Compacting apparatus of rolled plastic films

The apparatus serves to squeeze out air bubbles entrained between layers of rolled plastic films by pneumatically compacting so as to decrease the cloudiness in the appearance of a transparent plastic film roll. The apparatus comprises a base shaft, a tiltable trough to receive and discharge film rolls, and a movable drum which envelopes the film rolls on the trough as engaged with the base shaft with air-tightness. The space containing the film rolls received on the trough are enclosed air-tightly by the drum and base shaft engaged together and pressurized by introducing compressed air to squeeze out air bubbles out of the film rolls and then the drum is disengaged from the base shaft followed by tilting of the trough to discharge the film rolls.

BACKGROUND OF THE INVENTION 
The present invention relates to an apparatus for compacting rolled plastic 
films or, more particularly, to an apparatus which is used for 
pneumatically compacting a roll of plastic films from outside to exclude 
or squeeze out any air bubbles unavoidably entrained between layers of the 
film in the winding-up process of the roll so that the cloudiness in the 
appearance of the roll can be reduced to increase the value of the rolled 
plastic films as a commercial product. 
The above mentioned phenomenon of air entrainment in a roll of plastic 
films is one of the serious problems in the manufacture of transparent 
plastic films which are produced without exception in the form of film 
rolls because rolls containing many air bubbles between layers of 
transparent plastic films exhibit cloudy appearance to greatly decrease 
the value as a commercial product. Although entrainment of air bubbles can 
be reduced to some extent by improvements in the winding-up process of the 
plastic films into rolls, no solution can be obtained for completely 
eliminating entrainment of air bubbles between layers of rolled plastic 
films. Accordingly, it is desirable to develop an efficient apparatus for 
excluding or squeezing out the air bubbles by compacting from outside of 
the plastic film roll after winding up. No information is available, 
however, for such an apparatus suitable for industrial use insofar as the 
inventors are aware. 
SUMMARY OF THE INVENTION 
The present invention accordingly has an object to provide an apparatus for 
compacting a roll of plastic films from outside pneumatically in order to 
squeeze out any air bubbles entrained between layers of the plastic films. 
In particular, the invention has an object to provide such an apparatus on 
which a plural number of plastic film rolls can be treated simultaneously 
as a group. 
Thus, the apparatus of the invention for pneumatically compacting a roll of 
plastic films comprises: 
(a) a base stand having an elongated plan; 
(b) a hollow cylindrical base shaft fixedly mounted in a horizontal 
disposition on or above the base stand along the longitudinal direction of 
the base stand and connected at one end to a means for air supply and 
evacuation, the other end being open; 
(c) a trough for receiving rolls of plastic films pivotally connected to 
the base shaft at one end in a tiltable manner in the circumferential 
direction, the other end thereof extending toward the longitudinal 
direction of the base stand; 
(d) an elongated cylindrical drum closed at one end remote from the base 
shaft and mounted above the base stand in a movable manner along the 
longitudinal direction of the base stand to envelope the trough when moved 
toward the base shaft; and 
(e) a means for fastening the open end of the elongated cylindrical drum to 
the open end of the base shaft and air-tightly connecting the same 
together.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In the following, the apparatus of the present invention is described in 
more detail with reference to the accompanying drawing, which, however, 
should not be construed to limit the scope of the invention in any way. 
In the figures of the accompanying drawing, the base stand 1 having an 
elongated rectangular plan is provided with two sets of wheels 2,2 and 
3,3, by means of which the base stand 1 can be moved in the longitudinal 
direction and transverse direction, respectively. A cylindrical base shaft 
4 is fixedly mounted above the base stand 1 lying in the longitudinal 
direction of the base stand 1. The base shaft 4 is provided inside with a 
mechanism for switching air supply into and evacuation from the base shaft 
4 (not shown in the figure). The base shaft 4 is connected at one end 
(right-hand end on FIG. 1) to an air supply duct 5 and evacuation duct 6 
while the other end is open. A tiltable trough 7 is positioned in such a 
disposition that the bottom thereof is in parallel to but aside the axial 
line of the base shaft 4 at a side toward the viewer of FIG. 1. The trough 
7 is pivotally connected at the pivotal axis 8 in parallel to the axial 
line of the base shaft 4 in such a manner that the trough 7 can be tilted 
within a range of 90.degree. angle around the axis 8 (see FIG. 3) to 
receive and discharge film rolls. The trough 7 is formed of three parts 
including the bottom trough 9 having a rectangular cross section, a first 
side plate 10 at the discharge side of the rolled film, of which the upper 
part is upright and the lower part is aslant to make the width of the 
trough 7 wider in the upper part than at the bottom trough 9, and a second 
side plate 11 at the receiving side of the trough 7, which is aslant to 
make the width of the trough 7 wider in the upper part than in the bottom 
trough 9 with a further bent along about the center line to decrease the 
inclination of the plate in the upper half thereof. The upper periphery of 
the second side plate 11 is at a height lower than that of the first side 
plate 10. In this manner, each of the plastic film rolls is received at 
such a height that the axis of the roll is at a height some-what higher 
than the axis of the base shaft 4. 
The base stand 1 is provided on the upper surface thereof with two rails 
12,12 running in parallel symmetrically relative to the center line of the 
base stand 1. A wheeled cart 14 is mounted on these rails 12,12 so as to 
be movable in the right and left directions in FIG. 1 and a cylindrical 
drum 13 is supported by the cart 14. The wheeled cart 14 can be moved 
right and left on the rails 12,12 by means of the driving mechanism 
composed of an electric motor 15, transmission gear box 16 and chain 17. 
The cylindrical drum 13 is closed at one end with an end plate 18 which is 
provided at about the center inside with a supporting rod 20 horizontally 
extending to the open end 19 of the cylindrical drum 13 in a 
cantilever-like manner. The height of this supporting rod 20 is somewhat 
higher than the axis of the cylindrical drum 13. The drum wall 21 of the 
cylindrical drum 13 is coaxial with the base shaft 4 and, when the trough 
7 is positioned to receive a roll of plastic films R, is at a position to 
envelope the outer surface of the roll R. The open end 19 of the 
cylindrical rod 13 has such a configuration and is at such a position that 
the open end 22 of the base shaft 4 can be inserted thereinto and 
withdrawn therefrom. When the open end 22 of the base shaft 4 is inserted 
into the open end 19 of the cylindrical drum 13, they are in contact with 
each other with air-tightness by a mechanism of a fluid pressure-operated 
lockring cylinder device 23. A tilting mechanism 24, which is composed of 
a fluid-pressure cylinder 25 and a wheeled pusher rod 26 held on the end 
of a plunger of the cylinder 25, serves to tilt the trough 7 in such a 
manner that the trough 7 can be tilted by an angle of 90.degree. or 
smaller when the bottom trough 9 is pushed by the pusher rod 26 which is 
moved linearly by pressurizing the fluid-pressure cylinder 25. 
As is illustrated in FIG. 2, a receiving table 27 and a discharge table 28 
each having an inclination and supported by the base stand 1 are provided 
on the receiving side and discharge side, respectively, of the trough 7 so 
as to utilize gravity for the movement of a film roll toward and from the 
trough 7. A set of pivotally supported alignment-detecting arms 29 are 
provided in a swingable manner within a vertical plane above the discharge 
side of the base stand 1 in a lattice-like arrangement with a span to 
cover all of the film rolls R . . . to be aligned in a row. 
In the following, a description is given on the movement of each of the 
above described parts. In FIG. 1, the starting position of the cylindrical 
drum 13 is shown by the solid lines and a plural number of film rolls R . 
. . each having an appropriate film width by cutting in and transferred 
from a film roll processing machine (not shown in the figure) are received 
on the receiving table 27 as aligned in a row. Each of the film rolls R . 
. . rolls down on the inclined receiving table 27 to be received in the 
trough 7. The alignment-detecting arms 29 are laid down on the film rolls 
R . . . in the trough 7 and serve to detect correct alignment of the rolls 
R . . . in the trough 7. Then the alignment-detecting arms 29 are swung up 
and the electric motor 15 is energized to slide the cylindrical drum 13 
rightwardly on FIG. 1 by means of the wheeled cart 14 to the position 
indicated by the chain lines in the figure so that the open end 19 thereof 
becomes engaged with the open end 22 of the base shaft 4. The supporting 
rod 20 held on the end plate 18 of the cylindrical drum 13 is accordingly 
inserted into the cardboard-made core tubes of the film rolls R . . . 
aligned in a row so that the film rolls R . . . are secured on the 
supporting rod 20 with stability. With the electric motor 15 interrupted, 
the open end 19 of the cylindrical drum 13 and the open end 22 of the base 
shaft 4 are air-tightly contacted and fastened together by operating the 
lock-ring cylinder device 23. 
In the next place, the air-supply and evacuating mechanism built in the 
base shaft 4 is switched to work for air supply and the cylindrical drum 
13 is pressurized by introducing compressed air through the air supply 
duct 5. The cylindrical drum 13 is maintained for a while or, usually, 20 
to 40 seconds in this pressurized state so that each of the film rolls R 
is compacted by the air pressure and air bubbles entrained between layers 
of the rolled film are squeezed out. After lapse of the time, the 
air-supply and evacuating mechanism built in the base shaft 4 is switched 
to work for evacuation to discharge the air inside the cylindrical drum 13 
out of the evacuation duct 6. When discharge of the air has been 
completed, the lock-ring cylinder device 23 is released and the open end 
19 of the cylindrical drum 13 is disengaged from the open end 22 of the 
base shaft 4. Then, the electric motor 15 is energized to rotate in the 
reverse direction so as to slide the cylindrical drum 13 on the wheeled 
cart 14 leftwardly on FIG. 1. 
When the cylindrical drum 13 thus slided has reached the starting position 
indicated by the solid lines on FIG. 1, the tilting mechanism 24 is 
operated so that the trough 7 is tilted by 90.degree. around the axis 8 as 
being pushed by the advancing movement of the wheeled pusher rod 26 to 
reach the tilted position indicated by the chain lines on FIG. 3. As a 
consequence of the tilting movement of the trough 7, the film rolls R . . 
. on the trough 7 are each released on to the inclined discharge table 28 
and roll down thereon to be received by a suitable transferring means such 
as a belt conveyor (not shown in the figure) to be transferred to a 
working station for packaging and shipping. 
The tilting mechanism 24 of the trough 7 is again operated so as to bring 
the trough 7 to the starting untilted position where the trough 7 is ready 
to receive another set of film rolls for the next run of the compacting 
treatment. By repeating the above described cycle of the movement of each 
part, numbers of film rolls can be treated very efficiently to be imparted 
with greatly improved appearance without cloudiness. 
It is of course that the above described sequence of the movements of the 
respective parts in the inventive apparatus can be readily and fully 
automatized by utilizing a conventional system for sequence control 
involving various mechanical control devices using cams and the like, 
electric control devices using electromagnetic relays, timers and the 
like, electronic sequence controllers using logic sequence circuits with 
semiconductor devices and computer programs, and so on. Therefore, the 
efficiency of the inventive apparatus can be improved so much in 
accordance with the extent of the automatization to give a great advantage 
to the industry of plastic film manufacture. 
The above described compacting apparatus of the invention is applicable to 
a rolled film of any plastic resins having transparency without particular 
limitations. The treatment by use of the inventive apparatus gives 
particularly satisfactory results when the plastic resin is a plasticized 
polyvinyl chloride or the like resin, which may be colored or uncolored, 
including homopolymeric polyvinyl chloride resins, polyvinylidene chloride 
resins, chlorinated polyvinyl chloride resins, copolymeric resins of vinyl 
chloride and vinyl acetate and the like compounded with a substantial 
amount, e.g., 10 to 300 parts by weight or, preferably, 40 to 100 parts by 
weight per 100 parts by weight of the resin, of a plasticizer. The plastic 
film should have a thickness of 5 to 30 .mu.m although there is no reason 
that the apparatus is not applicable to a plastic films having a smaller 
thickness than above. 
Following is an example to show the cloudiness-reducing effect when a 
plastic film roll is treated in the inventive apparatus. As the standard 
conditions for the pneumatic compacting of film rolls in the inventive 
apparatus, the compacting air pressure is usually in the range from 5 to 
20 kg/cm.sup.2 G or, preferably from 5.0 to 6.0 kg/cm.sup.2 G at a 
temperature of 20.degree. to 40.degree. C. and the length of time for 
compacting is 30 to 50 seconds although the length of this time depends on 
the pneumatic pressure and the desired degree of cloudiness reduction 
assuming that the temperature is the same. The cloudiness of a film roll 
can be visually inspected by holding the film roll to the illuminating 
light from a 40 watts fluorescent lamp 1.5 meters above the roll and 
looking through the roll. When the light is reflected in a mirror-like 
manner on the surface area of the roll smaller than 7% of the whole 
surface, which percentage is taken as a measure of the cloudiness, the 
film roll is acceptable as being substantially free from cloudiness. 
EXAMPLE 
A plasticized polyvinyl chloride resin composition was prepared by 
compounding 100 parts by weight of a homopolymeric polyvinyl chloride 
resin having an average degree of polymerization of about 1300, 15 parts 
by weight of a plasticizer (D610A, a product by Kyowa Hakko Co.) and 10 
parts by weight of an epoxidated soybean oil. The resin composition was 
shaped into a film of 17 .mu.m thickness by T-die extrusion at 200.degree. 
C. and the film was wound on paper cores of 3 inches diameter into film 
rolls for film lengths of 500 meters, 1000 meters and 1500 meters. These 
film rolls were all very cloudy and not suitable for commercial purpose. 
Pneumatic compacting treatment of these film rolls was performed using the 
inventive apparatus for 100 film rolls for each of the film lengths at 
30.degree. C. for 40 seconds under an air pressure of 5 kg/cm.sup.2 G to 
find that the cloudiness was 5% or smaller in all of the film rolls to be 
acceptable as a commercial product.