JPH0891376A - Pallet and manufacturing method thereof - Google Patents

Abstract

(57) Abstract: A pallet in which mechanical strength is improved while reducing weight by reducing bending in the vicinity of an opening into which a fork, which is a mechanically weak portion of a pallet, is inserted. A manufacturing method is provided. SOLUTION: The top plate 3 and the bottom plate 4 are made of a resin or a material including a filler therein, and a large number of ribs are provided so as to connect the top plate 3 and the bottom plate 4. In the pallet 1 in which an opening 7 that is an insertion port into which a fork is inserted is disposed, a rib 11b at least above and below the opening of the pallet 1 is formed in an intersecting shape. Reinforcing plates 10 and 10A connecting the rib ends are arranged on the upper and lower surfaces of the part.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to carrying various articles,
The present invention relates to a pallet used for storage and a method for manufacturing the same, and more particularly to a light weight and high mechanical strength pallet manufactured by using a thermoplastic resin.

[0002]

2. Description of the Related Art Pallets used for transporting and storing various articles are made of wood or thermoplastic resin, but in recent years, they have been made of thermoplastic resin for weight reduction. Is increasing.

The conventional thermoplastic resin pallet (hereinafter, simply referred to as "pallet") is lightweight and
In order to maintain the mechanical strength (for example, compressive strength, bending strength, bending strength, etc.), grid-shaped ribs are formed inside. That is, the above-mentioned conventional pallet has a hollow inside for the purpose of reducing the weight, and a top plate on which an article is placed is reinforced with a grid-like rib to maintain a mechanical strength. ing.

An example of a side sectional view of the above-mentioned conventional pallet is shown in FIG. In the conventional pallet, usually, two pallet plates 2 having the same shape and size are formed by an injection molding method, and the protrusions of these pallet plates 2 are made to face each other and overlap each other. Manufactured by fusing together. The pallet plate 2 formed by the injection molding method forms a high rib 11a having one end fixed to the top plate 3 and the bottom plate 4 and the other end serving as a facing surface, and an opening that is an insertion port into which a fork is inserted. Low ribs for 11
Projections such as b, the partition plate 8a, and the side plate 6a are formed.
The pallets are manufactured by fusing the opposing surfaces of the protrusions such as the high ribs 11a of the two pallet plates 2 to be integrated with each other. The integrated pallet has a low rib 1
The end face portion 1b serves as the opening 7 and serves as an insertion port for inserting the fork. Both end surfaces of the opening 7 serve as partition plates 8 and 8, and the top plate 3 and the bottom plate 4 are connected by a large number of ribs 11. Long side plates and short side plates 6 are formed on the sides of the pallet.

[0005]

FIG. 16 shows the result when the both ends of the pallet described above are fixed and an even load is applied on the pallet top plate 3. The state shown is
Only the left half of the pallet is shown, the pallet being of interest with respect to line C. As shown in the figure, when a uniform load is applied, the pallet is deformed from the vicinity of the side plate 6 which is the fixed end to the vicinity of the central portion C. When the state of this deformation is observed in detail, the amount of deformation is small in the portions where the ribs 11 connecting the top plate 3 and the bottom plate 4 on both sides of the opening 7 are present, and the opening 7
Low rib 11b that is a part, that is, one end is a free end
It can be seen that a large amount of bending occurs in the part.

The present invention has been made in view of the above problems, and reduces bending in the vicinity of an opening into which a fork, which is a mechanically weak portion of a pallet, is inserted.
An object of the present invention is to provide a pallet having improved mechanical strength while maintaining weight reduction, and a manufacturing method thereof.

[0007]

The invention according to claim 1 is made of a resin or a material including a filler in the resin, is provided with a top plate and a bottom plate, and connects the top plate and the bottom plate. A plurality of ribs are provided, and an opening, which is an insertion port into which a fork is inserted, is provided in a part of the rib, a pallet at least above and below the opening in the rib. Form ribs in a cross shape,
A pallet is characterized in that reinforcing plates connecting the rib ends are arranged on the upper surface and the lower surface of the opening. The term “intersecting” means that the ribs intersect in a plan view, and the shape formed by the intersecting ribs may be any polygonal shape such as a square, a rectangle, a triangle, or a hexagon, or may be a curved shape. Further, it is desirable that the ribs formed in a cross shape are arranged over the entire surface of the opening.

According to a second aspect of the present invention, the top plate and / or
Alternatively, the surface of the bottom plate is smooth.
It is the palette described. The invention according to claim 3 is the pallet according to claim 1 or 2, wherein the resin is a thermoplastic resin.

According to a fourth aspect of the present invention, which is made of resin or a material including a filler in the resin, the top plate and the bottom plate are provided, and a large number of ribs are provided so as to connect the top plate and the bottom plate. An opening, which is an insertion port into which a fork is inserted, is disposed in a part of the rib, and ribs of at least upper and lower portions of the opening are formed in an intersecting shape, and the upper surface of the opening and A manufacturing method for manufacturing a pallet in which a reinforcing plate that connects the rib ends is arranged on the lower surface, and the pallet shape is obtained by forming the material by forming the pallet shape with the protrusions facing each other. Two pallet plates are formed on the pallet plate, and one end of the pallet plate is fixed to the top plate or the bottom plate and has a high rib having a cross shape and / or a non-cross shape.
A low cross rib for forming an opening, which is an insertion port into which a fork is inserted, is formed, and a flat plate having a protrusion facing the low rib is formed by molding the material in the same manner. After forming a plate and fitting the reinforcing plate into the opening portion of the pallet plate, the reinforcing plate is integrated with the opening portion of the pallet plate by joining the facing surfaces of the low ribs and the protrusions, A method of manufacturing a pallet, characterized in that the projecting portions of the two pallet plates are arranged so as to face each other, and then the facing surfaces of the two are joined and integrated.

The invention according to claim 5 is the method for manufacturing a pallet according to claim 4, wherein the resin is a thermoplastic resin. The invention according to claim 6 is the method for manufacturing a pallet according to claim 4, characterized in that the pallet plate is molded by a compression molding method.

[0011]

According to the pallet of the first aspect, since crossed ribs are formed on the upper surface and the lower surface of the opening, which is the insertion opening for inserting the fork, and the reinforcing plate for connecting the rib ends is arranged, The rib end of the low rib, which was the free end, is fixed to the reinforcing plate, and its deformation is restrained by the reinforcing plate and the top plate (or the bottom plate). That is, the lower ribs 11b are fixed to the reinforcing plate and the top plate (or the bottom plate) in the opening 7 in the same manner as the deformation is restrained by fixing both ends of the rib 11 to the top plate and the bottom plate. The deformation is restrained by.
For example, by connecting a reinforcing plate of the same material and thickness as the top plate (or bottom plate) to the rib end of the low rib 11b,
When a uniform load similar to the state shown in FIG. 6 is applied, the amount of bending is reduced to about half. Therefore, by providing a reinforcing plate having a slight weight in the opening, mechanical strength such as bending strength and bending strength of the pallet can be significantly improved.

According to the pallet of the second aspect, since the surface of the top plate and / or the bottom plate is smooth, the unevenness derived from the unevenness of the surface of the top plate is not transferred to the article placed on the pallet. According to the pallet of the third aspect, since the resin is thermoplastic, molding is easy, and a high quality pallet in which the size and density are controlled by controlling the temperature is manufactured.

According to the pallet manufacturing method of the fourth aspect, the reinforcing plate is joined to the rib end of the low rib of the pallet plate to integrate them, and then two pallet plates of the same shape and size are joined. Therefore, it is possible to easily manufacture the pallet having the reinforcing plates on the upper surface and the lower surface of the opening, which is the insertion port into which the fork is inserted. In addition, since the reinforcing plate is integrated with the pallet plate by joining, it is possible to provide a pallet manufacturing method with good mass productivity.

According to the pallet manufacturing method of the fifth aspect, since the resin is thermoplastic, molding is easy, and a high quality pallet in which the size and density are controlled by controlling the temperature is manufactured. According to the pallet manufacturing method of claim 6, since the pallet plate is formed by compression-molding the thermoplastic resin, the mold clamping applied to the mold is made as compared with the case where the thermoplastic resin is simply injection-molded. The force can be reduced to about 1/3. Therefore, it is possible to reduce the size and weight of the molding apparatus and manufacture a pallet having a larger size than the conventional one.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a (a) top view, (b) front view, and (c) side view of a pallet according to an embodiment of the present invention. 2A is a sectional view taken along the line AA in FIG. 1, and FIG. 2B is a sectional view taken along the line BB. As shown in FIGS. 1 and 2, the pallet 1 according to this embodiment is a two-way flat pallet and is made of a thermoplastic resin. The pallet 1 has a top plate 3 whose surface is smooth.
Further, it has a flat and substantially rectangular parallelepiped shape including the bottom plate 4, the long side plates 5 and 5, and the short side plates 6 and 6, and both the top plate 3 and the bottom plate 4 can be used.

At predetermined positions of the long side plates 5 and 5, openings 7 and 7 are provided as insertion ports into which forks (not shown) such as a forklift truck used when moving the pallet 1 are inserted. Has been. The opening 7,
7 is from one long side plate 5 toward the other long side plate 5,
That is, they are provided in parallel with each other so as to penetrate the main body of the pallet 1. Further, partition plates 8 for partitioning the opening 7 portion and the interior of the pallet 1 are provided upright on both sides of the opening 7. The position and size of the opening 7 are not particularly limited.

The pallet 1 is formed by stacking two pallet plates 2 and 2 having the same shape and size so as to face each other and joining the facing surfaces of both. Further, a large number of plate-shaped ribs 11 are formed inside the pallet 1 so as to connect the top plate 3 and the bottom plate 4, and the upper and lower portions of the opening 7 are all cross-shaped ribs as will be described later. 11b ... In addition, in FIG. 1 and FIG.
For convenience of explanation, the joint portion is indicated by a line D.

As the thermoplastic resin, for example, polyethylene resin, polypropylene resin, polyamide resin, polyethylene terephthalate resin, acrylonitrile-butadiene styrene (ABS) resin, polyvinyl chloride resin, polycarbonate resin, etc. can be used. It is not limited to these. Further, a modified product or a mixture of these thermoplastic resins, a polymer alloy or the like can also be used. Further, fillers may be added to these thermoplastic resins as required, and additives such as an antioxidant, an ultraviolet ray inhibitor, a colorant, a release agent, and a low-shrinking agent are required. It may be added accordingly.

The above-mentioned thermoplastic resins are, for example, price, affinity with fillers and additives, ease of molding, use and size of pallet 1, mechanical strength required for pallet 1 (for example, compression). Strength, bending strength, flexural strength, etc.) and various physical properties, etc. Of the thermoplastic resins exemplified above, from the viewpoint of mechanical strength required for the pallet 1,
A polypropylene resin such as a homopolymer of propylene or a copolymer of propylene and another monomer is particularly preferable.

The above thermoplastic resin may be used in a non-foamed state, and in order to improve its fluidity and the like,
You may use it in the state foamed about 1.1 times-1.2 times. When the thermoplastic resin is such a foam, compression molding can be performed similarly to a non-foam, and further weight reduction of the pallet 1 can be realized. The above-mentioned filler is blended in order to further improve the mechanical strength of the pallet 1. The filler must have stability to withstand the melting point (Tm) of the thermoplastic resin, and must have a good affinity with the thermoplastic resin,
For example, inorganic fibers such as glass fibers and carbon fibers, inorganic powders such as talc, clay, silica and calcium carbonate are used.

The above-mentioned filler may be appropriately selected depending on, for example, price, affinity with a thermoplastic resin, use and size of the pallet 1, mechanical strength and various physical properties required for the pallet 1. Good. Among the above-mentioned fillers, inorganic fibers, particularly glass fibers, are preferable from the viewpoint of price and mechanical strength required for the pallet 1.

The fiber length of the above-mentioned inorganic fibers is preferably 0.1 mm to 50 mm, although it depends on the kind of fibers to be mixed, and 1
mm to 15 mm is more preferable. Further, the fiber diameter of the inorganic fiber depends on the kind of the fiber to be mixed, but is 1 μm to 50 μm.
Is preferred. The particle size and shape of the inorganic powder are not particularly limited. The blending amount of the filler with respect to the thermoplastic resin depends on the type of the filler to be blended, but from the viewpoint of the mechanical strength required for the pallet 1, it is preferably 50% by weight or less and 10% by weight to 40% by weight. % Is more preferable, and 15% by weight to 35% by weight is further preferable. Also,
Each of the above-mentioned fillers may be mixed in the thermoplastic resin alone, or two or more kinds may be mixed and blended in the thermoplastic resin, if necessary. Furthermore, the method of mixing the thermoplastic resin and the filler is not particularly limited.

As shown in FIGS. 1 and 2, the pallet plate 2 has a top plate 3 (or a bottom plate 4), and pallet plates 2 and 2.
The long side plate 5 that becomes the long side plate 5 when they are overlapped with each other
a, 5a, and short side plates 6a, 6a to be the short side plate 6 are formed in a substantially container shape. Further, the pallet plate 2 is provided with partition plates 8a, 8a serving as partition plates 8 therein, and also has a large number of plate-shaped ribs 11a ... And 11b.

The plate-shaped ribs 11a ..., 11b ... Are formed parallel to the long-side plate 5a and the short-side plate 6a, that is, regularly intersecting in a grid pattern at predetermined intervals, and are vertically arranged on the top plate 3 and The long side plates 5a, 5a and the short side plates 6 are arranged in a row in the bottom plate 4 or a reinforcing plate 10 described later, and are laterally arranged.
a, 6a or partition plates 8a, 8b. The heights of the plate-shaped ribs 11a are equal to the heights of the long side plate 5a and the short side plate 6a.

The heights of the ribs 11b formed in the portions where the openings 7, 7 are provided, that is, the portions sandwiched by the pair of partition plates 8a, 8a, are the same as the dimension of the openings 7 in the height direction. ,
It is lower than the other ribs 11a. The reinforcing plate 10 is fixed on the end faces of the ribs 11b ... Formed between the pair of partition plates 8a, 8a.
The reinforcing plate 10 is fixed to both the upper surface and the lower surface of the opening 7. The reinforcing plate 10 may have the same thickness as the top plate 3 (or the bottom plate 4) or may have a different thickness. Similarly, the material of the reinforcing plate 10 may be the same as or different from that of the pallet plate 2. The reinforcing plate 10 has a low rib 11
It is fixed on the end face of b by joining (described in detail later). The method for manufacturing the reinforcing plate 10 is not particularly limited, and may be, for example, an injection molding method, a compression molding method, or an extrusion molding method.

The above-mentioned plate-like ribs 11a ... When the pallet plates 2 and 2 are superposed on each other, the plate-like ribs 11a, 1 are formed.
1a are formed so as to face each other. That is,
When the pallet plates 2 and 2 are overlapped with each other, the plate-shaped ribs 11a and 11a located at positions opposite to each other are formed to be connected to each other. Therefore, the pallet 1 is
The inside is divided into a large number of independent closed spaces surrounded by a top plate 3, a bottom plate 4, and plate-like ribs 11 ... Which are adjacent to each other.

The number of the plate-like ribs 11 ... Of the pallet 1, that is, the interval between the plate-like ribs 11, 11 is not particularly limited, but the mechanical strength of the pallet 1 becomes smaller as the interval becomes narrower. Is improved, while the weight of the pallet 1 is increased. Therefore, the space between the plate-shaped ribs 11 and 11 can maintain the mechanical strength to the extent that warping, twisting and the like do not occur even when a heavy object is placed on the pallet 1, and also can reduce the weight. As far as possible, the thickness may be appropriately set in consideration of, for example, the thickness of the plate-shaped ribs 11 ...

The thickness of the pallet 1, that is, the top plate 3,
Bottom plate 4, long side plates 5, 5, short side plates 6, 6, plate-shaped rib 11
, And the thickness of the reinforcing plate 10 is such that, even when a heavy object is placed on the pallet 1, the mechanical strength is maintained to the extent that bending or twisting does not occur, and the weight can be reduced. However, it may be set appropriately in consideration of, for example, the amount of the thermoplastic resin used. The thickness of each of the plates 3 to 6, the reinforcing plate 10, the ribs 11, etc. depends on, for example, the type of the thermoplastic resin used, the size of the pallet 1, the use, etc., but a thickness of about 3 mm is sufficient. . Each of the above plates 3 to 6
The thicknesses of the ribs 11, etc. may be the same as each other, or may be different from each other.

In the pallet 1 having the above-mentioned structure, low ribs 11b are provided so as to intersect with each other at the upper and lower portions of the opening 7 which is a mechanically weakest portion, which is an insertion port of a fork. Since the reinforcing plate 10 is fixed to one end of the rib 11b by joining and the other end is fixed to the top plate 3 and the bottom plate 4, the mechanical strength against bending or twisting is significantly improved. Further, regarding the weight surface, the ribs 11b are formed so as to intersect with each other, and the reinforcing plate 10 is added, so that only a slight weight is added. Therefore, the pallet is light in weight as a whole and has sufficient mechanical strength against bending and bending and twisting. Further, since the space defined by the low ribs 11b is hermetically closed, there is no problem that water enters and accumulates inside the pallet.

Further, by forming the surface of the top plate and / or the bottom plate to be smooth, the unevenness derived from the unevenness of the surface of the top plate 3 is transferred to the contact portion of the placed article with the pallet 1. There is no such thing.

The plate-shaped ribs 11a ..., 1 of the pallet plate 2
1b ... may be formed in a slightly tapered shape so that the pallet plate 2 can be easily extracted from the mold when the pallet plate 2 is formed by a molding method described later. In this case, as shown in FIG. 3, the vertical line of the top plate 3 (or the bottom plate 4) and the rib 1
The angle θ formed by 1a (11b) ... Is not particularly limited as long as it does not impair the mechanical strength of the pallet 1, and may be, for example, about 0.5 ° to 5 °.

Further, the top plate 3 surface and the bottom plate 4 of the pallet 1
If necessary, a slip stopper made of rubber, for example, may be attached at a predetermined position on the surface. Further, the top plate 3 surface and the bottom plate 4
The surface may be provided with irregularities or holes as needed. Further, the openings 7 and 7 may be tapered so that a fork (not shown) such as a forklift truck can be easily inserted. In addition, each corner of the pallet 1 may be provided with various reinforcements (for example, increasing the thickness, further forming plate-shaped ribs, etc.) as necessary. In addition, it is also possible to give a so-called R-shape to each corner of the pallet 1.

In the present embodiment, the plate-shaped rib 11 is used.
, 11b have been described as an example in which the long side plates 5 and 5 and the short side plates 6 and 6 are formed in parallel, but the plate-shaped ribs 11 ... 11b ... are the long side plates 5 and 5 and the short side plates. It may be formed obliquely with respect to 6 and 6. Furthermore, the plate-shaped rib 1
1, 11 may be orthogonal to each other as described above, or may be diagonally intersecting with each other. Moreover,
The shape of the lattice formed by the plate-shaped ribs 11 ..., 11b ... is not limited to a square, and may be a triangle, a rectangle (not shown), or the like. Further, the plate-shaped ribs 11 ... Formed in parallel with each other may be all at equal intervals, or if necessary, may be narrowed only at portions requiring strength.

The results of calculating the strength of the pallet of the present invention by structural analysis using the finite element method will be shown below. The models of the pallet plate 2 of the example and the comparative example used this time are shown in FIGS. 4 to 6, and the dimensions are the width L.
= 1100 mm, depth W = 1100 mm, total thickness T =
144mm, the thickness of the plates that make up each part is 3m for the top plate
m, bottom plate 3 mm, reinforcing plate 2 mm, partition plate 2.5 m
m, the rib is 2.5 mm. Opening 7 which is an insertion port
Has its center in the width direction at a position 265 mm from the end, and the width of the opening is 270 mm. The opening department is located in the center in the thickness direction 12, and the height of the opening is 80 mm.
Is. FIG. 4 shows an embodiment of the present invention, in which ribs 11b at the upper and lower portions of the opening 7 are formed to intersect in a lattice pattern,
The reinforcing plate 10 is joined to it. FIG. 5 shows Comparative Example 1
The ribs 11b at the upper and lower portions of the opening 7 intersect, but no reinforcing plate is provided. FIG. 6 shows Comparative Example 2, in which the ribs 11b at the upper and lower portions of the opening 7 do not intersect only in the longitudinal direction, but the reinforcing plate 10 is provided.

The weight of these pallets is as shown in Table 1. In the present invention, the ribs 11b are provided so as to intersect with each other, and the reinforcing plate 10 is provided. For these pallets, first, a structural analysis was performed under the assumption of a JIS standard bending test (JIS Z 0602). This has a width of 100 on each side, as shown in FIG.
The wearer wears a 50 mm thick girdle 50, and a load of 1.25 tons of weight 52 is applied to the bar 51 placed on the opening 7 from above. The model of the deformation at this time (only the left half) is shown in FIG.
Shown in. As a result, as shown in Table 2, in the present invention, the deformation and stress are particularly small in the width direction as compared with the non-reinforcing plate of Comparative Example 1, but in comparison with Comparative Example 2, Only a slight improvement in the longitudinal direction.

Next, structural analysis was conducted under the assumption of a direct placement 4 ton test. This is the load that the bottom pallet receives when four pallets each carrying a load of 1 ton are stacked, and the entire pallet receives the load evenly. A model of the deformation at this time (only the left half) is shown in FIG. As a result, as shown in Table 3, the present invention showed excellent characteristics not only in Comparative Example 1 but also in Comparative Example 2 in both the longitudinal direction and the width direction.

Table 1 Composition Weight (kg) The present invention Cross rib + Reinforcement plate 14.9 Comparative example 1 Cross rib (without reinforcement plate) 12.8 Comparative example 2 Parallel rib + reinforcement plate 14.3

Table 2 JIS standard bending test W-direction deflection W-direction stress L-direction deflection L-direction stress (mm) (kgf / cm ² ) (mm) (kgf / cm ² ) Invention 14.7 76 4.3 53 53 Comparison Example 1 26.3 250 4.7 57 Comparative Example 2 14.9 84 4.5 56

[0040]

Next, a method of manufacturing the pallet 1 having the above structure will be described below with reference to FIGS. In the following description, the pallet plates 2 and 2 are formed by an injection compression molding method which is a kind of compression molding method.

First, as shown in FIG. 10 (a), in a state in which the female side mold 21 and the male side mold 22 in which the cavity, which is the space for forming the pallet plate 2, is formed in the gap are opened. As shown in FIG. 2B, a predetermined amount of molten raw material resin (thermoplastic resin) 20 is supplied into the cavity.

The female die 21 is a movable die and is arranged above the male die 22. The male die 22 is a fixed die, and its mirror surface portion has
Side plates 5a, 6a and ribs 11a ..., 11b of the pallet plate 2
A protrusion corresponding to a shape such as ... Is formed. Further, the male die 22 has a molten resin passage 22 provided therein.
It is connected to a molten resin injection device (not shown) via a.

By supplying the raw material resin 20 into the cavity from the injection device through the molten resin passage 22a, the productivity and working efficiency of the pallet plate 2 can be improved.

When the raw material resin 20 is supplied into the cavity, as shown in FIG. 11A, the molds 21 and 22 are clamped with a predetermined mold clamping force, and the molten resin is shaped into a predetermined shape. . After that, the shaped molded product is cooled, and the molds 21 and 2 are cooled.
2 is opened and the pallet plate 2 is taken out as shown in FIG. The molds 21 and 22 may be clamped while supplying the raw material resin 20 into the cavity.

By the injection compression molding method described above, the surface of the top plate 3 (and / or the surface of the bottom plate 4) of the pallet plate 2 can be made smooth. Further, even a pallet plate 2 having a width exceeding 1 m can be easily formed.

The method of molding the pallet plate 2 is not limited to the above-mentioned injection compression molding method, and for example, the molds 21 and 22 may be horizontally opened and clamped.
Generally, when the cavities have the same size, the mold clamping force in the compression molding method can be set to about 1/3 of the mold clamping force in the injection molding method.

The method of supplying the raw material resin 20 into the cavity is not limited to the above method. For example, a thermoplastic resin sheet is formed in advance, the sheet is heated in an infrared heating furnace or the like to a temperature not lower than the melting point and does not cause liquid dripping, and then the sheet is put into the molds 21 and 2.
When the mold 2 is opened, it may be placed in the cavity and then compression molded.

Next, a method of joining the reinforcing plate 10 to the pallet plate 2 will be described with reference to FIG. As shown in FIG. 12A, the reinforcing plate 10 is a flat plate, and its material, thickness, and the like are the same as those of the top plate 3, the bottom plate 4, or the rib plate 11.
The reinforcing plate 10 has a partition plate 8a as shown in FIG.
Is inserted along with and is fixed to the end surface of the rib 11b with an adhesive. The side surface 10a of the reinforcing plate may also be fixed to the side surface of the partition plate 8a with an adhesive as well. As the adhesive, for example, an ethylene / vinyl acetate resin-based adhesive, an Epokin resin-based adhesive, or the like can be used depending on the materials of the reinforcing plate 10 and the pallet plate 2.

Next, according to FIG. 13, a reinforcing plate 1 provided with protrusions.
A method of joining 0A to the rib 11b will be described. First, the reinforcing plate 10 having the protrusions 13 as shown in FIG. 13A is prepared. The protrusion 13 is formed integrally with the reinforcing plate 10 and is arranged so as to face the rib 11b fixed to the top plate 3 (bottom plate 4). The shape of the end surface is the same as and the same as the rib 11b. The method of manufacturing the reinforcing plate provided with the protrusions is not particularly limited, and may be performed by, for example, the injection compression molding method similarly to the molding method of the pallet plate 2, or by the normal injection molding method. Is also good.

Next, as shown in FIG.
On the end face of b, the heat plate 41 is arranged with a slight distance, and the reinforcing plate 10A is inserted into the opening along the partition plate 8a. The heating plate 41 is a heater covered with a metal plate such as a copper plate or an aluminum plate, and is movable in a direction perpendicular to the paper surface. The heating plate 41 heats both the end faces of the protrusions 13 of the reinforcing plate 10A and the end faces of the low ribs 11b of the pallet plate 2 to a temperature slightly higher than the melting point of the thermoplastic resin. And
When the end faces of the protrusion 13 and the rib 11b facing each other are melted, the hot plate 41 is pulled out, and pressure is applied to the reinforcing plate 10A from above to join them.

(C) shows a stage in which the reinforcing plate 10A is joined to the pallet plate 2. Then, the side end surface 1 of the reinforcing plate 10A
0a and the partition plate 8a may be bonded by an adhesive. In this way, the reinforcing plate 10A becomes the pallet plate 2
Is integrally fixed to. The apparatus used for joining is the same as the one used for joining the pallet plates 2 described below, and the details of the joining method are described below.

(D) shows another embodiment of those shown in (b) and (c) above. (D) is a method of joining all the reinforcing plates 10A to the ribs 11b without using an adhesive. Specifically, similar to (b) above, the heating plate 4
In method 1, the end face of the protrusion 13 of the reinforcing plate 13a and the end face of the low rib 11b of the rib plate are both heated, and the both are joined.

Next, as shown in FIG. 14, the two pallet plates 2 and 2 formed as described above are held by a pair of upper and lower holding devices 31 and 32 and are opposed to each other at a predetermined interval. Let That is, the tops 3 and bottom plates 4 of the pallet plates 2 and 2 are held by the holding devices 31 and 32, and the pallet plates 2 and 2 are held.
The long side plates 5a, 5a, the short side plates 6a, 6a, the plate-shaped ribs 11a, etc. are positioned and arranged so as to face each other.

The holding devices 31, 32 are suction pipes 31a, 3 connected to a suction means (not shown) such as a vacuum pump.
2a, and the pallet plates 2, 2 are sucked by suction means through the suction pipes 31a, 32a.
Is adsorbed and held at a predetermined position. The upper holding device 31 is movable in the vertical and horizontal directions. Note that, instead of making the holding device 31 movable, the lower holding device 32 may be made movable in the vertical and horizontal directions.

Next, after the pallet plates 2 and 2 which are held vertically are positioned, the heater 43 and the copper plate or aluminum plate are kept between the pallet plates 2 and 2 so as not to come into contact with them. The hot plate 41 including the metal plate 42 and the like is inserted. The heat plate 41 is movable in the horizontal direction and is heated to a temperature slightly higher than the melting point of the thermoplastic resin forming the pallet plates 2 and 2. Therefore, the opposing surfaces of the pallet plates 2 and 2 are heated and melted by the heat of the hot plate 41. The pallet plates 2 and 2 are
The distance between the heat plate 41 and the heat plate 41 is not particularly limited.
Also, the heating time by the heating plate 41 is not particularly limited. The hot plate 41 may be heated to a predetermined temperature after being inserted between the pallet plates 2 and 2.

When the opposing surfaces of the pallet plates 2 and 2 are sufficiently melted, the heat plate 41 is pulled out from between the pallet plates 2 and 2,
The pallet plates 2 and 2 are brought into contact with each other. As a result, the pallet plates 2 and 2 are long side plates 5a, 5a and short side plates 6 of each other.
The a, 6a, the partition plates 8a, 8a, the plate-shaped ribs 11a, ... Are joined and integrated to complete the pallet 1.

The molten state of the facing surfaces of the pallet plates 2 and 2 is preferably stopped to such an extent that the pallet plates 2 and 2 can be sufficiently joined to each other. If the above facing surfaces are melted more than necessary, the long side plates 5a, 5a, the short side plates 6a, 6
The dimensions of a, the partition plates 8a, 8a, and the plate-shaped ribs 11a ... Are nonuniformly shortened, and their shapes are collapsed. And
As a result, the pallet 1 having a predetermined shape and size cannot be manufactured, and a predetermined mechanical strength cannot be obtained, which is not preferable.

Further, the pressing force of the holding devices 31 and 32 when the pallet plates 2 and 2 are brought into contact with each other depends on the degree of melting of the facing surfaces, but it does not impair the external appearance of the joining portion.
0.2 kg / cm ² or more, 10 kg / cm ² or less, preferably 0.2 kg / cm ² or more, may be set to 5 kg / cm ² or less.
Alternatively, the upper pallet plate 2 may be pressed and joined by its own weight.

Further, in the above-mentioned manufacturing method, the heat fusion method in which the mutually facing surfaces of the pallet plates 2 and 2 are joined by heating with the hot plate 41 has been described as an example.
Instead of using the heat fusion method, for example, a pallet plate 2,
By oscillating 2 rub against each other,
A vibration fusion method may be used in which the frictional heat generated thereby is used for joining. Alternatively, the pallet plates 2 and 2 may be joined together by a known method other than the above heat fusion method or vibration fusion method, for example, bolting or an adhesive agent.

It should be noted that the pallet 1 was prepared by using the above vibration fusion method.
When manufacturing the above, first, the pallet plates 2 and 2 are positioned and arranged so that the long side plates 5a, 5a, the short side plates 6a, 6a, etc. of the pallet plates 2, 2 come into contact with each other. Then, in this state, the pallet plates 2 and 2 are slightly vibrated at a high speed (for example, reciprocally moved in a horizontal direction with a width of 50 microns) and rubbed against each other, and the opposing surfaces are heated by frictional heat generated by friction. Melt. As a result, the pallet plates 2 and 2 are joined together and integrated to form the pallet 1. The pressing force at the time of contacting the pallet plate 2,2, depending on the type of degree and the thermoplastic resin of said minute vibration, 0.2 kg / cm ² or more, 10 kg / cm ² or less, preferably 0. It should be ² kg / cm ² or more and 5 kg / cm ² or less. Alternatively, the upper pallet plate 2 may be pressed by its own weight.

Next, the pallet 1 will be described more specifically with reference to an example. In the following description, width 1800mm, depth 1400mm, height 120mm
The case where the pallet 1 of 1 is manufactured is shown. In addition, the distance between the plate-shaped ribs 11, 11 that are parallel to each other is 90 mm in the width direction, 87.5 mm in the depth direction, and the opening 7 that is the insertion port of the fork is 270 mm × 60 mm.
, The bottom plate 4, the ribs 11a, ..., 11b, and the reinforcing plate 10 have a thickness of 3 mm. Further, the plate-shaped ribs 11 and 11 are orthogonal to each other so that the lattice formed is rectangular, and are also orthogonal to the side plates 5, 5, 6, and 6.

First, the temperature is kept at 50 ° C. by passing hot water through the temperature control pipes in which the female mold 21 and the male mold 22 are arranged in the respective molds, and the mold is opened, and the molten state is maintained in the cavity. 30 kg of polypropylene resin (Temperature 250 ° C.) (Sumitomo Chemical Co., Ltd .: trade name Sumitomo Noblen AH561) is melted from the injection device 22
supplied via a. Next, almost at the same time as the supply of the polypropylene resin into the cavity is completed, the mold 2
The molds 1 and 22 were clamped with a mold clamping force of about 2000 t and maintained in this state for a predetermined time. Next, after cooling the molded product while maintaining the above mold clamping force, the molds 21 and 22 were opened, and the pallet plate 2 was taken out. Then, the above molding method was repeated to obtain two pallet plates 2 and 2.

By the same procedure, 270 mm × 60 mm × 3
A mm reinforcing plate 10A is manufactured, and the reinforcing plate 10A is provided with protrusions 13 facing the low ribs 11b. Then, the low ribs 11b and the end faces of the protrusions 13 of the reinforcing plate are joined and integrated by a heat fusion method or a vibration fusion method.

Subsequently, the two pallet plates 2 and 2 are held by the holding devices 31 and 32 so that the long side plates 5a and 5a and the short side plates 6a and 6a of the pallet plates 2 and 2 face each other. Positioned and placed. Then, a hot plate 41 having a temperature of 250 ° C. was inserted between the pallet plates 2 and 2. After the opposing surfaces of the pallet plates 2 and 2 are sufficiently melted, the heat plate 41 is pulled out from between the pallet plates 2 and 2, and the pallet plates 2 and 2 are brought into contact with each other and pressed with a pressing force of 1 kg / cm ^2. It was joined.
While maintaining this state, the pallet plates 2 and 2 were cooled and integrated to obtain a pallet 1.

The pallet 1 obtained by the above-described manufacturing method did not cause bending, twisting, bending or the like much when compared with a conventional pallet even when an article having a weight of about 1 t was placed.

As described above, the pallet 1 is manufactured by compression-molding the raw material resin 20 so that the pallet 1 is formed into two pallet plates 2 of the same shape and the same size when they are overlapped with each other so as to face each other. Form 2. Therefore, as compared with the case where the raw material resin 20 is injection-molded, the mold 21,
Since the mold clamping force applied to 22 can be reduced,
It is possible to manufacture the pallet 1 having a larger size than the conventional one. This maintains a predetermined mechanical strength, and
It is possible to manufacture the pallet 1 whose weight is reduced.

The size of the pallet 1 manufactured by the above manufacturing method is, for example, 1800 mm in width and 1400 in depth.
mm, height can be about 120 mm,
It is not particularly limited. Also, the type and shape of the articles transported and stored on the pallet 1 are not particularly limited. In the pallet 1, the top plate 3 surface and the bottom plate 4 surface are smooth, and since the unevenness derived from the unevenness of the top plate 3 surface is not transferred to the contact portion of the placed article with the pallet 1, For example, carry paper such as corrugated board
Suitable for storage.

In the present embodiment, the two-way pallet 1 is described as an example, but the pallet according to the present invention may be a four-way pallet. Further, although the flat pallet has been described as an example in the present embodiment, the pallet according to the present invention may be a box pallet or a post pallet.

[0070]

As described above, in the pallet of the present invention, cross ribs are formed on the upper surface and the lower surface of the opening which is the insertion port for the fork, and the reinforcing plate connecting the rib ends is arranged. It was done. Therefore, the ribs around the opening are connected between the reinforcing plate and the top plate or the bottom plate,
Deformation at the pallet opening is restrained against pressing force such as bending, bending, and twisting of the pallet. Therefore, the opening, which is a weak point of the conventional pallet, is reinforced, and the deformation such as bending, bending, and twisting of the entire pallet becomes extremely small. Therefore, the mechanical strength can be improved while maintaining the weight reduction by adding the reinforcing plate having a slight weight. Further, since the structure around the opening, which is the insertion port of the forklift, is sealed by the reinforcing plate, there is no problem that water enters and accumulates in the pallet.

If the pallet is allowed to flex and twist to some extent, the top plate, the bottom plate, the rib plate, etc. can be made thinner to achieve a lighter weight.

Further, since the surface of the top plate and / or the bottom plate is smooth, the unevenness derived from the unevenness of the surface of the top plate and / or the bottom plate is transferred to the contact portion of the placed article with the pallet. The effect is that there is no.

Further, according to the pallet manufacturing method of the present invention, it is possible to easily manufacture the pallet having the reinforcing plates on the upper and lower surfaces of the opening which is the insertion port of the fork. Then, by joining the reinforcing plate having the protrusions to the end faces of the low ribs, it is possible to provide the above-described pallet manufacturing method with favorable mass productivity.

By using the compression molding method for molding the pallet plate, the mold clamping force can be reduced to about 1/3 of that of the conventional injection molding method. Therefore, it is possible to manufacture a pallet having a size larger than that of the conventional one.

[Brief description of drawings]

FIG. 1A is a top view of a pallet according to an embodiment of the present invention,
It is a front view and (c) side view.

2A is a sectional view taken along the line AA in FIG. 1, and FIG. 2B is a sectional view taken along the line BB.

FIG. 3 is a partial cross-sectional view showing a taper of a rib plate.

FIG. 4 is a diagram showing a model of the configuration of the present invention.

FIG. 5 is a diagram showing a model of a conventional example.

FIG. 6 is a diagram showing a model of another conventional example.

FIG. 7 is a diagram showing a pallet load test method.

FIG. 8 is a diagram showing simulation results of the test of FIG.

FIG. 9 is a diagram showing simulation results of another test.

FIG. 10 is an explanatory diagram showing an injection compression molding method.

FIG. 11 is an explanatory diagram showing an injection compression molding method.

FIG. 12 is an explanatory diagram showing a method of adhering a reinforcing plate.

FIG. 13 is an explanatory diagram showing a method of joining reinforcing plates.

FIG. 14 is an explanatory diagram showing a method of joining two pallet plates.

FIG. 15 is a sectional view of a conventional pallet.

16 is an explanatory diagram showing a deformed state when a uniform load is applied to the pallet shown in FIG.

[Explanation of symbols]

 1 pallet 2 pallet plate 3 top plate 4 bottom plate 5 long side plate 6 short side plate 7 opening for fork insertion 8 partition plate 10, 10A reinforcing plate 11, 11a high rib 11b low rib

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Nagaoka 1-5 Anezaki Kaigan, Ichihara City, Chiba Sumitomo Chemical Co., Ltd.

Claims (6)

[Claims] 1. A top plate and a bottom plate, which are made of resin or a material including a filler therein, are provided with a number of ribs so as to connect the top plate and the bottom plate, and one of the ribs is provided. In a pallet in which an opening, which is an insertion port into which a fork is inserted, is provided, the ribs of at least the upper side and the lower side of the opening in the rib are formed in an intersecting shape, and the opening is formed. A pallet characterized in that reinforcing plates connecting the rib ends are arranged on the upper and lower surfaces. 2. The pallet according to claim 1, wherein the surfaces of the top plate and / or the bottom plate are smooth. 3. The pallet according to claim 1, wherein the resin is a thermoplastic resin. 4. A resin or a material including a filler therein, which is provided with a top plate and a bottom plate, and a plurality of ribs are provided so as to connect the top plate and the bottom plate, and one of the ribs is provided. An opening, which is an insertion port into which a fork is inserted, is arranged in the portion, and ribs of at least upper and lower portions of the opening are formed in an intersecting shape, and the rib ends are formed on the upper surface and the lower surface of the opening. A manufacturing method for manufacturing a pallet in which reinforcing plates that are connected to each other are arranged. By molding the above material, two pallet plates of the same shape and size that become a pallet shape when the protrusions face each other and are overlapped The pallet plate is formed with high ribs of a cross shape and / or a non-cross shape, one end of which is fixed to a top plate or a bottom plate, and a low cross for forming an opening portion into which a fork is inserted. Ribs are formed Similarly, a reinforcing plate, which is a flat plate having a projection facing the low rib, is formed by molding the material, and after the reinforcing plate is fitted into the opening portion of the pallet plate, the low rib and the projection are formed. The reinforcing plates are integrated with the opening portions of the pallet plate by joining the facing surfaces of the two pallet plates, and the projecting portions of the two pallet plates are arranged so as to face each other, and then the facing surfaces of the two pallet plates are joined to form an integral body. A method for manufacturing a pallet, characterized by: 5. The method of manufacturing a pallet according to claim 4, wherein the resin is a thermoplastic resin. 6. The method of manufacturing a pallet according to claim 4, wherein the pallet plate is molded by a compression molding method.