Transport container

Abstract

To provide a conveyance container capable of ensuring favorable stacking and removal property while suppressing increase in cost.SOLUTION: A conveyance container of the present disclosure is made of resin and includes a bottom plate part, a side wall part extending upward from a peripheral part of the bottom plate part, four convex parts protruding downward at intervals from a lower surface of the bottom plate part so as to define two recessed parts intersecting with each other, and at least a pair of contact surfaces that are formed on the outer periphery of the lower surface of the bottom plate part so as to face each other via the four convex parts, each of the contact surfaces being capable of contacting an upper end surface of the side wall part of another conveyance container. The bottom plate part includes a thick wall part that overlaps a rectangle that contacts outer peripheral surfaces of the four convex parts when viewed from the vertical direction on an intersection side of the two recessed parts and is formed thicker than the area extending along the side wall part of the bottom plate part.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a transport container used to transport items. [Background technology]

[0002] A known example of this type of transport container is a bottomed box-shaped container made of resin having four lattice-shaped ribs (protrusions) spaced apart on the underside of the bottom plate to form a cross-shaped recess (see, for example, Patent Document 1). When multiple such transport containers are stacked, the four lattice-shaped ribs (protrusions) fit loosely into the opening of the lower transport container or into a recess formed in the lid of the lower transport container. This allows multiple transport containers to be stacked stably and allows the upper transport container to be easily removed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-137150 A (Fig. 3) Summary of the Invention [Problem to be solved by the invention]

[0004] If oil, such as rust-preventive oil, adheres to the items contained in the transport container, the oil also adheres to the upper surface of the bottom plate of the transport container. Furthermore, if multiple transport containers are stacked and oil is attached to the items in the lower transport container, the bottom plate (lower surface) of the upper transport container comes into contact with the oil vaporized in the lower transport container. Therefore, if oil is attached to the items in the transport container, the oil may penetrate the bottom plate, causing the bottom plate to deform (warp) so that the center of the bottom plate sinks. If the bottom plate deforms so that the center sinks, it becomes impossible to ensure clearance between at least a portion of the lattice-shaped rib portion of the upper transport container and the sidewall (inner surface) of the lower transport container. As a result, if the transport containers are deformed due to the influence of oil, multiple transport containers cannot be stacked stably, and the upper transport container may not be able to be removed from the lower transport container. On the other hand, if the transport containers are formed from a highly oil-resistant resin, such as a nylon-based resin, the occurrence of the above-mentioned bottom plate deformation may be suppressed. However, resins with high oil resistance are expensive, which increases the cost of the transport container.

[0005] Therefore, a main object of the present disclosure is to provide a transport container that can be easily stacked and easily removed while suppressing increases in cost. [Means for solving the problem]

[0006] The transport container of the present disclosure is a transport container formed from resin and including a bottom plate portion and a side wall portion extending upward from the peripheral portion of the bottom plate portion, and includes four convex portions protruding downward at a distance from the underside of the bottom plate portion so as to define two recesses that intersect with each other, and at least one pair of abutment surfaces formed on the outer periphery of the underside of the bottom plate portion so as to face each other via the four convex portions, and each of which can abut against the upper end surface of the side wall portion of another transport container, and the bottom plate portion includes a thick portion that overlaps, when viewed from above, a rectangle that contacts the outer periphery surfaces of the four convex portions on the intersection side of the two recesses and is formed thicker than the area extending along the side wall portion of the bottom plate portion.

[0007] The bottom plate portion of the transport container of the present disclosure includes four protrusions and at least one pair of abutment surfaces. The four protrusions protrude downward at a distance from the underside of the bottom plate portion to define two intersecting recesses. The pair of abutment surfaces is formed on the outer periphery of the underside of the bottom plate portion so as to face each other via the four protrusions, and each is capable of abutting against the upper end surface of the side wall portion of another transport container. Furthermore, the bottom plate portion of the transport container includes a thick-walled portion that overlaps in a vertical direction in a quadrangle that contacts the outer periphery of the four protrusions on the side of the intersection of the two recesses. The thick-walled portion is formed thicker than the region extending along the side wall portion of the bottom plate portion. As a result, in the transport container of the present disclosure, when oil penetrates the bottom plate portion, the intersection of the two recesses deforms the bottom plate portion so that the intersection of the two recesses rises upward, preventing each protrusion of the transport container from protruding outward. Therefore, when multiple transport containers are stacked, even if the bottom plate of the upper transport container is deformed by the influence of oil, it is possible to ensure sufficient clearance between each convex portion (outer peripheral surface) of the upper transport container and the side wall portion (inner surface) of the lower transport container that abuts against the abutting surface. Furthermore, the transport container of the present disclosure can reduce the adverse effects of oil adhering to items without using expensive resins with high oil resistance. As a result, the transport container of the present disclosure can ensure good stackability and ease of removal while suppressing cost increases. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a transport container of the present disclosure. [Figure 2] FIG. 1 is a perspective view of a transport container of the present disclosure. [Figure 3] FIG. 2 is an enlarged partial cross-sectional view of a shipping container of the present disclosure. [Figure 4] FIG. 10 is an enlarged partial cross-sectional view showing a conventional transport container. [Figure 5] FIG. 10 is an explanatory diagram showing the results of an analysis of a conventional transport container. [Figure 6] FIG. 10 is an explanatory diagram showing the results of an analysis of a conventional transport container. [Figure 7] 1 is an explanatory diagram showing a transport container according to the present disclosure. [Figure 8]FIG. 2 is an enlarged partial cross-sectional view of a shipping container of the present disclosure. [Figure 9] 10A and 10B are cross-sectional views showing modified thick-walled portions provided on the bottom plate portion of the transport container of the present disclosure. [Figure 10] 10 is a cross-sectional view showing another modified embodiment of a thick portion provided on the bottom plate portion of the transport container according to the present disclosure. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Next, embodiments of the present disclosure will be described with reference to the drawings.

[0010] 1 and 2 are perspective views of a transport container 1 according to the present disclosure. The transport container 1 shown in these drawings is transported and stored with articles housed inside. The transport container 1 is integrally molded by injection molding of a polypropylene resin into a bottomed, square-tube shape, i.e., a cube (rectangular parallelepiped) with an open top. As shown in the figures, the transport container 1 includes a bottom plate 2 having a rounded square (rounded rectangular) planar shape and a square-tube side wall 3 extending upward from the periphery of the bottom plate 2. The side wall 3 has four side surfaces 4, and curved corner surfaces are formed between adjacent side surfaces 4. Furthermore, the side wall 3 includes flanges 3f that protrude outward from the upper edges (peripheries on the opening end side) of each side surface 4 and each corner surface and form the upper end surface of the side wall 3.

[0011] As shown in FIG. 2 , each transfer container 1 includes four rib portions (protrusions) 5 and a pair of contact surfaces 6 formed on the bottom plate 2. In this embodiment, each rib portion 5 is a lattice-like rib portion including a cylindrical portion having a cross-sectional shape of a rounded square (rounded rectangle) and lattice-like ribs formed within the cylindrical portion. The four rib portions 5 protrude downward from the lower surface of the bottom plate 2 at intervals so as to be adjacent to corresponding corners of the lower surface of the bottom plate 2. As a result, the four rib portions 5 define two recesses 7 that cross (orthogonally intersect) each other in a crisscross pattern at the center of the bottom plate 2. The pair of contact surfaces 6 are formed on the outer periphery of the lower surface of the bottom plate 2 so as to face each other via the four rib portions 5. Each of the pair of contact surfaces 6 can contact the upper end surface of the side wall 3 of another transfer container 1, i.e., the upper surface of the flange portion 3f. Two pairs of contact surfaces 6 may be provided for the four rib portions 5, or the contact surface 6 may be formed around the entire outer periphery of the lower surface of the bottom plate portion 2.

[0012] When such transfer containers 1 are stacked in multiple tiers, the four rib portions 5 of the transfer container 1 are loosely fitted into the opening of the lower transfer container 1 (side wall portion 3) or into the recess of the lid attached to the lower transfer container 1. That is, the specifications of the four rib portions 5 are determined so that, when the flange portion 3f of the side wall portion 3 of the lower transfer container 1 abuts against the corresponding abutment surface 6 of the upper transfer container 1, as shown in Fig. 3, a clearance C is formed between the outer peripheral surface of each rib portion 5 and the inner surface of the side wall portion 3. This makes it possible to stably stack multiple transfer containers 1 and to easily remove the upper transfer container 1.

[0013] Furthermore, two adjacent rib portions 5 of the transport container 1 can also be loosely fitted into the opening of another transport container (side wall portion) having a width approximately half the width of the transport container 1. Therefore, the transport container 1 can also be mounted on two of the other transport containers. Furthermore, if two rib portions (convex portions) aligned in the longitudinal direction are formed on the bottom plate portion of the other transport container, the two other transport containers can be mounted on the transport container 1. For this reason, the width of each recess 7 in the transport container 1 is set to be longer than twice the width of the flange portion formed on the side wall portion of the other transport container.

[0014] Here, the items loaded on the bottom plate 2 of the transfer container 1 include parts coated with or filled with anti-rust oil, lubricating oil, etc., and if anti-rust oil or other oil is attached to the items contained in the transfer container 1, a large amount of oil may adhere to the upper surface of the bottom plate 2 of the transfer container 1. Furthermore, if multiple transfer containers 1 are stacked and oil is attached to an item contained in a lower transfer container 1, the bottom plate 2 of the upper transfer container 1 will come into contact with the oil that has vaporized in the lower transfer container 1.

[0015] Therefore, if oil is present on an item in a conventional transfer container 1' containing multiple lattice-shaped ribs 5', the oil may penetrate the bottom plate 2', causing the bottom plate 2' of the transfer container 1' to deform (warp) so that the center of the bottom plate 2' (the intersection of two recesses 7', see FIG. 5) sinks, as shown in FIG. 4. When the bottom plate 2' deforms so that the center sinks, as can be seen in FIG. 4, each lattice-shaped rib 5' protrudes outward, making it impossible to ensure clearance between at least a portion of the outer periphery of the multiple lattice-shaped ribs 5' and the sidewall 3' (inner surface) of the lower transfer container 1'. As a result, if the transfer container 1', i.e., the bottom plate 2', deforms due to the oil, multiple transfer containers 1' cannot be stacked stably, and the upper transfer container 1' may not be able to be removed from the lower transfer container 1'.

[0016] In light of this phenomenon, the inventors conducted extensive research to further improve the handleability of a transport container 1 for storing oily articles. The inventors first conducted an experiment on a conventional transport container 1', which included a bottom plate 2' with a flat upper surface and multiple lattice-like ribs 5', in which loads were applied from above and below the bottom plate 2'. As a result, they found that the elastic modulus when a downward load was applied to the center of the upper surface of the bottom plate 2' (the intersection of two recesses 7') was lower than the elastic modulus when an upward load was applied to the center of the lower surface of the bottom plate 2'. In other words, it was found that the conventional transport container 1' has a characteristic in which the bottom plate 2' with a flat upper surface is prone to deformation, causing the center to sink. Furthermore, considering the deformation of the bottom plate 2' due to oil penetration in a conventional transport container 1', it is assumed that oil penetrates the entire bottom plate 2', causing the entire bottom plate 2' to swell uniformly. For this reason, it is believed that the bottom plate portion 2' of the conventional transfer container 1' is deformed so that the center portion sinks due to its own weight.

[0017] Furthermore, the inventors evaluated the degree of influence of oil, the weight of the article, etc. on the deformation of the bottom plate portion 2' by placing the transport container 1' in a thermostatic bath (for example, in an environment of 80°C) for a predetermined time (for example, 6 days) under a plurality of evaluation conditions. (1) A transport container 1' with the top surface of the bottom plate 2' soaked in oil (rust-preventive oil), (2) A transport container 1' with a weight (for example, about 15 kg) placed on the top surface of the bottom plate portion 2'; (3) The top surface of the bottom plate 2' is soaked in oil (rust-preventive oil) and a weight (for example, about 15 kg) is placed on the transport container 1'. (4) A transport container 1' stacked on top of a transport container 1' whose top surface is soaked in oil (rust-preventive oil) on the bottom plate 2' It was.

[0018] These experiments revealed that in a conventional transport container 1', oil penetration had a greater effect on the deformation of the bottom plate 2' in the direction of sinking of the center than the weight of the items. Figure 5 shows the distribution of downward deformation of the bottom plate 2' in a transport container 1' with oil (rust prevention oil) soaked on the top surface of the bottom plate 2'. In the first distribution area A1, the darkest shaded area in Figure 5, the downward deformation of the bottom plate 2' was 16.0-14.0 mm. In the second distribution area A2, the second darkest shaded area, the downward deformation of the bottom plate 2' was 14.0-9.0 mm. In the third distribution area A3, the third darkest shaded area, the downward deformation of the bottom plate 2' was 9.0-4.5 mm. In the fourth distribution area A4, the lightest shaded area, the downward deformation of the bottom plate 2' was 4.5-2.5 mm. Furthermore, in a transport container 1' that has the top surface of the bottom plate portion 2' immersed in oil (rust-preventive oil) and placed in a constant temperature bath (e.g., in an environment of 80°C) for a predetermined period of time (e.g., 6 days), the deformation of the bottom plate portion 2' causes the center portion to sink, and the average value of the widths L1 and L2 (= L1) of two adjacent rib portions 5 out of the four rib portions 5 that fit loosely into the opening of the lower transport container 1 becomes larger than the value before immersion in oil (293.00 to 293.5 mm), becoming a value (300.3 mm) that exceeds the allowable value (the distance between an opening between a pair of side wall portions 3, etc.; in this case, 300 mm).

[0019] 6, when the transfer container 1' is viewed from above, the first distribution region A1 is contained within a first rectangle S1 (a square in this embodiment) that contacts the outer periphery of the four lattice-shaped ribs 5' at the intersection of the two recesses 7', i.e., at the center of the bottom plate 2', the circumscribing circle OC of the first rectangle S1, and the circumscribing rectangle SO (a square in this embodiment) of the circumscribing circle OC. Furthermore, when the transfer container 1' is viewed from above, the first to fourth distribution regions A1-A4 are contained within a second rectangle S2 (a square in this embodiment) formed by the diagonals of the four lattice-shaped ribs 5', and are generally contained within a third rectangle S3 (a square in this embodiment) that is formed by rotating the second rectangle S2 by 45° and oriented in the same direction as the circumscribing rectangle SO of the circumscribing circle OC.

[0020] Based on these experimental and analytical results, the inventors decided to form a thick portion (convex portion) 20 on the bottom plate 2 of the transfer container 1 of the present disclosure so as to overlap at least the first rectangle S1 in a vertical view, as shown in FIG. 7 . The thick portion 20 overlaps the inscribed circle IC (the area surrounded by the circumference) in a vertical view and is thicker than a region 21 extending along the side wall 3 of the bottom plate 2. More specifically, the thick portion 20 has an outer periphery that overlaps the circumference of the inscribed circle IC in a vertical view, and a convexly curved upper surface that rises upward from the outer periphery toward the center of the first rectangle S1, the circumscribed circle OC, and the circumscribed rectangle SO. As a result, the thickness of the thick portion 20 gradually increases from the outer periphery toward the center, and the upper surface of the thick portion 20 protrudes upward from the upper surface of the region 21. In the transfer container 1 shown in FIG. 7, the height h from the region 21 to the top of the thick-walled portion 20 is approximately 5 mm.

[0021] The inventors then fabricated several prototypes of the transport container 1 and placed the transport container 1 in a thermostatic chamber (for example, in an 80°C environment) for a predetermined period of time (for example, six days) under the evaluation conditions (1) to (4) above to evaluate the degree of influence of oil, the weight of the object, etc. on the deformation of the bottom plate portion 2. As a result, it was found that in the transport container 1 shown in Fig. 7, when oil adhering to the upper surface of the bottom plate portion 2 penetrates into the bottom plate portion 2, the bottom plate portion 2 deforms (warps) so that the center of the bottom plate portion 2, i.e., the intersection of the two recesses 7, bulges upward, as shown in Fig. 8. The following factors (1) to (4) are thought to be the causes of this phenomenon. (1) Oil that comes into direct contact with the upper surface of the bottom plate portion 2 penetrates into the bottom plate portion 2 faster than vaporized oil that comes into contact with the lower surface of the bottom plate portion 2, and swelling of the upper surface area of ​​the bottom plate portion 2 progresses faster than swelling of the lower surface area of ​​the bottom plate portion 2. (2) By making the upper surface of the thick-walled portion 20 protrude upward from the upper surface of the region 21, the surface area of ​​the upper surface of the thick-walled portion 20 is increased, and the contact area with oil is also increased, so that swelling of the upper surface area of ​​the bottom plate portion 2 progresses more quickly than in the bottom plate portion 2' of a conventional transport container 1'. (3) As the oil penetrates, swelling progresses along the upper surface of the convexly curved thick portion 20, making the bottom plate portion 2 more likely to deform (warp) so that the center portion bulges upward. (4) The modulus of elasticity of the bottom plate portion 2 becomes high when a downward load is applied to the center of the upper surface of the bottom plate portion 2.

[0022] As a result, when oil penetrates the bottom plate 2 of the transfer container 1, the bottom plate 2 is deformed so that the center of the bottom plate 2 bulges upward, preventing the ribs 5 from protruding outward, as shown in FIG. 8 . Therefore, even if an upper transfer container 1 (bottom plate 2) is deformed due to oil adhering to an object when multiple transfer containers 1 are stacked, sufficient clearance C can be maintained between the outer surface of each rib 5 of the upper transfer container 1 and the inner surface of the side wall 3 of the lower transfer container 1 abutting against the contact surface 6 or the inner surface of the lid attached to the lower transfer container 1. Furthermore, the transfer container 1 can reduce the adverse effects of oil adhering to an object without using expensive resins such as nylon-based resins with high oil resistance. As a result, the transfer container 1 can ensure good stackability and ease of removal while suppressing cost increases.

[0023] Furthermore, in the transfer container 1, the thick-walled portion 20 is formed on the bottom plate portion 2 so as to overlap, when viewed from the top and bottom, with the inscribed circle IC of the second quadrangle S2 formed by the diagonals of the four rib portions 5. This makes it possible to effectively prevent the bottom plate portion 2 from being deformed by the influence of oil, such that the intersection (center) of the two recessed portions 7 sinks.

[0024] Furthermore, in the transport container 1, the thick-walled portion 20 may be formed on the bottom plate 2 of the transport container 1 so as to be included inside (including on the outer periphery of) a third rectangle S3 that is oriented in the same direction as a circumscribed rectangle SO that circumscribes the circumscribed circle OC of the first rectangle S1 by rotating the second rectangle S2 formed by the diagonals of the four rib portions 5 by 45° when viewed from the top-bottom direction. In other words, the outer periphery of the thick-walled portion 20 may overlap the outer periphery of the third rectangle S3 when viewed from the top-bottom direction. This makes it possible to form the thick-walled portion 20 on the bottom plate 2 while effectively reducing the impact on the loadability of items, etc.

[0025] Furthermore, the transport container 1, i.e., the bottom plate 2 and side wall 3 including the plurality of ribs 5, are integrally formed from a polypropylene-based resin. This effectively prevents increases in the cost of the transport container 1. However, the transport container 1 may be formed from a resin other than a polypropylene-based resin, such as a polyolefin-based resin. The transport container 1 may also be formed from recycled materials of other polyolefin-based resins.

[0026] Furthermore, in a transport container 1 including a bottom plate portion 2 on which a thick portion 20 is formed, it is possible to suppress downward deformation of the bottom plate portion 2 (in the direction in which the center portion sinks) due to the weight of an item inside the transport container 1. Furthermore, in a transport container 1 including a bottom plate portion 2 on which a thick portion 20 is formed, it is possible to suppress downward deformation of the bottom plate portion 2 (in the direction in which the center portion sinks) even if a high-temperature item is stored in the transport container 1.

[0027] The bottom plate 2 of the transfer container 1 may include a thick portion 20B as shown in FIG. 9. The thick portion 20B shown in FIG. 9 includes an outer periphery that overlaps the circumference of the inscribed circle IC or the outer periphery of the third rectangle S3 when viewed from above; a flat portion that overlaps the circumscribed circle OC or the circumscribed rectangle SO when viewed from above and has a uniform (same) thickness that is thicker than the region 21; and an inclined portion whose thickness gradually increases from the outer periphery toward the flat portion. That is, the thick portion 20B has a truncated cone-shaped or truncated pyramid-shaped upper surface that protrudes upward from the upper surface of the region 21. Even in a transfer container 1 with such a thick portion 20B formed in the bottom plate 2, when oil penetrates the bottom plate 2, the bottom plate 2 can be deformed so that the center, i.e., the intersection of the two recesses 7, rises upward.

[0028] 10, the bottom plate 2 of the transfer container 1 may include a thick portion 20C. The thick portion 20C shown in the figure has an outer periphery that overlaps the circumference of the inscribed circle IC or the outer periphery of the third rectangle S3 when viewed from the top-bottom direction, and is formed so that the entire inside of the outer periphery has a uniform (same) thickness that is thicker than the region 21. Even in a transfer container 1 having such a thick portion 20C formed in the bottom plate 2, when oil penetrates the bottom plate 2, it is possible to deform the bottom plate 2 so that the center, i.e., the intersection of the two recesses 7, rises upward. According to the evaluations of the inventors, when the upper surface of the transport container 1 including the thick-walled portion 20C having an outer periphery that overlaps the outer periphery of the third rectangle S3 when viewed from the top and bottom directions is immersed in oil (rust-preventive oil) and placed in a constant temperature bath (for example, in an environment of 80°C) for a predetermined period of time (for example, 6 days), the bottom plate portion 2 is deformed in a direction such that the central portion bulges upward, and the average value of the widths L1 and L2 (= L1) of two adjacent rib portions 5 out of the four rib portions 5 that fit loosely into the opening of the lower transport container 1 becomes larger than the value before immersion in oil (293.00 to 293.5 mm), but does not exceed the allowable value (300 mm), and the average value of the widths L1 and L2 is approximately 298 mm. Furthermore, according to the evaluations of the inventors, even when the upper surface of the transport container 1 including the thick-walled portion 20C having an outer periphery that overlaps the outer periphery of the circumscribed rectangle SO when viewed from the top and bottom is immersed in oil and placed in a constant temperature bath (for example, in an environment of 80°C) for a predetermined period of time (for example, 6 days), the average value of the widths L1 and L2 (= L1) of two adjacent rib portions 5 out of the four rib portions 5 that are loosely fitted into the opening of the lower transport container 1, etc., is kept below the allowable value (300 mm).

[0029] Furthermore, in the above-mentioned transfer container 1, the rib portion 5 is not limited to having lattice-shaped ribs, and may have ribs other than lattice-shaped ribs, for example, honeycomb-shaped ribs. Furthermore, the transfer container 1 may include, instead of the rib portion 5, a convex portion that protrudes downward from the lower surface of the bottom plate portion 2 to form a concave portion on the upper surface side of the bottom plate portion 2 and has a flat lower surface without ribs. Furthermore, the transfer container 1 is not limited to having four rib portions 5, and may include, for example, an even number of rib portions 5 (convex portions), six or more. In this case, the bottom plate portion 2 may have a plurality of thick portions provided for each of the four rib portions (convex portions) that define two concave portions, or only one thick portion may be provided for the bottom plate portion 2 so as to encompass all of the first rectangles defined by the four rib portions (convex portions) that define two concave portions.

[0030] As described above, the transport container of the present disclosure is a transport container (1) formed of resin and including a bottom plate portion (2) and a side wall portion (3) extending upward from the peripheral edge of the bottom plate portion (2), and includes four convex portions (5) protruding downward from the lower surface of the bottom plate portion (2) at intervals so as to define two recesses (7) that intersect with each other, and four convex portions (5) formed on the outer periphery of the lower surface of the bottom plate portion (2) so as to face each other across the four convex portions (5), Each of the containers includes at least one pair of abutment surfaces (6) that can abut against the upper end surface (3f) of the side wall portion (3) of another of the transport containers (1), and the bottom plate portion (2) includes thick-walled portions (20, 20B, 20C) that overlap, when viewed from above, a rectangle (S1) that contacts the outer peripheral surfaces of the four protrusions (5) on the intersection side of the two recesses (7) and are formed thicker than the region (21) extending along the side wall portion (3) of the bottom plate portion (2).

[0031] The bottom plate portion of the transport container of the present disclosure includes four protrusions and at least one pair of abutment surfaces. The four protrusions protrude downward at a distance from the underside of the bottom plate portion to define two intersecting recesses. The pair of abutment surfaces is formed on the outer periphery of the underside of the bottom plate portion so as to face each other via the four protrusions, and each is capable of abutting against the upper end surface of the side wall portion of another transport container. Furthermore, the bottom plate portion of the transport container includes a thick-walled portion that overlaps in a vertical direction in a quadrangle that contacts the outer periphery of the four protrusions on the side of the intersection of the two recesses. The thick-walled portion is formed thicker than the region extending along the side wall portion of the bottom plate portion. As a result, in the transport container of the present disclosure, when oil penetrates the bottom plate portion, the intersection of the two recesses deforms the bottom plate portion so that the intersection of the two recesses rises upward, preventing each protrusion of the transport container from protruding outward. Therefore, when multiple transport containers are stacked, even if the bottom plate of the upper transport container is deformed by the influence of oil, it is possible to ensure sufficient clearance between each convex portion (outer peripheral surface) of the upper transport container and the side wall portion (inner surface) of the lower transport container that abuts against the abutting surface. Furthermore, the transport container of the present disclosure can reduce the adverse effects of oil adhering to items without using expensive resins with high oil resistance. As a result, the transport container of the present disclosure can ensure good stackability and ease of removal while suppressing cost increases.

[0032] Furthermore, the convex portions (5) may be lattice-shaped rib portions having a cross-sectional shape of a rounded rectangle, and the thick portions (20, 20B, 20C) may be formed on the bottom plate portion (2) so as to overlap the inscribed circle (IC) of a second quadrangle (S2) formed by the diagonals of the four convex portions (5) when viewed from the top-bottom direction.

[0033] This makes it possible to effectively prevent the bottom plate portion from being deformed by the influence of oil so that the intersection of the two recesses sinks.

[0034] The thick portions (20, 20B, 20C) may be formed on the bottom plate portion (2) so that, when viewed from the top-bottom direction, the second rectangle (S2) formed by the diagonals of the four protrusions (5) is rotated to be included inside a third rectangle (S3) aligned with a circumscribing rectangle (SO) circumscribing the circumscribing circle (OC) of the rectangle (S1).

[0035] This makes it possible to form a thick portion in the bottom plate portion while effectively reducing the influence on the ability to mount articles, etc.

[0036] The thick-walled portions (20, 20B) may be formed so that the thickness gradually increases from the outer periphery toward the center.

[0037] The thick portion (20C) may have a uniform thickness.

[0038] The upper surfaces of the thick portions (20, 20B, 20C) may protrude upward from the upper surface of the region (21) extending along the side wall portion (3) of the bottom plate portion (2).

[0039] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present disclosure. Furthermore, the above-described embodiment is merely a specific form of the invention described in the Summary of the Invention, and does not limit the elements of the invention described in the Summary of the Invention. [Industrial Applicability]

[0040] The invention of the present disclosure can be used in the transport container manufacturing industry and the like. [Explanation of symbols]

[0041] 1 transport container, 2 bottom plate portion, 20, 20B, 20C thick portions, 21 area, 3 side wall portion, 3f flange portion, 5 rib portion, 6 abutment surface, 7 recess, C clearance, S1 first rectangle, S2 second rectangle, S3 third rectangle, SO circumscribed rectangle, IC inscribed circle, OC circumscribed circle.

Claims

1. A transport container made of resin and including a bottom plate portion and a side wall portion extending upward from a peripheral edge portion of the bottom plate portion, at least four projections projecting downwardly at intervals from the lower surface of the base plate portion so as to define two recesses intersecting each other; at least one pair of contact surfaces formed on the outer periphery of the lower surface of the bottom plate portion so as to face each other via the respective convex portions, the contact surfaces being capable of contacting the upper end surfaces of the side wall portions of the other transport containers, the bottom plate portion includes, at all intersections of two recesses defined by the four adjacent protrusions, thick portions that overlap so as to encompass a quadrangle that contacts the outer peripheral surfaces of the four protrusions when viewed from the top-bottom direction, and that are formed thicker than a region extending along the side wall portion of the bottom plate portion; The transport container has an upper surface of the thick portion that protrudes upward from an upper surface of the region that extends along the side wall portion of the bottom plate portion.

2. 2. The transport container according to claim 1, The transport container, wherein the convex portion is a lattice-shaped rib portion having a cross section of a rounded rectangular shape.

3. In the transport container according to claim 2, The thick-walled portion is formed on the bottom plate portion so as to overlap the inscribed circle of a second rectangle formed by the diagonals of the four protrusions when viewed from the top-bottom direction.

4. 2. The transport container according to claim 1, The thick-walled portion is a transport container formed on the bottom plate portion so that, when viewed from the top-bottom direction, it is included inside a third rectangle formed by rotating a second rectangle formed by the diagonals of the four protrusions and aligning its orientation with a circumscribing rectangle that circumscribes the circumscribing circle of the second rectangle.

5. 2. The transport container according to claim 1, The thick-walled portion is formed so that the thickness gradually increases from the outer periphery toward the center.

6. 2. The transport container according to claim 1, The thick-walled portion is a transport container having a uniform thickness.

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