Container seaming apparatus and methods

A container seaming machine has a first drive for positioning a seaming roller with respect to a circumferential edge of the lid, and a second drive for rotating the seaming roller with respect to a container lid chuck, container body and container lid. The first drive and the second drive are independently controllable from each other, and each drive is controlled and coordinated by a programmable controller to seam the lid to the container body. Another drive, also controlled by the programmable controller, lifts the container body toward the chuck and allows for varying degrees of force to be exerted between the container body and the lid. The drives use servomotors and linear actuators for precise positioning control. A process for displacing air from containers prior to seaming a lid to a container is also provided. In the process, a container body is filled with contents and is then injected with liquid nitrogen. A lid is immediately placed on the container body, and a biasing force is immediately applied against the lid to maintain the lid on the liquid nitrogen filled container bodies until the container body reaches the seaming mechanism. The biasing force is sufficient to allow a portion of nitrogen gas from vaporization of the liquid nitrogen to escape from the container body, and to allow air originally present in the container body to escape from the container body, while preventing surrounding air from entering the container body.

BACKGROUND OF THE INVENTION 
The present invention relates generally to seaming machines. A seaming 
machine is used to seam a lid to a contents-filled container body so as to 
form a sealed container. The seaming machine typically has two seaming 
rollers associated with the seaming machine to form a sanitary seam, also 
called a double seam, between the container body and the lid. 
Conventional seaming rollers are positioned by mechanical cams controlled 
by mechanical drives, gear trains and the like, all of which are carefully 
coordinated and interlinked with a drive that rotates the container body 
with respect to the seaming rollers. Due to the complex linkages uses in 
conventional seaming machines and reliance on primarily mechanical drives, 
it is very time-consuming to make adjustments to a seaming machine when 
the machine becomes out of tolerance, or if a different size container is 
used. For example, it may take as long as an entire workday, as well as 
the swapping of parts, to change a machine if a different container size 
is used. The changeover results in lost production time and requires 
skilled, hard to find,, machine operators. A conventional seaming machine, 
by virtue of its inherent design, is also limited in the range of 
different container sizes that it can be adjusted to handle. 
When packaging goods which spoil due to exposure to air, the air is removed 
from the container before the lid is sealed thereon. One process for 
removing the air and which avoids the necessity to seam under a vacuum, is 
to inject liquid nitrogen into the container before the lid is seamed onto 
the container. As the liquid nitrogen vaporizes, the resultant nitrogen 
gas drives out the air. This process requires precise timing to ensure 
that substantially all of the liquid nitrogen vaporizes and that no air 
leaks back into the container before the lid is seamed on. It is very 
difficult to achieve the precise timing. 
Accordingly, there is a need for seaming machines and processes which 
overcome the problems discussed above. 
BRIEF SUMMARY OF THE INVENTION 
A container seaming machine is provided which includes a seaming chuck, a 
seaming roller and a first and a second drive. The seaming chuck holds a 
lid firmly against an end of a container body during a seaming operation. 
The first drive is connected to the seaming roller and positions the 
seaming roller with respect to a circumferential edge of the lid. The 
second drive causes rotation of the seaming chuck, thereby causing 
rotation of the container body and container lid. The first drive and the 
second drive are independently controllable from each other. A 
programmable controller provides the separate control and coordination of 
the two drives. A method of seaming a lid to a container body by using the 
container seaming machine is also provided. The first drive may include a 
servomotor and a linear actuator. The servomotor receives control data 
related to the desired position of the seaming roller with respect to the 
circumferential edge of the container body, and the container lid. The 
linear actuator translates a servomotor output to cause movement of the 
seaming roller. 
Another embodiment of the invention provides a container seaming machine 
for performing a seaming operation on a container body and lid by using a 
seaming roller. The machine includes a seaming chuck, a base surface, a 
drive and a pressure sensor. The seaming chuck holds the lid firmly 
against an end of the container body during a seaming operation. The other 
end of the container body is placed on the base surface. The drive causes 
the base surface to move toward the seaming chuck so that the end of the 
container body and the lid are held firmly against the seaming chuck and 
so that the container body and lid are in position for performing the 
seaming operation. The end of the container body and the lid exert a force 
against each other which is determined by the final position of the drive. 
In this manner, the final position of the drive is adjustable so that the 
drive may cause varying degrees of force to be exerted between the 
container body and the lid. The pressure sensor is associated with an 
output of the drive. The pressure sensor measures the force exerted 
between the container body and the lid. The measured force is used to 
determine the final position of the drive. 
Another embodiment of the invention provides a process to displace air from 
containers prior to seaming a lid to a container. In the process, a 
container body is filled with contents and is then injected with liquid 
nitrogen. A lid is immediately placed on the container body, and a biasing 
force is immediately applied against the lid to maintain the lid on the 
liquid nitrogen filled container bodies until the container body reaches 
the seaming mechanism. The biasing force is sufficient to allow a portion 
of nitrogen gas from vaporization of the liquid nitrogen to escape from 
the container body, and to allow air originally present in the container 
body to escape from the container body, while preventing surrounding air 
from entering the container body. The biasing force is applied for a 
period of time which is sufficient to allow substantially all of the 
liquid nitrogen to vaporize, and thereby displace substantially all of the 
air originally present in the container body. The biasing force may be 
applied by a spring loaded rail. An apparatus for performing this process 
is also provided.

DETAILED DESCRIPTION OF THE INVENTION 
In the drawings, the same reference numerals are employed for designating 
the same elements throughout the several figures. 
FIG. 1 shows an assembly line 10 for moving content-filled container bodies 
12 through a seaming station 14 which seams lids 16 to the container 
bodies 12 to form lidded, sealed containers 18. The assembly line 10 
includes a conveyor 20 for moving the container bodies 12 and the seamed 
containers 18. The seaming station 14 defines a vacuum chamber 22 having a 
seaming machine 24 therein. The individual components of the seaming 
machine 24 are described in detail below. 
The container seaming machine 24 described herein seams lids to container 
bodies under a vacuum state. To accomplish this task, the assembly line 10 
further includes an inlet or entrance feed valve 26 and a discharge or 
exit feed valve 28, each of which have respective inlets and outlets in 
fluid communication with the seaming station 14. The entrance feed valve 
26 introduces the container bodies 12 to the vacuum chamber 22 of the 
seaming station 14. Vacuum begins to be pulled on the container bodies 12 
as the container bodies 12 pass through the feed valve 26. The exit feed 
valve 28 removes the lidded, sealed containers 18 from the seaming station 
14. 
The region of FIG. 1 labeled as 30 is a vacuum region, the highest vacuum 
occurring in the vacuum chamber 22. Thus, while not illustrated in FIG. 1, 
the outlet of the entrance feed valve 26 and the inlet of the exit feed 
valve 28 are in fluid communication with each other and are sealed from 
the surrounding environment. An integrated seaming mechanism which has an 
entrance feed valve 26, a seaming station 14 under vacuum, and an exit 
feed valve 28 is conventional, and thus is not described in detail herein. 
One example of such a mechanism is a CANCO 117 seaming machine, made by 
Canco, Greenwich, Conn. The feed valves 26 and 28 in such a mechanism use 
turrets to move the container bodies 12 from the valve inlets to the valve 
outlets. The feed valves 26 and 28 may be similar to the feed valves in 
the Canco machine, or they may be similar to feed valves of other types of 
conventional vacuum-operated seaming mechanisms. 
While the disclosed embodiment of the present invention seams under vacuum, 
the vacuum environment is not a necessary feature of the invention, and 
the seaming may occur at atmospheric pressure. Thus, the vacuum chamber 22 
is optional, the feed valve 26 need not necessarily draw a vacuum, and the 
outlet of the feed valve 26 and the inlet of feed valve 28 need not 
necessarily be in fluid communication to maintain a vacuum. A less complex 
feed process may also be used in place of the feed valves 26 and 28 to 
deliver container bodies 12 to, and remove lidded containers 18 from, the 
seaming station 14. 
Seaming machines use seaming heads which have seaming rolls or seaming 
rollers attached thereto for performing the seaming function. In one type 
of seaming machine, a seaming chuck holds a lid firmly against a top end 
of a container body so that the lid is held in contact with the top end of 
the container body. A first mechanical drive positions the two seaming 
rollers with respect to a circumferential edge of the lid. A second drive 
on the seaming machine rotates the seaming roller with respect to the 
chuck, container body and container lid. There is typically one motor 
which has two power takeoffs, one for each of the drives. In one 
conventional configuration, the chuck, container body and lid remain 
stationary, and the second drive rotates the seaming roller around the 
container body and lid. In another conventional configuration, a second 
drive on the seaming machine rotates the chuck, which, in turn, rotates 
the container body and lid. There are typically two seaming rollers on a 
seaming machine used for food products. The two seaming rollers form a 
sanitary seam, called a double seam, between the container body and the 
lid. The first roller begins to roll the lid and the container body, 
forming a first operation roll seam, and the second roller completes the 
seam, forming the second operation roll seam. The resultant seam is 
airtight. 
The seaming machine 24 has two such seaming rollers 32 and 34 linked to 
respective seaming roll shafts 36 and 38. The rollers 32 and 34 are of 
conventional design, and thus not described in detail herein. The shafts 
36 and 38 are described in detail below. While the seaming machine 24 has 
two seaming rollers, the present invention is equally applicable to a 
seaming machine which has only one seaming roller. 
Conventional seaming rollers are positioned by mechanical cams controlled 
by mechanical drives, gear trains and the like, all of which are carefully 
coordinated and interlinked with the second drive that rotates the 
container body with respect to the seaming rollers. To change the settings 
of a conventional seaming machine, such as to accommodate a different 
container diameter or to correct a "seam out-of-tolerance" condition, the 
entire machine must be shut down and a very time-consuming resetting 
procedure must be performed. A changeover to a different container 
diameter may take several hours. Furthermore, conventional seaming 
machines typically require thousands of dollars of change parts to handle 
a different container sizes. 
One important feature of the present invention is that the seaming rollers 
32 and 34 are positioned by drives that are independently controllable 
from, or independent of, the drive that rotates the seaming rollers 32 and 
34 with respect to a circumferential edge of the lid 16 to be seamed to 
the container body 12. That is, the two drives are separate, mechanically 
unlinked motive means. There are no mechanical cams. Adjustments may be 
made to one drive without affecting the other. In this manner, the seaming 
roller drive (or seaming roller drives if there are two seaming rollers) 
may be positioned more easily, and without having to shut down the machine 
or adjust any gears or the like within the seaming machine. The seaming 
roller drives may even be adjusted while the seaming machine is in 
operation (i.e., "on-the-fly") and without having to stop the seaming 
machine at all. Furthermore, different container sizes may be run through 
the same seaming machine with a minimum of extra tooling. 
The seaming roller drives must be coordinated with the drive that rotates 
the seaming rollers 32 and 34 with respect to a circumferential edge of 
the lid 16 to be seamed to the container body 12. In the present 
invention, this coordination is performed by a controller, preferably, a 
programmable controller which executes a programmable logic control (PLC) 
program. The programmable controller provides significantly more 
flexibility than the conventional approach of mechanically synchronizing 
seaming machine drives. 
Referring again to FIG. 1, the seaming machine 24 includes a first seaming 
roller drive 40 and a second seaming roller drive 42. The first seaming 
roller drive 40 is linked via the roll shaft 36 to the seaming roller 32, 
and the second seaming roller drive 42 is linked via the roll shaft 38 to 
the seaming roller 34. The drives 40 and 42 adjustably position the 
circumferential edge of the respective seaming rollers 32 and 34 toward 
and away from a center axis A.sub.cb of the container body 12, thereby 
positioning the seaming rollers 32 and 34 with respect to the 
circumferential edge of the lid 16 to perform a seaming operation. 
The seaming machine 24 is of the type wherein a seaming chuck holds the lid 
16 firmly against the top end of the container body during the seaming 
operation, and a drive rotates the chuck, thereby causing rotation of the 
container body 12 and container lid 16 (and the chuck) in unison. The 
seaming chuck and drive are schematically shown and are labeled as 44 and 
46, respectively. The present invention may alternatively be used with a 
seaming machine 24 wherein a chuck, container body and lid remain 
stationary, and a drive rotates the seaming roller around the container 
body and lid. In either configuration, the first and second seaming roller 
drives 40 and 42 are independently controllable from the drive which 
rotates the seaming rollers 40 and 42 with respect to the chuck. In the 
disclosed example of the present invention, the first and second seaming 
roller drives 40 and 42 are thus independently controllable from the drive 
46 that rotates the chuck 44, as described in more detail hereafter. 
The seaming machine 24 also has a vertically movable base surface or base 
plate 48 for receiving the container body 12 and for lifting it towards 
the chuck 44. The base plate 48 is lifted by a base plate drive 50 which 
is linked via shaft 52 to the base plate 48. In use, a container body 12 
and an unattached lid 16 resting on the top end of the container body 12 
are placed on the base plate 48, and the container body 12 and unseamed 
lid 16 move toward the chuck 44 a predetermined vertical distance until 
the top end of the container body 12 and lid 16 are held firmly against 
the chuck 44. The top end of the container body 12 and the lid 16 thus 
exert a force against each other which is determined by the final position 
of the base plate 48, as determined by the action of the drive 50. The 
container body 12, lid 16 and chuck 44 remain in the final position during 
the seaming operation. After the seaming operation is completed, the base 
plate drive 50 moves the base plate 48 downward to allow the lidded 
container 18 to be released and to allow a new container body 12 to be 
placed on the base plate 48. The base plate drive 50 is independently 
controllable from the roller drives 40 and 42, and from the chuck drive 
46, as described in more detail hereafter. 
In an alternative embodiment of the invention, the base plate 48 is fixed, 
and the chuck 44 moves vertically downward to hold the container body 12 
and lid 16 firmly together against the base plate 48. In this alternative 
embodiment, the drive 50 would be linked via the shaft 52 to the chuck 44. 
In the preferred embodiment of the invention shown in the figures, the 
seaming rollers 32 and 34 do not move vertically. Accordingly, when a 
container body is properly positioned in the seaming machine 24, it is 
only necessary to move the seaming rollers 32 and 34 toward the center 
axis of a container body 12 to properly position the rollers 32 and 34 to 
perform a seaming operation. However, if the fixed base plate alternative 
embodiment is used, it would be necessary to either link the seaming 
rollers 32 and 34 (and related parts) together with the vertically movable 
chuck 44 to obtain the proper vertical position for the seaming rollers 32 
and 34 for the particular container height, or it would be necessary to 
independently move the seaming rollers 32 and 34 in a vertical direction 
using drives similar to the drive 50. 
The lid 16 is placed on the top end of the container body 12 before the two 
items enter the feed valve 26. The mechanism for placing the lids 16 on 
the succession of container bodies 12 is not shown in FIG. 1. In the 
embodiment of the invention which does not seam in a vacuum environment, 
the lid 16 is placed on the container body 12 before the two items are 
placed on the base plate 48. 
To allow for independent controlling of the respective drives, the assembly 
line 10 preferably includes a programmable controller 54 which executes a 
programmable logic control (PLC) program stored therein. A sample PLC 
program, shown as a ladder diagram, appears in the Appendix. Based on the 
program, control data is output from the controller 54 and sent to the 
respective drives 40, 42, 46 and 50. One purpose of the programmable 
controller 54 is to appropriately position the seaming rollers 32 and 34 
with respect to the circumferential edge of the lid 16 during rotation of 
the container body 12, lid 16 and chuck 44 so as to perform a seaming 
operation. Another purpose of the programmable controller 54 is to control 
the base plate drive 50 so that the base plate 48 is lifted to the 
appropriate final position. The program thus coordinates the seaming 
operation in accordance with the stored program and thereby replaces 
conventional mechanical linkages which perform similar functions. 
The programmable controller 54 includes an operator input panel 56 for 
allowing at least some of the operating values to be entered into the 
program, and a display 58 for interfacing with the operator during 
inputting and for communicating operating status. The programmable 
controller 54 may optionally receive input data from automated measuring 
devices or sensors placed along the assembly line 10. For example, there 
may be a container body diameter sensor 60 and a container height sensor 
62 located prior to the seaming station 14. Data from these sensors may be 
used in place of an operator input values or preset values to set 
parameters of the program which will control the drives. In particular, 
the diameter sensor 60 may be used to control the roller drives 40 and 42 
and the chuck drive 46, whereas the height sensor 62 may be used to 
control the base plate drive 50. 
Roller drives 40 and 42 may periodically require fine position adjustments 
due to wear at contact surfaces or due to play in linkage components. An 
additional feedback sensor 64 may be located after the seaming station 14 
to obtain data regarding the quality of the seam (e.g., its width, body 
hook and cover hook) of seamed containers 18. The feedback data may be 
analyzed, compared to desired values, and used to make the fine position 
adjustments to the appropriate drives. Seamed containers may also be 
manually examined by quality control personnel, and based upon visual 
inspection, fine position adjustments may be manually entered into the 
operator input panel 56. 
Each production run of containers requires specific drive instructions 
based upon the container size (e.g., diameter and height), and desired 
qualities of the seam (e.g., width, body hook and cover hook). These 
factors are processed by the programmable controller 54 and used to create 
a set of instructions. The set of instructions are used to output drive 
control data for each of the seaming machine drives. For example, a 
container body having a three inch diameter and a six inch height requires 
a first set of instructions, including position instructions for the 
roller drives 40 and 42 (to appropriately position the seaming rollers 32 
and 34), rotation instructions for the chuck drive 46 and final position 
instructions for the base plate drive 50, whereas a container body having 
a two inch diameter and a four inch height requires a second set of 
instructions that will be completely different from the first set of 
instructions. 
The set of instructions may be initiated at the start of a production run 
of similar containers to be seamed in the same manner. Alternatively, the 
set of instructions may be modified during the production run based upon 
feedback data from the sensor 64. Another alternative embodiment uses the 
diameter and/or height sensors 60 and 62 to define a new set of 
instructions "on the fly" without having to stop the seaming machine 24. 
In this manner, a single production run may include containers of 
different sizes and/or seam types. 
The container diameter may also be used to automatically select 
"on-the-fly" the appropriate chuck 44 from a plurality of chucks for 
automatic mounting to a seaming machine. The seaming machine 24 shown in 
the figures does not have this capability, although it could be provided, 
if desired. In this manner, a very wide range of container diameters can 
be processed continuously by the same seaming machine without requiring 
any downtime for manually changing chucks. 
Since the programmable controller 54 has complete control over the drive 
46, and because the drive 46 is not mechanically linked to the drives 40 
and 42, the direction of the seaming process can be selected. In the 
seaming machine 24 of FIG. 1, this means that the container body 12 can be 
spun in reverse during a seaming operation, if desired, thereby maximizing 
the strength of certain composite containers depending upon how the 
composite material is wound (e.g., clockwise or counterclockwise around a 
mandrel). Such composite containers would otherwise be weakened by a 
forward rotation during a seaming operation. 
The programmable controller 54 also includes a remote communication module 
80 for bidirectional communication with a remote operator terminal 82. 
This allows an operator at a remote site to operate the seaming machine 
48, program or reprogram the controller 54, and to remotely perform 
diagnostics. 
To simplify the subsequent explanation of the invention, the seaming 
machine 24 is described with respect to only a single seaming roller and 
drive, particularly, seaming roller 34 and its corresponding drive 42. The 
remaining discussion of these components is equally applicable to the 
seaming roller 32 and its drive 40. Also, the position coordination of two 
seaming rollers with respect to each other which is required to create a 
double seam is well known and thus not described in detail herein. 
However, the process generally works as follows: 
(1) The first roller is brought into contact with the lid, and begins to 
roll the lid and the container body. While the first roller is contacting 
the lid, the second roller is not in contact with the lid. 
(2) Next, the first roller is moved away from (and out of contact with) the 
lid, and the second roller is brought into contact with the lid to 
complete the seam. 
(3) When the seam is completed, the second roller is moved away from the 
lid. 
FIGS. 2-4 show detailed views of one preferred embodiment of the drive 42 
and its linkages to the seaming roller 34. Referring to FIG. 2-4, the 
drive 42 is linked via the roll shaft 38 to the seaming roller 34. The 
roll shaft 38 is rotatable about its center axis A.sub.rs. The roll shaft 
38 rotates within a bushing (not shown) of a shaft housing 84. The shaft 
housing 84 is fixed to a housing 86 of the seaming machine 24. The drive 
42 includes a servomotor 68 and a linear actuator 70. The servomotor 68 
has an input for receiving control data from the programmable controller 
54 related to the desired position of the seaming roller 34 with respect 
to the circumferential edge of the container body 12 and the container lid 
16, and an output. The output of the servomotor 68 is connected to the 
linear actuator 70 which translates the servomotor output. The linear 
actuator 70 has an output shaft 72 which is pivotally connected to one end 
of a linking plate 74. The other end of the linking plate 74 is fixedly 
secured to the top surface of the roll shaft 38. Another linking plate 88 
is fixedly secured at one end to the bottom surface of the roll shaft 38 
and at the other end to the seaming roller 34. In this manner, movement of 
the output shaft 72 out of the linear actuator 70 causes rotation of the 
roll shaft 38 in a counterclockwise direction, which, in turn, causes the 
seaming roller 34 to move toward the center axis A.sub.cb of the container 
body 12. FIG. 2 shows the seaming roller 34 in contact with the 
circumferential edge of the lid 16 and thus in the position for performing 
a seaming operation. Likewise, movement of the output shaft 72 into the 
linear actuator 70 causes rotation of the roll shaft 38 in the clockwise 
direction, which, in turn, causes the seaming roller 34 to move away from 
the center axis A.sub.cb of the container body 12. During a seaming 
operation, the seaming roller 34 rotates about its center axis in a 
conventional manner. 
To obtain precise control of the drive 42, the servomotor 68 is preferably 
a stepper motor which accepts control data from a programmable controller, 
and the linear actuator 70 is preferably a ball screw mechanism. 
Alternatively, the linear actuator 70 may be a pneumatic cylinder. Such 
servomotor and linear actuator combinations 68 and 70 are well-known to 
those skilled in the art. Accordingly, further description thereof is 
omitted for purposes of brevity and convenience only and is not limiting. 
Poor seams are sometimes the result of insufficient or excessive force 
being applied between the container body 12 and the lid 16 during the 
seaming operation. Also, when the container bodies 12 are made of 
cardboard or a soft polymeric material, excessive force may cause crushing 
or bulging of the seamed container sidewalls. All of these problems can be 
minimized or eliminated by the present invention. 
Referring to FIG. 1, the drive 50 associated with the base plate 48 is 
preferably similar to the drive 42, and thus also includes a servomotor 68 
and a linear actuator 70. However, the output shaft 72 of the linear 
actuator 70 associated with the drive 50 is directly connected to the 
shaft 52 which extends from the base plate 48. The connection is along a 
common vertical axis. In FIG. 1, the shafts 52 and 72 appear as one 
continuous shaft, even though there are actually two shafts linked 
together. Alternatively, the shaft 52 may be eliminated, and the linear 
actuator's output shaft 72 may be directly connected to the base plate 48. 
This configuration allows for precise, computer-controlled height 
adjustments of the base plate 48. As a result, the drive 50 is 
programmable to cause varying degrees of force to be exerted between the 
container body 12 and the lid 16. Data obtained from the feedback sensor 
64 may also be used to make fine adjustments to the final position of the 
base plate 48. 
To obtain even better control of the force exerted between the container 
body 12 and the lid 16, a pressure sensor 76 may be associated within the 
drive 50 so that an immediate indication of the force may be detected and 
used for feedback control. In this scheme, a desired force is preset by 
the programmable controller 54. In operation, the programmable controller 
54 sends instruction data to the drive 50 to cause movement of the base 
plate 48 toward the chuck 44. The output of the pressure sensor 76 is 
continuously transmitted to the programmable controller 54 and compared to 
the desired force. The comparison data is used to set the final position 
of the drive 50. 
The pressure sensor 76 may be a strain gage attached to the linear 
actuator's output shaft 72. Alternatively, the pressure sensor 76 may be 
an air pressure sensor if the linear actuator 70 is a pneumatic cylinder. 
Controller-driven drives provide significant advantages for the seaming 
machine 24, some of which are discussed below. 
It is sometimes desirable to spot clinch containers during a seaming 
operation. Spot clinching is performed on a seaming machine by 
intermittently engaging and disengaging the seaming rollers from a seaming 
position during rotation of the seaming rollers with respect to the chuck, 
container body and lid. It is difficult, if not impossible, to use a 
conventional seaming machine for both spot clinching and complete airtight 
seaming. In one known technique, a rail substation is used when spot 
clinching with a conventional seaming machine. 
The seaming machine 24 is easily adaptable to spot clinching, and to a 
combination of spot clinching and complete seaming operations. To perform 
spot clinching, it is only necessary to program the controller 54 with 
seaming roller engaging and disengaging instructions during rotation of 
the seaming chuck drive 46. For example, if four clinches are desired, the 
controller 54 would be programmed to engage the seaming roller 34 at 
0.degree., 90.degree., 180.degree. and 270.degree.. Since the seaming 
roller 34 is controlled independent of the seaming chuck drive 46, it is 
not necessary to make any internal adjustments to the seaming machine 24 
to perform spot clinching, to mix spot clinching and complete seaming 
operations in the same machine, or to perform spot clinching followed by 
complete seaming on the same container. 
Preferred Components of Programmable Controller 54 
One preferred embodiment of the present invention is implemented using an 
SLC 500 programmable controller, equipped with preferably two Stepper 
Controller Modules. The SLC 500 programmable controller and the Stepper 
Controller Modules are both available from Allen-Bradley, Milwaukee, Wis. 
The output of the Stepper Controller Module provides the control data for 
the respective drives. A system overview of the SLC 500 family of 
programmable controllers is available from Allen-Bradley and has 
Publication No. 1747-2.30. A User's Manual for the Stepper Controller 
Module is available from Allen-Bradley and has Catalog No. 1746-HSTP1. 
Alternatively, one or three or more Stepper Controller Modules may be 
used, depending upon the needs of the overall system. 
One preferred configuration of the SLC 500 programmable controller has the 
following components: 
SLC 500 Modular Controller with an SLC 5/03 processor. 
Memory Module--Catalog No. 1747-M1 12K Words 
Power Supply--Catalog No. 1746-P2 
24 VDC, 16 input Discrete Input Module--Catalog No. 1746-IV16 
120/240 VAC, 16 output Discrete Output Module--Catalog No. 1746-OA16 
VAC/VDC Relay, 16 output Discrete Output Module--Catalog No. 1746-OW16 
I/O Analog Module--NIO4I and NIO4V 
Operator Terminal--2711 PanelView 550 Operator Terminal, 
Panelbuilder 550 Software 
Remote communication module--1746-BAS Basic Module or 1747-KE Interface 
Module 
The 1746-BAS Basic Module provides limited remote capability. The 1747-KE 
Interface Module provides full remote capability so that all of the 
functions of the programmable controller 54, including the functions of 
adjusting drive instructions based on sensed container types and seam 
feedback data, can be performed remotely. 
A sample ladder diagram for implementing seaming machine control via the 
Stepper Controller Module is shown in the Appendix. The ladder diagram 
performs the following machine control functions: 
1. Configure the Stepper Controller Modules. 
2. Start, stop and jog the seaming machine 24 (sends signal to AC motor 
inverter, also controls machine speed). This function also includes 
controlling power to the chuck drive 46 and the feed valves 26 and 28. 
3. Synchronize machine speeds and stepper motors. 
4. Provide safety stops to protect machinery. 
5. Track production and machine running hours. 
6. Provide an interface with PanelView 550 Operator Terminal to allow for 
seaming roll adjustments. 
7. Provide circuitry to allow valves to be raised and lowered for cleaning 
and maintenance. 
Referring to function 2 above, the chuck drive 46 may also be controlled by 
a stepper motor which would require more precise control signals than 
power on/off signals used in the present embodiment of the invention. 
Sample PanelView 550 display screens and their respective screen summary 
reports are shown in FIGS. 5A-5H. These display screens may be generated 
using a PV550 Keypad and Touch Screen with software version FRN 2.00-2.xx, 
available as Allen-Bradley Catalog Part no. 2711-B5A3. 
Components of Drives 40, 42, 50 
One family of drives which are suitable for use as the drives 40, 42 and 50 
are the ET Series Electro-Thrust Electric Cylinder, available from Parker 
Motion & Control, Parker Hannifin Corporation, Automation Actuator 
Division, Wadsworth, Ohio. Each of these drives have a ball screw and a 
stepper motor. 
Rotations for Seaming Operation 
One preferred embodiment of the invention requires a total of five 
container revolutions to seam a container, 21/2 revolutions for the first 
(initial) seam and 21/2 revolutions for the second (final) seam. The 
precise number of revolutions depends upon a myriad of factors, including 
the desired properties of the containers and the seams. 
Liquid Nitrogen Injection 
Many types of containers are seamed under vacuum so that the container 
interiors have substantially no air after they are seamed. In this manner, 
the container contents cannot become spoiled by exposure to oxygen in air 
trapped in the sealed container. Nuts are one product which is easily 
spoiled by exposure to oxygen. Seaming machines which operate in a vacuum 
environment, such as the seaming machine of FIG. 1, are complex, 
expensive, and difficult to operate, compared to seaming machines which do 
not operate in a vacuum environment. 
One technique that has been developed to avoid having to seam in a vacuum 
environment while still obtaining a substantially air-free container 
interior, is a liquid nitrogen injection process. In this process, a 
container body having a sealed bottom is filled with contents. Liquid 
nitrogen is then injected into the open top of a container body. The 
liquid nitrogen immediately begins to vaporize and drives out 
substantially all of the air (and thus substantially all of the oxygen) 
from the container body. The container body is then covered by a lid which 
may have a removable center foil seal, and the lidded container body is 
delivered to a seaming machine which seams the lid to the container body. 
The conventional liquid nitrogen injection process suffers from many 
problems. One problem is that it is difficult to properly time the process 
so that at the exact time when the lid is seamed to the container body, 
(1) substantially all of the air has been displaced so that the sealed 
container has less than about 2% oxygen, (2) all of the liquid nitrogen 
has vaporized, and (3) no surrounding air has flowed back into the 
container body. Referring to condition (1), if substantially all of the 
air is not displaced, the seamed container will have significant 
quantities of oxygen trapped therein which will accelerate spoilage of the 
contents. Referring to condition (2), if all of the liquid nitrogen is not 
displaced when the container is seamed, the vaporized nitrogen gas from 
the remaining liquid nitrogen will become trapped inside the container and 
will cause the container to visibly bulge. Consumers will not purchase 
visibly bulging containers, assuming that the contents are spoiled or 
defective. Referring to condition (3), if the container body is not seamed 
immediately after all of the liquid nitrogen has vaporized, the 
surrounding air will start to flow back into the container, thereby 
displacing a portion of the nitrogen gas. The resultant seamed container 
will contain a significant quantity of oxygen which will accelerate 
spoilage of the contents. 
Another problem with the conventional liquid nitrogen injection process is 
that it is very wasteful of liquid nitrogen, primarily because the 
vaporization and air displacement process occurs in an open environment 
(i.e., no lid is on the container body). 
FIG. 6 shows an assembly line process 100 which uses liquid nitrogen 
injection in accordance with the present invention to pack goods in seamed 
containers. Each container has a container body 12 and a lid 16 which are 
seamed together by a seaming mechanism of a machine 102 (typically, a 
seaming machine) located at the end of assembly line process 100. Each 
container body 12 has a sealed bottom and an open top as it enters a 
conveyer 104 which moves the container body 12 through the assembly line 
process 100. The assembly line process 100 comprises the following 
sequential steps which are applied to a succession of container bodies 12: 
(1) At a first station 106, each container body 12 is filled with a 
predetermined quantity of goods 108 dispensed from a storage bin 110. The 
storage bin 110 is illustrated in FIG. 6 as a hopper, but may be any type 
of storage facility which has a dispensing passage. 
(2) At a second station 112, each goods filled container body 12 is 
injected with a predetermined amount of liquid nitrogen 114 dispensed from 
a holding tank 116. The predetermined amount of liquid nitrogen 114 is an 
amount which is sufficient to displace substantially all of the air which 
is originally in the container body 12. 
(3) At a third station 118, the open top of each container body 12 is 
covered with a lid 16. 
(4) After each container body 12 exits the third station 118, a lid holder 
120 applies a biasing force against the lids 16 to maintain the lids 16 on 
the container bodies 12 until they reach the seaming mechanism of the 
machine 102. One suitable lid holder 120 is a spring loaded guide rail 122 
which simultaneously applies the biasing force to all lidded container 
bodies 12 traveling along the conveyer 104. The biasing force is 
sufficient to allow a portion of nitrogen gas from vaporization of the 
liquid nitrogen, as well as air originally present in the container body 
12, to escape from the container body, while preventing surrounding air 
from entering the container body 12. The lid holder 120 thus allows each 
of the lids 16 to act as a check valve for its respective container body 
12. In one suitable embodiment of the invention, the biasing force is no 
more than about three pounds of spring pressure on each container body 12. 
The biasing force is selected to prevent the lid 16 from raising more than 
about 1/8 inches off the top of the container body 12 for a typical lid 
which has a vertical thickness of about 1/4 inch. 
Steps (3) and (4) are preferably performed in rapid succession and 
immediately after step (2). In this manner, the amount of liquid nitrogen 
114 used in the process 100 is kept to a minimum because almost all of the 
vaporizing liquid nitrogen 114 is used to expel air trapped inside the 
lidded container body 12. 
Step (4) is performed for a period of time sufficient to allow 
substantially all of the liquid nitrogen 114 trapped within the container 
body 12 to vaporize, and thereby displace substantially all of the air 
originally present therein. Since the lids 16 act as check valves, there 
is no harm in exceeding this period of time. That is, as long as the 
biasing force continues to be applied, no air can reenter the lidded (but 
unseamed) container bodies 12. As discussed above, a conventional liquid 
nitrogen filling process requires precise control between the time when 
liquid nitrogen is injected into the container body and the time when the 
seaming process occurs because air is free to flow back into the container 
body if all of the liquid nitrogen vaporizes before the container body has 
reached the seaming mechanism, and because a bulge may form in a container 
if the container body is seamed before all of the liquid nitrogen has 
vaporized. By freeing the process from the need for tight timing control, 
it is possible to improve the final results of the process (e.g., less 
bulging containers, less likelihood of high oxygen levels), while reducing 
its complexity. 
Furthermore, the process 100 requires substantially less liquid nitrogen 
than conventional filling processes. A conventional filling process 
typically calls for filling container bodies with substantially more 
liquid nitrogen than is necessary to displace the air therein because the 
vaporization and air displacement occurs in an open environment (i.e., no 
lid). Accordingly, much of the nitrogen gas escapes from the container 
body throughout the displacement process. Also, ambient air constantly 
enters the container body throughout the displacement process, thereby 
adding to the total amount of ambient air that must be displaced. To 
compensate for these two factors, a significant quantity of extra liquid 
nitrogen must be injected to ensure that there is a sufficient amount of 
vaporizing liquid nitrogen so that the resultant sealed container has less 
than about 2% oxygen. In contrast to conventional liquid nitrogen filling 
processes, the amount of liquid nitrogen 114 required by the process 100 
of FIG. 6 is an amount which is only slightly greater than the amount 
sufficient to displace substantially all of the air which is originally in 
the container body 12. The amount must be slightly greater to account for 
some leakage as the container bodies travel between the second station 112 
and the third station 114, and between the third station 114 and the lid 
holder 120. 
An alternative embodiment of FIG. 6 may use a clincher as the lid holder 
120. The force applied by the clincher would meet the same criteria as the 
force applied by the spring loaded guide rail 122 discussed above. 
To further enhance the efficiency of the process 100, the container bodies 
12 may optionally be heated from below during step (4) to drive out (i.e., 
vaporize) all of the liquid nitrogen 114. 
The preferred embodiment of the invention uses liquid nitrogen as the 
oxygen displacing gas. However, the scope of the invention includes 
processes which use other inert gases in place of some or all of the 
liquid nitrogen. 
Retrofit of Conventional Seaming Machine 
The present invention is preferably implemented by designing a seaming 
machine which has independently controlled drives for the seaming chuck 
and for the seaming rollers. However, the scope of the invention also 
includes conventional seaming machines (both vacuum and non-vacuum 
environment machines) which are retrofitted with independently 
controllable drives. 
A conventional seaming machine has a single motor, but two power takeoffs, 
one for the drive which rotates the seaming roller with respect to the 
chuck, and one for the drive(s) which control the position of the seaming 
rollers with respect to a circumferential edge of the lid. In one suitable 
retrofit method, the drive which rotates the seaming roller with respect 
to the chuck becomes directly controlled by the programmable controller 
54, and new drives (which are also directly controlled by the programmable 
controller 54) are installed to control the position of the seaming 
rollers with respect to a circumferential edge of the lid. Alternatively, 
a new drive is also installed to rotates the seaming roller with respect 
to the chuck. In addition, another drive (also directly controlled by the 
programmable controller 54) is installed to control container body 
lifting, if precise control of the lifting process is desired. 
It will be appreciated by those skilled in the art that changes could be 
made to the embodiments described above without departing from the broad 
inventive concept thereof. It is understood, therefore, that this 
invention is not limited to the particular embodiments disclosed, but it 
is intended to cover modifications within the spirit and scope of the 
present invention as defined by the appended claims. 
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