WO1992012905A1

WO1992012905A1 - Pallet

Info

Publication number: WO1992012905A1
Application number: PCT/SE1991/000890
Authority: WO
Inventors: Ture Marklund
Original assignee: Npf Nordisk Plåtformning Ab
Priority date: 1991-01-29
Filing date: 1991-12-19
Publication date: 1992-08-06
Also published as: AU9177391A; SE9100273A0; SE9100273D0

Abstract

A pallet comprising a load-carrying platform (3) which includes transverse stiffening ridges (2) and which is supported at least at its mutually opposing long edges or sides (5) by support beams (4) which extend perpendicularly to the stiffening ridges of the platform and which present therebetween a space into which lifting forks can be inserted from the sides of the pallet and which beams and which platform are made from corrugated metal plate, wherein the corrugations (2) form the platform stiffening ridges and extend along the sides of the support beams, and wherein the inside (11) of each such support beam forms a support leg which acts on the underside (13) of the platform, and wherein the end part (12) of respective legs that face towards the underside of the platform are locked in a generally perpendicular position in relation to the platform (3) in a locking groove (14) provided in a rail (15) mounted on the underside of the platform. In order to improve the stability and the impact durability of pallets of this kind and to enable the pallet to be transported readily on roller paths, a number of beam-supporting cross-stays (33) are disposed between the beams (4).

Description

PALLET

The present invention relates to a loading pallet of the kind comprising a load support platform which is provid- 5 ed with transverse stiffening ridges and which is sup- ) ported at mutually opposing longitudinal edges thereof by support beams of general U-shaped cross-section which extend perpendicularly to the stiffening ridges and which present therebetween a space into which lifting

10 forks can be inserted from the two short sides of the pallet and each of which beams is formed integrally with the platform made of corrugated metal plate, wherein the corrugations form said pallet stiffening ridges and also extend along the sides of the generally U-shaped support

15 beams, and wherein the inside of each such support beam forms a support leg which acts on the underside of the platform and at a distance from one longitudinal edge thereof, and wherein the end part of respective legs that face the underside of the platform are locked in a

20 generally perpendicular position in relation to the platform in locking grooves which extend at right angles to the corrugations and which are provided in a rail mounted on the underside of the platform.

25 So-called loading pallets used for the transportation, materials handling and, at times, also for the storage of materials have earlier been, and still are to some extent, made of pieces of wood which are nailed together to form a platform-like structure whose under and upper 30 sides are substantially open and which has openings in at least two mutually opposing side surfaces - a so- called two-way pallet, and preferably in all four side

. surfaces -a so-called four-way pallet- for receiving the lifting forks of a truck, tractor or like vehicle that 35 is equipped with lifting forks or tines. Because of the low impact strength and mechanical strength of such pallets, a drawback which is highly disadvantageous in the present context, and because of the tendency of such pallets to absorb water and the increasing lack of suitable wood, resulting in higher pallet prices, endea- vours have long been made to replace the wooden pallet with a pallet made from some other suitable material, although without success. The majority of loading pal¬ lets that are accepted commercially are still made of wood. Loading pallets of the aforedescribed kind made of corrugated metal plate, however, are being used to an increasing extent. This type of metal pallet, and also other known metal pallets, have the fundamental drawback that box beams which support the load support platform are unable to withstand to any great extent the impact forces to which they are subjected by misaligned lifting forks, for instance, and are easily buckled or bent as a result thereof. Furthermore, known metal pallets can only be transported on so-called roller paths with great difficulty, which is considered to be a serious drawback and which is one of the reasons why metal pallets have not been totally accepted.

Consequently, it is an object of the present invention to solve these problems and thus to provide a metal loading pallet which is able to withstand impact forces and other forces, which has a long useful life and which is constructed so as to enable the pallet to be trans¬ ported on a roller path.

These and other objects are achieved with an inventive loading pallet having the characteristic features set forth in the following claims.

The invention will now be described in more detail with reference the accompanying drawings, in which Figure 1 is a perspective view of one embodiment of an inventive loading pallet, seen obliquely from above; Figure 2 is a side view of the pallet illustrated in Fig. l; Figure 3 is an enlarged view of an end part of the illustrated pallet; Figure 4 is a sectional view taken generally on the line IV-IV in Fig. 3; Figure 5 shows the pallet from beneath; Figure 6 is an enlarged view of a part of the pallet provided with a friction enhancing coating; and Figure 7 is a cross-sectional view of a tube of flat oval cross-section forming part of the inventive pallet.

Each inventive loading pallet is made of metal plate, more specifically corrugated plate and then preferably steel plate 1, which has preferably trapezoidal corruga¬ tions 2, forming crests and troughs. The pallet includes a platform 3 which forms a load support surface and which is supported along both longitudinal sides 5 by box-like, more appropriately U-shaped supporting and carrying beams 4 which extend perpendicularly to the corrugations 2, said beams forming therebetween and beneath the platform 3 a space 6 for receiving the lifting forks of a loader at each short side 7.

Both beams 4 of the inventive loading pallet are formed from a piece of metal plate and preferably from the same piece of metal plate as that from which the platform 3 is made, by bending generally at right angles a corru¬ gated metal plate starting blank, which has been cut to an intended length and width, in sequence along general¬ ly parallel lines which extend perpendicularly to the corrugations of said blank and which are mutually spaced to continuous corners 8, 9 and 10 (Fig. 3) of respec¬ tive beams, wherein the first formed or bent corner 8 forms a transition or junction between the platform 3 of the pallet and respective beams 4. The width of respec- tive beams is determined by the distance between the corners 9 and 10 and can be varied so as to obtain wider or narrower beam widths. The distance between the cor¬ ners 8 and 9, on the other hand, shall, of course, be essentially equal to the last obtained corner 10, formed by bending the plate at right angles, and the free edge of the blank, so that the free end 12 of the inside 11 of the beam will lie in abutment with the underside 13 of the platform 3 and there function as platform sup¬ porting leg which also enhances the load carrying capac¬ ity of the platform, said free end 12 being formed by the free end edge of the starting blank.

The free end 12 of the inside 11 of each beam is insert¬ ed into a respective locking groove or channel 14 which extends generally at right angles to the platform σorru- gations 2. The smallest width of the locking groove 14 is preferably slightly larger than the total height of the corrugations. The locking groove 14 functions to lock and fixate the insides 11 of respective beams in a substantially vertical or a truly vertical position in relation to the platform 3, as clearly shown in Fig. 3 for instance. The locking groove 14 is formed in a reinforcing rail or support rail 15 made of a bendable or foldable material. One such rail 15 is secured to the underside 13 of the platform, at each longitudinally extending edge part 5. Each rail 15 has a length which corresponds to the length of the platform between its end or short sides 7 and, in addition to the locking groove 14, includes an attachment strip 17 which is level with the bottom 16 of the groove and which, simi- lar to groove bottom 16, abuts the underside 13 of the platform and is connected thereto by means of the so- called "tog-lock method" or some other suitable method in one or more rows, as shown schematically at 18 in Fig. 3.

The side 19 of the fastening strip 17 that faces towards the locking groove is formed by one leg of a stiffening ridge 20 which is substantially V-shaped when seen in cross-section and which is formed by threefold bending or folding of the rail 15. This leg preferably extends at right angles to the groove bottom 16, whereas the other leg 21 of the stiffening ridge 20 defines an obtuse angle with the fastening strip 17 and an acute angle with the leg which forms the side 19 of the lock¬ ing groove. On the other hand, the other side 22 of the groove defines with the groove bottom 16 an obtuse angle which is preferably smaller than the angle defined between the leg 21 of the stiffening flange and the fastening strip 17, and thus is inclined slightly out¬ wards, so that the width of the groove 14 will increase in a direction inwardly and outwards. The groove 14, however, may be formed so that its sides 19, 22 are substantially parallel to one another.

Each support rail includes a further generally V-section stiffening ridge 23 which extends in a direction oppo¬ site to the stiffening ridge 20 formed by one side of the locking groove, with the apex 24 of the V located in a fold 25 formed in the underside 13 of the platform 3 by bending the pallet beams 4, and on parallel support surfaces located on both sides of said stiffening ridge 23 and fastened to the fastening strip 17 and therewith to the platform 3, of which support surfaces the support surface 26 connects the groove side wall 22 with the stiffening ridge 23, whereas the support surface 27 extends into a fold 28 which is formed when bending the beam 4 and which preferably has a slightly upfolded edge part 29 which functions to fix the rail 15 to said fold.

In the case of the illustrated embodiment, each beam of the inventive loading pallet is provided with mutually spaced and downwardly open recesses 30 which are config- ured to allow the forks of a loader also to be inserted from the long sides of the pallet. Consequently, the illustrated embodiment of the inventive pallet has a so- called four-way construction, i.e. a construction with which the lifting forks can be inserted from all four directions. The upper defining surfaces 31 of respective recesses 30 in each beam 4 lie level with the support surfaces 26, 27 of the rail 15 which thus come into contact with the lifting forks and, as a result of the locking engagement of the stiffening ridge 23 of the rail in the fold 15, the support surfaces are supported so as to be able to withstand those loads to which they are subjected when the pallet is fully loaded.

When carried by lifting forks or tines inserted through the recesses or cavities 30, the illustrated pallet will rest on the support surfaces 26, 27 of the support rails, which thus distribute the load over a relatively wide area in a manner which is advantageous from the aspect of durability, and to some degree also to the upper defining surfaces 31 of the recesses in the outer side 32 of respective beams, said surfaces preferably being level support surfaces 26, 27 of the support rails in the manner earlier mentioned. The same weight distri- bution is achieved through the fastening strips 17 of the rails in the space 6 between the support beams 4, when these are wide enough, although this is not neces¬ sary from the aspect of mechanical strength. The fasten¬ ing strips 17 can thus be dimensioned to lie in mutual edge-to-edge abutment.

In accordance with the present invention, a number of impact absorbing, U-section cross-stays 33 are provided between the support beams 4 of the loading pallet for those beams which function as pallet legs. The cross- stays 33 are made from the same type of corrugated plate as the remainder of the pallet and have a width such as to include at least one crest 34 and two troughs or dales 35 or two crests 34 and one trough 35 and such that stays will not extend inwardly of the defining surfaces 31, 50 of the recesses 30 in the case of the present four-way loading pallet. When the inventive pallet is a two-way pallet, the cross-stays 33, on the other hand, may be made wider than shown in the accom¬ panying drawings, when the impact forces or loads to which the pallet can be subjected so demand or require. The cross-stays also function as a support for the pallet legs 4, and the number of stays provided will depend on the length of the pallet and may be greater or smaller than the three stays shown in the drawings, this latter number being suitable for pallets of standard lengths.

Each cross-stay 33 can be said to have an extended U- shape and includes two legs 36 and one intermediate member 37 which joins said legs. The legs 36, which are bent substantially at right angles to the intermediate member 37, have a height or vertical extension, measured from the underside 38 of the intermediate member 37, which equals the height or vertical extension of the inside 11 of a respective beam, and more specifically which equals the distance of the underside 39 of the beam to the free end 12 of its inside.

In the case of the illustrated embodiment of the inven- tive pallet, with which the first corrugation, as seen from one of the sides 7 of the pallet, is comprised of a crest 34 and next by a trough 35, the third of a crest 34, and so on, each cross-stay 33 includes at least two troughs 35 and an intermediate crest 34 which along the whole of its length along the legs of the cross-stay engages the trough 35 of the inside 11 of a respective beam, while the crests 34 of said inside 11 similarly engage the troughs 35 of the respective legs 36 of the cross-stay, as will be seen particularly from Figs 3 and 4. This mutual gripping engagement between the corru- gations of the support beams 4 and the corrugations of the cross-stays and the trapezoidal cross-section of the corrugations ensure positive locking of the cross-stays 33 with respective support beams 4 and provide an ulti¬ mate solution to the problem of mechanical strength and durability with pallets that are made metal plate, and particularly of corrugated plate, and also impart impact strength to the pallets and a long and useful life.

Each cross-stay 33 is also fastened to the pallet beams 4 by means of screws, shown in chain lines 46 in Fig. 3, which extend through the legs 36 of the cross-stay, the inside 11, and through the side 22 of the locking groove. The screws 46 are preferably self-tapping screws and function to hold each cross-stay 33 in place, such that the underside 39 of respective support beams and the underside 38 of respective cross-stays 33 lie in one and the same plane and enable the pallet to be readily transported on so-called roller paths. It should be noted here that the stiffening ridge 20 formed by the defining side 19 of the locking groove is much longer than the other defining side 22 of the groove. This facilitates insertion of the aforesaid screws and en¬ ables the stiffening ridges 20 to be given a relatively narrow dimension, so that the ridges will not encroach unduly on the space 6 for the lifting forks of the loader.

As shown in Fig. 7, the inventive loading pallet also includes tubular devices which have a "flat" oval or elongated cross-sectional shape, as shown in Fig. 7, within a part of the crests 34 of the load-carrying platform, and in each case each of the two outer crests and optionally each of one or more of the crests 34 lying therebetween is preferably provided with an indi¬ vidual tubular device 40. Each such tubular device 40 extends across the platform 3 within its individual crest 34 and out through holes 43 in respective corners 8. The holes 43 have generally the same cross-sectional shape as the tubular devices 40 and the devices 40 are open at each end thereof so as to receive a respective metal or fabric load-strapping band 42 by means of which the load can be secured on the pallet, should the need arise.

Each tubular device 40 is conveniently secured in its respective crest 34 by means of tags 41 formed at both ends of said device, said tags being bent backwards, downwards and upwards around the bottom and top defining surfaces 44 of respective holes 43, as shown in Fig. 3 for instance. Backward bending of tags 41 will also result in a rounded surface against which the load strapping band can lie at each end of a tubular device, as opposed to a sharp edge which would be likely to damage the strap as it is drawn through its respective tubular device 40.

One drawback with earlier known metal-plate pallets is that the friction generated by the load-carrying surface of the pallet is very low and a load placed on this surface will tend to slide. In order to overcome this drawback, at least the load-supporting part of the load-carrying platform 3 of the inventive pallet is provided with a friction-enhancing coating 44 of rubber granulate, which is adhesively bonded to said surfaces and the binder used is preferably an acrylate type binder. The present invention is not restricted to the described and illustrated embodiment thereof since modifications and changes can be made within the scope of the inven¬ tive concept as defined in the following claims.

Claims

1. A pallet comprising a load-carrying platform (3) which includes transverse stiffening ridges (2) and which is supported at least at its mutually opposing long edges or sides (5) by support beams (4) which extend perpendicularly to the stiffening ridges of the platform and which present therebetween a space into which lifting forks can be inserted from the sides of the pallet and which beams and which platform are made from corrugated metal plate, wherein the corrugations (2) form said platform stiffening ridges and extend along the sides of the support beams, and wherein the inside (11) of each such support beam forms a support leg which acts on the underside (13) of the platform, and wherein the end part (12) of respective legs that face towards the underside of the platform are locked in a generally perpendicular position in relation to the platform (3) in a locking groove (14) provided in a rail (15) mounted on the underside of the platform, c h a r a c t e r i z e d in that a number of beam- supporting cross-stays (33) are disposed between the beams (4) .

2. A pallet according to Claim 1, c h a r a c ¬ t e r i z e d in that the cross-stays are made of the same kind of metal plate as the remainder of the pallet.

3. A pallet according to Claim l or 2, σ h a r a c- t e r i z e d in that the cross-stays (33) have a U- shape, and in that the legs (36) of the stays are con¬ nected to the inside (11) of a respective beam (4).

4. A pallet according to any one of the preceding claims, c h a r a c t e r i z e d in that the under¬ side (38) of each cross-stay (33) lies in the same plane, or essentially the same plane as the underside (39) of respective beams (4).

5. A pallet according to any one of claims 2 to 4, wherein the plate corrugations comprise alternating crests and troughs, c h a r a c t e r i z e d in that each cross-stay (33) includes at least one crest (34) and troughs (35) located on each side thereof, or at least one trough (35) and crests (34) located on each side thereof for locking engagement with at least one trough (35) and two crests (34) or with at least one crest (34) and two troughs (35) on respective beams (4).

6. A pallet according to one or more of preceding claims 1-3, c h a r a c t e r i z e d in that the legs (36) of each cross-stay are connected to the inside (11) of respective beams (4) with the aid of screws (46), preferably with the aid of self-tapping screws.

7. A pallet according to claim 6, c h a r a c¬ t e r i z e d in that the screws (46) also extend through or are screwed into the distal wall (22) of the locking groove (14) in the support rail (15).

8. A pallet according to claim 7 in which each beam (4) includes a recess or cavity (30) for receiving lifting forks also from the long sides of the pallet, c h a r a c t e r i z e d in that said support rail (15) includes a strengthening ridge (23) which extends into a fold (25) in the underside of the platform at the junction to respective beams (4) and support surfaces (26, 27) on both sides of said strengthening ridge, said surfaces being located level with the upper defining surface (31) of a respective recess or cavity (30) to form a lifting-fork bearing surface.

9. A pallet according to any one of the preceding claims, c h a r a c t e r i z e d in that open-ended tubular devices (40) are provided within at least a part of the platform corrugations (2) for coaction with a strap to secure a load on the pallet.

10. A pallet according to any one of the preceding claims, c h a r a c t e r i z e d in that the pallet is provided with a friction-enhancing covering, at least on the load-carrying surfaces of the platform.