EP2357141B1

EP2357141B1 - A pallet

Info

Publication number: EP2357141B1
Application number: EP10461501A
Authority: EP
Inventors: Leslaw Becker
Original assignee: Becker Sp Zoo
Current assignee: Becker Sp Zoo
Priority date: 2010-02-11
Filing date: 2010-02-11
Publication date: 2013-01-02
Anticipated expiration: 2030-02-11
Also published as: EP2357141A1; ES2401675T3; PL2357141T3

Description

The present invention relates to construction of pallets.
Pallets are popular means for supporting loads to be transported or racked. The most popular type of pallets are wooden pallets, which have some disadvantages, such as heavy weight and short lifetime. Some of the disadvantages are overcome by plastic pallets, which can be lighter and more durable. However, the currently known plastic pallets present a number of other disadvantages.
A European patent application EP2067708 "Pallet" discloses a plastic pallet which has a load support platform and feet disposed under the platform. In order to improve the mechanical strength of the pallet, it is provided at the lower ends of the feet with elongate runners, which unite the feet within one row. The load support platform has a substantially planar and smooth upper side, while its lower side includes a reinforcing honeycomb structure. One problem which applies to such type of pallet is that when the pallet is handled by a pallet jack, also known as a pallet truck, the trail wheels located near the ends of the fork arms of the pallet jack may damage the elongate runners if the pallet jack is handled incorrectly. The pallet with damaged elongate runners loses its mechanical properties and dimensional stability, thus becoming unusable.
A US patent application US2009/0293776 "Pallet (Load Carrier)" discloses a plastic pallet provided with a plurality of hollow feet at its underside, wherein at least one of the feet, e.g. the central feet, has a length predominantly corresponding to the length or width of the pallet. Due to the fact that the pallet does not have elongate runners, it is less prone to damage by a pallet jack. However, the mechanical strength of the pallet is lower as compared to pallets having elongate runners. Since the pallet is made of a solid piece of plastic, the plastic should be relatively stiff in order to provide good mechanical strength. However, the use of stiff plastic makes the pallet fragile and leads to increased number of damages caused by impact, for example impact by fork lifts during handling of the pallet. Furthermore, such pallet cannot be used with automatic production and warehouse lines having micro switch sensors configured to detect elongate runners.
A German patent application DE4336469A1 presents a pallet made substantially of plastic, comprising a load support platform from which a plurality of parallel rows of feet protrude downwards, wherein the load support platform comprises a substantially closed top surface and a substantially closed bottom surface joined by internal ribbing. The internal ribbing comprises plastic ribs and a steel frame positioned between the plastic ribs, in grooves formed perpendicularly to the direction of plastic ribbing.
The aim of the present invention is to provide a plastic pallet which can be used for heavy loads and which has a construction that minimizes the risk of damaging the pallet during use.
The object of the invention is a pallet made substantially of plastic, comprising a load support platform from which a plurality of parallel rows of feet protrude downwards, wherein the load support platform comprises a substantially closed top surface and a substantially closed bottom surface joined by internal ribbing, wherein the internal ribbing comprises a plurality of steel-reinforced plastic ribs inside which steel rods are positioned, the steel-reinforced plastic ribs extending along the direction of the rows of feet.
The load support platform can be made of a top ribbed plate comprising the substantially closed top surface and a bottom ribbed plate comprising the substantially closed bottom surface from which the plurality of rows of feet extend downwards, wherein at least part of the ribs of the top ribbed plate are welded with at least part of the ribs of the bottom ribbed plate to form the load support platform.
The internal ribbing may comprise a plurality of longitudinal ribs parallel to the rows of feet and a plurality of transverse ribs perpendicular to the rows of feet.
The top ribbed plate and/or the bottom ribbed plate may have a longitudinal rib reinforced by a steel rod located between each pair of neighbouring rows of feet.
The bottom surfaces of the feet within at least one row can be separate from each other.
The feet within at least one row can be connected by skids, which can be detachably connected at the bottom surfaces of the feet.
The skids can be connected to the feet by snap-type fasteners.
Each skid may comprise an elongate member having a flat bottom surface and protrusions extending upwards from the end portions of the elongate member, the protrusions configured to be snapped into openings in neighbouring feet such as to position the flat bottom surface of the skid coplanarly with the bottom surfaces of the feet.
The elongate members may have a central flat top surface and side edges raised above the central flat top surface.
The width of the skids can be narrower than the width of the feet to which the skids are connected.
The vertical edges of the feet can be chamfered.
The substantially closed bottom surface can have chamfered edges.
The substantially closed top surface can have openings located above each foot.
The plastic can be impact resistant polyethylene.
The load support platform can have a thickness of at least 50 mm and the internal ribbing can have a thickness of at least 8 mm.
The invention is shown on a drawing, in which:

Figs. 1A and 1B present an embodiment of a pallet according to the invention viewed from the top and from the bottom, respectively.
Figs. 2A and 2B present a top ribbed plate viewed from the top and from the bottom, respectively.
Figs. 3A and 3B present a bottom ribbed plate viewed from the top and from the bottom, respectively.
Figs. 4A and 4B present a skid viewed from the top and from the bottom, respectively.
Figs. 5A, 5B and 5C present a top view, a side view in the length direction and a side view in the width direction of the pallet, respectively.

The pallet according to the invention is made substantially of plastic, i.e. most of the elements of the pallet are plastic and only some of the elements are reinforced by steel. The pallet comprises a load support platform 101, from which a plurality of parallel rows of feet 151-153; 154-156; 157-159 protrude downwards. In the presented embodiment, three rows of three feet in each row are shown. The direction parallel to the direction of the rows of feet will be referred to as the length direction, and the direction perpendicular to the direction of the rows of feet will be referred to as the width direction. The pallet is supposed to be lifted by inserting fork arms perpendicularly to the direction of the rows of feet.
The load support platform 101 comprises a substantially closed top surface 121 and a substantially closed bottom surface 141 joined by internal ribbing, i.e. at least part of the internal ribbing extends from the top surface 121 to the bottom surface 141. The top surface 121 is substantially closed, i.e. most of the top edges of the internal ribbing are joined together by a continuous layer of the top surface 121. The bottom surface 141 is also substantially closed, i.e. most of the bottom edges of the internal ribbing are joined together by a continuous layer of the bottom surface 141. Furthermore, the internal ribbing comprises a plurality of steel-reinforced ribs 111, 112, 131, 132 extending along the direction of the rows of feet 151-153; 154-156; 157-159, therefore providing additional strengthening in the length direction. The load support platform has therefore a closed box construction, which by itself, without the need for additional strengthening at the bottom surface of the feet, provides particularly high mechanical strength, suitable for carrying heavy loads. For example, the embodiment of the pallet presented in the drawings, having dimensions as indicated with reference to Fig. 5A-5C, is able to carry heavy loads of up to 1500kg.
Preferably, the load support platform 101 is made by welding a top ribbed plate 110 comprising the substantially closed top surface 121 with a bottom ribbed plate 130 comprising the substantially closed bottom surface 141, from which the plurality of rows of feet 151-153; 154-156; 157-159 extend downwards. The plates 110, 130 are connected by welding at least part of the ribs of the top ribbed plate 110 with at least part of the ribs of the bottom ribbed plate 130. In particular, all ribs of the top plate 110 can be welded with all ribs of the bottom plate 130, as shown in the drawings. This allows easy construction of the pallet, by independently moulding the top plate 110 and the bottom plate 130 and forming the pallet by welding the two moulds.
As shown in the drawings, the internal ribbing may comprise a plurality of longitudinal ribs 111-113, 131-133 parallel to the rows of feet 151-153; 154-156; 157-159 and a plurality of transverse ribs 114-116, 134-136 perpendicular to the rows of feet 151-153; 154-156; 157-159. This assures stable mechanical properties of the pallet. Some longitudinal ribs may be situated coplanarly with the longitudinal vertical walls of the feet 151-159, as in the case of the rib 113. Other longitudinal ribs may be situated in between the planes defined by longitudinal vertical walls of the feet 151-159, as in the case of the ribs 111, 112. These longitudinal ribs 111, 112, located between each pair of neighbouring rows of feet 151-153; 154-156; 157-159 are particularly preferable to be steel-reinforced, in particular reinforced by steel rods 117, 118, in order to improve the mechanical strength of the pallet in the length direction in the area between the feet. Some transverse ribs may be situated coplanarly with the transverse vertical walls of the feet 151-159, as in the case of the rib 115. Other transverse ribs may be situated in between the planes defined by transverse vertical walls of the feet 151-159, as in the case of the rib 114 situated between the walls of one foot and in the case of the rib 116 situated between the walls of neighbouring feet. It should be noted that because the skid is easily detachable from the feet, the skid practically does not contribute to mechanical strengthening of the pallet, whereas its function is to activate the microswitches at automatic lines.
The construction of the pallet according to the invention is such that the mechanical strength necessary to support the loads for which the pallet is designed, is provided by the load support platform, without the need for additional strengthening, such as by joining the bottom surfaces 143 of the feet 151-159, as in the prior art pallets. Therefore, the bottom surfaces 143 of the feet 151-153; 154-156; 157-159 within at least one row, and preferably in all rows, are separate from each other, i.e. are not joined at all or are not permanently joined.
Some automatic warehouse and production systems have micro switch sensors which are configured to detect the presence of a pallet by detecting the presence of the pallet feet. Such sensors require the pallets to have elongate feet, i.e. feet extending along the whole length of the pallet. The pallet according to the invention may have the feet 151-153; 154-156; 157-159 within at least one row connected by skids 161-162; 163-164; 165-166, which are detachably connected at the bottom surfaces 143 of the feet 151-153; 154-156; 157-159. Due to the fact that the skids are connected in a detachable manner, the pallet is less prone to damage by pallet jacks than the pallets in which the elongate feet form a single element. In case a pallet jack hits the detachable skid 161-166, the skid may detach from one or both of the feet 151-159 to which it is connected, without breaking the feet. A detached skid 161-166 may be then easily re-attached to the pallet. Even if the skid is broken, it can be replaced by a new skid. Therefore, a pallet jack will usually damage only a skid, requiring replacement of only the skid, without the need to replace the whole pallet.
For example, the skids 161-166 may be connected to the feet 151-159 by snap-type fasteners 173-174; 144-145. In a particular embodiment, each skid 161-166 may comprise an elongate member 171 having a flat bottom surface 172 and protrusions 173, 174 extending upwards from the end portions of the elongate member 171, the protrusions 173, 174 configured to be snapped into openings 144, 145 in neighbouring feet 151-159 within a row such as to position the flat bottom surface 172 of the skid 161-166 coplanarly with the bottom surfaces 143 of the feet 151-159. The protrusions are most likely to be damaged during inappropriate operation of a pallet jack. However, since the protrusions form a part of the skid, then even if a protrusion is damaged, the skid can be replaced by a new skid in order to make the pallet fully functional again.
The elongate members 171 of the skids 161-166 may have a central flat top surface 175 and side edges 176, 177 raised above the central flat top surface 175. The raised side edges 176, 177 provide rigidness in the longitudinal direction of the skid. Each of the side edges 176, 177 is chamfered from both sides, such that the rolls of the pallet jack may easily pass over them.
In addition, the width of the skids 161-166 can be narrower than the width of the feet 151-159 to which the skids 161-166 are connected, which facilitates the detachment of the skids without damage.
In order to facilitate handling of the pallet by fork arms of pallet jacks or fork lifts, the vertical edges 146 of the feet 151-159 and/or the edges 142 of the substantially closed bottom surface 141 can be chamfered. This facilitates insertion of fork jacks into the openings of the pallet.
Optionally, the substantially closed top surface 121 may have openings 122 located above each foot 151-159. The openings 122 can be used for mounting various additional accessories for the pallet, such as rubber non-skidding inserts.
The plastic from which the pallet is made can be impact-resistant polyethylene, which can be obtained by recycling plastic packaging waste. This makes the pallet relatively cheap to produce and more environment-friendly.
In a particular embodiment, as shown in Figs. 5A-5C, the pallet can have three rows of three feet each, length L of 1200 mm and width W of 800 mm. The ribs may have a thickness of at least Tr 8 mm. The other horizontal and vertical walls of the pallet may also have a thickness of at least 8 mm. The total thickness Tp of the load support platform may be at least 50 mm. The four reinforcing steel rods may have a diameter Dr of at least 8 mm. A pallet of such configuration may carry a load of up to 1500kg.
The pallet shown in the drawings is an exemplary embodiment only. Other pallet configurations can be constructed according the invention, for example pallets having standardized sizes as specified in the ISO standard 6780 "Flat pallets for intercontinental materials handling - Principal dimensions and tolerances".
The terms "top", "bottom", "downwards", "upwards" as used throughout this specification refer to the pallet in its typical working position, wherein the pallet is situated horizontally, the bottom surface 143 of the feet standing on a support surface, such as a floor, and the substantially closed top surface 121 of the load support platform carrying a load thereon.

Claims

A pallet made substantially of plastic, comprising a load support platform (101) from which a plurality of parallel rows of feet (151-153; 154-156; 157-159) protrude downwards, wherein the load support platform (101) comprises a substantially closed top surface (121) and a substantially closed bottom surface (141) joined by internal ribbing, whereby the internal ribbing comprises a plurality of steel-reinforced plastic ribs (111, 112, 131, 132), the steel-reinforced plastic ribs (111, 112, 131, 132), extending along the direction of the rows of feet (151-153; 154-156; 157-159) characterized in that steel rods are placed inside the steel-reinforced plastic ribs.
The pallet according to claim 1, wherein the load support platform (101) is made of a top ribbed plate (110) comprising the substantially closed top surface (121) and a bottom ribbed plate (130) comprising the substantially closed bottom surface (141) from which the plurality of rows of feet (151-153; 154-156; 157-159) extend downwards, wherein at least part of the ribs of the top ribbed plate (110) are welded with at least part of the ribs of the bottom ribbed plate (130) to form the load support platform (101).
The pallet according to claim 1 or 2, wherein the internal ribbing comprises a plurality of longitudinal ribs (111-113, 131-133) parallel to the rows of feet (151-153; 154-156; 157-159) and a plurality of transverse ribs (114-116, 134-136) perpendicular to the rows of feet (151-153; 154-156; 157-159).
The pallet according to claim 3, wherein the top ribbed plate (110) and/or the bottom ribbed plate (130) have a longitudinal rib (111, 112, 131, 132) reinforced by a steel rod (117, 118, 137, 138) located between each pair of neighbouring rows of feet (151-153; 154-156; 157-159).
The pallet according to any of the preceding claims, wherein the bottom surfaces (143) of the feet (151-153; 154-156; 157-159) within at least one row are separate from each other.
The pallet according to any of the preceding claims, wherein the feet (151-153; 154-156; 157-159) within at least one row are connected by skids (161-162; 163-164; 165-166), which are detachably connected at the bottom surfaces (143) of the feet (151-153; 154-156; 157-159).
The pallet according to claim 6, wherein the skids (161-166) are connected to the feet (151-159) by snap-type fasteners (173-174; 144-145).
The pallet according to claim 6, wherein each skid (161-166) comprises an elongate member (171) having a flat bottom surface (172) and protrusions (173, 174) extending upwards from the end portions of the elongate member (171), the protrusions (173, 174) configured to be snapped into openings (144, 145) in neighbouring feet (151-159) such as to position the flat bottom surface (172) of the skid (161-166) coplanarly with the bottom surfaces (143) of the feet (151-159).
The pallet according to claim 8, wherein the elongate members (171) have a central flat top surface (175) and side edges (176, 177) raised above the central flat top surface (175).
The pallet according to claim 6, wherein the width of the skids (161-166) is narrower than the width of the feet (151-159) to which the skids (161-166) are connected.
The pallet according to any of the preceding claims, wherein the vertical edges (146) of the feet (151-159) are chamfered.
The pallet according to any of the preceding claims, wherein the substantially closed bottom surface (141) has chamfered edges (142).
The pallet according to any of the preceding claims, wherein the substantially closed top surface (121) has openings (122) located above each foot (151-159).
The pallet according to any of the preceding claims, wherein the plastic is impact resistant polyethylene.
The pallet according to any of the preceding claims, wherein the load support platform (101) has a thickness of at least 50 mm and the internal ribbing has a thickness of at least 8 mm.