This application claims priority to U.S. patent application Ser. No. 10/079,372, filed Feb. 19, 2002.
The present invention relates to a core feeding method in a rewinding machine for making logs of sheet or web material, for example used for the production of rolls of toilet paper, rolls of all purpose tissue paper for household use, non woven fabric, industrial rolls and the like.
Furthermore the invention relates to a rewinding machine that carries out this method.
Rewinding machines are known wherein a log is wound that is in contact surface with winding rollers. More precisely, the log is formed starting from a web of paper, continuous or with transversal perforations, which, carried by a first conveyor, is wound partially on an upper winding roller, enters into contact with a lower winding roller and is kept against the two upper and lower winding rollers by a pressure roller. The three rollers define a winding zone wherein the log is formed by feeding the web of paper and by dragging it for surface contact.
Normally, in the winding zone the log is formed on a tubular core. Once the log has reached a predetermined diameter, with a control normally on the paper length as wound, the web is cut or torn and the log is pushed away from the winding zone at the side opposite to the introduction zone of the core and, at the same time, a core is put in by a pusher.
Some rewinding machines, at the end of each winding step, provide a blade that cuts transversally the web against the upper winding roller, which has one or more cutting slots with which a retractable blade engages, mounted on an adjacent cutting roller.
In the case, instead, of rewinding machines with tearing system, the web is stopped upstream of or on the upper winding roller and the tearing is caused by the dragging action on the stopped web of the lower winding roller, on which the log is pushed by the pressure roller. Normally, a speed difference is created between said two rollers at the change of the log for causing the tearing.
Many methods exist for feeding the core into the winding zone. In a first case, a core at a time is fed on a loading tray and a pusher puts it into a winding zone. In this case, the pusher forces in a concentrated way against the core for forcing it between the winding rollers in presence of the paper, and it can get dented in the zone of contact, producing a faulty winding.
In a second case, the core is brought on a feeding cradle of curved shape located under the upper winding roller, whereby the friction against the upper roller brings it forward up to the contact with the lower winding roller for starting the winding. The cradle is formed by a series of curved guides that protrude rearwardly from the lower winding roller and are to it completely integral.
In presence of the feeding cradle, there is the advantage that a pad can be inserted between the core feeding point and the winding zone for tearing the paper. This way, the torn portion that is located upstream is caught automatically by the incoming core that is dragged by the upper roller against the cradle located underneath.
According to the size of the core, the lower roller is brought forward or away from the upper roller. However, a different cradle is necessary for each different diameter of the core. This causes stops in the production, an adjusting work and the need of a set of cradles, one for each different diameter of the core.
Other rewinding machines are known in the art, like those described in U.S. Pat. No. 5,769,352 or in U.S. Pat. No. 6,050,519.
In U.S. Pat. No. 5,769,352 a separate insertion device is provided to insert in the machine a core on which a web material is to be wound. The insertion device is arranged before a movable rolling surface and before a nip formed by an upper winding roller and a lower winding roller. The movable rolling surface forms, together with the upper winding roller a channel into which the core is inserted by the inserting device. A fixed portion of the rolling surface is provided integral to the support of the lower winding roller. The movable portion of the rolling surface rotates about a point of the inserting device. This causes a misalignments between the fixed portion and the movable portion.
In U.S. Pat. No. 6,050,519 the logs are wound with or without cores. This document provides a rolling surface between the upper and lower winding rollers that is integral to an arm that can rotate about the axis of lower winding roller. In the operation of the rewinding machine with cores, at the change of core diameter, the rolling surface must be changed. In fact, there is not a fixed portion of rolling surface that is integral to the axis of lower winding roller. The reason of moving the rolling surface is not related to changing the core size but to coreless winding.
It is an object of the present invention to provide a rewinding method for a web of paper for making logs, wherein the introduction of the core is carried out automatically on a cradle located beneath the upper winding roller, but wherein the change of the feeding cradle is not necessary according to the different diameter of the core.
It is another object of the present invention to provide a rewinding machine of a web of paper for making logs that is capable of carrying out this method.
It is a further object of the present invention to provide a rewinding machine in which the introduction of the core is carried out firmly for a variety of core diameters.
These and other objects are reached by the winding method of a web for making a log whose characteristic is that it comprises the steps of:
Its characteristic being that at least a portion of the cradle is movable with respect to a point integral to the support of the lower roller and is capable of lowering or rising towards/away from the upper winding roller.
Preferably, for each feeding step of a core, the movable portion of the cradle can be displaced from a first position of load of the core to a second position wherein the core contacts the upper roller.
Advantageously, for reaching the winding zone and remaining in contact with the upper roller, the core moves on the movable portion of the cradle and then on a fixed portion of the cradle that is integral to the lower roller. Furthermore for reaching the winding zone remaining in contact with the upper roller, the core is pushed by the cradle against the upper roller in a resilient way.
In its movement of lowering/rising the movable portion rotates about a point integral to the support of said lower roller.
In a first embodiment, said point is a pivot concentric to the lower roller.
In an alternative embodiment, said point is a pivot belonging to said fixed portion. Preferably, the core is put on the cradle when the movable portion is in lowered position, rolling on a downhill portion of the movable portion up to reaching a peeping stop element.
In particular, the steps can be provided of:
If the web is not cut or torn upstream, the contact of the core same against the upper winding roller causes the tearing of the web along a line of transversal perforation that is located between the core and the winding zone. In this case a step is provided of stretching the web between the core and the winding zone.
According to another embodiment, a rewinding machine of a web for making a wound log on a core, in particular for the production of rolls of toilet paper, rolls of all purpose tissue paper or non woven fabric for household use, industrial rolls and the like, comprises:
Its characteristic being furthermore that it comprises means for lowering/rising the cradle with respect to the lower roller towards/away from the upper roller.
Preferably, the cradle has a resilient surface for adapting to the passage of the core pushing it against the upper roller. In particular, the cradle has a curved surface with concavity oriented towards the upper roller.
Advantageously, the means for lowering/rising the cradle towards/away from the upper winding roller are operatively connected to an arm pivoted to the same support wherein the axle of the lower winding roller rotates.
Preferably, the cradle has a fixed portion integral to the lower roller located downstream of the movable portion, the movable portion cooperating with the fixed portion in order to form a single surface of support for the core during winding. Starting from the edge of the means for feeding the movable portion may have a portion downhill and a peeping stop element.
Means are provided for controlling the means for lowering/rising selectively the movable cradle to a predetermined height with respect to the upper winding roller.
Further characteristics and/or advantages of the rewinding method and of the rewinding apparatus according to the present invention will be made clearer with the following description of an embodiment thereof, exemplifying but not limitative, with reference to attached drawings wherein:
With reference to
Winding zone 4, according to the prior art, is formed by an upper winding roller 5, a lower winding roller 6 and a pressure roller 7. The latter follows the growth of the log 2a with the task of assuring its continuous contact with the winding rollers 5 and 6 and of controlling the growth of its diameter.
Between feeding roller 3 and upper winding roller 5 a counter support roller 8 is provided on which web 1 rests. Counter support roller 8 can be driven independently and comprises a cutting means 10 that engage with a cutting slit 9. Alternatively, the cutting roller can operate directly on upper roller 5.
At the end of each log, blade 10 engages with countersupport roller 8 (or with upper roller 5) for cutting web 1, thus creating a tail end 1a of the previous log 2a and a head end 1b of a log to be formed.
Log 2a, which has bee already wound, continues to be brought into rotation in zone 4 for tangential friction against upper winding roller 5, lower winding roller 6 and pressure roller 7.
The winding step had started by a core 20a, which had been put into zone 4 by a chain conveyor 22. Furthermore a core 20b is ready for acting as a winding support for a log to be wound, starting from the head end 1b of web 1.
According to the invention, upstream of zone 4 a cradle is provided (21,26) for feeding a core 20b. Cradle (21,26) is located beneath upper winding roller 5 and extends between the chain conveyor 22 of the core up to lower winding roller 6. Movable cradle portion 21 is movable and is capable of lowering or rising towards/away from upper winding roller 5. At the end of movable portion 21, core 20b is brought by a fixed cradle portion 26, to which the terminal portion 21a of movable cradle portion 21 is adjacent.
More precisely, in its movement of lowering/rising movable cradle portion 21 rotates integrally to an arm 23 that is pivoted concentrically to lower roller 6. A driven shaft 24 by means of a connecting rod 25 is capable of operating the movement of lowering/rising arm 23 and then movable cradle portion 21.
Always with reference to
Then, at the end of winding the previous log 2a, when the transversal perforation line 31 is located between core 20b and winding zone 4, with short and quick rising movement (
Peeping stop element 27 can be a harmonic steel blade, as that shown in the figure, or it can be a finger that is hinged to movable cradle portion 21 and yields by means of the action of a spring at the passage of the core (
According to the prior art, core 20b is preglued along at least a line, whereby it quickly catches end 1b at the passage from the positions of
Both movable cradle portion 21 and fixed cradle portion 26 have a curved surface with concavity oriented towards the upper roller. This surface, in a way not shown, may be resilient. For example it may have a surface coated of spongy material, or a plate suspended on springs, or a surface formed by a belt stretched between two ends.
As shown in
If the new core has not the same diameter as the previous one, it is necessary to adjust the machine for a new production campaign. More precisely, according to the different diameter of the core, lower roller 6, according to the prior art, is displaced in the direction of arrow, substantially in direction towards/away from the centre of lower roller 5. In this case, both fixed portion 26 and movable cradle portion 21, along with arm 23, follow integrally lower roller 6.
It is not, however, necessary to replace the cradle formed by cradle portions 21 and 26, since they have curved shape and movable cradle portion 21 is rotatable about support 28, in which the axle of lower roller 6 rotates, whereby when it presses onto core 20b (
As above said, the winding steps of web 1 for making a log 2a can provide the cut of the paper upstream of upper winding roller 5 (
Alternatively, the contact of core 20b against upper winding roller 5 can cause the tearing of the paper 1 along a transversal perforation line 31 of the paper that is located between core 20b and winding zone 4. In this case a step is provided of stretching the web between the core and the winding zone. This stretching can be carried out by accelerating the abandonment movement of already wound log 2a, for example, according to the prior art, with interposition between already wound log 2a and the lower roller of a fixed tray 32 (
The preferred embodiment of the invention of
With reference to
According to an embodiment of the invention, under upper winding roller 105 a cradle is provided (121, 126) for feeding a core 120. Cradle (121, 126) extends up to lower winding roller 106. A cradle portion 121 is movable and is capable of lowering or rising towards/away from upper winding roller 105. At the end of movable cradle portion 121, the core 120 is supported by a fixed cradle portion 126, to which movable cradle portion 121 is pivoted, at a point 133.
More precisely, in its movement of lowering/rising movable cradle portion 121 rotates integrally to an arm 123 about point 133. A driven shaft 124 by means of a crank 122 and a connecting rod 125 is capable of operating the movement of lowering/rising arm 123 and then of movable cradle portion 121.
Always with reference to
The operation is similar to that of
As shown in
It is not, however, necessary to replace the cradle formed by cradle portions 121 and 126, since they have curved shape and movable cradle portion 121 is rotatable about point 133 which is integral to support 129, where the axle of lower roller 106 rotates.
The position of a pivot at point 133 of fixed cradle portion 126 about which movable cradle portion 121 rotates is important to reduce vibrations of movable cradle portion 121 in certain conditions, with respect to the case shown in
The exemplary embodiment of
The foregoing description of specific embodiments will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt for various applications such an embodiment without further research and without parting from the invention, and it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiment. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.
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5639046 | Biagiotti | Jun 1997 | A |
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Number | Date | Country | |
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20060138272 A1 | Jun 2006 | US |