PACKING PROCEDURE AND MACHINE FOR PUTTING INTO PRACTICE THEREOF

PROCEDE DE CONDITIONNEMENT ET MACHINE DESTINEE A LA MISE EN OEUVRE DE CE PROCEDE

English Abstract

While keeping the pallet (1) static, the method is essentially characterized
in that the reel (2) supplying the wrapping film is moved around said pallet
(1) in a rectangular trajectory (3) so that four segments of rectilinear
displacement are defined in every cycle of turn of the reel (2) for said reel,
which are related to one another by orthogonal inflections. The film pressure
is maintained constant throughout wrapping thereby preventing the film from
breaking. To this end, the reel (2) is mounted in a head (4) directly or
indirectly associated with the free end (8) of the multiple articulated arm
(7) of a robot (6) using a work program designed for the above-mentioned
movements so that the static nature of the pallet (1) during wrapping prevents
a the load from dropping off the pallet. The special movement of the reel (2)
around the pallet and its load prevents breaking of the plastic film. The
light weight of the head (4) and its accessories considerably limits inertia
in the machine.

French Abstract

Tout en maintenant la palette (1) statique, ce procédé consiste principalement à déplacer une bobine (2) de distribution de film de conditionnement dans un mouvement suivant une trajectoire (3) rectangulaire autour de la palette, de façon que lors de chaque cycle ou tour de la bobine (2), quatre tronçons de déplacement rectiligne soient définis en rapport les uns avec les autres par l'intermédiaire d'inflexions orthogonales, grâce à quoi la pression du film est maintenue constante durant tout le conditionnement, ce qui permet d'éviter les risques de rupture du film. A cette fin, la bobine (2) est montée sur une tête (4) reliée directement ou indirectement à l'extrémité libre (8) d'un bras à articulations multiples (7) d'un robot (6) possédant un programme de travail conçu pour effectuer les mouvements cités, de façon que le caractère statique de la palette (1) durant le conditionnement permet d'éviter la chute de la charge de la palette. Le mouvement spécial de la bobine (2) autour de la palette et de la charge permet d'éviter la rupture du film plastique et le poids réduit de la tête (4) avec ses accessoires permet de limiter considérablement l'inertie de la machine.

Claims

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CLAIMS
1.- Procedure for packing, which being specially
conceived to provide a pallet with its load with a
wrapping based on plastic foil or film which suitably
stabilises said load during subsequent handling of the
pallet during transportation thereof and being of the
type in which the pallet with its load is maintained
stationary during the packing, consisting in subjecting
the headstock (4) supporting the spool (2) of the film
to a cyclic motion of trajectory parallel to the outline
of the pallet (1), that is having a rectangular
trajectory, in which consequently are defined in each
cycle four segments of rectilinear displacement, related
to each other by orthogonal inflections, is
characterised in that the headstock (4) bearing the
support for the spool (2) of the film is supported and
manipulated by means of a robot (6) provided with a
multiple and articulated arm (7), extremity of the
headstock which can be submitted to a vertical movement
and another gyratory in order to adapt to the pallet,
all this such that the exit tension of the film (5) from
said headstock proves constant throughout the packing
and the tension also is constant with which said film is
adapted both to the faces and practically to the edges
of the pallet-load assembly, there being no lack of
uniformity of stretching and tension in the film which
could produce tearing therein.
2.- Machine for the putting into practice of the
procedure of the first claim, of the type of those which
incorporate a base on which the pallet stands, like for

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example a bed of rollers which permit the delivery and
removal thereof, base on which the pallet is maintained
stationary during the packing in order that a headstock
feeding plastic film (5) from a spool be displaced
around said pallet, characterised in that as means for
supporting and manipulating the aforementioned headstock
(4) a robot (6) is employed, with a program developed
for the movements of the packing operation, provided
with a multiple and articulated arm (7) to which said
headstock (4) is directly or indirectly attached.
3.- Machine, in accordance with claim 2,
characterised in that the articulated arm (7) of the
robot (6) is terminated in a vertical guide rail (9) for
the displacement of the spool-bearing headstock (4), in
such a manner that whilst the robot (6) provides said
headstock (4) with the annular motion around the pallet
(1), the vertical displacement of the headstock for the
helical wrapping of the film (5) is achieved by the
displacement of said headstock (4) on the aforementioned
guide rail (9).
4.- Machine, in accordance with claim 2,
characterised in that the articulated arm (7) of the
robot (6) provides the spool-bearing headstock (4) with
both the motion around the pallet (1) and its
displacement in the vertical direction.
5.- Machine, in accordance with claims 2 to 4,
characterised in that the spool-bearing headstock (4) is
provided with means for tilting (10) which permit it to
adopt an inclined disposition for the wrapping of the
"fifth face" or top base of the pallet (1) with its

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load.
6.- Machine, in accordance with claims 2 to 5,
characterised in that the headstock (4) supplier of the
film (5) incorporates, for the pre-stretching thereof,
between the pertinent spool (2) and the exit roller (11)
towards the pallet (1), a further two rollers (12)
motor-driven and substantially close to each other, with
distinct and adjustable speeds.

Description

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PACKING PROCEDURE AND MACHINE FOR PUTTING INTO
PRACTICE THEREOF
D E S C R I P T I O N
OBJECT OF THE INVENTION
The present invention relates to a new packing
procedure, with the clear objective of providing a
pallet with its load with a wrapping based on plastic
foil or film, which suitably stabilises said load during
subsequent handling of the pallet and/or protects it
from dust and water, procedure which has been specially
conceived in order to improve the packing conditions,
specifically by avoiding tears in the plastic film and
permitting a higher operational speed, with the
consequent enhancement in the performance of the packing
machine, with considerable stretching of the film and
consequent saving therein.
The new procedure permits the wrapping of four
or five faces indifferently, utilising a single spool of
film.
The invention concerns also the machine for
putting the procedure mentioned into practice.
BACKGROUND OF THE INVENTION
At the present time there are two basic
solutions for the packing of a pallet with its load,
both of which are based on winding over said assembly an

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adequately tightened plastic foil or film, in such a
manner that the pallet's load, generally made up of
separate elements, is perfectly bound in itself and to
the actual pallet, in order to ensure the stability of
the assembly in subsequent handling during transport.
One such solution consists in mounting the
pallet with its load on a rotating platform, whilst the
film-feeding spool is arranged laterally with respect to
the pallet and is subjected to a vertical displacement
movement, so that the plastic foil is wound helicoidally
over the outside surface of the load whilst the pallet
turns.
The fundamental problem with this solution lies
in that, in the initial phase of packing, that is when
the load is not secured, the centrifugal force produced
by the rotary movement of the pallet causes the same to
tend to be displaced in a radial direction and to fall,
which substantially limits the speed at which the pallet
is turned and consequently the working rate of the
machine.
Machines of this type are reflected, for
example, in the European Patents with application number
91401689.4 and 92401863.3.
The other solution consists in maintaining the
pallet stationary during packing, in order to avoid the
problems with centrifugal force of which mention was
made above, it being the film-feeding spool which
describes a planetary movement around the pallet, at the
same time as it simultaneously undergoes an alternating

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motion in the vertical direction, as for example occurs
in the machines reflected in the European Patent with
application number 90402027.8 or the PCT with
publication number WO 90/06261.
This second type of machine, structurally much
more complex than the first type, and consequently much
more expensive, and which due to its large turning
circle produces high inertial forces because of the
weight of the moving elements, which make necessary a
large reinforced framework. It also presents as a
fundamental problem, which is also applicable to the
case of the machines of the first type, a serious risk
of tearing the film as the pulling motion of said film
is in both cases circular and constant, meaning that
"tugging" occurs is said film in correspondence with the
folding the latter undergoes on reaching the corners or
upright edges of the load, in such a manner that in
correspondence with said edges extra straining and
stretching are produced which are the effects that
produce the risk of tearing which has just been
mentioned.
DESCRIPTION OF THE INVENTION
The packing procedure which the invention
proposes, applicable to a packing machine of the second
type of those mentioned above, that is of those in which
the pallet with its load is maintained steady during the
packing, resolves in a fully satisfactory manner the
aforementioned problems in the different aspects stated.
To this end and in more specific terms, the

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procedure of the invention consists in subjecting the
headstock of the film spool to a cyclic motion around
the pallet with its load, but with the special
particularity that said headstock describes a trajectory
always parallel to the outline of the pallet. More
specifically, in each cycle or turn of the spool around
the pallet, four segments of perfectly rectilinear
displacement are defined, parallel to the four faces of
the pallet, related to each other through orthogonal
inflections, in correspondence with the upright edges of
said pallet, that is, in contrast to the circumferential
trajectory of the headstock in the classic procedure,
with the procedure of the invention said headstock
describes a rectangular trajectory, all of this such
that the exit tension on the film from the
aforementioned headstock remains constant during the
entire packing and the tension is also constant with
which said film is applied both to the faces and to the
edges of the pallet-load assembly, there being no
uniform stretching and tensions in the film tending to
provoke tears therein.
Complementarily, both for achieving the putting
into practice of the procedure mentioned, and for
avoiding the problems of conventional packing machines,
inherent in the high inertia produced by the motion
thereof, the machine on which the object of the
invention is also centred, incorporates, in a lateral
disposition with respect to the zone of stationary
positioning of the pallet, a robot provided with an
articulated arm to which is directly or indirectly
joined the headstock carrying the film-feeding spool,
said robot coming with a program which permits it to

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describe the cyclic movement of rectangular trajectory
at constant speed of which mention has been made above.
The robot itself can also supply the spool-
s bearing headstock with the necessary movement of
vertical displacement, in order that the wrapping of the
film take place helicoidally, or this vertical movement
can be achieved by the coupling to the extremity of the
articulated arm of the robot of a vertical guide rail on
which the spool-bearing headstock in turn shall be
displaced. The employment of one system or another, or
the combination of both, depends on the maximum height
of the pallet to be wrapped.
Provision has also been made for the spool
bearing headstock to include a means of tilting which
permits it to adopt an inclined position, in the
uppermost location, for the wrapping of the top face of
the load formed on the pallet, that is for what is
commonly termed as wrapping of the "fifth face".
Finally and in accordance with another of the
characteristics of the invention, it has also been
foreseen that between the film-feeding spool and the
guide roller through which said film is channelled to
the pallet, two rollers are mounted for pre-stretching
the film, both motor-driven, in such a manner that the
stretching is produced by means of different velocities
in one and the other roller and over a very short
segment or path, it being moreover possible to graduate
or vary at will the desired degree of stretching by
means of the appropriate relative velocity between the
two rollers, adapting it specifically to the quality or

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characteristics of the film with which one is working.
DESCRIPTION OF THE DRAWINGS
To complete the description being made and for
the purpose of assisting in a better understanding of
the characteristics of the invention, in accordance with
a preferred practical embodiment thereof, attached
hereto as an integral part of said description, is a set
of drawings in which, by way of illustration and not
restrictively, the following is shown:
Figure 1.- Shows a schematic top plan
representation of a packing machine, in which, through
the presentation of various positions for the headstock
supplying the plastic film, the essential nature of the
procedure of the invention can be appreciated.
Figure 2.- Shows, according to a general
perspective, a specific practical embodiment of the
schematic machine of the previous figure.
PREFERRED E1~ODIMENT OF THE INVENTION
In the light of the foregoing figures, and more
specifically figure 1 it can be seen how, in accordance
with the procedure of the invention, the pallet (1),
with its load is maintained stationary, whilst the spool
(2) furnishing the film is the element which is
displaced around the pallet (1), but doing so with a
rectangular trajectory (3) according to the section of
the pallet (1), in such a manner that the headstock (4)
bearing the aforementioned spool (2) describes around

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the pallet (1) a trajectory in which four rectilinear
segments are described, parallel and close to the
respective faces of the pallet (1), related to each
other through orthogonal folds in correspondence with
the upright edges of the pallet (1), and more
specifically with the load positioned thereon.
In this manner it is achieved that the
instantaneous velocity of the spool (2) is constant over
the entire surface of the pallet (1), with the exception
of the very short spans corresponding to the inflections
of said trajectory in correspondence with the upright
edges of the pallet, whereby the tension in the plastic
film (5) is likewise constant and uniform, permitting a
higher working speed, without the risk of tearing the
film (5) in question.
This special mobility of the spool (2), and more
specifically of the headstock (4) upof~ which the spool
(2) is mounted, is achieved with the collaboration of a
robot (6) provided with a multiple and articulated arm
(7), to the free extremity (8) of which is fastened the
headstock (4), in such a manner that with the assistance
of a duly developed program for said robot (6), the
aforementioned movements of the headstock (4) are
achieved around the pallet (1).
The robot (6) can produce exclusively the
circumferential movement of the headstock (4) around the
pallet (1), following the rectangular trajectory of
which mention has been made previously, in such a manner
that said headstock (4) is not directly mounted on the
extremity of the multiple arm (7) of the robot, but

CA 02401584 2002-09-20
instead said headstock (4) is mounted on vertical guide
rails (9), as can be seen in figure 2, which are in
association with the extremity of the multiple arm (7)
of the robot, in a such a manner that the necessary
motion of the spool (2), for the helical wrapping of the
film (5) is produced by means of displacement of the
headstock (4) on the guide rails (9), whilst the latter,
driven by the robot (6), describe the rectangular
trajectory (3) or, as in the case of figure 1 the
headstock (4) can be directly fastened to the free
extremity (8) of the multiple arm (7) of the robot, in
which case said robot (6) must provide simultaneously
the headstock with both movements, the annular movement
(3) around the pallet (1) and the parallel and
complementary vertical displacement of said headstock
(4) .
In any case, provision has been made so that the
spool (2) may be mounted on the headstock (4) with
interposition of a gyratory disc (10) which permits the
spool (2) to take up a vertical disposition,
corresponding to the lateral wrapping of the pallet (1)
with its load, that shown in figure 1, or to adopt a
suitably inclined disposition, as shown in figure 2, for
the wrapping of the top base defined by the load of the
pallet (1).
In both cases provision is also made between the
spool (2) that feeds the film and the delivery roller
(11), that is the piece which suitably channels it
towards the pallet (1), for a pair of stretching drums
or rollers (12) to be fitted, both motor-driven,
substantially close to one another, as is shown in
figure 1 and having distinct and adjustable speeds, in

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order to permit, in turn, the degree of stretching in
the film to be regulated as a function of the
characteristics thereof. In this sense and for example
when the film is of poor quality, provided in origin
with some small hole, when the stretching takes place
said hole logically grows, it being possible that it
extend in an uncontrolled manner with the conventional
systems to the point where the film tears, whilst the
rollers (12) of the invention, by determining a very
short stretching space, do not grant sufficient time for
the "expansion" of said holes, thereby limiting
considerably the risk of tearing.

Representative Drawing