WO1989006625A1

WO1989006625A1 - Pallet constructed without nails

Info

Publication number: WO1989006625A1
Application number: PCT/AU1989/000017
Authority: WO
Inventors: Bruce Alexander Mcphee
Original assignee: Bruce Alexander Mcphee
Priority date: 1988-01-21
Filing date: 1989-01-20
Publication date: 1989-07-27

Abstract

A pallet is formed without nails by using a pair of hollow steel bearers (10) of rectangular cross-section, each bearer having an upper wall, a lower wall, an inner wall (15) and an outer wall (13), and being closed by a pair of end plates (12). Corresponding upper and lower linear arrays of rectangular openings are formed in the inner walls of each bearer, adjacent to the upper and lower edges thereof. Upper and lower arrays of planks or slats (11), which may be of softwood, extend between the bearers, with the ends of the planks or slats passing through the rectangular openings. Steel rods (51) or tie bars - at least two per pallet - also extend between the bearers. The steel rods are adjustable in length, their adjustment mechanisms (53, 54, 55) enabling the bearers to be pulled towards each other until the ends of the planks or slats abut firmly against the inside of the outer walls (13) of the bearers and the rods or tie bars are tensioned. Optional features include a pair of side apertures (14) in each bearer to receive the tynes of a fork-lift, and tongues (12A) on the end plates (12) to protect the end slats or planks (11) of the arrays.

Description

TITLE; "PALLET CONSTRUCTED WITHOUT NAILS"

Technical Field

This invention concerns pallets. More particularly, it concerns a pallet made from steel and wood without the use of nails. Such a pallet can be manufactured using relatively inexpensive wood, nevertheless it will be strong and capable of withstanding the usual treatment to which pallets are subjected.

Background The conventional pallet is made from hardwood. It comprises two linear arrays of cross-planks or slats, which extend between a pair of bearers. Each slat is nailed at each end to a respective bearer, and usually it is also nailed to an intermediate central bearer. Hardwood has to be used for the cross-planks and bearers of such pallets, even though it is considerably more expensive than softwood timber such as pine, because nails are used to assemble the pallet.

In addition to the- cost factor in the manufacture of wooden pallets (which is partly related to the increasing difficulty in locating suitable hardwood), these conventional wooden pallets have a number of disadvantages. The disadvantages include: (a) the fact that the pallets are easily damaged by careless handling by the operators of fork-lifts, particularly (i) when the tynes of the fork-lift strike an end slat and dislodge it from its associated nails, and hence from the bearers, and (ii) when a fork-lift tyne is pushed into the end grain of a bearer during movement of the pallet by the fork-lift prior to the lifting of the pallet by the fork-lift, thus splitting the timber of the bearer;

(b) the fact that when (as often happens) a pallet is dropped from a truck or loading dock and lands on a corner, the pallet is distorted diagonally;

(c) the possibility of damage being caused, by any nails protruding from the pallet, to goods on the pallet which have been bagged or packed in cartons; and (d) the inherent weakening of the timber slats when nails are driven through the ends of the slats - often causing the wood of the slat to split.

It has long been recognised that it would be advantageous if a nail-free pallet could be provided in place of the conventional wooden pallet.

Various alternative pallet constructions have been tried, but none has been successful. For example, an all metal pallet has been made, but when that type of pallet is lifted on the metal tynes of a fork-lift truck, the slats of the pallet slide on the tynes as a result of the lack of friction, with disastrous results. Another type of nail free pallet has been described in the specification of my Australian patent application No. 32537/84. That pallet, however, was not strong enough to withstand the normal abuse of pallets.

Disclosure of the Present Invention

It is an object of the present invention to provide a nail-free pallet which avoids, or minimises, the above-noted disadvantages of the conventional wooden pallet.

This objective is achieved by a pallet which has two bearers fabricated from steel, between which two linear arrays of wooden slats or planks extend. Each bearer has a hollow rectangular cross-section and the inner wall of the bearer has a series of rectangular openings along its upper and lower edges. These openings provide apertures for receiving the slats or planks of the pallet. Fastening means, in the form of at least two (and preferably four) steel rods, or flat bars or the like, are used to establish connections between the two bearers of the pallet in the vicinity of the end planks or slats of the pallet. The length of each of the connecting rods, flat bars or the like which constitute the fastening means, is adjustable, this adjustment being used to pull the bearers towards each other until the ends of the wooden slats (which have been positioned within the hollow bearers) abut firmly against the outer walls of the bearers, thus making the pallet a rigid structure.

Thus, according to the present invention, there is provided a pallet comprising a pair of elongate bearers separated by an upper array of planks or slats and a lower array of planks or slats, each plank or slat having its longitudinal direction at right angles to the elongate direction of the bearers, characterised in that:-

(a) each bearer is a hollow steel member of rectangular cross section, having an upper wall, a lower wall, an inner wall and an outer wall;

(b) each inner wall has an upper and a lower linear array of rectangular openings formed therein, said openings being adjacent to the upper and lower edges of the inner wall and having dimensions such that each opening receives one of said slats or planks; and (c) fastening means extending between said bearers, said fastening means being - provided with tensioning means to adjust (i) the length thereof which extends between the inner walls of the bearers and (ii) the tension within the fastening means.

As indicated above, preferably the fastening means comprises at least two tensioned steel rods or tie bars mounted in the vicinity of respective end planks or slats of the upper and lower arrays thereof, at opposed ends of the bearers. Preferably, each bearer is fabricated from a length of channel section, to which an elongate steel plate has been welded across the ends of the arms of the channel section. With this construction, the steel plate will form the inner wall of the bearer. Each end of each bearer is preferably closed by a rectangular end plate. If the bearers are formed by welding an elongate steel plate across the ends of the arms of a channel section steel member, the linear arrays of rectangular openings will normally be pressed or cut out of the elongate steel plate before it is welded to the channel section. If the linear arrays of openings are pressed out of the elongate steel plate, the pressing is preferably effected to leave flaps of metal which assist in locating the slats or planks within the rectangular openings, and in strengthening the pallet.

To enable the pallet to be moved by a fork-lift approaching the side of the pallet (which is not possible with a conventional wooden pallet), each bearer may have a pair of correspondingly located rectangular apertures ("side apertures")in its inner and outer wall. Each such rectangular side aperture has dimensions which enable it to loosley receive a tyne of a fork-lift and the centres of the side apertures in each wall of the bearer are spaced apart by a distance equal to the separation of the centres of the tynes of a fork-lift. In such a construction, a short length of box section steel will extend between the corresponding side apertures in the inner and outer wall, and be welded to the inner and outer walls, to provide access channels for the tynes of the fork-lift.

The pallet may be supplied in kit form for assembly by a user.

A preferred embodiment of the pallet of the present invention will now be described, by way of example, with reference to the accompanying drawings.

Brief Description of the Drawings Figure 1 is a top view of a pallet constructed in accordance with the present invention.

Figure 2 is a sectional view at II-II of the pallet of Figure 1.

Figure 3 is an oblique view of the pallet of Figures 1 and 2.

Figure 4 illustrates a preferred assemblage of components for constructing the bearers of the pallet of Figures 1, 2 and 3.

Figure 5 illustrates one way in which steel rods may be used to give the pallet rigidity. Detailed Description of the Illustrated Embodiment The pallet illustrated in Figures 1, 2 and 3 consists of a pair of bearers 10 which are separated by an upper and a lower array of slats or- planks 11 (for convenience, only one end plank of the lower array has been shown in Figure 3). Each bearer 10 is a hollow steel member of rectangular cross-section, closed at each end by a steel plate 12. The pallet also includes (see Figures 2 and 3) the optional side apertures to provide side access for the tynes of a fork-lift, in the form of a pair of box section lengths 14 of steel within each bearer, extending between the respective outer wall 13' and inner wall 15. The planks or slats 11 are of timber, and they extend between the insides of the outer walls 13 of the bearers, passing though respective openings in the inner walls 15 as they do so.

The currently most preferred method of constructing the bearers 10 is shown in Figure 4. A channel section steel member 40 has a pair of rectangular side apertures 44 cut into its web 41 (which forms the outer wall 13 of a bearer 10) to receive the short lengths 14 of box section steel. Generally U-shaped steel members 43 are welded (along flanges 43A at the ends of the arms of the "U") to each arm 42 of the channel section member 40, near each end thereof. Each U-shaped member 43 cooperates with a respective steel rod (or an equivalent tie bar) to stiffen the pallet construction, as will be explained in more detail below. Circular apertures 45 (these apertures 45 need not be circular, but may be any shape) are formed in the web 41 of the channel section member, adjacent to the generally U-shaped members 43, but four of the apertures 45 need not be provided in all the bearers (as will be appreciated from the further description below) ; in mass production of the pallets, a pair of apertures 45 may be formed at one end only of each channel section member 40.

An elongate steel plate 46, also shown in Figure 4, is welded at its elongate edges across the arms 42 of the channel section member 40 to convert the channel section member 40 into a hollow steel member of rectangular cross-section. The plate 46 has the same length as the member 40, and has rectangular side apertures 47 cut into it. The size and location of the rectangular side apertures 47 correspond with the size and location of the rectangular side apertures 44 in the member 40. The ends of a pair of short lengths 14 of box section steel are welded to the edges of the apertures 44 and 47, to provide the receiving channels for the tynes of a fork-lift, to which reference was made above.

A series of pressings in the region of the upper and lower edges of the elongate steel plate 46 form vertical flaps 48 (which, when the bearer is assembled, are located within the bearer) and horizontal flaps 49 (which project away from the bearer when it has been assembled)^'. The regions of the plate 46 which have been pressed out to form the flaps 48 and 49 provide rectangular openings in the plate 46 when the plate 46 has been welded to the channel section member 40. Such rectangular openings have dimensions which correspond to the cross-sectional dimensions of the slats or planks 11. In fact, the flaps 48 and 49 assist in supporting the slats or planks in position when the pallet has been assembled. It will be appreciated, however, that the flaps 48 and 49 are preferred features; the openings for the slats or planks may be created simply by removing rectangular pieces of metal from the upper and lower edge regions of the elongate plate 46.

A pair of square (or rectangular) steel plates 12 are welded to^' the respective ends of the member 42 and the plate 46 to close each end of the assembled bearer. Each end plate 12 of the assemblage shown in Figure 4 may be provided with rectangular or generally triangular tongues 12A (shown in dashed outline in Figure 4) to provide protection against damage by a fork-lift tyne to the end slats 11 (and also to the end flaps 49) of the elongate plate 46.

The channel section member 40 and the elongate plate 46 are preferably made from 3 mm thick high-tensile steel (HIlO or LIlO) and the end plates 12 are preferably of 6 mm steel. However, lighter gauge steel - or heavier gauge steel - may be used to construct the bearers. The assembled bearer is preferably square in section, measuring 150 mm by 150 mm. (Note: a square is a special instance of-a rectangle. )

After the bearers 10 have been fabricated, the pallet is assembled by inserting the ends of planks 11 into the openings formed along the top and bottom of the inner wall 15 of two bearers 10, then pulling the two bearers towards each other using the fastening means of the present invention. In the illustrated embodiment, the fastening means comprises a plurality of steel rods 51 as shown in Figure 5. Each steel rod 51 has one end 52 formed as a hook and the other end 53 threaded to receive a nut. The hooked end 52 is passed through the tunnel formed by a respective generally U-shaped member 43 and is hooked over the edge of the member 43. The threaded end 53 is passed through the tunnel formed by the corresponding U-shaped member 43 in the other bearer 10. A washer 54, having an outer diameter which is greater than the width of the tunnel formed by the U-shaped member 43, is placed on the end of the rod 51, then a nut 55 is threaded on to the end 53. A socket spanner, or a tube spanner, projecting through the appropriate aperture 45 in the bearer, is used to tighten the nut 55 on the end 53 of the rod 51, until the rod 51 has pulled the two bearers together to such an extent that the ends of the planks or slats 11 bear firmly against the insides of the outer walls 13 of the pallet. This makes the pallet a rigid structure. - li ¬

lt will be appreciated that other known ways of adjusting the length of a rod 51 (for example ^"a nut and washer arrangement on each end) may be used instead of the illustrated adjustment mechanism. It will also be appreciated that other forms of the fastening means may be used. Among those alternatives is a flat tie bar, which has at least one slot in it so that a wedge can be inserted into the or each slot to separate the bearers. The advantage of such of tie bar arrangement is that it is a simple matter to dismantle a pallet, for to remove the tensioning of the fastening means, all that is required is the removal of the wedges using a heavy hammer.

Preferably, either (a) the end planks of each array in the pallet are grooved so that when the pallet is assembled, the rods 51 are recessed within the end planks or (b) each rod or tie bar is mounted to be adjacent to the slats or planks and thus between a pair of slats or planks and within the linear arrays. In this way, it will not be possible to damage the rods 51 or the tie bars when the pallet is being moved by a fork-lift. Normally, four rods 51 or tie bars will be used for each pallet, but it is possible to assemble a pallet using only two rods. It is also possible to include additional bracing rods, if required, at other locations in the pallet. It will be appreciated that in order to achieve the optimum strength of the pallet, each plank or slat 11 should have the same length, and be square on its ends. It will also be appreciated that the present invention has enabled a rigid and strong pallet to be constructed without the use of nails, and that when performing the present invention, the cheaper softwood planks or slats can be used as well as hardwood planks or slats. An optional modification is to rebate the ends of the wooden slats or planks so that when a pallet is assembled, the outer surfaces of the planks are flush with the upper and lower faces of the bearers.

An incidental benefit of the present invention is that the name or trade mark of the owner of the pallet may be pressed into or welded onto the outer walls 13 of the pallet, thus enabling the owner of the pallet to be readily identified. With conventional wooden pallets, the owner's name is usually painted on to the bearers of a pallet, and the paint is abraded off during use of the pallet. Thus the owner of a pallet that has been used for a reasonable period cannot be identified readily.

It should be noted that although specific embodiments of the present invention have been illustrated and described above, variations and modifications to the pallet can be made without departing from the present inventive concept. For example, the bearers may be made from a rectangular steel tube with the necessary apertures formed therein.

Claims

1. A pallet comprising a pair of elongate bearers (10) separated by an upper array of planks or slats (11) and a lower array of planks or slats (11), each plank or slat having its longitudinal direction at right angles to the elongate direction of the bearers, characterised in that:-

(a) each bearer is a hollow steel member of rectangular cross section, having an upper wall, a lower wall, an inner wall (15) and an outer wall (13);

(b) each inner wall has an upper and a lower linear array of rectangular openings formed therein, said openings being adjacent to the upper and lower edges of the inner wall and having dimensions such that each opening receives one of said slats or planks; and

(c) fastening means extending between said bearers, said fastening means being provided with tensioning means (54, 55) to adjust (i) the length thereof which extends between the inner walls of the bearers and (ii) the tension within the fastening means.

2. A pallet as defined in claim 1, in which said fastening means comprises at least two steel rods (51) which extend between said bearers in the vicinity of respective end planks or slats of the upper and lower arrays thereof, at opposed ends of the bearers.

3. A pallet as defined in claim 1 or claim 2, in which each bearer is fabricated from a length of channel section (40) having upper and lower channel arms (42) extending from a web (41), an elongate steel plate (46) being welded at its elongate edges to the edges of said channel arms (42) to form said inner wall, said elongate plate having a plurality of rectangular portions thereof at spaced-apart locations on its elongate edges removed therefrom to form said upper and lower linear arrays of rectangular openings.

4. A pallet as • defined in claim 3, in which the removed rectangular portions of said elongate plate (46) are pressed therefrom to form, at each of said rectangular portions, (i) a pair of flaps (48) extending at right angles into said' bearer from the respective side edges of the rectangular portion, and (ii) a flap (49) extending outwardly from the bearer at right angles to the plane of said elongate plate, from the edge of the rectangular portion which is parallel to, but spaced from the elongate edges of said elongate plate.

5. A pallet as defined in claim 2, or as defined in claim 3 or claim 4 when appended directly or indirectly to claim 2, further characterised in that at least one generally U-shaped member (43) is affixed within each said bearer to, respectively, the upper and lower arms (42) of said channel section; each said U-shaped member forming a tunnel which extends transversely of its associated bearer and which is dimensioned to enable one of said steel rods to be pushed through the tunnel; a respective aperture (45) being formed in said web (41) adjacent to each said U-shaped member.

6. A pallet as defined in claim 5, in which four generally U-shaped members are mounted within each bearer, adjacent to the ends of the upper and lower arms of the channel member.

7. A pallet as defined in claim 5 or claim 6, in which said steel rods are mounted between respective pairs of said U-shaped members within said bearers.

8. A pallet as defined in claim 7, in which the mounting of each said rod between the bearers comprises passing the rod through the respective pair of U-shaped members, hooking one end of the rod over an end of one of the U-shaped members and applying retention means to the other end of the rod.

9. A pallet as defined in claim 6, in which said retention means comprises a washer (54) held in contact with the respective U-shaped member by a nύt (55) on the threaded other end (53) of said rod, said nut and threaded other end comprising said tensioning means.

10. A pallet as defined in any preceding claim, further characterised in that each bearer includes a complementary pair of rectangular apertures (44,47) within its inner and outer walls; said rectangular apertures being spaced apart from each other by a distance equal to the spacing of the tynes of a fork-lift, and having dimensions sufficient to loosely receive the tynes of a fork-lift; a respective length (14) of box steel extending within the bearer between each complementary pair of the rectangular apertures, each said length of box steel being welded to the- edges of its associated rectangular apertures.

11. A pallet as defined in any preceding claim, in which each end of each bearer is closed by a respective metal plate (12) welded thereto.

12. A pallet as defined in claim 10, in which each metal plate has at least one tongue (12A) extending from a corner thereof to provide protection for an end plank or slat of the upper or lower array of planks or slats.

13. A pallet as defined in any preceding claim, in kit form, comprising a pair of said bearers, a plurality of said planks or slats sufficient to form said arrays, and said fastening means.

14. A pallet as defined in any preceding claim, in which said planks or slats are of softwood.

15. A nail-free pallet substantially as hereinbefore defined with reference to the accompanying drawings.