Patent Description:
The invention also relates to a method for stacking a fanfolded continuous web of sheet material of indefinite length, as defined in claim <NUM>.

Sheet materials, typically corrugated cardboard, have been long known to be used in box package production in the form of a web of sheet material that is folded into a fan-fold arrangement to reduce bulk and facilitate handling.

In fact, the raw sheet material is initially provided as a continuous web, like the continuous forms of old dot-matrix printers, i.e., consisting of a continuous sheet material of indefinite length composed of a succession of adjacent portions or sections of equal size, known as partitions, delimited by fold lines and alternately folded one on top of the other to form a stack of superimposed partitions.

The stacks of equal or different sizes are loaded into the magazines of an automatic or semi-automatic machine or plant for manufacturing boxes of desired sizes.

In order to obtain a stack, the continuous web initially undergoes a process of forming fold lines transverse to the longitudinal direction of the continuous web, normally by means of a creaser with at least two opposed pressing rollers for forming creases on the two sides of the continuous web that divide adjacent partitions, as described for example in <CIT> or <CIT>.

Once the fold lines or creases have been formed, the web undergoes a fanfolding step, i.e., alternate folding of adjacent partitions one on top of the other, followed by a step of stacking in a final unloading unit and cutting to a desired or standard height, as described for example in <CIT> or <CIT>.

Then, the fanfold stacks of sheet material are loaded into one or more storage magazines of a cutting and creasing machine from which the partitions are successively deployed and carried to feed the cutting and creasing units which will form single pieces (blankets) to be assembled into boxes.

<CIT> discloses an apparatus for folding and stacking a continuous web into flat partitions which has a feeding device for feeding a strip of sheet and a number of support elements which are guided along an annular guide for supporting the strip at the fold lines.

Furthermore, the support elements have an individual actuation control and can be displaced perpendicular to the direction of feed of the continuous web.

In particular, the continuous web has a horizontal orientation relative to the feeding device and is stacked horizontally on top of a conveyor belt which is adapted to temporarily support the stack of fanfolded sheet material and move it off the apparatus.

One drawback of this known system is that the fold lines are formed on one side only of the strip and the support elements always support the strip from the bottom. This may cause the formation of press creases in the strip also due to continuous changes of the feeding speed of the support elements.

Furthermore, the support elements project in cantilever fashion and laterally retract laterally to slide out of the fold lines and at this time the feeding speed decreases, thereby strongly affecting the working speed of the entire device.

One more drawback of this known system is that, once the continuous web has been folded, the conveyor belt supports the stack only along one side of the stack and along a single series of fold lines, which may cause the stack to be deformed under its own weight and further press creases to be formed.

<CIT> discloses a folding device equipped with a guided latch member for displacing a corrugated cardboard web at a fold. Further latch members are guided independently of the former latch member to carry along the corrugated cardboard web at another fold, which is arranged upstream of the former fold.

Also, a collection device is arranged downstream of a folding device for stacking the corrugated cardboard web, which is folded along the folds to form stacks.

One drawback of this known folding device is that once again the latch members operate on the cardboard web on one side only at one every two fold lines and cannot avoid the formation of press creases in the vicinity of the first latch member.

Furthermore, the feeding speed is limited by the complexity of the mechanism for moving the independent latch members elements, which are driven by annular belts or chains.

A further drawback is that each time the stack has to be cut in the collection device, the feeding speed of the continuous web decreases to allow the partition to be cut higher than the stack.

In the light of the prior art, the technical problem addressed by the present invention consists in allowing the continuous web to be cut to form stacks, while avoiding the formation of press creases and without slowing down or stopping the folding device.

The object of the present invention is to obviate the above discussed drawback, by providing a system and a method for stacking a fanfolded continuous web of sheet material of indefinite length, such as corrugated cardboard, that are highly efficient and cost-effective.

A particular object of the present invention is to provide a system as discussed above that can minimize the formation of press creases near the fold lines and avoid the need to slow down or stop the folding device.

Another object of the present invention is to provide a system as discussed above that can afford high-speed stacking of the continuous web without limitations in cutting the uppermost partition in the stack.

A further object of the present invention is to provide a system as discussed above that can be easily adapted to continuous webs of different widths.

Another object of the present invention is to provide a system as discussed above that can vertically align both sides of the stack.

These and other objects, as more clearly explained hereafter, are fulfilled by a system for stacking a fanfolded continuous web of sheet material of indefinite length, such as corrugated cardboard, as defined in claim <NUM>.

The system comprises a feeding device having means for guiding the continuous web in a longitudinal direction, a creasing device located downstream of the feeding device to form transverse creases on the continuous web spaced apart at a constant longitudinal pitch to define a succession of adjacent partitions, a folding device located downstream of the creasing device to progressively and alternately fanfold adjacent partitions along the creases.

A collection device is also provided for collecting the web folded into a stack of adjacent partitions, which comprises a vertically-extending column for retaining the stack of fanfolded adjacent partitions.

According to a peculiar aspect of the invention, a dynamic cutting unit is mounted at the top of the column, to act on the fly on the top adjacent partition of the stack while tracking stack-formation without stopping the folding device.

Due to this on-the-fly cutting operation of the cutting unit, the stack formation process may be tracked while the substantially horizontal plane on which the continuous web is laid above the stack remains unchanged, thereby avoiding the need to slow down or stop the folding device.

Advantageously, the column is equipped with a first stack-supporting rack and a second stack-supporting rack as well as a stack unloading unit mounted thereto on respective lifting carriages that are designed to move vertically along the column, and the cutting unit is mounted to a transverse end of the first supporting rack and is movable along substantially horizontal transverse guide means.

Furthermore, the cutting unit comprises a blade, a counter-blade and motorized drive means of belt and pulley type which are adapted to simultaneously move the cutting blade about its own axis and the transverse moving carriage of the cutting unit.

With this arrangement the uppermost adjacent partition of the stack may be acted upon to be cut while it moves vertically during stacking, thereby avoiding the formation of press creases and the need to slow down or stop the folding device.

The invention also relates to a method for stacking a fanfolded continuous web of sheet material of indefinite length, such as corrugated cardboard, as defined in claim <NUM>.

Advantageous embodiments of the invention are as defined in the dependent claims.

Further features and advantages of the invention will be more apparent from the detailed description of a system for stacking a fanfolded continuous web of sheet material of indefinite length, such as corrugated cardboard, which is described as a non-limiting example with the help of the annexed drawings, in which:.

Particularly referring to the figures, there is shown a system, generally designated by numeral <NUM>, for stacking a fanfolded continuous web M of sheet material of indefinite length, such as corrugated cardboard.

As is known per se, the continuous web M is substantially longitudinal, has a bottom side S<NUM>, a top side S<NUM>, longitudinal side edges B and comprises a predetermined maximum width E defined by the distance of the longitudinal side edges B.

As best shown in <FIG>, the system <NUM> comprises a frame defining a vertical center plane π and a feeding device, not shown, having means for guiding the continuous web M along a longitudinal direction L parallel to the vertical center plane π.

A creasing device <NUM> is also provided downstream of the feeding device and is adapted to form transverse creases C on the continuous web M spaced apart at a constant longitudinal pitch K to define a succession of adjacent partitions P.

The creasing device <NUM> may comprise two creasing rollers <NUM>', <NUM>" having tools configured to form creases C alternately on the bottom side S<NUM> and on the top side S<NUM> of the continuous web M for forming "Z" folds.

Therefore, at the output of the creasing device <NUM>, the web M will alternately and successively comprise a crease C<NUM> formed on the bottom side S<NUM>, for folding the web M upwards, and a crease C<NUM> formed on the top side S<NUM>, for folding the web M downwards.

Conveniently, the system <NUM> comprises a folding device <NUM> located downstream of the creasing device <NUM> for progressively and alternately fanfolding adjacent partitions P along the creases C.

As best shown in the figures, downstream of the folding device <NUM>, the system <NUM> comprises a collection device <NUM> for collecting the folded web M to stack adjacent partitions P.

The collection device <NUM> comprises a vertically-extending column <NUM> for retaining the stack of adjacent partitions P that have been fanfolded by the folding device <NUM>.

The column <NUM> comprises a plurality of uprights <NUM> anchored to the ground G and a plurality of cross members <NUM> which are adapted to stiffen the column <NUM> and create a compartment <NUM> for retaining the stack.

As best shown in <FIG>, a first stack-supporting rack <NUM>, a second stack-supporting rack <NUM> and a stack unloading unit <NUM> are mounted to the column <NUM>.

In particular, the first supporting rack <NUM> and the second supporting rack <NUM> comprise a plurality of arms <NUM>, which are transversely offset with a predetermined pitch, and the unloading unit <NUM> comprises a closed-loop conveyor belt <NUM> for temporarily supporting the stack and moving it transversely off the column <NUM>.

Furthermore, the first supporting rack <NUM> and the second supporting rack <NUM> are mounted to a first lifting carriage <NUM> and a second lifting carriage <NUM> respectively, which are vertically movable along the column <NUM>, and the lifting carriages <NUM>, <NUM> are mounted to a first transverse end <NUM>', <NUM>' of the first supporting rack <NUM> and the second supporting rack <NUM>.

Likewise, the unloading unit <NUM> is mounted to a third lifting carriage <NUM> which is vertically movable along the vertical column <NUM> to allow the unloading unit <NUM> to move down as the stack is being formed, with the substantially horizontal plane Q on which the continuous web M is laid above the stack remaining unchanged, as best shown in <FIG>.

Of course, appropriate vertical sliding means, not shown, are mounted along the vertical extent of the column <NUM>, for vertical and independent movement of the lifting carriages <NUM>, <NUM>, <NUM>.

According to a peculiar aspect of the invention, a dynamic cutting unit <NUM> is mounted at the top of the column <NUM>, to act on the fly on the top adjacent partition P of the stack while tracking stack-formation without stopping the folding device <NUM>.

Thus, a plurality of stacks may be obtained from the continuous web M without slowing down or stopping the creasing device <NUM> and/or the folding device <NUM>, as further described below.

As best shown in <FIG>, the dynamic cutting unit <NUM> is mounted to a second transverse end <NUM>" of the first supporting rack <NUM> facing the stack and comprises a fourth carriage <NUM> that is designed to move along substantially horizontal transverse guide means <NUM>.

The cutting unit <NUM> comprises a circular cutting blade <NUM> facing a counter-blade <NUM> for cutting the continuous web M, the blades being inclined to a predetermined angle to enable the adjacent top partition P of the stack to be intercepted to be cut.

Furthermore, motorized drive means <NUM> of the belt and pulley type are provided to simultaneously move the cutting blade <NUM> about its own axis and the fourth carriage <NUM> along the transverse guide means <NUM>.

As shown in <FIG>, in order to facilitate stack tracking, the first lifting carriage <NUM> and the second lifting carriage <NUM> comprise respective substantially longitudinal guide means <NUM> for selectively moving the first supporting rack <NUM> and second supporting rack <NUM> toward the stack to temporarily support it once the adjacent partition P has been cut.

Then, the continuous web M is cut on the fly immediately before the first carriage <NUM> and the second carriage <NUM> are moved toward the retaining compartment <NUM> to support the stack being formed.

As best shown in <FIG>, the stack that has just been cut is supported by the supporting racks <NUM>, <NUM> by tracking the formation of the stack while keeping the plane Ω on which the continuous web M is kept unchanged for the time required for the unloading unit <NUM> to unload the previous stack outside the column <NUM> and to climb up the corresponding vertical sliding means to collect the stack.

Then, the first supporting rack <NUM> and the second supporting rack <NUM> move away from the retaining compartment <NUM> along the longitudinal guide means <NUM> to unload the stack onto the unloading unit <NUM>.

In addition, to facilitate alignment of the creases C<NUM>, C<NUM> of each stack, the column <NUM> comprises first <NUM> and second substantially vertical leveling plates <NUM> for vertically aligning the creases C<NUM> of the top side S<NUM> and the creases C<NUM> of the bottom side S<NUM> respectively.

Preferably, before unloading the stack being formed on the unloading unit <NUM>, the first supporting rack <NUM> is removed from the stack while the second supporting rack <NUM> is pushed away toward the first supporting rack <NUM> and while the stack is being kept horizontally motionless by the leveling plates <NUM>, <NUM>, as shown in <FIG>.

In a further aspect, the invention relates to a method for stacking a fanfolded continuous web M of sheet material of indefinite length, such as corrugated cardboard, having a bottom side S<NUM>, a top side S<NUM> and longitudinal side edges B.

II will be appreciated from the above that the system for stacking a fanfolded continuous web of sheet material and the method of operation according to the invention fulfill the intended objects, and namely afford the formation of stacks without press creases and without slowing down or stopping the folding device.

The system and method of operation of the invention are susceptible to a number of changes and variants within the inventive concept as disclosed in the annexed claims.

While the system and method of operation have been described with particular reference to the accompanying figures, the numerals referred to in the disclosure and claims are only used for the sake of a better intelligibility of the invention and shall not be intended to limit the claimed scope in any manner.

Claim 1:
A system (<NUM>) for stacking a fanfolded continuous web (M) of sheet material of indefinite length, such as corrugated cardboard, which system (<NUM>) comprises:
- a feeding device having means for guiding the continuous web (M) in a longitudinal direction (L);
- a creasing device (<NUM>) located downstream of said feeding device to form transverse creases (C) on the continuous web (M) spaced apart at a constant longitudinal pitch (K) to define a succession of adjacent partitions (P);
- a folding device (<NUM>) located downstream of the creasing device (<NUM>) for progressively and alternately fanfolding adjacent partitions (P) along the creases (C);
- a collection device (<NUM>) for collecting the folded web (M) into a stack of adjacent partitions (P);
wherein said collection device (<NUM>) comprises a vertically-extending column (<NUM>) for retaining the stack of fanfolded adjacent partitions (P);
wherein a dynamic cutting unit (<NUM>) is mounted at the top of said column (<NUM>), to act on the fly on the top adjacent partition (P) of the stack while tracking stack-formation without stopping the folding device (<NUM>)
characterized in that a first stack-supporting rack (<NUM>), a second stack-supporting rack (<NUM>) and a stack unloading unit (<NUM>) are mounted to said column (<NUM>).