Patent Publication Number: US-6659387-B2

Title: Peripheral rewinding machine and method for producing logs of web material

Description:
RELATED APPLICATION 
     This application is a continuation-in-part of U.S. Ser. No. 09/942,275, filed Aug. 27, 2001 now abandoned entitled “Peripheral Rewinding Machine and Method for Producing Logs of Web Material.” 
    
    
     BACKGROUND 
     The present invention relates to a peripheral rewinding machine and a related rewinding method for the production of rolls or logs of web material, such as paper and the like, on a tubular support or core. 
     In a peripheral or surface rewinding machine of the type to which the invention refers, the roll is wound around a tubular core which is set in rotation between a group of three rollers that act on the periphery of the roll being formed, and the speeds of which are kept constant and equal during the winding cycle. 
     The group of three motorized rollers forms a space of variable size so that the three rollers are always in contact with the roll being formed, as the roll increases in diameter. Two of the three rollers are placed at a fixed distance, so as to define a gap, through which the core is inserted, and in which the web material travels, whilst the third roller or pressure roller is movable to allow the diameter of the roll to increase and the roll to be expelled at the end of winding. 
     In these rewinding machines the so-called changeover stage, sometimes called cutoff and transfer, is important. That stage includes insertion of a new core in the winding space, accompanied by a special inserter, and discharge of the completed log, following severing of the web material. This severing is obtained in various ways according to the prior art, generally requiring sudden changes in the speed of two of the three winding rollers. 
     According to some known methods, the speed change of said rollers alone, which is naturally of rather a large magnitude, causes tensioning and tearing of the web of paper following nipping thereof against the roller along which it is fed, nipping which can take place by means of a new core which is inserted in the winding space. After severing of the web of paper, entry of the new core into the winding space and discharge of the formed log take place through differences in speed between the two input rollers and the two output rollers, respectively. 
     As stated previously, this method of severing the paper requires large variations in speed between the rollers, and in particular strong accelerations of the pressure roller, which cause stress on the structure of the machine. Moreover, such methods make it difficult to sever the web material along a single pre-selected perforated line to provide the completed log with exact sheet count. 
     Other systems use true cutting blades that cut the web at the end of winding and require complicated actuating mechanisms. Moreover, they are not very flexible in that they are tied to carrying out the cut on well-defined lengths of web material. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to eliminate the drawbacks of the solutions of the prior art, and therefore to provide a rewinding machine and a rewinding method that are reliable and simple to create and ensure precise cutting of the web material. 
     This object is achieved with the rewinding machine and method according to the appended independent claims. Preferred embodiments of the invention are apparent from the dependent claims. 
     Substantially, according to the invention, a blade is carried by a rotating member which is pivoted on the axis of the roller around which the web material is wound and rotates in the same direction as the roller is provided. The rotating member is actuated when the log is in the completion stage at a speed equal to or substantially similar to that of the web material, to be subsequently slowed or accelerated when it is inside the winding space, to cause tensioning and severing of the web material. Normally severing of the material takes place along a line of perforation in the web. 
     Further characteristics of the invention will be made clearer by the detailed description that follows, referring to a purely exemplary and therefore non-limiting embodiment. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The invention will be explained in conjunction with the drawings, in which 
     FIG. 1 is a schematic side view of the basic elements of the rewinding machine according to the invention; 
     FIGS. 1A to  6 A are views like that in FIG. 1, illustrating successive stages of the winding cycle according to a first embodiment of the invention; 
     FIGS. 1B to  6 B are views like that in FIG. 1, illustrating successive stages of the winding cycle according to a second embodiment of the invention. 
    
    
     DESCRIPTION OF SPECIFIC EMBODIMENT 
     With reference to said figures, for now in particular to FIG. 1, which schematically illustrates a few more elements of the machine, a brief description of said elements will be made. In the description that follows, reference will be made in the singular to the elements shown in the drawings, it nevertheless being obvious that many of them, such as the arms and levers, are disposed in pairs, at the two sides of the machine. 
     In the appended figures, W designates a web material, in particular paper, which is unwound from a large-sized roll, not shown, and, travelling in the direction of the arrow F, is suitably tensioned by rollers R 1  and R 2  and wound around a first winding roller A, to be rewound in rolls or logs  1 , of a considerably smaller diameter, around a tubular central core  2 . 
     The first winding roller A is associated with a second winding roller B, which defines therewith a gap  3 , through which the cores  2  are inserted. The width of the gap  3  is constant during operation of the machine and not greater than the diameter of the core so that the latter enters the gap with slight forcing. One of the two rollers A, B, in the example shown the first winding roller A, is supported by a mobile arm  4 , schematised in the figure, pivoted at  5 , to adjust the width of the gap  3  to the diameter of the core  2  which is used. 
     The group of three winding rollers is completed by a third roller C, also called a pressure roller, supported by an arm  6  movable around a fulcrum  7 , according to a pre-determined law of motion, to allow the roll  1  to be increased in diameter and discharged at the end of winding. The rollers A, B, and C are rotatably mounted in a frame (not shown) and may be controlled by conventional servo motors. 
     Upstream of the gap  3  a feed slide  8  is provided for the cores  2 . A core inserting device comprising idler rollers  9  is carried at the end of an arm  10  pivoted at  11 . The arm  10 , which in the appended figures has been schematised with a segment of straight line, in fact has, in a per se known manner, a beak shape so as to push the core  2  into the winding space without interfering with the winding roller B. 
     A rotating member  14  carrying a blade  15  protruding beyond the profile of the roller A is pivoted on the axis X of the first winding roller A. The member  15  has been called and will henceforth be called a blade, in that it causes severing of the web material, as will be explained below, but in fact it may not have, and preferably does not have, knife-type cutting edges. 
     The rotating member  14  is driven in rotation in the same direction as the roller A, which is anticlockwise in the appended figures, and is motorized separately by means of a belt drive  16  actuated by a motorized wheel  17  and passing round a tensioning roller  18 . Obviously, other actuating means can be provided for the rotating member  14 , such as, for example, chains, gears and the like. The wheel  17  can be controlled by a servo motor. 
     Operation of the machine according to two different embodiments, shown respectively in FIGS. 1A to  6 A and  1 B to  6 B, will now be illustrated, using in both cases the same reference numerals to designate like or similar parts. 
     In the embodiment according to FIGS. 1A to  6 A, the blade  15  has a concave shape toward the outside, substantially a very wide V shape, with the first leg, in the direction of rotation, longer than the other and less inclined with respect to the tangent to the winding roller A. 
     FIG. 1A illustrates the configuration of the machine during winding of the roll  1 , with the blade  15  in the resting position, that is with the rotating member  14  at a standstill. In this condition, the three rollers A, B, C all rotate at a constant and substantially the same speed, a speed which corresponds to the feeding speed of the web material. 
     In FIG. 2A the machine is near the changeover, that is about at the end of winding of roll  1 , when said roll is about to be discharged and a new core  2  must be inserted. In this stage the blade  15 , together with the rotating member  14 , is set in rotation by the motorized wheel  17  and the belt drive  16  in the same direction of rotation as roller A, indicated by the arrow F 1  in the appended figures. After an initial acceleration stage, the blade  15  reaches the same speed, or a very similar speed, as that of the web material W. 
     In the stage illustrated in FIG. 3A, the blade  15 , which travels at substantially the same speed as that of the web material W, has slightly raised the material W from the profile of the winding roller A and is accompanying it into the winding space. Again in this stage, the core inserting arm  10  begins to rise to bring a new core  2  into the gap between the two rollers A, B. 
     In FIG. 4A the log  1  is practically completed and severing of the web material is taking place. In this stage the pressure roller C has begun an acceleration stage, and the bottom roller B is possibly slowed, causing the roll  1  to move toward the outlet from the winding space. At the same time, or with slight staggering with respect to the acceleration of the pressure roller C, the blade  15  is slowed, so that the web material W has to slide on the contact edge  15 ′ of the blade  15 . In this situation, a transverse line of perforation of the web material comes to pass on the point of contact  15 ′ with the blade  15 , and tensioning of the web material due to acceleration of the pressure roller C causes such a lengthening as to cause separation of the material at said line of perforation, as shown in FIG.  5 A. 
     It can be advantageous for the blade  15  to have a high coefficient of friction, at least at the point of contact  15 ′ with the web material W, so as to facilitate severing of the web material. However, depending upon the types of material to be wound, the various types of perforations adopted, or even the lack of perforations on the web material, the blade  15  can assume different configurations, for example, with a continuous edge, serrated, or the like. 
     Returning to FIG. 5A, it can be noted that a new core  2 , on which an adhesive has previously been spread, comes into contact with the already separated web material W, beginning to wind it on itself, thus starting formation of a new roll  1 , which is moved into the winding space by a possible difference in speed between the rollers A and B, the latter having previously been decelerated. 
     This situation is shown in FIG. 6A, where the formed log has been expelled and a new log being formed is entering the winding space. The blade  15  is moving into the resting position and the core inserting arm  10  is going back to pick up a new core, to start a new winding cycle, and the three rollers A, B, C begin to rotate again at the same speed. 
     In the embodiment illustrated in FIGS. 1B to  6 B, the same series of stages is shown as in FIGS. 1A to  6 A of the first embodiment, therefore they will not be described in detail. 
     The substantial difference of this second embodiment with respect to the first lies in the fact that the blade  15  is accelerated instead of decelerated to cause separation of the web material W. For this purpose, the blade  15 , made of a material with a high coefficient of friction, is advantageously given a convex profile toward the outside. 
     In the situation in FIG. 4B, the acceleration of the blade  15  with the strong grip on the portion of web material W nipped by the new core  2  against the upper winding roller A, causes a further stretching of the web material and thus severing along the line of perforation between the core being inserted and the blade. 
     Of course the invention is not limited to the particular embodiments previously described and illustrated in the appended drawings, but numerous changes of detail within the reach of a person skilled in the art can be made thereto, without thereby departing from the scope of the invention, as defined by the appended claims.