US2673024A - Flat bottomed tubular container - Google Patents

Description

March 1954 uss FLAT BOTTOMED TUBULAR CONTAINER 2 Sheets-Sheet 1 Filed June 11, 1951 I l I INVENTOR." Raw/2 L/fuss I IE 'zwwx A TTOANE xs March 23, 1954 R. 1.. Kuss 2,673,024

FLAT BOTTOMED TUBULAR CONTAINER Filed June 11, 1951 2 Sheets-Sheet 2 F1512. E r E15.

7 I/IIl/ q1i572 V R w/7 1.. H055 BY Cam) x Law) A T TORNEYS Patented Mar. 23, 1954 UNITED STATES PATENT OFFICE 7 2,673,024 FLAT BOTTOMED TUBULAR CONTAINER Ralph L. Kuss, Findlay, Ohio Application June 11, 1951, Serial No. 230,960

1 Claim. 1

. This invention relates to a" flat bottomed tubular article and to a method of making same. More particularly, this invention is directed to a method of producing a flat bottomed tubular bag or liner from sheet material.

Heretofore barrels, steel drums and glass botties or carboys have been employed in the transportation of liquids and solids. Since containers of this type are cuite expensive in additionto adding considerable tare weight to the cost of transportation, much research has been directed to the development of cheaper and lighter containers. The use of liners within permanent containers made of fibre has been proposed, but injury to these liners frequently occurs either during loading or transportation. I

In' loading liquids using the fast-loading apparatus now in common use, the liquid has the effect of a hydraulic ram forcing the liner rapidly against thesides of the supporting containers. Since practically all liners are of the envelope type coming to a point at th bottom, the sudden hydraulic pressure against edges of the liner envelope frequently causes breakage thereof.

Furthermore, doming of the container during transportation puts an additional strain upon the liner which frequently results in failure thereof. To be practical, therefore, a liner must be economically produced both from a standpoint of labor and material, and must b fluid tight. In addition, the liner must be so constructed as to withstand sudden large pressures along the bottom border adjacent the chimes of the supporting container. This same set of requirements is equally applicable to self-supporting bags or the like.

It is an object of this invention, therefore, to provide tubular, flat bottomed articles so formed as to provide maximum strength along the bottom border thereof.

Another object of this invention is to provide a method of fabricating from sheet or web material a tubular article having a polygon crosssection and a flat bottom, the corners of which are puckered to provide excess material.

Afurther object of this invention i to providea tubular article having a flat bottom produced'by sealing together at adjacent marginal portions a plurality of segments which are so shaped that no more than two seals intersect at any given point and the outer ends of the seals or corners of the bottom contain excess material. e

Other objects and advantages of the present invention will become apparent from the following detailed description thereof, when read in conjunction with the accompanying drawings, in which Fig. 1 is a plan view of a web for use inmaking one form of article embodying the present invention,

Fig. 2 is a plan view of the web shown in Fig. 1

folded back upon itself and marginally sealed 7 along one edge,

Fig. 3 is a perspective view of the sealed web of Fig. 2 opened into tubular formation for purposes of illustration,

Fig. 4 is a plan view showing the tubular body of Fig. 3 again flattened as in Fig. 2 and with the outsid adjacent marginal portions of its triangular projections sealed together,

Fig. 5 is a plan view of the tube of Fig. 3 after being refolded forming the positions shown in Figs. 2 and 4 to permit a single straight continuous seal diagonally across the bottom thereof, Fig. 6 is a perspective view of the completed article of Fig. 5 in inverted position illustrating the novel type of flat bottom resulting from the sealing operations,

Fig. 7 is a plan view of the bottom of the article shown in Fig. 6,

Fig. 8 is a plan view of a hexagonally shaped tubular article embodying the present invention and Fig. 9 is a perspective View of the same article,

Fig. 10 is a plan view of a web for use in producing the article shown in Fig. 9,

Fig, 11 is an enlarged fragmentary view of a bottom corner of an article produced in accordance with the present invention,

Fig. 12 is a plan View of the bottom of a square tubular article showing in exaggerated proportions the effect of undersized segments composing the bottom of the bag,

Fig. 13 is an enlarged section taken on line I3-l 3 of Fig. 12,

Fig, 14 is a magnified plan view of the indicated section of Fig. 12,

Fig. 15 shows a liner produced in accordance with th present invention and mounted within a supporting container,

Fig. 16 is an enlarged fragmentary section taken on line l6l6 of Fig. 15,

Fig. 17 is a companion View to Fig. 16 showing the effect of doming during transportation,

Fig. 18 is'an enlarged fragmentary view illustrating how the ends of the projections can be rounded in order to facilitate the cutting of successive liners from a single piece of material,

Fig. 19 is a view similar to Fig. 12 but showing a reinforcing means applied to the intersections of the bottom seams,

- Fig. 20 is a view similar to Fig. 8 but showing the application of reinforcing means as' in Fig. 19,

Fig. 21 is a greatly enlarged fragmentary view of one of the seam intersecting reinforcing means taken from the inside of a container,

Fig. 22 is a fragmentary sectional view taken substantially on the line 22-42 of Fig. 21.

It has been discovered that a fiat bottomed tubular article having improved characteristics may be produced from a sheet or web by forming projections along one side of the web which, when positioned in edge to edge relationship, form a flat polygon. The adjacent marginal portions of these projections are then sealed along a ,line spaced inwardly from the edge thereofso as to cause a pocketing of the bottom. corners of thearticle. These: projections are also formed in such a manner that no more than two seals intersect at any given point.

In order to illustrate the practice of the present invention in regard to the production of a tubular body having a square cross-section, for example, reference is made to the accompanying drawings wherein Fig. l discloses a plan view of a web 28 having projections 2|, 22, 23 and 24 formed along one edge thereof. To form the tubular body, the web is folded back upon itself in the manner shown in Fig. 2 and sealed along the edge 25. As shown in Fig. 3, a tube is thereby formed having a square cross-section. After the seal 25' has been made, edges 26 and 29 are superimposed. over edges 33 and Eli], respectively, and seals 34 and 35 are made. The tube is then opened and refolded with the seal 25 running down the middle of the front, as shown in Fig. 5. By pushing the seal 34 backwardly so that it at least partially overlays the seal the remaining unsealed portions of the marginal projections fall into a continuous straight line and are sealed by a single continuous seal 36.

Since the invention is primarily directed to the bottom structure of the article, the projections formed along the one edge of the Web and the manner in which these projections are sealed together will be described in considerably more detail. Projections 2i to 24, inclusive, are each triangular and, when combined in edge to edge relationship, as shown in Fig. 7, produce a flat square bottom. Projections 2i and 22 identical to projections 23 and 24, respectively, and are so formed that edges 26 and 33, as well as adjacent edges 28 and 39, are of equal length. Thus, when the web 529 is folded back upon itself and the sides sealed as at 225, projections 21 and 22 overlay projections 24 and 23, respectively, so that edges 26 and 33 are adjacent one another. Although of the same length, edge 26 extends from web 20 at a different angle than edge 33. To superimpose these edges it is necessary to move the edge forwardly, causing an outward bulging of the upper layer of the web 20. Edges 29 and Bil are similarly related, so that superimposition of these edges causes bulging of the lower layer of the web 20. Upon sealing these respective edges to produce seals 34 and 35, the middle of the tubular body is slightly spread, as shown in Fig. 4. After making the seals 34 and 35, the tubular body is folded flat with the seal 25 in the middle of the upper layer, as shown in Fig. 5. Seal 34 is folded inwardly so that the corner for; ed at the outer end thereof is fitted into the corner formed at the outer end of seal 35. In this position edges 2'! and 32, as well as edges 23 and ti, fall into a straight line with the former two edges superimposed upon the latter two edges. The final seal 36 is straight and continuous, forming a diagonal across the bottom of the article, as shown in Figs. 6 and '7.

All seals are made along a line spaced inwardly from the edge of the projection. Since the projections are cut so as to form a polygon in edgeto-edge formation, this reduction of material caused by the sealing operation draws the bottom inwardly and puckers the corners, as shown in Figs. 11 and 12, Furthermore, no more than two seals intersect at any one point. The importance of these features is subsequently discussed. It will also be noted that edges 26 and cent marginal portions of equal length. The advantage of first sealing these; edges together, as described, will be immediately apparent from the plan view of Fig. 7.

Although the invention has, up to this point, been described in connection with the production of a tubular article having a square crosssection. and square bottom, it is equally applicable to other articles having a polygon cross-sect'ion, such as. ahexagon. As shown in Fig. 8 projections 38, 39, M and 42 are triangular in shape and combine with the projections M) and 43 in edge-to-edge relationship to produce a fiat hexagon. Projections'38, 39 and 40 are identical in shape with 4|, 42 and 43, so that these projections may be divided into two groups each of which provides one half of the bottom of the tubular article. A web for producing this hexagonal article is shown in Fig. 10. The web is sealed at M, shown in Fig. 8, between projections 39 and 40, since the shortest, adjacent, coextensive marginal portions of any of the projections are between projections and and 42 and 43. These shortest adjacent marginal portions are sealed first, so that projections 39 and 4!} as well as projections 2 and 43 may be sealed to one another without first reforming or refolding the tubular member after the seal M has been made. Numbering these first seals 45 and 46, the next two seals to be made are indicated as 41 and 4B. Projections 38, 39 and 40 are thus sealed to one another to produce onehalf of the bottom of the article and projections A! 42 and :33 are sealed to one another to produce the other half of the bottom of the article. Consequently, a single diagonal seal 49 joins these two halves to produce the finished article shown In order to illustrate the advantages or" the present invention, a bottom corner of a tubular article produced in accordance with this invention is shown in Fig. 11 and illustrates the puckered formation of the corner. The edge of the projection is shown at 50, the seal is shown in dotted lines at 5| and the interior surface indicated at 52. The side of the article is curved outwardly, as shown at 54, so that excess material is present in each of the corners. A plan view of a square bottomed bag is shown in Fig. further illustrating the puckered formation of applicants article.

The advantage of this particular puckered corner becomes particularly apparent when the article produced is a liner, such a 55, to be used in conjunction with a supporting container 5% As shown in Fig. 16, the excess material in the corners forms wrinkles 57, so that the pressure exerted by fluid or other means against the interior of the liner cannot possibly put the relatively thin liner material under tension or stress of any kind. Even when doming occurs during transportation, as shown in Figure 17, the liner 55 is still under no stress due to the excess ma terial present in the corners.

In the above description of the invention, the fact has been stressed that no more than two seals intersect upon the bottom at any given point. Figure 13 shows a cross-section of a single seal, wherein the sealed portions form a raised ridge along the bottom. When one seal intersects another, as is shown in Fig. 14, one of the seals must :be folded over, as shown at 53, and it is this folded-over portion which creates the difficult sealing problem, At the junction of the three sheets of material represented by edges 59, ESQ and SI, a void 62 is formed. Sufficient pressure upon the folded over portion 58 will close this void, but there still exists the problem of exciting sufficient pressure to unite the edges 59 and 98 to the edge 6| without unduly stressing the portion 58. Particularly vulnerable spots are low pressure points 63 and 64-. This problem can be solved where there are only four thicknesses of sheet material and one reverse fold (of edge 60), as shown in Fig. 14. When three sea s intersect, however, the sealing apparatus employed must simultaneously seal two thicknesses of sheet material together and siX thicknesses of sheet material at the point of intersection. Furthermore, two reverse folds are involved as we l as two voids. so that it is pract cally impossible to obtain uniformlv tight seals where three or more seals intersect. For this reason. it is an important feature of this invention to so form the pro ections that no more than two seals intersect at any given point on the bottom of the article.

It has been found desirable to round oil the apices and vallevs of the projections in the manner shown in Fi 18 in order to facil tate c t in of the proiections to avoid tears and to out down on the waste material between adjacent liners cut from the basic material. As is seen in Fig. 18 Liner A and Liner B which desi nate two separate liners can be cut with ease from the material with relatively, little loss by interdigita-ting the projections on each.

While it is generally true that forming container liners havin flat bottoms in the manner of this invention so that no more than two sea-ms intersect at any one point. provides l ner: of more than suffic ent strength to withstand violent a itation dur n fillin and shipping. yet under some circumstances it may be desirable further to reinforce the seam intersections. In Fi s. 19 and 20 there is i lustrated the addition of re n orcing buttons 65 which are heat sealed in place over the intersections between the seams connecting the triangular or enerally trian ular pro ections which form the bottoms of liners embodying the invention. As can be seen in these two fi ures a button of material, probably identical with that from which the liners are formed. is heat sealed directl over each seam intersection.

In Fig. 21, which is taken from the interior of a liner embodying the invention. a generally circular button 65 is shown as applied directly over intersecting seams 36 and 34 as formed on a souare bottomed liner such as is shown in Fi s. '7, 12 and 19. The button 55 is sealed flat over the actual point of intersection between the two seams. thus providing reinforcing strength on and over their overlapped portions as at the folded over portion 58 shown in Fig. 14 and in Fig. 21.

In Fig. 22 it can be seen how the seam 35 overlaps with the seam 34 to form a thickened section of material. The button 65, by extending'laterally of the overlap edportions of the two seams, not only more tightly seals the seams but also transfers the forces tending to open the seams to the body portion of the liner.

Numerous modifications and variations of the present invention as hereinabove set forth will become apparent to those skilled in the art. The invention is not limitedof course to the square or hexagonally shaped articles shown in the drawings, but applies equally well to tubular articles having any one of the many possibly polygonal cross-sections. Nor is the invention limited to the particular shape of projections shown in Figs. '7 and 8, since differentlyrshaped projections will be readily apparent to those skilled in the art which can be so combined that no more than two seals intersect at any given point. While the projections have been described as triangular in shape, it will be apparent, particularly from Fig. 8, that these projections may be four-sided as well as three-sided. A modified triangular shape is also shown in Fig. 18. The term triangular projections, as employed in the specification and in the claims hereinafter set forth, is intended to cover all projections which approximate the triangular shape, such as 49, 43 and the projection shown in Figure 18. In the preferred form of the invention, the shortest adjacent coextensive marginal portions of the triangular projections are sealed first, and the remaining unsealed marginal portions are sealed in the order of increasing length, since this procedure provides the simplest and quickest method of fabrication that has been devised. The longer edges may in certain modifications be sealed first, although this does not constitute the preferred form of the invention. The particular type of seal employed is not pertinent to the present invention, but this invention is particularly adaptable to the production of tubular articles from heat scalable plastic materials. Other types of materials may, of course, be employed.

The invention not only contemplates the modification of its particular features which are set forth above but it also contemplates modifications in reinforcing and lapping procedures such as may be improvised in accordance with the illustrations given. The principal objective in any modification of the instant invention is achieved by carrying out the practice of forming a fiat container bottom from a plurality of projections formed on its sides and folded over with their margins sealed in edge-to-edge relationship and the projections being so shaped as to form a closed bottom without more than two of the edge seams intersecting at any given point.

Having described my invention, I claim:

A fluid-tight generally tubular container having a fiat bottom and comprising a sheet of material folded upon itself and sealed marginally thus forming a tubular structure, the lower edge of said sheet of material being serrated with pairs of irregular two and three sided projections, the projections in each pair being identical and having at least one projection of a different shape located between said pair of projections, the adjacent edges of a projection in one pair of projections and the intervening projection having the same length, the adjacent edges of each two of said projections being sealed together along lines spaced inwardly from the edges thereof, all of said projections when in edge to edge sealed relationship forming a fiat polygon with not more than two of the sealed edges intersecting at any one point.

RALPH L. KUSS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,160,488 Ringler May 30, 1939 2,189,174 Hohl Feb. 6, 1940 2,265,075 Knuetter Dec. 2, 1941 2,432,122 Pardee Dec. 9, 1947 2,438,981 Waters Apr. 6, 1948 2483,162 Vivian Sept. 27, 1949 2,516,820 Wilson July 25, 1950

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