US 2930423 A
Description (OCR text may contain errors)
March 29,1960 M. M. CUNNINGHAM ETAL 2,
COLLAPSIBLE CONTAINER Filed Nov. 12, 1957 3 Sheets-Sheet 1 QW War/Z ATTORNEY March 29, 1960 M. M. CUNNINGHAM ET AL ,93
COLLAPSIBLE CONTAINER Filed Nov. 12, 1957 I5 Sheets-Sheet 2 INVENTORS MAR/0N M. C Z/IV/V/IVGHAM W/Z L/AM FRASER A TTORNEY March 1960 M. M. CUNNINGHAM ET AL 2,930,423
COLLAPSIBLE CONTAINER Filed Nov. 12, 1957 3 Sheets-Sheet 3 INVENTORS MAR/0N M C U/V/V/A/Gl/AM W/lL/AM PRAG'ER BY ATTORNEY United States Patent COLLAPSIBLE CONTAINER Marion M. Cunningham, Providence, and William Prager, Hoxsie, R.I., assignors to United States Rubber glompany, New York, N.Y., a corporation of New ersey Application November 12, 1957, Serial No. 695,961
9 Claims. (Cl. 1501) This invention relates to collapsible liquid packages or storage containers and particularly to packages or containers of this type formed by closing the ends of a flexible tube.
In the packaging industry containers are often referred to as packages. Accordingly, in this'application the terms will be used synonymously, and what is discussed with respect to a package for transportation purposes will also apply to a container for storage purposes.
A simple and inexpensive package or container may be constructed of flexible material merely by forming a tube and closing off both ends by flat clamps. If the material is a rubber or similarly coated cord fabric, the tube may be given any desired size and any desired length by vulcanizing it in a flatly pressed condition, as de scribed in United States Patent No. 2,381,074, instead of in a round condition. Such a tube would have permanent lines of fold along its opposite sides which will enable it to lie in a completely flat condition when not inflated or filled. It may thus be rolled up into a compact package when not in use, so that great savings are realized in return shipping and storing when empty.
Heretofore, containers of this type have been constructed merely by closing each end of the tube by a straight clamp. When empty, such a container collapses into a doubly covered rectangle.
This kind of construction, while having the advantages described above, disregards an important strength characteristic of the cord fabric forming the walls of the container. Whereas this fabric withstands repeated moderate bending and subsequent flattening almost indefinitely, a few repetitions of sharp bending and subsequent flattening tend to split the plies of the cord fabric and induce premature failure. When a container of the construction heretofore described is pressurized, pronounced wrinkles are observed to form in the container walls near the ends of the container. During each filling and subsequent emptying of such a container, the wall fabic is sharply bent along these wrinkles and then flattened with the consequent damage to the wall fabric as described above.
The primary object of this invention is to provide a collapsible container that has the advantages heretofore described but which, in contrast to similar containers proposed so far, is substantially wrinkle-free. in all degrees of expansion from the completely flat condition to the fully expanded condition.
In accordance with the present invention, this object is obtained by closing each end of the tube by two substantially conical extensions having their vertices laterally spaced and forming the extremities of the container. Also, in accordance with the present invention, it has been found that such substantially conical extensions may be easily formed by cutting a reentrant angle of approximately 165 and preferably between 162 and 168 in the end edges of the tube when the tube is int! 2,930,423 Patented Mar. 29, 1960 ice flattened condition and then clamping or securing the cut edges together.
When a container constructed in accordance with the present invention is pressurized, the cross section of the central portion approaches a circular form. When the container is empty, this central part collapses into a doubly covered rectangle. By virtue of the reentrant angle, each endofthe container takes the form of a pair of cones, the vertices of which are symmetrically and laterally spaced along a common diameter of the cylinder and form the extremities of the container. Each end of the tank also will collapse into a doubly covered plane without stretching, creasing or wrinkling.
Thus in the transition from the full to the empty state, the entire flexible material forming the wall of the container is bent but not appreciably stretched, creased or wrinkled. Because of the absence of pronounced wrinkles caused by pressurization, or internal loading, the container can withstand a practically unlimited number of filling and emptying cycles without damage. A flexible container constructed according to this invention will therefore have a much longer useful life than those heretofore constructed. It will be better able to withstand internal pressure and the abuses to which it is subjected by ordinary usage. I a
A container constructed according to this invention can be used for storage of gases and liquids as well as for their transportation using it as a package. It can be economically constructed in all sizes and capacities to meet individual requirements. In liquid transportation service, the roll-up package feature, making possible a return payload in space saved, will prove itself very economical. Strong tire-like construction will insure performance with safety.
By having a broad ground contact area this container can be used for storage where low unit floor loading is a requirement. Also this large footprint causes the container to be stable during braking or acceleration when used as a liquid package.
A loose interior lining may be used if the nature of the contents makes this desirable. Emptying in that case can be either by sucking the contents from an orifice in the container or by introducing air under pressure between the loose lining and the container wall to thus force the contents out.
All types of liquids and gases, including corrosive materials, can be stored and transported in this package. It is particularly well suited to viscous liquids like molasses.
This package will make any highway truck also a liquid carrier and, on railroads, any flat car or gondola car a liquid carrier. For storage it replaces the rubber-lined metal tank in that it is its own structure. p
When inflated with air, it can be used as a chock to prevent other containers from moving during transportation. Its adjustable diameter, obtained by different degrees of inflation, will make thechock fit any truck or railroad bodys unfilled width.
For a better understanding of these 'and other characteristics and advantages of the present invention, refer]- the method of sealing and a type of segmented clamp that can be used for same;
Fig. 5 is a schematic view of the general method used for closing the ends of the tube to form the container;
Fig. 6 is a detail of a segmented rotatable clamp that can be used to close the ends of our container, showing the method of running the cords of the fabric underneath the clamp, and with one of the plies broken away to show the ply underneath; and
Fig. 7 is a cross-sectional view along line 77 of Fig. 6, the solid lines indicating the container walls when empty and the dotdash lines when inflated or full.
Referring to the drawings there is shown the flexible container of this invention having a cylindrical body portion 10 and closed at the ends by a pair of cones 11 and 12 which form a reentrant angle 13 in the ends. A filling opening 14 may be disposed in one end of the container as shown. Closing fixtures consisting of segmented plates or clamps 15 grip the fabric and bind it both laterally and axially at the end portion and thus effect the closure. If only two rigid plates are used to close the ends of the container, they must be hinged together at the vertex 13 of the reentrant angle and thus cause concentrated lateral flexing. If, however, a number of clamps 15 are used to close the ends of the container, they may be disposed so as to permit individual rotation and consequent change in the reentrant angle 13 as the pressure or loading inside the container varies, as illustrated in Fig. 2.
The walls 16 of the container as shown in Fig. 3 are formed of a plurality of layers of cord fabric. Since a single layer of cord fabric has strength in the warp direction only, several plies are used to build a wall in which each ply has its warp yarns placed at a substantial angle to the warp yarns of the adjacent layers so that the wall has two-directional strength. This equal ply construction is well known in the tire industry. The inner and outer layers of cord fabric of the walls of the container may becoated with a heavy surface layer of rubber or other suitable material to protect the cord fabric against the material to be shipped or stored in the package as well as against external abrasions.
Various techniques of manufacture are possible. The container may be made by winding cord on a mandrel in a continuous helix, covering the individual cords with rubber or similar material and vulcanizing. Or rubber coated cord cord fabric may be cut on the bias of the fabric, plied up, rolled into a cylindrical shape and seamed. Curing may be in the fiat or as a cylinder.
Fig. 5 shows the basic method chosen for closing the tube 10. The axis of the cylindrical portion 10 of the container should be visualized as being horizontal. The cylindrical part 10 of the tube is bounded on the left by the circle ABC, whose plane is perpendicular to the axis. In the horizontal plane through the axis, points V and V are symmetrically situated with respect to this axis. These points are used as the vertices of two cones 11 and 12 both based on the circle ABC.
It was found that when a reentrant angle 13 of approximately 165 is cut in the ends of the flattened tube as shown by the solid line in Fig. 2 and the said ends are clamped or otherwise secured together with a hinge motion possible at the reentrant angle apex13, the two cones 11 and 12 thereby formed at theextremities of the container are so located as to result ina geometrical structure which is approximately developable. Thus, this configuration of end cones 11 and 12 gives a container which will be substantially wrinkle-free at all degrees of inflation.
The reentrant angle of 165 was found to be the optimum angle for closing the tube 10 by merely clamping the ends. This angle can be rounded off by a fillet in the actual construction of the container. 'It is recommended, for instance, that a fillet radius of approximately inches be used for a container diameter of approximately 10 feet.
As the end cones are based on the circle ABC in Fig. 5, their intersections with any plane that is perpendicular to the axis of the tank will be circular. Thus, if the vertex of one of the end cones be cut off perpendicular to the axis of the tank, this cut will form a circular filling hole 17 as shown in Fig. 4.
The design of the seams at the ends of the container must take into consideration that the reentrant angle 13, which for a container of optimum configuration is 165 in the empty condition, decreases to approximately when the tank is completely filled, as shown by the dotted line in Fig. 2. The corresponding freedom of motion can only be assured by a hinge at the reentrant corner 13. It should be understood that theoretically only two straight clamps are needed to close each end, these clamps being hinged at the reentrant corner 13. The segmented clamps 15 shown in Fig. 4 are advantageous when it is considered that the resulting structure is not rigorously developable. Rotation of these clamps 15 can compensate for the slight excesses and deficiencies of wall material 16.
Figs. 6 and 7 illustrate a type of rotatable clamp 15 that has been found satisfactory. One edge 19 is curved outwardly to avoid injuring the wall material as the container expands. The cords of the material forming the container walls run under several of the clamps 15, as shown in Fig. 6, thereby effecting a secure closure. Although two straight clamps broken at the apex of the reentrant angle 13 are necessary, if it should prove impossible to design a hinge which maintains a tight seal while allowing the necessary rotation, the bending theoretically localized at the corner 13might be distributed over a greater length by rounding out this corner more generously. In any case, the width of the clamp 15 at the end should be reduced to a minimum to avoid crinkling at the outer edge of the seam.
A loose lining 18 as shown in Fig. 3 may be used with this container if the nature of the contents makes this desirable. Its position 18a when partially emptied is also indicated in Fig. 3. The emptying can be effected either by sucking the contents out through the opening 14 or by introducing air under pressure through opening 14:: to force the contents out.
From the foregoing it is apparent that we have devised a storage or shipping package which has a good practical construction, in that it may be handled, stored and return shipped easily, yet which will give greatly improved wearing qualities and should have a very long life in use. In particular, this container may be made substantially cylindrical in shape, yet free of compressive stresses and the resulting wrinkles. These advantages are achieved by abandoning the tube with a straight closed end and substituting in its place the reentrant angle of the present invention.
Although a specific embodiment of a container according to this invention has been described, it is our intention to cover all changes and modifications of the example of the invention herein chosen for purposes of the disclosure, which donot constitute departures from the spirit and scope of the invention.
Specifically, although in the description of this structurea rubberized cord fabric is described, it will be appreciated that the walls of the'container may be madeup of any flexible material, and that'a container according to this invention could be made irrespective of the number of plies of the material forming its walls.
Also, although it has been found that is the optimum size for the reentrant angle, variations in this angle will not constitute a departure from the spirit and scope of the invention.
Having thus described our invention, what we claim and desire to protect by Letters Patent is:
1. 'A collapsible'container formed of relatively flexible material comprising a substantially cylindrical body portion, the opposite halves of the marginal edges of each end of said cylindrical body portion being provided with reentrant angles, said opposite halves of said marginal edges being secured together to close each end of said container., 7 v
2. A collapsible container as defined in claim 1 in which said container is of tubular form and said reentrant angles are approximately 165 when the said container is in a flattened condition.
3. A collapsible container as defined in claim 1 in which said halves of said marginal edges are secured together by rigid clamping means, said rigid clamping means being hinged together at least at the apex of said reentrant angle.
4. A collapsible container as defined in claim 3 in which said rigid clamping means form a reentrant angle of between 162 and 168 when the said container is in a flattened condition.
5. A collapsible container as defined in claim 1 in which said halves of said marginal edges are secured together by a plurality of rotatable clamps.
6. A collapsible container as defined in claim 5 in which said marginal edges form a reentrant angle of between 162 and 168 when the said container is in a flattened condition.
7. A collapsible container formed of relatively flexible material, said container having a substantially cylindrical body portion closed at each end by a pair of substantially conical extensions, the vertices of said conical extensions being laterally spaced along a common diameter of said cylindrical body portion and forming the axial extremities of said container, whereby said container is substantially developable and will be substantially free of wrinkles at all degrees of inflation, a loose liner in said container, an opening through said liner and container for filling and emptying said container, and a second opening through said container spaced fromsaid first opening for introducing gas under pressure between the wall of said container and said liner, tocjcollapse said liner and force the contents of said liner out of said first opening.
8. A collapsible container formed of a coated cord fabric, said container having a substantially cylindrical body portion closed at each end bya pair of substantially conical extensions, the vertices of said conical extensions being laterally spaced along a common diameter of said cylindrical body portion and forming the axial extremities of 'said container, whereby said container is substantially developable and will be substantially free of wrinkles at all degrees of inflation.
9. A collapsible container formed of a plurality of layers of coated cord fabric, wherein the cords of one layer form an angle with the cords of adjacent layers, said container having a substantiallyjcylindrical body portion closed at each end by a pair of substantially conical extensions, the vertices of said conical extensions being laterally spaced along a common diameter of said cylindrical body portion and forming the axial extremities of said container, whereby said container is substantially developable and will be substantially free of wrinkles at all degrees of inflation.
References Cited in the file of this patent UNITED STATES PATENTS