US2277288A - Method of sealing containers - Google Patents

Description

March 24, 1942. s BERCH 2,277,288

METHOD OF SEALING CONTAINERS Filed Nov. 30, 1939 2 Sheets-Sheet 1 0 1 i //v Vf/VTOA JAMl/[L h! 0596/1 0K 7 /7 jaw ATTOR/Vf) March 24, 1942.

s. H. BERCH 2,277,288

METHOD OF SEALING CONTAINERS Filed NOV. 50, 1939 2 Sheets-Sheet 2 //V l/[N 70R JAMU EL hi 552671 ATTORNEY Patented Mar. 24, 1942 I g UNITED STATES PATENT OFFICE METHOD or SEALING CONTAINERS Samuel H. Berch, Beverly Hills, Calif.

Application November 30, 1939, Serial No. 306,924

1 Claim. (Cl. 226-51) This invention relates to'the packaging of mashowing the creasing means for the mouth of terials and particularly pertains to a method and the container. means of sealing and vacuumizing containers. Fig. 3 is a view in end elevation showing the In the packaging of various products, such for means for spreading and creasing the mouth of example as food and the like, as disclosed in my the bag. co-pending application entitled Packing machine, Fig. 4 is a view in vertical section showing the Serial No. 279,150, filed June 13, 1939, it has means for folding the mouth of the container been contemplated to utilize a fiexible bag-like and heat sealing the same. container having an outer lamina substantially Fig. 5 is an enlarged view in section showing non-stretching, said lamina carrying a coating or ,l0 the specific construction of theheat sealing inner lamina of material such-as that known means.

in the trade as Pliofilm or Pliolite," in both of Fig. 6 is a fragmentary view showing the opwhich instances the inner surface of the conerating mechanism for the folding members. tainer lends itself to heat sealing when contact- Fig. 7 is a view-in diagram indicating the ap-' ing faces are held together under conditions of J pearance of the mouth of the container in plan heat and pressure. Whena container of this when it is creased.

type is used in the packaging of food products, Fig. 8 is a view in plan showing the mouth such for example as coffee, which comprises the of the container and the spreading means by ground coffee and associated dust-like particles, which the container is opened after it has been it has been found that a problem is presented creased.

in order to prevent the dust-like particles from Referring more particularly to the drawings, being drawn between the surfaces to be heat Ill indicates a frame structure upon which a-pair sealed. It will be evident that the presence of of sprocket shafts H and I2 are journaled. these small particles of extraneous matter will Mounted on these shafts are sprockets l3 and prevent a uniform tight and homogeneous heat 25 H whichcarry a series of molds l5. 'I' hese seal to be produced, and that as a result the molds are preferably rectangular in sectionand vacuum seal may not be perfect and may permit are of the general type and construction shown the seepage of air into the container to dein my application Serial No. 279,150, filed June teriorate the product. It is the principal ob- 13, 1939, and my application Serial No. 283,794

ject of the present invention, therefore, to pro- 3 filed July 11 1939. The molds were also subvide a method and means of forming, vacuumstantially rectangular in vertical section. The izing and sealing a package of the character debag or container to be utilized in this process scribed in a manner to insure that the meeting -may for example be of the type shown in my surfaces to be sealed will be free of any exissued patent entitled Method and means of traneous matter, and that when heat and prespackaging food products and the like, U. S. Patsure are applied to the surfaces a continuous ent No. 2,102,716 issued'December 21, 1937. This homogeneous seal will result. type of container is flexible and is characterized The present invention contemplates the proas having a relatively non-stretching outer wall vision of a mold within which a package of the and an inner wall made of a thin sheet of type described may be placed and filled with a f Pliofilm or the like held to the outer wall by product to be sealed therein, thereafter creasing an intermediate layer of adhesive or a product the mouth of the container to form seams which known to the trade as Pliolite. In some'inwill afterward be folded, then releasing the crease stances it may be deemed desirable to eliminate to permit the mouth to open. then subjecting the inner layer of Pliofilm and use a layer of the container with its contents to a vacuum 210- Pliolite directly applied to the outer wall withtion and thereafter recreasing, heat sealing and out the use of an intermediate adhesive. It is folding the mouth of the container while the a characteristic of both Pliofilm and Pliolite container and its contents are being subjected to that. .when their surfaces are contacted under the vacuum action. I action of heat and pressure that. cohesion will The invention is i lustrated by way of exam take place to make a tight and leak-proof Joint ple in the accompanying drawings, in which: or seam. A structure for creating this result Figure 1 is a diagrammatic view in side elewill be hereinafter described, and is shown in vation showing the sequence of operation of the Figs. 4, 5 and 6 of the drawings. present invention. The molds l5 are mounted upon an endless Fig.2 is a fragmentary view in front elevation chain conveyor l6 which is led around the sprockets l3 and M. This successively carries the previously applied containers H to a filling station i8, where a product is placed within the containers, and to a station l9, where the mouth of the container is spread lengthwise. This will draw the side faces of the mouth together and will pull the end faces of the mouth outwardly so that the opposite halves of the end face at each end will be drawn tightly and end creases in the mouth will be formed.

Referring to Fig. '7 of the drawings, it will be seen that spreading fingers and 2| are disposed in the mouth of the container and midway the width thereof so that the fingers will contact walls 22 and 23. The opposite side walls 24 and 25 will be also indicated by solid lines. When the spreading fingers are moved to their dotted line positions it will be seen that the mouth portion of the container will be drawn together, as indicated in dotted lines, and that an end crease 26 will occur intermediate the length of the walls 22 and 23. The structure for performing this operation is indicated particularly in Figs. 2 and 3 of the drawings, where it will be seen that the main frame It! carries a crosshead 21 which overhangs the path of travel of the molds Hi. This crosshead carries a pair of spreading fingers 28 and 2| which have a gear rack 28-formed on their faces to engage pinions 29. The pinions 28 are in turn driven by a horizontal extending gear rack 38 which is mounted upon the crosshead 21 and is here shown as connected with the arm of a bell crank. The opposite arm of the bell crank carries a roller 32 which engages an eccentric cam 33 mounted upon a cam shaft 34. The cam shaft 34 is driven in synchronism with the drive of the conveyor chain I6, which is intermittently driven.

By reference to Fig. 2 of the drawings, it will be seen that the side walls 22 and 23 are indicated in their normal dotted line position, and that when the fingers 20 and 2| are moved outwardly as driven by the rack 38 they will stretch the mouth of the container lengthwise, as indicated particularly in Fig. '7. It is to be understood that when this operation takes place the container is filled substantially to the dotted line 11 indicated in Fig. 2 of the drawings, and that the stretching and creasing of the mouth occurs above that level and also above the mouth of the mold 5. It will therefore be seen that when the mouth of the, container is stretched, as

indicated in Fig. 2 of the drawings, it will occur as indicated by dotted lines in Fig. 7, at which time creases 26 will be formed.

In my application Serial No. 283,794 vacuum is applied to the container when the mouth of the container has been stretched and creased and while folding and sealing action is being produced by the structure shown in Fig. 4 of the drawings. In the present instance the folding and sealing action is deferred until after the creased mouth of the container has been reopened and vacuum applied to the container and its contents. This insures that the mouth of the package will be open prior to the vacuumizing action so that thorough vacuumization may take place. This is performed at the station 35, at which time the spreading fingers 28 and 2| have been withdrawn from the mouth of the container. It may occur that due to the character of the walls of the container they will partially spread and tend to return to their original uncreased position, as indicated by solid lines in Fig. 7, or that it will be necessary to restore the mouth of the container positively toward its original open position by introducing a set of pins 36 which when moved to the corners of the structure will act to spread the mouth of the container to its original opened position, although they will not draw with sufficient tightness to stretchthe crease 26 out of the end walls 22 and 23. With the mouth of the container re-opened the structure is then carried to a vacuum chamber 31 within which the package will be vacuumized. At said station a second bag stretching and creasing unit, such as shown in Fig. 2, occurs so that after a suitable vacuum action has been created the mouth of the container may be drawn again to its'collapsed position, as indicated in dotted lines in Fig. 7. It has been found in practice that if the creases 26 have been previously made before vacuum action takes place it is much easier to fold and seal the mouth of the container than if this is done for the first time immediately preceding vacuumization. After the structure has been subjected to vacuum action and the mouth of the container has been again creased along the creases 26 the folding fingers 38 and 38 move into operation. These fingers are mounted upon shafts 40 and 4| which are parallel to the sides 24 and 25 of the container and are offset therefrom. The fingers, as particularly shown in Fig. 5 of the drawings, are of an overall length greater than the width across the container from side wall 24 to 25, thus they will overlap each other to form a final fold and will hold the walls togetheras the container is heat sealed.

The finger 38 is formed with an upper inclined face 42 against which heat sealing action takes place. This inclined face continues to the free end of the finger in an upper fiat face 43. An end face 44 defines the free end of the finger 38. The end face 44 falls substantially along thevertical median line of the container. The lower face of the finger 38 is formed by a fiat face 45 which bears against the folded and formed container. Opposed to the end face 44 of the finger 38 is a parallel shoulder 46 upon the finger 39. This shoulder occurs substantially along the median line of the container when the two fingers are folded downwardly, as indicated in Fig. 5 of the drawings, and cooperates with the shoulder 44 of the finger 38 to provide an intermediate space into which the side walls of the container may be clamped. Extending horizontally from the upper edge of the shoulder 46 is a flat face 41 which, when the fingers are in their folded positions, lies parallel to the fiat face 43 of the finger 38 and cooperates therewith to hold the wall sections of the container together. Mounted upon the finger 39 and overhanging the free end thereof is a rubber element 48 which presses downwardly against the folded portionof the container which lies upon the face 43 of finger 38 and yieldably holds the same. The end portion of the folded and clamped container walls then extend upwardly and lie along the inclined face 43 where a heat sealing operation will take place.

The heat sealing structure includes a sealing bar 49 which may be pressed down against the folded side walls of the container and against the inclined face 42. The contacting portion of the sealing bar 48 is represented by a curved convexed portion 50. This makes a relatively small contact with the parts to be sealed and insures that while heat and pressure are applied on a relatively small width of seam extending lengthwise of the folded portion that the material which is rendered plastic by the action of the heat may tend to flow freely at opposite sides of the contacting faces and produce an air-tight seal at both sides of the line of contact. This insures that the seam which is formed will be strong and air-tight to hold a vacuum. After this sealing operation has been performed the vacuum action may be interrupted and the vacuum sealed package may be then removed from the mold.

It will thus be seen that by the method of sealing here disclosed it is possible to eliminate the accumulation or entrapment of extraneous matter in the seal being formed and to produce the seal in a manner to insure that heat and pressure may be applied along a seam area while permitting the materials producing cohesion to accumulate at each side of that area to form strong vacuum-tight seams.

While I have shown the preferred method of performing my invention and preferred means of practising the same, it is to be understood that various changes may be made in the combination, construction and arrangement of parts of the apparatus and the steps of the method by those skilled in the art without departing from the spirit of the invention.

Having thus described my invention, whatI claim and desire to secure by Letters Patent is:

A method of vacuum sealing a bag-like package, characterized as having walls which are flexible and pliable, the inner surfaces of the walls having thereon a material which when said surfaces are pressed together under the action of heat will form a vacuum-tight joint, said method comprising placing a container in a mold with its open mouth portion extending above the level of the mouth of the mold, thereafter filling the container with a product to be packed up to the level of the mouth of the mold, then stretching the mouth of the container by applying pressure upon points on the side walls intermediate the length of said walls, whereby said side walls and the opposite side walls will be stretched and drawn together and vertical creases will be formed in the side walls against which pressure was applied, thereafter releasing said pressure whereby-the mouth of the container may be opened, t applying vacuum to the container and its co tents to vacuumize the same, thereafter again'closing the mouth of the container between the previously formed creases, and then applying heat and pressure to said closed mouth, whereby the material coating the inner surfaces of the container will form an hermetically sealed seam.

' SAMUEL H. BERCH.

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