Method of and apparatus for wrapping an article

A method for setting pieces of wrapping material, in a machine for wrapping articles with pieces of wrapping material, during the wrapping phase of the article, includes transporting each single wrapping material piece by means of a plurality of bar means which are disposed set apart with reference to the transport direction, and cooperating with each other. An apparatus for carrying out this method includes a plurality of closed loop transport means, at least one wrapping bar associated to each one of the above mentioned transport means, driving means designed to drive, in proper connection, the transport means.

FIELD OF THE INVENTION 
The present invention relates to a method of and an apparatus for 
transporting a piece of wrapping material during the article wrapping 
phase in a machine for wrapping articles with pieces of wrapping material, 
particularly heat-shrinkable material. 
BACKGROUND OF THE INVENTION 
A wrapping machine as described in U.S. Pat. Nos. 3,791,100, 5,203,144 and 
5,203,146, generally comprises: 
a first conveyor, supporting the articles to be wrapped and feeding them 
one by one to a second conveyor; 
a second wrapping phase conveyor having an inlet end, an outlet end, and an 
upper surface between the inlet and outlet ends, this upper surface 
supporting and conveying articles while they are wrapped in succession; 
means for feeding single pieces of wrapping material, in succession, to the 
wrapping phase conveyor, placing the leading extremity of each piece on 
the upper surface of the wrapping phase conveyor, at the inlet end 
thereof; 
wrapping means comprising an endless conveyor carrying at least one 
wrapping bar along a path surrounding the above mentioned wrapping phase 
conveyor, and carrying the heat-shrinkable set the above mentioned 
heat-shrinkable wrapping pieces over and in front of each article then 
placing the rear extremity of the piece in a region between the second 
conveyor and the upstream end of a third receiving conveyor; 
a third receiving conveyor, for receiving and supporting the partially 
wrapped articles, aimed placing the rear extremity of the wrapping 
material piece under the leading extremity of the same wrapping material 
piece; and 
synchronising means, designed to set in proper timed relation the first 
conveyor, the first conveyor, the motion of the above mentioned second 
conveyor, the means for feeding the wrapping material, the endless 
transport means and the related wrapping bar, and the motion of the third 
receiving conveyor. 
These machines, made as explained hitherto, are affected by several 
drawbacks as far as the transport of the wrapping material piece by the 
wrapping bar endless transport means is concerned.

DESCRIPTION OF PRIOR ART 
With reference to FIGS. 1, 2, 3, 3a and 3b, which show a sequence of 
operations in the main wrapping stages, in which an article is wrapped 
while being made to advance, in accordance with the known method as 
described above, the article is fed by the feeding conveyor to the 
wrapping conveyor 2 along which the wrapping of the articles is performed, 
the wrapped article then being carried off by the receiving conveyor. 
An endless transport means 4 carries, for instance, two wrapping bars 5a 
and 5b. 
The wrapping material feeding means 6 supplies the wrapping material pieces 
7a and 7b. The articles to be wrap packaged are shown as 8a and 8b. 
As seen from FIG. 1, an article 8a to be wrapped, is transferred from the 
conveyor 1 to the conveyor 2. In the meanwhile the wrapping material piece 
7a is fed by the conveyor 6, which places the leading edge of the wrapping 
material between the bottom of the article 8 and the conveyor 2. 
In FIG. 2, the whole article is placed on the conveyor 2 with the leading 
part of the wrapping material situated between the bottom of the article 
8a and the transport surface of the conveyor 2, while the wrapping bar 5a, 
suitably synchronised, intercepts the wrapping material piece 7a in its 
intermediate region. 
Referring to FIG. 3, the wrapping bar 5a has begun the transport of 
wrapping material piece 7a around the article. 
As shown in FIG. 3a, the article 8a is moved forward and the transfer of 
the subsequent article 8b from the conveyor 1 to the conveyor 2 can take 
place only when the rear extremity of the wrapping material piece 7a is 
beyond the inlet end of the conveyor 2, so that the leading end of the 
said subsequent article 8b does not push the rear extremity of the 
wrapping material piece 7a against the conveyor 2, thus preventing 
movement of the wrapping material piece 7a pulled by the bar 5a. 
For this reason, the distance between the preceding package 8a and the 
subsequent package 8b must be in a given relation with the length of the 
wrapping material piece. 
This distance determines the feeding rate of the articles 8a, 8b, etc., 
defining the production capacity of the wrapping machine. 
Referring now to FIG. 3b, it is noted that, during application of the 
wrapping material piece 7a by the bar 5a around the article, the part of 
the wrapping material 7a at the back of the bar 5a touches the part of the 
wrapping material 7a ahead of the bar 5a, thus provoking adherence of the 
two contacting surfaces. 
This adherence, in its turn, brings about undesired creeping effects 
resulting principally from electrostatic charge on the wrapping material. 
In particular environmental situations, such effects could not allow for 
the correct spreading of the wrapping material piece thus making it 
impossible to use the machine with particular types of wrapping material 
or with particular lengths of the wrapping material pieces. 
In the system illustrated in FIGS. 4 and 4a, provides for early withdrawal 
of the rear part of wrapping material piece 7a, so that the step between 
the articles may be reduced in order to increase the productive capacity 
of the wrapping machine. 
The substantial difference between the two embodiments lies in the fact 
that the close loop path of the endless transport means has the upper path 
considerably higher than the top of the article to be wrapped. 
This arrangement has many drawbacks, the first of which results from the 
fact that during the phases of wrapping the article, the part of wrapping 
material piece comprised between the wrapping bar 5a and the top of the 
article, due to its forward advancement, fills with air and swells, 
causing a longitudinal tension that sometimes can withdraw the lead 
extremity of the wrapping material piece from under the article, specially 
with articles of limited weight. 
Another drawback is that the wrapping bar must be moved much quicker 
because of its longer path, thus the aforementioned swelling effect is 
increased and a correct and harmonious spreading of the wrapping material 
piece may be obstructed. 
A further disadvantage of such embodiment that prevents a correct spreading 
of the wrapping material piece around the article 8a is due to the long 
distance of the wrapping bar 5a from the surface of the article to be 
wrapped. 
The last drawback, with reference to FIG. 4a, results from the fact that 
the part of the wrapping material piece 7a that is behind the wrapping bar 
5a touches the part of the wrapping material piece 7a that is ahead of the 
wrapping bar 5a causing the same undesired effects, already described in 
the first embodiment. 
OBJECT OF THE INVENTION 
The main object of the present invention is therefore to avoid the 
drawbacks reported above. 
SUMMARY OF THE INVENTION 
The invention, provides a method of claims, resolves the problem of finding 
out a method and an apparatus for transport of the wrapping material piece 
during the wrapping phase of articles in a machine for wrapping articles 
with wrapping material pieces. 
The method of the invention is carried out in a wrapping machine 
comprising: 
a wrapping conveyor having an inlet end, outlet end and an upper surface 
between the two ends for carrying and conveying subsequent articles to be 
wrapped; 
conveying means designed to supply wrapping material for feeding, in single 
sequence, said wrapping conveyor with wrapping material pieces, placing a 
leading extremity of said wrapping material piece over the upper surface 
of said wrapping conveyor in correspondence with said inlet end; and 
wrapping means carrying wrapping bars along a path surrounding said 
wrapping conveyor designed to wrap an article, placed on said conveyor, 
with a single wrapping material piece. 
The method transport each piece of wrapping material with a plurality of 
supporting points set spaced apart from each other in the transport 
direction and linked to one another. 
The invention also proposes an apparatus for setting wrapping material 
pieces around an article during the article wrapping phase in a wrapping 
machine for wrapping articles with pieces of wrapping material, with said 
machine comprising: 
a conveyor along which the wrapping takes place, having an inlet end, an 
outlet end, and an upper surface between the two ends designed to support 
and convey subsequent articles to be wrapped; 
conveying means designed to supply the wrapping material for feeding, in a 
single sequence, the wrapping conveyor with wrapping material pieces 
placing the leading extremity of the same over the upper surface of said 
wrapping conveyor in correspondence with its inlet end; and 
wrapping means carrying wrapping bars along a path surrounding said 
wrapping conveyor designed to wrap an article, placed on said conveyor, 
with a single wrapping material piece. 
In the claimed apparatus the wrapping means include: 
a plurality of closed loop conveying means; 
at least one wrapping element carried by each of the above mentioned 
conveying means; and 
driving means designed to drive and correlate the movement of said 
conveying means. 
The following results are obtained by the use of a method and an apparatus 
of this type: 
the rear extremity of the wrapping material piece is withdrawn earlier from 
the upstream end of the conveyor thus freeing earlier the zone between the 
feeding conveyor and the wrapping conveyor; 
the part of the wrapping material piece behind the wrapping bar does not 
touch the part ahead the wrapping bar; 
the wrapping bar can move close to the surfaces to be wrapped; and 
the speed of wrapping bar can be a bit higher than the advancement speed of 
the article to be wrapped. 
The first advantage of the present invention is that the articles to be 
wrapped can be positioned closer one to another, thus reducing the space 
between the, since the rear of the wrapping material piece is withdrawn 
earlier from between the feeding and wrapping conveyors, and the machine 
productive capacity increases. 
Another advantage of the present invention is a better spreading of the 
wrapping material piece around the article in the phase of wrapping of the 
latter and the possibility to use the above mentioned machine in any 
environmental conditions and/or with any type of wrapping material and/or 
any length of wrapping material piece, since damaging effects resulting 
from a wrapping bar that is far from the surfaces to wrap and/or effects 
resulting from adherence of the wrapping material pieces one to another 
are avoided. 
DESCRIPTION OF THE PREFERRED EMBODIMENT 
With reference to FIGS. 5-13 and, in particular FIGS. 5 and 6, the wrapping 
machine is constituted by a base 10 that carries a first conveyor 11 
designed to support and feed, in single sequence, articles 14 to a second 
conveyor 12 on which the articles are wrapped; and by a third conveyor 13 
that receives the articles from the second conveyor 12 and that complete 
the wrapping thereof. 
Below said machine there is a conveyor 15 designed to feed, in succession, 
individual wrapping material pieces 16, putting their leading ends over 
the upstream end of the second conveyor 12. 
Astride of the second conveyor 12, and near to it, there is a frame 17 
including two uprights 17a, 17b, arranged in a mirror-like manner on the 
sides of the conveyor 2 and extending therealong. 
Each upright 17a, 17b, e.g. 17b defines a pair of sliding guides 18b, 19b, 
guiding respective chains 20b, 21b, each of which transports one end of 
respective plurality of wrapping bars 22a, 22b and 23a, 23b, only two of 
them being present in the indicated example. 
The other end of the bars 22a, 22b and 23a, 23b is supported by the chains 
20a, 21a, guided slidingly in respective guides 18a, 19a, defined by the 
upright 17a. 
Said chains 20a-21a, 20b-21b are moved by respective chain supporting 
wheels 24a-25a and 24b-25b that are keyed on a common driving shaft 26. 
Thus, the bars 22-23 of each pair of bars 22a-23a, 22b-23b are transported 
together. 
Arranged in the way shown in FIG. 6, the bars 22 describe a first orbit 27, 
contained in a vertical plane circumscribing the conveyor 12; while the 
bars 23 describe a second longer orbit 28, contained in a vertical plane 
preferably parallel to the previous one, and circumscribing the conveyor 
12. 
Still with reference to FIG. 6, said orbits 27 and 28 have a path I-II 
coincident, a path II-III first divergent and then convergent, a path 
III-IV coincident, and a path IV-I first divergent and then convergent; 
this causes the change of the relative distance between the single bars 
22, 23 during circulation of each pair of bars 22a-23a, 22b-23b. 
Such changeable relative distance is obtained by making the orbital path 27 
shorter than the orbital path 28, and, simultaneously, the pitch line of 
the driving wheel 24 shorter than the one of the wheel 25, and making both 
wheels 24 and 25 rotate with the same angular speed in order to compensate 
the difference of the path of the chains 20, 21. 
With such arrangement, it is possible to change relative distance between 
the reciprocal bars 22, 23 of each pair of bars 22a-23a, 22b-23b by 
shifting one of them in respect to the other; it is also possible to 
change the orbital speed of the pair of bars 22a-23a, 22b-23b or the speed 
of a single bar in respect to the other, providing for replacement of one 
or both driving wheels with others of different pitch line. 
The wrapping machine is also equipped with a kinematic mechanism (not shown 
because it is not part of the subject of the present invention) such that 
it synchronises the movements of the three conveyors 11, 12, 13, of the 
carrier 15, and of the shaft 26 so as to obtain a synchronisation for the 
proceeding articles 14, for the wrapping material pieces 16 being fed and 
for the pair of wrapping bars 22, 23. 
With reference to FIGS. 7 to 13, that illustrate the principal operative 
phases of the wrapping of an article in sequence, the wrapping machine 
feeds the articles 14a, 14b to the conveyor 12 by the conveyor 11 in 
sequence. 
As is shown in FIG. 7, an article 14a is situated over the two conveyors 11 
and 12, and the leading extremity of a wrapping material piece 16a is so 
placed as to be interposed between the bottom of the article 14a and the 
transport surface of the conveyor 12. 
As is shown in FIG. 8, the leading extremity of the wrapping material piece 
16a is interposed between the bottom of the article 14a and the transport 
surface of the conveyor 12; when the whole article 14a is on the conveyor 
12, the wrapping bar 22a comes into contact with the wrapping material 
piece being fed, while the bar 23a remains slightly behind. 
As is shown in FIG. 9, the bar 22a spreads the wrapping material 16a on the 
back facing of the article. 
The bar 23a, also interposed between the two conveyors 11 and 12, has come 
in contact with and raised the wrapping material piece. A subsequent 
article 14b on the conveyor 11 behind the article 14a is moved towards the 
conveyor 12 by the conveyor 11. 
With reference to FIG. 10, the rear extremity of the wrapping material 16a 
is already above the level of the conveyors 11 and 12, thus freeing this 
zone for the feeding of the subsequent article 14b. 
Comparing this arrangement with the one illustrated in FIG. 3a, relative to 
the known technique, the new arrangement increases the portion of the 
wrapping material that is withdrawn, thus allowing for the reduction of 
the space between the articles to be wrapped; in comparison with FIG. 4, 
also related to the known technique, the wrapping bar moves close to the 
surface of the article, improving the spreading of the wrapping material 
piece thereon. 
As seen from FIG. 11, the wrapping material piece 16a is carried and 
transported by the bars 22a, 23a that define its linear segmented 
configuration. 
In comparison with the conformation illustrated in FIG. 3b, the segmented 
conformation of the web in FIG. 11 prevents the contact or overlapping of 
the parts of the wrapping material piece behind and before the bar 22, 
thus eliminating the undesired effects reported earlier; comparing the 
invention with FIGS. 4a, also illustrating the known technique, the 
wrapping bar appears to be closer to the upper surface of the article, 
also avoiding the disadvantages reported earlier. 
With reference to FIGS. 12, the bar 22a, together with the bar 23a, has 
partially wrapped the article 14a and has brought the rear extremity of 
the wrapping material 16a to pass between the conveyors 12 and 13, then 
positioning it below the transport surface of the same. 
The subsequent article 14b is placed on the conveyors 11 and 12, the 
leading extremity of a subsequent wrapping material 16b is situated below 
the bottom of the same article and the transport surface of the conveyor 
12; a subsequent pair of wrapping bars 22b, 23b, moving in phase relation 
with the article 14b that is now advancing as well as with the wrapping 
material piece 16b being fed, entrain the new piece of wrapping material; 
the conditions illustrated in FIG. 7 relative to the article 14a, are thus 
repeated and the operating cycle may take place again. 
With reference to FIG. 13, the article 14a can be seen to be transported 
from the conveyor 12 to the conveyor 13 and in this passage the rear 
extremity of the wrapping material piece 16a is placed below the leading 
extremity of the same wrapping material piece 16a, thus completing the 
wrapping of the article 14a. 
The article 14b proceeds and, as for the previous article, the leading 
extremity of a subsequent wrapping material piece 16b has been interposed 
between the bottom of the article and the transport surface of the 
conveyor 12.