Corrugated lamp bulb wrapper

Abstract

An effective low-cost collapsible protective tube for lamp bulbs is obtained from a single rectangular sheet of single-faced corrugated paperboard having a series of regularly spaced parallel transverse fold lines connecting four trapezoidal side wall panels and having pairs of diverging inclined longitudinal fold lines at the ends of said side wall panels defining integral triangular self-locking end flaps. A pair of such end flaps are provided at each end of the corrugated tube at opposing corners and snap inwardly to provide resilient cushioning supports for the bulb. The tube provides the bulb with maximum protection against breakage due to impacts or crushing forces against the ends of the tube.

Description

BACKGROUND OF THE INVENTION

The present invention relates to protective tubes or wrappers for lamp bulbs, bottles and other bulbous articles and more particularly to low-cost corrugated paperboard tubes having self-locking end flaps which snap inwardly to provide resilient cushioning means for engaging the ends of a lamp bulb.

It is customary to package lamp bulbs in inexpensive single-face corrugated tubes, with one or two bulbs in each tube. Many different means have been proposed for assisting in holding the bulb in the tube or to protect the ends of the bulb but these have not been entirely satisfactory. The use of special means of this type with corrugated tubes has been limited because of their added cost and the tendency to interfere with insertion or removal of the bulb.

The more popular bulb wrappers are of simple construction and commonly rely on friction between the bulb and the corrugations of the wrapper to keep the bulb from falling out. The most convenient and inexpensive bulb wrappers are simple tubes of substantially square cross section formed from a single sheet of single-faced corrugated paperboard, sometimes with a divider to separate two bulbs. While this type of bulb wrapper has obvious disadvantages, it has heretofore been difficult to provide a simple and effective solution to the problem.

SUMMARY OF THE INVENTION

The present invention provides an admirable solution to the problem in a simple manner without the disadvantages of the prior art constructions and without adding much to the cost of manufacture or the cost of packaging. All that is necessary is to provide some additional inclined fold lines in the rectangular blank used to form the corrugated tube so that triangular self-locking end flaps are formed at opposite corners of the tube for cushioning engagement with the end of the lamp bulb. Such end flaps readily snap into position and remain in an effective cushioning position to prevent accidental loss or removal of the bulb.

The end flaps do not interfere with collapsing of the corrugated tubes for storage or stacking prior to insertion of the lamp bulbs and permit manufacture of the tubes of this invention using equipment of generally the same type as previously used for making conventional corrugated tubes.

In the practice of the present invention, a single blank of corrugated paperboard is used to form the protective wrapper or tube. Such blank is preferably generally rectangular and has a series of spaced transverse fold lines dividing the blank into four side-wall panels and has two end flaps at each side of the blank, each hingedly connected to an adjacent pair of side wall panels by inclined longitudinal fold lines which diverge from the midportion or apex of the end flaps.

The blank is folded and glued to form a protective tube having a pair of said end flaps at each end of the tube and at opposite corners of the tube. The fold lines are oppositely inclined at opposite ends of each side panel in such a manner that each end flap snaps inwardly and becomes locked in a position where it can provide a resilient cushioned support for the lamp bulb.

An object of the present invention is to provide an improved corrugated protective tube for lamp bulbs which can be manufactured at minimum cost.

A further object of the invention is to make a simple protective tube which provides superior protection for a lamp bulb while permitting easy insertion and removal of the bulb.

A still further object of the invention is to provide a simple inexpensive protective tube which provides maximum protection when the tube is dropped on its end or subjected to end crushing forces.

Another object of the invention is to provide an improved corrugated blank for a lamp bulb wrapper which may be mass produced at extremely low cost.

Another object of the invention is to provide a superior lamp bulb wrapper which may be folded and glued in a stiff flattened condition to facilitate stacking and handling and use in automatic equipment.

These and other objects, uses and advantages of the invention will become apparent to those skilled in the art from the following drawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective view of a tubular protective lamp bulb wrapper constructed according to the present invention;

FIG. 2 is a plan view on a reduced scale showing the blank used to form the protective tube of FIG. 1;

FIG. 3 is an end view of the protective tube of FIG. 1 on a reduced scale showing a lamp bulb mounted in the tube;

FIG. 4 is a side view of the assembled protective tube of FIG. 3 on the same reduced scale;

FIG. 5 is a schematic fragmentary transverse sectional view taken on the line 5--5 of FIG. 2; and

FIG. 6 is an end view of a flattened protective tube made from the blank of FIG. 2 before it is opened to receive the lamp bulb.

DESCRIPTION OF THE INVENTION

Referring more particularly to the drawings in which like parts are identified by the same numerals throughout the several views, FIG. 2 shows a preferred embodiment of the invention in which a single flat blank A is employed to form the protective corrugated tube T. The blank A is formed from a rectangular laminated sheet 1 of conventional single-faced corrugated paperboard consisting of a flat continuous facing layer or sheet 2 and a continuous corrugated layer 3 having regularly spaced, longitudinal grooves or corrugations 4 of uniform size extending parallel to the straight side edges 5 and 6. The layers 2 and 3 may be made of the same sheet material and are coextensive and glued or firmly adhered together at the ridges of the sheet 3 in the usual manner.

The blank A has four regularly spaced parallel transverse crease or fold lines 7, 8, 9 and 10 of the same length which are perpendicular to the corrugations 4 and parallel to the straight end edges 11 and 12. The fold lines divide the blank into first, second, third and fourth side wall panels 13, 14, 15 and 16, respectively, and a connecting "glue" panel 17 adapted to be overlapped at and firmly secured to the fourth side wall panel 16, for example by gluing it to layer 2 or layer 3 at either the inner or outer face of panel 16. The width of the latter panel may be less than that of panels 13, 14 and 15 but is preferably almost as great so that the glue panel 17 may be relatively narrow. The construction defined in this paragraph is conventional.

In accordance with the present invention, inclined longitudinal fold lines 22 to 29 are provided at opposite ends of the side wall panels which define four self-locking cushioning end flaps 18, 19, 20 and 21, each end flap decreasing in width in a longitudinal direction away from its midportion m or its apex a and being hingedly connected to an adjacent pair of said side panels along said inclined fold lines.

The shape of the inclined fold lines can vary somewhat but the corrugated sheet 1 resists bending of the side wall panels so that any curvature in the fold line should be limited. Such inclined fold lines are preferably generally straight so that each of the four side wall panels 18 to 21 is generally in the form of an isosceles trapezoid and each of the four end panels is generally in the form of an isosceles triangle, but it will be apparent that different constructions can also be used which function in a similar manner.

As shown each of the inclined fold lines 22 to 29 is straight and extends across each side wall panel substantially from one side to the other side, the fold lines at opposite ends of each side wall panel being oppositely inclined with respect to each other and with respect to the fold lines of the next adjacent side wall panel and being arranged so that the fold lines of each end panel diverge outwardly from the apex a and the midportion m. The end flaps 37 of the panel 17 preferably have the same inclinations as the fold lines 25 and 29 of panel 16.

The inclined fold lines 22 to 29 should preferably be inclined at an angle C of from about 50 to about 70.degree. relative to the transverse fold lines 7 to 10 when using a rectangular blank with straight sides 5 and 6 as shown in FIG. 2. Reduction of such angle to 45.degree. is indesirable and requires cutting away part of the end flap to eliminate interference when the flaps are folded into the tube T. Increasing such angle C to 80.degree. or higher in the blank A is less satisfactory because the end flaps would then be too narrow to engage a standard lamp bulb properly, but such a construction can be employed at one or both ends of the tube T if the blank is specially cut at the sides to increase the width of the end flaps at the fold lines 8 and 10 if the end flap is of such size as to engage and support the end of the lamp bulb.

The width w of each end flap at the midportion m is preferably at least one-half the width of the side wall panels 13, 14 and 15 and is preferably no greater than three-fourths of the latter width so that inward folding of one end flap does not interfere with folding of the other end flap. Preferably the end flaps 18 to 21 have a width such that the midportions m of adjacent opposing end flaps are spaced apart a suitable distance when the tube T is in the assembled position of FIGS. 3 and 4 and has a square cross section as shown therein. Such distance d (FIG. 3) should be such that the inwardly projecting portions 31 to 34 of the end flaps 18 to 21 adjacent apex a can engage or support the glass end portion 35 or the threaded screw-in portion 36 of the bulb B.

Each of the end flaps 18 to 21 is of the self-locking type and is constructed to bend and snap over a dead-center point inwardly into the tube T as it is opened up from the flat form of FIG. 6 and to provide a high resistance to outward movement of the bulb B. In order to facilitate such bending, the central portions of the end flaps are preferably creased. In the preferred construction the transverse fold lines 8 and 10 have end portions 8a and 10a extending across the end panels and providing crease lines which divide the panels in half. As shown the end flaps 18 to 21 are divided into eight end flap portions 18a, 18b, 19a, 19b, 20a, 20b, 21a and 21b of the same size, each in the form of a right triangle which extends substantially the full width of the associated side wall panel, but it will be understood that the desired results can be obtained with end flaps of substantially different shape. Each of said end flap portions is hingedly connected to its associated side wall panel along more than half and preferably more than three-fourths of the width of the side wall panel and for a distance sufficient to provide the end flaps with the desired snap-in self-locking action.

The simple blank shown in FIG. 2 is preferred over more complicated arrangements, and it is usually best to employ straight edges 5 and 6 on the blank without substantial cutouts in the end flaps. However, it will be understood that the end flaps can be specially cut or shaped to fit and support an end portion of the article being packaged, such as portion 35 or 36 of the bulb B.

The inclined longitudinal fold lines 22 to 29 may be formed by perforating and/or creasing operations using conventional equipment. The same is true when forming the transverse fold lines 7 to 10 on the blank, but the latter are preferably creased without cutting to avoid weakening the corners of the tube. As herein shown the transverse fold lines are formed by creasing only the corrugated layer 3 and the inclined fold lines are formed by spaced aligned perforations in the layers 2 and 3. Except for the perforations, the blank A is conventional.

The crease lines 7 to 10 are preferably parallel and equally spaced so that the protective tube T is collapsible and has the same square shape and size at both ends. This permits completing the manufacture of the tubes in a flattened condition and reduces the costs of handling the tubes after they are glued. As shown in FIG. 6, the blank A may be folded only at the crease lines 8 and 10 and the connecting panel 17 may be glued to the side panel 16, preferably outwardly of panel 16, to provide a stiff flat article 40 convenient for stacking, shipping or use in automatic equipment. The article 40 is relatively stiff and remains generally flat until such time as the blank A is folded at the crease lines 7 and 9 to form the open-ended tube T.

Lamp bulbs, bottles or like fragile articles may be placed in the tubes T either manually or using automated equipment. After the article is inside the tube, the end flaps 18 to 21 may easily be snapped inwardly to the cushioning position shown in FIGS. 1, 3 and 4 by bending the central portions of the flaps inwardly. This causes the flaps to become locked in an effective cushioning position for engaging and/or supporting the end portion of the lamp bulb or other article. The inclined hinged connections between the end flaps strongly resists outward movement of the flaps to prevent the article from sliding endwise out of the tube, but the corrugated tube will deform so that the end flaps act as resilient cushions to yieldably resist such endwise movement. This minimizes the chance of breakage if the protective tubes are dropped on their ends and is particularly important when shipping the more expensive lamp bulbs. Also the shape of the tube T is such that it has improved resistance to crushing forces exerted on the projecting corners of the tube and is better able to cushion such forces and prevent damage to the lamp bulb.

The side wall panels 13 to 16 and the end flaps 18 to 21 of the tube are relatively stiff and resist bending due to the corrugated construction. For this reason, substantial force is required to snap the end flaps inwardly. However, the midportion m of each end panel will bend or deform when such force is applied to permit the desired movement. Also said midportion will yield and deform to provide an effective cushioning means when in engagement with the lamp bulb. If the tube T is dropped on an end corner, for example, or otherwise subjected to axial shock forces, the yieldable end flap will engage the end of the bulb and act as a cushion while at the same time preventing the bulb from sliding out of the tube. Excellent protection is provided even when the bulbous article in the tube T has substantial weight.

If desired, the end flaps 18 to 21 may be so located that they engage both ends of the light bulb to position the bulb in the tube. In the construction shown in FIG. 4, for example, the innermost projecting portions 31 to 34 of the end flaps engage both ends of the bulb B.

When it is desired to remove the bulb B from the closed wrapper of FIG. 4, it is only necessary to move the end flaps outwardly to open one or both ends of the tube T permitting endwise removal of the bulb.

It will also be apparent that the corrugated protective tube of the present invention can be constructed to receive two lamp bulbs. For example, it is conventional, when shipping household lamp bulbs, to employ corrugated tubes of square cross section with a special glued panel positioned to provide an inclined corrugated divider between the two bulbs.

While some of the advantages of the present invention may be obtained with polygonal protective tubes of unusual shape, it is preferable to employ tubes with the same width and same cross section at both ends and having a generally square or rectangular cross section, rather than a hexagonal cross section.

It will be understood that, in accordance with the provisions of the patent laws, variations and modifications of the specific devices disclosed herein may be made without departing from the spirit of the invention.

Claims

Having described my invention, I claim:

1. A flattened collapsed tube of generally rectangular shape for packaging lamp bulbs formed from a blank comprising a unitary generally rectangular single-faced corrugated sheet having longitudinal corrugations and four regularly spaced parallel transverse crease lines extending across the sheet and dividing the sheet into a glue panel and first, second, third and fourth side wall panels, said glue panel extending from the first side wall panel and adapted to be overlapped at the fourth side wall panel, the glue panel being connected to said first side wall panel along the first of said transverse crease lines, the first and second side wall panels being connected along the second transverse crease line, and the third and fourth side wall panels being connected along the fourth transverse crease line, and eight inclined longitudinal perforated score lines at the opposite ends of said side wall panels which extend between the transverse crease lines at opposite sides of that panel to define triangular flap portions, said score lines being inclined at an angle (C) of from about 50 to about 70 degrees with respect to said transverse crease lines and located so that the wide portions of said triangular flap portions are located at said second and fourth transverse crease lines, said flattened tube being folded only at said last-named crease lines with the first side panel overlying the second side panel, the glue panel adhered to the fourth side panel, and said last-named panel overlying the third side panel.

2. A blank for forming a folded protective tube for packaging round lamp bulbs, said blank comprising a generally rectangular unitary single-faced corrugated sheet having a series of regularly spaced parallel transverse fold lines dividing the sheet into four side wall panels of substantially equal width, whereby the blank is adapted to provide a collapsable protective tube of generally square cross section, a pair of self-locking cushioning end flaps at each side of said corrugataed sheet forming the outer edge of the sheet, each end flap being longitudinally elongated and decreasing in width in a longitudinal direction away from the midportion of the flap and being hingedly connected to an adjacent pair of said side wall panels along inclined longitudinal fold lines which diverge from the midportion of the flap, the midportion of each end flap being located in alignment with one of said transverse fold lines, said corrugated sheet having straight sides forming the outer edges of said end flaps.

3. a blank according to claim 2 wherein each of said inclined fold lines is inclined at an angle of from about 50.degree. to about 70.degree. relative to said transverse fold lines.

4. An open-ended protective tube of generally square cross section for packaging a round lamp bulb, said tube being formed of a faced corrugated sheet having four transverse fold lines dividing the sheet into four side wall panels, said side panels being hingedly connected together at said fold lines with the corrugations extending around the periphery of the tube and adapted to engage the bulb at the inside of each panel, a pair of self-locking end flaps at each end of said tube located at opposite corners of the tube and defining the outer edge of said sheet, each end flap integrally extending from the ends of a pair of adjacent sidewall panels along inclined fold lines which diverge from the junction of said adjacent sidewall panels toward the end of the tube, said fold lines providing hinge means which enables the end flap to snap inwardly and become located in an effective article-retaining position with its edge spaced from the edge of the adjacent flap, the central portion of each end flap being bent inwardly to provide resilient cushioning means for engaging the end of said lamp bulb and for holding the lamp bulb in the tube.

5. A protective tube according to claim 4 wherein said inclined fold lines are inclined at an angle of from about 50.degree. to about 70.degree. relative to said first-named fold lines.

6. A protective tube according the claim 4 wherein each of said end flaps is generally triangular and has a maximum width no more than three-fourths the width of each side wall panel.

7. A protective tube according to claim 4 wherein the central portions of the opposing end flaps at each end of the tube are spaced apart a distance less than one-half the width of each side panel when the end flaps are folded inwardly into the body of the tube so that the end flaps provide a resilient support for the lamp bulb.

8. An open-ended protective tube of generally square cross section containing a lamp bulb of circular cross section, said tube being formed of a faced corrugated sheet having four transverse fold lines dividing the sheet into four side wall panels, said side panels being hingedly connected together at said fold lines with the corrugations extending around the periphery of the tube and engaging the bulb at the inside of each panel, a pair of self-locking end flaps at each end of said tube located at opposite corners of the tube and defining the outer edge of said sheet, each end flap integrally extending from the ends of a pair of adjacent sidewall panels along inclined fold lines which diverge from the junction of said adjacent sidewall panels toward the end of the tube, said fold lines providing hinge means which enables the end flap to snap inwardly and become located in an effective article-retaining position with its edge spaced from the edge of the flap, the central portion of each end flap being bent inwardly to provide resilient cushioning means for engaging the end of said lamp bulb and for holding the lamp bulb in the tube, each of said end flaps being generally triangular and having a maximum width no more than three-fourths the width of each side wall panel.