US3509686A

US3509686A - Apparatus for packaging in protective atmosphere

Info

Publication number: US3509686A
Application number: US740713A
Authority: US
Inventors: Roger C Bergstrom
Original assignee: Anderson Bros Manufacturing Co
Current assignee: SPX Flow Technology Systems Inc
Priority date: 1968-06-27
Filing date: 1968-06-27
Publication date: 1970-05-05
Anticipated expiration: 1987-05-05
Also published as: DE1931924A1; FR1601184A; DE6925024U

Description

May 5, 1970 R. c. BERGSTROM 3,509,636

APPARATUS FOR PACKAGING IN PROTECTIVE ATMOSPHERE 3 Sheets-Sheet 1 Filed June 27, 1968 u? H/IIH C R-Z PL H22. V

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3 r, 54 M M w l \1 mm 8 4/ 5 a m 5 w s T, MTL IT? o 2 q B Iv a May 5, 1970 R. c. BERGSTROM APPARATUS FOR PACKAGING IN PROTECTIVE ATMOSPHERE Filed June 27, 1968 3 Sheets-Sheet 2 Inn/aria: lflru May 5, 1970 R. c. BERGSTROM APPARATUS FOR PACKAGING IN PROTECTIVE ATMOSPHERE 3 Sheets-Shwt 5 United States Patent 3,509,686 APPARATUS FOR PACKAGING IN PROTECTIVE ATMOSPHERE Roger C. Bcrgstrom, Rockford, 111., assignor to Anderson Bros. Mfg. (30., Rockford, 11]., a corporation of Illinois Continuation-impart of application Ser. No. 596,581, Nov. 23, 1966. This application June 27, 1968, Ser. No. 740,713

Int. Cl. B65b 31/02 US. Cl. 53-112. Claims ABSTRACT OF THE DISCLOSURE A machine is provided for periodically advancing a sheet of plastic material and providing a dwell period at forming, filling and sealing stations. The sealing station includes an evacuable chamber for removal of air and introduction of a protective atmosphere prior to sealing. Control apparatus is provided for sequentially performing these operations independent of time, so the container remains unsealed unless operations are completed within the dwell period.

CROSS-REFERENCE This is a continuation-in-part of application Ser. No. 596,581, filed Nov. 23, 1966, now Patent No. 3,481,100.

BACKGROUND This invention pertains to packaging apparatus and more particularly to apparatus for evacuating a receptacle or container, filling with a protective atmosphere, and closing.

Many products are presently marketed in packages formed by wrapping gas-impervious sheet material around the product and exhausting air from the package. This is known as vacuum packaging. Food products such as cheese and meats are typical of products benfited by this type of packaging since it reduces the tendency of product deterioration by oxidation. More recently, the air in packages has been replaced by an inert or protective gas, e.g. nitrogen, carbon dioxide, and the like. These protective atmospheres further contribute to the preservation of the product. Previous methods have involved the gas flush principle in which the package is partially sealed and the protective gas flowed into the package through a lancet or the like extending into the package. The lancet is withdrawn and the end of the package is subsequently sealed. Another previous method has involved a type of vacuum packaging in which the air is exhausted from the package and partially replaced with a protective atmosphere. The package is then sealed. This causes the package to collapse around the product when exposed to atmosphere.

The parent application discloses a novel method and apparatus for packaging in protective atmosphere. That application contemplates placing a container in an evacuable chamber for a preselected period of time, and evacuating, gasing, and sealing during selected portions of the period. Thus the machine would produce a sealed package whether or not other operations were properly performed. For example, if proper evacuation was not achieved, for any reason, the container would still be gased and sealed. A visual inspection of the package would not reveal such a deficiency in operation. Also, if proper gasing was not accomplished, the container would also be sealed.

SUMMARY The present invention relates generally to packaging apparatus and more particularly to apparatus for packaging in a protective atmosphere. The invention is realized through the provision of an evacuable chamber into which a container is inserted for a preselected dwell period. Means is provided for sequentially evacuating the chamber independent of time, refilling the container with a protective atmosphere independent of time, and sealing a cover member to the container. In this manner, the container remains unsealed unless the sequential operations are performed within the preselected dwell period.

It is an object of the present invention to provide a new and useful packaging apparatus for evacuating a container and refilling with a protective atmosphere.

Another object is to provide a packaging apparatus in which any deficiency in operation is readily apparent from a visual inspection of the package.

Still another object of the present invention is to provide a packaging apparatus in which the container remains unsealed unless the evacuating, gasing, or sealing operations are properly accomplished within a preselected period.

These, and other objects and advantages of the present invention, will become apparent as the invention becomes better understood from the following detailed description when taken in conjunction with the accompanying drawings.

DRAWING FIG. 1 is diagrammatic illustration of an embodiment which incorporates the present invention;

FIG. 2 is a diagrammatic view of the electrical controls;

FIG. 3 is a diagrammatic view of the pneumatic controls;

FIG. 4 is a view, partly in cross-section and partly in elevation, of the sealing station and evacuable chamber and showing the relationship of the parts in the sealing position;

FIG. 5 is a view taken generally along line 55 of FIG. 4 and showing a moved position in phantom lines;

FIG. -6 is a sectional view taken along broken line 6-6 of FIG. 4 and showing the relationship of the parts during the evacuating and gasing operations;

FIG. 7 is a view similar to FIG. 6 but with the apparatus in sealing position; and

FIG. 8 is a perspective view of a suitable package utilized in the present invention.

Reference is now made more particularly to the drawings which illustrate the best presently known mode of carrying out the invention and wherein similar reference characters indicate the same parts throughout the several views.

As diagrammatically illustrated in FIG. 1, a roll 10 of thermoplastic material is supported adjacent one end of the machine. A web 11 is advanced longitudinally of the machine past successive stations. Heating

heads

12 and 13 heat the web 11 so that it may be formed into any desired shape. At the next station, a cup-like member, generally designated C, is pressure formed in web 11 by a mandrel 14 adjacent one side of the web and pressure adjacent the other side. It is contemplated that vacuum forming may also be utilized, and the term pressureformed should be taken as including pressure forming, vacuum forming, and other types of forming. Mandrel 14 moves in the direction of arrows 15 between a forming position generally contiguous to the web and a second position (shown in dashed lines) removed from the web so that the web may be intermittently advanced. Web advancement is accomplished by a gripper 16 which is recinrocated by a piston 17 in the direction of arrows 18.

While other Shapes are contemplated, a suitable cuplike container C is shown in FIG. 8. The container has a bottom 22 and a side wall 23 which advantageously slopes uniformly upwardly from the bottom 22. The upper end of the side wall is preferably coplanar and defines the open end of the container. An outwardly projecting flange extends outwardly around the periphery of the side wall and at the upper end thereof. The outwardly projecting flange advantageously includes an inner portion 28 and an outer portion 29 stepped above the inner portion a preselected distance. The inner portion 28 is coplanar with the upper end of the side wall and extends a distance outwardly therefrom. The outer portion 29 has its upper face at a level above the upper face of inner portion 28 and defines a plane parallel thereto. As can be seen in the drawings, a series of containers C is advantageously formed in web 11 in such a manner that adjacent outer portions 29 are interconnected.

After the container C is formed in web 11, it is advanced to a third station where an opening 30 is formed in the flange member. The opening is formed by means of a punch 32 and a die 34 (see FIG. 1) mounted at said third station. It is contemplated that the opening may also be formed at the aforedescribed forming station, if desired. Preferably, opening 30 is formed in the outer flange portion 29 and in the interconnecting portion between two adjacent containers. As shown, opening 30 is closer to one container for a purpose which will hereinafter become apparent.

At a fourth station, a preselected quantity of a product P is dispensed into the container C. While the product P may be any type which may be handled and packaged, in accordance with the present invention it would be a product advantageously packaged in a protective atmosphere such as carbon dioxide, nitrogen, argon, active nitrogen, or the like.

Simultaneously with the above operation, a second roll of thermoplastic material 40 is supported on the machine and a web 41 withdrawn therefrom. In similar fashion, the web 41 is heated by

heating members

42 and 43. An inner cover, generally designated I, is pressure-formed by mandrel 44. The web 41 is advanced to a cutting station where cutters 45 accurately cut the inner cover I to its required shape. Preferably, the inner cover I is shaped to lie contiguous to the inner flange portion 28 and span the open end of container C. The inner covers I are gripped by a reciprocating head 46 which deposits each inner cover on a respective container C which has been filled with product P.

In the embodiment illustrated, inner cover I includes a spanning portion 52 extending adjacent the side wall 23 of container C and at a level below the upper end thereof. Wall 53 extends upwardly from spanning portion 52 and tapers outwardly generally parallel to side wall 23 of the container. The taper of side wall 53 advantageously provides a self-centering action when the inner cover is placed in position and allows the inner cover to nest in the position illustrated in the drawings with its wall 53 generally contiguous to side wall 23. A peripheral portion 54 extends outwardly from wall 53 and is engaged with inner flange portion 28 of the container C. An arched handle 56 is formed across the spanning portion 52 to provide a grip for removal of the inner cover I. It will be noted that the handle is hollow and is above the level of the spanning portion at all points. At opposite ends of the hollow handle 56 are

channels

58 and 59 which are preferably formed in wall 53 and peripheral portion 54. As illustrated, channel 58 is preferably formed in the area of opening 30 to provide communication between the opening and the interior of container C. The advantages of

channels

58 and 59 will hereinafter become more apparent.

In some packages, inner cover I may be omitted and the entire flange member may be planar. The

channels

58 and 59 are not required in such an arrangement; however, if desired, the channels may then be advantageously formed in the flange member and extending from opening 30 to side wall 23.

A third roll 60 is supported on the apparatus, and a thin, flexible sheet 61 is withdrawn therefrom. Sheet 61 is advantageously stretchable and adapted to be sealed to the flange member of container C along a preselected peripheral area. Preferably, compatible thermoplastic materials are selected for Web 11 and sheet 61, and the sealing may be accomplished by heat sealing. It should be understood, however, that other materials may be utilized and that other sealing methods may be used. In some embodiments, it is preferable that sheet 61, which provides the cover member of the finished package, be flexible for a purpose hereinafter to become apparent. Sheet or cover member 61 is placed in juxtaposition to the flange member, as shown, and the container C, inner cover I, and cover member 61 advanced to a sealing station which includes an evacuable chamber, generally designated X, and illustrated in detail in FIGS. 4-6. At chamber X, the air is evacuated from the chamber and container C, a protective atmosphere of a preselected type is introduced through the opening 30 into the container C, and the cover member 61 is thereafter hermetically sealed to the outer flange portion 29 and inwardly of the opening 30. The apparatus will hereinafter be described in detail.

At this point, a plurality of sealed packages is interconnected in a continuous web as illustrated in FIG. 1. The Web of scaled packages is advanced to another station 64 where the packages are cut from the web by

cutters

65 and 66. The completed packages are deposited on a conveyor 68, and the waste portion of the web is fed out of the machine. At cutting station 64, the continuous web is conveniently cut inside of the outer extremity of the seal area effectuated at the sealing station to insure that the seal between cover member 61 and outer flange portion 29 extends entirely to the edge. This provides a very neat package with no loose outer cover. If desired, a peel portion of any desired length may be formed outwardly of the seal area in any convenient manner.

As explained above, vacuum packing has the disadvantage of collapsing the package when it is exposed to atmospheric pressure. Additionally, a certain residue of air is necessarily left in the package, and this can cause some deterioration of certain products, such as meat. The gas-flush process allows a protective atmosphere to be flowed into the package; however, in the past this has necessitated partially sealing the package and introducing the protective atmosphere through a lancet or the like extending into the container. It is desirable to reduce the residue of air in the container to a minimum, flow a protective atmosphere into the container, and thereafter hermetically seal the package. In accordance with the present invention, these operations are sequentially performed, and each successive operation is accomplished only after successful completion of the preceding operation. These operations are advantageously performed at the sealing station illustrated in FIGS. 4, 6 and 7.

As seen in FIG. 4, the sealing station includes a frame member 71 which forms a partial enclosure. Frame member 71 is supported by

support bars

72, 72 which extend longitudinally of the machine, as shown in FIG. 1. A sealing head 74 is rigidly supported on the frame member 71 by means of columns 75 and mounting brackets 76. The evacuable chamber X is movably mounted at the sealing station and includes an upper portion 78 and a lower portion 79. The upper portion 78 is resiliently mounted on the mounting bracket 76 by means of a plurality of springe 81. The lower portion 79 is mounted for movement with a movable frame member 82 in any convenient manner. In the embodiment illustrated, movable frame member 82 is mounted for movement relative to stationary frame member 71 and, for this purpose, is slidably mounted on slide rods 84, 84'. The movable frame member 82, and hence the lower portion of the evacuable chamber 79, is movable between an open position (not shown) and an intermediate position (shown in FIG. 6) by actuation of pneumatic cylinders 86, 86'. From the intermediate position, the lower portion 79 is movable to its upper position (shown in FIG. 7) by actuation of a pneumatic cylinder 88 as described. At the open position, the container C, intercover I, and cover member 61 are advanced into the evacuable chamber by the operation of gripper 16 which advances sheet 11 in the direction indicated by arrow G in FIG. 1. As previously described, the advancement of the sheet of container material is intermittent and thus these items are disposed in the evacuable chamber for a period of time hereinafter sometimes called a preselected dwell time.

From its lower position, lower member 79 is movable to the intermediate position engaged with upper portion 78 to form a generally air-tight enclosure (FIG. 6). As shown, a gasket 89 is conveniently utilized to insure that the enclosure is substantially gas tight. At this position evacuation of the chamber X is performed and, thereafter, the container is refilled with an inert gas or protective atmosphere which is introduced through passage 195 communicating with opening 30. The protective gas flows through the

channels

58 and 59 to fill the container and into the chamber X. If no inner cover I is used, a flexible cover allows the gas to flow into the container as described in the aforesaid opplication Ser. No. 596,581. After gasing, the lower portion 79 is moved to its upper position to engage the cover member against sealing head 74.

As can be seen, the sealing head 74 is disposed in a cavity within the upper portion of the evacuable chamber and the sealing head has a projecting flange 74' having a shape generally corresponding to the flange member of the container for sealing the cover member 61 thereto. The sealing head may be heated in any convenient manner; or may be adapted for pressure sealing, if a pressure sensitive adhesive is utilized. Ultrasonic or high frequency sealing and other sealing methods may also be used, if desired. As best seen from FIG. 7, when the lower portion 79 moves to the sealing position, it pushes the resiliently mounted upper portion 78 with it and thereby maintains the air tight enclosure.

As stated above, movement of the evacuable chamber X to the sealing position is accomplished by actuation of pneumatic cyclinder 88. The apparatus which cooperates with pneumatic cylinder 88 to accomplish this operation will now be described. As shown in FIG. 4, a cam support block 100 is rigidly mounted on the machine in any convenient manner.

Knuckle joints

101 and 102 are provided with

slots

101 and 102, respectively, for straddling the block 100 in one position. As shown

knuckle joints

101 and 102 are each provided with cam faces at their bottom sides. The knuckle joints are rotatably mounted at the bottom of

slide rods

84 and 84 for movement between one position shown in phantom in FIG. 5, and another or camming position shown in full lines in FIGS. 5 and 6. At the one or straddling position, slots 101' and 102' straddle the cam block 100. to allow the lower portion of the evacuable chamberto be moved between the lower and the intermediate positions by pneumatic cylinders 86, 86'. When at the intermediate position, the cam faces of the knuckle joints are at the upper face of cam block 100. When the pneumatic cylinder 88 is actuated, it rotates the knuckle joints to their camming position which forces the movable support frame 82 upwardly a pre-selected distance and thereby moves the evacuable chamber to the sealing position.

As previously described, the machine advances the con tainer into the evacuable chamber where it is disposed for a preselected dwell period. In accordance with the present invention, evacuation, gasing, and sealing are sequentially performed without regard to time, whereby the container remains unsealed unless the operations are successfully performed within the dwell period. In other words, this procedure assures that a sealed container is one which has had the operations successively performed.

The controls for achieving this desirable result are diagrammatically illustrated in FIG. 2. As shown, the control means includes an electrical circuit having a supply line 111 and a return line 112. A timing mechanism 113, conveniently operated in timed relation with the reciprocating mechanism of the machine, is operative to supply power to line 111 during the preselected dwell period and to cutoff the power at the end of the dwell period. A conductor 114 extends between lines 111 and 112 and has a limit switch 115 interposed therein. Limit switch 115 is operated by the movement of the lower portion 79 of the evacuable chamber to its intermediate position. When switch 115 is thus closed, a circuit is completed and actuates solenoid 116 to start evacuation of the chamber. A light 117 is wired in parallel to the switch 115 and solenoid 116 and may be located at any convenient position to indicate that this operation is being performed.

A pressure-sensitive switch, indicated generally at 120, is responsive to the pressure in the evacuable chamber X and includes a normally open switch 120a interposed in a conductor 121 and a normally closed switch 12% interposed in conductor 122. Both conductors 121 and 122 extend between lines 111 and 112 as shown. When a preselected vacuum is drawn, a movable diaphragm 1200 closes switch 120a and completes the circuit to a solenoid CR-l and a light 123 which indicates the gasing step. The preselected vacuum is preferably adjustable by suitable adjusting apparatus on the pressure-sensitive valve 120. Solenoid CR-l operates relay switches R-la, R-lb, R-lc and R-1d. Relay switch R-lb is interposed in conductor 144 and is opened by solenoid CR-l thereby breaking the evacuation circuit to cease evacuation. Normally open relay R-lc is interposed in line which is connected to

conductors

114 and 124 to provide a holding circuit for solenoid CR-l. Normally open relay R-1a is interposed in conductor 131 and, when actuated by the solenoid CR-l, completes the circuit and actuates solenoid 132 to start the gasing operation.

When the pressure of the gas or inert atmosphere reaches a preselected level which may be regulated by adjustment of pressure-sensitive valve 120, switch 12% is returned to its closed position thereby completing the circuit through relay switch R-ld and conductor 122, and actuating solenoid CR-2. Solenoid CR-2 operates relay switches R-2a, R-2b, and R2c. The opening of normally closed relay switch R-2a breaks the holding circuit to solenoid CR-l and thereby interrupts the gasing operation. Relay switch R-2b is interposed in conductor 136 and, when closed, creates a holding circuit for solenoid CR-2 and also lights light 137 to indicate that the sealing operation has begun. Relay switch R-2c is interposed in conductor 138 and, when closed, completes a circuit to solenoid 139 which causes actuation of pneumatic cylinder 88 and moves the evacuable chamber X to the sealing position. Wired in parallel with solenoid 139 is another solenoid 141 interposed in line 142. A limit switch 143 is also interposed in line 142 and is closed by movement of the evacuable chamber to the sealing position. This completes the circuit and actuates solenoid 141 which vents the evacuable chamber to atmosphere thereby allowing the chamber to be subsequently opened.

As seen in FIGS. 4, 6, and 7, the evacuable chamber X is provided with an outlet conduit 187 conveniently located in the upper portion 78. The chamber can be placed in communication with the atmosphere or with a vacuum pump (not shown) by means of a valve 186 connected to outlet conduit 187, pump conduit 188 and atmosphere conduit 189. Valve 186 may also be moved to a position, shown in phantom in FIG. 6, to block flow through conduit 187 as during the gasing operation. The aforementioned solenoid 116 moves the valve 186 to evacuation position (FIG. 6), solenoid 132 moves the valve to the blocking position, and the solenoid 141 moves the valve to position for venting to atmosphere (FIG. 7).

To increase the versatility of the machine, a manual switch 151 is provided and is selectively movable from a position interposed in conductor 121 and a position shown in phantom where it is interposed in a pass-by line 152. When moved to the position in line 152, switch 151 causes a by-pass of the gasing controls and allows the machine to be used for vacuum packaging. In other words, the operation consists of evacuation and then sealing. Another switch 153 is provided in a by-pass line 154 and, when closed, causes lay-passing of both the evacuation ad the gasing operations. In other words, upon supplying current to line 111 when switch 153 is closed, a circuit is completed through solenoid CR2, and the machine immediately seals the cover to the container without evacuation or gasing of the container.

A suitable pneumatic circuit is diagrammatically illustrated in FIG. 3. As shown, a supply reservoir 150 contains a supply of air under pressure and has a supply line 151 leading therefrom. Supply line 151 has branches 151a and 151b. A two-way valve 154, operated by a solenoid 155 controls the flow of air from branch 151b to

pneumatic cylinders

86 and 86. Solenoid 155 is operated at the beginning of the preselected dwell period to move the valve 154 from the position illustrated to its other position, This supplies air under pressure to

lines

156 and 157 and thereby actuates pneumatic cylinders 86 and 86'. A second two-way valve 161 is operated by the aforedescribed solenoid 139 to move the valve from the position shown to its second position. This supplies air from branch 151a to line 162 and thereby actuates pneumatic cylinder 88. After the scaling is accomplished and timer 113 discontinues supplying current to the control circuit, the valve 161 is returned to the position shown and air is supplied to line 163 to move pneumatic cylinder 88 in the opposite direction. Valve 154 is also returned to the position shown and air is supplied from branch 151b through

lines

166 and 167 to return

pneumatic valves

86 and 86 to the position illustrated and thereby move lower portion 79 of the chamber to its lower position.

It is now deemed obvious that the present invention provides an apparatus in which containers are intermittently advanced to a sealing station and which provides a dwell period thereat. During the dwell period, the operations of evacuation, gasing, and sealing are performed independent of time so that a sealed container is a sign that all operations have been successfully performed.

The invention, in its broader aspects, is not limited to the specific mechanism shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention, and without sacrificing its chief advantages.

What is claimed as new is:

1. An apparatus for packaging in a protective atmosphere including: an evacuable chamber having an upper portion and a lower portion movable relative to each other between an open position and a substantially airtight closed position; means for moving at least one container and cover member into and out of the chamber while said portions are in open position and for providing a dwell period of preselected duration in the chamber; means for moving the chamber portions to closed position after the container and cover member are in the chamber; evacuating means for reducing the pressure in the chamber to a first preselected level independent of time; refill means for introducing the protective atmosphere into the container and increasing the pressure to a second preselected level independent of time; a sealing head disposed in the chamber for sealing the cover memher to the container; operating means for sequentially operating the evacuating means, refill means, and sealing head independent of time; and means for energizing the operating means only during the preselected dwell period so that the container remains unsealed unless the sequential operations are performed within the preselected dwell period.

2. An apparatus for packaging in a protective atmosphere as set forth in claim 1 wherein the operating means includes pressure-actuated switching means responsive to the first preselected level to cease operation of the evacuating means and to start operation of the refill means, and responsive to the second preselected level to cease operation of the refill means.

3. In an apparatus for packaging in a protective atmosphere including a forming station for forming a container in a sheet of formable plastic material; a filling station for depositing a material to be packaged in the container; a sealing station for hermetically sealing a cover member to the container; and means for sequen tially advancing the sheet to the stations and for providing a dwell period of preselected duration at the stations; the improvement comprising: an evacuable chamber at the sealing station for receiving the container and cover member therein during the dwell period; evacuating means for reducing the pressure in the chamber to a first preselected level independent of time; a source of protective atmosphere; refill means for introducing the protective atmosphere into the container and increasing the pressure therein to a second preselected level independent of time; a sealing head disposed in the chamber for sealing the cover member to the container after the refill means has operated; and control means for sequentially operating the evacuating means, refill means, and sealing head independent of time whereby the container remains unsealed unless the operations are performed within the preselected dwell period.

4. The combination of claim 3 wherein the evacuable chamber includes upper and lower portions movable relative to each other between a closed position to provide a substantially gas-tight chamber and an open position for entry of the container and cover member, and means for moving the portions to the closed position at the beginning of the dwell period and to the open position at the end thereof; and wherein the control means includes first means responsive to the portions at their closed position to start operation of the evacuating means.

5. The combination of claim 4 wherein the lower portion of the chamber is arranged to support the container in the closed position, wherein the sealing head is initially spaced above the lower portion of the chamber, and including moving means responsive to the control means for effecting relative movement of the sealing head and the lower portion of the chamber to engage the cover member with the sealing head for the sealing operation, and wherein the control means includes second means responsive to the relative movement of the sealing head and the lower portion of the chamber to vent the chamber to atmosphere.

6. The combination of claim 5 wherein the control means includes pressure-actuated switching means responsive to the first preselected level to cease operation of the evacuating means and to start operation of the refill means, and responsive to the second preselected level to cease operation of the refill means and to start operation of the moving means.

7. The combination of claim 6 wherein the first means includes a first switch actuated by the relative movement of the portions to their closed position, the second means includes a second switch actuated by the relative movement of the sealing head and the lower portion of the chamber, the control means includes an electrical circuit connecting the first and second switches and the pressure actuated switching means in parallel, and the control means also includes means for supplying current to the electrical circuit only during the preselected dwell period.

8. The combination of claim 3 wherein the forming station forms a container having an out turned peripheral flange at the open end thereof; the evacuable chamber includes upper and lower portions movable relative to each other between an open position for receiving the container and cover member and a substantially air-tight closed position, the lower portion being arranged to support the peripheral flange and container; and including means for positioning the cover member in juxtaposition to the peripheral flange, means for forming an opening in the peripheral flange prior to entry of the container into the evacuate chamber; and wherein the evacuating means communicate with the chamber outwardly of the container, and the refill means has an outlet at the underside of the flange and communicating with the flange opening for introducing the protective atmosphere therethrough.

9. The combination of claim 8 wherein the sealing head is initially above the container and cover member, the sealing head and lower portion being movable relative to each other to contact the sealing head with the cover member, and the sealing head being shaped to seal the cover member to the container along a seal line located inwardly of the flange opening.

10. The combination of claim 9 including moving means for moving the sealing head and cover member relative to each other; and wherein the control means includes pressure-responsive switching means responsive to the first preselected level to cease operation of the evacuating means and to start operation of the refill means, and responsive to the second preselected level to stop operation of the refill means and to start operation of the moving means.

References Cited UNITED STATES PATENTS 3,061,984 11/1962 Mahafiy 53-112 X 3,347,011 10/1967 Lovas et a1. 53--112 X TRAVIS MCGEHEE, Primary Examiner