Film tube gusset forming machine

A machine for converting tubular plastic film from flat fold to pleated fold cross section which includes self-contained radio controlled inflating capsule positioned within the tube to inflate it as the gussets are being formed by conventional forming or plowing mechanism.

BACKGROUND OF THE INVENTION 
This invention relates generally to equipment for forming gussets in 
tubular plastic film, and more particularly to a film gusseting machine 
that utilizes a radio operated capsule disposed within the blown portion 
of the film for inflating the film as it is being advanced while the 
gussets are being formed. 
SUMMARY OF THE INVENTION 
The object of the invention to provide, in a film tube gusseting machine, a 
device for maintaining within the portion of the film being gusseted an 
inflation pressure sufficient to permit the gusset forming means to 
function properly. 
A more specific object of the invention is the provision, in a gusset 
forming machine, of a means for maintaining the blown film at the proper 
inflation without having to puncture or damage the film in any way. 
A more specific object of the invention is the provision, in a device in 
the type described, of a self contained inflating capsule mechanism that 
can be positioned within the blown portion of the film and which can be 
controlled by a radio transmitter located outside of the film. 
Another specific object of the invention is the provision, in a device in 
the type described, of a radio controlled capsule for inflating the film 
which is positioned within the film and which is controlled automatically 
by means of a sensing device engagable with the outside surface of the 
film. 
These and other objects of the invention will be apparent from the 
examination of the following description and drawings.

DESCRIPTION OF THE PRIOR ART 
The usual means for forming pleats or gussets in tubular film stock is to 
inflate a portion of the film as it passes between separate sets of nip 
rolls and then fold or plow in the sides of the film by mechanical plows 
or forming devices. 
One of the problems encountered in this type of operation is that of 
maintaining adequate pressure within the portion of the film being 
gusseted so that the gusset forming devices can function properly and 
unformly. 
In the past it has been necessary intermittently to puncture that portion 
of the film being gusseted and then insert sufficient air by means of a 
needle or similar mechanism. This, of course, damages certain portions of 
the film requiring those portions to be discarded. 
DESCRIPTION OF THE PREFERRED EMBODIMENT 
The present invention provides a means for insuring a uniform inflation 
pressure at all times within the blown portion of the film which is being 
gusseted without damaging the film in any way. 
Referring now to the drawings for a better understanding of the invention, 
and first to FIGS. 3 and 4, it will be seen that the pleated fold film 
with gussets G, indicated at PF in FIG. 4, can be formed from conventional 
flat fold film stock indicated at FF in FIG. 3. 
Now referring to FIG. 1 of the drawings it will be seen that the novel 
machine embodying features of the invention comprises a frame assembly, 
indicated generally at FS, which includes a frame indicated generally at 
10. 
FIG. 10 includes a pair of front and rear supports, 12 and 14, for holding 
unfinished tubular film stock roll TS and a finished film stock roll PF, 
respectively. 
Mounted on the frame between the film supporting means is a gusseting or 
pleating assembly indicated generally at PA which includes first and 
second set of nip rolls or film feed rolls 16 and 18, respectively, which 
are positioned inwardly adjacent the front and rear film supports 12 and 
14. 
The portion of the film located between the first and second sets of nip 
rolls is inflated in a manner described later in the specification. As the 
tubular film is inflated it is necessary to restrain the film and maintain 
it in a predetermined shape, which in the present case is preferably 
diamond shaped, as seen from the side and generally rectangular as, seen 
from the top, and illustrated in the schematic view of FIG. 2. 
The maintaining of the blown film in a predetermined shape is accomplished 
by upper and lower sets of restraining boards 20 and 22, respectively, 
which are pivotally connected by means of pivotal connections 24 and arms 
26 to upper and lower portions of the frame. These restraining boards 
serve as a mold to maintain the film in a specific predetermined contour 
as it is being advanced between the first and second set of nip rolls. 
In order to monitor and control the degree of inflation within the film 
there is provided a sensing device, indicated generally at R, which is 
linked to one of the upper restraining boards 20 by means of a linkage 
indicated generally 28. 
The actual forming of the pleats or gussets in opposite sides of the 
tubular film is accomplished by a pair preferably triangular gusset 
forming boards or plows 30 which are pivotally connected to frame F by 
means of a sub-assembly indicated generally at 32, and illustrated in FIG. 
1. 
As previously mentioned, the unique feature of the present invention, which 
distinguishes it from all known prior art, is the mechanism for inflating 
that portion of the tubular plastic film being advanced between the nip 
rolls and maintaining it at a proper inflation level so the gusset forming 
boards or plows 32 will be able to form the film into the desired gusseted 
or pleated form. 
In the present invention the inflation of the tubular film is accomplished 
by means of a self contained cannister or capsule, indicated generally at 
40, which is positioned within the film tube itsefl and is generally 
cylindrical in shape, so that as the film moves forward the capsule can 
stay in position at the bottom of the film portion between the forming 
boards, as shown in FIG. 2. 
The capsule 40 has a generally cylindrical side wall or body 50 with a pair 
of removable end walls 54 which are held together by axially extended tie 
rods 54. 
Positioned within the capsule 40, as best seen in FIG. 5, is a valve 42, 
mounted in one of the end walls 52; a motor 44; a battery 46 for powering 
the motor; and a receiver 48 for operating the motor and valve. 
As previously mentioned, the sensing device, indicated generally at R, and 
illustrated in FIG. 2, includes a radio transmitter which, after being 
activated by the linkage 28, determines that more air is needed to 
maintain adequate inflation pressure between the blown portion of the 
film, transmits the appropriate message to the receiver 48 within the 
capsule 40 causing the motor to open the valve and admit the appropriate 
amount of air from within the capsule to within the blown portion of the 
film. 
Thus, the invention provides a unique means for maintaining adequate 
pressure on film to permit the gusseting operation, and, at the same time, 
does not cause any damage to the film as the gussets are being formed.