US2555315A - Method of producing containers - Google Patents

Description

' Filed July 5, 1945 2 Sheets-Sheet 1 June 5, 1951 CARROLL 2,555,315

METHOD OF PRODUCING CONTAINERS mmvrozc Mfi M v %M M B June 5,1951 J. P. CARROLL 2,555,315

METHOD OF PRODUCING CONTAINERS Filed July 5, 1945 I 2 Sheets-Sheet 2 u V i A r roe/V5245 Patented June 5, 1951 METHOD OF PRODUCING CONTAINERS Joseph P. Carroll, Maplewood, N. J., assignor to American Can Company, New York, N. Y., a corporation ,of New Jersey Application July 5, 1945, Serial N 0. 603,325

2 Claims.

The present invention relates to a method of producing liquid-proof containers for the packaging and delivery of liquids, such as milk and the like, and has particular reference to such a container preferably made from paper or fibre stock having a bellows bottom construction which is pre-bent before liquid-proofing to prevent leakage of the contents through subsequent rough handling of the container. The container produced by the instant method is an improvement upon the container disclosed in United States Patent 2,085,979, issued July 6, 1937, to John M. Hothersall, on Container.

In the production of tubular containers of the Hothersall type preferably made from paper, fibre or similar stock, it has been the practice to form a rigid supporting truss portion at the open ends of a tubular container body to brace the body walls against inward and outward movement, the body wall being bent obliquely inward then horizontally outward at a relatively sharp angle and then horizontally inward in spaced relation to the horizontal outward wall to provide an end closure receiving channel and support shoulder. The top and bottom end members then are firmly secured within such a receiving channel by a thermoplastic cement or other suitable adhesive which produces a strong liquidproof joint.

Under severe handling of these containers in transporting them from the filling plant to the ultimate consumer, leaks have occurred occasionally in the bottom end joint due to the crushing of the aforementioned rigid end construction. These leaks have been attributed chiefly to the bottom end being partly separated at the base of the truss portion where the bottom end meets the outer curvature of the sharp angle between the obliquely inwardly bent portion of the body and the outer horizontal support. Such separation of the end seam under a crushing blow at the bottom joint of the container permits the liquid contents to leak past or around the bottom joint.

Occasionally the leaks have also been attributed to the breaking of the liquid-proof coating at the upper corner of the truss portion when this rigid truss portion is distorted under a severe crushing action against the bottom joint of the container. The breaking of the liquid-proof coating caused by a distortion of any portion designed to remain undistorted permits the liquid contents of the container to seep into the fibre stock and soften it so that a leak of varying proportions may eventually develop.

The instant invention contemplates overcoming these difliculties by the pre-bending of the container portions inward of the end seam portions at a definite point to form a flexible channel connection of predetermined definite shape between the container body and its end seams.

An object of the invention is to provide a fibre container for liquids wherein the end members of the container are connected to the body member by way of end seams which include a flexible connecting channel member or portion having its corners bent to a predetermined degree of sharpness, prior to coating the container with a liquid-proofing substance, so as to resist subsequent deformation of the end seams in a horizontal plane and so as to prevent the flexing or breaking of the liquid-proof coating at any location other than said predetermined locaion so that any subsequent crushing action against the end seams will have no harmful effect on the container and will thereby prevent leaks through the end seams.

Another object is the provision of a method of producing such a fibre container wherein the channel member or portion is formed in the body and its corner connections bent to a predetermined degree of sharpness prior to the liquidproofing of the container so that the liquid-proof coating thoroughly impr-egnates the pre-bent regions of the container with the result that any subsequent crushing action against the bottom of the container merely fiexes the channel member without breaking the liquid-proof coating of the channel member and the adjacent portions of the container thereby preventing leaks at such points.

Another important object of the invention is to provide a predetermined, pre-bent channel member or portion in the container which is preformed of such a shape so as to counteract the hydrostatic pressure of the contents upon it when the container is subjected to severe handling shocks, thereby counteracting the normal tendency of the container stock to resume its original shape and tending to separate the joint between the container body and end member.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

Referring to the drawings:

Figure 1 is a perspective view of a sealed container embodying the present invention and produced in accordance with the method steps of the invention;

Fig. 2 is a fragmentary enlarged vertical sectional view of the bottom end of the container shown in Fig. 1;

Fig. 3 is a perspective view of a fibre container body from which the container shown in Fig. l is made;

Fig. 4 is a fragmentary enlarged sectional view of the bottom end of the container showing the initial step of forming the channel member or portion in the body, the view also illustrating apparatus in section for effecting this step;

Fig. 5 is a view similar to Fig. 4 showing the step of and apparatus for securingan'end member to the container body;

Fig. 6 is a view similar to Fig. '4 showing the step of and apparatus for bending the corners of the channel member or portion in the container body to a predetermined degree of sharpness; and

Fig. 7 is a sectional view showing how the liquid-proof coating is applied to the container after its channel portion has been formed with its sharp corners.

As a preferred embodiment of the instant invention the drawings illustrate a fibre, rectangular shaped, milk container having a shock resistant end seam construction and a method of producing the same adapted to prevent leaking of the container. The container comprises a substantially rectangular body member ll (Figs. 1 and 2) closed at its ends with suitable top and bottom ends or closure members [2, 13. The body ll preferably is formed from a single sheet of fibrous material which is folded at right angles to provide four side walls, designated by the numeral I l. The edges of the sheet are joined along one of the side walls in an overlapped vertically disposed side seam 15. These seam edges are secured together with a suitable adhesive and a liquid-tight side seam results. Top and bottom end members I2 and I3 preferably are square and are formed of fibrous material.

For the purpose of providing flexible, leakproof end seams resistant to shocks and crushing blows, particularly at the bottom, the body marginal portions are bent inwardly, preferably at substantial right angles, resulting in a sharp annular corner I-8 (Fig. 2) and a substantially horizontal wall section IS. The -wall section l9 merges into an inwardly disposed curved 'Wall section 2| which merges into an outwardly extending horizontal wall section '22 disposed -in spaced and substantially parallel relation to the wall section I9. These wall sections 19, 22 together with their connecting curved wall section 2| set off a flexible u-shaped channel member or portion 23 extending completely around the container body adjacent one -or both of its opposite ends. The wall section 22 of this channel member forms a shoulder or supporting wall for the bottom end'member I3.

An inwardly extending securing fiange- 25, being an integral continuation of the channel wall section 22 extends down around the peripheral edge of the end member I3 and thence inwardly against the outer surface of the end member as best shown in Fig. 2 to hold the endmemberin place. As hereinbefore mentioned, a suitable liquid-proof adhesive is interposed in this'end seam joint, between the end member l3 and the channel wall section 22 and the flange 25 to provide a strong liquid-tight seam.

For best results in preparing the containerfor subsequent shocks during use, it is desirable to temporarily form the corner l8 of the channel member or portion 23 as sharp as possible and this is effected by momentarily collapsing the end of the container against this corner as shown in Fig. 6 and as will be later described. This action temporarily pre-bends the material of the body side wall and the wall section I9 of the channel member adjacent the corner into an acute angle, thus imparting to this corner a definite and permanent condition of the container fibers at this locality as would result from a crushing blow on the filled container if it had not been so p're-bent, so that after this momentary bending operation, when the bending pressure is released and the inherent flexibility of the material springs these wall sections apart to their original position (Fig. 5), a predetermined flexible sharp corner [8 of substantially right angle form will result. This flexible sharp corner of the body is thereafter impregnated with a liquid-proof substance such as waxes, parafiin or the like, as shown in Figs. 2 and '7 and the entire inner and outer surfaces of the container are coated with a layer 21 of this liquid proofing or impregnating substance to render it liquidtight.

With such a construction of end seam, any crushing blows or shocks received at the bottom of the container while in use merely flexes the channel member or portion 23 and the bent liquid-proofed corner I8 back to a shape similar to that imparted before impregnating and thus in no way injures the container, with the result that the liquid-proof coating is maintained unbroken around the pre-bent portions and leaking of the container is prevented. By this same construction the flexibility of the-channel member 23 relieves substantially the strain on the wall section 22 and the flange =25 adhesively attached to the bottom end member [3 and thus resists any deformation of the seam parts in a horizontal plane and also resists breaking of the liquid-proof coating around them with the result that separation of the seam parts and leakage of the liquid contents of the container are prevented.

The top end member l2 may be protected in the same way as the bottom member just described. However, this is not necessary ordinarilysince usually the crushing action is exerted against the bottom of the container. This top end member is equipped with a filling and dispensing opening which is sealed with a hinged closure 28 (Fig. 1) which may be the same as that disclosed in the Hothersall patent-above mentioned.

In accordance with the method steps of the invention thetubular container body H as illustrated in Fig 3 is first provided. This body morn-- ber, adjacent its'openends, carries a bando'f thermoplastic o'r'oth'er suitable adhesive 30 applied to its inner surfaces "and extending completely around the body for securing the end members I2 and I3 inplace.

The channel member 23 is formed inwardly of the marginal edge portions of the body and includes a'portion of the band 'of thermoplastic adhesive. This is accomplished by'bending the side walls M of the body inwardly as shown in 'Fig. 4. This bending operation may be efiected in any suitable manner, as for example, by means of an interior anvil or backing-up tool3l and an outside die member or jaw 32. The anvil 3| is formed with a groove33 having a contour of the shape desired to effect the formation of the channel member 23. The die 32 is likewise formed with a projection 34 of the proper shape and dimension for cooperation with the groove 33 to form the channel member 23 when the die is forced against the side wall M of the body, the body side wall being forced into the anvil groove under pressure of the moving die.

After the forming of the channel member 23 and while the flange portion 25 of the body remains in the plane of the body wall M, as shown in Fig. 4, the bottom end member I3 is inserted into the open bottom end of the body in any suitable manner and is pressed home against the supporting wall section 22 of the channel member 23. While the end member is in thisinserted position the flange 25 is bent inwardly over the end member as best shown in Fig. 5, to hold the end member in place. Where a thermoplastic adhesive is used, as is preferred in the instant case, thisadhesive is heated to a sticky condition just prior to the flangebending operation or simultaneously with this operation.

By way of example, the bending of the flange 25 into end member holding position is effected by a bending and pressing head 31 (Fig. 5) and a plurality of backing up jaws 38 of the type disclosed in Figs. 21 and 23 of United States Patent 2,200,276, issued May 14, 1940, to John M.

I-Iothersall et al. on Can End Assembling Machine.

In this mechanism the jaws 38 are formed with support projections 39 which are insertable into position adjacent the channel member 23 to back up the wall section 22 while the head 31 bends the flange 25 and compresses it against the bottom end member 13. Both the jaws and the head are movable toward and away from the container and the jaws are preferably maintained in a heated condition for heating the adhesive on the body into a sticky consistency during the end attaching operation.

The end attaching operation as just described is followed by the temporary or momentary bending ofthe portions of the container body adj acent the corner 18, about the corner as an axis and into an acute angle formation (Fig. 6). In this bending operation, the channel member 23 is flexed as shown in Fig. 6 so that the corner E8 of the body will be pre-bent as would occur during severe handling of the container or after it is filled. This bending operation bends the fibrous structure of the body material at the corner 18 and leaves them in a more flexible and somewhat softer condition than the unbent portions of the container body. However, after being bent the inherent flexibility of the fibrous stock springs the channel member back into a substantially right-angled position. This momentary bending operation may be effected in any suitable manner. By way of example such a bending is effected by a pressure pad Ill which is movable toward the end of the body for pressing the end seam against the corner 18.

Following the bending of the corner I8 of the container body, the entire container including its inner and outer surfaces are coated or impregnated with a layer 2? of a liquid-proofing substance, preferably a waxy material such as paraffin. Such an operation may be carried out in any suitable manner for example by immersing the container in a bath of hot molten parafiin d3 (Fig. '7) contained in a reservoir or tank 44. Such a method of coating containers is disclosed in United States Patent 2,153,561, issued April 11,

1939, to John M. Hothersall et al., on Coating Machine (see Fig. 2).

The application of the liquid-proofing substance to the container impregnates the region adjacent the sharply bent corner N3 of the container body to a greater extent than the rest of the body, due to the distortion and stretching of the fibers at this locality as a result of the described temporary acute angle bending operation. This impregnation of the sharply bent corner locality with the liquid-proofing substance serves to properly condition the container so that any subsequent bending of the corner as a result of handling the empty or filled container, merely causes a like bending of the liquid-proof coating without breaking the continuity of its liqdid-proofing surface, Such incidental or abnormal bending of the corner l8 into an acute angle during handling will be accompanied by a compensatory flexing of the channel member 23 with the result that any distortion of the end'seam in a horizontal plane is prevented. This action serves to prevent separation of the end seam parts and breaking of the liquid-proof coating which covers them and thus maintains the liquid-tight seal. 7

While I have mentioned the use of fibre or paper stock for making the container, the invention is equally applicable to other suitable flexible materials such as plastic or synthetic sheet material, cellophane, metal foil, etc.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the steps of the process described and their order of accomplishment Without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the procedure hereinbefore described being merely a preferred embodiment thereof.

I claim:

1. A method of producing a liquid-retaining fibre container of flexible material having a tubular body and bellows type end, which comprises bending a portion of said body adjacent an end thereof inwardly at substantially right angles to form a sharp corner at the body, and thence outwardly to form a resilient channel in said body, inserting and adhesively securing a substantially flat bottom end member into said body in engagement with the outwardly bent portion of said channel, folding and adhesively securing the terminal edges of said body around and over the marginal edges of said end member in a leakproof end seam, imparting longitudinal pressure to the container body to temporarily transform said sharp right angular corner in the body adjacent the channel into an acute angular corner to excessively bend and break down and thereby impart a subsequent permanent softened condition to the fibres of the material at said sharp corner after its return by inherent resiliency to substantial right angular configuration, whereby to provide flexibility of the corner area to yield under subsequent crushing strains, and finally coating the inner surface of the container with a liquid-proof material and simultaneously impregnating the softened flexible corner area with said liquid-proof material to a greater extent than the rest of the container, thereby providing between the bottom end member and the container body a flexible connection impregnated with liquid-proof material and capfibre container having a bellows type bottom,

which comprises providing a tubular fibre body of flexible material, bending a portion of said body adjacent the bottom end thereof inwardly at substantially right angles to form a sharp corner at the body, and thence outwardly to form a resilient channel in said body, inserting and adhesively securing a substantially fiat bottom end member into said body in engagement with the outwardly bent portion of said channel, folding and adhesively securing the terminal edges of said body around and over the marginal edges of said body around and over the marginal edges of said end member in a leak-proof end seam, pressing said end seam against said sharp corner while flexing said channel to temporarily and excessively bend the fibrous structure adjacent the corner into an acute angle to soften and break down the fibres of the material at the sharp corner to facilitate its subsequent penetration by a liquid-proof coating material and to impart flexibility to the corner material to yield against subsequent crushing blows without cracking said 8 coating material, and finally immersing said conta'iner in a bath of parainn for coating the inner and outer surfaces of the container and said end seam with said paraflin to liquid-proof said container and to impregnate the softened corner area of said channel with said paraifin to a greater extent than the rest of the container, thereby providing between the bottom end member and the container body a flexible connection impregnated with paraffin and capable of resisting distortion and separation of the seam parts and of resisting breakage of the continuity of the paraffin coating at said corners under subsequent crushing blows and strains exerted against said bottom, whereby to prevent leakage of the container contents through the corner material and through the adjacent end seam parts when the filled container is in use.

JOSEPH P. CARROLL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date -l, 0 81;583 Crowell Dec. 16, 1913 1,211,757 Reifsnyder Jan. 9, 1917 1,809,006 Wright et a1 June 9, 1931 2,089,953 Hothersa-l-l Aug. 17, 1937 2,160,072 Karl May 30, 1939 2,328,579 Pelosi Sept. '7, 1943

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