Prior Art From SE-C-508 874 a pallet is previously known, said pallet being manufactured from thermoplastic. The pallet comprises a hollow load carrying portion and three hollow main structure elements. The load carrying portion and the main structure elements are formed in separate moulds. When the load carrying portion and the main structure elements are manufactured they are subjected to cooling and after- shrinkage, which normally lasts for one day or a few days, before they are assembled to a unit. For this purpose the load carrying portion and the main structure elements are equipped with a number of planar joining surfaces that are heated by being brought into contact with a heated plate. The load carrying portion and the main structure elements are then urged together while the thermoplastic of the joining surfaces still is hot, the load carrying portion and the main structure elements being welded together to form a unit. In this connection it should be observed that the load carrying portion and the main structure elements are connected to each other by means of planar, welded surfaces.

From DE-OS-27 33 457 a pallet of plastic is previously known, said pallet being manufactured by joining two pre- fabricated elements. A spigot shaft of one element cooperates with an opening of the other element, said elements may either be screwed together or glued together. It seems that the spigot shaft and the opening only have the function to facilitate the assembling of the elements, i. e. they have in principle no load carrying ability.

Objects and Features of the Invention A primary object of the present invention is to present a pallet that is manufactured from a number of pre-fabricated

elements of a plastic material, said pallet in assembled condition having excellent properties as regards load carrying ability, e. g. torsional rigidity and bending rigidity. These properties of the palLet are achieved by bringing the pre- fabricated elements to cooperate with each other in a favourable way.

A further object of the present invention is that if any element of the pallet is damaged, said element may be exchanged since the portions of the pallet are detachably joined to each other.

Still an object of the invention is that the entire pallet may be recycled in a simple way since preferably all the elements of the pallet are manufactured from a plastic material.

At least the primary object of the pallet is achieved by means of a pallet that has been given the features of the appending independent claim. Preferred embodiments of the invention are defined in the dependent claims.

Brief Description of the Drawings Below embodiments of the invention will be described, reference being made to the accompanying drawings, where: Figure 1 shows a perspective view, inclined from above, of a first embodiment of a pallet according to the present invention; Figure 2 shows a perspective view, inclined from below, of the pallet according to figure 1; Figure 3 shows in perspective an exploded view, inclined from above, of the pallet according to figure 1; Figure 4 shows in perspective an exploded view, inclined from below, of the pallet according to figure 1; Figure 5 shows a section through one of the supporting means of the pallet and an adjoining portion of the pallet; Figure 6 shows in perspective an exploded view, inclined from above, of an alternative embodiment of a pallet according to the present invention; Figure 7 shows in perspective an exploded view, inclined from below, of the palate according to figure 6; and

Figure 8 shows a section through one of the supporting means of the pallet and an adjoining portion of the pallet according to the alternative embodiment.

Detailed Description of Preferred Embodiments of the Pallet According to the Present Invention The pallet 1 shown in figures 1 and 2 consists of a number of pre-fabricated elements that in assembled state forms the pallet 1 according to figures 1 and 2. In order to describe the structural design of the pallet 1 more in detail, reference is being made to figures 3-5.

As is evident from the exploded views according to figures 3 and 4 the pallet 1 according to the present invention comprises a number of pre-fabricated elements. Thus the pallet according to the present invention comprises a rectangular, upper load carrying element 3 and a rectangular, lower load carrying element 5, said load carrying elements 3, 5 having a corresponding basic shape in their respective main planes.

At the side facing towards the lower load carrying element 5 the upper load carrying element 3 is equipped with a number of first sleeves 7 that in the show embodiment are cylindrical, the centre axes 6 of the cylinders having an extension substantially perpendicular to the main plane of the upper load carrying element 3. The upper load carrying element 3 is equipped with a number of first recesses 8 that are concentric relative to the centre axes 6, a through going hole being provided in the bottom of each recess 8, see figure 5, each cylindrical sleeve 7 having a first recess 8.

As is evident from figure 4 the upper load carrying element 3 is also equipped with a number of first reinforcement ribs that on one hand extend along the edges of the upper load carrying element 3 and on the other hand extend inside said edges in a bar pattern, the first reinforcement ribs 9, located inside the edges, intersecting each other at right angles. The planes of the first reinforcement ribs 9 have an extension substantially perpendicular to the main plane of the upper load carrying element 3. In the shown embodiment the height of the first reinforcement ribs 9, i. e.

their extension from the main plane of the upper load carrying element 3 is smaller than the corresponding height of the sleeves 7.

The lower load carrying element 5 is equipped with a number of second sleeves 10 that in the shown the embodiment are cylindrical and have an extension on both sides of the main plane of the lower load carrying element 5. In correspondence to the upper load carrying element 3 the centre axes of the second sleeves 10 have an extension substantially perpendicular to the main plane of the second load carrying element 5. The first and second sleeves 7 and 10 respectively have such a mutual location on the respective load carrying element 3,5 and such a mutual diameter relation that they may be telescopically received in each other by a relatively tight slide fit, see figure 5, when the load carrying elements 3,5 are assembled in order to form the pallet 1 according to the present invention. This means that when said first and second sleeves 7 and 10 respectively have assumed the position according to figure 5 they will cooperate with each other when the pallet 1 according to the present invention is subjected to various loads during its use. In the shown embodiment the second sleeves 10 have a larger diameter than the first sleeves 7, and more precisely the internal diameter of the second sleeves 10 are somewhat larger than the external diameter of the first sleeves 7 in order to effect said relatively tight slide fit mentioned above. As is evident from figure 5 the first and second sleeves 7 and 10 respectively have essentially equal height or axial extension.

As is evident from figure 3 the lower load carrying element 5 is also equipped with a number of second reinforcement ribs 11 that create rectangles around the portion of the second sleeves 10 that are located on the side of the second load carrying element 5 that faces towards the first load carrying element 3. The height of the second reinforcement ribs 11 is essentially the same as the height of the first reinforcement ribs 9 and in assembled position of the elements of the pallet 1, see figure 5, the first and second reinforcement ribs 9 and 11 respectively will overlap each other with a relatively tight slide fit. It is realised

that the location of the first and second reinforcement ribs 9 and 11 must be coordinated in such a way that they do not interfere with each other when the position according to figure 5 is assumed, i. e. when the elements of the pallet 1 are assembled to a pallet 1 ready to use.

The pallet 1 according to the present invention includes in the shown embodiment also three main structure elements 12.

Said main structure elements 12 have each three first projections 13 that are cylindrical, the centre axes 6 of the cylinders having an extension substantially perpendicular to the main plane of the main structure elements 12. The first projections 13 have a diameter of the same magnitude as the width of the main structure elements 12. A first cylindrical projection 13 is provided at the opposite ends of each main structure element 12 and an intermediate first projection 13 is also present on each main structure element 12. The mutual distance between the projections 13 is in principle the same and also in coincidence with the mutual distances between the first and the second sleeves 7 and 10 respectively in the longitudinal direction of the pallet 1. Preferably, the first projections 13 are integral with the main structure elements 12. As is most evident from figure 5 the first projections 13 are equipped with an end wall 14 facing away from the main structure elements 12. Said end wall 14 is equipped with a centrically located, through going hole 15, whose function will be explained below. When assembling the elements of the pallet 1 the first projections 13 will be received within the first sleeves 7, see figure 5, i. e. the external diameter of the first projections 13 should be somewhat smaller than the internal diameter of the first sleeves 7 in order to achieve a relatively tight slide fit between the first sleeves 7 and the first projections 13. As is evident from figure 5 the first projections 13 have a height that is essentially smaller than the height of the first and second sleeves 7 and 10 respectively.

The pallet 1 according to the present invention also comprises means to connect the elements described above. Said means constitutes in the shown embodiment so-called tubular screws that on one hand includes a screw 16 having an

externally threaded portion 17, see figure 5, and a head 18 and on the other hand an internally threaded sleeve 19 that at one end is equipped with a disc shaped means 20 that constitutes an abutment when the connecting means are activated. As is most evident from figure 5 the disc shaped means 20 has a certain height, said height in principle corresponding to the internal height of the first projection 13. In the embodiment according to figure 5 the disc shaped means 20 is hollow. Preferably, the disc shaped means 20 is equipped with a recess 21 at the side facing away from the sleeve 19, see especially figure 5, said recess 21 being concentric relative to the sleeve 19. As is evident from figure 5 the disc shaped means 20 is also equipped with grooves 22 on its upper side, said grooves cooperating with tongues 23 of the end wall 14 in order to prevent rotation of the sleeve 19 when the tubular screw is tightened.

Assembling of the elements of the pallet 1 according to the present invention to an operating pallet 1 is carried out in the following way. The upper load carrying element 3 and the lower load carrying element 5 are assembled and the first sleeves 7 are telescopically received in the second sleeves 10, see figure 5, as well as a the first reinforcement ribs 9 and the second reinforcement ribs 11 overlapping each other with a relatively tight slide fit in the way that is disclosed in figure 5, i. e. said reinforcement ribs 9 and 11 respectively form a kind of box structure. The main structure elements 12 are also assembled with the load carrying elements 3 and 5 respectively, said first projections 13 being telescopically received within the first sleeves 7.

In order to connect the load carrying elements 3,5 and the main structure elements 12 to each other in a satisfying way the means described above are attached in order to keep said elements together. The sleeve 19 is inserted in the through going hole 15 of the end wall 14 of the first projections 13. In this connection the sleeve 19 is inserted so far that the disc shaped means 20 will abut the end wall 14 and also the grooves 22 of the disc shaped means 20 will engage the tongues 23 of the end wall 14. The screw 16 is now introduced through the first recess 8/the threw going hole and

the threaded portion 17 of said screw 16 is received in the internally threaded sleeve 19. By tightening the screw 16 a safe and reliable connection is effected of the elements of the pallet 1 according to the present invention.

As is evident from figure 5 the head 18 of the screw 16 extends somewhat above the upper limiting surface of the upper load carrying element 3. The purpose of this arrangement is that said projecting portion of the head 18 of the screw 16 is brought to cooperate with the recess 21 of the disc shaped means 20. Thereby, it is facilitated, in connection with stacking of pallets 1 according to the present invention, that these pallets are directly above each other, i. e. the pile does not incline in any direction.

The telescopic cooperation, described above, by means of a tight slide fit of on one hand the first, second sleeves 7, 10 and the first projection 13 and on the other hand the first and second reinforcement ribs 9,11 brings about that the pallet 1 according to the present invention has an extremely satisfying load carrying ability, especially as regards bending stresses and/or tortional stresses.

It should also be stressed that the cylindrical design of the sleeves 7,10 and the first projection 13 is due to the fact that if the second sleeves 10, having an outmost location, come into contact with the arms of a fork truck in connection with handling of a pallet 1 according to the present invention the cylindrical shape brings about that the rounded ends of said arms more easily slide relative to said cylindrical second sleeves 10, and thereby the risk is reduced of having the second sleeves 10 damaged in connection with handling of the pallet 1 according to the present invention.

The alternative embodiment, shown in figure 6, of a pallet 1'according to the present invention has in assembled condition a design that to a very high degree coincides with the embodiment according to figures 1-5. For that reason the alternative embodiment of a pallet 1'is not shown in assembled condition but reference is made to figures 1 and 2.

In figures 6 and 7 two exploded views are shown in perspective of said alternative embodiment of a pallet 1'that comprises a rectangular, upper load carrying element 3'and a

rectangular, lower load carrying element 5', said load carrying elements 3', 5'having a corresponding basic shape in their respective main planes.

As is most evident from figure 7 the upper load carrying element 3'is equipped with a number of second projections 7' that generally are cylindrical and have an essentially lower height than the corresponding sleeves 7 of the embodiment according to figures 1-6. The second projections 7'are solid and preferably manufactured from the same material as the rest of the load carrying element 3'. In the area of said second projections 7', more precisely in the centre of said second projections 7', first recesses 8'are provided and a through going hole is provided in the bottom of said first recesses 8', see figure 8. Centre axes 6'extend in the centre of the second projections 7', said centre axes 6'having an extension substantially perpendicular to the main plane of the upper load carrying element 3'. The second projections 7'are also equipped with a circumferential shoulder 24', the importance of which will be explained below in connection with the assembling of the different elements of the pallet 1'.

As is evident from the exploded views according to figures 6 and 7 a reinforcement element 4'is provided between the load carrying elements 3'and 5', said reinforcement element 4'being equipped with a number of first reinforcement ribs 9'that create a bar pattern where the reinforcement ribs 9'intersect each other at right angle. The reinforcement ribs 9'have a perpendicular extension relative to the main planes of the load carrying elements 3'and 5'when said elements are assembled. First holes 25'are provided in the area of certain intersection points between the first reinforcement ribs 9', the function of said holes 25'will be explained below.

The lower load carrying element 5'constitutes in principle a sheet that is provided with a number of second holes 26', the function of which will be explained below. The centre axes 6'are located in the centre of the second holes 26'.

As is evident from figures 6 and 7 the pallet according to the alternative embodiment comprises also second sleeves

10'that constitute separate elements in the shape of cylinders. How said second sleeves 10'cooperate with the adjoining elements of the pallet according to the present invention is evident from the description below.

In the pallet 1'according to the present invention three main structure elements 12'are included. Said main structure elements 12'each have three first projections 13' that are cylindrical and the centre axes 6'of the cylinders have an extension essentially perpendicular to the main plane of the main structure elements 12'. A first projection 13'is provided at opposite ends of each main structure element 12 and an intermediate first projection 13'is also present on each main structure element 12. The mutual distance between the projections 13'is in principle the same and also in coincidence with the mutual distances between the second sleeves 7'in the longitudinal direction of the pallet 1'.

Preferably, the first projections 13'are solid and integral with the main structure elements 12', i. e. preferably of the same material as the main structure elements 12'. Each first projection 13'is equipped with a centrically located, through-going hole 15'having a third recess 27'. The function of the hole 15'will be explained below. Besides, each first projection 13'is equipped with a circular, circumferential groove 28', whose function also will be explained below. Both the projections 7'and 13'as well as the second sleeves 10'have a diameter of the same magnitude.

When assembling the elements of the pallet 1'the upper load carrying element 3', the reinforcement element 4'and the lower load carrying element 5'are initially joined to each other. Since said elements preferably consist of plastic, see below, they may be assembled by different techniques. In exemplifying and non-restricting purpose mirror welding, hot melt adhesion and vibration welding may be mentioned. When the parts of the load carrying element are assembled in a proper way assembling of the other elements of the pallet 1' is effected. In this connection the upper ends of the second sleeves 10'are brought to abut the shoulders 24'of the second projections 7', see figure 8, and the lower ends of the

second sleeves 10'are received in the grooves 28'of the first projections 13'.

The pallet 1'according to figures 6-8 comprises also means to connect the elements described above. Said means constitute in the shown embodiment so-called tubular screws that on one hand comprises a screw 16'having an externally threaded portion 17', see figure 8, and a head 18'and on the other hand an internally threaded sleeves 19'that at one end is provided with a disc shaped means 20'that constitutes an abutment when activating the connecting means. As is most evident from figure 8 the disc shape means 20'has a certain height, said height in principle coinciding with the internal height of the third recess 27'of the first projection 13'.

In the embodiment according to figure 8 the disc shape means 20'is solid. At the side facing away from the sleeve 19 the disc shape means 20'is preferably provided with a second recess 21', see especially figure 8, that is provided concentrically relative to the sleeve 19'. As is evident from figure 8 the disc shape means 20'is provided with pins 23' that cooperate with recesses 22'of the first projection 13' in order to prevent rotation of the sleeve 19'when tightening the tubular screw. In order to join the projections 7', 13' and the second sleeves 10'to each other in a satisfying way the means described above are applied in order to keep said elements assembled. Thus, the sleeve 19'is inserted in the through going hole 15'of the first projections 13'. Thereby, the sleeve 19'is inserted that far that the disc shaped means 20'will abut the bottom of the third recess 27', and also the recesses 22'of the first projection 13'will engage the pins 23'of the disc shaped means 20'. The screw 16'is inserted through the first recess 8'/the through going hole and the threaded portion 17'of said screw 16'is received in the internally threaded sleeve 19'. By tightening the screw 16'a safe and reliable connection of the elements of the pallet 1' according to figures 6-8 is provided. In this connection it should be pointed out that the guided cooperation between the groove 28'and one end of the cylindrical second sleeve 10'as well as the guided cooperation between the shoulder 24'of the second projection 7'and the other end of the second sleeve

10'brings about that the torsional rigidity and the strength of the pallet 1'become extremely good.

As is evident from figure 8 the head 18'of the screw 16'extends somewhat above the upper limiting surface of the upper load carrying element 3'. The purpose of this arrangement is that in connection with stacking of pallets 1' said projecting portion of the head 18'of the screw 16'is cooperating with the second recess 21'of the disc shaped means 20'of a pallet 1'located above. Thereby it is facilitated, in connection with stacking of pallets 1', according to figures 6-8, that these pallets 1'are located exactly above each other, i. e. the pile is not inclined in any direction.

The pallets 1; 1'according to the present invention, preferably completely manufactured from plastic, and in exemplifying and non-restricting purpose it may be mentioned that HD-polyeten has turned out to be a suitable plastic, said plastic preferably being recycled and W-stabilized. It should also be emphasised that within the scope of the invention it is feasible that the means for connecting the elements of the pallets 1; 1'may for instance be manufactured from a different material than plastic, e. g. metal. In this connection it should also be mentioned that even if said means for connecting the elements of the pallets 1; 1'are manufactured from plastic, said means may be manufactured from a different type of plastic than for instance the load carrying elements 3; 3'and 5; 5'. The reason therefore is of course that the special forces that for instance a thread connection in plastic is subjected to demand a special plastic material.