JPH0513937U - Pallets made of thermoplastic resin foam - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a pallet made of a thermoplastic resin foam-molded product, in which a fork insertion port is reinforced and which is easy to manufacture. A thermoplastic resin foam pallet 1 having a fork insertion opening 2 for inserting a fork such as a forklift has a solid portion 3 having a solid upper surface of the fork insertion opening 2. The solid portion was formed to have a thickness of 0.5 mm or more.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 TECHNICAL FIELD The present invention relates to a pallet made of a thermoplastic resin foam having a fork insertion port for receiving a load, which is used for carrying loads and the like.

[0002]

[Prior Art]

 Conventionally, pallets have been used as a platform for transporting objects by forklifts and the like. Among them, the thermoplastic resin foam pallet is lighter in weight and has better workability than a wooden pallet, and it is a good product with no hygiene problems. In the foam pallet, there is known a pallet provided with an insertion opening for inserting a fork (claw) of the forklift when the forklift is used (for example, Japanese Patent Publication No. 58-171343). ing. However, if the pallet is provided with a fork insertion port, the insertion port will be thinner than the other parts, and the deflection around the fork insertion port will increase. If the deflection of this pallet becomes large, there is a problem that the load loaded during the movement may lose the balance and cause the load to collapse. In addition, when a person walks on the fork insertion opening or when the tip of the fork contacts the top surface of the insertion opening, it is still thin and lacks strength, which may cause cracking, which may result in long-term failure. Was insufficient in terms of durability when used. Therefore, in order to solve the above problem, there is known a pallet in which a reinforcing core material made of metal or the like is provided inside the fork insertion port, but this pallet is used as a reinforcing core material during repeated use. There is a drawback in that the core part is slackened due to vibration, shock, load, etc., and the core material comes off from the fork insertion port of the pallet body. In order to solve such a problem, the applicant of the present invention has found that a pallet having a fork insertion hole obtained by in-mold molding of foam beads of a polyolefin-based synthetic resin has a cross-sectional shape that is different from the vertical, left-right, and difficult-moving shapes. Has proposed a pallet having a reinforcing core material therein (Japanese Patent Application No. 62-135291).

[0003]

[Problems to be solved by the device]

 However, the above pallet, which has a reinforcing core material with a cross-sectional shape consisting of vertical, horizontal, and difficult movements, has excellent reinforcing effects and excellent physical properties with no slack for long-term use. It was complicated and difficult to install. The present invention is intended to provide a pallet that solves the above-mentioned drawbacks of the prior art, and an object thereof is to provide a pallet made of a thermoplastic resin foam in which the fork insertion opening is reinforced and which is easy to manufacture. There is.

[0004]

[Means for Solving the Problems]

 The thermoplastic resin foam pallet of the present invention is a thermoplastic resin foam pallet provided with a fork insertion opening for inserting a fork such as a forklift, and at least a part of the upper surface of the fork insertion opening is It has a solid part which is made solid and the thickness of the solid part is 0.5 mm or more.

[0005]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of the present invention, FIG. 1 is an external perspective view showing an example of a thermoplastic resin foam pallet of the present invention, and FIG. 2 is a vertical section taken along the line II--II in FIG. It is sectional drawing which shows a surface. As shown in FIG. 1 and FIG. 2, the thermoplastic resin foam pallet 1 of the present invention is a thermoplastic resin foam pallet having a fork insertion opening 2 for inserting a fork such as a forklift. The fork insertion opening 2 is reinforced by providing a solid portion 3 in which the upper surface of the fork insertion opening 2 is solidified. In the pallet of the present invention, at least a part of the upper surface of the fork insertion port needs to be solid, and not only a part of the upper surface, but the entire upper surface, lower surface, side surface, etc. may be solid.

Since the solid portion obtained by melting and compressing the thermoplastic resin foam to make it solid is strong and has high strength, it reinforces the thin portion of the upper surface of the fork insertion port, and further contact with a fork or the like. The insertion opening can be protected from In addition, when compared with a sheet in which the sheets are simply stuck together, a solid sheet is superior in terms of adhesive strength between the solid portion and the pallet body. The solid part is mainly formed for reinforcement, and the thicker it is, the stronger the reinforcement effect can be expected. However, there is a limit to the sheet bonding, and the thicker the sheet or the more complicated the mold shape, the more difficult the bonding becomes, but the present invention does not have such a problem. On the other hand, sheet bonding by insert molding may be considered, but it is still possible to consider technical and facility problems such as the sheet clamping method. When the thickness of the solid part 3 of the pallet of the present invention is less than 0.5 mm, the strength against compression, impact, etc. is insufficient and the reinforcing effect cannot be obtained. Moreover, the thickness of the solid portion 3 is usually 0. It is preferably formed to have a thickness of about 5 to 5 mm. As the thickness of the solid portion increases, the strength increases, but the thickness of the solid portion 3 is limited by the thickness of the entire pallet and the size of the fork insertion hole. Generally, when the thickness of the double-sided pallet is about 170 mm and the height of the fork insertion hole is about 90 mm, it is preferable that the thickness of the solid portion 3 is about 2 mm.

FIG. 3 is a cross-sectional view of an essential part showing an example of a process for manufacturing the pallet of the present invention. Appropriate means may be used as a means for solidifying the fork insertion port. However, as shown in FIG. 3 (a), it is attempted to solidify the heating body 4 such as a heated iron plate with the thermoplastic resin foam plate 5. By contacting with the surface layer of the portion to be pressed and pressing at substantially the same speed as the melting rate, the periphery of the contact portion of the heating element 4 is solidified to form a solid portion 3 as shown in FIG. The thermoplastic resin foam plate 5 thus solidified is joined as a pallet upper surface portion 6 to a corresponding pallet lower surface portion 7 formed separately as shown in FIG. 2C to integrally form the present invention. You can get a pallet. Also, when solidifying, the pallet is not only integrated by forming the upper and lower pallets separately and solidifying as described above, but the pallet with the fork insertion port 2 is also integrated by foam molding. It is also possible to form the solid portion 3 by forming it in advance, inserting a heater having a shape such as a fork from the fork insertion port 2 and heating and pressing. The heating element 4 is made of a material having good heat conductivity such as iron or aluminum.

FIG. 4 shows another example of the thermoplastic resin foam pallet 1 of the present invention, and is a cross-sectional view of a main part showing a vertical cross-section of a part of the fork insertion port. In the pallet 1 of the present invention, solidification may be performed uniformly over the entire surface of a predetermined portion (upper surface, side surface, lower surface, etc.), but as shown in FIG. 4, the non-solid portion 8 remains as a convex portion. Alternatively, the solid portion 3 may be partially formed, and the surface of a predetermined portion may be formed into an uneven shape including a concave portion of the solid portion 3 and a convex portion of the non-solid portion 8. Generally, when the thermoplastic resin foam is solidified, the surface becomes slippery although the strength, hardness, etc. are improved. However, the surface is formed in the concavo-convex shape composed of the solid part 3 and the non-solid part 8 in this way. In this case, as compared with the case where the solid portion is provided over the entire surface, the non-solid portion 8 comes into contact with the fork, so that there is an effect that the fork becomes difficult to slip due to the frictional resistance of the foam. Also, although not particularly shown, in order to prevent the forks from slipping, the surface of the portion (predetermined portion) to be solidified is made solid by using a heating body having an uneven surface, and both the concave portion and the convex portion are solid. It is also possible to provide a solidified uneven solid portion at a predetermined position.

The material of the thermoplastic resin foam molded body pallet 1 may be any material that can be solidified. Among them, polyolefin resin foams are preferable from the viewpoint of ease of processing, price and physical properties (particularly toughness). For example, the base resin of polyolefin foam beads is polypropylene, polybutene, high density polyethylene, medium density. Polyethylene, linear low-density polyethylene, low-density polyethylene, linear ultra-low density polyethylene, propylene-butene random copolymer, propylene-ethylene random copolymer, propylene-ethylene block copolymer, etc. Examples thereof include a single resin or a mixture of two or more kinds, or a mixture containing these as a main component and a small amount of other components. Further, these resins may be crosslinked. A foaming ratio of the polyolefin resin foam is usually 3 to 50 times, and more preferably 5 to 30 times.

The fork insertion opening 2 of the pallet of the present invention is not particularly limited as long as a fork can be inserted, and may have any shape. For example, as shown in FIG. 1, it is common that two pallets 1 are provided in pairs from opposite sides of the pallet 1, but other than that, although not particularly shown, from all sides of the pallet. It may be provided or the like. Further, its size can be appropriately selected. The thermoplastic resin foam pallet of the present invention is optimally used in fields where hygiene is important, such as pallets used in clean rooms, and in fields where lightweight is important, such as air cargo pallets. be able to.

Next, the present invention will be described in more detail with reference to specific examples. Example 1 As shown in FIG. 1, a pallet having two fork insertion holes having a thickness of 170 mm, a width of 1100 × 1100 mm, and an insertion port height of 70 mm (the upper and lower wall thicknesses of the insertion port portion are 50 mm), A pallet made of a propylene-ethylene random copolymer resin foam was obtained in which the entire upper surface of the fork insertion opening was solidified to a solid thickness of 1.0 mm and reinforced. A fork tip compression test was performed on the obtained pallets. The results are shown in Table 1. Example 2 A pallet was formed in the same manner as in Example 1 except that the solid portion of Example 1 was partially solidified (a non-solid portion was provided and surface irregularities were formed as shown in FIG. 4), and the tip of the fork was compressed. The test was conducted. The results are shown in Table 1. Example 3 A pallet was formed in the same manner as in Example 1 except that the solid layer of Example 1 was formed thick (2.0 mm), and a fork tip compression test was performed. The results are shown in Table 1. Example 4 A pallet was formed and a fork tip compression test was performed in the same manner as in Example 1 except that the solid portion of Example 1 was increased (upper surface + side surface). The results are shown in Table 1.

Comparative Example 1 A pallet was formed in the same manner as the pallet of Example 1 except that the solid portion was not provided, and a fork tip compression test was conducted. The results are shown in Table 1. Comparative Example 2 A pallet was formed in the same manner as the pallet of Example 1 except that the thickness of the solid portion was made thinner (0.4 mm) than the pallet of Example 1, and a fork tip compression test was performed. The results are shown in Table 1.

For the fork tip compression test, the test device shown in FIG. 5 [Autograph AG500B (Shimadzu Corporation)] was used, and the fork tip jig 12 connected to the load cell 11 was used for loads of 250 kgf and 500 kgf. The state of the cut sample 13 when the cut sample 13 at the fork insertion port portion of the pallets of Examples and Comparative Examples was compressed under the condition of the descending speed of 20 mm / min was evaluated. The cut sample 13 having a solid part has a solid part as an upper surface, and a test is conducted by pressing the upper surface with a fork tip jig. Moreover, even if there is no solid part, a surface corresponding to the solid surface is an upper surface. A similar test was conducted. The test result was evaluated in three stages as follows. ○: The fork remains, but it is hardly noticeable. △: Fork marks are conspicuous but cracks do not occur. ×: Both fork marks and cracks occur.

[0014]

[Table 1]

[0015]

[Effect of the device]

 As explained above, the thermoplastic resin pallet of the present invention has a solid portion with a thickness of 0.5 mm or more in which at least a part of the upper surface of the fork insertion port is solidified. The solid part reinforces the thinned fork insertion part, which improves the strength of the entire pallet and reduces the deflection compared to the conventional non-reinforced pallet, and the pallet surface above the fork insertion port. There is no risk of cracking, and the effect is that a thermoplastic resin foam pallet having good workability and durability can be obtained. Even when compared to a pallet that uses a separate reinforcing material, it does not use a separate reinforcing material while having the same sufficient reinforcing effect, so the reinforcing material may fall off during use. It is possible to maintain stable performance without fear. Furthermore, since solidification may be performed by hot pressing with a heated heating body, the production is easier than, for example, the work of sticking a solid layer provided separately, and a thick solid layer can be easily obtained. In addition, since the separate reinforcing material is not used, the pallet does not become heavy, and the lightweight property, which is a major feature of the synthetic resin foam pallet, is not impaired. Further, when the tip of the fork comes into contact with the inside of the fork insertion port, the solidified portion has a high hardness, and therefore has a reinforcing effect of preventing damage to the fork insertion port of the pallet due to contact with the fork.

[Brief description of drawings]

FIG. 1 is an external perspective view showing an example of a pallet made of a thermoplastic resin foam of the present invention.

FIG. 2 is a sectional view showing a vertical section taken along line II-II in FIG.

FIG. 3 is a cross-sectional view of an essential part for explaining one example of a manufacturing process of a pallet made of a thermoplastic resin foam of the present invention.

FIG. 4 is a cross-sectional view of an essential part showing another example of the thermoplastic resin foam pallet of the present invention and showing a vertical cross section of a part of the fork insertion port.

FIG. 5 is an explanatory diagram showing a fork tip compression test method.

[Explanation of symbols]

 1 Thermoplastic foam pallet 2 Fork insertion slot 3 Solid part

Claims (1)

[Scope of utility model registration request] 1. A thermoplastic resin foam pallet provided with a fork insertion opening for inserting a fork such as a forklift, wherein at least a part of an upper surface of the fork insertion opening is solidified. A pallet made of a thermoplastic resin foam, wherein the solid portion has a thickness of 0.5 mm or more.