[0001] The present invention relates to a machine for forming a quadrangular bottom bag,
and to a method for forming the bag. EP-A-0 905 040 and DE-C-150 749 disclose conventional
quadrangular bags. US-A-2 837 983 discloses a quadrangular bottom bag forming machine
having a combination of features as set forth in the precharacterizing portion of
the appended claim 1
[0002] So-called "square-bottom" bags, i.e., bags whose bottom has and/or assumes the shape
of a regular quadrangle, are known and are used particularly but not exclusively for
packaging foodstuffs or chemicals such as for example sugar, flour-like products,
pasta, biscuits, frozen food, adhesives, cement and so forth.
[0003] Each bag of the known type is constituted by a substantially rectangular sheet, made
of paper or multi-ply material or plastics and is subjected to successive folding
and fixing steps.
[0004] In known bags, the bottom is constituted by flaps and/or tabs and/or wings that are
formed in the sheet by means of cutting operations, are mutually folded so as to overlap
and are then fixed by gluing or thermal bonding.
[0005] These square-bottom bags of the known type are not devoid of drawbacks, including
the fact that their formation requires the use of sheets that have a very large surface,
such as to allow to form the flaps (tabs and/or wings) which, once arranged mutually
adjacent, joined and folded so as to overlap, constitute the bottoms; this causes
an increase in the production costs of such bags and a considerable waste of material,
consequently worsening environmental conditions.
[0006] Other disadvantages of known square-bottom bags consist in that on their bottoms
there are lines and regions where the flaps (tabs and/or wings) are joined and connected.
[0007] Finally, known square-bottom bags are formed automatically by machines that have
a complicated constructive structure and a high cost due to the plurality of stations
and/or devices with which they are provided in order to perform the steps for forming,
folding and fixing the flaps (tabs and/or wings) that constitute the bottom of the
bags.
[0008] Furthermore, it is noted that these machines usually have a substantially fixed format;
format changing operations in fact entail a high cost and long execution times with
a disadvantageously extended halting of the production of the bags.
[0009] The aim of the present invention is to eliminate the above noted drawbacks of square-bottom
bags of the known type, by providing a method for forming a bag having a quadrangular
bottom and a machine for carrying out the method that allow to reduce the surface
of the sheets used to form the bags for an equal capacity with respect to known types
of bags, with a consequent containment of production costs, a reduction in material
waste and in environmental damage.
[0010] An object of the present invention is to ensure the strength of the bottoms of the
bags, preventing losses and leakages of the packaged products through them.
[0011] Other objects of the present invention are simplification of the constructive structure,
containment of production and installation costs for an equal operating speed, and
simplification of operations for changing the format of machines used for forming
the bags, further limiting production costs and times.
[0012] Within this aim, another object of the present invention is to provide a structure
that is relatively easy to provide in practice, safe in use and effective in operation.
[0013] In accordance with the invention, there is provided a machine for forming a quadrangular
bottom bag as defined in the appended claim 1, and a method for forming a square-bottomed
bag as defined in the appended claims method claims 2-4.
[0014] Further characteristics and advantages of the present invention will become better
apparent from the detailed description of a preferred but not exclusive embodiment
of a machine for forming a quadrangular bag, and of a method for forming bags, illustrated
only by way of non-limitative example in the accompanying drawings, wherein:
Figure 1 is a perspective view of a flexible sheet element for producing a bag having
a quadrangular bottom according to the invention;
Figure 2 is a perspective view of the element of Figure 1, provided with sealing means;
Figure 3 is a perspective view of the element of Figure 1, illustrating the fold lines
for forming the bag according to the invention;
Figure 4 is a perspective view of a bag made by the machine and method according to
the invention, with its bottom directed upward;
Figure 5 is a schematic front perspective view of the station for cutting and dispensing
the flexible elements of the machine for carrying out the method according to the
invention;
Figure 6 is a schematic front perspective view of the stations for locking the bottom
of the bag, folding the corresponding lateral flaps, and folding the main faces of
the machine according to the invention;
Figure 7 is a schematic front perspective view of the station for folding the lateral
flaps of the main faces of the machine according to the invention;
Figure 8 is a schematic front perspective view of a first position of the flap sealing
station of the machine according to the invention;
Figure 9 is a schematic front perspective view of a second position of the sealing
station of the machine according to the invention;
Figure 10 is a schematic front perspective view of the station for picking up the
bag formed by the machine according to the invention;
Figure 11 is a schematic front view of a machine according to the invention;
Figure 12 is a schematic side view of the machine of Figure 11;
Figure 13 is a schematic front view of another embodiment of the machine according
to the invention;
Figure 14 is a partially sectional enlarged-scale front view of a detail of the stations
for locking the bottom of the bag and for folding the corresponding lateral flaps
and main faces of the machine according to the invention, during locking;
Figure 15 is a view of the detail of Figure 14 at the beginning of the steps for folding
the flaps of the bottom and the main faces of the bag according to the invention;
Figure 16 is a view of the detail of Figure 14 at the end of the steps for folding
the flaps of the bottom and the main faces of the bag according to the invention;
Figure 17 is a schematic side view of the detail of Figure 14 at the end of the steps
for folding the flaps of the bottom and of the main faces of the bag according to
the invention;
Figure 18 is a schematic plan view of the station for folding the flaps of the front
faces of the machine according to the invention in the inactive configuration;
Figure 19 is a schematic plan view of the station of Figure 18 in a first active configuration;
Figure 20 is a schematic plan view of the station of Figure 18 in a second active
configuration;
Figure 21 is a schematic perspective view of the station of Figure 18.
[0015] With reference to the figures, the reference numeral 1 generally designates a bag
having a quadrangular bottom.
[0016] The bag 1 is constituted by a flexible sheet element 2 that has a substantially rectangular
elongated shape in which fold lines 3 form and articulate in a U-like shape a substantially
quadrangular central bottom 4 and two main faces, a front one 5 and a rear one 6,
that extend symmetrically from two mutually opposite sides of the bottom 4.
[0017] In Figures 1 and 2, the numeral 3a designates the imaginary outlines that correspond
to the lines 3 and have been shown merely for the sake of clarity and do not correspond
to outlines lines actually provided in advance on the sheet 2.
[0018] Indeed, it is noted that the bag 1 is formed starting from a sheet 2 on which no
plotting or definition of the outlines 3a is performed beforehand; the folding lines
3 are formed directly and instantaneously during the forming of the bag 1.
[0019] The bottom 4 and the main faces 5 and 6 are extended, at their mutually opposite
sides, by respective flaps 4a, 5a, and 6a, which can subsequently be folded and mutually
overlapped, so as to form the sides 7 of the bag 1.
[0020] There are also means for the lateral sealing of the bag 1, constituted for example
by regions 8 for the mutual fixing of the various overlapping flaps (4a, 5a and 6a);
the regions 8 are formed at least along the outer edges of some of the flaps.
[0021] For example, layers of adhesive 9 are distributed on the regions 8; as an alternative,
the regions 8 form regions for the bonding (thermal bonding, high-frequency bonding,
ultrasonic bonding, or the like) of the flaps.
[0022] The sheet 2 can be made of paper, multi-ply material, plastics or the like.
[0023] The method for forming the bag 1 consists in taking a flexible sheet element 2 having
a substantially rectangular elongated shape, in folding the sheet 2 substantially
in a U-like shape so as to form, with a mutual articulation, a front main face 5,
a central bottom 4 and a rear main face 6, in folding laterally to the main faces
5 and 6 the mutually opposite lateral flaps 4a of the bottom 4, giving said bottom
4 a quadrangular shape, and in then folding the mutually opposite lateral flaps 5a
and 6a of each one of the main faces 5 and 6, mutually overlapping them so as to constitute
the sides 7 of the bag 1.
[0024] The method according to the invention further consists in mutually sealing the flaps
4a, 5a and 6a that are overlapped so as to close the sides 7.
[0025] The sealing of the flaps consists in distributing on the fixing regions 8 a layer
of adhesive 9 that is suitable to fix the flaps once they have been overlapped or
in bonding the flaps, at the regions 8, with methods that are known in the field,
such as thermal bonding, high-frequency bonding, ultrasonic bonding, or the like.
[0026] The reference numeral 10 generally designates a machine for carrying out the method
according to the invention.
[0027] The machine 10 comprises a star 11 formed by a plurality of forming bodies (forms)
12 that duplicate the substantially parallelepipedal shape of the bag 1.
[0028] The star 11 can rotate stepwise about a substantially horizontal axis 11a that is
parallel to the main faces 5 and 6 of the bags being formed.
[0029] The star 11 lies below a station 13 for cutting and subsequently dispensing flexible
sheet elements 2 and moves the individual forming bodies 12 from a station 14 for
locking the bottom 4 and folding the corresponding flaps 4a in a matching direction
to a station 15 for forming and then folding the flaps 5a and 6a of the main faces
5 and 6.
[0030] The station 14 coincides with a station for folding in a matching direction the main
faces 5 and 6; in the station 14, the sheet 2 assumes the shape of a downward-facing
letter U.
[0031] The star 11 then conveys the forming bodies 12 toward a station 16 for sealing the
overlapping flaps and from there to a station 17 for picking up and overturning the
formed bag 1.
[0032] The overturned bag 1 is removed from the station 17 by way of conveyance lines, which
send it toward conventional filling and upper closure stations; said lines and stations
are not shown, since they are of a conventional type.
[0033] Filling can be performed by volume or by weight, while upper closure of the filled
bag 1 can occur, for example, by bonding or gluing the upper flaps of the bag 1.
[0034] The upper closure can be of the type with or without accordion-like portions and/or
with folding of the tips of the joined flaps along the sides 7 or on the upper face
of the bag 1.
[0035] As an alternative, upper closure of the bag 1 can occur by way of a double folding
of the accordion-like portion or with overlapping crossed tabs, or the like.
[0036] The cutting station 13 is constituted by a reel 18 of a continuous ribbon 19 of flexible
element that is unwound by rollers 20 and cut by blades 21 into sheets 2 whose length
is predetermined mechanically.
[0037] The cut sheets 2 are sent toward the star 11 by conveyance means of the type with
belts 22 or with grippers and are arranged above the forming body 12, which is motionless
in the station 14 for locking the bottom 4 and for folding the corresponding flaps
4a and the front and rear main faces 5 and 6.
[0038] Figures 11 and 12 illustrate a machine 10 in which the reel 18 is constituted by
a ribbon 19, which is equal in width to the larger dimension of the sheets 2 and is
arranged to the rear of the star 11 (wide-reel dispensing).
[0039] Figure 13 illustrates another embodiment of the machine 10, in which the reel 18
is constituted by a ribbon 19, which is equal in width to the smaller dimension of
the sheets 2 (narrow-reel dispensing) and is arranged laterally to the star 11. No
fold lines or outlines are impressed on the sheet 2; the lines 3 are in fact formed
during the formation of the bag 1 and are evident in the formed bag 1.
[0040] The locking station 14 comprises a pusher 23, which can move at right angles to the
bottom 24 of the forming body 12 that is motionless in the station and above which
a sheet 2 is arranged.
[0041] The pusher 23 supports, with the interposition of spring-loaded elastic means 25,
a pad 26 that can slide parallel to the direction of the motion of the pusher 23 and
rests on the bottom 24 of the forming body 12 in order to lock and fix thereon the
portion of the sheet 2 that corresponds to the bottom 4 of the bag 1 being formed.
[0042] Two fins 27 for folding the main faces 5 and 6 are articulated to the pusher 23 at
two first mutually opposite sides. The pusher 23 also has, at second mutually opposite
sides that are substantially perpendicular to the first sides, two lower wings 28
that are rigidly coupled thereto and are suitable to engage the mutually opposite
sides 29 of the forming body 12 in order to fold thereon the flaps 4a of the bottom
4.
[0043] The fins 27 are rotationally actuated by respective links 30, in which one end is
rigidly coupled to the corresponding fin 27 and the other end is associated with a
retention element that is not shown for the sake of simplicity of illustration.
[0044] The motion of the pusher 23 is such as to engage the wings 28 along the sides 29
of the forming body 12 so as to fold the flaps 4a of the bottom 4 and cause the rotation
of the fins 27 for the matching folding of the main faces 5 and 6 of the bag 1; in
this manner, the sheet 2 is given a substantially U-like shape and the bottom 4 is
given a substantially quadrangular shape.
[0045] The station 15 for forming and folding the flaps 5a and 6a comprises rear folding
units 31 that are arranged at the sides of the station and oscillate about respective
axes 31a and in mutually opposite directions in order to move from a position of noninterference
to a position in which they rest (sliding contact, tangential contact) against the
forming body 12.
[0046] The station 15 further comprises front folding units, which are constituted by two
plates 32 that are arranged substantially parallel to the sides 29 of the forming
body 12 and can move alternately from a configuration in which they are spaced from
the sides 29 of the forming body 12 to a configuration in which they are close thereto:
in this last configuration, the plates 32 are suitable to fold the flaps as the forming
body 12 passes between them.
[0047] During the step for folding the main faces 5 and 6 and the flaps 4a, the rear folding
units 31 and the plates 32 are fixed respectively in a noninterference and spaced
configuration (Figure 18) with respect to the forming body 12.
[0048] The folding of the flaps 5a and 6a to form the sides 7 of the bag 1 occurs by moving
the plates 32 toward each other and by rotationally actuating the star 11 and the
rear folding units 31 about their respective axes 11a and 31a.
[0049] The rear folding units 31 rotate at a higher peripheral speed than the star 11, so
as to fold onto the sides 29 of the forming body 12 the flaps 6a of the rear face
6 before the flaps 5a of the front face 5 are folded by contrast during the passage
of the forming body 12 between the plates 32 (Figures 19 and 20).
[0050] Once the flaps 5a and 6a have been folded so that they mutually overlap over the
flaps 4a, the forming body 12 is moved toward the sealing station 16, in which the
regions 8 for fixing the overlapping flaps are sealed by means of known methods that
depend on the material that constitutes the sheet 2 and on the kind of adhesive 9
applied, if any.
[0051] For example, if the sheet 2 is made of thermoplastic material, sealing can occur
due to the temperature and the station 16 is constituted by a heating section 16a
and a cooling section 16b; in the figures, the reference numeral 33 designates presser
elements that act on the regions 8.
[0052] Once sealing has occurred, the forming body 12 is moved into the pickup station 17,
in which the formed bag 1 is removed from the forming body 12 and overturned by grip
means 34 that move between a configuration for gripping and extracting the bag 1 and
a configuration for overturning said bag.
[0053] In practice it has been found that the described invention achieves the intended
aim and objects, and provides a bag having a quadrangular bottom which, for an equal
containment capacity with respect to known types of square-bottom bag, allows to reduce
the surface area of the sheets 2 that constitute said bags.
[0054] The average reduction of the surface area of the sheets 2 and therefore the saving
on the materials that constitute them is estimated to vary between 5% and 20%, and
this therefore achieves a reduction of bag production costs and environmental damage.
[0055] These reductions are due to the fact that the bottom 4 of the bag 1 is constituted
by a continuous portion of the sheet 2 formed by successive folding operations: the
bottom of the bag is no longer constituted by flaps and/or tabs and/or wings that
must be predefined by operations for cutting the sheet 2 and then overlapped and sealed.
[0056] Moreover, it is noted that the bottom 4 of the bag according to the invention, by
being constituted by a continuous portion of the sheet 2, has no folded, overlapped
and fixed regions and/or lines; accordingly, the bottom 4 is such as to avoid the
escape through it of the product packaged in the bag.
[0057] Finally, the machine for carrying out the method according to the invention is constructively
simpler and has lower production costs and higher operating flexibility than known
machines, since it does not have the stations for forming, cutting, folding and fixing
the flaps (tabs and/or wings) that constitute the bottoms of known types of bag because
the bottom of the bag is constituted by a continuous portion of the sheet 2.
[0058] The invention thus conceived is susceptible of numerous modifications and variations,
all of which are within the scope of the appended claims.
[0059] All the details may further be replaced with other technically equivalent ones.
[0060] In practice, the materials used, as well as the shapes and the dimensions, may be
any according to requirements without thereby abandoning the scope of the protection
of the appended claims.
[0061] Where technical features mentioned in any claim are followed by reference signs,
those reference signs have been included for the sole purpose of increasing the intelligibility
of the claims and accordingly, such reference signs do not have any limiting effect
on the interpretation of each element identified by way of example by such reference
signs.
1. A machine (10) for forming a quadrangular bottom bag, comprising multiple forming
bodies (12) that duplicate the shape of the bag (1) and move stepwise toward the main
faces (5,6) between a station (13) for cutting and then dispensing flexible sheet
elements (2), a station (14) for locking the bottom of the bag and for folding the
corresponding flaps (4a,5a,6a), a station for folding the front and rear main faces,
a station (15) for forming and subsequently folding the flaps of the main faces, a
flap sealing station (16) and a station (17) for removing the formed bag, said multiple
forming bodies (12) being disposed on a star (11) which is rotatable about an axis
(11a) that is parallel to the main faces (5,6) of the bags (1), said stations for
locking and folding the flaps of the bottom and main faces comprising a pusher (23)
that can move at right angles to the bottom (24) of the forming body and supports,
with elastic means (25) interposed, a pad (26) for resting against the bottom of the
forming body, characterized by two fins (27) for folding the main faces being articulated to said pusher at two
first mutually opposite sides, two lower wings (28) for folding the flaps of the bottom
of the bag being rigidly coupled to said pusher at second mutually opposite sides
(29) that are substantially perpendicular to the first sides, said fins being rotationally
actuated by respective links (30) in which one end is rigidly coupled to the corresponding
fin and the other end is associated with a fixed element, said station for forming
and folding the flaps of the main faces comprising rear folding units (31), which
are arranged at the sides of the station and oscillate in mutually opposite directions
between a noninterference position and a position for resting against the forming
body, and front folding units (32), which are suitable to fold the flaps during the
passage of the forming body.
2. A method for forming a square-bottom bag comprising the steps of: taking a substantially
rectangular flexible sheet element (3), folding said element in a substantially U-like
shape by means of two fins (27) articulated to two first mutually opposite sides of
a pusher (23) moving at right angles to a bottom (24) of a forming body (12) so as
to form, in a mutually articulated arrangement, a front main face (5), a central bottom
(4) and a rear main face (6), folding laterally to said faces the opposite lateral
flaps of said bottom by means of two lower wings (28) rigidly coupled to said pusher
at second mutually opposite sides (29), giving said bottom a substantially quadrangular
shape, then folding the opposite lateral flaps of each one of said front faces by
means of rear folding units (31) oscillating in mutually opposite directions between
a noninterference position and a position for resting against said forming body and
by means of front folding units (32) suitable to fold the flaps during the passage
of the forming body, said flaps being able to mutually overlap and being suitable
to form the sides of the bag, and mutually sealing said flaps.
3. The method according to claim 2, characterized in that said sealing step consists in distributing, on fixing regions (8) defined at least
along the edges of some of said flaps, a layer of adhesive (9) suitable to fix the
overlapping flaps.
4. The method according to claim 2, characterized in that said sealing step consists in bonding the overlapping flaps at fixing regions (8)
defined at least along the edges of some of said flaps.
1. Maschine (10) zum Formen eines Beutels mit viereckigem Boden, die mehrere Formgebungskörper
(12) umfasst, die die Form des Beutels (1) reproduzieren und sich schrittweise zu
den Hauptflächen (5, 6) zwischen einer Station (13) zum Schneiden und anschließendem
Verteilen von biegsamen Blattelementen (2), einer Station (14) zum Schließen des Bodens
des Beutels und zum Falten der entsprechenden Laschen (4a, 5a, 6a), einer Station
zum Falten der vorderen und hinteren Hauptfläche, einer Station (15) zum Formen und
anschließendem Falten der Laschen der Hauptflächen, einer Laschenversiegelungsstation
(16) und einer Station (17) zum Entfernen des geformten Beutels bewegen, wobei die
mehreren Formgebungskörper (12) auf einem Stern (11) angeordnet sind, der um eine
Achse (11a) rotierbar ist, die parallel zu den Hauptflächen (5, 6) der Beutel (1)
ist, wobei die Stationen zum Schließen und Falten der Laschen des Bodens und der Hauptflächen
einen Vordrücker (23) umfassen, der sich in rechten Winkeln zu dem Boden (24) des
Formgebungskörpers bewegen kann und mit zwischengeschaltetem elastischen Mittel (25)
eine Unterlage (26) zum Anlehnen an den Boden des Formgebungskörpers stützt, gekennzeichnet durch zwei Rippen (27) zum Falten der Hauptflächen, die an dem Vordrücker an zwei ersten
einander gegenüberliegenden Seiten gelenkig angebracht sind, wobei zwei niedrigere
Flügel (28) zum Falten der Laschen des Bodens des Beutels starr an den Vordrücker
an zweiten einander gegenüberliegenden Seiten (29) gekoppelt sind, die im Wesentlichen
senkrecht zu den ersten Seiten sind, wobei die Rippen durch entsprechende Gelenke (30) abwechselnd in Bewegung gesetzt werden, bei welchen ein
Ende starr an die entsprechende Rippe gekoppelt ist und das andere Ende mit einem
festen Element verbunden ist, wobei die Station zum Formen und Falten der Laschen
der Hauptflächen hintere Falteinheiten (31), die an den Seiten der Station angebracht
sind und in einander gegenüberliegenden Richtungen zwischen einer Nichteingriffsstellung
und einer Stellung zum Anlehnen an den Formgebungskörper pendeln, und vordere Falteinheiten
(32) umfasst, die geeignet sind, die Laschen während des Durchlaufs des Formgebungskörpers
zu falten.
2. Verfahren zum Formen eines Beutels mit viereckigem Boden, umfassend die Schritte des
Nehmens eines im Wesentlichen rechteckigen biegsamen Blattelements (3), des Faltens
des Elements in eine im Wesentlichen U-ähnliche Form mittels zweier Rippen (27), die
an zwei ersten einander gegenüberliegenden Seiten eines Vordrückers (23) gelenkig
angebracht sind, der sich in rechten Winkeln zu einem Boden (24) eines Formgebungskörpers
(12) bewegt, um in einer gegenseitig gelenkigen Anordnung eine vordere Hauptfläche
(5), einen mittleren Boden (4) und eine hintere Hauptfläche (6) zu formen, des seitlichen
Faltens der gegenüberliegenden seitlichen Laschen des Bodens an den Flächen mittels
zweier niedrigerer Flügel (28), die starr an den Vordrücker an zweiten einander gegenüberliegenden
Seiten (29) gekoppelt sind, was dem Boden eine im Wesentlichen viereckige Form gibt,
anschließend des Faltens der gegenüberliegenden seitlichen Laschen von jeder der Vorderflächen
mittels hinterer Falteinheiten (31), die in einander gegenüberliegenden Richtungen
zwischen einer Nichteingriffsstellung und einer Stellung zum Anlehnen an den Formgebungskörper
pendeln, und mittels vorderer Falteinheiten (32), die geeignet sind, die Laschen während
des Durchlaufs des Formgebungskörpers zu falten, wobei die Laschen fähig sind, einander
zu überlappen, und geeignet sind, die Seiten des Beutels zu formen und die Laschen
gegenseitig zu versiegeln.
3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, dass der Versiegelungsschritt im Verteilen einer Klebeschicht (9), die geeignet ist, die
überlappenden Laschen zu befestigen, auf Fixierbereichen (8) besteht, die wenigstens
entlang der Ränder einiger der Laschen definiert sind.
4. Verfahren nach Anspruch 2, dadurch gekennzeichnet, dass der Versiegelungsschritt im Kleben der überlappenden Laschen an Fixierbereichen (8)
besteht, die wenigstens entlang der Ränder einiger der Laschen definiert sind.
1. Machine (10) pour former un sachet à fond quadrangulaire, comprenant de multiples
corps de formage (12), qui reproduisent la forme du sachet (1) et se déplacent pas-à-pas
vers les faces principales (5, 6) entre un poste (13) pour découper, puis distribuer
des éléments en forme de feuilles flexibles (2), un poste (14) pour bloquer le fond
du sachet et pour plier les rabats correspondants (4a, 5a, 6a), un poste pour plier
les faces principales avant et arrière, un poste (15) pour former et plier ensuite
les rabats des faces principales, un poste (16) de scellement des rabats et un poste
(17) pour retirer le sachet formé, les multiples corps de formage (12) étant disposés
sur une étoile (11) qui peut tourner autour d'un axe (11a) qui est parallèle aux faces
principales (5, 6) des sachets (1), lesdits postes de blocage et de pliage des rabats
des faces inférieure et principale comprenant un poussoir (23), qui peut se déplacer
à angle droit en direction du fond (24) du corps de formage et supporte, moyennant
l'interposition de moyens élastiques (25), un tampon (26) destiné à s'appliquer contre
le fond du corps de formage, caractérisé par deux ailettes (27) servant à plier les faces principales et articulées sur ledit
poussoir sur deux côtés réciproquement opposés, deux ailes inférieures (28) pour plier
les rabats du fond du sachet et étant couplées rigidement audit poussoir sur des seconds
côtés réciproquement opposés (29), qui sont sensiblement perpendiculaires aux premiers
côtés, lesdites ailettes étant actionnées en rotation par des liaisons respectives
(30), dans lesquelles une extrémité est couplée rigidement à l'ailette correspondante,
et l'autre extrémité est associée à un élément fixe, ledit poste de formation et de
pliage des rabats des faces principales comprenant des unités de pliage arrière (31),
qui sont disposées sur les côtés du poste et oscillent dans des directions réciproquement
opposées entre une position de non interférence et une position d'appui contre le
corps de formage, et des unités de pliage avant (32), qui sont appropriées pour plier
les rabats pendant le passage du corps de formage.
2. Procédé pour former un sachet à fond carré, comprenant les étapes consistant à:
prendre un élément de feuille flexible sensiblement rectangulaire (3), plier ledit
élément selon une forme sensiblement en U au moyen de deux ailettes (27) articulées
sur deux premiers côtés réciproquement opposés d'un poussoir (23) se déplaçant à angle
droit par rapport à un fond (24) d'un corps de mise en forme (12) de manière à former,
selon une disposition réciproquement articulée, une face principale avant (5), un
fond central (4) et une face principale arrière (6), plier latéralement sur lesdites
faces les rabats latéraux opposés dudit fond au moyen de deux ailes inférieures (28)
couplées rigidement audit poussoir sur des seconds côtés réciproquement opposés (29),
donner audit fond une forme sensiblement quadrangulaire, puis plier les rabats latéraux
opposés de chacune desdites faces avant au moyen d'unités de pliage arrière (31) oscillant
dans des directions réciproquement opposées entre une position de non interférence
et une position d'appui contre ledit corps de formage, et au moyen d'unités de pliage
avant (32) convenant pour plier les rabats pendant le passage du corps de formage,
lesdits rabats étant à même de se chevaucher mutuellement et étant appropriés pour
former les côtés du sachet, et sceller mutuellement lesdits rabats.
3. Procédé selon la revendication 2, caractérisé en ce que ladite étape de scellement consiste à distribuer, sur des régions de fixation (8)
définies au moins le long des bords de certains desdits rabats, une couche d'adhésif
(9) convenant pour fixer les rabats en chevauchement.
4. Procédé selon la revendication 2, caractérisé en ce que ladite étape de scellement consiste à relier les rabats en chevauchement, dans des
régions de fixation (8), définies au moins le long des bords de certains desdits rabats.