Apparatus and method for opening and transporting a flat-folded tube of flexible material

The operating speed of apparatus for opening and guiding a flat-folded tube of plastic wrapping film, especially a tube of heat shrinkable plastic film, which include a spreader mandrel for opening the tube and drive rollers or belts for transporting and guiding the tube over the spreader mandrel, is increased, and the overall efficiency of operation of the apparatus is improved, by providing an extension piece with a pair of driving rollers or belts which operate independently of the driving rollers associated with the spreader mandrel, at the downstream end of the mandrel. By cutting the tube at the downstream end of the mandrel, after the tube is conveyed over the extension piece and in contact with the extension piece drive rollers or belts, the cut tube section can be slid over the objects to be packaged at rates of from 2 to 5 times faster than previously possible. The extension piece can be fixedly mounted to the mandrel or it may be oscillatingly suspended from the mandrel. In the latter case, the object to be packaged need not be stationary when the opened cut tube section is being fitted thereover.

This invention relates to an apparatus and method for guiding, to an object 
to be stored or packaged therein, a tube of flexible material. More 
particularly, this invention relates to an apparatus and method for 
opening and transporting a flat-folded tube of plastic film, preferably a 
heat-shrinkable plastic film, over a spreader mandrel and to an item or 
product to be packaged or stored within the plastic film. 
The present invention is directed to an improvement in the method and 
apparatus disclosed in Netherlands patent application No. 7,810,938, 
laid-open for examination on May 7, 1980. According to this Netherlands 
patent application, a flat-folded coiled plastic tube is fed to an 
apparatus including a spreader mandrel on which the tube is opened and 
transported to the object to be packaged by appropriately placed drive 
rollers. In particular, the opening and conveying device disclosed in the 
Netherlands patent includes a spreader mandrel provided with two or more 
diametrically opposed recesses in each of which are mounted on parallel 
axes which are perpendicular to the longitudinal axis of the spreader 
mandrel a pair of rollers mounted such that the outer periphery of each 
roller coincides with the outer surface of the spreader mandrel. At least 
one corresponding pair of drivable rollers is provided to cooperate with 
the first pair of rollers for engaging the opened tube in the recesses 
such that the tube is supported by and conveyed by the rotation of the 
drivable rollers as the tube passes through the nip formed between the 
rollers located within the recesses and the drivable rollers which 
protrude slightly into the recesses. A cutting device is provided at the 
downstream or exit end of the spreader mandrel to cut off an opened 
section of tube. 
While the device disclosed in the Netherlands patent provides an improved 
means for opening a flat-folded plastic tube and conveying the opened tube 
to the object to be packaged, there are several drawbacks in this known 
method and apparatus. For example, the drivable rollers are required to 
both feed and convey the tube over the spreader mandrel and to convey the 
opened tube to the cutting means as well as to convey the tube up to the 
object to be packaged therein before the actual cutting takes place. The 
speed of the drivable rollers is limited to a maximum value determined by 
the strength of the tubing material with respect to overcoming the 
resistance to the unwinding of the supply roll of the flat-folded tube and 
with regard to the operation of slipping the flattened tube over the nose 
of the mandrel in the spreading operation. An additional drawback is that 
the object to be packaged must be substantially stationary under the 
mandrel while the section of tube to be subsequently cut-off is slipped 
around the product and while the actual cut of the tube section is made. 
Accordingly, it is an object of the present invention to increase the speed 
at which the known opening and conveying apparatus can operate and to 
correspondingly increase the rate at which objects can be packaged using 
such apparatus. 
It is correspondingly an object of this invention to provide an improved 
method for opening a flat tube of flexible heat-shrinkable plastic film 
and fitting the opened tube over an object to be stored or packaged 
therein. 
It is also an object of the present invention to provide a method and 
apparatus for packaging objects in a tube of heat-shrinkable plastic film 
material wherein the object need not be satisfactory while being wrapped 
by the plastic film tube and wherein the object need not be in a position 
directly aligned with the longitudinal axis of the spreader mandrel used 
to open and convey the plastic tube to the object. 
These and other objects of the present invention which will become more 
readily apparent from the following detailed description of preferred 
embodiments and with the aid of the accompanying drawing are provided by 
an improvement in apparatus for guiding a flat-folded tube of flexible 
film from a supply source over a spreader mandrel to open the plastic tube 
whereby the opened tube may be fitted over a product to be packaged or 
stored therein and wherein the spreader mandrel includes means for 
conveying the opened plastic tube to and beyond its downstream end, means 
for cutting off an opened tube section at the downstream end of the 
spreader mandrel, such improvement including an extension piece for the 
spreader mandrel mounted downstream of the cutting means and providing 
means for guiding the opened cut tube to the object to be packaged or 
stored therein, and drive means for driving the opened cut tube beyond the 
extension piece and over the object to be packaged or stored therein. The 
drive means can be in the form of rollers, belts, chains and similar 
transporting devices. 
Generally, as disclosed in the Netherlands patent application No. 
7,810,938, the means for conveying the plastic tube to the downstream end 
of the spreader mandrel preferably includes at least a first pair of 
rollers mounted on axes located radially inwardly of the outer periphery 
of the mandrel and perpendicular to and on opposite sides of the 
longitudinal axis of the mandrel and at least a corresponding pair of 
drivable rollers mounted on axes parallel to and downstream, in the 
direction of travel of the plastic tube, of the axes of the first pair of 
rollers, the axes of the drivable rollers each being located radially 
outwardly and an opposite sides of the outer periphery of the mandrel, 
whereby each of the rollers of the first pair of rollers is in peripheral 
linear contact with the corresponding one of the drivable rollers, such 
lines of peripheral contact being located at the outer periphery of the 
mandrel. Alternately, drive belts or other similar drive means can be used 
to convey and transport the opened plastic tube over the length of the 
spreader mandrel to the cutting means. 
In one embodiment of this device, means are provided for continuously 
driving the drive means, e.g. a pair of drivable rollers, and for moving 
the drive means in and out of contact with the mandrel extension piece. In 
an alternative embodiment, the drive means is only intermittently driven 
and can be maintained in contact with the mandrel extension piece 
throughout the operation. 
The mandrel extension piece can be mounted in a stationary or fixed 
position with regard to the mandrel or in a particular embodiment of the 
invention, the mandrel extension piece can be mounted for oscillation with 
respect to the longitudinal axis of the mandrel. In this embodiment, means 
are provided for oscillating the mandrel extension piece and for 
correspondingly oscillating the drive means. In this latter embodiment, 
the object to be packaged can be tracked by the oscillating extension 
piece and, accordingly, the object need not be stationary nor located 
directly aligned with the longitudinal axis of the spreader mandrel in 
order for the opened and cut section of tube to be placed over the object. 
The present invention also provides a method for fitting an opened tube of 
flexible heat-shrinkable plastic film over an object to be stored or 
packaged therein. This method includes the steps of 
(a) feeding a flat-folded tube of the plastic film over a spreader mandrel 
to spread open the flat-folded tube, 
(b) using an extension piece at the downstream end of the spreader mandrel, 
the extension piece having a length of substantially the same dimension as 
the height of the object to be stored or packaged therein, 
(c) transporting the opened tube over the spreader mandrel to the 
downstream end of the extension piece, 
(d) cutting the opened tube just beyond the downstream end of the spreader 
mandrel to form an opened cut tube section to be transported over the 
extension piece to the object, 
(e) feeding the object to a position below the extension piece, 
(f) substantially simultaneously with step (e), contacting the opened cut 
tube section with a driving device to transport and guide the opened cut 
tube section over the extension piece to and over the object, and 
(g) repeating steps (a) through (f) at least once. 
By providing the extension piece at the downstream or exit end of the 
spreader mandrel and beyond the cutting device and by including separate 
drive means for the cut-off section of the opened tube to press against 
and convey the cut-off section of tubing, there is a separation between 
the feeding of the plastic tube material onto the spreader mandrel on the 
one hand and the slipping of the cut-off section of tubing over and around 
the object, on the other hand. Accordingly, the drive means for the 
cut-off section of tubing associated with the extension piece can be 
driven at high speed so that the slipping of the tubing onto the object 
can be accomplished in a much shorter time than the feed operation. By 
virtue of this speed differential, the objects to be packaged need to be 
maintained in a stationary position, if at all, for a shorter time than in 
the known device whereby the overall speed of conveyance and the packaging 
speed can be proportionately increased. Furthermore, when the objects to 
be packaged have a tapering top, such as in the case of many types of 
bottles, or other types of conical objects, it becomes possible, due to 
the faster rate at which the opened cut tube section can be transported, 
to move the objects continuously under the mandrel and extension piece 
therefor. 
As previously noted, it is possible in one embodiment of the invention to 
cause the drive means associated with the extension piece to be 
continuously driven and to provide means to bring the drive means into and 
out of contact with the extension of the mandrel. According to this 
preferred embodiment, there will be no loss of time while the drive means 
come up to speed as in the case of intermittent operation. It is only 
necessary that the drive means, e.g. rollers or belts, must be withdrawn 
from the extension piece after an opened cut tube section is conveyed over 
and beyond the extension piece whereby a new tubing section can be fed 
over the extension piece and the operation continued in this fashion. 
As also mentioned above, in one preferred embodiment of the invention, the 
extension piece is suspended from the spreader mandrel in a fashion to be 
able to oscillate about the longitudinal axis of the speader mandrel, e.g. 
as a pendulum. The extension piece can then swing to a predetermined 
degree, whereby slight deviations in the position of the object, i.e. when 
it is not exactly coaxial with the mandrel, can be tolerated. Naturally, 
in this case, the drive means associated with the extension piece must 
also be able to accompany this oscillating movement. This embodiment 
therefor not only enables continuous feeding and packaging of objects 
which taper towards their top end, but also non-tapering objects or 
objects which are as wide or wider at their top end than at their bottom 
end. 
Any suitable drive means may be used to transport and convey the cut-off 
section of tubing over the mandrel extension piece to and over the object 
to be packaged. These drive means are conveniently provided by one or more 
pairs of drivable rollers mounted on axes perpendicular to the 
longitudinal axis of the spreader mandrel, and being located adjacent the 
extension piece, i.e. either in direct contact with, or movable to come 
into contact with, the extension piece, so that the plastic tubing can be 
conveyed by rotation of the drivable rollers over and beyond the extension 
piece. Alternately, the drivable rollers can be replaced by suitable drive 
belts or chains, driven by any suitable means. The drive belts or chains 
should not, of course, include any protrusions or rough surfaces which 
could puncture, tear or cause damage to the plastic tubing. Furthermore, 
the belts or chains can be made relatively wide or narrow with respect to 
the width of the tubing and can extend over substantially the entire 
length of, or over only a fraction of the length of the cut-off tubing 
section. It is only necessary that sufficient contact be made between the 
drive means and the cut-off tubing section to positively engage the latter 
to ensure that the cut-off tubing section will be transported without 
slippage.

The FIGURE shows the spreader mandrel 10, which may be fabrciated from hard 
material, e.g. plastic, metal, etc. having a smooth outer surface so as 
not to tear or scratch the plastic film of the flat-folded tube 12 which 
comes into contact therewith. The mandrel serves to open and spread the 
sides of the flat-folded tube 12 of plastic film, preferably a 
heat-shrinkable plastic film, which is supplied from a suitable supply 
source, such as coiled on supply roll 13, which can rotate on shaft 13a in 
frame 15. 
Mandrel 10 is provided at two diametrically opposed portions around its 
outer periphery 10c and intermediate its tapered feed or inlet end 10a and 
its downstream or exit end 10b with recesses 14. These recesses each house 
a first pair of rollers 16a and an additional pair of rollers 16b. Rollers 
16a and rollers 16b are rotatably mounted on parallel axes which are 
located radially inwardly of the outer periphery 10c and perpendicular to 
and on opposite sides of the longitudinal axis CL of the mandrel. 
Mandrel 10 is mounted vertically in the space between a corresponding pair 
of drivable rollers 17 rotatably mounted on axes 18 in frame 15. Axes 18 
are parallel to each other and also to the axes of rollers 16a and rollers 
16b. As seen in the FIGURE axes 18 are located radially outwardly and on 
opposite sides of the outer periphery of mandrel 10, and are mounted in a 
common horizontal plane which is located downstream of the horizontal 
plane passing through lower rollers 16b. The diameter of each of drivable 
rollers 17 is such that each of these rollers protrude slightly into the 
respective recesses 14 and make peripheral linear contact with the 
respective ones of the upper rollers 16a and lower rollers 16b with the 
lines of linear contact being located substantially at the outer periphery 
of mandrel 10. That is, the gap or space between the drivable rollers 17 
is somewhat smaller than the distance between the outermost parts of 
rollers 16a. Accordingly, it can be seen that the spreader mandrel is 
supported with its upper rollers 16a resting on the pair of drivable 
rollers 17. 
The lower rollers 16b are optional, but when they are used, they serve as 
auxiliary support rollers and prevent undesirable oscillation of the 
mandrel between rollers 17. Rollers 16b can be replaced or supplemented 
with auxiliary support rollers x and/or y (shown by dotted lines) mounted 
on frame 15 to provide the necessary stability. These auxiliary support 
rollers x and y can press elastically against the outer surface 10c of the 
mandrel. 
The tube 12 to be spread open can be slipped with its downward hanging end 
onto the top of the mandrel 10 until this end has come between drivable 
rollers 17 and rollers 16a and 16b. When rollers 17 are driven in the 
direction of the arrow, by means such as electric motor 19, for example, 
or, alternatively, by an hydraulic or pneumatic motor, the tube is drawn 
downward over the mandrel which is typically cylindrical. Up to this 
point, the device described is similar to that described in the 
Netherlands patent application mentioned above. 
According to the invention, mandrel 10 is provided with an extension piece 
23 projecting beyond auxiliary rollers y if present. The height of this 
extension, i.e. the length along the center line CL of the mandrel, is 
approximately equal to the height of the objects to be packaged. In the 
illustrated embodiment, as shown in solid lines, extension piece 23 is 
fixed firmly to the mandrel 10 and can guide an opened cut tube section to 
the object to be stored or packaged therein. 
At or near the lower or downstream end 23b of the extension piece 23 a 
second pair of drivable rollers 24 are mounted rotatably on axes 26 which 
are in diametrical opposition to each other and are perpendicular to the 
longitudinal axis CL of mandrel 10. These rollers 24 can be driven in any 
suitable manner, not shown in more detail, but about which more is said 
below, for transporting the opened cut tube beyond the extension piece and 
over the object to be packaged or stored therein. 
Between the end 10b of mandrel 10 and the upper end 23a of the extension 
pice 23 there is an annular groove 25, level with two horizontal cutting 
knives 31 mounted outside the mandrel, which can move back and forth 
horizontally in the direction of the arrows. 
Below the extension piece, a conveyor belt 42 is shown, with an object 40 
thereon. 
In operation, the apparatus works as follows: As support rollers 17 are 
driven, a section of the tube 12 which may initially be fed manually to 
the nip between rollers 16a and 17, is spread and guided with its open end 
to a point level with or slightly below rollers 24. The knives are then 
actuated, and the section of the tube which is over extension piece 23 is 
cut off. Next, rotating rollers 24 are in contact with the cut-off portion 
of the tube and move it downward to slip it over the object 40 that is fed 
into position, by conveyor belt 42, directly below the extension piece. 
The conveyor belt intermittently moves the objects fitted with a wrapper 
to one end of this belt, where they are transferred to a shrinking device, 
for example, a heat oven, where under the influence of heat, the tube 
wrapper shrinks around the object to produce the desired package. 
As soon as knives 31 have cut off the lower tube portion, rollers 17 can 
once more begin to feed a new section of tube. In the meantime, conveyor 
belt 42 moves a new object 40 into the proper position, coaxial to the 
centerline of the mandrel, and rollers 24 are actuated, which can turn at 
a much higher speed than the rollers 17 because they do not experience 
resistance from the supply roll 13 and the spreading of the tube, as in 
the case of drive rollers 17. Due to the higher speed of rollers 24, 
excessive force on the tube section is avoided. 
It is possible to drive rollers 24 continuously, and, for example, to mount 
their axes in pivoting arms (not shown), when then swing rollers 24 toward 
extension piece 23 only when an object 40 is coaxial with the mandrel. 
It is also possible to mount rollers 24 in a fixed position and to drive 
them only when an object is coaxial to the mandrel. 
Auxiliary support rollers x' can be disposed, with respect to extension 
piece 23, in the same way as support rollers at the upper end of the 
mandrel, to stabilize the mandrel extension piece. However, it is also 
possible to provide the mandrel extension piece as a component separate 
from mandrel 10 and to suspend it from mandrel 10 so that it is free to 
oscillate, for example, in a pendulum-like motion, such as shown by dotted 
lines, or the extension piece can be moved in a horizontal plane, e.g. 
parallel to the movement of the upper leg of conveyor belt 42. 
While a tube section is slipped onto mandrel 10 and while the cutting 
knives 31 are in action, the object to be packaged need not be coaxial 
with the mandrel, but can be brought up by conveyor belt 42 during this 
time. Only after knives 31 have functioned and the tube around the mandrel 
extension piece 23 has been cut must the object be coaxial to the mandrel, 
since this is the time when rollers 24 slip the plastic tube wrapping onto 
the object at high speed. During the subsequent removal of the wrapped 
object, the feeding of a fresh tube section over the mandrel can be 
initiated. In the meanwhile, still another new object is brought under the 
mandrel. As a result, the object need be stationary under the mandrel for 
a shorter time than with the known device. The average conveyor speed of 
the objects is higher. The packaging speed can, therefore, be increased by 
a factor of 2 to 5 as compared with the known device in which the 
extension piece is not provided. 
In the case of objects that taper somewhat at the top, the conveyor belt 42 
can be run continuously, so that the object actually does not stop under 
the mandrel. Due to the high driving speed of rollers 24, the cut tube 
wrapping can still be slipped onto the moving object. This is also 
possible in the case of nontapering products, particularly when mandrel 
extension piece 23 is suspended so that it is free to oscillate as 
described above. 
In place of rollers 17 and/or rollers 24 drive belts or drive chains, or 
other similar drive means can be used to convey and transport the plastic 
tubing over the spreader mandrel 10 and/or over the extension piece 23. 
Similarly, any of the auxiliary or optional rollers x, x' and y can be 
replaced or supplemented by drive belts. 
It will be understood, therefore, that while the invention has been 
described particularly with reference to preferred embodiments thereof, 
various changes may be made all within the full and intended scope of the 
claims which follow.