[0001] This invention relates to a method of packing a stack of goods with a shrink foil
which shrinks under the influence of heat, whereby the foil is fed from above in the
form of a tube from a supply to a shrink frame, the free end of the tube is secured
to the shrink frame and spead open, the tube is welded together transversely and cut
at a distance from the free end adjusted to the height of the stack to provide a sealed
length of the tube and to separate the sealed length of the tube from the supply respectively,
the sealed length of the tube being carried over the stack by the downwardly moving
shrink frame and whereby the heat shrinking takes place during the subsequent upward
movement of the shrink frame and an apparatus for performing the said method.
[0002] Such a method and an apparatus for the packing of goods has become known from the
DE-A-21 46 464. The known apparatus allows to rationalize the method to a very high
degree, thus enabling it to be carried out at one single station and without any significant
effort on the part of the operating personnel.
[0003] However, at high performances, there is the danger that the shrink foil which is
intended for the next following stack is shrunk by the upwardly-flowing heat too early.
Therefore, the output capacity of the known method and of the known apparatus is restricted
in practice. In order to overcome this disadvantage the method of this invention is
characterized in that during the heat shrinking the foil which is intended for the
next following stack of goods is shielded against the heat. One can thus in a simple
manner avoid that this foil is exposed to so much upwardly-flowing heat that it is
shrunk too early.
[0004] The apparatus of this invention for performing the above mentioned method comprises
a vertically movable shrink frame provided with spreading and gripping means, the
apparatus including the shrink frame being adapted to heat the foil surrounding a
stack, means for feeding a tubular foil from a supply down towards the shrink frame
from above, welding and cutting-off mechanism being mounted above the shrink frame
and is characterized in that there is provided a heat-shielding device between the
foil which is intended for the next following stack of goods and the shrink frame.
[0005] A further development of the apparatus is characterized in that the heat-shielding
device is provided by the welding mechanism which comprises a pair of welding jaws
which are arranged to close together during the shrinking. One can thus in a simple
manner accomplish a shielding-off of that foil which is not yet to be shrunk.
[0006] A further development of this embodiment is characterized in that the heat-shielding
device is provided by plates or screens which are placed above the welding mechanism,
thus making a feeding of the foil possible even during the shrinking process, so that
a new length of foil is already hanging ready when the shrinking process is concluded.
[0007] Further developments of this embodiment are defined in claims 5 and 6.
[0008] The invention will now be described in closer detail with reference to the accompanying
drawings which, to a high degree, are schematized, and where
fig. 1 is an embodiment of the apparatus according to the invention, seen obliquely
in perspective from the front,
fig. 2 shows this apparatus seen from the side,
fig. 3 shows this apparatus seen from the side,
fig 4 shows this apparatus seen from the side, but with the moveable parts in another
position,
fig. 5 is a cutting-off and welding mechanism for the apparatus, shown in schematic
form and partly in section,
fig. 6 seen from above and in schematic form, shows how the pre-spreading of the foil
is effected by means of movable suction boxes and a set of small grippers, and
fig. 7 shows a gripper of the type shown in fig. 6, in double right-angled configuration
and on a larger scale.
[0009] In fig. 1 there is shown an apparatus consisting of a horizontal shrink frame 1 which
is vertically movable on a column 2, said frame being designed to pack a box-shaped
stack 3 with shrink foil. The foil is in the form of a tube and comes from a supply
roll 4 at the back of the apparatus. The foil or tube is fed from here via rollers
or slide rails up over the apparatus and out into a console 5 which ends above the
shrink frame 1. The console 5 has built-in mechanisms forthe cutting-off and the wefding-together
of the tube. The console 5 also contains a pair or rollers for the feeding of the
foil. The inner edges of the shrink frame 1 are equipped with heating elements. With
the present invention it can be' expedient for these elements to be gas burners. Finally,
the apparatus has a control panel 6 with a programme control arrangement.
[0010] The spreading and the securing of the foil is automated, i.e., the apparatus is fully
automatic. for this purpose, the apparatus is equipped with a pair of suction boxes
7 and 8 mounted on the bottom of the shrink frame 1, and which on rails are controlled
for synchronous movement towards each other and away from each other. On the suction
boxes 7 and 8 are mounted elements which lie below the suction surfaces, but which
extend towards the corresponding element on the other suction box. However, these
elements are offset from each other in such a way that the suction surfaces of the
suction boxes can still lie almost or completely up against each other.
[0011] One or more suction blowers 9, 10 are mounted on each of the suction boxes 7 and
8, as shown in fig. 2 in association with the suction box 7. The suction side of these
blowers is naturally connected to the suction boxes, while the pressure side is connected
to the drawer-like elements 11 and 12 which extend under each suction box and can
be pushed in under this, or be in a half-drawn- out position in a direction towards
each other or in towards the middle of the shrink frame 1. This results in the provision
of upwardly-inclined nozzle slots. When the drawer-like elements 11 and 12 are in
the pushed-in position, which is the case when the suction boxes 7 and 8 are fed in
against each other, the discharge of air from the suction blowers is effected in another
manner. It should be noted that the drawer-like elements can also be mounted on the
suction boxes in a fixed way. As shown in fig. 6, on the suction boxes 7 and 8 there
is also mounted a first set of small grippers 13, 14, 15 and 16. For the sake of clarity,
these grippers are not shown in the foregoing drawings. These grippers have the double
right-angled configuration as shown in fig. 7. Fig. 6 also shows a tube 17 of shrink
foil which in its folded- together state has a double fold in each side, i.e., an
inwardly-bent edge and two outwardly-turning edges in each side.
[0012] As shown in figs. 1, 3 and 4, in conclusion the suction boxes 7 and 8 have a second
set of large grippers 18, 19, 20 and 21 in the form of pivotable stays capable of
swinging between a horizontal and a vertical position around horizontal axes. In fig.
3 the stays 19 and 20 are in the horizontal position, in that the stays run at right
angles to the plane of the paper.
[0013] Finally, above and in connection with the shrink frame 1 is mounted a second horizontal
frame 22 supported underneath by a column 23. The column 23 can have a built-in telescopic
part, thus enabling the distance of the frame 22 from the shrink frame 1 to be varied.
[0014] Fig. 5 shows a cutting-off and welding mechanism which is built into the outer end
of the console 5. A pair of rollers 24 and 25 feed the foil 26 to a slot between two
pairs of holding jaws 27, 28, 29 and 30, of which the last-mentioned and lower pair
also serve as welding jaws. A knife 31 is fastened to an endless chain 32, 33 and
is driven forwards and backwards by a not-shown motor in the suggested supports. The
knife can also be driven in the same direction the whole way around. The apparatus
functions in the following manner:
[0015] At the start of an operation, the shrink frame will be in its upper position, e.g.,
the position shown in the drawings. The feeding of the foil now takes place by means
of the pair of rollers 24 and 25 until the lower edge of the foil is level with the
lower edges of the suction boxes 7 and 8. Like the jaws 27, 28, and 29, 30, the suction
boxes 7 and 8 are, of course, moved into a position away from each other, so that
the foil can pass freely. The length of the foil hanging downwards is naturally adjusted
in accordance with the height of the stack to be packed. This length can be measured
off by means of the programme control arrangement, but it can also be effected automatically
with sensors already known within the art.
[0016] When the feeding of the foil is brought to an end, the suction boxes 7 and 8 are
fed in towards each other so that they surround the lower edge of the foil. The suction
blowers 9, 10 and others are then started, and the suction boxes 7 and 8 are withdrawn
a small distance away from each other and stopped. This position is shown in figs.
3 and 6. In this position, the small grippers 13, 14, 15 and 16 are activated and
swing in the direction of the arrows as shown in fig. 6, whereby they secure the four
outwardly extending edges of the foil cross section externally. The suction boxes
7 and 8 are then made to continue their movement until the foil cross section is opened
so much that the second set of grippers 18, 19, 20 and 21 can safely swing up inside
the foil. This happens at the same time that the first set of small grippers 13,14,
15and 16swing back into the start position as shown in fig. 6. It should be mentioned
here that the second set of grippers 18, 19, 20 and 21 are disposed a good distance
from the suction surfaces to ensure a correct upswing, and that this distance takes
on significance in the following step, during which the suction boxes move further
away from each other and thus through the grippers 18, 19, 20 and 21 tighten the lower
part of the foil cross section to form a rectangle. This results in the foil being
drawn free of the suction surfaces, thus allowing air to flow in. The effect is that
the suction blowers now come to supply air out of the upwardly-inclined nozzle slots
at the drawer-like elements 11 and 12, which are in the position as shown in fig.
3. A stream of air is thus blown up into the foil from two sides, and the foil can
now be released by the jaws 29 and 30 at the top, after the knife in the meantime
has been activated. The suction boxes 7 and 8 end in the position shown in fig 4,
where the frame 22 is of significance, in that the size of the frame 22 is of such
dimensions that it can prevent the upper part of the now formed foil hood from swinging
from side to side or flapping as a result of turbulence in the air. As mentioned,
the frame 22 can be adjustable in height if stacks of varying heights are being worked
with. Hereafter, the foil hood can be drawn down over the stack 3 without being damaged
by the upper corners or edges of the stack. This is carried out by feeding the frames
and the parts mounted thereon down the column 2. When the shrink frame has reached
its bottom position, the suction boxes are moved so much in towards each other that
the grippers 18, 19, 20 and 21 relieve the foil to such an extent that the grippers
can swing down into the horizontal position free of the foil, after which the shrinking
can begin during the upwards movement of the shrink frame. Prior to this, however,
the jaws 27, 28 and 29, 30 can have been moved towards each other into the closed
position, thus shielding-off the foil which must not be shrunk prematurely. In this
connection it can also be envisioned that regular heat-shielding plates or screens
can be mounted, thus allowing the foil to be fed while the shrinking is being carried
out, so that a length of foil is hanging ready under the jaws 27, 28 and 29, 30 when
the shrink frame has reached its upper position and is ready for a new operation,
whereby time can be saved. Consideration can also be given to cooling that space or
those spaces through which the foil is fed by means of a cooling fan.
[0017] Taken as a whole, it can be foreseen that especially the programme for the operation
of an apparatus according to the invention will be variable within a wide range. It
must thus be noted that it is not necessary to move the suction boxes towards each
other at the end of the process in orderto release the grippers 18,19,20 and 21 from
the foil. One can thus turn the grippers directly free of the foil to the horizontal
position.
1. Method of packing a stack (3) of goods with a shrink foil which shrinks under the
influence of heat, whereby the foil is fed from above in the form of a tube from a
supply (4) to a shrink frame, the free end of the tube is secured to the shrink frame
(1) and spead open, the tube is welded together transversely and cut at a distance
from the free end adjusted to the height of the stack (3) to provide a sealed length
of the tube and to separate the sealed length of the tube from the supply (4) respectively,
the sealed length of the tube being carried over the stack (3) by the downwardly moving
shrink frame and whereby the heat shrinking takes place during the subsequent upward
movement of the shrinkframe (1), characterized in that during the heat shrinking the
foil which is intended forthe next following stack of goods (3) is shielded against
the heat.
2. Apparatus for performing the method according to claim 1, comprising a vertically
movable shrink frame (1) provided with spreading and gripping means (13-16; 18-21),
the apparatus including the shrink frame being adapted to heat the foil surrounding
a stack (3), means for feeding a tubular foil from a supply (4) down towards the shrink
frame (1) from above, welding and cutting-off mechanism (29, 30, 31) being mounted
above the shrink frame, characterized in that there is provided a heat-shielding device
between the foil which is intended for the next following stack of goods and the shrink
frame (1).
3. Apparatus according to claim 2, characterized in that the heat-shielding device
is provided by the welding mechanism which comprises a pair of welding jaws (29, 30)
which are arranged to close together during the shrinking.
4. Apparatus according to claim 2, characterized in that the heat-shielding device
is provided by plates or screens which are placed above the welding mechanism (29,
30).
5. Apparatus according to claim 2, characterized in that the heat-shielding device
is provided by plates or screens which are placed below the welding mechanism (29,
30).
6. Apparatus according to one of the claims 3 to 5, characterized in that one or more
cooling fans are provided which are arranged to blow air in that space or those spaces
through which the foil is fed, especially inbetween the plates or the screens.
1. Verfahren zur Verpackung eines Stapels Güter (3) mit einer unter Hitzeeinwirkung
schrumfenden Schrumpffolie, wobei die Folie von einem Vorrat (4) dem Schrumpfrahmen
von oben in Form eines schlauches zugeführt wird, das freie Ende des Schlauches an
dem Schrumpfrahmen (1) befestigt und gespreizt wird, der Schlauch querverschweißt
und abgeschnitten wird in einem Abstand von dem freien Ende, der entsprechend der
Höhe des Stapels (3) eingestellt ist, um eine versiegelte Länge des Schlauches zu
gewährleisten und um die versiegelte Länge des Schlauches jeweils von dem Vorrat (4)
abzutrennen, wobei die versiegelte Länge des Schlauches durch eine Abwärtsbewegung
des Schrumpfrahmens über den Stapel (3) gebracht wird, und wobei die Heißschrumpfung
während der darauffolgenden Aufwärtsbewegung des Schrumpfrahmens (1) erfolgt, dadurch
gekennzeichnet, daß die für den nächstfolgenden Stapel Güter (3) vorgesehene Folie
während der Heißschrumpfung gegen die Hitze abgeschirmt wird.
2. Vorrichtung zur Durchführung des Verfahrens nach Anspruch 1, mit einem vertikal
beweglichen Schrumpfrahmen (1) mit Spreiz- und Greifeinrichtungen (13-16; 18-21),
wobei die den Schrumpfrahmen umfassende Vorrichtung so ausgestaltet ist, daß sie ein
einen Stapel (3) umgebende Folie erhitzt, mit einer Einrichtung für die Zufuhr einer
schlauchförmigen Folie von einem Vorrat (4) von oben nach unten in Richtung auf den
Schrumpfrahmen (1), einer Schweiß- und Abschneidevorrichtung (29, 30, 31), die oberhalb
des Schrumpfrahmens (1) angeordnet ist, dadurch gekennzeichnet, daß zwischen der für
den nächstfolgenden Stapel Güter vorgesehenen folie und dem Schjrumpfrahmen (1) eine
Hitzeschutzeinrichtung vorgesehen ist.
3. Vorrichtung nach Anspruch 2, dadurch gekennzeichnet, daß die Hitzeschutzeinrichtung
durch die Schweißvorrichtung gebildet wird, die ein Paar Schweißbacken (29, 30) aufweist,
die so angeordnet sind, daß sie sich während des Schrumpfvorganges schließen.
4. Vorrichtung nach Anspruch 2, dadurch gekennzeichnet, daß die Hitzeschutzeinrichtung
durch Platten oder Abschirmungen gehildet wird, die über der Schweißvorrichtung (29,
30) angeordnet sind.
5. Vorrichtung nach Anspruch - 2, dadurch gekennzeichnet, daß die Hitzeschutzeinrichtung
durch Platten oder Abschirmungen gebildet wird, die unter der Schweißvorrichtung (29,
30) angeordnet sind.
6. Vorrichtung nach einem der Ansprüche 3 bis 5, dadurch gekennzeichnet, daß ein oder
mehrere Kühlgebläse vorgesehen sind, die dergestalt angeordnet sind, daß sie Luft
in den Raum oder in die Raüme einblasen, durch die die Folie geführtwird, insbesondere
zwischen die Platten oder die Abschirmungen hinein.
1. Procédé d'emballage d'un empilement (3) d'articles au moyen d'une feuille rétrécissable
qui se rétrécit sous l'influence de la chaleur, la feuille étant amenée par le dessus
sous forme d'un tube à partir d'une réserve (4) et vers un cadre de rétrécissement,
l'extrémité libre du tube étant fixée au cadre de rétrécissement (1), déployée et
ouverte, le tube étant soudé transversalement sur lui-même et découpé à une distance
de l'extrémité libre qui est ajustée sur la hauteur de l'empilement (3) pour déterminer
une hauteur scellée de tube et pour séparer la longueur scellée de tube de la réserve
(4), respectivement, la longueur scellée du tube étant transportée au-dessus de l'empilement
(3) par le cadre de rétrécissement qui se déplace vers le bas et le rétrécissement
par la chaleur ayant lieu pendant le mouvement ascendant subséquent du cadre de rétrécissement
(1), caractérisé en ce que pendant le rétrécissement à la chaleur, la feuille qui
est prévue pour l'empilement d'articles (3) suivant est protégée de la chaleur.
2. Dispositif pour la mise en oeuvre du procédé selon la revendication 1, comprenant
un cadre de rétrécissement (1) mobile verticalement et muni de moyens d'écartement
et de saisie (13-16; 18-21), le dipossitif comprenant le cadre de rétrécissement étant
adapté à chauffer la feuille entourant un empilement (3), des moyens pour faire avancer
une feuille tubulaire à partir d'une réserve (4) vers le bas en direction du cadre
de rétrécissement qu'elle rencontre par la haut, un mécanisme de soudage et de découpe
(29, 30, 31) étant monté au-dessus du cadre de rétrécissement, caractérisé en ce qu'il
est prévu un dispositif de protection contre la chaleur entre la feuille destinée
à l'empilement d'articles suivant et le cadre de rétrécissement (1).
3. Dispositif selon la revendication 2, caractérisé en ce que le dispositif de protection
contre la chaleur est constitué par le mécanisme de soudage qui comprend une paire
de mâchoires de soudage (29, 30) montées de façon à se refermer pendant le rétrécissement.
4. Dispositif selon la revendication 2, caractérisé en ce que le dispositif de protection
contre la chaleur est constitué par des plaques ou des écrans qui sont placés au-dessus
du mécanisme de soudage (29, 30).
5. Dispositif selon la revendication 2, caractérisé en ce que le dispositif de protection
contre la chaleur est constitué par des plaques ou des écrans qui sont placés au-dessous
du mécanisme de soudage (29, 30).
6. Dispositif selon l'une quelconque des revendication 3 à 5, caractérisé en ce que
sont prévus un ou plusieurs ventilateurs de refroidissement qui sont aménagés pour
souffler de l'air dans le ou les espaces par lesquels la feuille est avancée, et notamment
entre les plaques ou les écrans.