CARGO AIR BAG

Abstract: An air bag for bracing products shipped by a railcar, trailer or overseas container to prevent lengthwise and/or crosswise movement of the cargo includes a first sheet (16) of paperboard having parallel side and end edges folded inward­ ly defining a planar center section (16a) and overlapping sides (18) and ends (26), a second sheet (24) of paperboard of the same dimension as the center section (16a) facing the center section and having its marginal side and end edges (24a) interposed between the center section (16a) and the overlap­ ping side and end sections of the first sheet and glued to the side (18) and end (26) sections, and an inflatable bladder (22) between the two sheets. The bag is constructed of relatively stiff paperboard of a minimum of two laminated plys. Thus, the overlapping side and end edges of the first sheet define with the second sheet a peripheral border of a minimum of six laminated plys of paperboard. The bag has relatively good vertical stiffness when uninflated making it easy to use. The air bag is further characterized by its ease and economy of manufacture.

Description: This invention relates to cargo air bags. Inflatable air bags are used as bracing to reduce damage to products and materials, as well as labour and loading time in shipping cargo. Such bags, known as cargo air bags, are typically comprised of a plastic inflatable bladder which is surrounded by a multi-walled paper bag to protect the bladder from puncture. An inflation valve extends through the air bag and into the bladder such that the bladder may be filled and expanded with compressed air. The size of the multi-walled bag is such that it expands under the internal pressure of the gas. Such bags are manufactured in a variety of sizes to fill virtually any load pattern and void size and shape in the shipping of products. In use, the product to be shipped, for example, via a railcar, trailer or overseas container, is placed in the cargo container. Typically, the load does not fill the container completely and adjacent loads may be spaced from each other or spaced from the ends and side walls of the container. Without bracing of the load, the load would be subject to movement during shipping. The use of air bags prevents lengthwise and/or crosswise movement of such cargo so that the construction of bulkheads is not necessary. In use, an air bag is placed in the void between spaced pallets or load units or between the side or end walls of the container and the load. Thereafter, an operator inflates the bag with compressed air, the bladder and bag expanding to thereby fill the void and brace the load. To remove the load, it is only necessary to simply puncture the air bag so that it can deflate and remove it from the container. Air bags thus provide a fast and easy way to brace a load for shipment. Currently, air bags are typically manufactured by taking a length of multiple-layered paper, folding it on itself at its edge to form an overlapping seam generally along the centerline and then gluing the overlapping edges together. There is thus formed a multi-walled paper tube having open ends. The inflatable plastic bladder is then inserted in the tube by holding the tube up at both ends to expand it and sliding the bladder into the expanded tube. The ends of the bag are then closed and sealed to form the completed air bag. Such an airbag is known from US-A-3072270. This method of construction is relatively labour intensive since it is difficult to insert the bladder in the bag in the manufacturing process. Further more the step of inserting the bladder in the paper tube typically has to be carried out by hand. Additionally, in the construction of multi-walled air bags of this type, it is necessary to fold the paper on itself which weakens the paper fibers along the folded edges. Experience has shown that if there is a blowout of the bag because of the air pressure in the bag, the blowout typically occurs at the folded edge of the bag where the fibers have been weakened. Further, such air bags typically do not have much vertical stiffness, thus, when placed between the load by the operator, the paper bag tends to sag toward the floor, and the operator must attempt to hold the bag upright while at the same time inflate it. This can be an awkward operation. Viewed from one broad aspect there is herein disclosed a cargo air bag comprising: a first sheet portion of at least two plies of laminated paperboard which is folded along opposed parallel lengthwise and widthwise edges to define a generally planar center section and side and end sections extending therefrom; a second sheet portion of at least two plies of laminated paperboard of a length and width corresponding substantially to the length and width of said planar center section of said first sheet portion and which faces said center section, the second sheet portion being joined to the side and end sections of the first sheet portion, and an inflatable bladder between the first and second sheet portions; characterised in that the first and second sheet portions are separate sheets, the side and end sections of the first sheet portion are folded inwardly so as to overlap the centre section, and peripheral side and end portions of the second sheet portion are interposed between peripheral portions of the centre section of the first sheet portion and the side and end sections thereof, whereby there is provided a peripheral border around the bag of at least six plies of laminated paperboard in thickness. Viewed from another broad aspect there is herein disclosed a method of forming a cargo air bag comprising, placing an inflatable bladder on a central section of a first sheet of at least two ply laminated paperboard, placing a second sheet of at least two ply laminated paperboard over said bladder and folding edge portions of at least one of said first and second sheets inwardly so as to overlap the corresponding edges of the other of said first and second sheets, and bonding said first and second sheets together around the edges thereof so as to form a peripheral border around said bladder of at least six ply laminated paperboard. An embodiment of the invention will now be described by way of the accompanying drawings in which:- Fig. 1 is a view with parts broken away of a railcar illustrating an environment in which an air bag is used, Fig. 2 is an exploded view of an air bag according to a preferred embodiment, Fig. 3 is a view illustrating a step in the manufacture of an air bag according to the embodiment of Fig. 2, Fig. 4 is a view showing the completed bag of the embodiment of Fig. 2 before inflation thereof. Referring to Fig. 1, cargo air bags 10 keep cargo 12 shipped in a railroad car 14 tightly braced both laterally and lengthwise to prevent the cargo moving or shifting during transport, a railroad car 14 being illustrated in Fig. 1. It will be observed that bags 10a provide lengthwise bracing of the cargo 12 in a railroad car 14 by compacting and positioning the load toward the end walls thus eliminating lengthwise voids. They also cushion loads upon impact by absorbing shocks. The air bags also enlarge to fill voids that occur when cargo settles. Similarly bags 10b, positioned between lengthwise rows of lading, fill the voids in the crosswise direction holding the product firmly against the side walls. The air pressure in the bags exerts constant pressure on the load so that it is constrained against the side walls. The air bags 10b thus prevent side shifting of the load. Referring now to Fig. 2, an air bag according to a preferred embodiment comprises two paperboard elements 16, 24. In the manufacture of the air bag, a first rectangular sheet 16 of paperboard having a lengthwise and widthwise direction includes opposed side and end edges or flaps which may be folded inwardly along its lengthwise and widthwise directions, respectively, to form two folded side sections 18 and two folded end sections 26. The fold lines 20 of the side sections 18 and end sections 26 define a generally planar rectangular center section 16a having a defined length and width. The folded side and end sections 18 and 26, respectively, overlap portions of the center section 16a. An inflatable plastic bladder 22 is laid on the center section 16a of the first paperboard sheet 16. A second sheet 24 of paperboard having a length and width corresponding generally to that of the center section 16a of the first sheet 16 is placed on the bladder with marginal side and end portions 24a (Figs. 2,3 and 4) lying under the overlapping side and end sections 18 and 26 of the first sheet 16. The side and end sections 18 and 26 are glued to the side and end portions 24a of the second paperboard sheet and the two members pressed together. The first and second sheets are at least two ply laminated paperboard. In a preferred embodiment, each sheet has a thickness in the range of 0,5588-0,6096 mm (0.022-0.024 inches). As may be seen with reference to Fig. 4, the air bag 10 thus comprises first 16 and second 24 sheets of paperboard with folded side edges 18 and end edges 26 of the first sheet 16 laminating edge portions 24a of the section sheet 24 therebetween with an internal bladder enclosed therein. An inflation valve 28 extends through the first sheet permitting inflation of the plastic bladder with compressed air. The manufacture of the air bag of this embodiment thus considerably reduces the time and labour required in manufacture. That is, since it is not necessary to position a deflated plastic bag in an open paper tube but rather merely to lay it on the surface of first sheet 16 and then lay the second sheet 24 on the bladder, this operation can be carried out very simply and with considerably less space requirements than heretofore required. In addition, the air bag is relatively strong since it comprises six plys of laminated paperboard at the peripheral border of the bag, and eight plys in each corner. The six plys at the ends 26 provide the air bag with a relatively high degree of vertical stiffness such that it can be positioned in the voids and will support itself in a vertical direction while uninflated making inflation thereof considerably easier. Thus it will be seen that, at least in preferred forms, there is provided a cargo air bag that is more easily and economically manufactured than those heretofore available, which has increased resistance to blowout, good abrasion resistance, and which has a high degree of vertical stiffness making its inflation when placed in the void between spaced loads or between the load and container walls faster and easier. In accordance with a presently preferred embodiment of the invention, the cargo air bag is composed of a first sheet of relatively stiff paperboard which is folded on itself along opposed parallel side and end edges to thereby define a planar center section having folded and overlapping side and end sections. A second sheet of relatively stiff paperboard having a length and width corresponding to the length and width of the center section of the first paperboard sheet faces the center section of the first sheet with its side and end edges underneath the overlapping side and end sections of the first sheet. The inner surfaces of the overlapping sections are glued to the marginal side and end edges of the second sheet of paperboard. An inflatable plastic bladder lies between these two sheets. An inflation valve extends through the first sheet permitting inflation of the bladder. The two sheets are formed of a minimum of two plys of laminated paperboard. Thus, the folded side and end sections of the first sheet define with the interposed side and end sections of the second sheet a peripheral border of a minimum of six laminated plys. This provides the air bag with good strength and excellent vertical stiffness such that the air bag is essentially self-supporting in the void permitting its ready inflation by a single worker. The manufacture of the air bag of the above described embodiment is relatively simple. The first sheet is placed on a flat surface. A plastic bladder is laid on the center section of the first sheet and the second sheet is placed thereover. The side and end sections of the first sheet are folded inwardly. The folded side and end edges are glued to the second sheet. The overlapping sections are then pressed together to form the completed structure. Thus, in the manufacture of the described embodiment, it is not necessary to open a paper bag and manually insert a bladder therebetween. Moreover, it has been found that by the nature of the construction of the bag, including the six ply layer thickness of paperboard at the edges, the bag has a significant resistance to blowout. Still further, as stated, the laminated paperboard layers at the ends of the two sheets which extend in a vertical direction in use provide an air bag having a relatively high degree of stiffness in the vertical direction. Thus, it may be placed in the void between loads and will not sag or flop down before inflation making its positioning and inflation easy and fast.

Claims: A cargo air bag comprising: a first sheet portion (16) of at least two plies of laminated paperboard which is folded along opposed parallel lengthwise and widthwise edges to define a generally planar center section (16a) and side (18) and end (26) sections extending therefrom; a second sheet portion (24) of at least two plies of laminated paperboard of a length and width corresponding substantially to the length and width of said planar center section (16a) of said first sheet portion (16) and which faces said center section, the second sheet portion (24) being joined to the side (18) and end (26) sections of the first sheet portion (16), and an inflatable bladder between the first and second sheet portions; characterised in that the first (16) and second (24) sheet portions are separate sheets, the side (18) and end (26) sections of the first sheet portion (16) are folded inwardly so as to overlap the centre section (16a), and peripheral side and end portions (24a) of the second sheet portion (24) are interposed between peripheral portions of the centre section (16a) of the first sheet portion (16) and the side (18) and end (26) sections thereof, whereby there is provided a peripheral border around the bag of at least six plies of laminated paperboard in thickness. A method of forming a cargo air bag (10) comprising, placing an inflatable bladder on a central section (16a) of a first sheet (16) of at least two ply laminated paperboard, placing a second sheet (24) of at least two ply laminated paperboard over said bladder(22) and folding edge portions (18,26) of at least one of said first (16) and second (24) sheets inwardly so as to overlap the corresponding edges of the other of said first and second sheets, and bonding said first (16) and second (24) sheets together around the edges thereof so as to form a peripheral border around said bladder (22) of at least six ply laminated paperboard.

Inventors: LIEBEL, HENRY J.
Applicants: SIGNODE CORPORATION
Application year: 1986
Main classification: B61D45
IPC codes: B61D45