EP1048578A1

EP1048578A1 - Pallet

Info

Publication number: EP1048578A1
Application number: EP97946148A
Authority: EP
Inventors: Shigeru Arai
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-12-08
Filing date: 1997-12-08
Publication date: 2000-11-02
Also published as: AU5138598A; WO1999029579A1

Abstract

The pallet of the present invention is made of a sheet of corrugated cardboard as its material. A W-structure material comprising fork insertion openings and folding lines is folded into a W-structure. Auxiliary members are inserted into the respective openings of that W-structure. After ridge cross sections of the W-structure are coated with adhesive, the W-structure is inserted between a top board and a bottom board to be fixed between them. Further, side wall flaps connected to the top board and bottom board are bent and corresponding side wall flaps of the top board and bottom board are fixed with adhesive, to form the pallet of the present invention. The pallet having the W-structure of the present invention has superior characteristics in its pressure capacity of course, and with respect to flexural strength, shear strength, and unbalanced load, in which many pallets of corrugated cardboard have weak points. Further, strengths and size can be optionally decided. Owing to its lightweight and simple structure, the production cost of the pallet of the present invention is cheap.

Description

Technical Field

The present invention relates to a cargo pallet made of stiff sheets of thin board represented by a sheet of corrugated cardboard, and has openings for insertion of a fork.

Background Art

Recently, instead of a wooden pallet, has been used a pallet whose material is mainly corrugated cardboard.. The wooden pallet is always worried about troubles caused by harmful insects, excessive water content, wood resin, and the like inside the wood. A pallet made of paper is not only free from such worries, but also a homogeneous product manufactured in a factory, being light in weight and low in price. Accordingly, a paper pallet grows rapidly as a pallet for export, etc. However, the pallet made of corrugated cardboard is defective in that it is weak as a pallet since its material is a sheet of corrugated cardboard. Although a pallet having leg members made of paper tubes or laminated sheets of corrugated cardboard is strong in pressure capacity for a static plane load, it lacks an aptitude as a pallet for products of unbalanced load or of little rigidity, thus being limited in its fields of use. Accordingly, a pallet of corrugated cardboard improved such that rigidity of is product-mounting surfaces (hereinafter, referred to as "top board") is increased and it is usable for a wider range of fields has been proposed.
Japanese Unexamined Patent Laid-Open No. 4-215943 discloses a pallet increased in rigidity of its top board by folding a sheet of corrugated cardboard into a trapezoid shape to obtain a slender beam and engaging such slender beams into a grid. However, many folded beams are necessary for obtaining sufficient rigidity, and further, a strongly-built large apparatus is required for engaging beams into a grid. Thus, this technique is defective in that production cost becomes larger. Further, since many beams are engaged into a grid, it is impossible to efficiently manufacture pallets of various sizes, the weight of a pallet becomes larger and its cost becomes higher.
Japanese Unexamined Patent Laid-Open No. 8-175544 discloses a pallet using leg members of continuous triangles that are made by folding a sheet of corrugated cardboard. The pallet of this form is strong in its static pressure capacity. However, similarly to other pallets made of corrugated cardboard, its top board is only a sheet of corrugated cardboard placed in a plane Accordingly, it does not go so far as to improve the flexural rigidity of its top board.
Japanese Unexamined Patent Laid-Open No. 8-72876 discloses a pallet in which a so-called angle corner formed into an L-shape by laminating cardboard several times is used as a reinforcing member. This pallet is improved in its flexural strength of the top board. However, the angle corner is an expensive member. Further, since many sheets of joined paper are used, it is heavy and inferior in processability. Further, many angle members are required for reinforcing the top board, and the angle corners should be joined one by one to the top board. Thus, it has an important defect in that the produced pallet becomes very expensive.
Accordingly, an object of the present invention is to provide a pallet made of a sheet of corrugated cardboard improved with respect to the defects of the conventional pallets made of corrugated cardboard. Namely, the object is to provide a corrugated-cardboard pallet that is (1) of course, strong in its pressure capacity, (2) strong in its flexural strength and shear strength, (3) made of a few members, (4) lightweight, (5) easily producible, and (6) inexpensive.

Disclosure of the Invention

The present invention has made the best use of the characteristic of a sheet of corrugated cardboard, i.e., rigidity, to complete a pallet largely improved in the flexural and shear strengths of its top board.
When a sheet of corrugated cardboard is used in a flat state, it is not so strong in both flexural strength and pressure capacity. In particular, when a sheet of corrugated cardboard is bent in parallel with the corrugation lines, it easily bends. Accordingly, the conventional methods in which a sheet of corrugated cardboard is used in a flat state as material for a top board, it is impossible to largely improve flexural strength. However, in an upright state, a sheet of corrugated cardboard becomes remarkably strong in both flexural strength and pressure capacity. The present invention utilizes this property of a sheet of corrugated cardboard, to solve the conventional problems.
A pallet according to a first invention of the present invention is constructed as shown as the pallet 1 in Fig. 1, such that one or plurality of W-structures 120 are coated with adhesive in it's ridge portions, and those W-structures are inserted and pressed between a top board 110 and a bottom plate 130, to be fixed between them.
A characteristic of the present invention lies in the mentioned W-structure 120. On the other hand, another characteristic lies in the shape of the side plates 1205, 1206 constituting the W-structure 120. Another characteristic lies in the structure of the W-structure 120 constituted by the side plates. The development of the W-structure 120 is shown in Fig. 3. Fig. 3 shows, at the same time, a front view of a W-structure material 1201. As shown in Fig. 3, a folding line is between adjacent side plates 1205, 1206, which are connected in reversed relation to each other, so that a sheet of corrugated cardboard makes thus a series of connected side plates. By folding the side plates 1205, 1206 of the mentioned W-structure material 1201 in trough lines 1202 and ridge lines alternately, the W-structure 120 is formed to have truss structure whose cross section shows a series of V-shapes.
The side plates 1205, 1206 as another characteristic of the present invention (hereinafter, represented by 1205 for the sake of simplicity) comprises two top board reinforcing members, three leg members, and two cutouts cut out for insertion of a fork. Fig. 4 shows a shape of the side plate 1205 as a rectangular plate having two cutouts (cut out to have a height h1 and a width w1, and hereinafter referred to as openings 120a). The mentioned top board reinforcing member is a portion enclosed by the width w1 of the cutout and a height h2 obtained by subtracting the height h1 of the cutout from the width L of the side plate 1205. The mentioned leg members are portions enclosed by the width L of the side plate 1205 and each width w2 of leg portions at both ends and a width w3 of a leg portion in the center, except for the mentioned openings. The vertical height H of the W-structure 120 from the ground varies depending on an angle at which the side plates 1205 form the V-shapes. From the practical viewpoint, however, H is not largely different from the width L of the side plate, and hereinafter, the width L of the side plate is also expressed by the height H of the W-structure from the ground.
The W-structure material 1201, which comprises the mentioned side plates 1205 and the mentioned folding lines, can be easily manufactured by stamping a sheet of corrugated cardboard by means of a die cutter.
The pallet of this invention has simple structure. Its pressure capacity and flexural strength can be optionally controlled. It is a pallet made of corrugated cardboard, which is lightweight and whose production can be easily automated.
A second invention provides a pallet structure in which the folding lines of the W-structure comprise ridge folding lines 1202, each of which is a half-cuffing line in which folding is carried out upwardly to form a shape such as "Λ", and trough folding lines 1203, each of which comprises, in turn, full-cutting lines and a guideline 1204 and is bent downward to form a shape such as "V". By stamping the folding lines by using a die made in accordance with the above-described structure, the W-structure material can be easily folded into the W-structure 120 manually or using a machine.
A third invention provides a pallet structure in which auxiliary members 340 are respectively inserted into the openings 120a for insertion of a fork, to protect the cross sections 120f of the openings.
According to this invention, a fork does not come in direct contact with the cross sections of the openings, so that the cross sections can be protected from the fork.
A fourth invention provides a pallet structure, in which the auxiliary member 340 is provided with a plurality of form retention wings 4304 cutout upward or right and left, in order to protect the openings 120a, and those form retention wings are inserted into corresponding openings 120a of the W-structure.
According to this invention, the truss structure of the W-structure is firmly fixed by means of the form retention wings. Thus, even when urgent braking is applied while the pallet is in transit by a truck, risk that the W-structure is destroyed becomes smaller, and thus a stable and strong pallet is obtained.
A sixth invention provides a pallet structure in which four peripheries of each of the top board 110 and the bottom board 130 are provided with side wail flaps 6102, 6103, or 6302, 6303, respectively. Those side wall flaps are bent and joined to form a body box 630 and a lid box 610. The W-structure 120 is contained in the body box 630 and then covered with the lid box 610, to obtain the pallet structure.
According to this invention, the body box and the lid box may have been formed separately. Then, the pallet can be easily formed by putting the W-structure inside the body box and then covering it with the lid box.
A seventh invention provides a pallet structure, in which side wall flaps 7102 and 7302 are connectedly provided in right and left of each of the top board and the bottom board. The W-structure 120 is coated with adhesive in its ridge lines and inserted between the top board and the bottom board. Then, the side wall flaps connected to the top board and the side wall flaps connected to the bottom board are coated with adhesive and bent. Then, corresponding side wall flaps are pressed to be connected with each other, to form the pallet structure.
According to this invention, the top board and the bottom board connectedly provided with side wall flaps can be manufactured by a corrugating machine. Thus, it is not necessary to prepare a die or to stamp cardboard in another process, thus reducing production and processing costs.
An eighth invention provides a pallet structure in which members 8210, 8211 (hereinafter, referred to as cutout remnants) that have been cut out and discarded to provide the openings 820a are retained being connected to the side plates 8205 of the W-structure 820 and bent toward the top board.
According to this invention, by bending the cutout remnants toward the top board, while they are connected to the side plates, not only the flexural strength but also pressure capacity can be strengthened. Further, when the cutout remnants 8210, 8211 are cut out to have such lengths that ends of both remnants contact with each other when they are bent to be parallel with the top and the bottom, ridge intervals of the W-structure 120 can be maintained constant, and the truss structure can be fixed.
A ninth invention provides a four-way insertion pallet structure 6 shown in Fig. 21 in which the above-mentioned leg members abutting the top board are partly cut out to form beam openings 920h, 920i. Then, three of four-way insertion W-structures 920 having the beam openings are arranged in parallel at suitable intervals. Then, beam members 990 are folded and inserted into respective beam openings. Then, that W-structures inserted with the beam members are put and fixed between the top board and the bottom board, to obtain the four-way insertion pallet structure.
This invention provides a four-way insertion pallet having large flexural strength, since the flexural strength in crosswise direction is reinforced by the top board reinforcing members of the W-structure 910 and the flexural strength in the front-to-rear direction is reinforced by the beam members 990.
A twelfth invention provides a pallet structure in which a stiff thin plate such as plastic corrugated cardboard, plastic sheet, joined paper, plywood, ceramic, metal, or the like is used as component material in each pallet of the first through ninth inventions.
The first through ninth inventions relate to construction and structure of a pallet, and the structural characteristics are not changed even when material used for making the pallet is changed, and characteristics common to the structure. In other words, when right material is used in right place in accordance with environments where the pallet is used, the structural characteristics of the present invention can be effectively utilized. Thus, it is possible to obtain a pallet that use small quantity of material and has simple structure.
As described above, the pallet using the W-structure according to the present invention is strong in its flexural strength, pressure capacity and shear strength. Further, by varying the number of the side plates, optional strengths can be obtained, and the pallet can be adapted for various sizes. Further, since the raw material used is small, a lightweight pallet can be obtained. Further, the production cost of the pallet is cheap owing to its simple structure.
In the present invention, when a sheet of corrugated cardboard is used, the direction of corrugation lines is not specified. The direction of the corrugation lines in use may be decided depending on characteristics required for the pallet or sizes of the pallet. Namely, in the case of a pallet for which pressure capacity is required, corrugation lines in the W-structure may be used in the vertical direction. In the case of a pallet for which flexural strength is important while pressure capacity is not required so much, the direction of corrugation lines may be used in parallel with the ridge lines, so that strong flexural strength is obtained. Further, in that case, the folding direction of the W-structure becomes the direction of the machine, and many side plates can be obtained from a sheet of corrugated cardboard, thus suppressing the production cost to a lower level.
Further, with respect to material of a sheet of the corrugation cardboard, kinds (quality, basis weight, and the like) of liners and corrugating medium may be selected in accordance with quality characteristics required for a pallet. Flute of a sheet of corrugated cardboard may be selected from various kinds (A, B, C, E, H, and the like) on the market. Further, depending on strength, corrugated cardboard of single wall, double wall, triple wall, or the like may be suitably selected. Further, water resistant material cardboard, laminated paper, polysand paper or the like may be used as material for a sheet of corrugated cardboard, to obtain a pallet of corrugated cardboard that is resistive to humidity and water.
Further, pallets of various strengths may be obtained by combining a sheet of corrugated cardboard with other various stiff materials.

Brief Description of Drawings

Fig. 1 is a perspective view of a pallet 1 according to the present invention;
Fig .2 is a side view of the pallet 1;
Fig 3 is a development of a W-structure of the pallet 1;
Fig. 4 is a side view of the W-structure of the pallet 1;
Fig. 5 is a perspective view of the W-structure material;
Fig. 6 is a perspective view of the W-structure;
Fig. 7 is a development of an auxiliary member having a rectangular opening;
Fig. 8 is a perspective view of the same;
Fig. 9 is a perspective view showing an auxiliary member whose retention wings projected upward are inserted into the openings;
Fig. 10 is a development of the auxiliary member having upwardly-projected retention wings at the opening;
Fig. 11 is a perspective view showing the auxiliary member whose retention wings projected right and left are inserted into the opening;
Fig. 12 is a perspective view of a pallet 2 having trapezoidal openings;
Fig. 13 is a development of the W-structure having the trapezoidal openings;
Fig. 14 is a perspective view showing a box type pallet 3;
Fig. 15 is a perspective view showing a lid box for the box type pallet 3;
Fig. 16 is a perspective view showing a body box for the box type pallet 3;
Fig. 17 is a perspective view showing a deformed box type pallet 4;
Fig. 18 is a side view showing a pallet 5 reinforced by cutout remnants cut out from the openings;
Fig. 19 is a development of a W-structure of the pallet 5;
Fig. 20 is a perspective view of the reinforced W-structure;
Fig. 21 is a perspective view showing a four-way insertion pallet 6 provided with cutouts for beams, with beams being inserted into the cutouts;
Fig. 22 is a development of a W-structure of the pallet 6;
Fig. 23 is a development of the beam members for the pallet 6;
Fig. 24 is a perspective view showing a pallet 7 provided with W-structures without having an opening, as leg members; and
Fig. 25 is an exploded view showing a pallet 8 in which a box and a pallet are integrated.

Best Mode for Carrying Out the Invention

Referring to the attached drawings, the present invention will be described in detail.
A pallet 1 according to a first invention of the present invention is shown in Figs. 1 and 2 as a perspective view and a side view, respectively. The pallet 1 is simply constructed such that joining its members, i.e., a top board 110, a W-structure 120 and a bottom board 130 in descending order, with an adhesive completes it.
The basic element of the present invention is the W-structure 120, whose development is shown in Fig. 3 as a W-structure material 1201. The W-structure material 1201 includes cutouts 1209 (openings 120a) enclosed by full- cutting lines 1207, 1208 for insertion of a fork, and upward folds 1202 and downward folds 1203 for folding it into the W-structure 120, these folds being formed next to each other alternately. Here, folding direction of each fold may be reversed, and, in that case, reference numerals of folds and cutting planes will be reversed in the following figures.
When the W-structure material 1201 is folded at the folds 1202, 1203, it becomes the W-structure 120. The W-structure 120 comprises side plates referred to by the reference numerals 1205 and 1206 (hereinafter, the same, numeral 1205 is used for the sake of simplicity).
The strength of the pallet 1 is generally proportional to the number of sheets of the side plates 1205, and accordingly, can be controlled at will by changing the number of the side plates 1205 of the W-structure 120. Further, the strength of the side plate 1205 depends on the kind of material of the sheet of corrugated cardboard, the kind of flute, and the like. Further, the strength of the side plate 1205 can be easily estimated from column crush strength of the side plate and overall ring crush of the material paper.
However, since the W-structure 120 has the openings 120a in the side plate 1205, the strength of the pallet 1 depends on the shape of the openings 120a. Namely, as shown in Fig. 4, which is a front view of the W-structure 120 and also a construction view of the side plate 1205, the flexural strength depends on the height H of the W-structure 120, the height hI of the openings, the width w1 of the openings, and the like.
The flexural strength of the pallet, which is the greatest characteristic of the present invention, becomes Larger as the height H of the W-structure 120 becomes larger, and becomes weaker as the height h1 of the openings becomes larger. In other words, when the height h2 of a top board reinforcing member, which is the difference between the height H of the side plate 1205 and the opening h1, becomes larger, the flexural strength becomes larger. Generally, the flexural strength is proportional to a square of the thickness, although it does not apply unconditionally since the pallet of corrugated cardboard is made of heterogeneous material including air spaces and the flexural strength is also affected by two openings provided in the center of the pallet. Thus, the pallet having the structure of the present invention has remarkably large flexural strength since the heights H and h2 of the W-structure are large.
Further, the flexural strength depends on the height h1 of the openings, the opening width w1 of the openings 120a, a distance w2 between an opening 120a and the other opening 120a, a distance w3 from the end of the pallet, and the like. Accordingly, experiments are required to know the detailed flexural strength.
To make a pallet having large pressure capacity, a sheet of corrugated card board is used with its corrugation lines being arranged in the vertical direction. This direction is the widthwise direction of a corrugating machine. An integer obtained by dividing the limited width of a sheet of corrugated cardboard by the height H of the side plate is the number of the side plates 1205 obtained from a sheet of corrugated cardboard. Thus, only a limited number of side plates 1205 are obtained in one sheet of W-structure material 1201, and accordingly, the strength of the pallet is also limited. However, when two or more sheets of W-structure material 1201 are used, almost an arbitrary number of side plates 1205 can be obtained, and accordingly, also arbitrary strength of the pallet can be obtained.
Further, an interval w4 between ridge line cutting planes 120b of the adjacent side plates 1205 of the W-structure 120 is short, and practical flexural strength of the top board becomes larger.
Further, the openings 120a of the W-structure can be optionally designed with respect to the width w1 of the openings 120a, the distance w2 between two openings 120a and the height h1 of the openings, considering the size of the fork and the method of carrying.
A second invention of the present invention relates to the folding lines of the W-structure material 1201 of a sheet of corrugated cardboard. Figs. 5 and 6 are perspective views of the W-structure material and the W-structure, respectively. The folding lines of the present invention includes the upward fold 1202 of a half-cutting line in which an upper liner 11 and corrugating medium 12 are cut except for a lower liner 13, and the downward fold 1203 comprising a guideline 1204 and a full-cutting line in which the material is cut from the upper liner 11 through the lower liner.
According to this invention, the upward fold 1202, in which the W-structure material 1201 is folded into a "Λ"-shape, is the half-cutting line 120c, and accordingly, it can be easily folded upward. Here, that half-cutting line may partly include a full-cuttingly.
Further, the downward fold 1203, in which the W-structure material 1201 is folded into a "V"-shape, comprises the full-cutting line 120b, and thus, the upper liner 11, the corrugating medium 12, and the lower liner 13 have been cut. Further, the downward fold 1203 comprises the guideline 1204 in a portion where the full-cutting line 120b does not exist. Accordingly, the downward fold 1203 can be easily folded downward. Although the guideline 1204 may be provided in any portion in the "V"-shape fold 1203, it is desirable that the guideline 1204 is provided in two portions on the right and the left and/or in one portion in the center of the guideline. Although the length of the guideline 1204 varies much or less, depending on the material of a sheet of corrugated cardboard and the like, it is desirable that the length of one portion is about 60 mm.
Further, the W-structure 120 can be folded such that the sides of the side plates 1205 become rectangular column shapes contact to each other. Thus, adhesive can be easily coated on upper and lower cut surfaces 120b, 120c of the W-structure. The cut surfaces 120b, 120c have honeycomb structure Thus, when the adhesive is coated on the cut surfaces 120b, 120c, the adhesive can enter into the insides of the cut surfaces 120b, 120c. Accordingly, as the effect of the adhesive, the material in the neighborhood of the cut surfaces 120b, 120c becomes strengthened, and the flexural strength, pressure capacity, and water resistance are improved.
Further, the cut surfaces 120b, 120c of the W-structure 120 are larger in their cut surface areas in comparison with a ridge line portion 120e bent in the guideline 1204. Thus, the adhesive can be easily coated on the cut surfaces 120b, 120c, and adhesion with the top board and the bottom board becomes satisfactory.
Further, the cut surfaces 120b, 120c have sleeve shapes, and accordingly, the pressure capacity can be increased in comparison with the ridge line portion 120e bent in the guide line 1204.
Further, in the W-structure material 1201, the upward folds 1202, the downward folds 1203, the guidelines 1204, and the cutouts of the openings 120a can be formed by one stamping, and the stamped sheet is obtained as a continuous sheet.
According to a third invention of the present invention, an auxiliary plate 340 of a sheet of corrugated cardboard is inserted into the opening 120a of the W-structure 120. Figs. 7 and 8 show a development and a perspective view of the auxiliary plate 340, respectively.
The present invention has structure that, when a fork is inserted into the openings 120a of the W-structure 120 of the pallet 1 and comes into contact with the cutout cross sections 1207, 1208 of the openings 120a, the cutout cross sections 1207, 1208 are readily torn. Accordingly, to protect the cutout cross sections 1207, 1208, the "Π"-shaped auxiliary member 340 that is adjusted to the shape and size of the opening 120a is inserted into the opening 120a, so that a fork is prevented from directly come into contact with the cutout cross sections 1207, 1208. When a fork obliquely hits a wall surface 3401 of the auxiliary member 340, the fork slides along the ceiling 3401 or a side wall surface 3402 to be inserted, thus remarkably reducing damage of the W-structure 120.
Further, according to this invention, the ceiling 3401 of the auxiliary member 340 supports cutout cross section 120f of the opening 120a, and the ridge interval w4 is correctly maintained, so that the flexural strength and the pressure capacity are improved.
According to a fourth invention of the present invention, form retention wings 4304 are provided to the auxiliary member 340 of the third invention. Figs. 9 and 10 show a perspective view and a development, in which the auxiliary member 430 having the mentioned form retention wings 4304 is inserted into the W-structure 120 of the pallet 1. Upwardly from the "n"-shaped auxiliary member 430, are provided two or more form retention wings 4304. Those form retention wings 4304 are inserted through cutout gaps of the opening 120a, so as to fix the opening cross section 120f. In other words, the prescribed W-structure can be maintained without being fixed to the top board 110 and the bottom board 130 with adhesive. As shown in the development of Fig. 10, the form retention wings 4304 is made such that a part of a ceiling member 4301 is cut in accordance with cutout lines 4305 being adjusted to the shape and the size of the W-structure 120, and then, the ceiling member 4301 is bent at guidelines 4303, so as to make the form retention wings 4304 of projective shapes.
Fig. 11 is a perspective view showing W-form retention wings 4304 extending right and left, and is inserted through the opening 120a of the W-structure 120. This structure has the same effect as the Fig. 9. In this case, the projective form retention wings are cut out from side walls 4302 of the auxiliary member 430.
A sixth invention of the present invention provides a pallet 3 formed such that a lid box 610 is made to comprise side wall flaps 6102, 6103 provided in connection with the top board 6101 and paste margins 6107, a body box 630 is made to comprise side wall flaps 6302, 6303 provided in connection with the bottom board 6301 and paste margins 6307, the W-structure 620 is contained in the body box 630, and the lid box 610 is covered on to the body box 630. Figs. 14, 15 and 16 are perspective views of the pallet 3, the lid box 610 and the body box 630. Here, the side wall flaps 6103 of the lid box 610 and the side wall flaps 6303 of the body box 630 have cutouts 6109, 6309 as insertion openings corresponding to the openings 620a of the W-structure 620.
According to the present invention, the pallet 3 can be easily manufactured by making the body box 630 and the lid box 610, and then, putting the W-structure 620 in the body box 630 and covering the lid box 610.
According to a seventh invention of the present invention, the above mentioned pallet 3 does not have the side wall flaps 6103 in front and rear of the lid box 610 and the side wall flaps 6303 in front and rear of the body box 630. The W-structure 720 is coated with adhesive in the ridge line cross sections and contained between a top board 7101 connectedly provided with side wall flaps 7102 and a bottom board 7301 connectedly provided with side wall flaps 7302, and thereafter, the side wall flaps 7102 and 7302 are bent and corresponding side wall flaps are adhered to each other, so as to obtain a pallet 4. Fig. 17 is a perspective view showing the pallet 4.
According to the present invention, the pallet is completed only by bending the side wall flaps 7102, 7302 connectedly provided to the top board 7101 and the bottom board 7301. Accordingly, this pallet is suitable for an automatic pallet manufacturing machine.
A pallet without the side flaps such as the pallet 1 is not so strong with respect to shear force in the direction of fork insertion, in comparison with sear force in the crosswise direction of the pallet. However, as in the pallets 3 and 4 of the sixth and seventh inventions, when the side wall flaps 6102, 7102 and 6302, 7302 provided in connection with the top board or the bottom board are joined to each other, it is possible to remarkably improve shear strength in the direction of fork insertion.
According to an eighth invention of the present invention, a waste member (referred to as a cutout remnant 8210 in the present invention) that is usually abandoned as a cutout from an opening 820a of a W-structure 820 is used as a top board reinforcing member. Fig. 18 is a side view showing a pallet 5 of an embodiment. Figs. 19 and 20 is a perspective view of a part of the W-structure 8201 and a perspective view of the W-structure 820.
As shown in the perspective view of the W-structure material in Fig. 19, a cutout remnant 8210, 8211 (hereinafter, represented by 8210 for the sake of simplicity) is obtained by cutting a center of a portion enclosed by half-cutting lines 8207 and full-cutting lines 8208, with a full cutting line 8213. This cutout remnant 8210, 8211 is bent toward the top board 8101, while kept in connection with the side plate 8205, 8207 (hereinafter, represented by 8205 for the sake of simplicity) corresponding to the W-structure 820 by means of the half-cutting line 8207.
Since the pallet 5 uses the cutout remnant 8210 of the opening 820a as described above, the flexural strength and the pressure capacity are improved by 20 % or more, in comparison with the strengths in the case of not using the cutout remnant 8210.
Thus, according to this invention, since the cutout remnants 8210, which have been cut out and discarded, are used, the W-structure material 8201 is used exhaustively, the strengths are improved, and trouble for discarding waste can be avoided.
In a ninth invention of the present invention, a set of two or three W-structures 920 are arranged in parallel, to obtain a four-way insertion pallet. Fig. 21 is a perspective view of a pallet 6 of an embodiment in which three W-structure 920 are arranged in parallel. Fig. 22 is a development 9201 of one W-structure 920.
In the above-mentioned W-structure 920, its leg members to be abutted to the top board are partly cut out to provide three lines of beam openings 920h, 920i, 920h (hereinafter, represented by 820h for the sake of simplicity). Three such W-structures 920 for four-way insertion are arranged in parallel to provide intervals into which a fork can be inserted, and then, after inserting three beam members 990 into the beam openings 920h, are connected to the top board 910 and the bottom board 930.
In the pallet 6 of the present invention, since a fork can be inserted into it from the side of the openings 920a or from the side of side openings 920y, thus a four-way insertion pallet is obtained.
Higher flexural strength can be obtained, owing to the W-shaped structure of the W-structure 920 for insertion from the direction of the openings 920a, and owing to the beam members 990 that are made of a sheet of corrugated cardboard folded into W-structure and have inserted into the beam openings 920h, for insertion from the side opening 920y. Here, the flexural strength of the beam member 990 depends on the number of side plates constituting the beam of the beam member 990, the height of folding, and the kind of corrugated cardboard sheet constituting the beam member. The beam member 990 includes an upward fold of a half-cutting line 9902 and a downward fold comprising a full-cutting line 9903 and a guideline 9904. Its development is shown in Fig. 23.
In the Figs. 1 ― 23, differences in sizes and numbers of the same pallet in its development, perspective view and front view have occurred owing to abbreviation and simplification to avoid complexity in the drawings. Of course, in practical working, drawings and numerical values are designed and made, taking mutual relations into consideration.

Industrial Applicability

As described above, the present invention can provide the pallet made of a sheet of corrugated cardboard that is remarkably improved in flexural strength of its top board owing to openings provided in the W-structure, and is adapted for a product having unbalanced load or liquidity owing to the strengthened pallet mounting surface. The production of that pallet can be easily automated for mass production.

Claims

(amended) A pallet comprising a W-structure material made of a sheet of corrugated cardboard in which a plurality of side plates are connectedly provided being reversed to each other via folding lines ; wherein:

in each of said side plate in a rectangular shape of width L and length W, two top board reinforcing members and three leg members are formed by cutting fork insertion cutouts (hereinafter, referred to as openings) each having a height h1 and a width w1 in two portions at a predetermined interval in said side plate;

each of said top board reinforcing members is a portion enclosed by a width w1 of said cutout and a height h2 obtained by subtracting a height h1 of said cutout from the width L of said side plate;

each of said leg member is a portion enclosed by the width L of said side plate and a width w3 of leg portions formed on both ends of said side plates or a width w2 of a leg portion formed in a center of said side plate;

said folding lines are arranged such that ridge folding lines and trough folding lines axe arranged alternately;

a W-structure is formed by folding said side plates constituting said W-structure material, alternately in each ridge folding line and each trough line, thus said W-structure comprising said side plates through which two openings pass for insertion of a fork;

a cross section of said W-structure has V-shaped truss structures arranged continuously; and

one or plurality of said W-structures are coated with an adhesive at upper and lower ridge line portions, and inserted and pressed between a top board and a bottom board, to be connected to said top board and said bottom board.
(amended) The pallet according to Claim 1, wherein:

among said folding lines in said W-structure, the ridge folding lines are each a half-cutting line to be bent into "Λ"-shape; and

the trough folding lines are each comprise a full-cutting line and a guideline;
(amended) The pallet according to Claim 1 or 2, wherein:

in the pallet comprising said W-structure, auxiliary members are inserted into said openings for fork insertion, respectively.
(amended) The pallet according to one of Claims 1 ― 3, wherein:

in the pallet comprising said W-structure, a plurality of form retention wings are provided upwardly or right and left from each of said auxiliary member; and

said form retention wings are inserted into corresponding gaps of said openings.
(deleted)
(amended) The pallet according to one of Claims 1 ― 4, wherein:

four peripheries of said top board and four peripheries of said bottom board are provided with side wall flaps having paste margins respectively, to provide the top board having four side wall flaps and the bottom board having four side wail flaps;

each of said top board having four side wall flaps and said bottom board having four side wall flaps is constructed to have fork insertion cutouts in flaps connected in front and rear, correspondingly to said openings in said W-structure;

said paste margins of said top board having four side wall flaps and said bottom board having four side wall flaps are coated with adhesive and bent, and each side flap of said top board having four side wall flaps and said bottom board having four side wall flaps is bent so that the paste margin is pressed onto and fixed to a corresponding side flap, thus forming a lid box and a body box; and

said W-structure coated with an adhesive in ridge lines is contained in said body box, and then, said lid box is put over said body box, so that said body box and said lid box are pressed and fixed to each other.
(amended) The pallet according to one of Claims 1 ― 6, wherein:

in the pallet comprising said W-structure, said top board and said bottom board are each provided with right and left side wall flaps to be a top board having right and left side wall flaps and a bottom board having right and left side wall flaps;

said W-structure is coated with an adhesive in ridge lines and inserted between said top board having right and left side wall flaps and the bottom board having right and left side wall flaps;

thereafter, the side wall flaps of said top board having right and left side wall flaps and said bottom board having right and left side wall flaps are coated with an adhesive and bent, so that corresponding side wall flaps are pressed and fixed to each other.
(amended) The pallet according to one of Claims 1 ― 7, wherein:

in the pallet comprising said W-structure, cutout remnants corresponding to the openings are bent toward the top board while connected to the side plates via the folding lines.
(amended) The pallet according to one of Claims 1 ― 8, wherein:

in the pallet comprising said W-structure, said leg members abutting to said top board are partly cut out to form side plates having beam openings, thus said side plates and said folding lines constituting a W-structure material for four-way insertion;

said W-structure material is folded in the folding lines in the side plates to form a W-structure for four-way insertion;

three of said W-structures are arranged in parallel at suitable intervals;

beam members each made of a sheet of corrugated cardboard are inserted into said beam openings, respectively;

ridge lines in said W-structures for four-way insertion and said beam members abutting said top board and said bottom board are coated with adhesive;

said W-structures for four-way insertion and said beam members are inserted, pressed, and fixed between said top board and said bottom board and pressed so as to form the pallet as a four-way insertion pallet.
(deleted)
(deleted)
(amended) The pallet according to one of Claims 1 ― 9, wherein:

said structure constituting the pallet includes a stiff thin plate such as plastic corrugated cardboard, plastic sheet, joined paper, plywood, ceramic, metal, or the like, as component material.