Machine for wrapping articles in stretchable film

The machine for the wrapping of articles in stretchable film of soft plastic material comprises a platform presenting a horizontal flat surface, onto which the article to be wrapped is positioned. The said platform is moved along a quadrangular path, effecting sequentially a lower horizontal run, during which it becomes loaded with the article, a upwardly directed vertical run, which brings the article in contact with the wrapping film and during which the proper wrapping cycle is started, a horizontal upper run, during which the wrapping operation is completed and the article is transferred away from the platform, and a downwardly directed vertical run, which brings again the platform to its loading position.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates to a machine for the wrapping of articles in 
stretchable film of soft plastic material. 
There are known, for example from U.S. Pat. No. 3,662,513 (FABBRI) and from 
U.S. Pat. No. 3,967,433 (BONFIGLIOLI), machines which carry out the 
wrapping of articles in stretchable foils of soft plastic material. Such 
machines of the prior art present however the inconvenience, whenever it 
is desired to wrap in a single package a plurality of loose articles, such 
as for example bottles or cans, that the said articles must be placed in 
suitable tray-like receptacles, since, during the wrapping operation, the 
whole item to be packaged is deposited on a vertically reciprocating 
lifting table the supporting surface of which is equipped with upwardly 
projecting supporting fingers or webs which are intended to be resiliently 
tipped over under the action of the folders which fold the edges of the 
film under the item. Obviously, the presence of the said upwardly directed 
resilient fingers or webs does not allow the stable positioning on the 
moving table of articles having a relatively small base such as bottles or 
cans. The problem of the stable positioning of this type of articles 
becomes precisely more evident in the case that it is desired to wrap in a 
single package a plurality of articles loosely arranged the one adjacent 
to the other. 
It is the main object of the present invention to provide a machine for 
wrapping articles in stretchable film, which can wrap in a single package 
a plurality of articles such as bottles, cans, small boxes or the like, 
loosely arranged in groups of predetermined number. 
It is a further object of the present invention to provide a machine for 
the wrapping of any articles in stretchable film, presenting remarkable 
operational speed characteristics, even higher than the operational speeds 
of the known machines. 
In the machine according to the invention, the item to be packaged is 
supported by a platform which presents a horizontal flat surface onto 
which the item to be wrapped (consisting of one or more articles) can be 
steadily positioned without the need of a support container or tray, and 
onto which surface the item can be slidably moved, during the completion 
of the wrapping operation without prejudice for its stability. 
The said platform is moved along a substantially quadrangular path, 
effecting sequentially a lower horizontal run, during which it is loaded 
with the article (or articles) to be wrapped, a upwardly directed vertical 
run, which brings the article in contact with the wrapping film and during 
which the proper wrapping cycle is started, a horizontal upper run, during 
which the wrapping operation is completed, and in the meantime the article 
being wrapped is gently transferred away from the platform, and a 
downwardly directed vertical run, which brings again the platform to its 
loading position. 
The closed-circuit continuous translatory movement of the platform along 
the mentioned quadrangular path consents therefore high operational 
speeds, which cannot be attained by the known type machines which employ 
vertically reciprocating platforms. 
The above and other objects and advantages of the wrapping machine 
according to the invention will appear evident from the following detailed 
description of a peferred embodiment of same, made, by way of non-limiting 
example, with reference to the attached drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
It is preliminarly to be noted that throughout the description and claims 
the term "article" or "articles" has been employed to designate the item 
to be wrapped. Particular attention (as already pointed out in the 
introductory part) is drawn to the fact that such "article" or "articles" 
may comprise a plurality of objects to be wrapped in a single package, 
such as may be bottles, cans, small boxes or the like, the said objects 
being loosely arranged the one next to the other in groups of a 
predetermined number. Of course the machine can handle as well single 
articles presenting a more regular shape, or loose articles arranged in 
tray-like containers, but it is pointed out that the representation in the 
attached drawings of a single article having substantially a 
parallelepipedal form, can by no means be considered as a limitation. 
With particular reference to FIG. 1, the machine for wrapping articles in 
stretchable film comprises a stationary frame F which houses the 
mechanisms for the operation of the machine itself. The article or 
articles P to be wrapped are fed to the lifting platform 1 of the machine 
through the feeding conveyor 16 and the movable loading platform 17, in 
the manner which will be described later. The lifting platform 1, loaded 
with the article (or articles) P moves vertically upwardly (dash-and-dot 
line A) to a position where the wrapping of the article is initiated, said 
wrapping being completed during an horizontal upper run (dash-and-dot line 
B) at the end of which the wrapped article P is discharged through a 
delivery conveyor 28, while the platform 1 performs a downwardly directed 
vertical run (dash-and-dot line C) and then a horizontal lower run 
(dash-and-dot line D) during which it receives a new article (or articles) 
P to be wrapped, thus getting ready for the repetition of another wrapping 
cycle. 
It can be therefore appreciated that, in order to preform a complete 
wrapping cycle, the platform 1, while maintaining a horizontal position of 
its supporting surface, is compelled to move along a quadrangular path Z, 
which is composed of the above mentioned substantially rectilinear runs A, 
B, C and D, which identify as many corresponding sides of an ideal square. 
Also, for the reasons which will appear more evident from the detailed 
description of the wrapping cycle which will be made after, and which can 
be briefly resumed in the requirement of avoiding brusque changes in the 
speed of the platform particularly in correspondence of the vertexes of 
the quadrangular path Z, which would cause an improper handling of the 
products carried by the platform or to be loaded on the platform itself, 
it is required that the platform 1 be moved along the quadrangular path at 
variable speeds, and more particularly that the speed of the platform 
progressively increase whenever same starts its movement from a vertex of 
a side of the square path Z towards the opposed side, reaching the maximum 
speed in correspondence of the middle of the side, and that the speed be 
progressively decreased as the platform gets near to the opposed vertex of 
the side. 
Referring particularly to FIGS. 11 and 12, there is illustrated a preferred 
embodiment of a motion imparting device suitable for moving the lifting 
platform 1 along the mentioned quadrangular path at the desired speed 
characteristics. Said device comprises a pair of parallel levers of equal 
length 2, 3 driven in synchronous rotation (arrow R) by respective driving 
shafts 4, 5 which shafts are arranged vertically the one above the other. 
The levers 2, 3 rotatably support at their free ends, about pins 6, 
respectively 7, the crank discs 8 and 9 which, in correspondence of 
excentrically arranged pins 10, respectively 11, support the vertical rod 
12 which carries at its upper end the lifting platform 1. The crank discs 
8, 9 are positively driven by respective gear trains, one of which (the 
one which drives crank disc 8) is illustrated in FIG. 12. More 
particularly, crank disc 8 is driven by bevel gear 13, which meshes with 
bevel gear 214 keyed at one end of shaft 14, presenting keyed at its other 
end bevel gear 114 meshing with bevel gear 15 which is fixed to the 
machine frame F. The rotation of driving shaft 4 in the direction of arrow 
R will consequently cause the rotation of crank pin 8 in the contrary 
direction. The gear transmission is dimensioned in such a manner that at 
each complete rotation of shaft 4 (and 5) there will be effected four 
rotations of crank pin 8 (and 9). By positioning the gear train as 
illustrated in FIG. 11, that is with the axis of shaft 4 and pins 6 and 10 
(and respectively the axis of shaft 5 and pins 7 and 11) in horizontal 
alignment, a complete rotation of associated shafts 4 and 5 will cause a 
translatory movement of platform 1 along the quadrangular path Z (composed 
of the four substantially rectilinear sides A, B, C and D) at the desired 
variable speeds. 
With reference to FIG. 1, the machine further comprises a storage roll 21 
from which a continuous web of stretchable film can be unrealed. The film 
web is guided over a first guide roller 22, and over a second guide roller 
24 carried by a vertically movable structure 26, so as to reach with its 
leading end the distributing clamp 25, also carried by the said structure 
26. On the vertically movable structure 26 there is also mounted a 
horizontal platform 27, consisting of a plurality of freely rotatable 
rollers. In the lower position of the vertically movable structure 26, the 
horizontal platform 27 is located at a level corresponding to the level of 
the upper horizontal run B of lifting platform 1. At this same level there 
is arranged the discharge conveyor 28. 
On the machine there are further arranged: a horizontally movable unreeling 
clamp 30 provided on its upper side with a cutting blade 34; a 
horizontally movable folding and supporting platform 31 consisting of a 
plurality of freely rotatable rollers, said platform being located at a 
level corresponding to the level of the upper horizontal run B of the 
lifting platform 1; a pair of opposed movable side clamps 33, and finally 
an upper movable thrusting member 32. 
OPERATION OF THE MACHINE 
One or more articles P, coming from the feeding conveyor 16, are loaded on 
the intermediate loading platform 17, which is located at the same level 
of the lower horizontal run D of the lifting platform 1 (see FIG. 1) and 
is horizontally movable to and fro with respect to a barrier element 19, 
fulcrumed on axis 20. When the platform 17 has been loaded with the 
desired number of articles, the feeding from conveyor 16 is stopped (for 
example through photosensitive means, not shown), and the barrier element 
19 is lowered so as to consent the horizontal displacement of the loaded 
platform 17 to a position beyond said barrier element 19 corresponding to 
the position of platform 1 whenever same reaches the vertex defined by 
sides D and A of the quadrangular path. At this moment, the barrier 
element 19 is again lifted, and the loading platform 17 is returned to its 
starting position, moving in synchronism with the lifting platform 1 which 
performs its horizontal lower run along side D. In this manner (see FIG. 
2) the article P is deposited on the lifting platform 1 which is ready to 
start its vertical upwardly directed lifting run A (see FIG. 1). 
In the meantime, the unreeling clamp 30 has moved towards the distributing 
clamp 25 and has gripped the leading edge of the film web thanks to its 
particular construction (see identations 125, FIGS. 9 and 10); then, it 
has moved horizontally away from the said distributing clamp 25, thus 
positioning a portion 121 of film above the lifting platform 1, having the 
article P positioned thereon. At this stage (see FIG. 9) the side clamps 
33 grip the transversal edges of the film portion 121 and stretch the said 
film portion in a direction which is transversal to the unreeling 
direction, as taught, for example, by U.S. Pat. No. 3,967,433. 
In the meantime (see FIGS. 3 and 10) the lifting platform 1 with the 
article P positioned thereon is lifted against the film portion 121 being 
held by its leading and trailing edges (referred to the direction of 
unreeling) respectively by the clamps 30 and 25, and by the side edges by 
the opposed clamps 33. If desired, the clamp 25 may allow some frictional 
slippage of the film, in order to avoid an excessive stretching of the 
film itself. Simultaneously, the structure 26 is lifted so as to 
constitute a barrier which blocks the article P against any side 
displacement in the direction of the upper horizontal run B of the lifting 
platform. 
The side clamps 33 are then moved toward each other under the lifting 
platform 1, so as to fold the transverse side edges of the film portion 
121 and effect the lateral wrapping of the article without any further 
stretching of the film. Thereafter (see FIG. 4) the folding and supporting 
platform 31 moves in the direction of the lifting platform 1, while this 
latter moves away along the upper horizontal side B of its quadrangular 
path. Simultaneously, the unreeling clamp 30 accompanies the movement of 
the said folding platform 31, while the side clamps 33 are opened so as to 
progressively release the side edges of the film in accordance with the 
movement of the said platform 31. In this manner, the platform 31 
progressively and smoothly takes the place of the lifting platform 1, 
while folding the leading edge of the film under the article P which 
cannot follow the side displacement of the platform since it is blocked by 
the barrier provided by the platform 27 in its elevated position. 
The synchronous and concurrent movement of folding platform 31 and of 
lifting platform 1 continues until platform 31 has completely substituted 
the said lifting platform 1 in supporting the article P, and the bottom 
folding of the leading edge of the film has also been completed since the 
clamp 30 has released said edge (FIG. 5). 
At this moment (FIG. 6) the structure 26 is lowered and the thrusting 
member 32 pushes the almost completely wrapped article along the platform 
27, so that the folding of the trailing edge of the film over the already 
folded leading edge is effected. In the meantime, the platform 1 has 
initiated its downwardly directed vertical run C. The clamp 30 (FIG. 7) 
continues its movement toward the clamp 25, and finally it severs with its 
cutting blade 34 the film portion from the continuous web. The clamp 30 
then reaches the distributing clamp 25 and grips a new leading edge of the 
continuous web of film, then it returns backwardly, unreeling a new film 
portion 121, while the completely wrapped articles is pushed onto the 
discharge conveyor 28 (FIG. 8). The machine is then set for a new wrapping 
cycle.