JPH0272048A - Synthetic resin pallet - Google Patents

Abstract

PURPOSE:To obtain a synthetic resin pallet easily molded and having an excellent structural strength, by providing reinforcing plates which continue substantially to both upper and lower decks and also continue substantially to opposite wall plates to each other in the inside of a beam composed of surrounding wall plates and having a nearly right angled and hollow pillar structure. CONSTITUTION:Beams 3, 4, 5 are arranged each at both edges and in the middle of upper and lower deck boards 1, 2 respectively. In the inside of the beams 3, 4, 5 with hollow structure, reinforcing plates 6, 7 are provided, continuing to the upper and lower deck boards 1, 2. The reinforcing plate 6 provided in parallel with the direction of inserting fork has a structure dividing the width of the beam 3, 4, 5 into two. The reinforcing plate 7 provided in a cross against the direction of inserting fork has a structure dividing the length of the beam 3, 4, 5 into three. Many lower reinforced ribs 8, 9 than the beam 3, 4, 5 in height are arranged as a unit with the deck board 1. The thickness of the reinforced rib 9 is more than 1.5 times of the thickness of the reinforced rib 8 parallel to the direction for inserting fork.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a synthetic resin pallet, and more specifically to a pallet for a forklift used when transporting, moving, storing, and storing articles. The present invention relates to a synthetic resin pallet that has small deflection and that deforms little against the load even when stored for a long period of time in a rack that supports only both edges of the pallet in an automated warehouse or the like.

[Conventional technology]

Conventionally, pallets for forklifts have been made of wood, metal, or synthetic resin.

As is well known, a forklift pallet is usually made up of upper and lower deck boards joined by girders at both ends of the deck boards and in the middle, and the fork can be inserted into the space between the adjacent girders. It has a structure. Among these, synthetic resin pallets have a limited wall thickness due to the molding process, and recycled materials such as polyethylene and polypropylene are sometimes used as the synthetic resin to reduce costs, making it difficult to obtain sufficient strength. The bending strength of the deck board was inferior to that of wooden or metal pallets. Therefore, devices with metal pipes, nets, etc. embedded in the deck board or near the deck board (
For example, Japanese Utility Model Publication No. 1983-10729), deck boards and metal pipes or nets integrally insert-molded (for example, Japanese Patent Publication No. 57-30736, Japanese Utility Model Application Publication No. 57-162130, Kaisho 58-12513
0), and those in which the arrangement and thickness of reinforcing ribs provided integrally with the deck board are changed (for example, Japanese Utility Model Publication No. 58-9868, Japanese Utility Model Publication No. 59-175018) have been proposed. There is. In addition, the girders of synthetic resin pallets generally have a hollow structure, but in order to prevent the tips of the forks from colliding with the hollow girders and destroying the girder walls when inserting the forks, the hollow girder It has been proposed that a reinforcing piece is installed near the edge of the deck board inside the deck and extend in a direction parallel to the fork insertion direction and continue across the upper and lower deck boards (for example, Japanese Patent Publication No. 60-55374). .

In recent years, when loading and storing goods on forklift pallets, automated warehouses have come into widespread use, where the goods can be put in and out of storage by computer commands. Because a pallet loaded with goods is held by only supporting the parts, synthetic resin pallets are subject to significant deflection and deformation even when used within the permissible loading weight range of the pallet, making it difficult to remove the loaded pallet from the automated warehouse. When moving the rack, it is often detected by or comes into contact with various detection and sensing devices installed around the rack or in the moving mechanism, leading to malfunctions and poor operation. At present, there is a demand for improvement as this may cause load drift.

[Problems to be solved by the present invention]

Currently, various reinforcement methods such as those described above have been proposed to maintain the strength of synthetic resin pallets. Not only does the weight of the product increase, but additional steps are required to secure the pipes and nets using bolts and screws, and to cover exposed pipes and nets with synthetic resin. The cost will be high. In addition, with the method of insert molding metal pipes and nets integrally with the deck board,
Because the thermal expansion coefficients of synthetic resin and metal are significantly different, twisting may occur after molding, and cracks may occur in the synthetic resin due to changes in the usage environment such as temperature and humidity, or stress due to loading and unloading of goods, which may cause strength to deteriorate. There are drawbacks such as a decrease in the amount of water and even loss of the synthetic resin portion.

In addition, reinforcing methods that involve changing the arrangement of reinforcing ribs that are integrally provided with the deck board require complicated molding molds, resulting in high mold production costs, and the molded product also has a complicated shape, making molding difficult. However, there are problems such as insufficient filling in details and welding.

Furthermore, installing reinforcing pieces near the edge of the deck board inside the hollow girder is effective in preventing the tip of the fork from colliding with the girder wall plate and breaking it. It has no effect on deflection or deformation due to the load of the article.

The present invention eliminates the drawbacks of the previously proposed synthetic resin pallets as described above, does not require the use of metal pipes or nets, has an extremely simple structure, and can be made using various ordinary molding methods. The object of the present invention is to provide a synthetic resin pallet that can be easily molded, has extremely high structural strength, and is especially suitable for use in automated warehouses.

[Means to solve the problem]

As a result of intensive studies to solve the above-mentioned problems with synthetic resin pallets, the inventors of the present invention have created a structure in which reinforcing plates are provided inside the hollow girders that are substantially continuous across the upper and lower deck boards. Further, the reinforcing plates substantially connect the wall plates of the girders facing each other, and at least one reinforcing plate is provided so as to equally divide the internal length and width of each girder. Further, on the back surface of the deck board on which goods are loaded, a large number of reinforcing ribs having a height lower than the girders are provided integrally with the deck board, parallel to and orthogonal to the fork insertion direction, and at least one of the reinforcing ribs At the fork abutment part, the reinforcing ribs that connect the wall plates of adjacent girders that face each other in substantially parallel have a constant thickness, and the reinforcing ribs that are perpendicular to the reinforcing ribs that connect the wall plates are slightly thicker. It was discovered that the above object of the present invention could be achieved by doing so, and the present invention was accomplished.

That is, the present invention provides a synthetic resin pallet comprising upper and lower deck boards and girders connecting the deck boards, and at least one girder is disposed at each end edge portion and an intermediate portion of the deck board. The girder has a hollow structure in the form of a substantially right prism whose periphery is made of wall plates, and inside each girder of the hollow structure, wall plates that are continuous and facing each other across the upper and lower deck boards are connected. At least one reinforcing plate is provided so as to divide the length and width of each girder into equal parts, and at least one reinforcing plate is provided on the back side of the upper deck board which is the loading surface, in parallel and orthogonal to the fork insertion direction. A large number of reinforcing ribs having a height lower than the girder are integrally arranged with the deck board, and at least among the reinforcing ribs, the reinforcing ribs connecting the facing wall plates of adjacent girders at the fork contact portion have a constant thickness. A pallet made of synthetic resin is characterized in that the thickness is 1.5 to 6 times the thickness of the reinforcing ribs that are orthogonal to the reinforcing ribs that connect the wall boards, and furthermore, the pallet is made of synthetic resin and has a thickness of 1.5 to 6 times the thickness of the reinforcing ribs that are orthogonal to the reinforcing ribs that connect the wall boards. At least one wall plate and reinforcing plate are arranged in each middle part of the girder, and the height is lower than that of the girder wall plate and reinforcing plate so that the area divided by the wall plate and reinforcing plate inside the girder is divided into approximately equal parts. This invention relates to a synthetic resin pallet having a structure in which reinforcing ribs are integrally provided with a deck board.

The synthetic resins used for manufacturing the synthetic resin pallet of the present invention include polyolefin resins such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polystyrene, acrylonitrile-styrene copolymer, Styrenic resins such as acrylonitrile-butadiene-styrene copolymer, polyvinyl chloride polyvinylidene chloride, vinyl chloride resins such as vinyl chloride-vinyl acetate copolymer, nylon 6, nylon 66, nylon 6.10, nylon 11, nylon 12
Polyamide resins such as polyethylene terephthalate, etc.
Polyester resins such as polybutylene terephthalate,
Further examples include thermoplastic resins such as polycarbonate resins, and resins such as phenol resins, unsaturated polyester resins, and diallyl phthalate resins can also be used. Among these, polyolefin resins, particularly polyethylene and polypropylene, are preferably used.

These synthetic resins can be used as a mixture of the above synthetic resins, if necessary, and may also contain antioxidants, ultraviolet absorbers, heat stabilizers, antistatic agents, flame retardants,
Additives such as crosslinking agents, dyes, pigments, organic or inorganic fillers, etc. can also be added and used.

In addition, these synthetic resins may be used as they are or mixed with the above additives to form pallets, but they may be used as a mixture containing commonly used blowing agents such as volatile blowing agents or chemical blowing agents. It may also be used to form pallets. When a mixture containing this foaming agent is used, the molded pallet is a foam with a low expansion ratio, and the surface layer forms a non-foamed layer, so it is the best from the viewpoint of both lightweight and strength of the pallet. preferable.

As a method for molding the synthetic resin pallet according to the present invention, commonly used molding methods such as injection molding and cast molding can be applied. Preferably, a method is employed in which the molded member is formed by using a mold for forming a molded member that is parallel to the deck board from the center of the pallet girder, and then welded at the center of the separated girder. This method is advantageous in terms of mold cost and molding machine size because it is not necessary to provide a long stroke slide core for providing a fork insertion port in the mold.

Next, an example of a pallet according to the present invention will be explained with reference to the drawings.

FIG. 1 is a perspective view showing an example of the pallet of the present invention, FIG. 2 is a front view of the pallet in FIG. 1, FIG. 3 is a top view of the AA cross section in FIG. 2, and FIG. is a perspective view of FIG. 3, FIG. 5 is a partially enlarged cross-sectional view showing another aspect of the pallet of the present invention, FIG. 6 is a perspective view of another example of the pallet of the present invention, and FIG. is an enlarged cross-sectional view of Fig. 6, and Fig. 8 is an enlarged view of the cross section of Fig. 6.
Figure 3 shows a cross-sectional perspective view of the pallet in the figures.

In the figure, I and ■ are molded members, 1 and 2 are deck boards, 3.4 and 5 are girders, 3a, 3b, 4a.

4b, 5a and 5b are wall plates of the girder; 6.7 is a reinforcing plate provided within the girder; 8. 9. 9a and 10 indicate reinforcing ribs, respectively.

In the synthetic resin pallet according to the present invention shown in FIGS.
and 20, one at each end edge and at the middle. Inside the girders 3, 4.5 having a hollow structure, reinforcing plates 6 and 7 are provided that extend continuously across the upper and lower deck boards 1.2, and the reinforcing plate 5 is provided in parallel to the fork insertion direction. Digit 3. 4. 5 opposing facing wall plates 3b-3b, 4b-4b and 5b-5b
The structure is such that the width of each girder 3 and 4.5 is divided into three by connecting them. Similarly, a reinforcing plate 7 provided in a direction perpendicular to the fork insertion direction connects the opposing wall plates 3a, -3a, 4a-4a and 5a-5a of the girders 3, 4.5, and connects each of the girders 3. 4. It has a structure that divides the length of 5 into three equal parts. Furthermore, a large number of reinforcing ribs 8 and 9, which are lower in height than the girders 3 and 4.5, are integrally provided with the deck board 1 at the fork contact portion on the back side of the upper deck board 1 on the side where goods are loaded. The reinforcing ribs 9 provided in the direction orthogonal to the fork insertion direction are connected to the adjacent beams 3-4. and 4-5, the wall plates 3a-4a and 4a-5a facing each other in substantially parallel are connected, and the wall plates 3a to 4-5 are connected.
The thickness is constant between 4a and 4a-5a. Moreover, the thickness of the reinforcing rib 9 is at least 1.5 times the thickness of the reinforcing rib 8 parallel to the fork insertion direction. Further, among the reinforcing ribs 9 provided in the direction perpendicular to the fork insertion direction, the thickness of the reinforcing rib 9a provided at the fork insertion port is 1.65 times the thickness of the reinforcing rib 8 parallel to the fork insertion direction. It has doubled.

Further, in another embodiment shown in FIG. 5, the girders 3, 4, 5 and wall plates 3a, 3b, 4a, 4b have a hollow structure.

5a, 5b, reinforcing plates 6, 7 provided inside the girder and reinforcing ribs 8 provided on the back surface of the upper deck board 1
, 9.9a is similar to the above example, but with a hollow structure girder 3. 4. A plurality of reinforcing ribs 10 are integrally molded and disposed on the back surface of the upper deck board 1 so as to equally divide the area partitioned by the wall plate and the reinforcing plate inside the upper deck board 1.

In order to manufacture the synthetic resin pallet of the present invention, for example,
Girder 3. 4. Molding members I and ■ having a partial shape at the center of 5 are molded, and girder 3, 4.5 is formed.
and by welding the end faces of the reinforcing plates 6.7 to each other.

Molded members r and ■ are girders 3 and 4 welded to each other, respectively.
．． It is necessary that the end faces of 5 and reinforcing plate 6.7 have the same shape, and by making the molded parts Can be welded together.

The example shown in the drawing uses polyethylene and uses an injection molding machine to mold parts ① and ② of the same shape with low foaming.
Digit 3. 4. 5 and the end faces of reinforcing plates 6 and 7 are welded to form a product pallet.

Although a two-way pallet has been described above, the valentine of the present invention can of course also be a four-way pallet. Examples of four-way pallets are shown in FIGS. 6 to 8. 3.4.5 Girder with hollow structure also in the case of a four-sided pallet
are wall plates 3a, 3b, and 4a.

4b, 5a, 5b and the reinforcing plate 6.7 are divided into equal parts, and reinforcing ribs 8.9 are integrally provided on the back surface of the deck board 1, which is the loading surface for articles. be done. In this case, the reinforcing rib 9 is connected to the adjacent girder 3-4.3-
4.3-4; 4-5.4-5.4-5 and 3-3
．． 3-3; 4-4.4-4; 5-5. Opposing wall plates 3a-4a, 3a-4a in 5-5,
3a-4a; 4a-5a, 4a-5a4a
-5a and 3b-3b, 3b-3b ・4b-
4b4b-4b; 5b-5b and 5b-5b are connected, and the thickness is constant between these wall plates. Moreover, the thickness of the reinforcing rib 9 is approximately equal to the thickness of the substantially parallel wall plates 3a, 3b, 4a, 4b, 5a,
The thickness is twice that of the reinforcing rib 8 that does not connect the ribs 5b.

Further, among the thicknesses of the reinforcing ribs 9, it is preferable that the thickness of the reinforcing ribs 9a provided at the fork insertion port is also at least twice the thickness of the reinforcing ribs 8. It is also a preferable embodiment to arrange reinforcing ribs on the back surface of the upper deck board so as to equally divide the area separated by the girder wall plate and the reinforcing plate.

Further, in the synthetic resin pallet of the present invention, as with conventional pallets of the same type, rubber-like materials for preventing slipping can be appropriately provided on the article loading surface and the fork contact portion. Methods for providing such a rubber-like material include, for example, a method in which a groove for attaching a non-slip rubber-like material is provided on the loading surface of a deck board and a rubber-like material of a desired shape is fitted into the groove, or a method in which a rubber-like material of a desired shape is fitted into the groove for attaching the non-slip rubber-like material, or There is a method in which a through or non-through hole is bored at an appropriate position of the abutment part, usually at the intersection of reinforcing ribs, and a prescribed rubber-like material is inserted into the hole.

In addition, it is also possible to have a structure in which an opening is provided on the article loading surface. By providing such an opening, water can be drained well when washing the pallet.

In the synthetic resin pallet according to the present invention, the first to fourth
A bending strength test and a bending creep test were conducted on the pallet shown in the figure and the pallet having the structure shown in FIG. 5 to examine the amount of deflection.

The results are shown in the table in comparison with two commercially available synthetic resin pallets.

The measurement conditions were as follows.

Bending strength test standard: JIS Z 0602-1976
Test method: Bending strength test method for flat pallets Test load: l
, 500Kg Ambient temperature: 23±2℃ Pallet dimensions: 900mmX1100mm Bending creep test standard: JIS Z 0606-1982
Test method Niblastik flat pallet reference test Bending creep test Test load: 1 000 kg Ambient temperature: 30 ± 2°C Pallet dimensions: 900 mm x 1100 mm [Function and effect] The synthetic resin pallet of the present invention has a substantially right-angled shape with a wall plate surrounding it. By creating a structure in which a reinforcing plate is provided inside the girder, which has a columnar hollow structure, and is substantially continuous across the upper and lower deck boards, and substantially continues between the facing wall boards, the edge of the deck board is The hollow structure girder is strongly reinforced not only near the edges but also near the center. In addition, the reinforcing plates are arranged so as to divide the internal length and width of each girder into equal parts, so when the goods are placed on the loading surface of the pallet, the reinforcing plates and the wall This has the effect of distributing the load by applying the load evenly to the plates. Furthermore, on the back surface of the deck board, which serves as the loading surface, a large number of reinforcing ribs, which are lower in height than the girder, are provided integrally with the deck board, parallel to and orthogonal to the fork insertion direction, so that adjacent girder The thickness of the reinforcing ribs that connect the facing wall boards is constant, and the thickness is 1.5 to 6 times the thickness of the reinforcing ribs that are orthogonal to the reinforcing ribs that connect the wall boards, thereby increasing the width of the deck board. The strength in the direction is strengthened, and the strength is made uniform between the girders, so that no matter where the fork is inserted between the girders, it will not bend, deform, or cause load deviation.

In addition, the pallet according to the present invention does not embed metal pipes or nets or insert molding, so it is not only lightweight, but also easy to use for fixing pipes and netting or covering exposed parts. No extra processes are required and the cost is low, and it also prevents deformation and twisting caused by the difference in thermal expansion coefficients between metal and synthetic resin, changes in the usage environment, and cracks in the synthetic resin part that occur due to repeated loads due to cargo handling. There are no omissions. Furthermore, the pallet according to the present invention is free from the risk of bending and deformation even if it is stored for a long period of time in a state where only the edges of the pallet loaded with goods are supported for a long period of time, such as in a storage system such as an automated warehouse. There are few. Furthermore, the pallet according to the present invention has an extremely simple structure, and the molding die also has a simple structure, so that mold manufacturing costs are low and a good product can be easily obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of the pallet of the present invention, FIG. 2 is a front view of the pallet in FIG. 1, FIG. 3 is a top view of the AA cross section in FIG. 2, and FIG. is a perspective view of FIG. 3, FIG. 5 is a partially enlarged cross-sectional view showing another aspect of the pallet of the present invention, FIG. 6 is a perspective view of another example of the pallet of the present invention, and FIG. , respectively, show an enlarged partial cross-sectional view of FIG. 6, and FIG. 8 shows a cross-sectional perspective view of the pallet shown in FIG. 6. ■ Molded member, 2 deck board, 4 and 5 girders, 3b, 4a, 4b, 5a and 5b7 Reinforcement plate, 9.9a, and 10 Reinforcement rib girder wall plate J / /p Patent applicant Fudo Kagaku Kogyo Co., Ltd. Agent (9070) Patent attorney Sadafumi Kobori J 2 , :1 J 3 r”; J b 4 D ] 59

Claims (3)

[Claims] (1) A synthetic resin pallet consisting of upper and lower deck boards and girders connecting the deck boards,
At least one girder is arranged at each end edge portion and the middle portion of the deck board, and the girder has a hollow structure in the shape of a substantially right prism whose periphery is made of wall plates, and each girder of the hollow structure At least one reinforcing plate is provided inside the deck so as to divide the length and width of each girder into equal parts, and at least one reinforcing plate is provided to connect the wall plates that face each other continuously across the upper and lower deck boards, and to divide the length and width of each girder into equal parts. On the back side of the upper deck board, which is the loading surface, a large number of reinforcing ribs, which are lower in height than the girders, are integrally arranged with the deck board, parallel to and orthogonal to the fork insertion direction, and at least the forks of the reinforcing ribs are arranged. The reinforcing ribs that connect mutually facing wall plates of adjacent girders at the abutting portions have a constant thickness, and moreover, the thickness of the reinforcing ribs that are perpendicular to the reinforcing ribs that connect the wall plates is 1.
A synthetic resin pallet characterized by being 5 to 6 times larger. (2) At least one girder wall is placed at each end edge and middle part of the deck board, so that the girder wall is divided into approximately equal parts by wall plates and reinforcing plates inside the hollow structure of the girder. 2. The synthetic resin pallet according to claim 1, wherein the reinforcing ribs, which are lower in height than the plates and the reinforcing plates, are integrally provided with the deck board. (3) The synthetic resin pallet according to claim 1, wherein the synthetic resin constituting the synthetic resin pallet is a low-foam thermoplastic synthetic resin.