Unit for forming a layer of flat supports for a machine that produces packaging

A unit for forming one or more layers of individual flat supports, taken from at least a first conveyor device, conveying the supports from upstream to downstream at a first speed, that includes a second conveyor device, conveying the supports from upstream to downstream at a second speed lower than the first speed, positioned downstream of the first conveyor device, equipped with a receiving zone for receiving the supports arriving from the first conveyor device, and having a curved portion, and means for forming the layer positioned above the second conveyor device, situated downstream of the curved portion, and driven at the second speed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a 35 U.S.C. §§371 national phase conversion of PCT/EP2011/001653, filed Apr. 1, 2011, which claims priority of European Application No. 10004579.8, filed Apr. 30, 2010, the contents of which are incorporated herein by reference. The PCT International Application was published in the French language.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a unit intended to form one or more layers from individual flat supports or substrates. The invention also relates to a machine for producing packaging comprising such a unit for forming this or these layers.

2. Description of the Related Art

In a machine for producing packaging, an initial flat printing substrate, such as a continuous strip of cardboard, is successively unwound, printed and cut to a given shape. Each of the cutouts or boxes obtained is intended to form an item of packaging once it has been folded and glued. To make the packaging easier to assemble, the cutouts often have flaps extending from each of their sides and scoring to make the sides of the packaging easier to fold.

Once these cutouts have been produced, the initial substrate is then conveyed through a separation unit so as to position the various cutouts in several adjacent parallel lines. The separation unit causes the cutouts to deviate slightly from the initial longitudinal direction. It is possible afterwards to realign each of the cutouts in the same main direction using one or more alignment modules located downstream of the separator. This alignment module generally takes the form of two conveyor belts facing one another and one above the other. Each of the cutouts is inserted and moved at high speed between the two belts. The alignment modules, and therefore the cutouts, are distant from one another.

The next step is then to route each of these cutouts to the stacking station. However, the cutouts can be stacked and bundled correctly only if the cutouts are moving slowly. It is necessary to reduce the speed of the cutouts as they leave the alignment module. This slowing is generally achieved by transferring the cutouts onto a conveyor device situated downstream of the alignment module, the conveyor device moving at a lower speed by comparison with that of the conveyor device formed by the alignment module.

In order to reduce the length of the stacking and bundling unit and thus of the machine, it proves necessary to create a layer of cutouts. Thus, as many lines of layers are formed as there are cutouts across the width of the initial substrate. The cutouts are laid on one another with overlap as the flow of cutouts progresses. This arrangement and this progression of the cutouts in layer form also make it possible to maintain a constant rate of production.

The layer is formed by a transfer and by a speed differential between a first conveyor device, that conveys the cutouts quickly, and a second conveyor device that conveys the layer more slowly (see, for example, documents U.S. Pat. No. 3,942,786 and FR 2 784 085). The first conveyor device is either the alignment module or ramps of the separation unit.

Problems with recurrent jams have been noted in this transfer region. These jams are often caused by the difficulty in setting down a cutout that is moving at high speed and relatively freely on to a layer of cutouts that has already been formed and is moving more slowly. The speed differential between the rapidly-moving cutout and the slow-moving layer may notably result in incorrect orientation of the cutout once it has been set down on the layer. If this is not detected and corrected in time, this incorrect orientation may then in turn impede the setting-down of the next cutouts.

In many cases, one cutout becomes caught or even wedged in another, notably at their flaps, tabs, rim edges, cutouts, embossing or any other modifications. This wedging therefore causes jams which force the operator regularly to shut down the unit so that the normal flow of cutouts can be re-established.

This difficulty in correctly positioning the cutouts leaving the first conveyor device is also exacerbated by the way in which the cutouts behave while they are being transferred to the slow-moving second conveyor device. The second conveyor device is generally situated lower down than the exit from the first conveyor device, i.e. the alignment module. The cutouts are released from this exit before they reach the slow-moving conveyor device. As they fall, they are therefore subjected to the air currents generated by the conveyor devices or by the cutouts themselves. Their small thickness and relative lightness of weight therefore cause them to oscillate about an ideal path. It is therefore often difficult to control the path followed by the cutouts while they are being transferred at the instant that they arrive in the unit that forms them into a layer.

One first system for controlling the path of the cutouts is to insert a plurality of deflectors between the exit from the first conveyor device and the entrance to the second conveyor device. However, even though these deflectors appreciably reduce the risk of jams at relatively slow speeds, they prove to be insufficient when the cutouts are moving very quickly. In that case, the air currents generated within the machine have far too disturbing an influence on the path of the cutouts for the deflectors really to be able to confer an ideal path on the cutouts. Moreover, even at slow speeds, it is often necessary regularly and individually to readjust each of the deflectors in order to guarantee uniformity in the flow of the cutouts.

To supplement these deflectors, use is also made of press rollers positioned transversely to the slow-moving conveyor device in order to press firmly on the top of the lines of layers of cutouts. These press rollers are generally positioned just after the deflectors so as to press the cutouts leaving the first conveyor device firmly against the layer that is in the process of forming. These rollers therefore contribute to decelerating the cutouts from a high speed to a slow speed. However, these rollers prove to be incapable of limiting the risk of the cutouts becoming wedged in one another, notably at their respective flaps.

In the devices of the related art, the position of a substrate in the layer fluctuates further in the first few moments following its introduction to the layer because its speed has not yet become stabilized. It therefore has a tendency to slip on the substrate preceding it. This slippage further increases the risk of these substrates becoming wedged together and, therefore, of causing a jam in the unit.

SUMMARY OF THE INVENTION

A main objective of the present invention is to develop a unit for forming one or more layers of individual flat substrates. A second objective is to create a layering unit that allows effective control over the path of the cutouts. A third objective is to make the layering accurate by avoiding the cutouts becoming wedged in one another. A fourth objective is that of obtaining a layering unit that makes it possible to avoid the disadvantages of the related art. Yet another objective is that of providing a machine for producing packaging having a separation unit and a layering unit.

A unit for forming one or more layers of individual flat substrates, arriving from at least one first conveyor device, conveying the substrates from upstream to downstream at a first speed, comprises:a second conveyor device, conveying the substrates from upstream to downstream at a second speed lower than the first speed, positioned downstream of the first conveyor device, equipped with a receiving zone for the substrates arriving from the first conveyor device, and having a curved portion, andlayer-forming means, positioned above the second conveyor device, and driven at the second speed.

According to one aspect of the present invention, the unit is characterized in that the layer-forming means are situated downstream of the curved portion.

In other words, with the invention, the curved portion is used to curve an upstream individual flat substrate and position it on a preceding downstream individual flat substrate prior to the definitive layering. The unit is configured to curve the individual flat substrates after they have arrived one after another at the moment that they enter the curved portion and set them down on the substrates already set down on the second conveyor device. It is not until after this curving phase that the layer is formed by the means that form the layer.

On the one hand, this curving gives the substrate a bowed shape which is better suited to accepting the substrates that follow upstream arriving from the first conveyor device and which are set down at high speed on the second conveyor device. The substrates set down travel over the upwardly facing curved surface of the curved portion. The substrates that are set down on the substrates already set down are conveyed and guided more effectively than if they had been set down on a flat surface. Moreover, the curved shape also prevents flaps, tab, rim edges, cut lines, embossing or any other modifications of the substrate already set down from impeding the setting-down of the next substrates. These flaps, tabs, rim edges, cut lines, embossings or any other modifications must not interfere with the flaps, tabs, rim edges, cut lines, embossings or any other modifications of the next substrates and vice versa. With the invention, the risk of a substrate becoming wedged in one of these flaps, tabs, rim edges, cut lines, embossings or any other modifications has therefore become far lower, prior to layering.

Curving of the substrates also makes it easier for the substrates to be layered on the second conveyor device. Specifically, once the curved portion has been negotiated, the bowed substrate returns to the substrate preceding it in the layer that is forming. Its position in relation to this previous substrate does not change until the stacking step.

In another aspect of the invention, a machine for producing packaging is characterized in that it comprises the unit for forming one or more layers that has one or more of the technical features described hereinbelow and claimed, situated downstream of a unit for separating the flat substrates.

The upstream and downstream directions are defined with reference to the direction of travel of the substrates, in the longitudinal direction of the unit that forms the layer and through the packaging production machine as a whole. The longitudinal direction is defined with reference to the direction of travel of the substrates through the unit that forms the layer and through the machine, along the median longitudinal axis thereof. The transverse direction is defined as being the direction perpendicular to the direction of travel of the substrates.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In a machine (not depicted) for producing packaging, a continuous strip of cardboard is printed in a printing unit then cut in a cutting unit. As can be seen inFIG. 1, this cutting is done for example to form three initial lines or lanes C of identical individual flat cardboard substrates or cutouts10which are distributed uniformly across its width.

A separation unit1is arranged at the exit of the cutting unit (seeFIGS. 1 and 2). The separation unit1allows each of the cutouts arriving in the three initial lines C to be separated into three lines or lanes which are very distinct and transversely separated A. In this particular instance, the separation unit1thus consists of three separating conveying ramps2a,2band2cin a fantail configuration. Two of the lateral separating conveying ramps2aand2care arranged one on either side of the central separating conveying ramp2b. The fantail configuration allows the lines A of cutouts10to be separated transversely from one another.

Each of the separating conveying ramps2a,2band2ccomprises a motor-driven lower endless belt21and a motor-driven upper endless belt22. The cutouts10are held between the lower belt21and the upper belt22and are driven along by these two, lower21and upper22, belts.

During this separation phase, the cutouts10positioned in adjacent lines C are separated to give three continuous streams A of cutouts10. The cutouts10are also evenly spaced longitudinally from one another and travel at high speed within these streams.

At the exit from the separation unit1, the path of the cutouts10that have moved along the lateral separating conveying ramps2aand2cpositioned at an angle to the central separating ramp2bis realigned along longitudinal axes. To achieve this alignment, the machine for producing packaging comprises an alignment module which constitutes a first conveyor device3for subsequent layering. In this example in which there are three separating conveying ramps2a,2band2cfor the separation unit1, the first conveyor device3is equipped with an equivalent number of conveyor ramps, i.e. with three conveyor ramps3a,3band3c. The first conveyor device3is intended to accept each of the cutouts10arriving from the separating ramps and cause it to move and/or to pivot so as to orient and align it in a single longitudinal direction. Each of the conveyor ramps3a,3band3cis situated facing each of the separating conveying ramps2a,2band2c. In the case depicted inFIGS. 1 and 2, this direction corresponds more or less to the direction of the central conveying ramp2b. The three conveyor ramps3a,3band3care mutually parallel and parallel to the longitudinal axis of the machine.

Each of the conveyor ramps3a,3band3ccomprises a motor-driven lower endless conveyor belt31and a motor-driven upper endless conveyor belt32(seeFIGS. 1,3and4). The cutouts10are held between the lower belt31and the upper belt32and driven along by these two, lower31and upper32, belts. Each of the conveyor ramps3a,3band3ccauses the cutouts10to travel at a first given speed from upstream to downstream (arrow L inFIGS. 1 to 4).

The cutouts10leave the conveyor ramps3a,3band3cvia a distribution end33. The distribution end33is the downstream limit of the nip between the lower conveyor belt31and the upper conveyor belt32.

The machine comprises a unit that layers or that forms one or more layers with the cutouts10. The layering unit6is situated downstream of the first conveyor device3and therefore downstream of the separation unit1. The layering unit6is supplied with cutouts10by each of the conveyor ramps3a,3band3cof the first conveyor device3, the latter therefore being inserted between the separation unit1and the layering unit6.

The layering unit6could equally well operate without the presence of a first conveyor device3. In that case, the separating conveying ramps2a,2band2cof the separation unit1may act as first conveyor device moving along at the first given speed.

The layering unit6comprises a second conveyor device6aconveying the cutouts10from upstream to downstream. This second conveyor device6atakes the form of an endless conveyor belt, of which the upper surface supporting the cutouts advances from upstream to downstream (arrow S inFIGS. 1 to 4).

The second conveyor device6ais equipped with a receiving zone6bat the upper surface of the endless conveyor belt. Each of the cutouts10is set down on the second conveyor device6ain the receiving zone6b. The receiving zone6bfor example receives the front of the next cutout in the middle of the preceding cutout already set down.

This conveyor belt6amoves at a second speed that is lower in comparison with the first speed of each of the conveyor ramps3a,3band3cof the first conveyor device3. Each one of the distribution ends33of the conveyor ramps3a,3band3cis positioned upstream and above the conveyor belt6a.

Advantageously, a single deflector7is situated between the conveyor ramps3a,3band3cand the conveyor belt6a. This deflector7takes the form of an elongate plate. This plate7extends substantially across the entire width of the conveyor belt6a. This plate7is situated above the conveyor belt6a. This plate7is oriented obliquely in relation to the plane formed by the conveyor belt6a. The upstream upper edge of the plate7is positioned near the distribution end33of each of the conveyor ramps3a,3band3c. The downstream lower edge of the plate7is slightly raised in relation to the second conveyor belt6a.

The deflector7is configured to direct the cutouts10from the first conveyor device3toward the second conveyor device6. The deflector7allows almost identical paths to be impressed on the cutouts10leaving the distribution end33.

Having a single deflector7for all of the lines of layer makes it possible to avoid the problems of painstaking and repeated adjustments that operators have to perform. Of course, this single deflector7could if necessary be replaced by several deflectors distributed uniformly across the entire width of the conveyor belt6aand situated at the exit of each of the distribution ends33of the conveyor ramps3a,3band3c.

Three parallel layers10a,10band10care formed on the conveyor belt6aby the cutouts10leaving the conveyor ramps3a,3band3cone after another (seeFIG. 2) in three clearly distinct lines or lanes A. The layers10a,10band10care obtained as a result of the difference in speed between the conveyor belt6athat causes the layers10a,10band10cto progress slowly and the conveyor ramps3a,3band3cthat carry the cutouts10quickly.

The layering unit6comprises an intermediate roller8situated under the conveyor belt6alevel with its upper part. The intermediate roller8turns at a speed substantially equal to that of the conveyor belt6a.

The layering unit6comprises an upstream roller6cthat returns the end of the conveyor belt6a. The upstream roller6cis able to move up (arrows U inFIG. 3) or down (arrow D inFIG. 4), to move from a lowered position into a raised position and, conversely, from a raised position into a lowered position. When the upstream roller6cis in the lowered position (seeFIG. 3), the layering unit6is in a first configuration according to the invention. When the upstream roller6cis in the raised position (seeFIG. 4), the layering unit6is in a second configuration according to the invention.

In the first configuration (FIG. 3), the upper part of the conveyor belt6aprogresses from an upwardly inclined part situated upstream to a horizontal part situated downstream, because of the lowered position of the upstream roller6c. With the upstream roller6cin this position, the roller8forms at the surface of the conveyor belt6aa convex curved portion8asimilar to a bump or surface oriented and bulging upward. This portion8aforms an inflexion. This bump8aruns transversely across the entire width of the conveyor belt6a.

This bump8ais able to lift the cutouts10as they travel along the conveyor belt6aand to curve a downstream cutout, preparing it for the positioning of the upstream cutout that is to follow. The bump8ais situated downstream of the receiving zone6bon the second conveyor device6a. This position of the bump8aseparate from the receiving zone6bmeans that a cutout10can be received unimpeded on a cutout that has already been set down and curved. This makes it possible to prevent the cutout received at the receiving zone6bfrom interfering with the modifications, for example flaps, tabs, rim edges, cutting lines, embossings, of the cutout already set down.

In order to make it easier for the cutouts10to negotiate the bump8a, transfer devices in the form of rollers9aand9bare advantageously situated above the conveyor belt6aand a short distance therefrom. These transfer rollers9aand9bare rotationally driven, their rotational speed being lower than or substantially equal to the speed of travel of the first conveyor device3of the alignment module.

The first of these transfer devices, the upstream roller9a, is positioned between the deflector7and the intermediate roller8, i.e. between the bump8aand the first conveyor device3and above the second conveyor device6, so as to transfer the cutouts10, to accompany them along their path, and to slow them.

The second of these transfer devices, the downstream roller9b, is positioned above the second conveyor device6, substantially plumb with the bump8a, i.e. with the intermediate roller8, so as to transfer the cutouts10, accompany them along their path, and slow them.

During the formation of the layer10a,10b, and10c, these transfer rollers9aand9baccompany the cutouts10and direct them by impressing a path upon them before these cutouts10are definitively set down on the conveyor belt6a. This prevents the cutouts10from being subjected to significant torsional or stretching forces and thus avoids creasing or offset with respect to the main direction defined by the layer10a,10band10c. Because the transfer rollers9aand9bhave a circumferential speed that is not as high as the speed at which the cutouts10are progressing, they progressively slow the cutouts10just before the layer10a,10band10cis formed.

This first configuration with a bump8aand two transfer rollers9aand9bis more specifically intended for layering cutouts10of the “long grain” type or type that has an elongate shape and is arranged in the longitudinal direction.

In this first configuration, the longitudinal position of the upstream roller9ais set so that the distance between the distribution end33and the point on the conveyor belt6avertically in line with this upstream roller9acorresponds to the dimension of the cutout10, considered in the longitudinal direction. With this setting, a rear zone of the cutout10is released by the distribution end33only when a front zone of the cutout10comes into contact with the upstream roller9aand/or with the conveyor belt6a. The path of the cutout10thus remains constantly under control.

In the second configuration (FIG. 4), the upper part of the conveyor belt6aremains horizontal, because of the raised position of the upstream roller6c. The intermediate roller8remains positioned below the surface of the conveyor belt6a. With the upstream roller6cin this position, the conveyor belt6ahas no convex curved portion similar to bump or upwardly bulging surface8a.

To improve the layering10a,10band10c, the upstream transfer roller9ais positioned on the conveyor belt6aand upstream of the intermediate roller8. This upstream transfer roller9ais positioned just after the deflector7to press against the cutouts10newly set down on the conveyor belt6a. The rotational speed of the upstream transfer roller9ais equal to the speed of travel of the conveyor belt6a. The downstream roller9bis retracted upward.

This second configuration with no bump and with a single transfer roller9ais intended more specifically for layering cutouts10of the “short grain” type or the type that has an elongate shape and is arranged perpendicular to the longitudinal direction.

It should be noted that the position of the upstream roller9ais shifted upstream, the position of the conveyor belt6aremaining the same. This position makes it possible to reduce the distance between the distribution end33and the upstream transfer roller9awith respect to the distance provided in the first configuration. In this second configuration, the longitudinal position of the upstream roller9ais set so that the distance between the distribution end33and the point on the conveyor belt6avertically aligned with this upstream roller9acorresponds to the dimension of the cutout10, considered in the longitudinal direction. With this setting, an upstream lateral zone of the cutout10is released by the distribution end33only when a downstream lateral zone comes into contact with the upstream roller9aand/or with the conveyor belt6a. The path of the cutout10thus remains constantly under control.

In both the first and the second configuration, the layering unit6comprises means for forming the layer or layers10a,10band10c, in the form of a motorized feed device12. The motorized feed device12is positioned above the second conveyor device6a. The motorized feed device12is positioned downstream of the bump8a, in the region of the horizontal part situated downstream of the conveyor belt6a. The motorized feed device12comprises an endless conveyor belt situated above the conveyor belt6a. The motorized feed device12is driven at substantially the same speed as the second conveyor device6a.

The motorized feed device12is used to form and then stabilize the layers of cutouts10a,10band10c. Each of the lines of layers10a,10band10cis formed and compressed downstream of the bump8aand of the transfer roller or rollers9aand/or9bin a nip11between the conveyor belt6aand the motorized feed device12.

In the layering unit6, the receiving zone6bfor the cutouts10at the conveyor belt6a, the bump8aof the conveyor belt6aand the motorized feed device12are separate. This separation of functions, with arrival and receipt of the cutouts10, curving of the cutouts10and layering of the cutouts10means that the layering can be optimized. The cutouts10follow a path that is controlled and have a speed that is stabilized, thus avoiding the risks of jams.

The present invention is not restricted to the embodiments described and illustrated. Numerous modifications can be made without thereby departing from the context defined by the scope of the set of claims.