FR2519951A1 - APPARATUS FOR STACKING FLAT ARTICLES AND CORRESPONDING STACKING METHOD - Google Patents

Abstract

Device for stacking flat articles arranged horizontally, the device comprising: a stop arrangement which is arranged horizontally and at right angles to the path of the articles rising up one above the other, a conveyor belt which is arranged in relation to the stop element in such a way that the articles fall flat onto the transport belt, a drive mechanism for the conveyor belt set in such a way that the articles falling onto the belt partially overlap one another, an arrangement for rapidly driving a group of articles on the conveyor belt and an arrangement for standing the articles upright when the group is further displaced by the rapid drive arrangement.

Description

FLAT ARTICLE STACKING APPARATUS AND STACKING METHOD
CORRESPONDING MENT.

 The present invention relates to the stacking of flat articles in a predetermined number, for example panty liners, period towels or baby diapers.

Flat articles of the type under consideration, such as panty liners, sanitary napkins and baby diapers, are relatively soft objects that are easily deformed. These articles are light and fragile and must undergo a minimum of manipulation so that the formed piles do not tend to deform when they are placed vertically.
These articles are of current consumption and are produced at very high rate by automatic machines of great flow whose cost is high. The stacking difficulties due to the nature of the articles themselves are therefore accentuated by the very high speeds at which the stacks must be formed. The different stacks are intended to be inserted in a package and therefore must all comprise the same number of articles; when the stacking operations are carried out as is known in the state of the art, the number of stacks whose packaging must be restarted is important.

 In addition to the aforementioned difficulties, these articles are fragile, that is to say that they cannot be inconsiderately compressed without losing some of their absorbent properties.

 There are already machines for stacking flat articles of the type under consideration, but these have many drawbacks. They are complex, not very robust and therefore have an unreliable operation in continuous operation. Given the high production lines of the production lines, they exert excessive efforts on flat articles. Certain types, reducing the forces applied to the articles, do not allow the production machines to be respected and require a slowdown of these.

 An important drawback of known machines is that changing the size of the articles or the number of articles in each stack requires significant modifications to the machines, and in particular complex disassembly.

 The invention relates to an apparatus for stacking flat articles of the type under consideration which is simple, robust and reliable in operation. The forces exerted on the articles are very low so that they are handled gently. The stacks are always formed with the same number of articles. The rates are very high and do not limit the speed of the production machines.

 Finally, changing the number of items per stack or the nature of the items requires only simple adjustments, without any disassembly or replacement of parts.

More specifically, the invention relates to an apparatus for stacking flat articles arranged horizontally and projected one by one in a first horizontal direction, comprising
- a stop device placed on the path of the articles projected horizontally, transversely to said path, so that the articles fall vertically flat under the action of their own weight
- A conveyor belt disposed in a second direction substantially transverse to the first and having a transport strand placed in a substantially horizontal plane, said belt being placed relative to the dis.

positive stop so that the articles fall flat on the substantially horizontal transport strand;
- a belt drive mechanism intended to advance it in such a way that, between the reception of two consecutive flat articles, the belt travels a determined distance less than the maximum dimension of the flat articles measured in the second direction so that consecutive items falling on the carpet partially overlap
a device for rapidly driving a group of articles deposited overlapped on the belt, by sliding on the transport strand in the second direction, and
- A device for straightening the articles of the group by stopping the previous article of the group by an inclined member while the group is still moved by the rapid drive device.

 It is advantageous that an article detector is placed at the entrance of the device. The belt drive device can then operate at a constant speed which depends on the rate of arrival of the flat articles and the desired overlap, a device interrupting the drive when the detector notes that an article is missing. In a variant, the belt drive device could advance by one or more steps after the detection of each flat article.

 The rapid drive device advantageously comprises at least one pallet, which is driven parallel to the transport strand, in the immediate vicinity thereof. It is then advantageous for the device to further comprise a second detector intended to record the passage of a pallet. A control member of the rapid drive device then advantageously causes the operation thereof, after the first detector has counted a predetermined number of articles, and the stop of operation, when the second detector indicates the passage of a pallet.

 The straightening device advantageously has its inclined stop member placed above a table which extends the transport strand. In a variant, the straightening device could have its inclined stop member placed above the conveyor strand of the carpet.

 According to an advantageous characteristic of the invention, the position of the stop member is adjustable as a function of the number and the thickness of articles of a group of tines to form a stack.

 I1 is advantageous that the inclined stop member and, if necessary, the pallets, have an inclination of 30 to 60 relative to a horizontal plane.

A device advantageously ensures the evacuation, in a direction parallel to the first direction, of a group of articles when that has been straightened,
The invention also relates to a method of stacking flat articles arranged horizontally and projected one by one in a first horizontal direction, comprising
- counting of projected items
- stopping each item successively so that it falls under the action of its own weight on a conveyor placed below it, in a second direction transverse to the first
- the displacement of the articles, which fell on the conveyor, so that an article falls while only partially covering the preceding article
- when the counting of the projected articles reaches a predetermined number, the rapid drive of the group of articles towards a stop member inclined from 30 to 600 relative to the horizontal plane and
- the recovery and evacuation of the group of articles, by sliding the previous article of the group along the stop member.

 Such a method advantageously further comprises compacting the group of articles by stopping the rapid drive when the rear article of the group reaches a predetermined location.

To better understand the object of the invention, there will now be described, by way of purely illusive and nonlimiting example, an embodiment shown in the accompanying drawing,
On this drawing
.- Figure 1 is a schematic plan view of a stacking device for flat articles according to the invention
- Figure 2 is a schematic side elevation along II-II of the apparatus of Figure 1;
- Figure 3 is an end view of the apparatus of Figure 1, shown with the adjacent end of a machine for producing flat articles, according to III-III of Figure 2.

 The machine shown diagrammatically in the various figures is intended to stack periodic towels in a determined number, ten in the example considered.

These articles are formed in a production machine, the outlet end of which is schematically represented in FIG. 3. The periodic towels 10 cut to size in a continuous strip pass between conveyor belts 12 towards a device 14 which cuts out rounded edges, before transmission to ejection rollers 16. The latter project the articles 10 at high speed in a substantially horizontal direction while they are flat in a horizontal plane. The layers then arrive in the stacking device according to the invention proper.

 The apparatus comprises a stop plate 18 placed along one side of a conveyor belt 20. As shown in FIG. 1, this stop plate 18 constitutes a lateral guide for the articles 10 projected successively. The upper strand of the belt 20, which receives the successive articles, is extended by a horizontal table 22 on which is mounted an inclined stop member 24. This is held by a rod 26 in an adjustment device 28 fixed to the table 22 and to the frame (not shown) of the device. The carpet 20 and the table 22 are aligned in one direction, which is perpendicular to the direction of arrival of the articles 10. Parallel to the direction of arrival of the articles 10, a chute 30 extends the table 22.On the other side from this table, opposite the chute 30, a jack 32 carries, at the end of the rod 34 of its piston, a plate 36 intended to drive out a stack of articles 10 formed on the table 22.

 Pallets 38 are intended to move along the surface of the upper strand of the belt 20, very close to the latter, and are carried by rods 40 which have extensions 42, which protrude from the rods 44 for supporting the rods 40 These chains 44 form a well known type of transporter.

 The drive of the device according to the invention is provided independently by a first assembly 46 which controls the carpet 20 and a second assembly 48 which controls the carnals 44.

 The apparatus further comprises a first detector 50, represented purely by way of illustration by a light source and an associated photoelectric detector, this detector being intended to note the passage of articles 10, which enter the apparatus. This comprises a second detector 52 which can be of any well-known type and which detects the passage of the extension 42 of a rod 40 for supporting a pallet 38 at a predetermined location.

 In the various figures, the items placed on the carpet have been identified by the reference 54 and, by the reference 56, the items in the position they occupy just before they are removed from the appliance.

 The apparatus operates in the following manner: the ejection rollers 16 of the production machine (FIG. 3) project the articles 10 at high speed, for example close to 100 mdmin, so that these articulations, due to their lightness and of their displacement by the edge, strike the stop plate 18. Given their flexibility, they do not rebound and fall flat on the conveyor strand of the mat 20. Although this has been shown with a width less than that of the articles, the arrangement can be reversed.

 The articles projected successively are distant from each other. For example, at the exit of the machine, they can be separated by a distance of between 3 and 30 cm. As the mat 20 advances, the articles fall on top of each other, only partially overlapping. It is important according to the invention that this overlap exists and is only partial. As shown in Figure 2, this partial recovery gives the articles good stability on the mat 20. Be detector 50 notes the passage of each article projected into the device. A logic circuit connected to the detector 50 counts the number of items projected and, when this number reaches a predetermined value, it controls the device 48 for driving the chains 44. This device 48 operates at high speed. As soon as it is triggered , it rapidly advances the 3S pallets so that the pallet closest to the articles 54 pushes the group of articles containing the predetermined number to the left in FIGS. 1 and 2 at high speed, that is to say that the pallet 33 has passed the drop location of the articles 10 when the next article falls on the carpet. The pallet quickly moves the group to table 22 and against the stop member 24. The previous article of the group strikes the bottom of the member 24. As the latter has an inclination of between 30 and 60 , and preferably of the order of 45, this previous article straightens and comes to rest against the member 24. It simultaneously pushes the following articles, which all take this inclination to twist 45. The pallet 38 also advantageously has an inclination corresponding to that of the stop member 24. As the group of articles must be packed but not excessively compressed, the pallet 38 is stopped as soon as the second detector 52 notes the presence of its extension 42. In this way, the group just packed but not compressed can then be driven by the plate 36 of the jack 32, towards the chute 30. This has sides whose inclination, near the table 22, corresponds to that of the member 24 and of the pallet 3; these sides gradually straighten in a helical fashion so that at the exit of the chute, the group forms a perfectly aligned stack, all the towels having their mean plane perpendicular to the bottom of the chute. The plate 36 is then returned to the rest position by the jack 32, and the apparatus is ready for a new operating cycle for the pallets 38. However, during this cycle, the production apparatus continued to project layers 10 if although the mat 20 already carries a number of layers 54, for example four or five.

 The operation described shows that the mat 20 must be sufficiently smooth so that it does not exert an excessive restraining force when the pallets 38 sweep the group of layers 54 towards the table 22. The latter and lor gane 24 must also be smooth so that they allow easy straightening of items.

 According to an advantageous characteristic of the invention, when the first detector 50 does not note the passage of articles for a certain time, the logic control circuit of the apparatus blocks the device 46 for driving the belt 20 so that the overlap layers successively deposited on the carpet is always the same. This result is obtained by means of a clutch-brake associated with the drive motor.

 The operation of the chain drive device 48 is triggered when the logic control circuit associated with the detector 50 indicates that the group carried by the belt contains the desired predetermined number of articles and is stopped when the second detector 52 indicates that the corresponding pallet is in the correct compacting position of the group formed.

 The foregoing description of the operation of the apparatus shows that it allows numerous adjustments and that these adjustments are independent. Thus, the criteria set by the production machine are the spacing of the articles and their speed of production, that is to say the time available between the fall of two successive articles.

This speed determines a minimum speed of movement of the pallets 38 so that they can drive a group without disturbing the fall of the next flat article. Experience shows that, when the articles are separated by a distance of the order of 50 mm, the chains must have a speed of between 0.5 and 1.5 m / s. This adjustment is simply carried out by adjusting the speed of training provided by the assembly 48, when the latter is ordered. The setting of the device, when the number of objects in a battery has to be changed, is very simple: the logic circuit is informed of the new number so that it triggers the 48 training session at the right time, and the stop member 24 is moved so that, when the pallet 38 comes to a stop, the group comprising the new number of articles is just packed.

 The rapid drive cycle of the group of articles and then of straightening and evacuation in the chute 30 requires a certain time before a new cycle can begin. The duration of this cycle sets a lower limit on the number of articles that a group can include. In the case of a production machine with 300 articles per minute and for the values indicated above, the minimum number of articles in a group is equal to five.

 The overlap of the flat articles 54 on the mat is adjusted independently using the drive device 46.

 Thus, the adaptation of the apparatus to different articles or to a different number of articles in each grouping is extremely simple and is carried out simply by adjustments independent of each other.

 The devices 46 and 48 for driving the belt 20 and the chains 44 respectively can be of very different types. For example, the device 46 may include a variable speed motor group, which is stopped in the event of a lack of articles. On the contrary, the device 48 may include a variable speed motor coupled by a clutch, which is only controlled when the logic control circuit indicates.

 In the apparatus described, the articles are straightened on a table 22 which extends the belt 20. This characteristic is however not essential, since the stop member 24 could be placed directly on the belt 20. In fact, the latter has a smooth surface so that the pallets 35 can easily entrain the layers on its surface; it therefore does not have too much of a disturbing effect on the group placed between the stop member and the pallet. This arrangement allows a shortening of the apparatus and in particular of the chains 44 which may have a reduced number of pallets.

 The apparatus described has many advantages.

First, it is simple and robust because it contains only a small number of elements already proven in the technique.

Its continuous operation is reliable. The handling of the articles is very gentle since they never undergo significant forces, except when the anterior end is impacted against the stop plate. The piles formed are always suitable because the partial recovery of the articles is adjusted according to their production rate.

 Thanks to its simplicity, the device can operate quickly and it does not require any restriction on the operating speed of the associated production line.

 The settings to be made when the number of articles per stack or when the nature of the articles are modified are simple and independent and do not require any disassembly.

 The apparatus and method according to the invention are particularly suitable for feminine and infant hygiene articles commonly produced from strips of fibrous or textile products and / or superimposed plastic sheets. Examples of such products are panty liners, sanitary napkins and baby diapers. However, the apparatus described could be suitable for many other articles, since it exerts only very reduced forces on the flat articles.

 It is understood that the apparatus described above may give rise to any desirable modifications without departing from the scope of the invention.

Claims (12)

REVEDDICATIONS  1 - Apparatus for stacking flat articles arranged horizontally and projected one by one in a first horizontal direction, characterized in that it comprises  - a stop device (lei) placed on the path of the articles (10) projected horizontally, transversely with respect to said path, so that the articles fall vertically flat under the action of their own weight;  - a conveyor belt (20) disposed in a second direction substantially transverse to the first and having a transport strand placed in a substantially horizontal plane, said belt being placed relative to the stop device (18) so that the articles fall flat on the substantially horizontal transport strand;  - a mechanism (46) for driving the belt (20) intended to advance the latter, so that, between the reception of two consecutive flat articles, the belt (20) travels a determined distance, less than the maximum dimension flat articles measured parallel to the second direction, so that the consecutive articles falling on the belt (20) partially overlap  - A device (38, 48) for rapid group drive. articles deposited with overlap on the belt (20), by sliding on the transport strand in the second direction, and  - A device for straightening the articles of the group by stopping the anterior article of the group by an inclined member (24) while the group is still moved by the rapid drive device.  2 - Apparatus according to claim 1, characterized in that it comprises a first detector (50) of flat articles projected in the first direction.  3 - Apparatus according to claim 2, characterized in that the device (46) for driving the belt (20) drives the latter at a constant speed, which is a function of the rate of arrival of the flat articles, and comprises a drive blocking device, when the first detector (50) notes a lack of article.  4 - Apparatus according to one of claims 1 to 3, characterized in that the rapid drive device comprises at least one pallet (38) driven parallel to the transport strand, in the immediate vicinity thereof.  5 - Apparatus according to claim 4, characterized in that it comprises a second detector (52), which identifies the passage of a pallet (38).  6 - Apparatus according to claim 5 characterized in that it comprises a control member of the rapid drive device so that it operates after the first detector (50) has counted a predetermined number of articles and ceases to operate when the second detector (52) indicates the passage of a pallet (38).  7 - Apparatus according to one of claims 1 to 6, characterized in that the straightening device comprises an inclined stop member (24) disposed on a table (22) which extends the conveyor strand of the carpet (20) .  8 - Apparatus according to one of claims 1 to 7, characterized in that the position of the inclined stop member (24) is adjustable, in particular depending on the number and thickness of the articles of a group .  9 - Apparatus according to one of claims 1 to 8, characterized in that the inclined stop member (24) and the pallets (38) have an inclination relative to a horizontal plane between 30 and 600.  10 - Apparatus according to one of claims 1 to 9, characterized in that it comprises a device (30, 32, 36) ensuring the evacuation of a group of articles stacked in a direction parallel to the first direction .  11 - Apparatus according to claim 10, characterized in that the discharge device comprises a pusher member (32, 36) moving in the first direction to ensure the transport of a group of stacked articles and its introduction into a straightening chute (30).  12 - Method for stacking flat articles arranged horizontally and projected one by one in a first horizontal direction, characterized in that it comprises:  - counting of projected items (10)  - Stopping each item successively so that it falls under the action of its own weight on a conveyor (20) placed below it in a second transverse direction relative to the first  - moving the articles, which have fallen on the conveyor (20), so that an article falls while only partially covering the previous article  when the counting of the projected articles (10) reaches a predetermined number, the rapid driving of the group of articles in the second direction towards a stop member (24) inclined from 30 to 600 relative to a horizontal plane, and  - Straightening and evacuating the group of articles by sliding the previous article of the group along the stop member (24).