Packaging machine with continuous motion top sealer

Sealing heads for heat sealing the tops of continouously movable upright pouches are spaced angularly around a continuously rotatable turret and seal the pouches after steam has been introduced into the pouches and as the pouches move in an arcuate path extending around the turret. Each sealing head includes a pair of heated sealing bars and further includes a cam-operated actuator which sequentially lowers the bars, closes the bars, opens the bars, and then raises the bars as the bars rotate with the turret.

BACKGROUND OF THE INVENTION 
This invention relates to a mechanism for use with a packaging machine for 
sealing the tops of flexible pouches as the pouches are advanced at high 
speed and with continuous motion along a predetermined path. Such a 
sealing mechanism includes a plurality of sealing heads which track the 
moving pouches, each of the heads having a pair of heated bars which seal 
the pouch. 
A packaging machine with a continuous motion top sealing mechanism is 
disclosed in Nutting et al U.S. Pat. No. 3,230,687. That sealing 
mechanism, however, is complex and expensive and requires a considerable 
amount of floor space in the lengthwise direction of the machine. In 
addition, each of the sealing heads of the Nutting et al mechanism has 
sealing bars which move in separate orbital paths and thus it is difficult 
to maintain precise control over the bars and particularly with respect to 
the sealing pressure which is exerted by the bars. 
The invention has more particular reference to a top sealing mechanism for 
a packaging machine in which steam is introduced into the pouches just 
prior to the time the pouches are sealed. A packaging machine in which the 
pouches are flushed with steam is disclosed in Johnson U.S. Pat. No. 
4,081,942. The Johnson machine, however, operates with intermittent motion 
rather than with continuous motion and thus the pouches dwell while their 
tops are being sealed. 
SUMMARY OF THE INVENTION 
The general aim of the present invention is to provide a new and improved 
continuous motion top sealing mechanism which is of relatively simple and 
compact construction and which is capable of forming good seals at high 
speeds even when steam is present in the pouches during the sealing 
operation. 
A further object of the invention is to provide a continuous motion sealing 
mechanism in which the bars of each sealing head are paired with one 
another in such a manner that the bars of each head move in a common path 
so as to simplify the mechanism and to enable more positive control of the 
sealing pressure exerted by the bars. 
A more detailed object is to provide a sealing mechanism in which the 
sealing heads are mounted on a continuously rotatable turret and track the 
pouches as the latter move in an arcuate path around the turret. 
Still another object of the invention is to provide a unique sealing head 
in which a single actuator is effective first to lower the sealing bars of 
the head into straddling relation with the top of a pouch and then to 
close the bars to seal the pouch. 
The invention also resides in the novel construction which permits 
condensate to be driven out of the seal area of each pouch as the sealing 
bars are closed and which permits substantially uniform sealing pressure 
to be exerted on the pouch after the bars have been closed. 
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 mechanism 20 which forms part of a continuous motion 
packaging machine and which serves to close and seal the tops of pouches 
21 (FIG. 2) after the latter have been filled by the machine. Each pouch 
comprises a pair of opposed side panels made of flexible thermoplastic 
material and joined along their sides and bottoms by heat seals. In this 
particular instance, the pouches are filled with a food product such as, 
for example, a mixture of meat chunks and sauce. 
Each filled pouch 21 is held in an upright position by a pair of clamps 22 
(FIGS. 2 and 14) which grip the edge margins of the pouch near the top 
thereof. Each pair of clamps forms part of a carrier 24 which is attached 
to two vertically spaced chains 25 adapted to be advanced from 
left-to-right (FIG. 1) with high speed continuous motion and adapted to be 
guided by sprockets 26 and 27 during such advance. The two clamps of each 
carrier are adapted to be moved toward one another to cause the pouch to 
open widely prior to and during filling (see the three leftmost pouches in 
FIG. 1) and then are adapted to be moved away from one another to close 
the pouch and stretch the top thereof before the top is sealed. Clamps 
which move toward and away from one another to open and close pouches are 
disclosed in Lense et al U.S. Pat. No. 3,568,402. Also, the specific 
carriers 24 of the present machine are disclosed in Russell et al United 
States application Ser. No. 119,221 filed Feb. 7, 1980, now U.S. Pat. No. 
4,263,768, entitled Pouch Carrier and assigned to the assignee of the 
present invention. The details of the carriers do not form part of the 
present invention and thus further description of the carriers is not 
necessary to enable an understanding to be gained of the sealing mechanism 
20. 
As the chains 25 advance from the sprockets 26 to the sprockets 27, they 
engage and rotate a pair of vertically spaced sprockets 28 (FIG. 2) which 
form part of a turret 30 supported on a stationary base 31. The turret 
includes a vertical column 32 which is secured to the sprockets and which 
thus is rotated in a counterclockwise direction and in timed relationship 
with the advance of the chains and the pouches 21. The chains and the 
pouches move in an arcuate path which extends around approximately the 
forward 180 degrees of the sprockets 28 or from approximately a nine 
o'clock position to approximately a three o'clock position as viewed in 
FIG. 1. 
Fixed to the upper end of the column 32 is a circular manifold 34 (FIGS. 1 
and 2) which receives steam from a suitable source via a rotary coupling 
35 located at the center of the manifold. A plurality (herein, three) of 
angularly spaced pipes 36 deliver steam from the coupling to a chamber 
within the manifold while a similar number of lower pipes 37 return 
condensate from the chamber. 
Steam is introduced into each filled pouch 21 just before the latter is 
sealed in order to purge the pouch of air and to subsequently create a 
vacuum in the pouch to preserve the food product. To introduce the steam 
into the pouches, eighteen nozzles 38 (FIG. 2) communicate with and depend 
from the manifold 34 and extend downwardly through holes formed in a 
circular plate 40 which underlies the manifold and which is secured to the 
column 32 so as to form part of the turret 30. The upper end of each 
nozzle normally is closed by a flapper valve 41. 
As each pouch 21 reaches the nine o'clock position (FIG. 1) and starts to 
travel in an arcuate path around the sprockets 28, the pouch moves into 
registry with one of the nozzles 38. As the turret 30 rotates, the pouch 
and the alined nozzle move in unison with the pouch being held in an open 
position by the clamps 22. During such movement, the flapper valve 41 at 
the upper end of the nozzle is opened by mechanism indicated generally at 
42 in FIG. 2. The valve 41 is held open for a short period of time (e.g., 
fifteen degrees movement of the turret 30) in order to introduce steam 
into the pouch. While steam is still being ejected from the nozzle, the 
clamps 22 are moved away from one another to stretch the top of the pouch 
to a closed position and restrict the escape of steam out of and the entry 
of air into the pouch. 
In accordance with the present invention, the turret 30 forms part of the 
top sealing mechanism 20 and carries a plurality of unique angularly 
spaced sealing heads 45 which seal the tops of the pouches 21 as the 
latter move in an acruate path extending around the turret. The sealing 
heads are relatively simple, are comparatively easy to control and form 
good seals at high speeds even though the pouches are subjected to steam 
immediately prior to sealing. By spacing the sealing heads 45 around the 
turret, the amount of floor space which the sealing mechanism 20 requires 
in the lengthwise direction of the packaging machine is significantly 
reduced. 
More specifically, eighteen sealing heads 45 are spaced equally around the 
turret 30 and each is carried on and mounted beneath the plate 40. The 
angular spacing between the sealing heads is equal to the spacing between 
the pouches 21 and, in addition, the sealing heads are positioned radially 
so as to register with the pouches as the latter move in an arcuate path 
extending around the forward half of the turret. Thus, successive sealing 
heads move into overlying relation with successive pouches as the pouches 
reach a nine o'clock position (FIG. 1) and begin to travel in an arcuate 
path. Each sealing head moves in unison with and tracks its respective 
pouch as the pouch continues around the arcuate path and then leaves the 
pouch when the latter reaches a three o'clock position and proceeds toward 
the sprockets 27. 
The sealing heads 45 are identical to each other and thus only a single 
head need be described. As shown in FIGS. 3 and 8, each sealing head 
includes a main body 46 located beneath the plate 40 and extending in a 
radical direction relative to the turret 30. Ears 47 project laterally 
from one side of the body and are interleaved with spaced ears 48 (FIG. 3) 
which form part of a depending bracket 49 secured to the plate 40. A 
horizontal pin 50 extends through the ears 48 and 49 and mounts the body 
46 for up and down swinging relative to the bracket 49. 
The side of the body 46 opposite the ears 47 carries a sealing bar 51 (FIG. 
8). The latter comprises a radially extending elastomeric pad 52 which is 
bonded to a metal plate 53 which, in turn, is secured rigidly to the body 
by screws 54. A Teflon jacket 55 covers the pad 52 and is adapted to 
engage the upper end portion of one of the side panels of the pouch 21. 
The bar 51 is adapted to be heated by an electrical resistance heating 
element 56 embedded in the body 46 and connected by an electrical cable 57 
(FIG. 3) to a slip ring assembly (not shown) located at the center of the 
turret 30 and connected to a suitable voltage source. 
A second sealing bar 58 (FIGS. 12 and 15) coacts with the bar 51 to seal 
the pouch 21 and is carried on a radially extending mounting member or 
shoe 60 (FIGS. 8 and 15). Laterally projecting ears 61 (FIG. 3) are formed 
on the ends of the mounting shoe and are alined with a pair of ears 62 
formed on the body 46. Pins 64 project through the ears 61 and 62 and 
mount the shoe 60 for upward and downward swinging on the body 46 about a 
horizontal axis extending parallel to the pin 50. 
As shown in FIG. 15, the sealing bar 58 comprises a metal block 65 which is 
covered with a Teflon jacket 66. Mounting brackets 67 (FIGS. 14 to 16) are 
secured to the ends of the shoe 60 by screws 68 and each is formed with a 
downwardly opening socket 70 (FIG. 16) which rotatably receives a 
horizontal trunnion 71 (FIG. 15) projecting from the end of the block 65. 
A generally I-shaped retainer 72 projects from each end of the block 65 
and interfits with a half-round rod 73 projecting from the adjacent 
mounting bracket 67. The retainers 72 and the rods 73 coact to hold the 
trunnions 71 upwardly within the sockets 70 while permitting the trunnions 
to turn within the sockets. In this way, the sealing bar 58 is capable of 
swinging or pivoting relative to the mounting shoe 60 and the brackets 67 
about the axes of the trunnions 71. The retainers 72 engage the rods 73 to 
limit swinging of the bar 58 in a clockwise direction (FIG. 15). 
The sealing bar 58 is urged toward the bar 51 by an elastomeric rod 74 
(FIGS. 12 and 15) which is located between the mounting shoe 60 and one 
face of the bar 58. The rod 74 is substantially co-extensive in length 
with the bar 58 and is captivated within a groove 75 formed in the 
mounting shoe. 
To heat the bar 58, an electrical resistance heating element 76 (FIG. 8) is 
embedded in the mounting shoe 60 and is adapted to be energized via an 
electrical cable 77 (FIG. 3). The cable is connected to the slip ring 
assembly at the center of the turret 30. 
In keeping with the invention, each sealing head 45 is equipped with a 
reversible actuator 80 (FIG. 3) which is uniquely arranged so as to first 
lower the sealing bars 51 and 58 of the head into straddling relation with 
the top of a pouch 21 and then to close the bars to seal the pouch. 
Thereafter, the actuator opens the bars and then raises the bars. Herein, 
the actuator includes a cam follower element in the form of a roller 81 
located at the outer end of the sealing head 45 and positioned to ride in 
a cam track 82 (FIGS. 2 and 8). The cam track is defined by a groove 
formed in a stationary ring 83 (FIG. 2) which encircles the turret 30 and 
which is supported by posts 84 upstanding from the base 31. 
As shown in FIGS. 3 and 4, the cam follower 81 is connected to the free end 
of an arm 85 whose other end is pinned rigidly at 86 to the outer end of a 
horizontal shaft 87. The shaft 87 is received within the main body 46 of 
the sealing head 45 and is rotatably supported within bushings 88 (FIG. 3) 
carried by the body. 
Pinned rigidly at 90 (FIG. 8) to the inner end portion of the shaft 87 is a 
U-shaped bracket 91 which rotatably supports a part in the form of a 
roller 92 adapted to rotate about a horizontal axis 94. When the sealing 
bars 51 and 58 are in their raised positions as shown in FIG. 8, the 
roller 92 engages a flat surface 95 of the body 46 and also engages a leaf 
spring 96 which is carried by the mounting shoe 60 and which extends 
lengthwise of the shoe a short distance beyond the sides of the roller 92. 
The leaf spring is captivated within a groove 97 in the shoe and, in this 
instance, is bowed upwardly about its longitudinal centerline as shown in 
FIG. 8. The spring could, however, be bowed upwardly about its transverse 
centerline. 
OPERATION 
To best gain an understanding of the operation of the sealing mechanism 20, 
assume that a given sealing head 45 is traveling counterclockwise with the 
turret 30 and is located in approximately a twelve o'clock position (FIG. 
1). When the sealing head is so positioned, the cam track 82 holds the cam 
follower 81 in an extreme upper position so that the cam follower, the arm 
85 and the shaft 87 are located as shown in FIG. 4. With the shaft 87 in 
the position shown in FIG. 4, the roller 82 bears against the surface 95 
of the body 46 and holds the body and the sealing bar 51 in an upwardly 
raised position shown in FIGS. 4, 5 and 8, the roller preventing the body 
from pivoting downwardly about the pin 50. Because the body 46 is in a 
raised position, the pins 64 are held in an elevated position and keep the 
mounting shoe 60 and the sealing bar 58 raised upwardly (see FIGS. 4, 5 
and 8). In addition, a pin 98 (FIGS. 4 and 5) projecting inwardly from the 
arm 85 engages the lower side of a pin 99 projecting outwardly from the 
mounting shoe 60. Such engagement prevents the shoe 60 from swinging 
downwardly (or clockwise as viewed in FIG. 5) about the pins 64 and thus 
prevents the bar 58 from closing on the bar 51. 
Accordingly, the coaction between the cam follower 81 and the cam track 82 
holds the sealing bars 51 and 58 in raised positions disposed above the 
level of the pouches 21. Also, the pins 98 and 99 serve to keep the 
sealing bar 58 in an open position with respect to the sealing bar 51. 
As each sealing head 45 rotates to the nine o'clock position (FIG. 1), the 
sealing bars 51 and 58 move into alinement with the top of a pouch 21 
being advanced by the chains 25 but the bars are located above the pouch 
as shown in FIGS. 4, 5 and 8. While the bars are in this position and as 
the pouch continues to advance, the flapper 41 (FIG. 2) is opened to admit 
steam into the pouch through the nozzle 38. Shortly before the flapper 41 
is closed, the pouch is stretched by the clamps 22 to close the top of the 
pouch. 
At about the same time, the cam track 82 causes the follower 81 to lower 
and effect counterclockwise (FIG. 4) swinging of the arm 85 and 
counterclockwise turning of the shaft 87. As an incident thereto, the 
roller 81 swings about the axis of the shaft 87 and permits the body 46 of 
the sealing head 45 to swing downwardly under its own weight about the pin 
50 from the position shown in FIGS. 4, 5 and 8 to the position shown in 
FIGS. 6 and 9. Such swinging lowers the seal bar 51 to a position directly 
alongside the trailing side of the top of the pouch. The pins 64 and the 
mounting shoe 60 swing downwardly in unison with the body 46 and thus the 
seal bar 58 is lowered to a position in which the bar 58 is located in 
opposing relationship with the leading side of the top of the pouch 21. As 
the body 46, the shoe 60 and the arm 85 swing downwardly about the pin 50, 
the pins 98 and 99 also swing downwardly in unison and thus the pin 98 
remains in underlying relation with the pin 99 to keep the shoe 60 from 
swinging clockwise about the pins 64. This keeps the sealing bar 58 spaced 
from or open with respect to the bar 51 and allows the two bars to swing 
downwardly into straddling relation with the pouch 21 (see FIGS. 6 and 9). 
The body 46 of the sealing head 45 swings downwardly about the pin 50 until 
a lug 100 (FIGS. 8 and 9) on the body engages and is stopped by the inner 
end of the pin 50 of the adjacent trailing sealing head 46. Such 
engagement stops further downward swinging of the body 46 and holds the 
sealing bar 51 at a fixed elevation in contact with the trailing side of 
the pouch (see FIGS. 6 and 9). The cam track 82, however, continues to 
lower the follower 81 and thus continues to swing the arm 85 
counterclockwise and to turn the shaft 87 counterclockwise. As the arm 
swings, the pin 98 moves downwardly away from the pin 99 to permit the 
mounting shoe 60 and the sealing bar 58 to swing clockwise about the pins 
64 and relative to the body 46 and the sealing bar 51. At the same time, 
counterclockwise turning of the shaft 87 causes the roller 92 to swing 
angularly from the position shown in FIG. 9 to the position shown in FIG. 
10. The roller thus acts against and through the leaf spring 96 and 
positively turns the shoe 60 clockwise about the pins 64 to force the seal 
bar 58 against the leading side of the pouch 21 as shown in FIG. 10. 
Accordingly, the seal bar 58 is moved to a closed position with respect to 
the bar 51 and, as a result, the top of the pouch becomes sandwiched 
between the two bars. 
The cam track 82 causes the seal bars 51 and 58 to be located in the 
positions shown in FIGS. 10 and 12 during the time the sealing head 45 is 
moving through the angular distance labeled "Initial Heat And Seal" in 
FIG. 1. During this time, the seal bars form an essentially line-type seal 
105 (FIG. 12) across the upper end portion of the pouch below the extreme 
top fins 106 thereof in order to hold the steam in the pouch and to 
prevent air from entering the pouch. The fins 106 of the pouch above the 
line seal 105 are not, however, immediately pressed and sealed together 
but instead are left open and are subjected to the heat from the bars 51 
and 58. As a result, moisture which may have accumulated between the fins 
106 because of condensation of the steam is vaporized by the heat and is 
driven upwardly from between the fins. This leaves the fins in a dry 
condition so that the fins may be subsequently sealed together in a 
cosmetically attractive manner and without the formation of blisters which 
otherwise would occur if water droplets were present between the fins at 
the time of sealing. 
The foregoing is achieved in part by virtue of the shape of the seal bars 
51 and 58 and in part by virtue of the mounting of the seal bar 58. As 
shown in FIG. 12, the active face of the pad 52 of the seal bar 51 is not 
disposed in a vertical plane but instead is inclined upwardly and 
rearwardly. The active face of the block 65 of the seal bar 58 is 
substantially V-shaped and thus the apex of the V defines a pronounced 
line 107 (FIG. 15) across the block 65 adjacent the lower end portion 
thereof. When the seal bar 58 is first closed upon the seal bar 51, the 
elastomeric rod 74 biases the seal bar 58 clockwise about the axis of the 
trunnions 71 (FIG. 12) and causes the line 107 along the block 65 to 
engage the pouch and form the line-type seal 105. The upper end portion of 
the block 65, however, does not press the fins 106 against the inclined 
face of the pad 52 and thus the fins remain separated so that the heat 
from the bars can drive off moisture from between the fins. In this way, 
the pouch is initially sealed at 105 to hold the steam in the pouch but 
the fins 106 are dried so that the fins subsequently can be sealed 
together with a neatly appearing cosmetic seal. 
Cosmetic sealing of each pouch 21 is effected during the time the pouch and 
the associated sealing head 45 are being advanced through the angular 
distance or range labeled "Final Seal" in FIG. 1. When the sealing head 
first enters this range, the cam track 82 lowers the follower 81 even 
further to cause the arm 85 to rotate the shaft 87 further in a 
counterclockwise direction from the position shown in FIG. 10 to the 
position shown in FIG. 11. As a result, the roller 92 turns about the axis 
of the shaft 87 and forces the mounting shoe 60 to swing clockwise about 
the axis of the pins 64. The mounting shoe thus is swung to a fully 
clamped position shown in FIGS. 7, 11 and 13 and, as the shoe reaches this 
position, the sealing bar 58 presses against the pouch 21 and the sealing 
bar 51 and rocks counterclockwise about the axes of the trunnions 71. Such 
rocking, together with the swinging of the shoe 60 about the axis of the 
pins 64, brings virtually the full face of the bar 58 into contact with 
the upper end portion of the pouch 21 so that the fins 106 thereof are 
fully pressed between and sealed by the bars 51 and 58 in order to effect 
a neatly appearing seal across the top of the pouch. Such swinging also 
causes compression of the elastomeric pad 52 of the seal bar 51 and of the 
elastomeric rod 74 located behind the bar 58 (see FIG. 13). As a result, 
the pad and the rod exert a biasing force on the shoe 60 and tend to swing 
the shoe counterclockwise about the axis of the pins 64. 
Counterclockwise swinging of the shoe 60 is prevented, however, by the 
roller 92 and the leaf spring 96. As illustrated in the drawings, the axis 
94 of the roller 92 swings past or toggles over the line extending between 
the pins 64 and the shaft 87 when the roller is moved from the position 
shown in FIG. 10 to the position shown in FIG. 11. As the roller moves to 
the position shown in FIG. 11, it deflects the leaf spring 96. Such 
deflection along with the deflection of the elastomeric rod 74 enables the 
seal bar 58 to exert a controlled and substantially uniform clamping 
pressure on the pouch 21. Because of the overcenter toggle action 
undertaken by the roller 92, the roller exerts a substantially uniform 
holding force on the shoe 60 and such force remains virtually constant 
regardless of minor variations which might be present in the cam track 82. 
In other words, the roller 92, having toggled overcenter, will tend to 
remain in the position shown in FIG. 11 even if minor variations in the 
cam track 82 result in slight upward or downward movement of the cam 
follower 81. Accordingly, substantially constant sealing pressure is 
exerted on the pouch 21 during the time the final or cosmetic seal is 
being formed. 
When each sealing head 45 passes approximately the four o'clock position 
shown in FIG. 1, the cam track 82 raises the follower 81 so as to effect 
clockwise swinging of the arm 85 and clockwise turning of the shaft 87. 
After the arm has been swung through a short distance, the pin 98 on the 
arm picks up and engages the pin 99 on the mounting shoe 60. This causes 
the mounting shoe to swing counterclockwise about the pins 64 to the 
position shown in FIG. 9 and release the sealing bar 58 from the pouch 21. 
With further counterclockwise turning of the turret 30 and the sealing 
head 45, the cam track 82 raises the follower 81 by an additional distance 
to cause the shaft 87 to turn clockwise from the position shown in FIG. 9 
to the position shown in FIG. 8. Accordingly, the roller 92 engages the 
surface 95 of the body 46 and swings the body clockwise about the pin 50 
to raise the sealing bar 51 above the pouch and to its upper position 
shown in FIG. 8. The sealing bar 58 is raised in unison with the bar 51 
because the engagement between the pins 98 and 99 prevents the mounting 
shoe 60 from swinging about the pins 64 and forces the shoe to move 
upwardly with the body 46. 
Raising of the bars 51 and 58 above the pouch 21 is effected prior to the 
time the sealing head 45 and the pouch reach the three o'clock position 
(FIG. 1). Once this position has been reached, the pouch is advanced away 
from the turret 30 by the chains 25 while the sealing head is advanced 
around the rear side of the turret preparatory to picking up another 
pouch. 
Thus, the present invention brings to the art a unique continuous motion 
top sealing mechanism 20 in which the sealing heads 45 are spaced 
angularly around a turret 30 and in which the sealing bars 51 and 58 of 
each head are paired with one another so that both bars move in a common 
path. As a result of mounting the sealing heads on the turret, the sealing 
mechanism takes up comparatively little floor space in the lengthwise 
direction of the packaging machine. Because the sealing bars of each head 
move in a common path, the bars and the pressure exerted thereby can be 
precisely controlled in a relatively simple manner. Indeed, the single 
acutator 80 is effective to lower, close, open and then raise the bars and 
to cause the bars to exert substantially uniform pressure on the pouch. 
The specific construction of the bars and the manner of closing the bar 58 
allows the formation of hermetically tight and cosmetically acceptable 
seals even when steam is present in the pouch during the sealing 
operation.