Patent Application
20070151488
The present invention relates to a pallet foot for a pallet.
Such a pallet foot is known from U.S. Pat. No. 3,602,158 and comprises cut-to-size board, which is provided with indentations. In U.S. Pat. No. 5,365,857 mainly corrugated board or multilayer paper is used, the pallet being folded from a single layer of such material.
The prior art discloses numerous ideas for replacing standard wooden pallets by cardboard material pallets. Cardboard material pallets have the advantage that they can be supplied by the recipient of the product to a paper recycling circuit. However, such pallets are also increasingly used for weight reasons, because they are lighter than wooden pallets and give rise to lower transportation costs.
DE 201 03 902 U1 discloses a cardboard or corrugated board pallet having feet, which comprise several parallel and spaced runners or skids constructed in one piece with the upper section. In the folded arrangement the runners have a triangular or quadrangular cross section.
DE 195 23 492 A1 discloses a pallet using roll cores of paper, carpet and similar material rolls as support elements, the roll cores being arranged in two layer, superimposed and vertical manner.
Finally, WO 95/25672 discloses a pallet system comprising a flat upper section provided with tubular runners. The runners are folded from a flat cardboard. For stiffening the runners separate parallel-epipedic stiffening elements are introduced into the runners and e.g. comprise wound or honeycomb-like cardboard material.
The prior art cardboard pallets suffer from various disadvantages with respect to their low strength or stability, complicated manufacture, material consumption and large transportation volume for dispatching the pallet. In addition, due to the capillary action of the cardboard material, the known cardboard pallets are susceptible to water and moisture.
There is therefore a need for a pallet which is easier to manufacture, has a greater stability, uses less or more cost effective material, which is better protected against moisture and water and which is easier to transport. There is also a need for a method for the manufacture of such a pallet, as well as for a plant for the manufacture of such pallets.
More specifically the aforementioned problems are solved by a pallet foot for a pallet, which is characterized in that the cardboard tube comprises wound (recycled) paper layers.
As a result of the winding of the paper layers a particularly high strength is obtained, even when using recycled paper. The use of recycled paper reduces material costs.
Such a pallet foot can also be rapidly and easily produced from an angular cardboard tube. As the starting material is a tube, which only has to be worked or processed, no additional cardboard elements have to be made and installed. The reinforcements of the load-bearing areas are provided solely by the cardboard material present in the cardboard tube. This permits an absolutely waste-free pallet foot production. The tubular starting material is also particularly stable, because it has no adhesion points, pronounced seams, etc. and is instead preferably wound in one piece. Moreover, the stiffening of the load-bearing areas by the stiffening walls creates a stable and also very lightweight structure able to withstand high loads.
In addition, the machines in cardboard and paper factories have fixed working widths, so that constantly secondary webs are produced during the production of specific paper or cardboard widths. In the case of weight changes, there are also transition webs, which are also produced as waste. These secondary or transition webs are normally returned to the waste paper circuit or cycle. This leads to high costs for the paper factory, because the secondary and transition web rolls are too compact for direct recycling and are consequently unwound or sawn at high cost.
As only narrow paper or cardboard strips with a width of approximately 7 to 140 mm are required for winding the inventive cardboard tubes, the secondary and transition webs which occur as waste during paper production can be used without any difficulty and consequently have a worthwhile utilization. Wider secondary or transition webs merely have to be cut to the requisite strip width, which is readily possible in the paper factory. As secondary webs are otherwise virtually unsaleable, they can be obtained at a very favorable price and possibly even free, which greatly reduces the material costs for the pallet feet. The cardboard tube preferably has a quadrangular or octagonal cross-sectional shape. As a result of such shapes the pallet foot forms a planar bearing surface for a top plate of the pallet and a planar surface on the ground, so that the loads which arise can be distributed in large area manner.
In another preferred embodiment the cardboard tube is made from a cardboard material hardened by means of water glass. The hardening of the cardboard tube with water glass means that the pallet foot produced therefrom has a particularly high strength. In addition, water glass as a hardening and adhesive material is particularly inexpensive, because it only costs about ⅓ of the price of conventionally used adhesives. In addition, during hardening in the air water glass does not release toxic vapors. Moreover, following the hardening operation the cardboard tube is protected against water and moisture, so that the pallet can also be used in the open air.
Preferably the closed areas of the pallet feet have side walls provided with impressions running substantially parallel to the load or loading direction. The impressions or corrugations, compared with a planar surface, reinforce the side walls of the load-bearing areas and increase buckling resistance. The impressions can also pass into one another, which leads to a wave shape.
Preferably the closed areas are in each case subdivided into three or four chambers. Preferably the individual chambers of the closed areas have the same shape. The shape and number of chambers essentially determines the stability of the pallet. In addition to compressive forces resulting from the weight of the load, the preferably closed chambers can particularly well absorb transverse forces, which frequently arise during transporting and loading of the pallet.
In another preferred embodiment the stiffening walls are folded at folding grooves running parallel to the load direction. The folding grooves facilitate a precise folding of the stiffening walls. As the folding grooves run in the load direction, within the load-bearing areas the stiffening walls are vertical and therefore transfer the compressive forces which occur in the main load direction into the ground or base area.
Preferably the stiffening walls of a closed area are bonded flat to one another. A bonding of the stiffening walls increases the load of the load-bearing areas to a significant extent, because adhesion points can transfer shear forces between the stiffening walls.
The cardboard tube preferably has a continuous upper wall and a continuous lower wall, the inwardly folded side walls being bonded to the upper wall and the lower wall. The continuous upper and lower walls of the pallet foot serve as spacers and reinforcements for the load-bearing areas.
It is also preferable for the closed areas to in each case have at least one lateral window in order to link the pallet foot with a crossbar.
Specifically the aforementioned problems are also solved by a pallet having a substantially flat, planar cover plate and at least two pallet feet according to the invention. By adding a suitable cover plate, e.g. of wood, plastic, metal or cardboard, with the pallet feet a complete pallet is obtained which is adaptable to the particular intended use.
The top plate is preferably also made from cardboard or recycled cardboard, so that a completely recyclable cardboard pallet is obtained.
In another preferred embodiment the pallet feet are adhered parallel to one another to the cover plate.
The pallet preferably has at least one crossbar which is connected to the pallet feet and runs perpendicular to the latter. As a result of such a crossbar, the pallet stability is greatly increased, so that the cover plate material thickness can be reduced. For the same load it is e.g. possible to reduce the thickness of the comparatively expensive cover plate by approximately 50%, which leads to a cost reduction of up to 20%.
In addition, the crossbars can be used or omitted as a function of needs, which provides an individually configurable pallet system.
Preferably the crossbars are made from the same cardboard tube as the pallet feet, so that the same tube winding machine can be used.
The aforementioned problems are also solved by a method for the manufacture of a pallet foot for a pallet, which has the following steps, but which does not form the object of the present patent.
Punching lines of cut in the circumferential surface of a cardboard tube in order to cut out stiffening walls.
Stamping folding grooves into the circumferential surface of the cardboard tube for forming folding grooves for folding the stiffening walls.
Folding the stiffening walls in order to subdivide into chambers the load-bearing areas of the pallet foot.
As a result of the method according to the invention the advantages described in conjunction with the pallet feet according to the invention are obtained.
In a preferred embodiment the method has the following steps preceding the other steps:
Thus, starting with a paper starting material, the method produces a pallet foot with a specific length, specific strength and carrying load. The winding step can be varied in such a way that different cardboard tube wall thicknesses are obtained, so that the pallet foot has a different carrying load.
The method preferably also has the step of forming impressions in the circumferential surface of the cardboard tube, said impressions running substantially parallel to the desired load direction. The impressions or corrugations reinforce the circumferential surface of the cardboard tube.
Preferably the steps of punching lines of cut, stamping folding grooves and forming impressions are performed simultaneously, which reduces the pallet foot manufacturing time.
In another preferred embodiment the method also has the step of impregnating the cardboard tube with water glass. Preferably the paper strip from which the cardboard tube is wound is drawn through a gluing unit and one side of the paper strip is coated over its entire surface with water glass. The use of water glass as the adhering and hardening material is made possible in that immediately after the winding process the “compressing stamping punching process” is performed. As a result of tube compression an absolute bond is obtained, which in the case of conventional winding can only be brought about by cost intensive after treatment using high grade adhesives. In particular, the cardboard tube winding can take place at a much higher winding speed than in conventional methods, because any air voids or bubbles between the paper webs to be bonded can be expelled through the compression of the tube.
In a further preferred embodiment the method has the step of compressing and heating the cardboard tube so as to harden the latter in void free manner. Preferably the compressing and heating step is performed simultaneously with the punching stamping step. During compression the cardboard fibers are retained and the cardboard surface is smoothed, so that the pallet foot has reduced moisture absorption. As a result of heating the pallet foot drying time is reduced to such an extent that immediate further processing can take place. In the case of conventional drying, it would otherwise be necessary to respect drying times of up to two weeks.
The method preferably also has the step of applying adhesives to partial areas of the stiffening walls, so as to bond the latter together. Manufacturing pallet feet having a tube processing machine for punching lines of cut and introducing folding grooves into a circumferential surface of an angular cardboard tube and a folding machine for folding stiffening walls along the folding lines for the purpose of forming the load bearing areas of a pallet foot.
As a result of such a plant it is possible to rapidly and inexpensively produce pallet feet from cardboard tubes. The plant can operate completely automatically, so that it is possible to produce a large number of pallet feet with low piece costs.
The plant preferably also has a tube winding machine for producing a continuous cardboard tube and a cutting device for cutting the continuous cardboard tube, so as to give a cardboard tube with a desired length.
In another preferred embodiment the tube processing machine has an inner tool, which can be inserted into the cardboard tube and where said inner tool can be radially expanded to engage on the inner wall of the cardboard tube.
The inner tool preferably has replaceable working surfaces for grooving, stamping and punching or cutting. The working surfaces of the inner tool can consequently be easily replaced in the case of wear.
Preferably the inner tool also has at least one electrical heating element. Through said heating element the inner tool can be heated in order to aid hardening of the water glass impregnated and therefore moist cardboard tube. Therefore the cardboard tube is virtually “baked” or pressed into shape.
In another preferred embodiment the processing machine has outer tools, which comprise replaceable punching tools for punching lines of cut in the circumferential surface of the cardboard tube and replaceable stamping tools for making folding grooves in the circumferential surface of the cardboard tube. As a result of the cooperation between the outer and inner tools, the cardboard tube is compressed to such an extent that air is forced out between the cardboard tube paper layers and an optimum paper web bonding takes place.
The outer tool preferably has replaceable stamping tools for making impressions.
Preferably the plant also has edge cutters for punching longitudinally directed lines of cut in the circumferential surface of the cardboard tube.
The folding machine preferably has vacuum exhausters in order to bend the stiffening walls outwards from the circumferential surface of the cardboard tube. The vacuum exhausters are merely placed on the cutout side wall areas of the cardboard tube and vacuum is applied for the purpose of gripping the stiffening walls and bending them outwards.
The folding machine preferably has motor-driven turning claws, in order to fold the stiffening walls into the load-bearing cardboard tube areas. Following the bending up of the stiffening walls by means of the vacuum exhausters use can be made of turning claws in order to fold the stiffening walls to their desired shape.
Preferably the turning claws are turned by stepping motors and moved pneumatically up and down.
The problem of space-intensive transportation of the finished pallet is solved by a method for the manufacture of a pallet, said method having the following steps in the indicated order:
As the final method step is only performed by the end user, the comparatively bulky pallet is only obtained at this time. During dispatch to the end user the blanks only take up a limited space, so that shipping costs are low. A lorry or truck can usually load 800 empty Europa-size pallets. On dispatching the blanks approximately 8,000 individual systems can be transported in each lorry and they are then installed on the premises of the end user.
Preferably the blanks are pallet feet or crossbars and it is then left to the end user to decide which top or cover plate he wishes to use, e.g. of wood, plastic or cardboard. Moreover, as a function of the load to be transported, he has flexibility concerning the number of blanks required. For example, instead of three, in the case of light loads he may only use two feet per pallet, which would mean a material saving of approximately 30% per pallet. As a function of the load, the end user can also decide whether or not crossbars are to be used.
In another preferred embodiment the method also has the step of delivering the cover plate to the end user. Therefore the end user receives a complete construction set for a pallet. Approximately 3.5 kg, compared with a wooden Europa pallet weighing approximately 11 kg. Therefore these pallets can also be handled by female workers. In addition, a gas treatment such as is prescribed for export uses is rendered unnecessary, which further reduces manufacturing costs.
Preferred embodiments of the present invention are described hereinafter relative to the attached drawings, wherein show:
Preferred embodiments of the present invention are described hereinafter with reference to the drawings.
As a function of the intended use of the pallet 1 and the maximum planned loading, it is also possible to use only two pallet feet or more than three pallet feet.
Angular cross-section.
Pallet foot 10 of
Pallet foot 10 has a continuous upper wall 16, with which the pallet foot 10 is bonded to the cover plate 50, as well as a continuous lower wall 14 interconnecting and spacing the load-bearing areas 30 in order to improve the stability of the pallet foot 10.
Each pallet foot 10 comprises a cardboard tube 11 with an angular cross-section, which can be a specially wound cardboard tube or a cardboard tube obtained as waste product during paper or cardboard manufacture. Preferably, for winding the cardboard tube, use is made of recycled or waste paper from secondary or transition webs, which can be preferably impregnated or coated with water glass prior to winding in order to give an increased strength to the subsequent pallet foot 10.
Water glass is obtainable as potassium water glass (potassium silicate K2SiO3) or as soda water glass (sodium silicate Na2SiO3) and in the form of a syrupy solution of sodium or potassium silicate in water. Water glass hardens completely in air and serves as an inorganic binder giving the cardboard tube 11 and pallet foot 10 increased strength and moisture resistance. Water glass is used as a component for bonding, hardening and moisture protecting the pallet feet. Moisture protection can be further increased if the pallet feet are immersed 20 to 30 mm from their underside or completely in water glass As a result of the punching precision, no water glass can penetrate the interior of the load-bearing areas 30.
The lower view of
For stiffening the load-bearing areas 30 of each pallet foot 10 and for increasing the bearing capacity thereof, partial areas of the side walls of cardboard tube 11 are folded as stiffening walls 32 into the load-bearing areas 30. Thus, in the vicinity of the load-bearing areas 30 within the tube in each case a plurality of chambers 34 is obtained.
Preferred examples for the shape of such chambers 34 and preferred folding patterns are shown in
The gap between the stiffening walls 32 shown in
The same applies regarding the embodiment of
Obviously other folding patterns are conceivable for folding the punched out side walls 32 of cardboard tube 11 into the load-bearing areas 30 in order to form a plurality of chambers 34.
An outer tool 114 comprises cutting tools 115 for cutting lines of cut 38 into the circumferential surface of cardboard tube 11, punching tool 116 for making folding grooves 36 in the circumferential surface of cardboard tube 111 and stamping tools 117 for making impressions 39 for stiffening the circumferential surface of cardboard tube 11. The stamping tools 117 are preferably rounded at their working surface, so that there is a slight corrugation of the lateral face of cardboard tube 11, but no sharp edges are introduced which could aid buckling.
During the stamping process the continuous upper 16 and lower 14 walls also are given a not shown stamping, which increases the stability of both walls, particularly against sagging. As a result of the stamping operation the stiffening walls 32 are fixed internally and may not have to be bonded together. In addition, there is a reduction in the bearing surface of pallet foot 10 with respect to the cover plate 50, which makes it possible to improve bonding due to a higher contact pressure and the use of adhesive can be reduced.
As a result of such a stamping, there is a reduction to the bearing surface on the ground, so that moisture absorption is further reduced. In addition, damage to the pallet as a result of lift truck introduction is avoided, because the lift truck wheels are passed into the free spaces provided as a result of the curvature of the cardboard wall. Such a construction also permits the use of the pallet on automatic transport lines, as well as insertion and removal with respect to automatic storage areas.
The folding in device 127 comprises two turning claws 122, 123, shown in detail in
The folding in device 127 also comprises two stepping motors 124, 125, which in SPC-controlled manner turn the turning claws 122, 123. The left hand stepping motor 124 turns the entire folding in device 127 and the right hand stepping motor 125 turns a turning or rotating disk 126, which has a turning claw 123 and the associated pneumatics for moving up and down.
With the aid of such folding in devices 127 and vacuum exhausters 121 the folding in process for all the stiffening walls 32 of pallet foot 10 takes place automatically and simultaneously. The folding in process is illustrated in exemplified manner in steps 2 to 9 in
The top view of
Prior to the folding process, adhesive is applied to the areas of stiffening walls 32 to be bonded.
In working step 1 the vacuum exhausters 121 are placed on the punched side walls 32 of cardboard tube 11 and vacuum is applied to apply a suction to side walls 32. In working step 2 the vacuum exhausters 121 are pivoted outwards and the stiffening walls 32 are folded outwards, i.e. away from cardboard tube 11. In working step 3 the turning claws 122, 123 are placed on the edges of stiffening walls 32 in that the turning claws 122, 123 are moved pneumatically downwards. In
In working step 4 the outer turning claws 122 are turned in, so that the initial folding takes place at a first folding groove 26. In working step 5 the outer turning claws are removed, i.e. moved upwards and the central turn-in claws are turned-in in order to carry out a second folding if this is desired.
In working step 6 all the turning claws are removed by pneumatically raising them. In working step 7 the stiffening walls 32 are folded automatically into the load-bearing areas 30 by pressure from the outside by means of the folding device and as symbolized by the arrows.
Finally, in working step 8 the remaining end members 37 are folded downwards and upwards and bonded to the stiffening walls 32.
The continuous cardboard tube 12 is delivered by the tube winding machine 150 and cut by a cutting device 160 into cardboard tubes 11 having a desired length. Preferably the cardboard tube 11 has a length of 1.40 meters.
After cutting off, the cardboard tube 11 drops onto a first conveyor belt 170, from where it is conveyed onto a second conveyor belt 180, in the manner symbolized by the arrows. The second conveyor belt conveys the cardboard tube 11 to the given processing lines. In
Level with the first processing line, by means of an ejector 185 cardboard tube 11 is conveyed from the second conveyor belt 180 to a tube depot 200. If there is an overcapacity of tubes, then the cardboard tubes 11 are collected at the end of conveyor belt 180 in a not shown magazine. If required, the cardboard tubes 11 can be supplied to the second conveyor belt 180 again via a further tube depot 190.
From tube depot 200, the cardboard tubes 11 are gripped by means of a first transport cross 210 by a vacuum exhauster and conveyed to the tube processing machine 110. For this purpose the transport cross 210 moves upwards and rotates by 180°. The vacuum is then removed and the cardboard tube 11 drops into the tube processing machine 110. The transport cross 210 then returns to its starting position.
The working process in connection with cardboard tube 11 commences in tube processing machine 110. The six pressure cylinders 130 to the right and left move to “fixing”, cardboard tube 11 only being gently held and is not compressed. By means of toothed gear transporters 145 the inner tools 111 are speedily introduced into the cardboard tube 11. Simultaneously the upper pressure cylinder 135 (cf.
Following the hardening of cardboard tube 11, or even after a partial hardening, pressure cylinders 130, 135, 140 and toothed gear transporters 145, 146 are moved back into their starting position.
The completely cut cardboard tube 11 provided with folding grooves 36 and impressions 39 is then conveyed by a second transport cross 220 from tube processing machine 110 to folding machine 120, where the aforementioned, requisite folding processes are performed.
The pallet feet 10 are now finished and are conveyed by a third conveyor belt, which links all the existing processing lines to a not shown depot.
The pallet feet 10 can then be bonded with a suitable cover plate 50 to give a pallet 1. Preferably, however, this final assembly step does not take place directly following the manufacture of the pallet feet 10, but instead only on the premises of the end user. For this purpose the finished pallet feet 10 are sent to the end user separate from the cover plates 50. The end user can then carry out the final assembly (bonding, joining together, tacking, etc.). This reduces the transport volume to a minimum and the transportation costs for dispatching the pallets are minimized.
It is obviously also possible to carry out the final assembly of the pallets by the manufacturer of pallet feet 10, in the case where the end user does not wish to carry out the assembly process.
Like the pallet feet 10, the crossbars 300 comprise a wound cardboard tube 11. The necessary cardboard tube can be produced on the same tube winding machine 150 as the tubes 11 for pallet feet 10. By punching, grooving and stamping, in each case two crossbars 300 can be made from one cardboard tube 11 of the requisite length.
As is shown in a cross sectional view in
For joining the pallet feet 10 to the crossbars 300, in their load-bearing areas 30 the feet 10 are equipped with side windows 22, which are also punched in the manner shown in
The crossbars 300 are produced in the same way as the pallet feet 10 using a corresponding plant. The crossbars 300 are also compressed, punched, grooved and given impressions in a single operation by means of the tube processing machine 110, provided that this is desired. Subsequently and using a folding machine 120, the folds are made in side walls and pegs 310.
| Number | Date | Country | Kind |
|---|---|---|---|
| 04009201.7 | Apr 2004 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP05/02350 | 3/5/2005 | WO | 7/10/2006 |
