WO2001062611A1

WO2001062611A1 - A pallet construction

Info

Publication number: WO2001062611A1
Application number: PCT/SE2001/000416
Authority: WO
Inventors: Karl Johan Back
Original assignee: Karl Johan Back
Priority date: 2000-02-25
Filing date: 2001-02-26
Publication date: 2001-08-30
Also published as: AU4131301A; SE0000623D0; SE0000623L

Abstract

The present invention relates to a pallet construct with respect to pallets that are intended to carry goods and that include a load carrying upper part (11) which has a preferably unbroken surface, and a lower part (12) which is spaced from the upper part (11) and which rests against a supporting surface, and spacing elements (13) disposed between the upper part (11) and the lower part (12) of said pallet (10) and secured thereto in a manner such as to define between said spacing elements openings in which the forks of a forklift truck or like device can be inserted. According to the invention the spacing elements (13, 13') have disposed preferably on mutually opposing sides drilled holes (17) of which at least a part has internal threads and the upper pallet part (11) includes pre-drilled through-penetrating holes (14). The lower pallet part (12) includes drilled-through penetrating holes (15) that are identical to the through-penetrating holes in the upper pallet part (11) and each through-penetrating hole (14, 15) in the upper and the lower part (11, 12) of the pallet (10) has a relatively small and a comparatively large diameter, wherein the spacing elements (13, 13') are fastened to respective upper and lower partS (11, 12) of the pallet (10) by fastening devices (18) that include a cylindrical stem (19) provided with external threads, and a head part (20) whose perimeter is larger than the perimeter of the stem (19). The external threads of the stem (19) are adapted to co-act with the internally threaded part of respective spacing elements (13, 13') subsequent to inserting said stem into respective holes (14, 15); and the head part (20) of respective devices (19, 20) is adapted to rest in that part of the through-penetrating holes (14, 15) in the upper and lower parts (11, 12) of the pallet (10) that have the larger diameter.

Description

A pallet construction

The present invention relates to a pallet construction of the kind defined in the preamble of Claim 1.

Pallets of this kind are produced typically from wood, which provides an homogenous product. Such pallets, however, are heavy and cannot readily be moved when empty. The pallets are also bulky and the cost of transporting an empty pallet of this kind from a manufacturer to a consumer quite considerable. For this reason, a large number of pallet manufacturers are spread over their particular country at relatively short distances from respective users. The manufacture of such pallets also entails relatively many different manufacturing steps, and is relatively expensive. Millions of pallets are produced annually, resulting in a very large consumption of wood and therewith also in a depletion of natural assets.

The manufacture of disposable pallets from corrugated board has also been proposed. Although corrugated board is beneficial from the aspect of weight, such pallets have not been terribly successful, since they are found to be unable to withstand the harsh treatment to which they are often subjected by forklift trucks or forked trolleys. It is also necessary to cover the corrugated board with a liquid protective material, which has also been found to be expensive.

Examples of corrugated board pallets are found in GB-2 284 592 and EP 0 283 799 Al . VO 93/21076 teaches a pallet that includes a load carrying surface comprised of sheet material that has been folded to form a frame. The advantage of pallets of this latter kind is that they are light and have a weight which is markedly less than the weight of a typical wood pallet. As before mentioned, pallets of this former kind have the drawback of being unable to withstand the often harsh treatment to which they are subjected. It is necessary to surface treat the corrugated board to resist wet- ting, wherewith the cost scenario becomes less favourable. These pallets are also still relatively bulky and the transport costs of each individual pallet is relatively high. Moreover, the possibilities of being able to repair damaged pallets of this latter kind are very scarce indeed.

Regardless of the type of pallet concerned, a common fact is that all known pallets are scrapped as soon as a component has been broken, irrespective of whether this component is a load carrying surface or a spacer element.

The object of the present invention is to provide the pallet market with novel devel- opment options in the form of enhanced quality and improved economy.

In order to enable the reader to comprehend the situation more fully, reference is made to a market research carried out across the US pallet market during the year 1995 and reported in the US journal Modern Materials Handling and National Wooden Pallet and Container Association (NWPCA). It is stated in this report that there were 1 800 000 000 pallets in circulation and in use and 28 000 manufacturing companies involved in the manufacture of pallets during this period. Over 500 million pallets were newly manufactured during the year 1995.

Number of wooden pallets in percent 92% Number of plastic pallets in percent 5% Number of pallets from other materials 3%.

These 92% wooden pallets required 40% of felled hardwood in the USA.

All pallet spacers are comprised of wood and all planks are nailed in mutually spaced relationship with at least 72 and at maximum 96 nails per pallet.

The use of nails renders repair of the pallets uneconomical. As a result, the quality of the pallets progressively degenerates and they are normally scrapped after being used one or two times. This wear and discard policy is disruptive to the environment. Working on the basis that two pallets will be newly manufactured per inhabitant and year in the western world, and that within the next 20 years the need in developing countries will rise to one pallet per inhabitant, there is obtained the giddy total of 7 billion pallets each year. Such a high requirement cannot be satisfied in India, China, etc. The result will be an uneconomic transport system i these countries.

Applicant, who is well versed in different pallet techniques, has observed that the pallets, regardless of type, will be demolished/damaged to a very large extent when handled by forklift trucks, which is the most common means used to shift pallets. Naturally, it is the spacers located between the upper, load carrying plane of the pallet and its bottom part that lies against a supportive surface that will be broken during handling of the pallet and therewith render the pallet unusable. A pallet that has been broken or demolished in this respect is not considered by the industry to be worthy of repair, and consequently the pallet is scrapped and replaced with a new one. When considering the enormous number of pallets that are manufactured/used annually and the costs entailed by these pallets, it seems that scrapping of a pallet as a result of the demolition of a spacing element for instance is a waste of resources.

After careful consideration, applicant has realised that an existing pallet pool can be utilised more efficiently with the aid of simple means, and therewith provide a way in which damaged or unusable components, such as spacing elements for instance, can be restored, in principle regardless of pallet construction. The solution to the aforesaid problem is set forth in the characterising clause of the accompanying Claim 1.

Thus, by allowing the spacing elements between the upper and the lower part of the pallet to be comprised of a body that has on opposing sides a drilled hole that has an internal thread with which an element provided with external threads can be caused to co-act, there can be obtained a simple, exchangeable screw-like fastening device. Pre-formed holes in the upper and lower part of the pallet facilitate the exchange or replacement of a damaged spacing element. It is estimated that the present invention will reduce the requirement of newly manufactured pallets by 30-50% on a yearly basis. A useful pallet life of 5-10 years is conceivable as a result of the inventive pallet construction.

In a further embodiment of the inventive pallet construction, the screw fastening device is applied so that its upper part lies flush with or generally flush with the sur- face of respective upper and lower pallet parts, or at least so that the main part of the fastening device does not project out beyond said respective surfaces.

When the components of a thus constructed pallet are formed from synthetic material, e.g. a commercial plastic, there is obtained a product that cannot only be re- paired relatively cheaply but that can also be washed clean and therewith retain an hygienic product.

The invention will now be described with reference to an exemplifying embodiment and with reference to the accompanying drawings. The description is also concerned with proposals for preferred embodiments of the inventive arrangement.

Figure 1 is an exploded view of a pallet that includes a spacing element according to the invention;

Figure 2 is a vertical sectioned view through a pallet provided with the improved spacing elements;

Figure 3 is a side view of the preferred screw fastening device that holds together the upper, load carrying part of the pallet and its lower part, with the aid of a spacing element according to the invention; and

Figure 4 illustrates an alternative embodiment of an inventive construction in which the illustrated spacing element comprises a hollow body. The pallet 10 shown in Figure 1 is comprised of an upper part 11, the load carrying plane or part, which is preferably comprised of a complete sheet-like product made of an appropriate material and having a typical thickness of between 6 and 20 mm. Although the material may be of any suitable kind, it is preferred that the material is a plastic product, although any other sheet material may, of course, be used. Alternatively, the upper load carrying part 11 of the pallet 10 may consist of mutually spaced slats of material of the aforesaid typical thickness, similar to the case of conventional wooden pallets.

As will be apparent from Figure 1, the bottom plane (or part) of the pallet 10 may be comprised of mutually spaced slats 12, said plane 12 lying, of course, against an abutment, not shown. The material from which the slats 12 are made will preferably be the same material as that from which the upper surface or plane 11 of the pallet 10 is made.

The upper plane 11 of the pallet is joined conventionally to the lower plane 12 by means of spacing elements 13, which are each mounted on the upper side of the lower plane 12 and caused to abut the upper plane or part 11 of the pallet 10. As is conventional, the spacing elements are disposed in mutually spaced relationship so as to form therebetween openings into which the forks of a typical forklift truck can be inserted for movement of the pallet 10.

The spacing elements 13 are typically nine in number and are positioned so that they can uniformly take-up the weight of the load on the upper load carrying plane 11, in the way shown in Figure 1 for instance.

The unique features of the present invention lie in the particular design of the spacing elements 13 and the manner in which they are fastened to respective upper and lower planes 11 and 12 of the pallet 10, this being shown in Figure 2. Figure 2 is a vertical section view that shows the upper pallet plane 1 1 provided at pre- determined positions (or having previously been provided) with a number of through-penetrating cylindrical holes 14 having an upper part of comparatively large diameter and continuing with a smaller diameter. All penetrating holes in the loading plane 11 are mutually identical.

Similarly, the lower part of the pallet 10 (in the illustrated case the elongate slats 12) is provided with (or has previously been provided with) through-penetrating cylindrical holes 15 at pre-determined locations, wherein each of said holes has a comparatively large and a smaller hole diameter. The transition of the cylindrical holes 14, 15 from a large diameter to a smaller diameter is effected by a ring-shaped abutment 16.

The spacing elements 13 have typically a square shape and a standard height. Each individual spacing element 13 has either a through-penetrating and centrally disposed drill hole 17 that includes an individual thread, or blind holes drilled centrally on opposing sides and provided with internal threads.

When assembling a pallet 10 comprising the components illustrated in Figure 1, the spacing elements 13 are positioned so that central drill holes 17 will be in alignment with the holes 15 in the lower part of the pallet 10 and with the holes 14 in the upper part of said pallet. A fastening device 18 is then inserted into typically the hole 14 in the upper plane 1 1 of the pallet 10. The fastening device 1 1 includes a stem 19 provided with external threads, and a head 20. The stem 19 of the fastening device 18 is typically dimensioned to enable it to be pressed-in through the hole 14 in the upper plane 1 1 of the pallet 10 and then turned for thread-co-action with the threaded hole in an underlying spacing element 13. In order to facilitate rotation of the fastening device 18, the top side of said device (its head 20) is provided, e.g., with an internal groove in the form of a square or hexagonal recess, or with some other conventional shape. In the former case, the fastening device 18 is normally turned with the aid of a square-ended spanner or an Allen-key, and with the aid of a conventional screw driver in the other case.

Assembly of the pallet is continued until all spacing elements 13 have been joined to the upper and lower planes 11, 12 of the pallet 10, wherewith the head 20 of respective fastening devices 18 will lie generally flush with respective surfaces of the upper and lower parts of the pallet, in other words the bottom surface of the head 20 is brought into abutment with the seating 16 in respective holes 14, 15.

The threaded stem 19 of the fastening device 18 will then have positive thread co- action with the internally threaded hole in the spacing element 13 and cannot be loosened unintentionally.

The spacing element 13 may typically be made of a suitable plastic material. The spacing element may be a solid body or a hollow body, or may comprise two mutually joined hollow bodies that each have a through-penetrating hole located on their mutually opposite sides and provided with internal threads. The pallet 10 is assembled in the aforedescribed manner, regardless of the design of the spacing element.

Figure 4 illustrates an alternative embodiment of a pallet construction according to the invention, in which the spacing element 13 is comprised of a hollow body, referenced 13' in Figure 4. In this embodiment, the interior of the hollow body 13' may be delimited by three vertical load-bearing walls which are connected top and bottom to horizontal plates in which centrally disposed, through-penetrating holes are provided, said holes having internal threads, and a fourth vertical wall 13" which may either be removable or be a door-like arrangement that will enable a counter nut (not shown) to be fitted to the threaded part at the bottom of the fastening device 18 projecting out from the interior of the hollow body 13', therewith further ensuring that the connection between spacing element 13 and respective upper and lower pallet planes cannot be released unintentionally. Practical tests have shown that the diameter of the head 20 of the fastening device 18 shall be approximately twice as large as the diameter of the stem 19, these fastener parts having a size of 50 and 24 mm respectively. The thickness of the head 20 will conveniently be half the thickness of the respective pallet parts 11 and 12.

Analogously, the hole orifice 14 of the load carrying part 1 1 has a countersink of the same diameter as the head 20 of the fastening device 18 and a depth corresponding to the longitudinal extension of the head 20.

In an optimum embodiment, each pallet component (upper plane, lower plane, spacing elements, fastening devices) can be replaced simply and quickly. In addition, when the pallet components are comprised of plastic material, there is obtained a washable, hygienic product at a cost that is considerably lower than a conventional wooden pallet for example. Obviously, the use of a suitable synthetic material will enable the weight of an empty pallet to be greatly reduced in comparison, and therewith enable the pallet to be handled more easily.

It will be obvious to the person skilled in this art that the form of each component of the pallet 10 may be freely chosen, and that the aforedescribed and illustrated em- bodiments do not limit the scope of the invention but can be modified within the scope of the accompanying claims.

Claims

1. A pallet construction relating to pallets that are intended to carry goods and that include a load carrying upper part (11) that has a preferably unbroken surface, and a lower part (12) which is spaced from the upper part (11) and which rests against a supporting surface, and spacing elements (13) disposed between the upper part (11) and the lower part (12) of said pallet (10) and secured thereto in a manner such as to define between said spacing elements openings in which the forks of a forklift truck or like device can be inserted, characterised in that the spacing elements (13,13') have disposed preferably on mutually opposing sides drilled holes (17) of which at least a part has internal threads; in that the upper pallet part (11) includes pre-drilled through-penetrating holes (14); in that the lower pallet part (12) includes drilled- through penetrating holes (15) that are identical to the through-penetrating holes in the upper pallet part (11); in that each through-penetrating hole (14,15) in the upper and the lower part ( 11 , 12) of the pallet ( 10) has a relatively small and a comparatively large diameter; in that the spacing elements (13, 13') are fastened to respective upper and lower parts (11,12) of the pallet (10) by fastening devices (18) that include a cylindrical stem (19) provided with external threads, and a head part (20) whose perimeter is larger than the perimeter of the stem (19); in that the external threads of the stem (19) are adapted to co-act with the internally threaded part of respective spacing elements (13,13') subsequent to inserting said stem into respective holes (14,15); and in that the head part (20) of respective devices (19,20) is adapted to rest in that part of the through-penetrating holes (14,15) in the upper and lower parts (11,12) of the pallet (10) that have the larger diameter.

2. An arrangement according to Claim 1, characterised in that the fastener head part (20) having said larger perimeter is orientated so that the upper surface of said head part will lie at least flush with the surface of respective upper and lower pallet parts (1 1,12) subsequent to rotation of said fastening device.

3. An arrangement according to Claim 1 and 2, characterised in said head part (20) of the fastening device includes means for co-action with a tightening tool, e.g. a square-edge spanner or a screwdriver.

4. An arrangement according to Claim 1 , characterised in that the spacing elements (13) have a generally square shape.

5. An arrangement according to any one of Claims 1 or 3, characterised in that the spacing elements (13) have a shape that deviates from a square shape, e.g. an essen- tially cylindrical shape.

6. An arrangement according to any one of Claims 1, 3 or 5, characterised in that the spacing elements (13) are made of a synthetic material.

7. An arrangement according to any one of Claims 1-6, characterised in that the head part (20) of the fastening device (18) is adapted so that its under surface will lie against a shoulder (16) in respective holes in the upper and lower parts (11,12) of the pallet (10).

8. An arrangement according to any one of Claims 1, 4, 5 or 6, characterised in that the spacer element is a hollow body (13').

9. An arrangement according to Claim 8, characterised in that the hollow body (13') is a square body; and in that means are provided for access to the interior of the hollow body (13') (Figure 4).