[0001] This application claims the benefit of U.S. Provisional Patent Application No. 60/650,793, filed on February 8, 2005.

Field of Invention

[0002] The present invention relates to a plug for an opening of a container, and in particular to an end-plug for a shipping tube or the like.

Background of Invention

[0003] Shipping tubes are known for shipping long narrow objects, including rolled up sheets. One form of shipping tube consists of a tube of cardboard or fiberboard that is closed at each end by a plastic plug inserted into the tube. The tube may be cylindrical or some other shape. The plug is typically in the form of a shallow dish, with a wall that fits the inside of the tube and is cylindrical or otherwise corresponds to the shape of the tube, with a lip that abuts the end of the tube, and with a flat bottom. This sort of plug is held in place by friction between the tube and the wall of the plug.

[0004] However, the frictional force impedes insertion as well as removal of the plug. In order for the plug not to be too difficult to insert, the frictional force is limited. As a result, the plug may be dislodged by the contents moving around in shipping, and provides no security against unauthorized removal. Other measures are therefore taken to secure the end plugs. For example, a strip of adhesive tape may be placed across the end plug, and stuck down to the material of the tube on both sides, or staples may be driven through the walls of the tube and the end plug. However, these and similar measures are unsightly, and require additional operations to secure the end plug after the plug has been inserted in the tube. In addition, it is not very difficult to cut away the tape, or pry out the staples, remove and replace the end plug, and reseal the tube in a way that is not easy to detect.

Summary of Invention

[0005] One embodiment of the present invention provides a plug for insertion into an opening of a container, comprising at least one line of weakness in a wall of the plug, the plug being so arranged that a force exerted on the plug in a direction to remove the plug from the opening can cause the wall to fail along the at least one line of weakness, and that after failure of the line of weakness at least a part of the plug is removable from said opening.

[0006] Another embodiment of the present invention provides a plug for insertion into an opening of a container, having a surface extending in a direction of insertion, ribs projecting from the said surface transverse to the direction of insertion, the ribs being arranged to engage a container opening to present less resistance to insertion of the plug into the container opening than to removal of the plug from the container opening.

[0007] The container may be a shipping tube, and the opening may then be an end of the tube.

[0008] Another embodiment of the present invention provides a combination of a shipping tube and at least one end plug for an open end of said shipping tube, comprising the plug having a wall extending in a direction of insertion of the plug into the end of the tube, ribs projecting from the said wall of the plug transverse to the direction of insertion, the ribs tending to deflect as the plug is inserted into the tube and act as barbs resisting removal of the plug from the tube, whereby the force required to remove the plug from the opening is substantially greater than the force required to insert the plug in the opening, the plug having a handle, the plug having at least one line of weakness, wherein when a force is applied to the handle to remove the plug from the tube the plug tends to fail at the at least one line of weakness before the ribs release from the tube.

Brief Description of the Drawings

[0009] For the purpose of illustrating the invention, there are shown in the drawings various forms which are presently disclosed; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities particularly shown.

[0010] Figure 1 is an isometric side view of an embodiment of a shipping tube having end plugs inserted therein.

[0011] Figure 2 is a top isometric view of one of the end plugs seen in Figure 1.

[0012] Figure 3 is a top plan view of the plug shown in Figure 1.

[0013] Figure 4 is a bottom plan view of the plug shown in Figure 1.

[0014] Figure 5 is a cross-sectional side view of an alternative form of a rib forming part of the end plug shown in Figures 1 to 4.

[0015] Figure 6 is a cross-sectional side view of another alternative form of a rib forming part of the end plug shown in Figures 1 to 4.

[0016] Figure 7 is a cross-sectional side view of a further alternative form of a rib forming part of the end plug shown in Figures 1 to 4.

[0017] Figure 8 is a cross-sectional side view of another form of a rib forming part of the end plug shown in Figures 1 to 4.

[0018] Figure 9 is a top isometric view of an alternative embodiment of end plug.

[0019] Figure 10 is a top isometric view of another alternative embodiment of end plug.

[0020] Figure 11 is a top isometric view of another alternative embodiment of the end plug.

[0021] Figure 12 is a top isometric view of the detail 12 in Figure 11.

[0022] Figure 13 is a top isometric view similar to Figure 12, showing an alternative embodiment of the ribs of the plug.

Detailed Description of the Drawings

[0023] In the drawings, where like elements are identified by like numerals, and initially referring to Figure 1, there is shown an embodiment of a container with a plug which, as shown in Figure 1, is a shipping tube with end plugs in accordance with an embodiment of the present invention. One form of a shipping tube assembly, identified generally by the numeral 10, comprises a tube 12, with an end plug 14 inserted into each end. The tube 12 may be made of any suitable reasonably rigid material. The tube 12 is preferably made of cardboard, fiberboard, or similar material. As shown in Figure 1, the tube 12 is of generally triangular profile, with rounded corners. However, the tube 12 may be of almost any geometrical shape.

[0024] Referring now also to Figures 2 to 4, each end plug 14 comprises a generally flat floor 16 and a wall 18 upstanding from the periphery of the floor 16. A lip 20 runs round the top of the wall 18. In the embodiment shown in Figures 1 to 4, the end plug 14 is generally triangular, to correspond to the triangular profile of the tube 12. If the tube 12 is of a different shape, the end plug 14 may be of a correspondingly different shape. The end plug 14 may be made from any material having suitable strength and rigidity, and which lends itself to providing a line of weakness, and is preferably molded from plastic material. High- density polyethylene, low density polyethylene, or polypropylene are examples of suitable materials. When the end plug 14 is inserted in the tube 12, the wall 18 fits inside the tube, with the lip 20 resting on the end of the tube. The floor 16 spans and closes the tube within the wall 18. The lip 20 is shaped so that its outer edge is substantially flush with the outside of the tube 12 when the end plug 14 is inserted in the tube. The straight sides 22 of the wall 18 are then in contact with the inside of the tube 12, so that the floor 16 supports and stiffens the tube.

[0025] At each corner, the wall 18 is rounded off in a curved surface 24 that is spaced inward from the corresponding corner of the tube 12. As may be seen in Figure 3, the curved surface 24 is not perpendicular to the floor 16, but is sloped so that the curved surface is further from the tube 12 at the floor than at the lip 20. A number of ribs 26, three in Figure 2, project from the curved surface 24. The ribs 26 are parallel to the floor 16. As may be seen in Figure 4, in

the unstressed condition when the end plug 14 is not inserted in the tube 12, the ribs 26 project beyond the line of the straight sides 22 of the wall 18.

[0026] When the end plug 14 is inserted in the tube 12, the ribs 26 are deflected by the end of the tube 12, so that they become angled, with their outer edges nearer to the end of the tube than their roots. If the end plug 14 is then forced outward, for example, in an attempt to remove it from the tube, or as a result of the contents of the shipping tube 10 moving within the tube and striking the inside of the floor 16, the ends of the ribs 26 tend to dig into the inside of the tube 12 like barbs, resisting removal. The material, and the dimensions, of the ribs 26 are selected so that the ribs 26 are sufficiently flexible to deflect as the end plug 14 is inserted in the tube 12, but sufficiently rigid to resist outward movement of the end plug. The material of the tube 12 is selected to be sufficiently soft that the ends of the ribs 26 dig into the tube for a more secure grip and, if the end plug 14 is removed by force, the ribs tear the tube and cause visible damage. The end of the tube 12 can thus be closed in a single operation, using only the single piece end plug 14. No additional components, and no additional assembly operations, are used. Separate external fasteners, staples, tape, or the like are needed neither for reliable closure against accidental opening nor as a precaution against tampering.

[0027] Because the curved surface 24 is sloped, the ribs 26 are of different widths from root to tip, with the widest rib nearest the floor 16. Consequently, the thicknesses of the ribs 26 may be different to give the ribs the same effect as barbs. Alternatively, the ribs 26 may be constructed to have different effects, to give the end plug 14 as a whole more tolerance for variation in the size and/or material of the tube 12.

[0028] The end plug 14 is provided with a handle 28. One end of the handle 28 is connected to the middle of one of the straight sides 22 at the lip 18, and the other end of the handle is connected to the floor 16. The handle is substantially flush with the lip 20 for most of its length, and does not project significantly beyond the plane of the lip 20. Two lines of weakness in the form of scores or grooves 30 are formed in the end plug 14, connecting the ends of the handle on each side of the handle. The spacing between the scores 30 is roughly constant along their length. At one end, the scores 30 extend to the outer edge of the lip 20. For ease of molding and pleasing appearance, the scores 30 are formed in the outer side of the

lip 20, the side that is exposed when the end plug 14 is inserted in the tube 12, and in the inner side of the wall 18 and the floor 16, the side that is hidden when the end plug is inserted in the tube. The scores 30 are arranged to weaken the material of the end plug 14 sufficiently that, if an attempt is made to remove the end plug 14 from the tube 12 by pulling on the handle 28, the scores 30 will tear before any other part of the shipping tube 10 fails.

[0029] The separation of one or both of the scores 30 allows the corners of the end plug 14 to move together, narrowing the gap left by tearing out the strip 32 of plastic between the scores or allowing the strip to overlap adjoining parts of the end plug. This reduces the engagement of the ribs 26 with the tube 12, facilitating removal of the end plug 14 from the tube. If the ribs 26 remain firmly engaged with the tube 12, then the end plug 14 can be removed by bending outward the parts adjacent to the strip 32. Whatever method of removal is used, the torn score 30 cannot be easily concealed or repaired. If the damaged end plug 14 is replaced, it is evident that it has been removed and replaced.

[0030] Thus, opening the shipping tube 10 by removing the end plug 14 from the tube 12 can be made easy for the end user who pulls the handle 28 and tears out the strip 32, while removing the end plug 14 without doing conspicuous damage can be made difficult.

[0031] Referring now to Figure 5, one form of the ribs 26, denoted 26A, has an asymmetrical cross section, with a sharp edge 40 on the side towards the lip 20 and a rounded edge on the side towards the floor 16. The rounded edge 42 helps the rib 26A slide into the tube 12, and the sharp edge 40 helps the rib dig into the tube 12 to resist removal.

[0032] Referring to Figure 6, another form of rib 26B is tapered so that the face 44 of the rib towards the lip 20 is square to the length of the tube 12 and the face 46 towards the floor 16 is angled. The effect is similar to that of the sharp and rounded edges 40 and 42. As shown in Figure 6, the angled face 46 gives the rib 26B a triangular profile. However, the angled face 46 could extend over only part of the thickness and/or only part of the width of the rib 26B, giving a trapezoidal or pentagonal profile.

[0033] Referring to Figure 7, another form of rib 26C has a recess 48 along the root of the rib on the side towards the lip 20, to help the rib bend as the end plug 14 is inserted into the tube

12. The opposite side 49 of the rib 26C is continuous, to support and transmit compressive forces as the rib 26C acts as a barb.

[0034] Referring to Figure 8, another form of rib 26D has a pointed tip 50. The chamfered underside of the point, like the angled underside 46 in Figure 6, helps the rib slide into the tube 12, and the point 50 helps the rib dig into the tube 12 to resist removal.

[0035] The features of two or more of the ribs 26A, 26B, 26C, 26D may be combined in a single rib 26.

[0036] Referring now to Figure 9, another embodiment of end plug 64 is similar to the end plug 14 shown in Figures 1 through 4, except that instead of the handle 28 the end plug 64 has a handle in the form of a pull ring 66 attached via a lug 68 to the floor 16, near one corner. A single groove or score 72 extends round the floor 16 close to the join between the floor 70 and the wall 18. When a user attempts to open the shipping tube 10 by pulling on the ring 66, the entire floor 70 tears out, leaving the tube 12 with an open end. The wall 18 remains in place, forming in effect a collar or lining round the inside of the open end of the tube.

[0037] As shown in Figure 1, the shipping tube assembly 10 has identical end caps 14 at both ends. However, it may be preferred to encourage the recipient to open the shipping tube at one end rather than the other. For example, if the content of the tube assembly is an object such as a tool that has a head at one end and a handle at the other, the sender may wish the recipient to open the shipping tube assembly 10 at the end with the handle of the tool. For this purpose, an end plug 14, 64, with a handle 28, 66, and scores 32, 72 may be inserted in one end of the tube 12 and a similar end plug without a handle may be inserted in the other end of the tube 12.

[0038] Referring now to Figure 10, a further embodiment of end plug 74 is similar to the end plug 14 shown in Figure 1 and the end plug 64 shown in Figure 9, except that the end plug 74 has no handle, no scores or other deliberate weaknesses. The end plug 74 may be inserted into the tube 12 in the same way as an end plug 14, but there is no easy way of removing the end plug 74. If the end plug 74 is removed, visible damage to the end plug, the tube 12, or

both is likely to result. Thus, if a tube 12 is provided with an end plug 14 or 64 in one end and an end plug 74 in the other end, a legitimate recipient is led to open the tube at an end chosen by the sender by removing the end plug 14 or 64, while an unauthorized recipient cannot readily open the tube at either end without leaving visible evidence of tampering.

[0039] Referring to Figure 11-13, another embodiment of the plug 14 is illustrated. Referring specifically to Figure 11, this embodiment of the plug 14 includes a handle 76 that is attached at both ends 78, 80 to the floor 16. Such a handle 76 may be used with a plug having a line of weakness 30 (Figure 4) extending between the ends 78, 80 of the handle, or a plug having a line of weakness 72 (Figure 9) extending around the floor 16. Additionally, referring to Figures 12-13, the ribs 82 extending from each of the curved surfaces 24 are vertical. The vertical ribs 82 may include an angled surface 84 to aid insertion of the plug 14 into the tube 12, and an edge 86 that is substantially parallel to the direction of insertion, for engaging the sides of the tube 12. The ribs 82 may optionally include a slot 88 defined therein as shown in Figure 13. The slot 88 extends into each rib 82 at a downward angle, so that a barb 90 is formed on one edge of the slot 88. The barb 90 is oriented at an angle that is acute with respect to the direction of insertion, so that the ribs 82 facilitate insertion of the plug 14 into the tube 12, but resist removal of the plug. Any of the embodiments of Figures 1-10 may be modified to include the ribs 82 within the scope of the invention.

[0040] Although specific embodiments have been described, various modifications may be made without departing from the scope and spirit of the invention as defined by the appended claims. For example, although the described embodiments have generally triangular tubes 12, and correspondingly triangular end plugs 14, 64, 74, other shapes may be used. A circular tube is possible, but is presently less favored than polygonal shapes for many purposes, because circular tubes are not easy to handle in shipping, as they do not stack well and may roll around. Also, a circular tube allows the end plugs to be rotated, which may allow the end plug to be removed by an unscrewing motion without tearing the tear strip. The shape of the tube 12 is not limited to simple geometrical shapes. For example, a package for merchandise of a specific shape may comprise a short tube with a shape that follows closely the silhouette of the merchandise, and two end caps that follow the shape of the tube. If the merchandise is, for example, a pair of headphones, the shape may be quite complex.

[0041] Although molded plastic end plugs 14 and a cardboard or similar tube 12 have been described, other materials may be used. However, for the configuration shown in the embodiments, the ribs are sufficiently flexible to deflect when the plug is inserted in the tube, and sufficiently rigid to resist buckling if the plug is forced outwards. The tube 12 is sufficiently soft that the ribs dig into the material of the tube and visibly damage the tube if the end plug 14 is forced outwards.

[0042] The shapes and sizes of the various components may vary depending on the materials used for the shipping tube 10, on the size of the shipping tube, and on the properties of the intended contents. For example, if components are described as straight or parallel, and are made of molded plastic, those components may in practice be tapered by several degrees for easier demolding. For example, where components are described as "triangular" or "polygonal," geometrical perfection is not required. Those skilled in the art will understand how close an approximation to a triangle is either necessary or reasonable given the intended function of a specific container and the economics of producing what is in most cases a disposable container.

[0043] As shown in Figure 1, identical end plugs 14 are inserted into both ends of a tube 12. Alternatively, as explained above with reference to Figure 9, different end plugs may be inserted in the two ends of a tube 12. Other shapes of end plug could be used. For example, one or both of the end plugs 14, 64, 74 may be provided with a fitment to assist in automated handling of the shipping tube 10. If such a fitment is provided in an end plug such as the end plug 74 without a handle 28, 66, the fitment may be designed so that it does not look like a handle and does not provide a grip that would facilitate removal of the end plug 74. Alternatively, the end of the tube 12 that does not have an end plug 14, 64 could have a different form of closure.

[0044] Although the end plug 14, 64, 74 has been described as used in combination with a shipping tube 12, the plug may be used with other forms of container, provided that the container has an opening into which the plug 14 can be inserted and can engage securely. For example, as suggested above, the tube 12 could be shorter between the end plugs than across them. For example, an end plug could form one side of a cuboidal box, or could form one end of a barrel, or could form a bung for an outlet in a barrel.

[0045] Although specific examples of handles 28, 66 have been described, it will be understood that other forms of handle are possible. The handle may be of any shape that allows the recipient of the container 10 to apply a force to the handle and, by doing so, to cause the material of the end plug 14, 64 to fail at the scores 30, 72. It is preferred for many uses that the handle be of a form that is immediately recognizable to the recipient as a handle to which the recipient is intended to apply force to open the container 10. Labeling, including words or symbols molded into the material of the end plug 14, may be used to assist the user to recognize the handle. It is preferred for many uses that the handle be of such a form that it is easy for the user to apply the necessary force. It is preferred for many uses that the handle be of a form that is not likely to foul or catch on other objects in shipping. The actual preferred shape will depend on the intended use and the intended user, as well as on the relative importance of the various functional aspects.

[0046] It will be appreciated by those skilled in the art, that the present invention may be practiced in various alternate forms and configurations. The previously detailed description of the disclosed embodiments is presented for purposes of clarity of understanding only, and no unnecessary limitations should be implied therefrom.