Three-dimensional structure coated with polyurea resin

Abstract

To simply and inexpensively provide a three-dimensional structure having high versatility, which is lightweight yet has desired strength and durability and can be appropriately adapted to various different specifications and shapes. [Solution] A three-dimensional structure 1A is composed of at least a mold member 10A made of a low-density material and a structural member 20A formed of a polyurethane resin that covers the surface of the mold member 10A. The mold member 10A is composed of a top plate mold member 11A and a leg mold member 12A, which are separate bodies, and are connected via their contact surfaces FA.

Description

[Technical field]

[0001] The present invention relates to a three-dimensional structure in which the surface of a mold member made of a low-density material is covered with a structural member made of a polyurea resin. More specifically, the present invention relates to a three-dimensional structure that is lightweight yet has a desired strength and can be adapted to various different specifications and shapes, and is suitable for loading pallets, indoor and outdoor furniture, etc. [Background technology]

[0002] Pallets for loading and unloading, which are used to place items on the pallets and move them to a specified location using a forklift, are often used to move heavy objects, and therefore require high strength and light weight to make such moving work easy and efficient. Furthermore, since they are used repeatedly both indoors and outdoors, they are required to be highly resistant to wear and tear, and to have excellent water and weather resistance. For this reason, pallets made of resin materials, which are excellent in terms of strength, weight, and durability, have traditionally been used.

[0003] Conventional resin pallets are generally formed by injecting resin into a predetermined mold, as in the pallet (10) disclosed in Patent Document 1. To obtain high strength, multiple reinforcing walls and the like are provided, and in the pallet (10) of Patent Document 1, multiple reinforcing parts (12, 13, 14, 15) are provided on the top plate (deck board 11), and the area surrounded by the reinforcing parts is configured as an inner lattice part (19) with large squares of a batten structure. Furthermore, multiple reinforcing walls (reinforcing ribs 24, 34) are provided on the legs (beams 20, 30). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2023-000806 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional resin pallets, such as the synthetic resin pallet (10) disclosed in Patent Document 1, are made of only injection-molded resin materials, so a relatively large thickness is required to obtain the desired strength, and many reinforcing walls must be provided. For this reason, conventional resin pallets are relatively heavy, and complex molds are required to form the many reinforcing walls, increasing manufacturing costs. Furthermore, in order to manufacture pallets with different specifications, such as different sizes and the presence or absence of a back panel, expensive molds must be prepared for each specification, which increases the increase in manufacturing costs even more significantly.

[0006] The present invention was created in consideration of the above problems, and its purpose is to provide a simple and inexpensive three-dimensional structure that is lightweight yet has the desired strength and durability, is highly versatile so that it can be appropriately adapted to a variety of different specifications and shapes, and is suitable for loading pallets, indoor and outdoor furniture, etc. [Means for solving the problem]

[0007] The three-dimensional structure (1A, 1B, 1C) of the present invention for solving the above problem is at least composed of a plurality of mold members (10A, 10B, 10C) formed from a low-density material and structural members (20A, 20B, 20C) formed from a polyurethane resin covering the surfaces of the mold members, the plurality of mold members being connected to each other via their abutment surfaces (FA, FB, FC), and the structural members being configured to cover the outer peripheral edges of the abutment surfaces and most or almost all of the surfaces of the mold members excluding the abutment surfaces.

[0008] In the three-dimensional structure, the low-density material may be polystyrene foam.

[0009] Furthermore, in the three-dimensional structure, a reinforcing mesh sheet may be joined to a part or most of the surface of at least one of the mold members excluding the contact surface.

[0010] In addition, in the above three-dimensional structure, each of the multiple mold members may have at least one recess (30a-30f) on a surface, and the structural member may have an engagement portion (40a-40f) formed by the polyurethane resin covering at least a portion of the wall surface defining the recess.

[0011] Furthermore, in the three-dimensional structure, the locking portion may be formed so that an area projected onto the contact surface is larger than an area projected onto a surface other than the contact surface.

[0012] In addition, in the three-dimensional structure, at least two of the recesses are connected at the abutment surface, and at least one of the at least two recesses (30b, 30d / 30e, 30f) connected at this abutment surface has an opening on a surface other than the abutment surface, thereby forming at least a portion of the engagement portion (40b, 40d / 40e, 40f) to intersect with the abutment surface.

[0013] Furthermore, in the above three-dimensional structure, at least one of the mold members may have a void (50) therein, the void being connected to at least one of the at least two recesses (30b, 30d) that are connected at the abutment surface (FB), and the area of ​​the void projected onto the abutment surface may be larger than the opening area of ​​the communicating recess at the abutment surface.

[0014] In addition, the three-dimensional structure may be a loading pallet or indoor or outdoor furniture.

[0015] For reference, the reference numerals in the drawings of the embodiments of the present invention described below are used in parentheses to refer to the above-mentioned components. Effect of the Invention

[0016] The three-dimensional structure according to the present invention provides the following effects. That is, in addition to the structural members made of polyurea resin, the mold members made of a lightweight low-density material contribute to strength. This allows the thickness of the structural members to be thinner than that of a conventional three-dimensional structure made only of resin structural members, and further allows the desired strength to be obtained without providing multiple reinforcing walls, etc., making it possible to provide a three-dimensional structure that is lightweight compared to conventional structures while maintaining high strength.

[0017] In addition, for example, by making the mold members forming the flat top plate and the approximately columnar legs (beams) separate, each mold member can be made to have a simple shape with almost no irregularities, and even if a molding die is required to manufacture the mold members, there is no need to provide the die with complex irregularities, etc., thereby reducing manufacturing costs. Furthermore, for example, by disassembling a three-dimensional structure using components of the same shape as the smallest structural unit, it becomes possible to provide three-dimensional structures of different sizes easily and inexpensively by simply preparing a single mold member for forming the structural unit. [Brief description of the drawings]

[0018] [Figure 1] 1 is a perspective view of a pallet according to a first embodiment of the present invention as viewed from diagonally above to the right; FIG. [Diagram 2] 1 is a perspective view of a pallet according to a first embodiment of the present invention as viewed from diagonally below on the left; FIG. [Diagram 3] 2 is a cross-sectional view taken along line P1-P1 in FIG. 1. [Figure 4] 1 is a perspective view of a top plate mold member provided on a pallet according to a first embodiment of the present invention, viewed from diagonally above to the right. FIG. [Diagram 5] 1 is a perspective view of a leg mold member provided on a pallet according to a first embodiment of the present invention, viewed from diagonally above to the right. FIG. [Figure 6] 1 is a perspective view of a molding member provided on a pallet according to a first embodiment of the present invention, viewed from diagonally below on the left; FIG. [Figure 7]1 is a perspective view of a mold member in which a reinforcing mesh sheet is joined to a top plate mold member, as viewed from diagonally above to the right. [Figure 8] 1 is a perspective view of a table according to a first embodiment of the present invention as viewed from diagonally above to the right; [Figure 9] 9 is a cross-sectional view taken along the line P1-P1 in FIG. 8. [Figure 10] 1 is a perspective view of a top plate mold member provided on a table according to a first embodiment of the present invention, viewed from diagonally above to the right. FIG. [Figure 11] 1 is a perspective view of a leg mold member provided on a table according to a first embodiment of the present invention, viewed from diagonally above to the right. FIG.

[0019] [Figure 12] 1 is a perspective view of a pallet according to a second embodiment of the present invention, viewed from diagonally above to the right. FIG. [Figure 13] FIG. 11 is a perspective view of a pallet according to a second embodiment of the present invention as viewed from diagonally below on the left. [Figure 14] 13 is a cross-sectional view taken along the line P2-P2 in FIG. 12. [Figure 15a] 11 is a perspective view of a top plate mold member provided on a pallet according to a second embodiment of the present invention, viewed from diagonally above to the right. FIG. [Figure 15b] 15b is a cross-sectional view taken along line P3-P3 in FIG. 15a. [Figure 16a] 11 is a perspective view of a leg mold member provided on a pallet according to a second embodiment of the present invention, viewed from diagonally above to the right. FIG. [Figure 16b] 16b is a cross-sectional view taken along line P4-P4 in FIG. 16a. [Figure 17a] 11 is a perspective view of a leg mold member provided on a pallet according to a second embodiment of the present invention, viewed from diagonally above to the right. FIG. [Figure 17b] 17b is a cross-sectional view taken along line P5-P5 in FIG. 17a. [Figure 18] 11 is a perspective view of a molding member provided on a pallet according to a second embodiment of the present invention, viewed from diagonally below on the left side. FIG. [Figure 19] 11 is a perspective view of a molding member provided on a pallet according to a second embodiment of the present invention, viewed from diagonally above to the right. FIG. [Figure 20] 20 is a cross-sectional view taken along the line P6-P6 in FIG. 19. [Figure 21] 11 is a perspective view of a table according to a second embodiment of the present invention as viewed from diagonally above to the right. FIG. [Figure 22] 22 is a cross-sectional view taken along the line P2-P2 in FIG. 21. [Figure 23a] 13 is a perspective view of a top plate mold member provided on a table according to a second embodiment of the present invention, viewed from diagonally above to the right. FIG. [Figure 23b] 23b is a cross-sectional view taken along line P3-P3 in FIG. 23a. [Figure 24a] 11 is a perspective view of a leg mold member provided on a table according to a second embodiment of the present invention, viewed from diagonally above to the right. FIG. [Figure 24b] 24b is a cross-sectional view taken along line P4-P4 in FIG. 24a. [Diagram 25] 13 is a perspective view of a mold member provided on a table according to a second embodiment of the present invention, viewed from diagonally above to the right. FIG. [Figure 26] 26 is a cross-sectional view taken along line P5-P5 in FIG. 25.

[0020] [Figure 27] FIG. 11 is a perspective view of a pallet according to a third embodiment of the present invention, viewed from diagonally above to the right. [Figure 28] FIG. 11 is a perspective view of a pallet according to a third embodiment of the present invention, viewed from diagonally below on the left. [Figure 29] 28 is a cross-sectional view taken along line P7-P7 in FIG. 27. [Figure 30a] 13 is a perspective view of a top plate mold member provided on a pallet according to a third embodiment of the present invention, viewed from diagonally above to the right. FIG. [Figure 30b] This is a cross-sectional view taken along line P8-P8 in Figure 30a. [Figure 31a]13 is a perspective view of a leg mold member provided on a pallet according to a third embodiment of the present invention, viewed from diagonally above to the right. FIG. [Figure 31b] This is a cross-sectional view taken along line P9-P9 in Figure 31a. [Diagram 32] 11 is a perspective view of a molding member provided on a pallet according to a third embodiment of the present invention, viewed from diagonally below on the left. FIG. [Diagram 33] 13 is a perspective view of a molding member provided on a pallet according to a third embodiment of the present invention, viewed from diagonally above to the right. FIG. [Diagram 34] 34 is a cross-sectional view taken along line P10-P10 in FIG. 33. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] A pallet and a table are selected as three-dimensional structures according to the present invention, and the first to third preferred embodiments thereof will be described below with reference to Figs. 1 to 34. Here, the front-rear, left-right, and up-down directions in the description are defined based on the coordinate axes in each drawing. Specifically, the +X direction is defined as the front direction, the -X direction as the rear direction, the +Y direction as the right direction, the -Y direction as the left direction, the +Z direction as the up direction, and the -Z direction as the down direction. In addition, the horizontal plane is defined as the XY plane, and the vertical planes are defined as the XZ plane and the YZ plane. Therefore, Figs. 1 and 8 show the configuration of the pallet 1A and the table 1A viewed from the upper right direction in the front. Note that each figure is a conceptual diagram, and therefore some of the configurations may be exaggerated. For this reason, the front-rear and left-right lengths and thicknesses of the top plate and legs (beams) of the pallet and the table, and the dimensions of each recess provided in the mold member may be shown at different scales.

[0022] In addition, in this specification, the term "approximately" is not limited to being strictly the same, but is a concept that includes errors and modifications that do not lose their identity. For example, "almost all" is not limited to being strictly all, but includes forms that can be regarded as the same as all from the perspective of action and effect.

[0023] In this specification, the description is based on a pallet for cargo handling with four-way claw insertion and one fixed loading surface, but the external shape and dimensions of the pallet of the present invention are not particularly limited as long as it can perform the specified function. An example of a standard size that is widely used as defined by the JIS standard is 1100 mm long x 1100 mm wide x 144 mm high.

[0024] In addition, although the present specification describes a table with four legs, the form and shape of the furniture of the present invention are not particularly limited as long as it can perform a predetermined function. Specific examples include furniture such as tables, chairs, desks, and cabinets, and furniture frames such as bed frames and sofa frames.

[0025] First Embodiment First, a pallet 1A and a table 1A according to a first embodiment of the present invention will be described with reference to Figures 1 to 11. This embodiment is the simplest form of the pallet and table according to the present invention.

[0026] <Pallet 1A Configuration> As shown in Fig. 1 and Fig. 2, the basic form of the pallet 1A is composed of a top plate 1A-1 having an upper surface 1A-1a on which an article is placed, and nine legs 1A-2 arranged in a lattice pattern on the lower surface 1A-1b of the top plate 1A-1. As shown in Fig. 3, the top plate 1A-1 and the nine legs 1A-2 are formed by covering the surfaces of the top plate mold member 11A and the leg mold member 12A, which are combined via abutment surfaces FA forming a horizontal plane, with a structural member 20A. More specifically, the top plate 1A-1 is formed by covering the entire surface of the top plate mold member 11A except for the abutment surfaces FA with the structural member 20A, and the legs 1A-2 are formed by covering the entire surface of the leg mold member 12A except for the abutment surfaces FA with the structural member 20A. The structural member 20A covers the entire surface of the mold member 10A, including the outer peripheral edge of the contact surface FA between the top mold member 11A and the leg mold member 12A. As a result, the pallet 1A has a structure in which the core is formed by the mold member 10A and the surface layer is formed by the structural member 20A.

[0027] In order to connect the top plate mold member 11A and the leg mold member 12A with the desired strength, the structural member 20A preferably covers a large part of the outer periphery of the abutment surface FA, and most preferably covers substantially the entire outer periphery. The large part of the outer periphery means 50% or more, preferably 75% or more of the length of the outer periphery. It is also preferable to cover a large part of the entire surface of the mold member 10A excluding the abutment surface FA, and most preferably covers substantially the entire surface. The large part of the entire surface of the mold member 10A means 50% or more, preferably 75% or more of the total surface area.

[0028] The top plate mold member 11A and the leg mold member 12A do not need to be fixed to each other just by being placed in contact with each other, but in consideration of the workability when spraying the polyurethane resin, a part of the contacting surface may be lightly fixed (temporarily fixed) with an adhesive, double-sided adhesive tape, etc. A recess and a protrusion may be provided on the contacting surface to fit each other.

[0029] As one example, the mold member 10A and the structural member 20A are configured so that when the pallet 1A is deformed by an external force, they come into close contact with each other without moving relative to each other at their contact surfaces (abutment surfaces FA). As another example, when the pallet 1A is deformed by an external force, they are configured so that they move relative to each other at their contact surfaces (abutment surfaces FA). The contact form between the mold member 10A and the structural member 20A will be described in detail in the next section on "Mold member 10A."

[0030] [Molding member 10A] The mold member 10A is a component that determines the basic form of the pallet 1A, and functions as a mold for forming the structural member 20A into the surface layer of the pallet 1A. The mold member 10A also functions as a structural member (core material) that resists external forces by having a predetermined mechanical strength and rigidity. As described above, the mold member 10A is composed of a top plate mold member 11A and nine leg mold members 12A that are configured as separate bodies, and the top plate mold member 11A and each leg mold member 12A are in contact with each other via abutment surfaces FA that are horizontal surfaces, as shown in FIG. 3.

[0031] [Top plate part 11A] As shown in FIG. 4, the top plate mold member 11A is formed as a flat plate member having a shape projected onto a horizontal plane (hereinafter referred to as a planar shape) that is approximately rectangular and has a predetermined thickness, for example, a thickness of 60 to 90 mm. The top plate mold member 11A is formed from a low-density material with a low specific gravity, for example, a low-density material having bubbles or voids inside. Specifically, it is formed from a foamed closed-cell resin material such as polystyrene foam or polyethylene foam, a resin or paper cardboard having a trust structure or honeycomb structure, or the like, and is manufactured by an existing method such as injection molding or extrusion molding. From the viewpoints of balance between mechanical strength and weight, surface paintability, manufacturing costs, and the like, polystyrene foam is most preferable. In this embodiment, it is manufactured by injection molding using hard polystyrene foam with an expansion ratio of 35.

[0032] The top plate mold member 11A has an upper surface 11Aa that forms the upper surface of the top plate 1A-1 via the structural member 20A, a lower surface 11Ab that faces the leg mold member 12A and forms the abutment surface FA, and four side surfaces 11Ac located on the front, rear, left and right sides, all of which are formed as flat surfaces. Here, the shape of the top plate mold member 11A is not limited to this shape, and may be a shape that appropriately includes elements suitable for the usage situation. For example, a plurality of holes may be provided through the top plate mold member 11Aa to drain water that accumulates on the top plate mold member 11Aa. In addition, anti-slip unevenness may be arranged on the top plate mold member 11Aa so that the article to be placed on it is stable, and / or a convex portion to prevent the article from falling off may be arranged on the periphery of the top plate mold member 11Aa. These elements may be integrated with the top plate mold member 11A, or may be configured as separate mold members. When they are configured as separate mold members, they may be connected in the same manner as the connection between the top plate mold member 11A and the leg mold member 12A described later, that is, by covering the outer periphery of the contact surface with the structural member 20A. The lower surface 11Ab forming the contact surface FA may be formed integrally with or with a recess or protrusion that serves to position the leg mold member 12A or an element that restricts the relative movement (sliding) with the leg mold member 12A.

[0033] [Leg mold member 12A] As shown in FIG. 5, the leg mold member 12A has a basic shape of a substantially inverted pyramid, and the top surface 12Aa, which faces the top plate mold member 11A and constitutes the contact surface FA, the bottom surface 12Ab, and the four side surfaces 12Ac located on the front, back, left and right are all formed by flat surfaces. The dimensions of the top surface 12Aa are, for example, 150 to 250 mm square x 60 to 90 mm high. However, the shape of the leg mold member 12A is not limited to this shape, and may be any shape that functions as a leg such as a rectangular parallelepiped or cylinder and can secure a nail insertion opening with a width of about 150 to 250 mm. In addition, the shape of the top surface 12Aa that forms the contact surface FA may be a shape in which a recess or protrusion that performs a positioning function with respect to the top plate mold member 11A or an element that restricts relative movement (sliding) with the top plate mold member 11A is integrally formed or added. The leg mold members 12A, like the top plate mold member 11A, are made of a low density material with a small specific gravity, specifically, a foamable resin material such as polystyrene foam, or a resin corrugated cardboard, and are manufactured by injection molding, etc. In this embodiment, they are manufactured by injection molding using hard polystyrene foam with an expansion ratio of 35.

[0034] The nine leg mold members 12A are arranged in a grid pattern in three rows at approximately equal intervals in the front-to-back and left-to-right directions, as shown in Fig. 6, with their upper surfaces 12Aa in contact with the lower surface 11Ab of the top plate mold member 11A. As described above, the lower surface 11Ab of the top plate mold member 11A and the upper surface 12Aa of the leg mold member 12A in this embodiment are both flat surfaces, and a horizontal contact surface FA is formed through these flat surfaces.

[0035] As described above, the mold member 10A also functions as a structural member. That is, when an external force is applied to the pallet 1A, for example, when an article is placed on it, the mold member 10A is deformed by the external force (bending moment) acting through the structural member 20A. The mold member 10A, which has predetermined mechanical properties and rigidity, functions as a structural member by generating bending stress as internal resistance against the external force (bending moment).

[0036] As shown in FIG. 7, a reinforcing mesh sheet MS may be bonded to the upper surface 11a of the top plate mold member 11A on which a heavy object is placed. It is preferable to bond it to most of the surface of the mold member on which the heavy object is placed, and more preferable to bond it to almost the entire surface. In addition to the upper surface 11a of the top plate mold member 11A, a reinforcing mesh sheet MS may be bonded in a lattice or strip shape to the surface of the lower surface 11b except for the contact surface FA with the leg mold member 12A. The larger the bonded area, the more mechanical strength such as bending strength is reinforced. It is set taking into consideration the use and manufacturing cost of the pallet. A part of the surface of the mold member means an area less than 50% of the surface area, and a majority means an area of ​​50% or more, preferably 75% or more.

[0037] As a joining method, for example, a mesh sheet MS is laid on the upper surface 11a of the top plate mold member 11A, and then polyurethane resin is sprayed from above to form the structural member 20A. Alternatively, polyurethane resin may be sprayed on the upper surface 11a of the top plate mold member 11A, and then a mesh sheet MS is laid, and polyurethane resin is further sprayed from above to form the structural member 20A. The laying of the mesh sheet and the spraying of the polyurethane resin may be repeated multiple times. In either case, the thickness of the structural member 20A formed from the polyurethane resin is preferably set to the range described below.

[0038] The form of the reinforcing mesh sheet may be woven fabric, knitted fabric, nonwoven fabric, or a lattice or honeycomb sheet. From the viewpoint of bending strength and tensile strength, woven fabric and honeycomb sheet are preferable. A composite material of a woven fabric made of fibers and a synthetic resin may also be used. Examples of the weave of the woven fabric include plain weave, twill weave, and satin weave. Either a general biaxial fabric or a multiaxial fabric may be used. The thickness and basis weight of the mesh sheet are not limited as long as the desired reinforcing effect is obtained. The thickness is in the range of 0.2 to 1.0 mm, and the basis weight is 200 to 800 g / m 2 A plurality of mesh sheets may be used in layers.

[0039] Examples of fibers constituting the woven fabric include high-strength fibers such as carbon fibers, glass fibers, boron fibers, ceramic fibers, basalt fibers, aramid fibers, polyparaphenylene benzobisoxazole (PBO) fibers, high-strength polyethylene fibers, wholly aromatic polyester fibers, etc. From the viewpoints of mechanical strength and production costs, carbon fibers, glass fibers, basalt fibers, and aramid fibers are preferred, and basalt fibers and aramid fibers are more preferred.

[0040] The porosity of the reinforcing mesh sheet is not limited as long as it is within a range that can obtain the desired reinforcing effect. When the reinforcing mesh sheet is coated with a polyurethane resin and bonded, a large porosity allows the polyurethane resin to easily penetrate and improves the bonding strength. It is set based on the balance between mechanical strength such as bending strength and bonding strength. A range of 50% to 95% is exemplified.

[0041] As described above, the contact form between the mold member 10A and the structural member 20A may be a form in which they do not move relative to each other when deformed by contacting in a tight contact state, or a form in which they move relative to each other when deformed by contacting in a non-tight contact state. Considering the distribution form of bending stress that increases in proportion to the distance from the neutral plane, the latter (contact form in which the contact surfaces move relative to each other) in which the mold member 10A and the structural member 20A deform independently with their respective neutral planes is more useful in increasing the strength of the pallet 1A than the former (contact form in which the contact surfaces do not move relative to each other) in which the mold member 10A and the structural member 20A deform integrally with one neutral plane. For this reason, an element that makes the contact between the mold member 10A and the structural member 20A non-tight may be interposed between them, such as disposing a lubricant or a release layer made of a lubricant on the contact surface of the mold member 10A with the structural member 20A.

[0042] [Structural member 20A] The structural member 20A is a functional element that provides the pallet 1A with a desired strength, and as described above, forms the surface layer of the pallet 1A by covering the entire surface of the mold member 10A, including the outer periphery of the abutment surface FA between the top plate mold member 11A and the leg mold member 12A. At this time, the structural member 20A connects the top plate mold member 11A and the leg mold member 12A, which are configured as separate bodies, with a predetermined bonding strength based on its own mechanical properties. In other words, the top plate mold member 11A and the leg mold member 12A are mechanically connected to each other through the structural member 20A that covers the outer periphery of the abutment surface FA, even if the structural member 20A or other structural members or adhesive members are not mechanically or chemically connected or bonded to each other by being interposed between the abutment surface FA. In this way, the structural member 20A also functions as an element that mechanically connects the top plate mold member 11A and the leg mold member 12A, which are configured as separate bodies.

[0043] The structural member 20A is formed from a polyurea resin having high tensile strength, flexibility, and high hardness. The polyurea resin is a resin compound mainly composed of urea bonds formed by a chemical reaction between an isocyanate component (main agent) and an amine component (hardener). The ratio of the two components constituting the polyurea resin, the weight average molecular weight, and the like are not limited as long as the desired mechanical properties (tensile strength, hardness, etc.) and a suitable pot life are obtained. In this embodiment, the structural member 20A is formed using Extreme HP11-50 manufactured by Rhino Linings, which provides excellent mechanical properties. It is desirable to determine the thickness of the structural member 20A in consideration of the excellent mechanical properties, curing speed, manufacturing cost, and the like of the polyurea resin. Specifically, the structural member 20A is formed on the surface of the mold member 10A so as to have a thickness of 1.0 to 4.0 mm, preferably 1.5 to 3.5 mm, and more preferably 2.0 to 3.0 mm. This makes it possible to provide a pallet 1A that is high in strength and rigidity, yet lightweight and excellent in productivity.

[0044] The method of forming the structural member 20A on the surface of the mold member 10A is preferably spray coating using a spray gun or the like, which is easy to control the thickness of the coating film and has excellent workability. The spraying device for spraying the polyurea resin onto the mold member can be an existing spraying device. The spraying device is a device that sprays the mist-like polyurea resin, which is generated by colliding and mixing a polyisocyanate component and an amine component at high temperature and causing a chemical reaction, onto the object to be coated. In this embodiment, the surface of the mold member 10A is relatively smooth, but when spraying onto a mold member having a recessed portion, which will be described later, the conditions such as the temperature at which the base agent and hardener of the spraying device are heated, the tank pressure from which the base agent and hardener are discharged, and the discharge amount and mixing ratio of the base agent and hardener are adjusted so that a polyurea layer of the desired thickness is formed on the inner wall surface. Multiple polyurea resins with different pot lives may be used. The method of forming the structural member 20A is not limited to spraying, and other existing methods may be used as appropriate. For example, dip coating, in which the mold member 10A is immersed in a mixed solution of two agents and then taken out to dry and harden to form the structural member 20A, or hand painting using a brush or roller brush may be used. These methods may also be combined.

[0045] Also, in order to improve the adhesion between the structural member 20A and the mold member 10A, a primer treatment may be applied to the surface of the mold member 10A. Furthermore, in order to improve the aesthetic appearance, a finishing layer may be provided on the surface of the structural member 20A. For the finishing layer, existing paints such as polyurethane-based, acrylic silicone-based, and fluorine-based paints may be used as appropriate, and pigments may be blended to achieve the desired color. A base layer may be provided under the finishing layer to improve color development.

[0046] <Effects of Palette 1A> The pallet 1A according to the present embodiment having the above-mentioned configuration provides the following effects. That is, the mold member 10A made of extremely lightweight polystyrene foam and the structural member 20A made of lightweight polyurethane resin formed so as to cover the mold member 10A function as structural members that resist the external force (bending moment) applied to the pallet 1A. Specifically, the mold member 10A and the structural member 20A each have a predetermined rigidity, so that the deformation (strain) caused by the external force (bending moment) is reduced, and the bending stress of the mold member 10A and the structural member 20A, which increases in proportion to the deformation, is suppressed. As a result, the thickness of the structural member 20A required to provide the same strength as that of a conventional pallet made only of polypropylene resin can be reduced, and the weight can be reduced. In addition, since deformation can be suppressed without providing multiple reinforcing walls to increase rigidity (reduce deformation), an expensive injection molding die is not required, and manufacturing costs can be reduced. Furthermore, even if it is necessary to provide a reinforcing wall in the structural member 20A to obtain higher strength, this can be easily and inexpensively achieved by simply forming a groove or the like for forming the reinforcing wall in the mold member 10A by, for example, machining. Due to the above effects, it is possible to easily and inexpensively manufacture and provide a pallet 1A that is lightweight and has the desired strength.

[0047] In addition, in the pallet 1A in which the mold member 10A is composed of the top plate mold member 11A, each surface of which is flat and of a simple shape, and the nine leg mold members 12A, each surface of which is similarly flat and of a simple shape and made of an approximately inverted quadrangular pyramid, and these mold members are constructed as separate bodies, even if the top plate mold member 11A and the leg mold members 12A are made by injection molding, the manufacturing cost of the injection mold used therefor is far lower than that of the complex injection mold used for conventional resin pallets. In this way, by constructing the mold member 10A from the separate top plate mold member 11A and leg mold members 12A, it becomes possible to manufacture and provide the pallet 1A, which is lightweight and has the desired strength, at low cost.

[0048] In addition, by combining the existing top plate mold member 11A and leg mold member 12A, it is possible to flexibly respond to requests for additions or changes to specifications, such as increasing the surface area for placing items and / or the number of legs (beams). Therefore, when constructing a pallet 1A with different specifications (shapes), it is no longer necessary to manufacture a different injection molding die for each specification, and it becomes possible to provide pallets 1A with different specifications (shapes) at low cost. In order to respond appropriately to the above requests, it is advisable to set the size and shape of the top plate mold member 11A so that the surface area can be adjusted for each top plate mold member 11A.

[0049] As shown in Fig. 8, the table 1A is a table in its basic form, which is composed of a top plate 1A-1 having an upper surface 1A-1a on which an article is placed, and four legs 1A-2 arranged at the four corners of a lower surface 1A-1b of the top plate 1A-1. As shown in Fig. 9, the top plate 1A-1 and the four legs 1A-2 are formed by covering the surfaces of a top plate mold member 11A and a leg mold member 12A, which are combined via a horizontal abutment surface FA to form a mold member 10A, with a structural member 20A. More specifically, the top plate 1A-1 is formed by covering the entire surface of the top plate mold member 11A except for the abutment surface FA with the structural member 20A, and the legs 1A-2 are formed by covering the entire surface of the leg mold member 12A except for the abutment surface FA with the structural member 20A. The structural member 20A covers the entire surface of the mold member 10A, including the outer peripheral edge of the contact surface FA between the top mold member 11A and the leg mold member 12A. As a result, the table 1A has a structure in which the core is formed by the mold member 10A and the surface layer is formed by the structural member 20A.

[0050] As with the pallet 1A described above, the structural member 20A most preferably covers almost the entire outer periphery of the contact surface FA in order to connect the top plate mold member 11A and the leg mold member 12A with the desired strength, and most preferably covers almost the entire surface of the mold member 10A except for the contact surface FA. The top plate mold member 11A and the leg mold member 12A may be lightly fixed (temporarily fixed), or may have recesses and protrusions on the contact surfaces to fit together. The contact form between the mold member 10A and the structural member 20A may be a form in which they contact in a tight contact state so that they do not move relative to each other when deformed, or a form in which they contact in a loose contact state so that they move relative to each other when deformed.

[0051] [Molding member 10A] The mold member 10A is a component that determines the basic form of the table 1A, and functions as a mold for forming the structural member 20A as the surface layer of the table 1A. The mold member 10A also functions as a structural member (core material) that resists external forces by having a predetermined mechanical strength and rigidity. As described above, the mold member 10A is composed of a top plate mold member 11A and four leg mold members 12A that are configured as separate bodies, and the top plate mold member 11A and each leg mold member 12A are in contact with each other via abutment surfaces FA that are horizontal surfaces, as shown in FIG. 9.

[0052] As shown in Fig. 10, the top plate mold member 11A is formed as a flat plate member having a substantially rectangular shape when projected onto a horizontal plane (hereinafter referred to as the planar shape) and a predetermined thickness, for example, 1 cm to several cm. As with the above-mentioned pallet 1A, the top plate mold member 11A is formed from a low-density material with a small specific gravity, and is manufactured by an existing method such as injection molding. Expanded polystyrene is most preferable. In this embodiment, it is manufactured by injection molding using hard expanded polystyrene with an expansion ratio of 35.

[0053] The top plate mold member 11A has an upper surface 11Aa that forms the upper surface of the top plate 1A-1 via the structural member 20A, a lower surface 11Ab that faces the leg mold member 12A and forms the abutment surface FA, and four side surfaces 11Ac located on the front, rear, left and right sides, all of which are formed as flat surfaces. Here, the shape of the top plate mold member 11A is not limited to this shape, and may be a shape that is approximately circular or elliptical in plan view. In addition, the shape of the lower surface 11Ab that forms the abutment surface FA may be a shape in which a recess or protrusion that serves to position the leg mold member 12A or an element that restricts relative movement (sliding) with the leg mold member 12A is integrally formed or added.

[0054] As shown in FIG. 11, the leg mold member 12A has a basic shape of a substantially square prism, and an upper surface 12Aa that faces the top plate mold member 11A and constitutes the contact surface FA, a lower surface 12Ab that faces the ground, and four side surfaces 12Ac located on the front, rear, left and right sides are all formed by flat surfaces. The dimensions are, for example, several centimeters square x several tens of centimeters to several tens of centimeters in height. However, the shape of the leg mold member 12A is not limited to this shape, and may be any shape that functions as a leg that can secure a desired height such as a cylinder. The leg mold member 12A is formed from a low-density material with a low specific gravity, like the top plate mold member 11A, and each is manufactured by injection molding or the like. In this embodiment, it is manufactured by injection molding using hard polystyrene foam with an expansion ratio of 35.

[0055] As described above, the mold member 10A also functions as a structural member. That is, when an external force is applied to the table 1A, for example, when an article is placed on it, the mold member 10A is deformed by the external force (bending moment) acting through the structural member 20A. The mold member 10A, which has predetermined mechanical properties and rigidity, functions as a structural member by generating bending stress as internal resistance against the external force (bending moment).

[0056] As described above, the contact form between the mold member 10A and the structural member 20A may be a form in which they are in close contact with each other so that they do not move relative to each other when deformed, or a form in which they are in non-close contact with each other so that they move relative to each other when deformed.

[0057] [Structural member 20A] The structural member 20A is a functional element that provides the table 1A with the desired strength, and as described above, forms the surface layer of the table 1A by covering the entire surface of the mold member 10A, including the outer periphery of the contact surface FA between the top mold member 11A and the leg mold member 12A. At this time, the structural member 20A connects the top mold member 11A and the leg mold member 12A, which are constructed as separate bodies, with a predetermined connection strength based on its own mechanical properties.

[0058] Like the above-mentioned pallet 1A, the structural member 20A is made of a high-hardness polyurea resin having high tensile strength and flexibility. In this embodiment, it is made using Extreme HP11-50 manufactured by Rhino Linings. The thickness of the structural member 20A is formed so as to be 1.0 to 4.0 mm, preferably 1.5 to 3.5 mm, and more preferably 2.0 to 3.0 mm on the surface of the mold member 10A.

[0059] The method for forming the structural member 20A on the surface of the mold member 10A is preferably spray painting using a spray gun or the like, which is easy to control the thickness of the coating and has excellent workability. The method for forming the structural member 20A is not limited to spraying, and other existing methods may be used as appropriate. In order to improve the adhesion between the structural member 20A and the mold member 10A, a primer treatment may be applied to the surface of the mold member 10A. In order to improve the aesthetic appearance, a finishing layer or a base layer may be provided on the surface of the structural member 20A.

[0060] <Effects of Table 1A> According to the table 1A of this embodiment having the above-mentioned configuration, similar to the pallet 1A described above, the mold member 10A made of extremely lightweight polystyrene foam and the structural member 20A made of lightweight polyurethane resin formed to cover this mold member 10A function as structural members that resist external forces (bending moments) applied to the table 1A, making it possible to easily and inexpensively manufacture and provide a table 1A that is lightweight and has the desired strength.

[0061] In addition, by connecting the top plate mold member 11A and the leg mold member 12A, which are constructed as separate bodies, through the structural member 20A, mechanical connecting elements such as screws and bolts for connecting these separate mold members are not required, and the process of assembling the mechanical connecting elements is also not required. Also, the process of connecting the top plate mold member 11A and the leg mold member 12A by applying an adhesive to the contact surface FA of the top plate mold member 11A and the leg mold member 12A in advance is not required. This reduces the number of parts and / or eliminates the need for a connecting process, thereby making it possible to appropriately suppress manufacturing costs.

[0062] Furthermore, by freely combining separate mold members, tables 1A of different sizes and shapes can be easily manufactured and provided. In other words, the mold members (top mold member 11A and leg mold member 12A) configured as separate bodies are the smallest unit, and tables 1A that can flexibly accommodate various different specifications and shapes can be easily manufactured and provided.

[0063] Second Embodiment Next, a pallet 1B and a table 1B according to a second embodiment of the present invention will be described with reference to Figures 12 to 26. This second embodiment differs from the pallet 1A and the table 1A according to the first embodiment in that the mold member 10B, which is constructed as a separate body, specifically, functional elements for connecting the mold member 10B, specifically, the top mold member 11B and the leg mold members 12B and 12B' described later, with a predetermined strength, specifically, locking parts 40a, 40b, 40c, and 40d described later (hereinafter, locking parts provided individually like these locking parts may be collectively referred to as "locking parts 40"), and elements for forming the locking parts 40, specifically, recesses 30a, 30b, 30c, and 30d described later (hereinafter, recesses provided individually like these recesses may be collectively referred to as "recesses 30"), are provided on the mold member 10B, but the other configurations are common to the pallet 1A and the table 1A. Therefore, excluding the above-mentioned differences and the functions resulting therefrom, the shapes, functions, etc. of pallet 1B and table 1B, as well as the mold members 10B and structural members 20B contained therein, are identical to those of pallet 1A and table 1A, as well as the mold members 10A and structural members 20A contained therein, unless otherwise specified.

[0064] <Palette 1B Configuration> As shown in Fig. 12 and Fig. 13, the basic form of the pallet 1B is composed of a top plate 1B-1 and a total of nine legs 1B-2, 1B-2' arranged in a lattice pattern on the underside 1B-1b of the top plate 1B-1. As shown in Fig. 14, the top plate 1B-1 and the total of nine legs 1B-2, 1B-2' are formed by covering the surfaces of the top plate mold member 11B and the leg mold members 12B, 12B', which are combined via the horizontal abutment surfaces FB1, FB2 to form the mold member 10B, with the structural member 20B. More specifically, the top plate 1B-1 is formed by covering the entire surface of the top plate mold member 11B except for the abutment surfaces FB1, FB2 with the structural member 20B, and the legs 1B-2, 1B-2' are formed by covering the entire surface of the leg mold members 12B, 12B' except for the abutment surfaces FB1, FB2 with the structural member 20B. The structural member 20B covers the entire surface of the mold member 10B, including the outer peripheral edges of the contact surfaces FB1, FB2 between the top plate mold member 11B and the leg mold members 12B, 12B'. As a result, the pallet 1B has a structure in which the core is formed by the mold member 10B and the surface layer is formed by the structural member 20B, similar to the pallet 1A.

[0065] The tabletop 1B-1 and the nine legs 1B-2, 1B-2' are configured to have at least one of the engaging portions 40a, 40b, 40c and 40d protruding from the inner wall surface of the structural member 20B, as shown by the dashed lines in Figures 12 and 13, and in Figure 14.

[0066] [Mold member 10B] As shown in Fig. 15 to Fig. 20, the mold member 10B is composed of one top plate mold member 11B, eight leg mold members 12B, and one leg mold member 12B', each of which is constructed as a separate body. The eight leg mold members 12B and one leg mold member 12B' are arranged in a lattice shape on the lower surface 11Bb of the top plate mold member 11B at approximately equal intervals in three rows in the front-rear and left-right directions, as shown in Fig. 18, more specifically, the leg mold member 12B' is arranged in the center, and the eight leg mold members 12B are arranged in the front-rear and left-right directions and diagonally so as to surround the leg mold member 12B', so that the upper surface 12Ba of the leg mold member 12B and the upper surface 12Ba' of the leg mold member 12B' are arranged to abut against the lower surface 11Bb of the top plate mold member 11B. In this embodiment, the lower surface 11Bb of the top plate mold member 11B, the upper surface 12Ba of the leg mold member 12B, and the upper surface 12Ba' of the leg mold member 12B' are all flat surfaces, and as shown in Fig. 20, these flat surfaces form abutment surfaces FB1 and FB2 that form a horizontal plane. Note that the abutment surfaces FB1 and FB2 do not need to be flat surfaces, and may be provided with irregularities for positioning the leg mold member 12B and the leg mold member 12B' relative to the top plate mold member 11B and / or for restricting relative movement between them, and elements for restricting relative movement may be provided on the abutment surfaces FB1 and FB2, as in the mold member 10A according to the first embodiment.

[0067] [Top plate part 11B] As shown in Figures 15a and 15b, the top plate portion mold member 11B has a basic shape in common with the top plate portion mold member 11A. That is, the top plate portion mold member 11B is formed as a plate-like member having a substantially rectangular shape in plan view, a predetermined thickness, and both an upper surface 11Ba and a lower surface 11Bb are flat.

[0068] The top plate mold member 11B has groove-like recesses 30a on each of the four side surfaces 11Bc (front, rear, left and right), and 30b is provided as a hole that penetrates the upper surface 11Ba and the lower surface 11Bb substantially vertically. As described in detail below, these recesses 30a and 30b are functional elements provided to form the locking portions 40a and 40b by allowing the polyurethane resin applied to the mold member 10B (top plate mold member 11B) to form the structural member 20B to penetrate into the recesses 30a and 30b, and as described above, they are components unique to this embodiment that are not provided in the top plate mold member 11A. In the mold member 10B configured in a specified shape as shown in Figure 20, the recess 30a is arranged at a position sandwiching the abutment surface FB1 with the recess 30c provided in the leg mold member 12B described later so as to form a pair with it, and the recess 30b is arranged at a position sandwiching the abutment surface FB2 with the recess 30d provided in the leg mold member 12B' also described later so as to form a pair with it.

[0069] [Recess 30a] As shown in FIG. 15a, the recesses 30a formed on the four side surfaces 11Bc are each formed as a single groove that extends in the front-rear or left-right direction as the longitudinal direction and has a length approximately equal to the overall width of each side surface 11Bc. The shape of the groove is preferably a shape that allows a part of the polyurea resin to easily enter and remain therein. For example, as shown in FIG. 15b, the recesses 30a according to this embodiment are formed as a V-shaped groove with a substantially triangular cross section perpendicular to the longitudinal direction, which makes it easy for the polyurea resin to enter the recesses 30a through the large opening. The opening width and depth of the recesses 30a are set in consideration of the balance between the connection strength between the mold members and the paintability and filling property of the polyurea resin, and are exemplified as being in the range of several mm to several cm. A plurality of recesses 30a may be formed on the same surface.

[0070] The recess 30a in the above-mentioned form forms a locking portion 40a suitable for increasing the section modulus of the structural member 20B in a cross section parallel to the contact surface FB1. The formation of the locking portion 40a increases the rigidity of the structural member 20B in the vicinity of the locking portion. As a result, the strength of the pallet 1B is improved, and the joint strength between the top plate mold member 11B and the leg mold member 12B is also increased. For this reason, it is advisable to determine the form of the recess 30a by paying attention to forming the locking portion 40a that increases the above-mentioned section modulus. In addition, the closer the locking portion 40a is to the contact surface FB1, the higher the rigidity of the structural member 20B around the contact surface FB1 is, and the more suitably the joint strength between the top plate mold member 11B and the leg mold member 12B is improved. For this reason, it is advisable to arrange the recess 30a in the vicinity of the contact surface FB1.

[0071] The dimensions of the recess 30a, such as the opening length, opening width, and depth, should be set to be equal to or greater than the minimum thickness of the structural member 20B, which is determined in consideration of the excellent mechanical properties, hardening speed, and manufacturing cost of the polyurethane resin. Examples of the thickness range from several times to several tens of times the minimum thickness. The structural member 20B has a locking portion 40a having mechanical strength equivalent to that of other portions, since the wall surface defining the recess 30a is covered with a thickness equal to or greater than the minimum thickness. In order to increase the strength, it is preferable that most or almost all of the wall surface defining the recess 30a is covered with the polyurethane resin. Most of the wall surface means 50% or more, preferably 75% or more of the area of ​​the wall surface. As a result, the locking portion 40a cooperates with the locking portion 40c described later to suitably connect the separate top plate portion mold member 11B and leg portion mold member 12B.

[0072] The shape and dimensions of the recess 30a may be determined so that the locking portion 40a has a desired strength by having a predetermined thickness and length (in other words, a predetermined volume) and / or the locking portion 40a is formed in a shape that contributes to improving the rigidity of the structural member 20B. Here, the shape of the locking portion 40a that contributes to improving the strength and rigidity is appropriately determined based on the expected magnitude of the external force and the input mode. For this reason, the shape of the locking portion 40a is appropriately selected so that the section modulus is large not only in a cross section parallel to the contact surface FB1 but also in any cross section such as a cross section perpendicular to the contact surface FB1. The recess 30a may be appropriately selected to have a shape suitable for forming the locking portion 40a.

[0073] The shape of the recess 30a is not limited to the above as long as it can form the locking portion 40a that can join the top plate mold member 11B and the leg mold member 12B, which are formed as separate bodies, with a certain degree of strength by cooperating with the locking portion 40c formed through the recess 30c described later. For example, the vertical cross-sectional shape may be a polygon other than a triangle, or a shape consisting of a curve such as an arc. Also, it may be a shape of a plurality of grooves provided intermittently over the entire width of each side surface 11Bc, or a shape formed of a plurality of depressions defined by hemispherical and / or polyhedral walls. Furthermore, it may be a shape having a void inside for retaining the polyurea resin. This void may be formed so as to form a part of the recess 30a, or may be formed so as to be separated from the recess 30a while communicating with it.

[0074] The recess 30a is formed by machining such as cutting or pressing, or by molding using a mold, for example. The recess 30a may also be formed by a chemical processing method such as etching. The same applies to each recess described later.

[0075] [Recess 30b] As shown in Fig. 15a, the recess 30b has an opening at the approximate center of the upper surface 11Ba and the lower surface 11Bb, and is formed as a through hole with a larger opening diameter on the upper surface 11Ba side than on the lower surface 11Bb side by being defined by an inverted truncated cone wall surface 31b as shown in Fig. 15b. Here, the leg mold member 12B' is disposed in the portion where the recess 30b opens on the lower surface 11Bb side as shown in Fig. 18. For this reason, as described later, a part of the polyurethane resin applied to the surface of the mold member 10B (the surface of the top plate mold member 11B) to form the structural member 20B enters the recess 30b through the large-diameter opening formed on the upper surface 11Ba side to form the locking portion 40b, and also enters the recess 30d communicating with the recess 30b, i.e., the recess 30d having the void 50 formed on the upper surface 12Ba' of the leg mold member 12B' to form the locking portion 40d.

[0076] The recess 30b is defined by the wall surface 31b of an inverted truncated cone, which provides the following effects. That is, the above-mentioned polyurea resin smoothly flows into the recess 30b while sliding on the wall surface 31b, and fills the gap 50 suitably even when the recess 30d communicating with the recess 30b has a relatively large volume of gap 50. If a desired bonding strength is obtained, the gap 50 does not need to be completely filled with the polyurea resin. In order to improve the filling property of the polyurea resin, one or more air vent holes with a diameter of 1 to several mm that communicate from the gap 50 to the outside may be provided through the upper part of the leg mold member 12B'. Also, as described above, the locking portion 40b formed through the recess 30b increases the section modulus of the structural member 20B in a cross section perpendicular to the contact surface FB2. This increases the rigidity of the structural member 20B in the vicinity of the contact surface FB2, resulting in an increase in the strength of the pallet 1B and an increase in the joining strength between the top plate mold member 11B and the leg mold member 12B'.

[0077] In addition, although details will be described later, when considering the general use of pallets, increasing the section modulus of the structural member 20B in a cross section perpendicular to the horizontal plane is particularly useful for increasing the strength of the pallet 1B. Therefore, in the pallet 1B in which the abutment surface FB2 is formed as a horizontal plane, the locking portion 40b is particularly useful as an element for increasing strength. For this reason, it is advisable to determine the shape of the recess 30b with attention paid to forming the locking portion 40b with a larger section modulus.

[0078] The dimensions of the recess 30b, such as the opening diameter and depth, may be set to be equal to or greater than the minimum thickness of the structural member 20B, which is set in consideration of the desired strength, rigidity, and productivity, as with the recess 30a. This allows the structural member 20B to have a locking portion 40b with the desired strength and rigidity. The locking portion 40b cooperates with a locking portion 40d, which will be described later, to suitably connect the separate top plate mold member 11B and leg mold member 12B'.

[0079] The shape and dimensions of each part of the recess 30b may be determined so that, as described above, an engaging portion 40b having the desired strength is formed and / or an engaging portion 40b having a shape that contributes to improving the rigidity of the structural member 20B is formed.

[0080] However, the shape of the recess 30b does not have to be the above-mentioned desirable shape, and may be any shape as long as it can form a locking portion 40b that can join the top plate mold member 11B and the leg mold member 12B', which are formed as separate bodies, with a certain degree of strength by cooperating with a locking portion 40d formed through the recess 30d described later. For example, it may be a through hole defined by a wall surface in the shape of an inverted pyramid, or a through hole defined by a wall surface in the shape of a cylinder or a prism. If the shape of the leg mold member 12B' is a prism extending back and forth or left and right, it may be a groove-shaped through hole extending back and forth or left and right.

[0081] [Leg mold member 12B] As shown in Figs. 16a and 16b, the leg mold member 12B has a basic shape of a substantially inverted quadrangular pyramid similar to the leg mold member 12A, and both the upper surface 12Ba and the lower surface 12Bb are formed by flat surfaces. The four side surfaces 12Bc of the leg mold member 12B, the front, rear, left and right, are each provided with a groove-shaped recess 30c. These recesses 30c are functional elements provided to form the locking portion 40c that is integrally provided with the structural member 20 (part of the structural member 20), and are components unique to this embodiment that are not provided with the leg mold member 12A. As described above, the recesses 30c are arranged in the mold member 10B configured in a predetermined shape shown in Fig. 20 at a position sandwiching the recess 30a provided with the top plate mold member 11B and the contact surface FB1.

[0082] [Recess 30c] The recesses 30c provided on the four side surfaces 12Bc are each formed as a single groove extending in the front-rear or left-right direction and having a length approximately equal to half the overall width of each side surface 12Bc. The shape of the groove is preferably the same as that of the recess 30a, that is, a shape that allows a part of the polyurethane resin applied to the mold member 10B (leg mold member 12B) to form the structural member 20B to easily enter and remain therein. The recess 30c according to this embodiment is formed as a V-shaped groove having a cross section perpendicular to the longitudinal direction that is approximately triangular, which allows the polyurethane resin to easily enter the recess 30c through a large opening. A plurality of recesses 30c may be formed on the same surface.

[0083] The recess 30c in the above-mentioned form forms a locking portion 40c suitable for increasing the section modulus of the structural member 20B in a cross section parallel to the contact surface FB1, similar to the recess 30a. The formation of the locking portion 40c increases the rigidity of the structural member 20B in the vicinity of the locking portion, thereby improving the strength of the pallet 1B and also increasing the joint strength between the top plate mold member 11B and the leg mold member 12B. Therefore, it is preferable to determine the form of the recess 30c by paying attention to forming the locking portion 40c that increases the above-mentioned section modulus. In addition, the closer the locking portion 40c is to the contact surface FB1, the higher the rigidity of the structural member 20B around the contact surface FB1, so that the joint strength between the top plate mold member 11B and the leg mold member 12B is more suitably improved. Therefore, it is preferable to arrange the recess 30c in the vicinity of the contact surface FB1. For example, the groove-shaped recess 30c may be formed so that the distance from the contact surface FB1 (upper surface 12Ba) is shorter than the groove length itself.

[0084] The dimensions of the recess 30c, such as the opening length, opening width, and depth, should be set to be equal to or greater than the minimum thickness of the structural member 20B, which is set in consideration of the desired strength, rigidity, and productivity, similar to the recess 30a. As a result, the structural member 20B has a locking portion 40c having the desired strength and rigidity, and as described above, cooperates with the locking portion 40a to suitably connect the separate top plate mold member 11B and leg mold member 12B.

[0085] The shape and dimensions of each part of recess 30c, like recess 30a, may be determined so that engaging portion 40c having a desired strength is formed by having a predetermined thickness and length (in other words, a predetermined volume) and / or so that engaging portion 40c having a shape that contributes to improving the rigidity of structural member 20B is formed.

[0086] However, the shape of the recess 30c may be any shape as long as it can form the locking portion 40c that cooperates with the locking portion 40a formed through the recess 30a to connect the top plate mold member 11B and the leg mold member 12B, which are formed as separate bodies, with a certain degree of strength. For example, the vertical cross-sectional shape may be a polygon other than a triangle, or a shape consisting of a curve such as an arc. Also, it may be a shape of a plurality of grooves provided intermittently over the entire width of each side surface 12Bc, or a shape formed of a plurality of depressions defined by hemispherical and / or polyhedral walls. Furthermore, it may be a shape having a void inside for retaining the polyurea resin. This void may be formed so as to form a part of the recess 30c, or may be formed so as to communicate with the recess 30c.

[0087] [Leg mold member 12B'] As shown in Figs. 17a and 17b, the leg mold member 12B' has a basic shape of an approximately inverted pyramid like the leg mold member 12B, and has the same height (Z dimension) as the leg mold member 12B. The lower surface 12Bb' and the four side surfaces 12Bc' of the leg mold member 12B' are all flat, and a recess 30d is provided on the upper surface 12Ba' of the leg mold member 12B'. This recess 30d is a functional element provided to form the locking portion 40d that is integrally provided with the structural member 20B so as to form a part of itself, and is a component unique to this embodiment that is not provided with the leg mold member 12A. As described above, the recess 30d is located at a position sandwiching the contact surface FB2 and the recess 30b provided in the top plate mold member 11B in the mold member 10B configured in a predetermined shape shown in Fig. 20, and communicates with it.

[0088] [Recess 30d] The recess 30d has an opening on the upper surface 12Ba' and has a void 50 therein that communicates with the opening. More specifically, the recess 30d is configured so that a cylindrical void extending downward from the opening communicates with a truncated cone-shaped void 50 having a bottom surface with a larger opening area than the opening. The opening of the recess 30d is configured to communicate with the recess 30b formed as a through hole of the top plate mold member 11B at the contact surface FB2 in the mold member 10B in which the leg mold member 12A' is arranged at a predetermined position on the lower surface 11Bb of the top plate mold member 11B. As a result, the void 50 communicates with the recess 30b in the mold member 10B.

[0089] Here, the truncated cone-shaped gap 50 has a predetermined projected area on the contact surface FB2 between the top plate mold member 11B and the leg mold member 12B'. This projected area is larger than the opening area of ​​the upper surface 12Ba' of the recess 30d. Therefore, the recess 30d having the gap 50 forms a locking portion 40d with an anchor effect. The locking portion 40d with the anchor effect cooperates with the locking portion 40b to appropriately connect the separate top plate mold member 11B and the leg mold member 12B'. Therefore, it is preferable to determine the shape of the recess 30d so that the polyurethane resin can easily flow into the gap 50 and the formed locking portion 40d has a larger anchor effect.

[0090] In addition, the recess 30d having the truncated cone-shaped gap 50 forms a locking portion 40d suitable for increasing the section modulus of the structural member 20B in a cross section perpendicular to the contact surface FB2. The formation of the locking portion 40d increases the rigidity of the structural member 20B in the vicinity of the locking portion, thereby improving the strength of the pallet 1B and increasing the bonding strength between the top plate mold member 11B and the leg mold member 12B'. For this reason, the shape of the recess 30d should be determined with attention paid to forming the locking portion 40d that further increases the above-mentioned section modulus.

[0091] The opening diameter (width) and depth of the recess 30d and the dimensions of each part of the gap 50, for example, as with the recesses 30a, 30b, and 30c, should be set to be equal to or greater than the minimum thickness of the structural member 20B, which is set in consideration of the desired strength, rigidity, and productivity. This allows the structural member 20B to have a locking portion 40d with the desired strength and rigidity. The locking portion 40d provides the anchor effect more effectively and cooperates with the locking portion 40b to effectively connect the separate top plate mold member 11B and leg mold member 12B'.

[0092] The shape and dimensions of each part of the recess 30d may be determined so that the locking part 40d has a desired strength and / or contributes to improving the rigidity of the structural member 20B. Furthermore, the shape and dimensions of each part of the recess 30d may be determined so that the locking part 40d is formed to have the above-mentioned anchor effect.

[0093] The shape of the recess 30d may be any shape as long as it can form the locking portion 40d that cooperates with the locking portion 40b formed through the recess 30b to connect the separate top plate mold member 11B and the leg mold member 12B' with a certain degree of strength. For example, the shape may not include the void 50, or the void 50 may be connected to other voids (i.e., a shape having multiple voids inside). The void 50 may be any shape, such as a cylindrical shape, a prismatic shape, or a dome shape.

[0094] [Structural member 20B] 14, the structural member 20B differs from the structural member 20A in that the structural member 20B is provided integrally with the locking portions 40 (locking portions 40a, 40b, 40c, and 40d) to suitably increase the joining strength of the mold member 10B which is constructed separately, but the other configurations are the same as those of the structural member 20A. Therefore, the specific selection of materials, the method of setting the thickness, the method of formation, etc. are the same as those of the structural member 20A, and the description thereof will be omitted.

[0095] As described above, the locking portion 40 is a functional element provided to connect the mold member 10B, which is constructed as a separate body, with a predetermined strength, and is a component unique to this embodiment that the structural member 20A does not have. The locking portion 40 is formed when the polyurethane resin, which is applied to the surface of the mold member 10B to form the structural member 20B, enters the recess 30 provided in the mold member 10B and hardens. Here, the polyurethane resin that has entered the recess 30 hardens simultaneously with the polyurethane resin applied to the surface of the mold member 10B other than the recess 30. Therefore, the locking portion 40 is formed integrally with the structural member 20B so as to form a part of the structural member 20B. The locking portions 40a, 40b, 40c, and 40d will be described in detail below.

[0096] [Latching portion 40a and latching portion 40c] The locking portion 40a is formed as follows. That is, when the above-mentioned polyurethane resin enters the groove-shaped recess 30a provided on each of the front, rear, left and right side surfaces 11Bc of the top plate portion mold member 11B, the wall surface defining the recess 30a is covered or the gap defining the recess 30a is filled with the polyurethane resin. The polyurethane resin then hardens to form the locking portion 40a having a shape complementary to the wall surface or gap defining the recess 30a. The locking portion 40a is a single protrusion extending in the front-rear or left-right direction as the longitudinal direction and having a length approximately equal to the total width of each side surface 11Bc, and the protrusion protrudes from the inner wall surface of the structural member 20B so as to enter the recess 30a. Here, whether the locking portion 40a has a shape complementary to the wall surface or the void depends on the specific form of the recess 30a (specific values ​​such as the opening width, depth, and void volume) and the physical properties (viscosity, etc.) of the polyurea resin. For example, when the opening width of the recess 30a is narrow and the void volume is small, the locking portion 40a having a shape complementary to the void that defines the recess 30a is formed by filling the recess 30a with the polyurea resin and then curing it. On the other hand, when the opening width is wide and the void volume is large, the locking portion 40a having a shape complementary to the wall surface that defines the recess 30a is formed by curing the polyurea resin without filling the recess 30a. Note that FIG. 14 illustrates the locking portion 40a having a shape complementary to the void that defines the recess 30a.

[0097] The locking portion 40c is also formed by a process similar to that of the locking portion 40a. That is, a polyurethane resin is filled into the groove-shaped recesses 30c provided on each of the front, rear, left and right side surfaces 12Bc of the leg mold member 12B, and then when the polyurethane resin hardens, the locking portion 40c having a shape complementary to the wall surface or gap that defines the recess 30c is formed. As a result, the locking portion 40c is formed as a single protrusion that extends in the front-rear or left-right direction as the longitudinal direction and has a length approximately equal to half the total width of each side surface 12Bc, and the protrusion protrudes from the inner wall surface of the structural member 20B so as to enter the recess 30c.

[0098] The locking portion 40a formed through the recess 30a of the top plate mold member 11B and the locking portion 40c formed through the recess 30c of the leg mold member 12B are disposed at positions sandwiching the abutment surface FB1 between the top plate mold member 11B and the leg mold member 12B. In particular, in this embodiment in which the locking portion 40a and the locking portion 40c are provided near the abutment surface FB1, these locking portions are disposed in pairs as shown in FIG. 14. In addition, since the locking portion 40a and the locking portion 40c are formed as strip-shaped protrusions extending approximately parallel to the abutment surface FB1, the area of ​​the locking portion 40a and the locking portion 40c projected onto the abutment surface FB1 is larger than the area of ​​the locking portion 40a and the locking portion 40c projected onto a surface other than the abutment surface FB1, for example, onto a surface perpendicular to the abutment surface FB1.

[0099] The locking portion 40a and the locking portion 40c in the above embodiment function to appropriately restrict the relative movement between the top plate mold member 11B and the leg mold member 12B, particularly the relative movement in the direction away from the contact surface FB1. That is, the force that moves the top plate mold member 11B and the leg mold member 12B relative to each other acts on the locking portion 40a through the recess 30a, and acts on the locking portion 40c through the recess 30c. At this time, a resistance force against the above force is generated in the locking portion 40a and the locking portion 40c. This resistance force restricts the relative movement between the top plate mold member 11B and the leg mold member 12B. Here, the area of ​​the locking portion 40a and the locking portion 40c in the above embodiment projected onto the contact surface FB1 between the top plate mold member 11B and the leg mold member 12B is larger than the area projected onto a surface other than the contact surface FB1. Therefore, the locking portion 40a and the locking portion 40c cooperate with each other to provide a particularly large resistance to the relative movement of the top plate mold member 11B and the leg mold member 12B away from each other's contact surface FB1, and suitably restrict the relative movement. As a result, the top plate mold member 11B and the leg mold member 12B are suitably joined with a predetermined strength.

[0100] As described above, the locking portion 40a and the locking portion 40c in the above embodiment increase the section modulus of the structural member 20B in a cross section parallel to the contact surface FB1. This increases the rigidity of the structural member 20B, and the joint strength between the top plate mold member 11B and the leg mold member 12B is preferably improved. In particular, in the present embodiment in which the locking portion 40a and the locking portion 40c are disposed in a position close to the contact surface FB1, the rigidity of the structural member 20B in the vicinity of the contact surface FB1 is increased, and the joint strength between the top plate mold member 11B and the leg mold member 12B is more preferably improved.

[0101] [Latching portion 40b and latching portion 40d] The locking portion 40b and the locking portion 40d are formed integrally with each other as follows. That is, the recess 30b provided on the upper surface 11Ba of the top plate mold member 11B and the recess 30d provided on the upper surface 12Ba' of the leg mold member 12B' and having the truncated cone-shaped gap 50 communicate with each other when the top plate mold member 11B and the leg mold member 12B' form the mold member 10B. When a polyurethane resin for forming the structural member 20B is applied to the upper surface of the mold member 10B, more specifically, to the upper surface 11Ba of the top plate mold member 11B, a part of the polyurethane resin enters the recess 30b and the recess 30d communicating with the recess 30b through the opening of the recess 30b formed on the upper surface 11Ba side, and remains so as to cover the wall surface of the recess 30b and the recess 30d having the gap 50 or to fill at least a part of these recesses. Thereafter, when the polyurethane resin hardens, as shown in Fig. 14, for example, locking portion 40b having a shape complementary to inverted truncated cone-shaped wall surface 31b defining recess 30b is formed so as to protrude downward from the inner wall surface of structural member 20B. At the same time as locking portion 40b is formed, locking portion 40d having a shape complementary to the gap defining recess 30d, i.e., the gap formed by connecting the cylindrical gap and the truncated cone-shaped gap 50, is formed so as to protrude downward from the inner wall surface of structural member 20B via locking portion 40b. Here, the polyurethane resin forming locking portion 40b and the polyurethane resin forming locking portion 40d are hardened together at substantially the same time. As a result, the locking portions 40b and 40d are located on either side of the abutment surface FB2 between the top plate portion mold member 11B and the leg portion mold member 12B' and are formed integrally with each other, thereby forming an locking portion that intersects with the abutment surface FB2 at a predetermined angle, for example vertically.

[0102] The locking portion formed by the locking portion 40b and the locking portion 40d of the above-mentioned form suitably increases the joining strength between the top plate mold member 11B and the leg mold member 12B'. That is, the locking portion 40b, which has a form complementary to the inverted truncated cone-shaped wall surface 31b that defines the recess 30b, has a predetermined projected area on the abutment surface FB2 between the top plate mold member 11B and the leg mold member 12B'. Also, the locking portion 40d, which has a form complementary to the truncated cone-shaped cavity 50, has a predetermined projected area on the abutment surface FB2 as described above, thereby exerting an anchor effect. Since these locking portions 40b and 40d are located on either side of the abutment surface FB2 between the top plate portion mold member 11B and the leg portion mold member 12B' and are formed integrally with each other, they provide a large resistance to the relative movement of the top plate portion mold member 11B and the leg portion mold member 12B' away from each other's abutment surface FB2, thereby effectively restricting such relative movement.

[0103] As described above, the locking portions 40b and 40d in the above-described form preferably increase the section modulus of the structural member 20B in the cross section perpendicular to the contact surface FB2, and increase the rigidity of the structural member 20B in the vicinity of the contact surface FB2. This effect is particularly useful in relation to the general use of pallets.

[0104] To elaborate on the above, in the case of a typical use of a pallet, the pallet 1B is placed on a horizontal surface, and a heavy object is placed on the upper surface 1B-1a of the top plate 1B-1. The pallet 1B is then lifted by a forklift and transported to a specified location, where it is placed again on the horizontal surface. At this time, a vertical external force repeatedly acts downward on the pallet 1B through the top plate 1B-1. A force that opposes the external force, i.e., a reaction force, acts upward on the stationary pallet 1B through the legs 1B-2 and 1B-2'. As a result, the pallet 1B is deformed so as to be warped concavely with respect to the horizontal plane, and a bending stress proportional to the magnitude of the deformation is generated in the pallet 1B. If this bending stress exceeds a certain value, the pallet 1B will break, so it is important to suppress the above deformation to a small value in order to increase the strength of the pallet 1B. The above deformation can be suppressed to a small value by increasing the section modulus of the pallet 1B in a cross section perpendicular to the horizontal plane. Here, the contact surface FB2 of the pallet 1B is horizontal, and therefore the locking portions 40b and 40d, which are factors that increase the section modulus in a cross section perpendicular to the contact surface FB2, are useful for keeping the above-mentioned deformation small.

[0105] To generalize the above situation, the structural member 20B has the locking portions 40b and 40d that form locking portions that intersect with the abutment surface FB2 at a predetermined angle, thereby increasing the resistance (rigidity) against deformation (deformation due to bending moment) that forms a neutral surface parallel to the abutment surface FB2, and at the same time increasing the resistance (strength) against external forces. In addition, by increasing the rigidity of the structural member 20B near the abutment surface FB2, the relative movement between the top plate mold member 11B and the leg mold member 12B' is suppressed to a small value. As a result, the joining strength between the top plate mold member 11B and the leg mold member 12B' is also suitably increased.

[0106] <Effects of Palette 1B> According to the pallet 1B of this embodiment having the above-mentioned configuration, in addition to the effects achieved by the pallet 1A of the first embodiment, the following effects are achieved.

[0107] In other words, since the structural member 20B has the above-mentioned locking portion 40 (locking portions 40a, 40b, 40c and 40d) formed integrally with itself so as to form a part of itself, the bonding strength between the top plate portion mold member 11B and the leg portion mold member 12B, and between the top plate portion mold member 11B and the leg portion mold member 12B', which are constructed as separate bodies, can be preferably increased.

[0108] Furthermore, by providing the locking portion 40 (locking portions 40a, 40b, 40c, and 40d), the rigidity of the structural member 20B is suitably increased, thereby suppressing deformation of the pallet 1B and suitably increasing resistance to external forces (i.e., strength). In addition, by suitably increasing the rigidity of the structural member 20B in the vicinity of the contact surface FB1 between the top plate mold member 11B and the leg mold member 12B and in the vicinity of the contact surface FB2 between the top plate mold member 11B and the leg mold member 12B', the joining strength between the top plate mold member 11B and the leg mold member 12B, and between the top plate mold member 11B and the leg mold member 12B' can be more suitably increased.

[0109] Due to the above effects, it is possible to provide a lightweight pallet 1B in which the joining strength of the top plate mold member 11B, the leg mold member 12B, and the leg mold member 12B' and the resistance to external forces (strength) are more suitably improved.

[0110] As shown in Figs. 21 and 22, the table 1B has a basic form formed by a top plate 1B-1 and a total of four legs 1B-2 arranged at the four corners of the lower surface 1B-1b of the top plate 1B-1. As shown in Fig. 22, the top plate 1B-1 and the total of four legs 1B-2 are formed by covering the surfaces of the top plate mold member 11B and the leg mold member 12B, which are combined via a horizontal abutment surface FB to form a mold member 10B, with a structural member 20B. More specifically, the top plate 1B-1 is formed by covering the entire surface of the top plate mold member 11B except for the abutment surface FB with the structural member 20B, and the legs 1B-2 are formed by covering the entire surface of the leg mold member 12B except for the abutment surface FB with the structural member 20B. The structural member 20B covers the entire surface of the mold member 10B, including the outer periphery of the abutment surface FB between the top plate mold member 11B and the leg mold member 12B. As a result, table 1B, like table 1A, has a structure in which a core portion is formed by mold member 10B and a surface layer portion is formed by structural member 20B.

[0111] The tabletop 1B-1 and the four legs 1B-2 are configured to have at least one of the engagement portions 40a, 40b, 40c and 40d that protrude from the inner wall surface of the structural member 20B, as shown by the dashed lines in FIG. 21 and in FIG. 22.

[0112] [Mold member 10B] As described above, the mold member 10B is composed of one top plate mold member 11B and four leg mold members 12B, each of which is constructed as a separate body (see Figs. 22, 25, and 26). In this embodiment, the bottom surface 11Bb of the top plate mold member 11B and the top surface 12Ba of the leg mold member 12B are both flat surfaces, and as shown in Fig. 26, these flat surfaces form a horizontal abutment surface FB.

[0113] [Top plate part 11B] As shown in Figures 23a and 23b, the top plate portion mold member 11B has a basic shape in common with the top plate portion mold member 11A. That is, the top plate portion mold member 11B has a substantially rectangular shape in plan view, a predetermined thickness, and is formed as a flat plate-like member with both an upper surface 11Ba and a lower surface 11Bb being flat.

[0114] The top plate mold member 11B has groove-like recesses 30a on each of the four side surfaces 11Bc (front, rear, left and right), and 30b is provided as a hole that penetrates the upper surface 11Ba and the lower surface 11Bb substantially vertically. As described in detail below, these recesses 30a and 30b are functional elements provided to form the locking portions 40a and 40b by allowing the polyurethane resin applied to the mold member 10B (top plate mold member 11B) to form the structural member 20B to penetrate into the recesses 30a and 30b, and as described above, they are components unique to this embodiment that are not provided in the top plate mold member 11A. In the mold member 10B configured in a specified shape as shown in Figure 26, the recess 30a is arranged at a position on either side of the abutment surface FB so as to pair with the recess 30c provided in the leg mold member 12B described later, and the recess 30b is arranged at a position on either side of the abutment surface FB so as to pair with the recess 30d provided in the leg mold member 12B described later.

[0115] [Recess 30a] As shown in FIG. 23a, the recesses 30a formed on the four side surfaces 11Bc are each formed as a single groove that extends in the front-rear or left-right direction as the longitudinal direction and has a length approximately equal to the overall width of each side surface 11Bc. The shape of the groove is preferably a shape that allows a part of the polyurea resin to easily enter and remain therein. For example, as shown in FIG. 23b, the recesses 30a according to this embodiment are formed as a V-shaped groove with a substantially triangular cross section perpendicular to the longitudinal direction, which makes it easy for the polyurea resin to enter the recesses 30a through the large opening. The opening width and depth of the recesses 30a are set in consideration of the balance between the connection strength between the mold members and the paintability and filling property of the polyurea resin, and are exemplified as being in the range of several mm to several cm. A plurality of recesses 30a may be formed on the same surface.

[0116] The recess 30a in the above-mentioned form forms a locking portion 40a suitable for increasing the section modulus of the structural member 20B in a cross section parallel to the contact surface FB. The formation of the locking portion 40a increases the rigidity of the structural member 20B in the vicinity of the locking portion. As a result, the strength of the table 1B is improved, and the joint strength between the top plate mold member 11B and the leg mold member 12B is also increased. For this reason, it is advisable to determine the form of the recess 30a by paying attention to forming the locking portion 40a that increases the above-mentioned section modulus. In addition, the closer the locking portion 40a is to the contact surface FB, the higher the rigidity of the structural member 20B around the contact surface FB is, and the more suitable the joint strength between the top plate mold member 11B and the leg mold member 12B is improved. For this reason, it is advisable to arrange the recess 30a in the vicinity of the contact surface FB.

[0117] The dimensions of the recess 30a, such as the opening length, opening width, and depth, may be set to be equal to or greater than the minimum thickness of the structural member 20B, which is determined in consideration of the excellent mechanical properties, hardening speed, and manufacturing cost of the polyurethane resin. Examples of the thickness range from several times to several tens of times the minimum thickness. The structural member 20B has a locking portion 40a having mechanical strength equivalent to that of other portions, since the wall surface defining the recess 30a is covered with a thickness equal to or greater than the minimum thickness. In order to increase the strength, it is preferable that most or almost all of the wall surface defining the recess 30a is covered with the polyurethane resin. Most of the wall surface means 50% or more, preferably 75% or more of the area of ​​the wall surface. As a result, the locking portion 40a cooperates with the locking portion 40c described later to suitably connect the separate top plate portion mold member 11B and leg portion mold member 12B.

[0118] The shape and dimensions of the recess 30a may be determined so that the locking portion 40a has a desired strength by having a predetermined thickness and length (in other words, a predetermined volume) and / or the locking portion 40a is formed in a shape that contributes to improving the rigidity of the structural member 20B. Here, the shape of the locking portion 40a that contributes to improving the strength and rigidity is appropriately determined based on the expected magnitude of the external force and the input mode. For this reason, the shape of the locking portion 40a is appropriately selected so that the section modulus is large not only in a cross section parallel to the contact surface FB but also in any cross section such as a cross section perpendicular to the contact surface FB. The recess 30a may be appropriately selected to have a shape suitable for forming the locking portion 40a.

[0119] [Recess 30b] As shown in Fig. 23a and Fig. 23b, the recess 30b has openings at the four corners of the upper surface 11Ba and the lower surface 11Bb, and is formed as a through hole with a larger opening diameter on the upper surface 11Ba side than on the lower surface 11Bb side by being defined by an inverted truncated cone wall surface 31b as shown in Fig. 23b. Here, the leg mold member 12B is placed in the portion where the recess 30b opens on the lower surface 11Bb side. As a result, the polyurethane resin that is applied to the surface of the mold member 10B (the surface of the top plate mold member 11B) to form the structural member 20B enters the recess 30b through the large-diameter opening formed on the upper surface 11Ba side to form the locking portion 40b, as described later, and also enters the recess 30d that communicates with the recess 30b, i.e., the recess 30d with the void 50 formed on the upper surface 12Ba of the leg mold member 12B to form the locking portion 40d.

[0120] The recess 30b is defined by the wall surface 31b of an inverted truncated cone, which provides the following effects. That is, the above-mentioned polyurea resin smoothly flows into the recess 30b while sliding on the wall surface 31b, and fills the gap 50 suitably even when the recess 30d communicating with the recess 30b has a relatively large volume of gap 50. If a desired bonding strength is obtained, the gap 50 does not need to be completely filled with the polyurea resin. In order to improve the filling property of the polyurea resin, one or more air vent holes with a diameter of 1 to several mm that communicate from the gap 50 to the outside may be provided through the upper end of the leg mold member 12B. Also, as described above, the locking portion 40b formed through the recess 30b increases the section modulus of the structural member 20B in a cross section perpendicular to the contact surface FB. This increases the rigidity of the structural member 20B in the vicinity of the contact surface FB, thereby improving the strength of the table 1B and also increasing the joining strength between the top plate mold member 11B and the leg mold member 12B.

[0121] In addition, as will be described in detail later, when considering the general manner in which a table is used, increasing the section modulus of the structural member 20B in a cross section perpendicular to the horizontal plane is particularly useful for increasing the strength of the table 1B. Therefore, in a table 1B in which the abutment surface FB is formed as a horizontal plane, the locking portion 40b is particularly useful as an element for increasing strength. For this reason, it is advisable to determine the shape of the recess 30b by taking into consideration the formation of the locking portion 40b with a larger section modulus.

[0122] The dimensions of the recess 30b, such as the opening diameter and depth, may be set to be equal to or greater than the minimum thickness of the structural member 20B, which is set in consideration of the desired strength, rigidity, and productivity, as with the recess 30a. This allows the structural member 20B to have a locking portion 40b with the desired strength and rigidity. The locking portion 40b cooperates with a locking portion 40d, which will be described later, to suitably connect the separate top plate mold member 11B and leg mold member 12B.

[0123] [Leg mold member 12B] As shown in Figs. 24a and 24b, the leg mold member 12B has a basic shape of a substantially square prism like the leg mold member 12A, and both the upper surface 12Ba and the lower surface 12Bb are formed by flat surfaces. The four side surfaces 12Bc of the leg mold member 12B, the front, rear, left and right, are each provided with a groove-shaped recess 30c. These recesses 30c are functional elements provided to form the locking portion 40c that is integrally provided with the structural member 20 (part of the structural member 20), and are components unique to this embodiment that are not provided with the leg mold member 12A. As described above, the recesses 30c are arranged in the mold member 10B configured in a predetermined shape shown in Fig. 26 at a position sandwiching the recess 30a provided with the top plate mold member 11B and the contact surface FB.

[0124] The leg mold member 12B has a recess 30d on the upper surface 12Ba. The recess 30d is a functional element provided to form a locking portion 40d that is integrally provided with the structural member 20B so as to form a part of the structural member 20B, and is a component unique to this embodiment that is not provided with the leg mold member 12A, like the recess 30c. As described above, in the mold member 10B configured in a predetermined shape shown in Figure 26, the recess 30d is located at a position sandwiching the contact surface FB with the recess 30b provided in the top plate mold member 11B, and communicates with it.

[0125] [Recess 30c] The recesses 30c provided on the four side surfaces 12Bc are each formed as a single groove extending in the front-rear or left-right direction and having a length approximately equal to half the overall width of each side surface 12Bc. The shape of the groove is preferably the same as that of the recess 30a, that is, a shape that allows a part of the polyurethane resin applied to the mold member 10B (leg mold member 12B) to form the structural member 20B to easily enter and remain therein. The recess 30c according to this embodiment is formed as a V-shaped groove having a cross section perpendicular to the longitudinal direction that is approximately triangular, which allows the polyurethane resin to easily enter the recess 30c through a large opening. A plurality of recesses 30c may be formed on the same surface.

[0126] The recess 30c in the above-mentioned form forms the locking portion 40c suitable for increasing the section modulus of the structural member 20B in a cross section parallel to the contact surface FB, similarly to the recess 30a. The formation of the locking portion 40c increases the rigidity of the structural member 20B in the vicinity of the locking portion, thereby improving the strength of the table 1B and also increasing the joint strength between the top plate mold member 11B and the leg mold member 12B. For this reason, it is advisable to determine the form of the recess 30c by paying attention to forming the locking portion 40c that increases the above-mentioned section modulus. In addition, the closer the locking portion 40c is to the contact surface FB, the higher the rigidity of the structural member 20B around the contact surface FB, so that the joint strength between the top plate mold member 11B and the leg mold member 12B is more suitably improved. For this reason, it is advisable to arrange the recess 30c in the vicinity of the contact surface FB. For example, the groove-shaped recess 30c may be formed so that the distance from the contact surface FB (upper surface 12Ba) is shorter than the groove length itself.

[0127] The dimensions of the recess 30c, such as the opening length, opening width, and depth, should be set to be equal to or greater than the minimum thickness of the structural member 20B, which is set in consideration of the desired strength, rigidity, and productivity, similar to the recess 30a. As a result, the structural member 20B has a locking portion 40c having the desired strength and rigidity, and as described above, cooperates with the locking portion 40a to suitably connect the separate top plate mold member 11B and leg mold member 12B.

[0128] [Recess 30d] The recess 30d has a gap 50 therein that communicates with the opening of the upper surface 12Ba. The gap 50 is formed as a truncated cone-shaped gap with a bottom area larger than the area of ​​the opening. The opening of the recess 30d is configured to communicate with the recess 30b formed as a through hole of the top plate mold member 11B at the contact surface FB in the mold member 10B in which the leg mold member 12A is arranged at a predetermined position on the lower surface 11Bb of the top plate mold member 11B. That is, the gap 50 communicates with the recess 30b in the mold member 10B.

[0129] Here, in the truncated cone-shaped void 50, the bottom area, i.e., the projected area on the contact surface FB between the top plate mold member 11B and the leg mold member 12B, is larger than the area of ​​the opening. Therefore, the recess 30d having the void 50 forms a locking portion 40d with an anchor effect. The locking portion 40d with the anchor effect cooperates with the locking portion 40b to appropriately connect the separate top plate mold member 11B and the leg mold member 12B. Therefore, it is preferable to determine the shape of the recess 30d so that the polyurethane resin can easily flow into the void 50 and the formed locking portion 40d has a larger anchor effect.

[0130] In addition, the recess 30d having the truncated cone-shaped gap 50 forms a locking portion 40d suitable for increasing the section modulus of the structural member 20B in a cross section perpendicular to the contact surface FB. The formation of the locking portion 40d increases the rigidity of the structural member 20B in the vicinity of the locking portion, thereby improving the strength of the table 1B and increasing the bonding strength between the top plate mold member 11B and the leg mold member 12B. For this reason, the shape of the recess 30d should be determined with attention paid to forming the locking portion 40d that further increases the above-mentioned section modulus.

[0131] The opening diameter (width) and depth of the recess 30d and the dimensions of each part of the gap 50, for example, as with the recesses 30a, 30b, and 30c, should be set to be equal to or greater than the minimum thickness of the structural member 20B, which is set in consideration of the desired strength, rigidity, and productivity. This allows the structural member 20B to have a locking portion 40d with the desired strength and rigidity. The locking portion 40d provides the anchor effect more effectively and cooperates with the locking portion 40b to effectively connect the separate top plate mold member 11B and leg mold member 12B.

[0132] [Structural member 20B] 22, the structural member 20B differs from the structural member 20A in that the structural member 20B is provided integrally with the locking portions 40 (locking portions 40a, 40b, 40c, and 40d) to suitably increase the joining strength of the mold member 10B which is constructed separately, but the other configurations are the same as those of the structural member 20A. Therefore, the specific selection of materials, the method of setting the thickness, the method of formation, etc. are the same as those of the structural member 20A, and the description thereof will be omitted.

[0133] As described above, the locking portion 40 is a functional element provided to connect the mold member 10B, which is constructed as a separate body, with a predetermined strength, and is a component unique to this embodiment that the structural member 20A does not have. The locking portion 40 is formed when the polyurethane resin, which is applied to the surface of the mold member 10B to form the structural member 20B, enters the recess 30 provided in the mold member 10B and hardens. Here, the polyurethane resin that has entered the recess 30 hardens simultaneously with the polyurethane resin applied to the surface of the mold member 10B other than the recess 30. Therefore, the locking portion 40 is formed integrally with the structural member 20B so as to form a part of the structural member 20B. The locking portions 40a, 40b, 40c, and 40d will be described in detail below.

[0134] [Latching portion 40a and latching portion 40c] The locking portion 40a is formed as follows. That is, when the above-mentioned polyurethane resin enters the groove-shaped recess 30a provided on each of the front, rear, left and right side surfaces 11Bc of the top plate portion mold member 11B, the wall surface defining the recess 30a is covered or the gap defining the recess 30a is filled with the polyurethane resin. The polyurethane resin then hardens to form the locking portion 40a having a shape complementary to the wall surface or gap defining the recess 30a. The locking portion 40a is a single protrusion extending in the front-rear or left-right direction as the longitudinal direction and having a length approximately equal to the total width of each side surface 11Bc, and the protrusion protrudes from the inner wall surface of the structural member 20B so as to enter the recess 30a. Here, whether the locking portion 40a has a shape complementary to the wall surface or the void depends on the specific form of the recess 30a (specific values ​​such as the opening width, depth, and void volume) and the physical properties (viscosity, etc.) of the polyurea resin. For example, when the opening width of the recess 30a is narrow and the void volume is small, the locking portion 40a having a shape complementary to the void that defines the recess 30a is formed by filling the recess 30a with the polyurea resin and then curing it. On the other hand, when the opening width is wide and the void volume is large, the locking portion 40a having a shape complementary to the wall surface that defines the recess 30a is formed by curing the polyurea resin without filling the recess 30a. Note that FIG. 22 illustrates the locking portion 40a having a shape complementary to the void that defines the recess 30a.

[0135] The locking portion 40c is also formed by a process similar to that of the locking portion 40a. That is, a polyurethane resin is filled into the groove-shaped recesses 30c provided on each of the front, rear, left and right side surfaces 12Bc of the leg mold member 12B, and then when the polyurethane resin hardens, the locking portion 40c having a shape complementary to the wall surface or gap that defines the recess 30c is formed. As a result, the locking portion 40c is formed as a single protrusion that extends in the front-rear or left-right direction as the longitudinal direction and has a length approximately equal to half the total width of each side surface 12Bc, and the protrusion protrudes from the inner wall surface of the structural member 20B so as to enter the recess 30c.

[0136] The locking portion 40a formed through the recess 30a of the top plate mold member 11B and the locking portion 40c formed through the recess 30c of the leg mold member 12B are disposed at positions sandwiching the abutment surface FB between the top plate mold member 11B and the leg mold member 12B. In particular, in this embodiment in which the locking portion 40a and the locking portion 40c are provided near the abutment surface FB, as shown in Fig. 22, these locking portions are disposed in pairs. In addition, since the locking portion 40a and the locking portion 40c are formed as strip-shaped protrusions extending approximately parallel to the abutment surface FB, the area of ​​the locking portion 40a and the locking portion 40c projected onto the abutment surface FB is larger than the area of ​​the locking portion 40a and the locking portion 40c projected onto a surface other than the abutment surface FB, for example, onto a surface perpendicular to the abutment surface FB.

[0137] The locking portion 40a and the locking portion 40c in the above embodiment function to appropriately restrict the relative movement between the top plate mold member 11B and the leg mold member 12B, particularly the relative movement in the direction away from the contact surface FB. That is, the force that moves the top plate mold member 11B and the leg mold member 12B relative to each other acts on the locking portion 40a through the recess 30a, and acts on the locking portion 40c through the recess 30c. At this time, a resistance force against the above force is generated in the locking portion 40a and the locking portion 40c. This resistance force restricts the relative movement between the top plate mold member 11B and the leg mold member 12B. Here, the area of ​​the locking portion 40a and the locking portion 40c in the above embodiment projected onto the contact surface FB between the top plate mold member 11B and the leg mold member 12B is larger than the area projected onto a surface other than the contact surface FB. Therefore, the locking parts 40a and 40c cooperate with each other to provide a particularly large resistance to the relative movement of the top plate mold member 11B and the leg mold member 12B away from each other's contact surface FB, and suitably restrict the relative movement. As a result, the top plate mold member 11B and the leg mold member 12B are suitably joined with a predetermined strength.

[0138] As described above, the locking portion 40a and the locking portion 40c in the above embodiment increase the section modulus of the structural member 20B in the cross section parallel to the contact surface FB. This increases the rigidity of the structural member 20B, and the joint strength between the top plate mold member 11B and the leg mold member 12B is preferably improved. In particular, in the present embodiment in which the locking portion 40a and the locking portion 40c are disposed in a position close to the contact surface FB, the rigidity of the structural member 20B in the vicinity of the contact surface FB is increased, and the joint strength between the top plate mold member 11B and the leg mold member 12B is more preferably improved.

[0139] [Latching portion 40b and latching portion 40d] The locking portion 40b and the locking portion 40d are formed integrally with each other as follows. That is, the recess 30b provided on the upper surface 11Ba of the top plate mold member 11B and the recess 30d provided on the upper surface 12Ba of the leg mold member 12B and having a truncated cone-shaped gap 50 communicate with each other when the top plate mold member 11B and the leg mold member 12B form the mold member 10B. When a polyurethane resin for forming the structural member 20B is applied to the upper surface of the mold member 10B, more specifically, to the upper surface 11Ba of the top plate mold member 11B, a part of the polyurethane resin enters the recess 30b and the recess 30d communicating with the recess 30b through the opening of the recess 30b formed on the upper surface 11Ba side, and remains so as to cover the wall surfaces of the recess 30b and the recess 30d having the gap 50 or to fill at least a part of these recesses. After that, when the polyurea resin hardens, as shown in FIG. 22, the locking portion 40b is formed so as to protrude downward from the inner wall surface of the structural member 20B, which is complementary to the inverted truncated cone-shaped wall surface 31b that defines the recess 30b. At the same time as the locking portion 40b is formed, the locking portion 40d is formed so as to protrude downward from the inner wall surface of the structural member 20B through the locking portion 40b, which is complementary to the void that defines the recess 30d, i.e., the truncated cone-shaped void 50. Here, the polyurea resin that forms the locking portion 40b and the polyurea resin that forms the locking portion 40d are hardened together at approximately the same time. Therefore, the locking portion 40b and the locking portion 40d are formed so as to sandwich the abutment surface FB between the top plate mold member 11B and the leg mold member 12B and are formed together, so that the locking portion intersects with the abutment surface FB at a predetermined angle, for example, perpendicularly.

[0140] The locking portion formed by the locking portion 40b and the locking portion 40d of the above-mentioned form suitably increases the joining strength between the top plate mold member 11B and the leg mold member 12B. That is, the locking portion 40b, which is complementary to the inverted truncated cone-shaped wall surface 31b that defines the recess 30b, has a predetermined projected area with respect to the contact surface FB between the top plate mold member 11B and the leg mold member 12B. Also, the locking portion 40d, which is complementary to the truncated cone-shaped gap 50, has a predetermined projected area with respect to the contact surface FB as described above, thereby exerting an anchor effect. Since these locking portions 40b and 40d are located on either side of the abutment surface FB between the top plate portion mold member 11B and the leg portion mold member 12B and are formed integrally with each other, they provide a large resistance to the relative movement of the top plate portion mold member 11B and the leg portion mold member 12B away from each other's abutment surface FB, thereby effectively restricting such relative movement.

[0141] As described above, the locking portions 40b and 40d in the above-described form preferably increase the section modulus of the structural member 20B in the cross section perpendicular to the contact surface FB, and increase the rigidity of the structural member 20B in the vicinity of the contact surface FB. This effect is particularly useful in relation to the general use of the table.

[0142] To elaborate on the above, in the case of a typical use of a table, the table 1B is placed on a horizontal surface and an object having a certain weight is placed on the upper surface 1B-1a of the top plate 1B-1. At this time, a vertical external force acts downward on the table 1B through the top plate 1B-1. A force that opposes the external force, i.e., a reaction force, acts upward on the table 1B in a stationary state through the legs 1B-2. As a result, the table 1B, particularly the top plate 1B-1, deforms so as to be warped concavely with respect to the horizontal plane, and thus a bending stress proportional to the magnitude of the deformation is generated in the table 1B. If this bending stress exceeds a certain value, the table 1B will break, so it is important to suppress the above deformation to a small extent in order to increase the strength of the table 1B. The above deformation can be suppressed to a small extent by increasing the section modulus of the table 1B in a cross section perpendicular to the horizontal plane. Here, the contact surface FB of the table 1B is horizontal, and therefore the locking portions 40b and 40d, which are factors that increase the section modulus in a cross section perpendicular to the contact surface FB, are useful for keeping the above-mentioned deformation small.

[0143] To generalize the above situation, the structural member 20B has the locking portion 40b and the locking portion 40d that form a locking portion that intersects with the abutment surface FB at a predetermined angle, thereby increasing the resistance (rigidity) against deformation (deformation due to bending moment) that forms a neutral surface parallel to the abutment surface FB, and at the same time, the resistance (strength) against external forces is also increased. In addition, by increasing the rigidity of the structural member 20B in the vicinity of the abutment surface FB, the relative movement between the top plate mold member 11B and the leg mold member 12B is suppressed to a small value. As a result, the joint strength between the top plate mold member 11B and the leg mold member 12B is also suitably increased.

[0144] <Effects of Table 1B> According to the table 1B of this embodiment having the above-mentioned configuration, in addition to the effects achieved by the table 1A of the first embodiment, the following effects are achieved.

[0145] In other words, since the structural member 20B has the above-mentioned locking portion 40 (locking portions 40a, 40b, 40c and 40d) formed integrally with itself so as to form a part of itself, the bonding strength between the top plate portion mold member 11B and the leg portion mold member 12B, which are constructed as separate bodies, can be suitably increased.

[0146] Furthermore, by providing the locking portion 40 (locking portions 40a, 40b, 40c, and 40d), the rigidity of the structural member 20B is suitably increased, thereby suppressing deformation of the table 1B and suitably increasing resistance to external forces (i.e., strength). In addition, by suitably increasing the rigidity of the structural member 20B in the vicinity of the contact surface FB between the top plate mold member 11B and the leg mold member 12B, the joining strength between the top plate mold member 11B and the leg mold member 12B can be more suitably increased.

[0147] Due to the above effects, it is possible to provide a lightweight table 1B in which the joining strength between the top plate mold member 11B and the leg mold member 12B and the resistance / strength against external forces are more suitably improved.

[0148] Third Embodiment Finally, a pallet 1C according to a third embodiment of the present invention will be described with reference to FIGS.

[0149] <Palette 1C Configuration> The pallet 1C is different from the pallet 1B according to the second embodiment in the following respects. That is, the mold member 10C is composed of a plurality of top plate mold members 11C, and accordingly, a locking portion 40g and a recess 30f for forming the locking portion 40g are newly provided as elements for connecting the top plate mold members 11C. In addition, the shape of the locking portion 40e and the locking portion 40f for connecting the top plate mold member 11C and the leg mold member 12C and the shape of the recess 30e and the recess 30g for forming them are different from the locking portion 40 and the recess 30 of the pallet 1B. Note that the configuration other than these differences is common to the pallet 1B. And the recesses 30e, 30f, and 30g, and the locking portions 40e, 40f, and 40g formed from these recesses have different shapes from the recess 30 (recesses 30a to 30d) and the locking portion 40 (locking portions 40a to 40d) of the pallet 1B, but have the same functions.

[0150] That is, as shown in Figures 27 and 28, the basic form of pallet 1C is composed of a top plate 1C-1 and a total of nine legs 1C-2 arranged in a grid pattern on the underside 1C-1b of this top plate 1C-1. As shown in Figure 29, the top plate 1C-1 and the nine legs 1C-2 are each formed by covering the surface of a solid mold member 10C with a structural member 20C. In this way, like pallet 1B (and pallet 1A), pallet 1C has a structure in which the core is formed by mold member 10C and the surface layer is formed by structural member 20C.

[0151] [Molding member 10C] As shown in Figs. 32 to 34, the mold member 10C is composed of nine tabletop mold members 11C and nine leg mold members 12C, each of which is constructed as a separate body. As shown in Fig. 32, the nine tabletop mold members 11C are arranged in three rows at approximately equal intervals in the front-rear and left-right directions in a lattice pattern. In addition, the leg mold members 12C are arranged one by one for each tabletop mold member 11C so that their upper surface 12Ca abuts against the lower surface 11Cb of the tabletop mold member 11C. The lower surface 11Cb of the tabletop mold member 11C and the upper surface 12Ca of the leg mold member 12C are both flat surfaces, and as shown in Fig. 34, these flat surfaces form a horizontal abutment surface FC1. In addition, adjacent tabletop mold members 11C abut against each other via side surfaces 11Cc on which recesses 30, which will be described later, are arranged, and the abutment surface FC2 is formed by these side surfaces 11Cc. As with the mold member 10A of the first embodiment and the mold member 10B of the second embodiment, the abutment surface FC1 does not need to be a flat surface, but may have projections and recesses for positioning the leg mold member 12C relative to the top plate mold member 11C and / or for restricting relative movement between them, and an element for restricting relative movement may be arranged on the abutment surface FC1, etc.

[0152] [Top plate part 11C] As shown in Figs. 30a and 30b, the top plate mold member 11C is formed as a flat plate member having a substantially rectangular shape in plan view and a predetermined thickness. The top surface 11Ca and the bottom surface 11Cb are both formed as flat plate members. The front, rear, left and right side surfaces 11Cc are formed as inclined surfaces with a predetermined inclination angle. For example, the front side surface 11Cc and the left side surface 11Cc are inclined surfaces facing upward, and the rear side surface 11Cc and the right side surface 11Cc are inclined surfaces facing downward. It is preferable that the top plate mold member 11C is formed as a flat plate member having a square shape in plan view, and that the inclination angles of each side surface 11Cc are the same. This configuration makes it possible to assemble multiple top plate mold members 11C without considering the orientation of the top plate mold members 11C.

[0153] The four side surfaces 11Cc on the front, rear, left and right sides are formed as inclined surfaces, which brings about the following effects. That is, as described above, in a general use mode, the pallet 1C is deformed so as to warp concavely with respect to the horizontal plane when a substantially vertical load is applied through the top plate 1C-1. In the pallet 1C that undergoes such deformation, it is useful to structure the divided multiple top plate mold members 11C so that they receive the vertical load through at least one leg mold member 12C that each of them has, and also receive the vertical load through the adjacent top plate mold members 11C. Here, when a vertical load is applied to the inclined surface, a normal resistance force is generated on the inclined surface as a reaction force. Therefore, according to the present embodiment in which the adjacent top plate mold members 11C abut against each other through the side surfaces 11Cc formed as inclined surfaces, a structure that receives a vertical load through the adjacent top plate mold members 11C (a structure that generates a normal resistance force) can be formed. The shape of the side surface 11Cc that brings about the above useful effects is not particularly limited as long as it is a shape that can generate a normal resistance force against the vertical load.

[0154] The top plate mold member 11C has a recess 30e formed as a hole that penetrates the upper surface 11Ca and the lower surface 11Cb substantially vertically. The recess 30e is disposed, for example, substantially at the center of the upper surface 11Ca and the lower surface 11Cb. The top plate mold member 11C also has recesses 30f disposed on each of the four side surfaces 11Cc on the front, rear, left and right sides.

[0155] [Recess 30e] As shown in Fig. 30b, the recesses 30e are defined by an inverted truncated cone wall surface 31e, and are formed as through holes with an opening diameter on the upper surface 11Ca side larger than that on the lower surface 11Cb side. As shown in Fig. 32, the leg mold member 12C is disposed at the portion where the recess 30e opens on the lower surface 11Cb side. Here, as described later, the leg mold member 12C has a recess 30g that opens on its own upper surface 12Ca, and as shown in Fig. 34, when the top plate mold member 11C and the leg mold member 12C form the mold member 11C, the recess 30g and the recess 30e are disposed on the lower surface 11Cb so as to communicate with each other with the contact surface FC1 between them. The polyurethane resin, which is applied to the surface of the mold member 10C (the surface of the top plate mold member 11C) to form the structural member 20C, enters the recess 30e through a large-diameter opening formed on the upper surface 11Ca side, and then hardens to form the locking portion 40e described below. The recess 30e defined by the inverted truncated cone-shaped wall surface 31e provides the same effect as the recess 30b defined by the inverted truncated cone-shaped wall surface 31b.

[0156] The shape of the recess 30e may be any shape as long as it can form a locking portion 40e that cooperates with a locking portion 40g formed through the recess 30g described later to connect the top plate mold member 11C and the leg mold member 12C, which are formed as separate bodies, with a certain degree of strength. For example, it may be a through hole defined by a wall surface in the shape of an inverted pyramid, or a through hole defined by a wall surface in the shape of a cylinder or a prism. In addition, if the shape of the leg mold member 12C is a prism extending back and forth or left and right, it may be a groove-shaped through hole extending back and forth or left and right.

[0157] However, it is preferable to determine the shape of the recess 30e so that the above-mentioned polyurethane resin penetrates into the recess 30e and hardens to form the locking portion 40e having the desired strength and / or the locking portion 40e having a shape that contributes to improving the rigidity of the structural member 20C. Also, each dimension of the recess 30e, such as the opening diameter and depth, is preferably set to be equal to or greater than the minimum thickness of the structural member 20C, which is set in consideration of the desired strength and rigidity and productivity, as with the recess 30a, etc. For example, in this embodiment, the opening diameter on the lower surface 11Cb side of the top plate mold member 11C is set to a range of several times to a dozen times the minimum thickness of the structural member 20C.

[0158] [Recess 30f] As shown in Fig. 30a and Fig. 30b, the recesses 30f are arranged on the four side surfaces 11Cc of the front, rear, left and right sides, and each has a substantially rectangular shape in a plan view and extends substantially vertically from the center of the upper surface 11Ca to the center of the lower surface 11Cb. In the mold member 10C assembled to a predetermined size by combining a plurality of top plate mold members 11C, the recesses 30f provided on each of a pair of adjacent side surfaces 11Cc form holes having a rectangular columnar gap penetrating vertically. The polyurethane resin applied to the surface of the mold member 10C (the surface of the top plate mold member 11C) to form the structural member 20C enters the through hole and then hardens to form the locking portion 40e described later.

[0159] The shape of the recess 30f may be any shape as long as it can form the locking portion 40f that connects the separately formed top plate portion mold member 11C with a certain degree of strength. For example, it may be a shape in which a pair of adjacent recesses 30f form a cylindrical gap, or a shape in which an inverted truncated pyramid or inverted truncated cone is formed.

[0160] However, it is desirable to determine the thickness so that the above-mentioned polyurethane resin penetrates into the recess 30f and hardens to favorably form the locking portion 40f having the desired strength and / or the locking portion 40f having a form that contributes to improving the rigidity of the structural member 20C. Also, it is desirable to set each dimension of the recess 30f, such as the opening diameter and depth, to be equal to or greater than the minimum thickness of the structural member 20C, which is set in consideration of the desired strength and rigidity and productivity, as with the recess 30a.

[0161] [Leg mold member 12C] As shown in Figures 31a and 31b, the leg mold member 12C has a basic shape of a substantially inverted truncated pyramid like the leg mold members 12A, 12B and 12B', and all four side surfaces 12Cc on the front, back, left and right sides are formed by flat surfaces. The leg mold member 12C also has a recess 30g formed as a through hole that communicates between the upper surface 12Ca and the lower surface 12Cb.

[0162] [Recess 30g] 31b, the recess 30g is composed of an upper portion communicating with the opening on the upper surface 12Ca side and a lower portion communicating with the opening on the lower surface 12Cb side, the upper portion being defined by a cylindrical wall surface 31g, and the lower portion being defined by a truncated cone-shaped wall surface 32g. As a result, the recess 30g has a form in which a cylindrical gap extending downward from the opening on the upper surface 12Ca side and a truncated cone-shaped gap extending upward from the opening on the lower surface 12Cb side are connected to each other.

[0163] As described above, when the top plate mold member 11C and the leg mold member 12C constitute the mold member 11C, the recess 30g is disposed at a position sandwiching the contact surface FC1 with the recess 30e of the top plate mold member 11C and communicating with it through an opening on the upper surface 12Ca side (see Figs. 32 and 34). The polyurethane resin applied to the surface of the mold member 10C (the surface of the leg mold member 12C) to form the structural member 20C enters the recess 30g through a large-diameter opening formed on the lower surface 12Cb side and then hardens, thereby forming the locking portion 40g described below. The recess 30g defined by the truncated cone-shaped wall surface 31g provides the same effect as the recess 30b defined by the inverted truncated cone-shaped wall surface 31b.

[0164] The shape of the recess 30g may be any shape as long as it can form the locking portion 40g that cooperates with the locking portion 40e formed through the recess 30e to connect the top plate mold member 11C and the leg mold member 12C, which are formed as separate bodies, with a certain degree of strength. For example, it may be a through hole defined by a truncated pyramidal wall surface, or a through hole defined by a cylindrical or prismatic wall surface. In addition, if the leg mold member 12C is shaped like a prismatic column extending back and forth or left and right, it may be a groove-shaped through hole extending back and forth or left and right.

[0165] However, it is preferable to determine the shape of the recess 30g so that the polyurethane resin applied to the surface of the mold member 10C (leg mold member 12C) for forming the structural member 20C penetrates the recess 30g and hardens to form the locking portion 40g having the desired strength and / or the locking portion 40g having a shape that contributes to improving the rigidity of the structural member 20C is preferably formed. In addition, each dimension of the recess 30g, such as the opening diameter and depth, is preferably set to be equal to or greater than the minimum thickness of the structural member 20C, which is set in consideration of the desired strength and rigidity and productivity, as with the recess 30a, etc. For example, in this embodiment, the opening diameter on the upper surface 12Ca side of the leg mold member 12C is set in the range of several times to several tens of times the minimum thickness of the structural member 20C.

[0166] [Structural member 20C] Structural member 20C differs from structural member 20B in that structural member 20C includes locking portions 40e, 40f, and 40g having different configurations from locking portions 40a, 40b, 40c, and 40d that are integral with structural member 20B according to the second embodiment. However, the rest of the configuration is common to structural member 20B, and the basic functions of locking portions 40e, 40f, and 40g having different configurations, as well as the basic functions of structural member 20C including these, are common to locking portions 40e, 40f, and 40g and structural member 20B including these.

[0167] Of the locking portions 40e, 40f and 40g provided on the structural member 20C, locking portion 40e and locking portion 40g are functional elements that cooperate with each other to connect the tabletop portion mold member 11C and the leg portion mold member 12C, which are constructed as separate entities, and locking portion 40f is a functional element for joining multiple tabletop portion mold members 11C.

[0168] [Latching portion 40e and latching portion 40g] As described above, the locking portion 40e is formed integrally with the structural member 20C by a part of the polyurethane resin applied to the surface of the mold member 10C to form the structural member 20C entering the recess 30e provided in the top plate mold member 11C and hardening, so as to form a part of the structural member 20C. Specifically, the locking portion 40e is formed to have a shape complementary to the recess 30e shown in Fig. 30b and Fig. 34, more specifically, the locking portion 40e is formed to have a shape complementary to the wall surface 31e of an inverted truncated cone shape that defines the recess 30e by covering the wall surface 31e with the polyurethane resin. The locking portion 40e is formed to protrude downward from the inner wall surface of the structural member 20C that forms the surface layer of the upper surface 1C-1a of the top plate 1C-1, as shown in Fig. 29.

[0169] As described above, the locking portion 40g is formed integrally with the structural member 20C by hardening the recess 30g provided in the leg mold member 12C after a part of the polyurethane resin has entered therein. Specifically, the locking portion 40g is formed to have a shape complementary to the recess 30g shown in Fig. 31b and Fig. 34, more specifically, the upper portion is formed to have a shape complementary to the cylindrical wall surface 31g constituting the upper portion of the recess 30g by covering the cylindrical wall surface 31g constituting the upper portion of the recess 30g with the polyurethane resin, and the lower portion is formed to have a shape complementary to the truncated cone wall surface 32g constituting the lower portion of the recess 30g by covering the truncated cone wall surface 32g constituting the lower portion of the recess 30g. The locking portion 40g is formed to protrude upward from the inner wall surface of the structural member 20C forming the surface layer of the lower surface 1C-2b of the leg 1C-2, as shown in Fig. 29.

[0170] Here, the recess 30e forming the locking portion 40e and the recess 30g forming the locking portion 40g communicate with each other on the contact surface FC1 when the top plate mold member 11C and the leg mold member 12C form the mold member 10C, as described above. This form is the same as the recess 30b forming the locking portion 40b and the recess 30d forming the locking portion 40d in the second embodiment. Therefore, the locking portion 40e and the locking portion 40g are formed in a state of being integrally joined on the above-mentioned contact surface FC1, similar to the locking portion 40b and the locking portion 40d. In other words, the locking portion 40e and the locking portion 40g are integrally joined to form a locking portion that intersects with the contact surface FC1 at a predetermined angle, for example, perpendicularly.

[0171] As described above, the opening diameters of the recesses 30e forming the locking portion 40e and the recesses 30g forming the locking portion 40g at the contact surface FC, i.e., the opening diameters of the recesses 30e at the lower surface 11Cb of the top plate mold member 11C and the opening diameters of the recesses 30g at the upper surface 12Ca of the leg mold member 12C, are set to be larger than the minimum thickness of the structural member 20C. Therefore, the portion of the locking portion formed by the locking portion 40e and the locking portion 40g that intersects with the contact surface FC1 is formed into a hollow cylindrical shape.

[0172] The above-mentioned engaging portions 40e and 40g both have a predetermined projected area relative to the abutment surface FC1 and are formed integrally with each other at positions on either side of the abutment surface FC1, thereby providing a large resistance to the relative movement between the top plate mold member 11C and the leg mold member 12C, particularly the relative movement away from the abutment surface FC1, and effectively restricting the relative movement.

[0173] In addition, the locking portions 40e and 40g which are integrally connected at the abutment surface FC1 provide an effect equal to or greater than that of the locking portions 40b and 40d in the second embodiment (locking portions 40b and 40d which are integrally connected at the abutment surface FB2) in terms of increasing the rigidity of the structural member 20C and increasing the connection strength between the top plate portion mold member 11C and the leg portion mold member 12C.

[0174] To elaborate on the above, as mentioned above, in the general use of the pallet, it is particularly useful to increase the section modulus in the cross section perpendicular to the contact surface FC1, and the section modulus is proportional to the square of the height (Z dimension) of the structural member 20C in the cross section. Here, the locking portion formed by combining the locking portion 40e and the locking portion 40g is formed so as to penetrate the top plate mold member 11C and the leg mold member 12C. In contrast, the locking portion formed by combining the locking portion 40b and the locking portion 40d in the second embodiment penetrates the top plate mold member 11B but does not penetrate the leg mold member 12B. Therefore, the locking portion formed by combining the locking portion 40e and the locking portion 40g has a larger height (Z dimension) in the cross section of the structural member 20C and a larger section modulus. That is, by providing the structural member 20C with the locking portion 40e and the locking portion 40g, it is possible to increase the resistance (rigidity) against deformation (deformation due to bending moment) of the pallet 1C in which a neutral plane is formed parallel to the contact surface FC1 more preferably than the pallet 1B according to the second embodiment, and at the same time, it is possible to preferably increase the resistance (strength) against external forces. Furthermore, it is possible to more preferably increase the joining strength between the top plate mold member 11C and the leg mold member 12C.

[0175] In addition, the portion of the locking portion formed by the locking portions 40e and 40g that intersects with the abutment surface FC1 is formed into a hollow cylindrical shape as described above. This shape contributes to weight reduction and cost reduction by reducing the volume of the structural member 20C, and also contributes to increasing the rigidity around the abutment surface FC.

[0176] [Locking part 40f] As described above, the locking portion 40f is formed integrally with the structural member 20C by a part of the polyurethane resin applied to the surface of the mold member 10C to form the structural member 20C entering the recess 30f provided in the top plate mold member 11C, more specifically, a through hole (see FIG. 34) defined by a pair of recesses 30f arranged on the side surface 11Cc of the adjacent top plate mold member 11C, and hardening the resin. The locking portion 40f is formed in a rectangular cylindrical shape complementary to the wall surface by covering the wall surface defining the recess 30f with the polyurethane resin, as shown in FIG. 27 to FIG. 29. The locking portion 40f is formed to bridge the structural member 20C forming the surface layer of the upper surface 1C-1a of the top plate 1C-1 and the structural member 20C forming the surface layer of the lower surface 1C-1b.

[0177] <Effects of Palette 1C> According to the pallet 1C of this embodiment having the above-mentioned configuration, in addition to the effects achieved by the pallet 1A of the first embodiment, the above-mentioned effects achieved by providing the locking portions 40e and 40g are achieved, i.e., the connection strength between the top plate mold member 11C and the leg mold member 12C, which are configured as separate bodies, is suitably improved, and further, the rigidity of the pallet 1C itself is improved through the structural member 20C, thereby improving the connection strength even more suitably than, for example, the pallet 1B of the second embodiment.

[0178] According to this embodiment, a predetermined mold member 10C is formed by combining a top plate mold member 11C and a leg mold member 12C, and a pallet 1C equipped with a structural member 20C is made by applying a polyurethane resin to the mold member 10C, etc., and the divided multiple top plate mold members 11C and leg mold members 12C function as the minimum unit that constitutes the pallet 1C. As a result, by simply preparing multiple top plate mold members 11C and multiple leg mold members 12C, pallets 1C of different sizes can be easily and inexpensively manufactured and provided.

[0179] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications are possible within the scope of the gist of the present invention. Furthermore, even if a configuration is not directly described in the specification and drawings, if the configuration has the same function and effect as the present invention, it is within the scope of the technical idea of ​​the present invention. Furthermore, the embodiments described above and shown in the drawings can be combined with each other as long as there is no contradiction in their purpose and configuration.

[0180] For example, the various different configurations shown in the first to third embodiments of components with common functions can be freely rearranged and / or combined as long as they are not contradictory. As an example, the second embodiment described above, which is configured to include a mixture of leg mold members 12B and leg mold members 12B', may be configured to include only leg mold members 12B or only leg mold members 12B'.

[0181] In addition, in the above-mentioned second embodiment, the configuration in which the locking portion 40a and the locking portion 40c form a pair to increase the connection strength between the top plate portion mold member 11B and one leg portion mold member 12B may be replaced with a configuration in which the locking portion 40a and the locking portion 40c form a pair and the locking portion 40b and the locking portion 40d are joined at the abutment surface FB1 to increase the connection strength.

[0182] Furthermore, in the second embodiment, the configuration in which the connection strength between the top plate mold member 11B and one leg mold member 12B' is increased by a pair of locking portions 40b and 40d may be replaced with a configuration in which two or more pairs of locking portions 40b and 40d are used. Similarly, in the third embodiment, the configuration in which the connection strength between the top plate mold member 11C and one leg mold member 12C is increased by a pair of locking portions 40e and 40g may be replaced with a configuration in which two or more pairs of locking portions 40e and 40g are used. Furthermore, a configuration in which a pair of locking portions 40b and 40d and a pair of locking portions 40e and 40g are mixed may be used.

[0183] Furthermore, as described above, the shape of the locking portion 40 (locking portions 40a, 40b, 40c, 40d, 40e, 40f, 40g) in the second and third embodiments may be appropriately changed to a shape having a larger section modulus in a predetermined cross-section, for example, a cross-section perpendicular and / or parallel to the contact surface between the top plate portion mold member 11 and the leg portion mold member 12, which are constructed as separate bodies, in order to improve the bonding strength of the top plate portion mold member 11 (top plate portion mold members 11B, 11C) and the leg portion mold member 12 (leg portion mold members 12B, 12B', 12C), which are constructed as separate bodies, and to more suitably increase the rigidity of the structural member 20 (structural members 20B, 20C). [Explanation of symbols]

[0184] 1A, 1B...three-dimensional structure (pallet, table), 1C...three-dimensional structure (pallet), 10A, 10B, 10C...molding members, 11A, 11B, 11C...top plate molding members, 12A, 12B, 12B', 12C...leg molding members, 20A, 20B, 20C...structural members, 30a, 30b, 30e, 30f...top plate recesses, 30c, 30d, 30g...leg recesses, 40a, 40b, 40e, 40f...top plate locking portions, 40c, 40d, 40g...leg locking portions, FA, FB, FB1, FB2, FC, FC1, FC2...contact surfaces, MS...reinforcing mesh sheet.

Claims

1. a plurality of mold members formed from a low density material; and a structural member formed of a polyurethane resin that covers the surface of the mold member. The plurality of mold members are connected to each other via their abutment surfaces, The structural member is a three-dimensional structure configured to cover the outer peripheral edge of the contact surface and most or substantially all of the surface of the mold member excluding the contact surface.

2. The three-dimensional structure according to claim 1, The three-dimensional structure, wherein the low-density material is polystyrene foam.

3. The three-dimensional structure according to claim 1 or 2, A three-dimensional structure in which a reinforcing mesh sheet is joined to a part or most of the surface of at least one of the mold members, excluding the contact surface.

4. The three-dimensional structure according to claim 1 or 2, Each of the plurality of mold members has at least one recess on a surface thereof, The structural member is a three-dimensional structure including an engaging portion formed of the polyurethane resin that covers at least a portion of a wall surface that defines the recess.

5. The three-dimensional structure according to claim 4, The engaging portion is a three-dimensional structure formed so that an area projected onto the contact surface is larger than an area projected onto a surface other than the contact surface.

6. The three-dimensional structure according to claim 4, At least two of the recesses communicate with each other at the contact surface, At least one of the at least two recesses communicating with each other on the contact surface has an opening on a surface other than the contact surface, A three-dimensional structure in which at least a portion of the engaging portion is formed to intersect with the contact surface.

7. The three-dimensional structure according to claim 6, At least one of the mold members has an internal void; the gap communicates with at least one of the at least two recesses that communicate with each other on the contact surface, A three-dimensional structure in which the area of ​​the void projected onto the contact surface is larger than the opening area of ​​the communicating recess on the contact surface.

8. The three-dimensional structure according to claim 1 or 2, The three-dimensional structure is a loading pallet or indoor or outdoor furniture.

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