JPH06179448A - Plastic pallet and production thereof and metallic mold - Google Patents

Abstract

PURPOSE:To provide a plastic pallet and production method thereof and a metallic mold by which a light and highly rigid and an inexpensive plastic pallet can be produced and the dimensions thereof can be easily changed. CONSTITUTION:After the upper deck 13 and the lower deck 14 having a flat cylindrical body with the bottom and the rib lattice structure in the respective insides are molded by a metallic mold respectively, these opening faces are joined to each other by fusing through a specified welding margin to form a plate deck 12. And after a girder 30 is molded like a flat cylindrical body with the bottom and the rib lattice structure, the opening is turned downward and joined to the rear face of the deck 12 by fusing through a specified welding margin to form an assembling type pallet 10. In this time, the pallet size can be changed by use of a variable length metallic mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin pallet, a method of manufacturing the same, and a molding die, and can be used for a two-way fork type synthetic resin pallet.

[0002]

BACKGROUND ART Conventionally, various materials such as wood, metal, and synthetic resin have been used as pallets for carrying products such as products, but they are lightweight and excellent in durability. Therefore, recently, pallets made of synthetic resin are often used. Such pallets include two-way fork type and four-way fork type, depending on the direction in which the arms of the forklift are inserted, and whether the loading surface is formed on both sides of the pallet or only one side. Depending on the type, there are double-sided type and skid type. FIG. 9 shows an example of a skid type synthetic resin pallet 90 with a two-way fork (first conventional example). The pallet 90 has a plate-shaped deck portion 92 having a mounting surface 91 on which an article such as a product is placed, and three square bar-shaped girder portions 93 are provided on the back surface side of the deck portion 92.
Is provided. Between the three girder portions 93, there is an insertion portion 94 into which the arm of a forklift or the like is inserted. The deck portion 92 and the three girder portions 93 are integrally formed of synthetic resin. A large number of reinforcing ribs are provided on the back surface of the deck portion 92. In such a two-way insertion type pallet 90, the deck portion 92 bears the strength in the W direction in the figure, while the three girder portions 93 bear the strength in the L direction in the figure.

There is also an example of a synthetic resin pallet 80 as shown in FIG. 10 (see JP-A-60-148452; second conventional example). 10 (A) is a plan view of the pallet 80, and FIG. 10 (B) is a sectional view thereof. Pallet 80
Has deck sections 81, 82 on both sides and these deck sections 8
1, 82 are double-sided type pallets connected by girders 83, and each deck 81, 82 has two plate-shaped parts 8 respectively.
The structure has four and 85 and reinforcing ribs 86 that are separately arranged in the vertical and horizontal directions to connect them. Each deck section 8
1, 82 and girder portion 83 are joined by heat welding.

[0004]

However, in the pallet 90 of the first conventional example described above, the strength of the girder portion 93 is different from that of the girder portion 93.
Is higher due to the combination of the deck section 92 with the deck section 92.
The plate has only the deck portion 92 and has a low bending rigidity, and as a result, the strength in the L direction in FIG. 3 is considerably higher than the strength in the W direction in FIG. Therefore, in order to improve the strength in the W direction, many reinforcing ribs must be provided on the back surface of the deck portion 92, which increases the overall weight of the pallet 90 and also forms such a large number of ribs. However, there is a problem that the processing cost of the mold becomes high. Further, in such a pallet 90, since the deck portion 92 and the girder portion 93 are integrally molded, the size of the pallet 90 can be changed by remaking a mold or by combining the mold blocks as a whole. However, there is a problem in that complicated work for reassembling is required, which is troublesome and costly.

Further, the pallet 80 of the second conventional example described above.
Then, each deck part 81, 82 has two plate-like parts 84,
The laminated plate structure of 85 is provided and the reinforcing ribs 86 are provided, so that high strength can be obtained to some extent. However, since the ribs 86 are separately arranged vertically and horizontally, there is a problem that the required strength cannot be secured if the number of ribs 86 is significantly reduced. Further, in such a vertical and horizontal arrangement of the ribs 86, the arrangement pattern of the ribs is not uniform over the entire surface of the pallet 80. Therefore, in order to change the size of the pallet 80, a number corresponding to each size is used. There is a problem that a mold is required and the cost is high.

An object of the present invention is to provide a synthetic resin pallet which is lightweight, highly rigid and inexpensive to manufacture, and whose size can be easily changed, a manufacturing method thereof and a molding die.

[0007]

SUMMARY OF THE INVENTION The present invention is intended to achieve the above object by improving the rigidity of the deck portion by forming the deck portion in the shape of a laminated plate having a rib lattice structure. Specifically, the present invention is a synthetic resin pallet comprising a deck portion having a loading surface formed on the upper surface, and a girder portion provided on the back surface side of the deck portion, wherein the deck portion is An upper plate-like portion forming the object surface, a lower plate-like portion provided substantially parallel to the upper plate-like portion and forming a back surface of the deck portion, and the upper plate-like portion and the lower plate-like portion A rib lattice structure in which ribs connecting the above are crossed with each other, and a large number of closed spaces are formed by each lattice of the rib lattice structure and the upper plate-shaped portion and the lower plate-shaped portion. And

Here, the deck portion is formed by joining two flat bottomed cylindrical bodies each having a rib lattice structure inside with their opening surfaces joined to each other, and the girder portion is formed by the two existing bottom portions. It is preferable that a flat bottomed cylinder, which is separate from the bottom cylinder and has a rib lattice structure inside, is joined to the back surface of the deck portion with its opening surface facing downward.

Further, the present invention is a method for manufacturing a synthetic resin pallet comprising a deck portion having an upper surface on which a loading surface is formed, and a girder portion provided on the back surface side of the deck portion. After the deck part is divided into two flat bottomed cylinders each having a rib lattice structure inside by a molding die, the opening surfaces of these are joined together by heat welding via a predetermined welding margin. The girder portion is formed into a flat bottomed cylindrical body that is separate from the two bottomed cylindrical bodies and has a rib lattice structure inside, and then the opening surface thereof is formed. Is directed downward and is joined to the back surface of the deck portion by heat welding through a predetermined welding margin.

Here, the mold for molding a synthetic resin pallet used in this manufacturing method comprises a core member formed by combining an arbitrary number of unit blocks and a cavity member corresponding to this core member. It is desirable to have.

[0011]

According to the present invention as described above, the upper plate-like portion which forms the loading surface, the lower plate-like portion which is provided substantially parallel to the upper plate-like portion and forms the back surface of the deck portion, and the upper plate-like portion above these are provided. A deck portion is formed by a rib lattice structure that connects the side plate portion and the lower plate portion. For this reason, the deck portion is formed into a laminated plate shape including the upper plate-shaped portion and the lower plate-shaped portion, so that the strength of the deck portion can be improved and the number of ribs can be reduced. Become. Also, since the ribs are arranged in a grid pattern, it is easy to secure the strength, so that the number of ribs can be reduced, so that the pallet as a whole can be made lightweight and highly rigid. become.

Further, in manufacturing the synthetic resin pallet according to the present invention, the deck portion is formed by joining two separately molded flat bottomed cylindrical bodies having a rib lattice structure inside the girder portion. The pallet size can be easily changed by forming the pallet by a bottomed cylindrical body that is a separate body from these two bottomed cylindrical bodies, and by assembling the deck part and the girder part to form a pallet. Therefore, the number of molding dies can be reduced as compared with the case where the pallets are individually prepared corresponding to each size, and the cost can be reduced. Then, by making the deck part of such a split-joint type, the above-mentioned laminated plate structure can be easily realized.

Further, in manufacturing the synthetic resin pallet, a molding die having a core member formed by combining an arbitrary number of unit blocks and a cavity member corresponding to the core member is used. Then, the following manufacturing method becomes possible. That is, by changing the number of unit blocks forming the core member,
By changing the size of the core member and correspondingly changing the size of the cavity member, it is possible to form deck parts and girder parts of different sizes, and the entire pallet becomes free size. Further, by forming a grid-like groove corresponding to the rib grid structure on the unit block forming the core member and preparing a plurality of types of unit blocks having different widths or intervals of the groove, a deck portion having different strength or It becomes possible to form the girder portion, and it becomes possible to adjust the strength of the entire pallet, thereby achieving the above object.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall structure of a pallet 10 according to this embodiment. The pallet 10 has three plate-shaped deck portions 12 each having a loading surface 11 on which an article such as a product is placed.
On the back side of these three deck parts 12, three square bar-shaped girder parts 30 are formed so as to connect the three deck parts 12 in a direction perpendicular to the longitudinal direction of each deck part 12. It is provided. Between the three girder portions 30, there is an insertion portion 40 into which the arm of a forklift or the like is inserted. Such a pallet 10
Is a so-called skid type in which the loading surface 11 is formed on only one side of the pallet 10, and is a two-way fork type fork into which the arms of a forklift can be inserted from two directions of the pallet 10.

The deck portion 12 is constructed by joining an upper deck portion 13 and a lower deck portion 14 in the form of two laminated plates. 2 and 3 show the upper deck portion before joining.
13 and lower deck portion 14 are shown. Upper deck part
Both the lower deck portion 13 and the lower deck portion 14 are flat-bottomed bottomed tubular bodies each having a rib lattice structure 20 in which vertical and horizontal ribs intersect each other, and the bottom portions thereof are an upper plate-shaped portion 17 and a lower plate-shaped portion, respectively. 18 and the opposite side of each is the opening surface
It is 15 and 16. Both the upper deck portion 13 and the lower deck portion 14 are made of synthetic resin such as polypropylene (PP), and are formed by injection molding including the internal rib lattice structure 20. Upper deck 13 and lower deck 14
The length in the longitudinal direction (W direction in FIG. 2) is variable by the molding die 50 described later, and the width B is about 50 mm to 500 mm and the height dimension H is about 12.5 mm to 37.5 mm. Is.
Of the height H, about 2.5 mm on each side of the opening surfaces 15 and 16 (Fig. 3
The middle S part) is the welding margin.

In the state of FIG. 1, the upper deck portion 13 and the lower deck portion 14 are joined by heat welding the welding margin. The heat welding is usually performed by hot plate welding in which the welding margins on both sides of the upper deck portion 13 and the lower deck portion 14 are preliminarily applied to a heating plate (heater) to soften them, and both sides are crimped. Also, after heat welding, the welding margins on both sides are almost eliminated. Then, in the state after joining, the upper plate-shaped portion 17 of the upper deck portion 13 forms the mounting surface 11, and the lower plate-shaped portion 18 of the lower deck portion 14 forms the back surface of the deck portion 12. ing.

FIG. 4 shows a state before joining the deck portion 12 and the girder portion 30. The girder portion 30 is, like the upper deck portion 13 and the lower deck portion 14, a flat rectangular bottomed cylindrical body having a rib lattice structure 20 in which vertical and horizontal ribs intersect each other, and the side opposite to the bottom portion. The surface of is an opening surface 31. The girder portion 30 is made of a synthetic resin such as polypropylene (PP), and is formed by injection molding including the rib lattice structure 20 inside. The length of the girder portion 30 in the longitudinal direction (L direction in FIG. 1) is variably configured similarly to the length of the upper deck portion 13 and the lower deck portion 14 in the longitudinal direction (W direction in FIG. 1) described above. ing.

The opening surface 31 of the girder portion 30 is a bottom surface, that is, a grounding surface in a state after the deck portion 12 and the girder portion 30 are joined. 2.5 mm to the back surface of the deck portion 12, that is, the outer surface of the lower plate-shaped portion 18 of the lower deck portion 14.
A welding substitute protrusion 60 having a height of about 10 mm is provided, and on the other hand, on the upper surface of the girder portion 30 (the surface opposite to the opening surface 31), a position corresponding to the arrangement of the welding substitute protrusion 60 is provided. A welding substitute protrusion 61 of the same size is provided. These welding substitute projections 60, 61 are provided by forming grooves at predetermined positions on the inner surface of a nesting frame-shaped block mold 52 of a molding mold 50, which will be described later. The deck portion 12 and the girder portion 30 are heat-welded (usually to a hot plate) via the welding substitute protrusions 60 and 61, as in the case of joining the upper deck portion 13 and the lower deck portion 14 described above. It is designed to be joined by welding. After heat welding, the welding substitute protrusions 60 and 61 are almost eliminated.

FIG. 5 shows a so-called nest incorporated in a molding die 50 for injection molding the upper deck portion 13 and the lower deck portion 14. This nest contains a male rib (core block) nesting rib lattice block mold
There are a mold 51 and a nested frame-shaped block mold 52 which is a female mold (cavity block). FIG. 6 shows a cross section of a state in which the nesting rib lattice block mold 51 and the nesting frame block mold 52 are combined. In FIGS. 5 and 6, the nesting rib lattice block mold 51 is a unit block having a predetermined size, and an arbitrary number of unit blocks are combined to form the core 53. Therefore, the cores 53 having different sizes can be formed in block units. This nesting rib lattice block mold
The 51 is provided with lattice-shaped grooves 54 corresponding to the rib lattice structure 20 formed inside the upper deck portion 13 and the lower deck portion 14. The nesting frame-shaped block mold 52 is formed in a frame shape surrounding the outside of a core 53 formed by the nesting rib lattice-shaped block mold 51, and has a predetermined cavity between the nesting rib-shaped block mold 51 and the nesting rib-shaped block mold 51. 55 to form. This nested frame block mold 52 has a core 53
A plurality of blocks having different sizes are prepared so as to be able to cope with the change in size.

FIG. 6A shows a combination of a two-unit nesting rib lattice block mold 51 and a corresponding two-unit nesting frame-shaped block mold 52, and FIG. 6B. In, a combination of three-unit nesting rib lattice block mold 51 and a corresponding three-unit nesting frame-shaped block mold 52 is shown, and the same is true for more units.
In this way, the molding die 50 is configured to be variable in the longitudinal direction (W direction in FIG. 1) of the upper deck portion 13 and the lower deck portion 14.

A molding die for injection-molding the girder portion 30 also has such an upper deck portion 13 and a lower deck portion.
It has the same structure as the molding die 50 of 14, and includes a nesting rib lattice block die and a nesting frame block die, and is variable in the longitudinal direction of the girder portion 30 (L direction in FIG. 1). It is configured.

In this embodiment, the pallet 10 is manufactured as follows. First, the nesting rib lattice-shaped block mold 51 and the nesting frame-shaped block mold 52 are incorporated in the molding die 50 of the upper deck part 13 and the lower deck part 14, and the upper deck part 13 and the lower deck part 14 are Injection molding is performed by the molding die 50. At this time, the core 53 is formed by combining the nesting rib lattice block molds 51 in the number (unit) corresponding to the length W of the upper deck portion 13 and the lower deck portion 14 to be molded, and correspondingly. Select the nesting frame-shaped block mold 52 of the size to be used. Similarly, the girder portion 30 is also injection-molded with a molding die including a nesting rib lattice-shaped block die and a nesting frame-shaped block die. Next, the upper deck portion 13 and the lower deck portion 14 are connected to the respective opening surfaces 15,
The deck portion 12 is formed by joining the 16 together by heat welding. After that, the deck portion 12 and the girder portion 30 are joined by thermal welding through the welding substitute protrusions 60 and 61 to complete the production of the pallet 10.

According to this embodiment, the following effects are obtained. That is, the upper deck portion 13 and the lower deck portion 14, which are flat-angled bottomed cylindrical bodies having the rib lattice structure 20 inside, are joined by aligning the respective opening surfaces 15 and 16, and the upper plate portion 17 and the lower plate portion 17 are joined together. Since the side plate-like portion 18 and the deck portion 12 having a structure joined to each other through the rib lattice structure 20 in a laminated plate shape are formed, it is 1.5 to 2 times as large as a deck portion having the same thickness when there is no alignment. It is possible to obtain a degree of rigidity. For this reason, it is possible to eliminate the inconvenience that many reinforcing ribs must be provided on the back surface of the deck portion 92 in order to secure the strength like the pallet 90 of the first conventional example described above.
The pallet 10 can be made lightweight as a whole.

Further, since the pallet 10 is of an assembly type in which the deck portion 12 and the girder portion 30 are individually molded and then joined by heat welding through the welding substitute protrusions 60 and 61, the length of the deck portion 12 is increased. By changing the length W or the length L of the girder portion 30, pallets of different sizes can be easily manufactured, and in order to form pallets of different sizes, individual molding for each size is possible. As compared with the case where the molds are manufactured separately, the cost required for the molding mold can be reduced. For example, if five types of the length W of the deck portion 12 and three types of the length L of the girder portion 30 are prepared, 5 × 3 types of pallets can be manufactured with a total of 8 types of molds. On the other hand, in order to prepare individual dies for each size, 5 × 3 types of dies are required.

Further, when the length W of the deck portion 12 is changed, the molding die 50 is provided with a nesting rib lattice-shaped block die 51 and a nesting frame-shaped block die 52, and the required length is required. Cavities 55 are formed in the molding die 50 by selecting a nesting frame-shaped block die 52 having a size corresponding to the core ribs 53 by combining a number of nesting rib lattice block dies 51 corresponding to W. Therefore, it is only necessary to prepare a plurality of nesting rib lattice block molds 51 of the same size unit block, and a plurality of nesting frame block molds 52 of different sizes in block units. It is possible to form the deck portions 12 having different sizes W, and it is possible to reduce the cost of the molding die 50. The same effect can be obtained when changing the length L of the girder portion 30.

The strength of the deck portion 12 is changed by changing the interval between the lattice-shaped grooves 54 of the nested rib lattice-shaped block mold 51 to change the number of ribs of the rib lattice structure 20 or by changing the width of the grooves 54. And by changing the rib thickness of the rib lattice structure 20,
It can be easily adjusted. The strength of the girder portion 30 can be similarly adjusted.

Further, the arrangement interval of the deck sections 12 in the longitudinal direction of the girder section 30 (L direction in FIG. 1) is adjusted to adjust the deck section.
By changing the number of 12, the total area of the mounting surface 11 can be adjusted. For example, when enlarging the pallet 10, if the number of deck parts 12 is left as it is, there will be a space between the deck parts 12, but increasing the number of deck parts 12 will match the size of the pallet 10. It is possible to secure the total area of the loading surface 11 (the area where the loaded object can contact).

Further, the rib lattice structure 20 inside the deck portion 12
Compared with the rib 86 that is separately arranged in the vertical and horizontal directions of the second conventional example described above, the grid-like arrangement makes it easier to secure strength, the number of ribs can be reduced, and the overall weight of the pallet 10 is reduced. Can be converted. Furthermore, rib lattice structure
20 has a grid-shaped arrangement pattern and is substantially uniform over the entire surface of the deck portion 12.Therefore, in the case of the ribs 86 separately arranged in the vertical and horizontal directions of the pallet 80 of the second conventional example described above. In comparison, the length W of the deck portion 12 can be easily changed by the molding die 50 including the nesting rib lattice-shaped block die 51 and the nesting frame-shaped block die 52. The same effect is obtained when changing the length L of the girder portion 30.

The following experiment was conducted to confirm the effect of the present invention. The skid type according to the above-mentioned embodiment of the present invention (type in which the loading surface is formed only on the upper surface)
The performance of the pallet 10 (Experimental Example 1) and a conventional pallet (Comparative Example 1) having the same shape and dimensions as those of the conventional pallet (comparative example 1) in which the deck portion does not have a laminated plate structure was compared by a bending strength test based on JISZ0602. Which is a double-sided type pallet (type in which the work surface is formed on the upper surface and the lower surface) having the same main dimensions as those of the pallet 10 (Experimental Example 2) and the same shape and the same dimensions. The performance of a conventional pallet (comparative example 2) in which the deck portion does not have a laminated plate structure was also compared.

The size of each pallet is such that the size of the loading surface is 10
00mm (W direction) x 1000mm (L direction), the thickness of the deck is
30mm, girder height is 40mm, girder width is 100mm. In addition, the lattice pitch (rib spacing) of Experimental Example 1 and Experimental Example 2 according to the present invention is 50 mm, and Comparative Example 1 and Comparative Example 2 are 25 mm. In the experiment, a load was loaded on each pallet, and the deformation amount and the principal stress in the longitudinal direction (W direction) of the deck portion or the longitudinal direction (L direction) of the girder portion of each pallet at this time were measured. The weight of each pallet was also measured. The results are shown in Table 1.

[0031]

[Table 1]

According to Table 1, in the skid type, the deformation amount and the main stress in the longitudinal direction (W direction) of the deck portion are smaller in Experimental Example 1 than in Comparative Example 1, and the weight of the pallet is also Experimental Example 1. Is lighter, and the effect of the present invention is remarkable. In the double-sided type, the balance between the deformation amount and the main stress in the longitudinal direction of the deck portion (W direction) and the longitudinal direction of the girder portion (L direction) is better in Experimental Example 2 than in Comparative Example 2, and it is desired to secure strength. The values of the amount of deformation and the principal stress in the longitudinal direction of the deck portion (W direction) are also improved in Experimental Example 2 as compared with Comparative Example 2. In addition, the weight of the pallet is also in Comparative Example 2
The experimental example 2 is lighter than the experimental example 2, and the effect of the present invention is remarkable.

The present invention is not limited to the above-described embodiments, but includes other configurations capable of achieving the object of the present invention, and the following modifications and the like are also included in the present invention. That is, in the above embodiment, the deck section 12
The upper deck portion 13 and the lower deck portion 14, which are flat-bottomed bottomed cylindrical bodies having the rib lattice structure 20 inside, are formed on the respective open surfaces.
It is constructed by joining two laminated plates with 15, 15 but the deck part 12 does not need to be formed by joining flat-bottomed bottomed cylinders, it is not two but three. The opening faces 1 may be formed by joining the above laminated plates.
It is not necessary that the ribs 5 and 16 are joined to each other, and the rib rib structure 20 inside may be divided in any desired manner.In short, the upper plate-like portion 17 that forms the mounting surface 11 after joining and the back surface of the deck portion 12 are The lower plate-like portion 18 to be formed may be connected via the rib lattice structure 20.

For example, the deck portions 70 to 77 as shown in FIGS. 7A to 7H are also included in the present invention. The deck parts 70, 71, 72, 73 are provided with components that consist of only plate-shaped parts or components that do not have a rib lattice structure, and it is possible to simplify the molding of some of the components. 74,
75, 76 can be made to have a higher strength by using the same components as those of the upper deck portion 13 and the lower deck portion 14 to form a multi-ply laminated plate, and the deck portions 72, 73, 77 can be secured.
Can easily be positioned during bonding.

Further, in the above embodiment, the pallet 10 is constructed by assembling the three deck portions 12 and the three girder portions 30, but the number of these is arbitrary, for example, the deck portion 12
May be other plural or single,
The girder portion 30 may have any arrangement and number as long as the insertion portion 40 for inserting the arm of the forklift or the like can be formed therebetween.

Further, the deck portion 12 is formed by joining the upper deck portion 13 and the lower deck portion 14 by heat welding, but the joining method is arbitrary, and for example, an adhesive material, bolts or the like may be used. May be joined together. And the deck part 12 and girder part
The joining with 30 is performed by heat welding, but the joining method is not limited to this, and for example, an adhesive, a bolt or the like may be used for joining.

In addition, the number of ribs in each of the vertical and horizontal directions of the rib lattice structure 20 inside the upper deck portion 13, the lower deck portion 14, and the girder portion 30, the rib thickness, and the rib interval are arbitrary, and in order to obtain the necessary strength. I wish I could. Further, in the above embodiment, the upper deck portion 13, the lower deck portion 14 and the girder portion 30.
Each rib lattice structure 20 inside is formed with an orderly lattice of vertical and horizontal right angles, but may have any arrangement and shape, for example, a lattice intersecting at an angle may be used, and annular arrangement ribs and radials may be formed. A lattice in which the arrangement ribs intersect may be used. Furthermore, the thickness of the bottom portion or the bottom portion (upper plate-shaped portion 17, lower plate-shaped portion 18, etc.) of the bottomed tubular body forming the outer shapes of the upper deck portion 13, the lower deck portion 14, and the girder portion 30 is also arbitrary. In short, it suffices if the required strength can be obtained. And
The arrangement, shape, size, etc. of the nesting rib grid block mold 51 and the nesting frame block mold 52 correspond to the shape and the like of the rib grid structure 20 or the thickness of the cylinder part or bottom part of the bottomed cylinder. It may be arbitrary by, for example, the number of grooves 54 of the nesting rib lattice block mold 51, the width of the grooves 54, the grooves 54.
, The arrangement interval and arrangement form of the nested rib lattice block molds 51, the interval between the nested rib lattice block molds 51 and the nested frame block molds 52, and the like may be arbitrary.

The nesting rib lattice block mold 51 and the nesting frame block mold 52 of the molding die 50 are either movable plate side fixed plate or fixed plate side mold plate of the molding die 50, respectively. They may be installed on the side, and there is no positional restriction on the top, bottom, left, and right in these installations. Further, a plurality of nesting frame-shaped block molds 52 having different sizes in block units are prepared, but as a nesting frame-shaped block mold 78 of variable length in an assembly type as shown in FIG. Good.
Further, in the above embodiment, the upper deck portion 13 and the lower deck portion 14 are formed by the molding die 50 including the nesting rib lattice block mold 51 and the nesting frame block mold 52, and the girder part.
Although 30 is also formed by a molding die having a similar insert, these may be formed by an ordinary fixed die whose size cannot be changed. Alternatively, in forming either the upper deck portion 13, the lower deck portion 14 or the girder portion 30, the nesting rib lattice block mold 51 and the nesting frame block mold 52 are formed.
You may use the molding die provided with such a nest.

In the above embodiment, the upper deck portion 13,
The lower deck portion 14 and the girder portion 30 are formed by injection molding, but other molding methods such as press molding may be used as long as they can be molded into a predetermined shape. Further, in the above-mentioned embodiment, the material of the pallet 10 is polypropylene (PP), but it may be other synthetic resin such as high density polyethylene (HDPE), which is a lightweight and durable synthetic resin. Is desirable.

Further, although the pallet 10 of the above embodiment is a skid type in which the loading surface is formed only on the upper surface side,
The present invention may be applied to a double-sided pallet in which a loading surface is formed on both upper and lower surfaces such that the deck portion 12 is also provided under the girder portion 30. Further, the present invention is most suitable for the two-way fork type as in the above embodiment, but may be applied to the four-way fork type.

The overall size and shape of the pallet 10 of the present invention is arbitrary, and the upper deck portion 13 and the lower deck portion are
The size and shape of each part of 14 and the girder portion 30 are not limited to the size and shape of the above embodiment.

[0042]

As described above, according to the present invention, the deck portion of the pallet includes the upper plate-like portion forming the loading surface,
Since the lower plate-shaped portion forming the back surface of the deck portion and the rib lattice structure connecting the upper plate-shaped portion and the lower plate-shaped portion are formed in a laminated plate shape, the pallet is lightweight and highly rigid. In addition to being able to do it, since this deck part and girder part are assembled together to form a pallet,
The size of the pallet can be easily changed, and the pallet manufacturing cost can be reduced by manufacturing the pallet using a molding die whose size and the like can be changed. There is an effect.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a main part of the embodiment.

FIG. 3 is an exploded cross-sectional view showing a main part of the embodiment.

FIG. 4 is an exploded view showing another main part of the embodiment.

FIG. 5 is an exploded perspective view showing a part of a molding die used for manufacturing the pallet of the embodiment.

FIG. 6 is a cross-sectional view of a state where a part of the molding dies is combined.

FIG. 7 is a schematic cross-sectional view showing a modified example of the present invention.

FIG. 8 is a schematic perspective view showing another modification of the present invention.

FIG. 9 is a perspective view showing a first conventional example.

FIG. 10 is an explanatory view showing a second conventional example.

[Explanation of symbols]

10 Pallet 11 Loading surface 12, 70 to 77 Deck part 13 Upper deck part that is a bottomed cylinder 14 Lower deck part that is a bottomed cylinder 15,16,31 Opening surface 17 Upper plate-shaped part 18 Lower plate-shaped Part 20 Rib lattice structure 30 Girder part 50 Mold for molding 51 Nesting rib grid block mold which is a unit block forming the core member 52,78 Nesting frame block mold which is a cavity member

Claims (4)

[Claims] 1. A deck portion having a loading surface formed on an upper surface,
A synthetic resin pallet comprising a girder portion provided on the back side of the deck portion, wherein the deck portion is an upper plate-shaped portion that forms the object surface described above,
A lower plate-shaped portion that is provided substantially parallel to the upper plate-shaped portion and forms the back surface of the deck portion, and a rib lattice structure in which ribs that connect the upper plate-shaped portion and the lower plate-shaped portion are crossed with each other. A pallet made of synthetic resin, characterized in that a large number of closed spaces are formed by each lattice of this rib lattice structure and the upper plate-shaped portion and the lower plate-shaped portion. 2. The synthetic resin pallet according to claim 1, wherein the deck portion is formed by joining two flat bottomed cylindrical bodies each having a rib lattice structure inside, and joining their opening surfaces. The girder portion is a separate body from the two bottomed cylindrical bodies and has a flat bottomed cylindrical body having a rib lattice structure inside, and is joined to the back surface of the deck portion with its opening surface facing downward. A synthetic resin pallet characterized by being formed by. 3. A deck portion having a loading surface formed on the upper surface,
A method of manufacturing a synthetic resin pallet comprising a girder portion provided on the back side of the deck portion, wherein the deck portion is formed into two flat bottomed cylindrical bodies each having a rib lattice structure inside. After split molding with a mold for
These opening surfaces are joined together by heat welding through a predetermined welding margin, and the girder portion is separate from the two bottomed cylindrical bodies and has a rib lattice structure inside. A pallet made of synthetic resin, which is molded into a flat bottomed cylindrical body by a molding die, and is joined to the back surface of the deck portion by heat welding through a predetermined welding margin with its opening surface facing downward. Manufacturing method. 4. A mold for molding a synthetic resin pallet used in the method for manufacturing a synthetic resin pallet according to claim 3, comprising a core member formed by combining an arbitrary number of unit blocks. And a cavity member corresponding to the core member, for molding a synthetic resin pallet.