding hardness (WH), characterized by the fact that a relatively soft intermediate layer is formed between the wound roll (12) of high winding hardness and the winding core (11). This is achieved in the manner that, during a short initial phase of the winding process, it is ensured that the winding hardness (WH) is relatively slight in the innermost layers of the wound roll (12), whereupon an immediate transition to a relatively high winding hardness (WH) is effected which is being substantially maintained during the rest of the winding-up process. Alternately, the relatively soft intermediate layer can also be created in the manner that the reel spool (11A-11D) has a soft covering (41, 42, 43, 44, 45, 46, 47) on a metal reel spool body (40).

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a method for continuously winding up of a moving web in a winding machine for developing a soft intermediate layer between the winding core and the wound roll which has a high hardness. The invention furthermore relates to a device (winding machine) which is suitable for carrying out the method. Such a winding machine can either be a pure winding machine for webs of machine width or part of a roll cutting machine. 
     A winding machine is known, for instance, from German Patent DE PS 40 07 329 C2 or DE 44 01 959 A1. Another winding machine is described in European Patent Application EP 04 83 092 A1. Such a winding machine generally form the end section of a paper making machine or also of an off-line coating machines in order to bring the web of paper resulting there into the forms of a wound roll. During this process the paper web is wound onto a reel spool over its entire width. The reel spool is a roll-shaped winding core the diameter of which can be more than 0.6 m in the case of modern wide paper machines. For supporting the wound roll developing on the reel spool, the reel spool has bearing journals at its two ends by means of which journals it rests, for instance, on horizontal rails. 
     In other winding machines which, as a rule, are part of a roll cutter (see DE 38 32 601 and DE 32 21 929), longitudinally cut partial paper webs are wound onto sleeves. The length of each sleeve corresponds to the width of the corresponding partial paper web. The developing wound rolls are supported by at least one carrier roll; or a bed. For instance, a winding bed is formed of two carrier rolls or there are two winding beds formed of three carrier rolls. In addition, guide stands can be present and, a clamping head on each guide stand engaging into the corresponding sleeve. 
     The winding process is extremely important in paper making since at times there is the danger that paper which was up to that point produced without defects becomes so impaired upon winding that parts of a wound roll cannot be sold. The winding defects include so-called shiners, folds and tears. They are predominantly caused due to the fact that it is desired to create wound rolls of the greatest possible diameter and correspondingly high weight. 
     These winding defects are presumably produced as follows. When the paper web is being wound onto a reel spool and the wound roll has reached about 60 to 90% of its complete diameter, the high weight forces cause relative displacements of several layers of paper with respect to each other so that defective places result due to the sliding friction between the paper layers. Such defects occur mainly in the core region of the wound roll and therefore approximately in the region up to 25% of the layer thickness wound onto the reel spool. When a complete wound roll is later on unwound and these defective places become visible, the remaining paper web is cut off and becomes waste. For this reason, time and again there is an undesired loss due to waste. 
     Numerous theories exist as to how one can produce a wound roll which is free of defects. One theory, for instance, states that the winding hardness is to drop from a high initial value to a lower end value (see for instance DE 40 07 329 C2). It is the object of this method to wind the core region of the wound roll from the very start so tightly onto the reel spool that it is stiffened by the paper layers and this avoids the defective places which result for instance from sagging of the reel spool. This, however, may overstretch the web, possibly even tear it, and thus become useless. It has also been attempted to solve this problem by using reel spools of very high flexural stiffness (i.e. having a particularly large diameter), but frequently without success. 
     In accordance with JP-A-4-89746, a relatively slight winding hardness is produced at the start; then, it gradually increases to a maximum value at which the winding is finally completed. 
     In order to influence winding hardness, two parameters are available: 
     1. The web tension, i.e. the longitudinal tension with which a paper web travels onto the wound roll. 
     2. The line pressure, i.e. the force prevailing during the winding process in the nip which exists between a roll and the wound roll and through which the paper web travels. 
     The web tension is produced in different ways, depending on the design of the winding machine. In the case of a winding machine having a Pope-type reel, a drive for said Pope-type reel generally runs slightly faster than the drives of the web guide rolls in front of the Pope-type reel. In this way, the web tension is built up which, due to the static friction on the Pope-type reel, is then retained (at least to a substantial extent) up into the wound roll. 
     If the winding up of a web takes place without a Pope-type reel then, due to the introduction of a torque into the reel spool (central drive), the web tension is built up by a slightly higher circumferential winding speed as compared with the speed of the web. 
     There is also conceivable a combination of the above-mentioned methods or a build-up of tension solely between the drive of the Pope-type reel and the central drive of the reel spool. 
     Upon application of the above-described line pressure, the radius of the wound roll at the pressure point (&#34;nip&#34;) is locally less than the radius outside the pressure point. Upon leaving the pressure point, the paper web thus experiences a longitudinal tension which increases the winding hardness. Of course, also in this case combinations with the above-described parameters are conceivable. 
     SUMMARY OF THE INVENTION 
     It is the object of the invention to develop a method for the continuous winding up of a moving web in which the portion of unsalable paper, cardboard, sheet or the like resulting from defects upon the winding, is smaller than in the case of the known methods. 
     This object is achieved by forming a relatively soft intermediate layer between the wound roll which is of high winding hardness and the winding core within. 
     It was found that the problem of the above-mentioned defects cannot be eliminated by a further increase in the winding hardness. In accordance with the invention, an entirely different method is employed for solving the problem: a relatively soft intermediate layer is formed--either in the region of the innermost layers of the developing wound roll or on the shell of the winding core (preferably a reel spool)--and it is furthermore ensured that the greatest possible part of the developing wound roll is formed with the greatest possible winding hardness directly on the soft intermediate layer or at the smallest possible radial distance therefrom. 
     This solution can be realized in different ways: 
     A) The formation of a soft intermediate layer &#34;in the region of the innermost layers of the wound roll&#34; means, in other words, that one deliberately creates a weak area in the core of the wound roll in which relative movements between adjacent paper layers can take place unimpeded. The following has surprisingly been found. If only the innermost layers of the wound roll, i.e. for instance the web layers (comprising at most about 5% of the total layer thickness) produced directly on the winding core (reel spool, winding sleeve or the like), are wound relatively softly, and if one thereupon immediately and as quickly as possible continues to wind with the previously customary high winding hardness, then &#34;desired sliding places&#34; result in the core which avoids further sliding places and thus further defective places developing in the constantly growing wound roll. There is thus available a substantially greater part of marketable web material than previously. 
     B) The same or at least a similarly good result is obtained if, by using a winding core (preferably a reel spool) provided with a soft covering, one sees to it that relative movements can occur between a generally hard wound roll and the hard metal body of the reel spool. In this case, therefore, the &#34;soft intermediate layer&#34; is part of the winding core, preferably the reel spool. 
     In accordance with U.S. Pat. No. 5,265,812 it has already been attempted to solve the above-described problem by providing the reel spool with a rubber or polyurethane covering (without indication of more precise details with regard to the properties of the covering) or by the reel spool having a double shell, wherein the outer shell is connected to the inner shell only at the so-called Bessel points. (This design causes unusually high manufacturing costs). 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings indicate various embodiments of the invention. 
     FIG. 1 shows in a diagrammatical lateral view a Pope-type reel winding machine (a so-called Pope roll). 
     FIG. 2 shows diagrammatically a roll cutter. 
     FIG. 3 is a diagram which indicates by way of example the desired profile of the winding hardness WH plotted over the web layer thickness SD wound onto a winding core. 
     FIGS. 4 to 7 show different reel spool designs. 
     FIGS. 8 to 10 show possible variants of the winding machine shown in FIG. 1. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In accordance with FIG. 1, the arriving paper web 9 first travels through a nip between web tension rollers 8, then partially wraps around a Pope-type reel 10 and is then wound onto a reel spool 11, producing a wound roll 12. Longitudinal rails 13 serve to support the reel spool 11 with the wound roll 12. By means of levers 7 and a lift device 7a, the reel spool with the wound roll can be pressed against the Pope-type reel 10. As a result, an adjustable line pressure is produced between Pope-type roll and wound reel. A control device 6 determines (via a control line 6a) the degree of the line pressure and furthermore via control lines 6b, 6c and 6d, the drives M for the tension rolls 8 and/or the Pope-type reel 10 and/or the reel spool 11. The control takes place, among other things, as a function of the increasing weight or the increasing diameter of the wound roll 12 respectively, for instance by means of a measuring line 6e. 
     The device described in FIG. 1 makes it possible so to vary the line pressure prevailing between the Pope-type reel 10 and the growing wound roll 12 that it will be relatively small during a relatively brief initial phase of the winding process and will then be increased rapidly. In addition or as an alternative, the so-called web tension can be varied, this being the web tension in the direction of travel of the web which is set in the paper web 9 by means of the drives. A given web tension can be set, for instance, by a slight difference in speed between the Pope-type reel 10 and the tension rollers 8 or another web guide device not shown (for instance, dry section or glazing rollers). If the reel spool 11, as shown, is provided with a so-called central drive, then a small difference in speed can also be set between the wound roll 12 and the Pope-type reel 10. There is the possibility in all cases to briefly set the web tension during the initial phase of each new winding process at a relatively small value, it being rapidly increased thereafter. During this initial phase (also already during the so-called reel spool change), the new reel spool 110 is preferably already on the rails 13. For this, the almost completed wound roll 12 is removed somewhat from the Pope-type reel 10. Then the levers 7 are immediately applied against the new reel spool 110 so as to be able from the start to commence with the control of the line pressure to be described. 
     The above-described varying of the line pressure and/or of the web tension, assures that the winding hardness WH in each newly produced wound roll according to FIG. 3 will be relatively slight during a brief initial phase of the winding process but will thereafter be increased very rapidly to a relatively high value. The winding hardness WH can thereafter be reduced again very gradually with increasing web layer thickness SD or be maintained essentially constant or else be gradually increased further, depending on the requirements of the individual case or the type of paper. 
     A similar profile of winding hardness can be obtained upon the winding up of a paper web 9 in a roll cutter according to FIG. 2. In that case, the paper web 9 is unwound from an existing wound roll 12a having a reel spool 11a. The web travels over guide rolls 23, 24 and through a longitudinal cutting device 25 onto a first carrier roll 1 which, together with a second carrier roll 2, forms a winding bed for the developing new wound rolls 12&#39;. 
     There are also indicated diagrammatically a web guide 26 as web draw-in aid and a compressed air box 27 having a blower 28 for forming a compressed air cushion between the carrier rolls 1, 2 and the wound roll 12&#39;. That air cushion serves to reduce the bearing load of the wound roll on the carrier rolls when the diameter of the wound roll 12&#39; exceeds a given value. There can furthermore be noted a load roller 37 by which the still small wound roll can be pressed (by means of a pressing device 38) against the carrier rolls 1, 2. A control device 20 receives signals from a desired value transmitter 29 with respect to the amount of the desired operating speed and via the line 35 a measurement value concerning the instantaneous diameter of the wound roll 12&#39;. The control device 20 controls, via the lines 30 to 34, the operating speeds of the unwinding station (wound roll 12a), the guide rolls 23, 24 and the carrier rolls 1, 2 and also, via the line 36, the amount of the force exerted by the load roller 37 on the wound roll 12&#39;. For obtaining the winding hardness profile according to FIG. 3 and at the beginning of each winding process, one either briefly reduces the brake moment at the unwinding station (wound roll 12a) and/or one briefly reduces the drive moment at the carrier rolls 1, 2 relative to the other drives so as to thereby influence the web tension. Alternatively, or in addition, one can briefly reduce the pressing pressure (at 38) at the beginning of the winding process. Also in addition or alternatively, one can temporarily introduce a brake moment or a relieving force into the sleeves 11&#39;. This is done via clamping heads (not shown) which engage into the sleeves and which are part of a guide device. The wound roll 12a of the unwinding station is advisedly supported, as long as its diameter is very large, by means of a weight relief device 39. 
     As an alternative to the measures described up to now, the result of which is shown in FIG. 3, or in addition to said measures, the reel spools 11 of the winding machine shown in FIG. 1 can be developed in accordance with one of FIGS. 4 to 7. The reel spool 11A is provided in FIG. 4 with a relatively thick and soft covering 41 which is firmly attached over its entire length to the metal body 40 of the reel spool. The covering is highly resilient and it has a rubber hardness of 50-200 P&amp;J, and preferably 100-150 P&amp;J. Another possibility is shown in FIG. 5. In that case, instead of a covering, there is provided a thin additional outer shell 42 which is attached only at its two ends to the shell of the reel spool 11B so that an annular intermediate space 43 is formed which can be acted on by a pressure medium. The pressure is variable, for instance by varying the drive M of a booster pump 44. It is advantageous in this case to increase the pressure as a function of the increasing weight of the wound roll 12 (FIG. 1). FIG. 6 shows a detail of a reel spool 11C. In that case, a soft rubber layer 45 is applied to a metal roll body 40 and a hard-rubber layer 46 is applied to the soft rubber layer. The hard rubber layer 46 can also be replaced by a thin metal jacket. In accordance with FIG. 7, the soft rubber layer can be replaced by a tube 47 which is spirally wound onto the roll body 40A and the inside of which is acted on by pressure. 
     Upon each winding process and if required, one can,--in addition to forming a relatively soft intermediate layer between the wound roll and the core--counteract the increasing weight of the wound roll at least during the second half of the winding process by means of a large-area relief device. For this purpose, various known devices can be used; see, for instance, DE 44 22 877.2 or EP 0 384 533 B1. Additional possibilities are indicated in FIGS. 8 to 10. 
     The essential parts of the winding device shown in FIG. 8 are the following: the arriving paper web 9, Pope-type reel 10, the reel spool 11, the wound roll 12, i.e., the paper web wound onto the reel spool, longitudinal rails 13 for supporting the reel spool with the wound roll, endless belt 14 for directly supporting the wound roll, and belt guide rolls 15, 16, 17. One roll 15 is mounted rigidly and driveable, and the others rest on swing levers 18, whereby the guide roll 16 can be displaced on the swing lever for tensioning the belt. A lift device 19 is for lifting the swing lever and thus for pressing the belt 14 from below against the wound roll 12. 
     When the would roll is full, it is moved away from the Pope-type reel, i.e., towards the right on the longitudinal rails 13. For this purpose, swing levers 18 and guide roll 16 are swung away. If desired, the belt 14 comes into contact with the wound roll 12 only when the latter has reached a certain size. 
     In FIG. 9 the Pope-type reel 10 assumes the function of the driveable belt guide roll 15 of FIG. 8. An additional tensioning roll 19 for the belt 14 can be displaced approximately vertically. 
     FIG. 10 is a variant of FIG. 8. The belt guide roll 16 can be swung far upward so that, if required, the belt 14 supports the wound roll 12 from the start and presses the wound roll against the Pope-type reel 10. 
     These embodiments have in common is the fact that a large area relief force is exerted on the wound roll by means of a single endless belt which extends over the width of the machine and travels over guide rolls. As a result of this measure, it can be expected that an even higher percentage of a wound roll will be available as marketable paper than solely as a result of providing a soft intermediate layer.