Machine and method for filling, introducing steam into, and sealing flexible pouches

Flexible pouches filled with product are advanced to a steaming station where steam is introduced into the pouches to remove the air therefrom. The pouches are closed and sealed while in the presence of steam and before being advanced out of the steaming station so as to prevent air from re-entering the pouches.

BACKGROUND OF THE INVENTION 
This invention relates to a packaging machine and to a method of filling 
flexible pouches with product, introducing steam into the filled pouches 
to remove the air therefrom, and then sealing the pouches. 
In the packaging of certain products, and particularly food products, the 
filled and sealed pouches are delivered to an autoclave and are heated to 
high temperatures so as to sterilize the product in the pouches. In order 
for this packaging process to be successful, it is important that the 
sealed pouch be substantially free of air when the pouch is delivered to 
the autoclave. If any significant amount of air is present in the pouch, 
the air will expand when subjected to the high temperatures in the 
autoclave and will cause the pouch to balloon, such ballooning sometimes 
destroying the seals of the pouch. Even if the pouch is not subjected to 
autoclaving, it is often desirable to remove the air from the pouch so 
that the product will be packaged in an oxygen-free environment and will 
possess a long stable shelf life. 
One known method of producing substantially air-free pouches is disclosed 
in Wilson U.S. Pat. No. 3,845,606 in which filled pouches are advanced 
through a retort containing steam and then are sealed while still in the 
retort. Another method takes place in ambient atmosphere rather than in a 
retort and involves the use of a packaging machine of the same general 
type as disclosed in Bartelt U.S. Pat. No. 2,649,674, a machine of this 
type being known in the industry under the trademark BARTELT. With such a 
machine, the pouches are advanced first through a filling station where 
product is introduced into the pouches. The pouches next are advanced to a 
steaming station where steam is introduced into the pouches to drive the 
air out of the pouches. Thereafter, the pouches are advanced out of the 
steaming station and into a sealing station where the open ends of the 
pouches are sealed. All operations take place while the pouches are in 
ambient atmosphere and thus it is not necessary to provide a retort for 
maintaining an environment of steam. 
SUMMARY OF THE INVENTION 
The general aim of the present invention is to provide a new and improved 
packaging method and also a new and improved packaging machine, preferably 
of the Bartelt-type, in which the pouches are filled with product, flushed 
with steam and then sealed while in ambient atmosphere and yet are 
continuously exposed to steam while being sealed so as to prevent the 
entry of air into the pouches between the time the pouches are flushed and 
sealed. 
A related object is to flush the pouches with steam while the pouches are 
dwelling in a steaming station and then to immediately close and seal the 
pouches while the pouches are still dwelling in the steaming station. In 
this way, the pouches are sealed while in the presence of steam and before 
the steam in the pouches can condense and draw air back into the pouches. 
Thus, very little air is present in the sealed pouches. 
The invention also resides in the novel means which are used to close, 
stretch and seal the pouches in a single station. 
These and other objects and advantages of the invention will become more 
apparent from the following detailed description when taken in conjunction 
with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
As shown in the drawings for purposes of illustration, the invention is 
embodied in a packaging machine for filling and sealing envelope-type 
pouches 10. Such a pouch usually is made from a single or composite sheet 
of flexible material having at least one side which is heat sealable. The 
pouch includes two flexible panels 11 which are sealed or otherwise joined 
together along their side and bottom margins, the upper end of the pouch 
being open until the pouch is filled and sealed. 
In many respects, the packaging machine is similar to those disclosed in 
the aforementioned Bartelt patent and in Johnson et al U.S. Pat. No. 
3,553,934 and thus certain elements of the machine need not be described 
in detail. It will suffice to say that each pouch 10 is adapted to be 
gripped releasably at its side margins by leading and trailing clamps 13 
and 14 which are carried on a chain 15 (FIG. 2a). The latter is adapted to 
be advanced intermittently by a drive mechanism (not shown) and, as the 
chain is advanced along a predetermined path, the pouches are moved into 
and momentarily dwell at a series of horizontally spaced stations where 
packaging operations are performed on the pouches. In the present 
instance, the pouches are advanced in spaced edgewise relation and are 
held with their open ends facing upwardly. 
Herein, the machine includes a first filling station 16 having a dispenser 
spout 17 for depositing a product into each pouch 10 as the latter dwells 
beneath the spout. In one particular packaging operation, the product 
which is discharged through the spout is liquid gravy or sauce. To 
facilitate dispensing of the product into the pouch, the trailing clamp 14 
is adapted to be shifted toward the leading clamp 13 and, when the 
trailing clamp is so shifted, it causes the panels 11 of the pouch to bow 
outwardly and open the upper end portion or mouth of the pouch as shown in 
FIGS. 1, 2a and 4a. In order to effect shifting of the trailing clamp 14, 
the latter is carried on a bellcrank 19 (FIG. 2a) which is pivotally 
mounted at 20 on the chain 15. When the trailing clamp is located in the 
filling station 16, a stationary cam (not shown) engages a roller 21 on 
one arm of the bellcrank 19 and causes the latter to swing 
counterclockwise about the pivot 20 and thereby shift the trailing clamp 
toward the leading clamp 13 and effect opening of the pouch. For a more 
detailed disclosure of a shiftable bag clamp, reference may be had to 
Lense et al U.S. Pat. No. 3,568,402. 
After receiving gravy or sauce at the filling station 16, each pouch 10 is 
advanced to a second filling station 25 where another product is 
introduced into the pouch through a spout 26. The product which is 
dispensed at the second filling station may be a solid product such as 
chunks of meat or vegetables which have been quick frozen to preserve 
their flavor and nutrients. Thus, in the present instance, a cold solid 
product is placed in the pouches at the second filling station. The 
pouches are held open by the trailing bag clamps 14 during dispensing of 
the product at the second filling station. 
Each filled pouch 10 next advances to a steaming station 30 where dry steam 
at approximately 450.degree. F. is introduced into the pouch through a 
nozzle 31 while the upper end of the pouch is still held open by the 
trailing clamp 14. The steam drives air and gases out of the pouches for a 
purpose to be explained subsequently. As shown in FIGS. 1, 2a and 4a, the 
steam nozzle 31 is located just above the upper end of each pouch which 
dwells in the steaming station 30 and is of a flat and elongated shape so 
as to discharge the steam across substantially the entire length of the 
mouth of the pouch. 
After each pouch 10 is flushed with steam, its upper end portion is heat 
sealed and the pouch is advanced to a station 33 for removal from the 
clamps 13 and 14. The pouch is subsequently transferred to an autoclave 
(not shown) which is adapted to heat the pouch to high temperatures in 
order to sterilize the contents of the pouch. Any air which is in the 
pouch will expand when subjected to the heat of the autoclave and, if any 
significant amount of air is present in the pouch, it will cause the pouch 
to balloon and may cause either the panels 11 or the seals to break. Also, 
the presence of oxygen in the pouch is detrimental to the shelf life of 
some products. Accordingly, it is important to remove air from the pouch 
and, in the present instance, this is achieved by introducing steam into 
the pouch at the steaming station 30. The steam drives most of the air out 
of the pouch and, upon condensing, creates a vacuum in the sealed pouch. 
According to the present invention, more effective use is made of the steam 
by closing and sealing each pouch 10 while the pouch is still in the 
steaming station 30 and preferably while steam is still being directed 
downwardly toward the pouch. By sealing the pouch in the steaming station 
and in the presence of steam rather than advancing the pouch to a 
downstream station for sealing, more live steam is captivated in the pouch 
and there is less danger of the steam condensing and drawing air back into 
the pouch before the latter is sealed. As a result, the pouch contains 
less air when the pouch is sealed at the steaming station itself in 
accordance with the principles of the present invention. 
In carrying out the invention, the upper end portion of each pouch 10 is 
first closed, is then stretched and is then heat sealed. These operations 
all occur while the pouch is dwelling at the steaming station 30 beneath 
the steam nozzle 31, the steam preferably being discharged continuously 
from the nozzle and not being interrupted at any time either when the 
pouch is dwelling or is being advanced. Closing of the pouch is effected 
shortly after the pouch has initially stopped in the steaming station and 
has received a charge of steam. To this end, a swingable bar 35 (FIG. 2a) 
is located adjacent the upstream end of the steaming station. When each 
pouch first enters the station, the bar is positioned as shown in FIG. 2a 
and engages the roller 21 of the trailing bag clamp 14 to keep that clamp 
shifted toward the leading clamp 13 and thus hold the pouch open. After 
the pouch has stopped in the steaming station for a short interval and has 
been flushed with steam, the bar 35 is swung counterclockwise to the 
position shown in FIG. 2b. As an incident to such swinging, a coil spring 
36 forces the bellcrank 19 to turn clockwise about the pivot 20, the 
spring being compressed between the bellcrank and the trailing clamp 14. 
Clockwise turning of the bellcrank shifts the trailing clamp away from the 
leading clamp 13 so that the panels 11 of the pouch are drawn toward one 
another to close the upper end portion of the pouch. When the pouch is 
closed, the upper margins of the panels are disposed in substantially 
face-to-face relation as shown in FIG. 2b. 
While shifting of the trailing clamp 14 away from the leading clamp 13 is 
effective to close the upper end of the pouch 10, the upper margins of the 
side panels 11 are not drawn into perfectly flat face-to-face relationship 
and, in addition, such upper margins may be somewhat wrinkled or wilted as 
a result of the steam impinging on the flexible material. Accordingly, the 
upper margins of the panels are stretched preparatory to being heat 
sealed. For this purpose, the machine includes four stretcher shoes 40a, 
40b, and 40c, 40d adapted to engage the opposite sides of the panels 11 
adjacent their top and side margins and operable to stretch and flatten 
the upper portion of the pouch. As shown in FIGS. 3 and 4b, each shoe is 
in the form of a small rubber pad which is attached to a generally 
L-shaped mounting element 41. The shoes 40a and 40b are located on one 
side of the pouch 10 and are positioned adjacent opposite side margins of 
the pouch and just above the clamps 13 and 14. The shoes 40c and 40d are 
located on the opposite side of the pouch and directly oppose the shoes 
40a and 40b, respectively. 
The mounting element 41 for each stretcher shoe 40 is connected to a 
support bar 43 by a pair of pivoted, parallel links 44, the mounting 
elements for the shoes 40a and 40b being connected to a support bar on one 
side of the pouch and the mounting element for the shoes 40c and 40d being 
connected to a support bar on the other side of the pouch. Each support 
bar, in turn, is clamped to a pair of upright rods 45 which are adapted to 
be swung toward and away from the pouch by conventional mechanism such as 
shown in FIG. 21 of the aforementioned Johnson et al patent. 
When the pouch 10 is being advanced into the steaming station 30 and until 
after closing of the pouch by the trailing clamp 14, the rods 45 are in 
retracted positions as shown in FIGS. 2a and 4a. With the rods in this 
position, the stretcher shoes 40 are retracted away from one another and 
the pouch so as to allow the open pouch to move into and occupy the 
steaming station. When the shoes are in their retracted positions, 
contractile springs 48 (FIG. 2a) urge the shoe 40a toward the shoe 40b and 
urge the shoe 40c toward the shoe 40d, there being one spring connected 
between the mounting elements 41 for the shoes 40a and 40b and another 
spring connected between the mounting elements for the shoes 40c and 40d. 
Stop screws 50 on the mounting elements engage the ends of the support 
bars 43 to limit the extent to which the springs may pull the shoes toward 
one another. 
Immediately after the pouch 10 is closed by the trailing clamp 14, the rods 
45 are swung toward one another as shown in FIGS. 2c and 4b. As an 
incident thereto, the shoes 40a and 40c engage and press against one side 
margin of the pouch while the shoes 40b and 40d engage and press against 
the other side margin. As a result of the force created by the shoes 40a 
and 40c and the shoes 40b and 40d pressing against one another, the links 
44 pivot and cause the shoes 40a and 40c to shift rearwardly and the shoes 
40b and 40d to shift forwardly. With the upper margin of the pouch clamped 
between the opposing shoes, such shifting causes the upper margin to be 
stretched into a substantially flat and wrinkle-free condition as shown in 
FIGS. 3 and 4c. 
In keeping with the invention, the upper margin of the pouch 10 is heat 
sealed just after being stretched and while steam is still being directed 
downwardly toward the pouch in the steaming station 30. To seal the pouch, 
a pair of opposed sealing bars 53 (FIG. 4a) are carried on the rods 45 
just below the support bars 43 and are disposed on opposite sides of the 
pouch. The sealing bars are equipped with heating elements 54 and are 
formed with narrow sealing shoes 55 located just below the stretcher shoes 
40 and having a width corresponding to the width of the pouch. When the 
stretcher shoes 40 first engage the pouch, the sealing shoes 55 are spaced 
slightly from the pouch as shown in FIG. 4b. But, as the links 44 pivot 
and the stretcher shoes move forwardly and rearwardly to stretch the 
pouch--and with continued inward swinging of the rods 45--the sealing 
shoes 55 engage opposite sides of the pouch as shown in FIG. 4c and form a 
heat seal extending along the upper end portion of the pouch across the 
full width thereof. The rods 45 then are swung outwardly to retract the 
stretcher shoes 40 and the sealing shoes 55 away from the pouch so that 
the latter may be advanced out of the steaming station 30. 
The seal effected by the sealing shoes 55 is made at comparatively high 
speed and may not be sufficiently reliable to serve as the final top seal 
for the pouch 10. This seal does, however, intimately join the upper 
margins of the side panels 11 and prevents steam from escaping out of and 
air from entering into the pouch. Importantly, this seal is made while 
steam is still being directed toward the pouch. Thus, the seal is effected 
before the steam in the pouch can condense and create a vacuum to draw air 
into the pouch as would occur if the pouch were advanced out of the 
steaming station in an unsealed condition. Formation of the seal in the 
steaming station is even more important where--as here--some of the 
product in the pouch is very cold. The cold product tends to accelerate 
condensation of the steam and, when the pouch is not sealed in the 
steaming station itself, the vacuum resulting from such condensation can 
draw air back into the pouch before the pouch can be sealed at a 
downstream station. Accordingly, the present invention results in the 
presence of less air in the pouch since the seal is established after 
steam is introduced into the pouch and before there is any significant 
condensation of the steam. 
After being advanced out of the steaming station 30, the pouch 10 is 
shifted into a final sealing station 60 (FIG. 1) before being transferred 
to the discharge station 33 and the autoclave. When the pouch dwells at 
the final sealing station 60, a good quality top seal is formed by a 
conventional impulse sealer comprising a sealing bar 61 and a backing bar 
63, both bars being carried on swingable rods 64 similar to the rods 45. 
The impulse seal which is thus formed improves the integrity of the seal 
made at the steaming station 30 and keeps the pouch tightly sealed until 
such time as the pouch is opened for removal of the product. 
From the foregoing, it will be apparent that the present invention effects 
closing and sealing of the pouch 10 while the latter is in the steaming 
station 30 and thus the sealed pouch contains only a relatively small 
amount of air. While the invention has been specifically disclosed in 
connection with a packaging machine in which the pouches are advanced 
intermittently, those familiar with the art will appreciate that the 
principles of the invention could be applied to a continuous motion 
machine. Also, it should be appreciated that the present invention 
achieves effective steaming of the pouches and yet enables filling and 
sealing of the pouches while the pouches are being advanced through the 
ambient atmosphere. Accordingly, it is not necessary to place the pouches 
in either a steam or vacuum retort to remove the air.