Carriage

Abstract

To provide a carriage (a stacking carriage) that has a stability even if being stacked.SOLUTION: A stacking carriage 200 according to the present invention includes multiple carriages 100 stacked one another. The carriage 100 includes a carriage main body 10 and casters 30 attached at four corners, respectively, of a lower surface 14. Provided in an upper surface 11 of the carriage main body 10 at positions corresponding to the four corners, respectively, are caster placing recesses 20 where the respective casters 30 of the other carriage are placed. Engagement recesses 25 are provided in the upper surface 11 of the carriage main body 10, and engagement protrusions 26 are provided on the lower surface 14 of the carriage main body 10. In a structure in which the two carriage main bodies 10 are stacked with each other, each engagement protrusion 26 is fitted in each engagement recess 26, and a clearance S is provided between a lower end 30b of each caster 30 of the carriage main body 10 placed at the upper side and an upper surface 20t of each caster placing recess 20.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a trolley, and more particularly to a vertically stackable trolley. [Background technology]

[0002] When transporting luggage, it is very convenient to use a dolly (transport dolly). A dolly usually has casters attached to the bottom of a wooden board, and the casters allow the luggage placed on the dolly board to be transported smoothly. In factories, multiple dollies are often used. When dollies are not in use, it is desirable to stack them together for storage, but stacking them makes them unstable and the protruding casters get in the way, often wasting storage space.

[0003] Some dollies can be stacked vertically (see, for example, Patent Document 1). FIG. 12 shows a dolly (stack type dolly) 1000 disclosed in Patent Document 1. The dolly 1000 shown in FIG. 12 has a structure in which wheels (casters) 130 are attached under a loading platform 110. A groove portion (wheel storage portion) 120 is provided on the upper surface of the loading platform 110. This structure allows a plurality of dollies 1000 to be stacked. Specifically, when a second (upper) dolly 1000 is placed on the loading platform 110 of a first (lower) dolly 1000, the wheels 130 of the second (upper) dolly 1000 can be stored in the groove portion (wheel storage portion) 120 of the first (lower) dolly 1000. In this manner, a plurality of dollies 1000 can be stacked. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-190110 A Summary of the Invention [Problem to be solved by the invention]

[0005] The inventor of the present invention has been thinking about how to store dollies (transport dollies) day by day. A dolly is useful because it has wheels (casters). Since the smooth rotation of the casters makes it easy to transport luggage, it is natural that stacking casters will make the dolly unstable. Although there are casters with brakes, it is not practical to turn the brakes on and off every time, which is time-consuming.

[0006] In the dolly 1000 shown in Fig. 12, the wheels 130 of the second (upper) dolly 1000 are stored in the grooves (wheel storage sections) 120 of the first (lower) dolly 1000, but since the wheels 130 of the second (upper) dolly 1000 come into contact with the loading platform 110 (groove sections 120) of the first (lower) dolly, in reality the dolly is wobbly and unstable. If two dollies 1000 are stacked, some wobbling is tolerable, but stacking five or more dollies 1000, especially ten or more dollies 1000, is difficult due to the influence of wheel wobbling, and such a stacked state is dangerous because it is unstable.

[0007] As a result of intensive research conducted in the course of such investigations, the inventors of the present application came up with the idea of ​​a cart with a new structure using a new approach (a stackable cart, a stacking cart), which led to the present invention.

[0008] The present invention has been made in consideration of the above points, and a main object of the present invention is to provide a cart (stacking cart) that is stable even when stacked. [Means for solving the problem]

[0009] The stacking trolley according to the present invention is a stack of trolleys, and the trolley comprises a trolley main body and casters attached to the four corners of the underside of the trolley main body. The upper surface of the trolley main body is provided with caster storage recesses at positions corresponding to the four corners for storing the casters attached to the underside of the trolley main body part arranged in the upper tier. The upper surface of the trolley main body is provided with a fitting recess. The lower surface of the trolley main body part arranged in the upper tier is provided with a fitting protrusion. In a structure in which the trolley main body part and the trolley main body part arranged in the upper tier are stacked, the fitting protrusion of the trolley main body part arranged in the upper tier is inserted into the fitting recess of the trolley main body part, and a gap is generated between the lower end of the caster of the trolley main body part arranged in the upper tier and the upper surface of the caster storage recess of the trolley main body part.

[0010] In a preferred embodiment, the stacking cart has a structure of at least four stacked cars, each of the at least four cars having an identical structure.

[0011] In a preferred embodiment, the upper surface of the dolly body is a loading platform surface on which luggage is placed, and the dolly body has a rectangular shape when viewed from above. A handle is provided on each of the four sides of the rectangle.

[0012] In a preferred embodiment, the handle is formed by a through hole formed in an outer edge of the cart body.

[0013] In a preferred embodiment, the fitting recess and the fitting protrusion have an L-shape that fits into each other. Four combinations of the fitting recess and the fitting protrusion are formed on one cart body.

[0014] In a preferred embodiment, the cart body is formed by blow molding, and a connection recess is formed in the cart body to connect the upper surface and the lower surface of the cart body. A plurality of insertion marks of blow needles during blow molding are formed in the lower surface of the cart body.

[0015] In a preferred embodiment, the cart body has a symmetrical structure when viewed from above. The cart body has a hollow structure. An error in the distance between the upper surface and the lower surface of the cart body is 0.5 mm or less.

[0016] The stackable trolley according to the present invention comprises a trolley main body and casters attached to the four corners of the underside of the trolley main body. The upper surface of the trolley main body is provided with caster storage recesses at positions corresponding to the four corners for storing casters of another trolley to be stacked on the trolley main body. The upper surface of the trolley main body is provided with a fitting recess. The lower surface of the trolley main body is provided with a fitting protrusion having a shape that can fit into the fitting recess. In a structure in which the trolley and the other trolley to be stacked on top of it are stacked, the fitting protrusion of the other trolley is inserted into the fitting recess of the trolley, and a gap is generated between the lower ends of the casters of the other trolley and the upper surface of the caster storage recess of the trolley.

[0017] In a preferred embodiment, the upper surface of the dolly body is a loading platform surface on which luggage is placed, and the dolly body has a rectangular shape when viewed from above. A handle is provided on each of the four sides of the rectangle. The mating recess and the mating protrusion are L-shaped. Four combinations of the mating recess and the mating protrusion are formed on one dolly body.

[0018] In a preferred embodiment, the cart body is formed by blow molding. A connection recess is formed in the cart body, connecting the upper surface and the lower surface of the cart body. A plurality of insertion marks of blow needles during blow molding are formed in the lower surface of the cart body. The cart body has a symmetrical structure when viewed from above. The cart body has a hollow structure. An error in the distance between the upper surface and the lower surface of the cart body is 0.5 mm or less.

[0019] In a preferred embodiment, the cart has a structure that allows it to stand on its own on a horizontal ground surface at a side surface between an upper surface and a lower surface of the cart body.

[0020] Another stacking trolley according to the present invention is a stack of trolleys, the trolley comprising a trolley body and casters attached to the four corners of the underside of the trolley body. The upper surface of the trolley body is provided with a caster storage recess for storing the caster attached to the underside of the trolley body part arranged in the upper tier at a position corresponding to the four corners. The upper surface of the trolley body is provided with a fitting recess. The lower surface of the trolley body part arranged in the upper tier is provided with a fitting protrusion. In a structure in which the trolley body part and the trolley body part arranged in the upper tier are stacked, the fitting protrusion of the trolley body part arranged in the upper tier is inserted into the fitting recess of the trolley body part, and there is zero clearance between the lower end of the caster of the trolley body part arranged in the upper tier and the upper surface of the caster storage recess of the trolley body part.

[0021] Another trolley according to the present invention is a stackable trolley, comprising a trolley main body and casters attached to the four corners of a lower surface of the trolley main body. The upper surface of the trolley main body is provided with caster storage recesses at positions corresponding to the four corners for storing casters of another trolley to be stacked on the trolley main body. The upper surface of the trolley main body is provided with a fitting recess. The lower surface of the trolley main body is provided with a fitting protrusion having a shape that can fit into the fitting recess. In a structure in which the trolley and the other trolley to be stacked on top of it are stacked, the fitting protrusion of the other trolley is inserted into the fitting recess of the trolley, and there is zero gap between the lower ends of the casters of the other trolley and the upper surface of the caster storage recess of the trolley.

[0022] In a preferred embodiment, the cart has a structure that allows it to stand on its own on a horizontal ground surface at a side surface between an upper surface and a lower surface of the cart body.

[0023] The method for manufacturing a stackable dolly according to the present invention includes a step of forming a dolly body by blow molding using a mold, and a step of attaching casters to the underside of the dolly body. In the step of forming the dolly body, the mold has a portion corresponding to a caster storage recess located on the upper surface of the dolly body, a portion corresponding to a fitting recess located on the upper surface of the dolly body, and a portion corresponding to a fitting protrusion located on the lower surface of the dolly body. In the glow molding, the temperature of the mold is adjusted so that the error in the distance between the upper surface and the lower surface of the dolly body to be formed is 0.5 mm or less. Effect of the Invention

[0024] According to the stacking dolly of the present invention, the upper surface of the dolly body part to which casters are attached at the four corners is provided with a caster storage recess for storing the caster of the dolly body part arranged in the upper stage, and in a structure in which the dolly body parts are stacked, the fitting protrusion of the dolly body part of the upper stage is inserted into the fitting recess of the dolly body part, and a gap is generated between the lower end of the caster of the dolly body part of the upper stage and the upper surface of the caster storage recess. As a result, even when the dolly body parts are stacked, the lower end of the caster of the upper stage does not contact the dolly body part (dolly) below it, so that the dolly body parts can be stacked stably without rattling, and it is also possible to stack five or more dollies (particularly ten or more dollies). As a result, according to the present invention, a dolly (stacking dolly) that is stable even when stacked can be realized. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a perspective view showing a configuration of a cart 100 according to an embodiment of the present invention. [Diagram 2] 1 is a perspective view (perspective view from the top) showing a configuration of a stacking cart 200 according to an embodiment of the present invention. [Diagram 3] 1 is a perspective view (perspective view from the bottom side) showing a configuration of a stacking cart 200 according to an embodiment of the present invention. [Figure 4] FIG. 2 is a top view (plan view) showing the configuration of the cart 100 according to the present embodiment. [Diagram 5] 2 is a bottom view (a bottom plan view) showing the configuration of the cart 100 according to the present embodiment. FIG. [Figure 6] 1 is a side view (long side view) showing the configuration of a cart 100 according to the present embodiment. [Figure 7] 1 is a side view (short side view) showing the configuration of a cart 100 according to the present embodiment. [Figure 8] FIG. 1 is a perspective view showing a state in which stacking carts 200 of this embodiment are stacked in multiple stages (five or more stages). [Figure 9] FIG. 2 is a diagram showing a state in which the side of the cart 100 of this embodiment is placed on the ground and stands independently. [Figure 10]1(a) to 1(c) are process diagrams illustrating a manufacturing process of the carriage body 10 according to the embodiment of the present invention. [Figure 11] 1(a) to 1(c) are process diagrams illustrating a manufacturing process of the carriage body 10 according to the embodiment of the present invention. [Figure 12] FIG. 1 is a perspective view showing the configuration of a conventional cart 1000. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. In the following drawings, for the sake of simplicity, the same reference numerals are used for components and parts that perform the same function, and duplicated descriptions may be omitted or simplified. In addition, the dimensional relationships (length, width, thickness, etc.) in each drawing are basically set to the dimensional relationships, so that it is possible to extract six-sided views from the drawings, but they may not necessarily accurately reflect the actual dimensional relationships.

[0027] Furthermore, matters other than those specifically mentioned in this specification that are necessary for carrying out the present invention can be understood as design matters for a person skilled in the art based on the prior art in the field. The present invention can be carried out based on the contents disclosed in this specification and drawings and the technical common sense in the field. In addition, the present invention is not limited to the following embodiments.

[0028] Fig. 1 shows the configuration of a dolly 100 according to an embodiment of the present invention. Figs. 2 and 3 each show the configuration of a stacking dolly 200 in which dollies 100 of this embodiment are stacked. Fig. 2 shows the configuration of the stacking dolly 200 from the top side, and Fig. 3 shows the configuration of the stacking dolly 200 from the bottom side. Figs. 4 to 7 are respectively a top view (plan view), a bottom view (bottom view), a first side view (side view of the long side, front view / rear view), and a second side view (side view of the short side, right side view / left side view) showing the configuration of the dolly 100 of this embodiment.

[0029] As shown in Figs. 1 to 3, the trolley 100 according to the present invention has a stackable structure and is composed of a trolley body 10 and casters 30 attached to the four corners of the underside 14 of the trolley body 10. The trolley body 10 of this embodiment has a hollow molded structure and is relatively strong and lightweight, so that it is easy to stack and organize. The trolley body 10 of this embodiment is made of resin, for example, ultra-high molecular weight polyethylene. The trolley body 10 made of ultra-high molecular weight polyethylene has the characteristic of being resistant to impact and not cracking. The trolley body 10 is not limited to being made of ultra-high molecular weight polyethylene, and may be made of other materials (for example, polypropylene or engineering plastics). In the configuration of this embodiment, the hollow molded structure of the trolley body 10 is produced by blow molding.

[0030] In the configuration of this embodiment, as shown in Figs. 1, 2 and 4, the upper surface 11 of the dolly body 10 is provided with caster storage recesses 20 for storing the casters 30 attached to the lower surface 14 of the dolly body 10 arranged in the upper stage at positions corresponding to the four corners. In other words, in the example shown in Fig. 2, the upper surface 11 of the dolly body 10 of the dolly 100 (100C) is provided with the caster storage recess 20, and the caster 30 of another dolly 100 (100D) stacked on the dolly body 10 of the dolly 100 (100C) is stored in the caster storage recess 20. Although the dollies 100C and 100D have been described as examples, the same applies to the other dollies 100. In the configuration of this embodiment, the stacking dollies 200 shown in Figs. 2 and 3 each have the same structure.

[0031] In the configuration of this embodiment, as shown in Figs. 1, 2 and 4, the upper surface 11 of the carriage body 10 is provided with a fitting recess 25. As shown in Figs. 3 and 5, the lower surface 14 of the carriage body 10 is provided with a fitting protrusion 26 having a shape that can fit into the fitting recess 25. In other words, the lower surface 14 of the carriage body 10 of the carriage 100 (100D) arranged in the upper stage is provided with the fitting protrusion 26, which is inserted into the fitting protrusion 26 of the carriage body 10 of the carriage 100 (100C) below. Although the carriages 100C and 100D have been described as examples, the same is true for the other carriages 100. The fitting recess 25 may be referred to as a first hole portion or a first fitting member (a stacking stabilizing member, a stacking stabilizing means), and the fitting protrusion 26 may be referred to as a second protrusion portion or a second fitting member (a stacking stabilizing member, a stacking stabilizing means).

[0032] To explain further, in a structure in which the dolly body 10 and the dolly body 10 arranged in the upper stage are stacked, the fitting protrusion 26 of the dolly body 10 arranged in the upper stage is inserted into the fitting protrusion 26 of the dolly body 10. Then, as shown in FIG. 2, a gap S is generated between the lower end 30b of the caster 30 of the dolly body 10 arranged in the upper stage and the upper surface 20t of the caster storage recess 20 of the dolly body 10. In other words, in a structure in which the upper stage dolly 100D and the dolly 100C thereunder are stacked, the lower end 30b of the caster 30 of the upper stage dolly 100D is not in contact with the upper surface 20t of the caster storage recess 20 of the dolly 100C thereunder, and a gap S is generated between the lower end 30b of the caster 30 and the upper surface 20t of the caster storage recess 20 located immediately below it. Although the description has been given taking the carriages 100C and 100D as examples, the same applies to the other carriages 100. The gap S in this embodiment is, for example, 5 mm or less, and in the smallest case, the gap S is 1 mm.

[0033] The trolley 100 (and stacking trolley 200) of this embodiment has such a structure, and therefore can realize a trolley (stacking trolley) that is stable even when stacked. To explain further, according to the configuration of this embodiment, a caster storage recess 20 for storing the caster 30 of the trolley body part 10 arranged in the upper tier is provided on the upper surface 11 of the trolley body part 10 having the casters 30 attached to the four corners, and in a structure in which the trolley body parts 10 are stacked, the fitting protrusion 26 of the upper tier trolley body part 10 is inserted into the fitting recess 25 of the trolley body part, and a gap S is generated between the lower end 30b of the caster 30 of the upper tier trolley body part 10 and the upper surface 20t of the caster storage recess 20. As a result, even when the trolley body parts 10 of the trolleys 100 (100A to 100D) are stacked, the lower end 30b of the upper caster 30 does not come into contact with the trolley body parts 10 (trolleys 100) below, so that the trolleys can be stacked stably without rattling. In particular, according to the configuration of this embodiment, it is possible to stack five or more trolleys 100 (particularly, ten or more, twelve or more). According to the trolley 100 (and stacking trolley 200) of this embodiment, a trolley (stacking trolley) that is stable even when stacked can be realized. The gap S in this embodiment may be 0.1 mm, and in an extreme case, the gap S may be 0 mm. Even if the gap S is 0 mm, in a structure in which the upper dolly 100D and the dolly 100C below it are stacked, the load is applied to the upper dolly body 10 and the dolly body 10 below it, so even if the lower end 30b of the caster 30 is in contact with the upper surface 20t of the caster storage recess 20, there is no wobbling, and a dolly (stacking dolly) that is stable even when stacked can be realized. In addition, even if the gap S is 1 mm or less (for example, 1 mm or 0.5 mm, etc.), depending on the stacking state, the lower end 30b of the caster 30 may come into contact with the upper surface 20t of the caster storage recess 20 due to the load, but even in that case, the load is applied to the upper dolly body 10 and the dolly body 10 below it, so even if the lower end 30b of the caster 30 is in contact with the upper surface 20t of the caster storage recess 20, there is no wobbling, and a stable stacked structure can be maintained.

[0034] Furthermore, the configuration of the cart 100 (and stacking cart 200) of this embodiment will be described. In the configuration of this embodiment, the stacking cart 200 has a structure in which at least four carts 100 (100A to 100D) are stacked. Each of the at least four carts 100 (100A to 100D) has the same structure.

[0035] In the configuration of this embodiment, the upper surface 11 of the dolly body 10 is a loading platform surface on which luggage is placed. Since luggage is placed on the upper surface 11 of the dolly body 10, it is preferable that the upper surface 11 of the dolly body 10 is substantially flat (planar). In the configuration of this embodiment, the fitting recess 25 is provided on the upper surface 11 of the car body 10, and the fitting protrusion 26 is provided on the lower surface 14 of the dolly body 10, so that the upper surface 11 of the dolly body 10 can be made substantially flat (planar) by providing the fitting recess 25 on the upper surface 11 of the car body 10. In other words, even if the combination of the fitting recess 25 and the fitting protrusion 26 is reversed, the upper dolly body 10 and the lower dolly body 10 can be stacked and fixed, but in that case, the fitting protrusion 26 will be located on the upper surface 11 of the dolly body 10, so a protrusion (protrusion) will be generated on the loading platform surface (11) on which luggage is placed. It is sufficient if the loading platform surface (11) can tolerate the presence of protrusions (protrusions), but if this is not the case, it is preferable to provide an engaging recess 25 on the upper surface 11 of the trolley main body 10 and an engaging protrusion 26 on the lower surface 14 of the main body 10.

[0036] In the configuration of this embodiment, the fitting recess 25 and the fitting protrusion 26 have a shape that fits into each other. In the illustrated example, the fitting recess 25 and the fitting protrusion 26 have an L-shape. This is because, compared to something like a circle (for example, a combination of a cylinder and a circular hole), a shape that extends in two directions (for example, an X-axis-Y-axis) (L-shape or cross shape) is relatively difficult to come off even if vibration is applied to the dolly 100. In addition, such a shape (L-shape or cross shape) is characterized in that it is relatively easy to fit into compared to a complicated shape. However, the shape of the combination of the fitting recess 25 and the fitting protrusion 26 is not limited to an L-shape (approximately L-shape), but may be a cross shape (approximately cross shape), a quadrangle (square, rectangle), an ellipse (track-shaped oval), or the like. The fitting recess 25 and the fitting protrusion 26 may have any shape that allows them to fit together, and may have a complex shape (such as a wave shape or star shape) or may be circular, although this may make them difficult to fit together.

[0037] In the configuration of this embodiment, four combinations of the fitting recesses 25 and the fitting protrusions 26 are formed. Specifically, four fitting recesses 25 are provided inside the caster storage recesses 20 provided at the four corners of the upper surface 11 of the dolly body 10. Also, four fitting protrusions 26 are provided inside the casters 30 provided at the four corners of the dolly body 10 on the lower surface 14 of the dolly body 10. Although four or more (five or more) combinations of the fitting recesses 25 and the fitting protrusions 26 can be provided, four combinations are sufficient to stably fix the fitting. Although less than four (three or less) combinations of the fitting recesses 25 and the fitting protrusions 26 can be fixed, it is preferable to provide two (for example, diagonally opposite positions) in order to stabilize the stacking of the dolly body 10.

[0038] The dolly body 10 has a rectangular shape when viewed from above. The term "rectangle" as used herein includes a square shape, and is not limited to a rectangle in the strict geometric sense, but also includes a substantially rectangular shape (approximately rectangular shape) such as a shape with rounded corners. That is, since the upper surface 11 of the dolly body 10 is a loading platform surface on which luggage is placed, it does not need to be a rectangle in the strict geometric sense, and it may have any shape that functions appropriately as a loading platform surface on which luggage is placed. In addition, when viewed from above, this refers to the viewpoint shown in FIG. 4, and does not mean that it is seen by the human eye. In addition, as shown in FIG. 5, the dolly body 10 also has a rectangular shape when viewed from below. As shown in FIG. 4 and FIG. 5, the dolly body 10 of this embodiment has a rectangular shape with slightly rounded corners. In addition, as long as it functions as a loading platform surface on which luggage can be placed, the cart main body 10 does not necessarily have to be rectangular when viewed from above, and may be other shapes (for example, circular, elliptical, oval (truck-shaped), polygonal (triangular, hexagonal, etc.) and in that case, the four corners will be positioned corresponding to the locations where the cart main body 10 can be stably supported by the casters 30.

[0039] In the configuration of this embodiment, the dolly body 10 has handles (36, 37). As shown in Figs. 1 and 4, in the illustrated configuration example, the handles (36, 37) are provided on each of the four rectangular sides of the dolly body 10. In this manner, the handles (36, 37) are provided on all four sides of the dolly body 10, making it easy and convenient to grasp the dolly 100. The handle 36 is a part (center) of the long side of the dolly body 10, and the handle 37 is a part (center) of the short side of the dolly body 10. The handles (36, 37) are formed by through holes (28, 29) formed in the outer edge of the dolly body 10. Specifically, the handle 36 is formed by a through hole 28 formed in a part (center) of the outer edge of the long side of the dolly body 10. The handle 37 is formed by a through hole 29 formed in a part (center) of the outer edge of the short side of the cart body 10. The through holes (28, 29) in this embodiment have an oval shape (truck shape), but may have other shapes (for example, rectangular). In the configuration of this embodiment, the handles (36, 37) are formed by the through holes (28, 29) formed in the outer edge of the cart body 10, so there is no need to provide a handle on the outside of the cart body 10, and therefore it is easy to arrange the cart body 10 (cart 100) in a tiled manner (arrange multiple rectangles in a matrix with no gaps).

[0040] The dolly body 10 of this embodiment has a hollow structure made of resin and is formed by blow molding. Since the dolly body 10 is made of resin, it can be made more flexible in shape than a wooden dolly. Furthermore, since the dolly body 10 has a hollow structure, it is relatively light and convenient to use as a dolly. Although the dolly body 10 can be manufactured by other resin molding methods, when it is formed by blow molding, the upper surface 11 and the lower surface 14 can be easily manufactured in different shapes, which is convenient. In addition, blow molding is suitable for making a hollow structure made of resin. As described above, the dolly body 10 of this embodiment is made of ultra-high molecular weight polyethylene, which has the characteristic of being resistant to impact and not cracking, and is suitable for a dolly. Ultra-high molecular weight polyethylene (UHMW-PE (or UPE)) is a synthetic resin classified as a thermoplastic resin, one of the engineering plastics, and is polyethylene whose molecular weight, which is normally 20,000 to 300,000, has been increased to 1,000,000 to 7,000,000. In addition, a UV agent (ultraviolet absorbing agent) is blended into the resin of the trolley body 10 of this embodiment, so that it does not deteriorate even when used outdoors for a long period of time. Furthermore, biomass raw materials may be used for the resin of the trolley body 10 of this embodiment, contributing to CO2 reduction.

[0041] The bogie body 10 of this embodiment has a hollow structure made of resin, and in order to improve its strength, connection recesses (22, 23, 27) are formed to connect the upper surface 11 and the lower surface 14 of the bogie body 10. In the configuration of this embodiment, the connection recesses 22 and 23 formed on the upper surface 11 of the bogie body 10 are connected to the connection recess 27 formed on the lower surface 14 corresponding to the connection recess 22. In the illustrated example, the connection recess 22 is a hole (here, oval (track shape)) along the long side direction, and the connection recess 23 is a hole (here, oval (track shape)) along the short side direction. The bottom surfaces of the holes of the connection recesses 22 and 23 on the upper surface 11 are connected to the bottom surface of the hole of the connection recess 27 on the lower surface corresponding to the connection recess 22, and thus a structure in which a wall portion (column portion) is formed in the central region of the hollow bogie body 10 is formed, thereby increasing the strength of the bogie body 10.

[0042] As shown in Fig. 1 and Fig. 4, a caster storage recess 20 is formed at each of the four corners of the cart body 10. The caster storage recess 20 is composed of an upper surface 20t that is the bottom surface of the recess, and walls (20a, 20b) that surround the upper surface 20t. In this embodiment, the upper surface 20t of the caster storage recess 20 is rectangular, and the boundaries of the upper surface 20t are the wall 20a along the long side direction, the wall 20b along the short side direction, and the side surfaces 12 and 13 of the cart body 10. In the bogie body 10, the corner 20c where the wall 20a and the wall 20b intersect is likely to be weak, so in the configuration of this embodiment, the bending R of the wall 20a (the bending R at the boundary between the upper surface 11 and the wall 20a) and the bending R of the wall 20b (the bending R at the boundary between the upper surface 11 and the wall 20b) are made the same, and the bending R of the corner 20c (the bending R at the boundary between the upper surface 11 and the corner 20c) is made gentle (the radius of curvature is made large). This prevents the corner 20c from losing strength. Note that the specific radius of curvature of the bending R is determined appropriately depending on the performance and conditions required for the bogie 100, and is not limited to a specific number.

[0043] In addition, a cross-shaped recess 21 (21a, 21b) is formed on the underside 14 of the bogie body portion 10. By forming the recess 21 (21a, 21b) on the underside 14 of the bogie body portion 10, a rib shape can be formed, and the strength of the bogie body portion 10 can be increased. The recess 21a is formed along the long side of the rectangle, and the recess 21b is formed along the short side of the rectangle. A connection recess 27 is formed in the cross-shaped recess 21 provided on the underside 14 of the bogie body portion 10. In addition, a fitting protrusion 26 is formed in an area of ​​the underside 14 of the bogie body portion 10 where the cross-shaped recess 21 is not formed.

[0044] Furthermore, caster mounting recesses 35 for mounting casters 30 are formed at the four corners of the underside 14 of the dolly body 10. A caster mounting jig (caster metal fitting) 32 is attached to the caster mounting recess 35. The caster mounting jig 32 rotatably fixes the caster 30. The caster 30 of this embodiment is equipped with a bearing and rotates smoothly, which makes it easier to move the dolly 100 (move luggage).

[0045] As shown in Figs. 6 and 7, in the configuration of this embodiment, a wall portion 38 that defines the cross-shaped recess 21 is formed on the underside 14 of the dolly body 10. Also, a wall portion 36 that defines the caster mounting recess 35 is formed. The wall portion 38 and / or the wall portion 36 have an inclined surface (tapered shape). Also, on the upper surface 11 of the dolly body 10, the wall portion 20a and / or the wall portion 20b that defines the caster storage recess 20 have an inclined surface (tapered shape). By forming the wall portion 20 as an inclined surface (tapered shape) in this manner, there is an advantage that the mold can be smoothly removed during resin molding (particularly during blow molding).

[0046] Since the cart body 10 of this embodiment is formed by blow molding, as shown in FIG. 5, the lower surface 14 of the cart body 10 has an insertion mark 41 of a blow needle in blow molding. In addition, the lower surface 14 of the cart body 10 also has a mold removal mark 45 that is made when the cart body 10 is removed from the mold. When forming the cart body 10 by blow molding, only one blow needle needs to be inserted, but in this embodiment, in order to form the cart body 10 more uniformly, multiple blow needles are inserted in blow molding. Specifically, the blow needle is inserted into the locations of the blow needle insertion marks 41a and 41b (multiple locations, two locations) to blow air into the cart body 10. Furthermore, when it is desired to increase the accuracy, the blow needle is inserted into the locations of the blow needle insertion marks 41a to 41d (multiple locations, four locations) to blow air into the cart body 10. By carrying out such blow molding, the height H (the distance (H1 to H4) between the upper surface 11 and the lower surface 14) of the carriage body 10 shown in Figs. 5 and 6 can be made uniform.

[0047] The cart body 10 of this embodiment has a symmetrical structure (left-right and top-bottom symmetry, rotational symmetry) when viewed from above. Since the cart body 10 has a hollow structure, it is relatively difficult to make the height H (distance H1 to H4) of the cart body 10 uniform, but the error in the height H (distance H1 to H4) of the cart body 10 of this embodiment is set to 0.5 mm or less. This is because if the error in the height H (distance H1 to H4) (for example, the difference in height between the right side H1 and the left side H2 shown in FIG. 6) is 1 mm, if the carts 100 are stacked in 10 layers, the difference in total will be 10 mm, making it difficult to stabilize the stacked state. If the error is 0.5 mm or less (preferably 0.3 mm or less), the stacked state of the carts 100 can be made more stable. To make the height H (distances H1 to H4) of the carriage body 10 uniform, it is desirable to perform the manufacturing process so that the blowing needle is inserted at multiple locations (41a, etc.) for more uniform blowing and the resin in the mold cools at a uniform rate. In other words, it is desirable to control the temperature of the blow molding mold (to minimize the difference between the high-temperature and low-temperature resin in the mold and to make the resin hardening speed as uniform as possible).

[0048] 8 shows a stacking cart 250 in which the carts 100 of this embodiment are stacked in 10 or more layers (here, 12 layers). In the carts 100 of this embodiment, the height H (distances H1 to H4) of the cart main bodies 10 are uniform, so the carts are stable even when stacked in 10 or more layers. In this way, a large number of carts 100 can be organized, promoting efficient use of the work space in the factory.

[0049] Furthermore, the dolly 100 of this embodiment has a structure that allows it to stand on its own (at its side) on a horizontal ground. Specifically, as shown in FIG. 9, the dolly 100 can stand on its own at its side (12, 13). In the configuration of this embodiment, the dolly 100 can stand on its own at either side 12 or 13 on a horizontal ground, so that the handle 37 (36) can be held while the dolly 100 is standing on its own, which makes it convenient to move the dolly 100. Since it is more difficult for the dolly 100 of this embodiment to stand on its own at its side (short side) 13, a structure that allows it to stand on its own specifically at the side (long side) 12 of the dolly 100 may be used. Nevertheless, it is convenient because the dolly 100 can be moved by grabbing the handle 36.

[0050] Next, a manufacturing method of the cart body 10 constituting the cart 100 of this embodiment will be described with reference to Figures 10(a) to (c) and 11(a) to (c). Figures 10(a) to (c) and 11(a) to (c) are process diagrams for explaining the manufacturing method of the cart body 10.

[0051] The cart body 10 of this embodiment is manufactured by blow molding. In blow molding, plastic pellets (grains) are melted, mixed, and extruded by an extruder, and passed through a high-temperature metal cylinder (head) to form a molten resin (parison) into a cylindrical shape. The parison is sandwiched between metal molds, a needle is inserted, and high-pressure gas is blown in to press the parison against the inner surface of the mold with the pressure, and then the parison is cooled to form a hollow body.

[0052] First, as shown in Fig. 10(a), a parison 400 is extruded into a mold 300 that defines the structure of the cart body 10 (see arrow 510). The parison is a pipe made of thermoplastic resin, and the resin used in this embodiment is ultra-high molecular weight polyethylene. A blowing needle 310 is set in the mold 300. Note that in Fig. 10(a) and other figures, the mold 300 and the corresponding cart body 10 are depicted diagrammatically using easy-to-understand shapes, but the structure of the cart body 10 (and the corresponding mold 300) is as described above.

[0053] 10(b), the parison 400 is clamped by the mold 300 (see arrow 520) to perform mold clamping. As a result, the parison 400 enters the mold 300, and the part outside the mold 300 becomes the unnecessary part 410.

[0054] 10(c), the blow needle 310 is inserted. In this embodiment, as described above, in order to make the height H of the cart body 10 (the heights H1 to H2 at the four locations corresponding to the four corners) uniform, multiple blow needles 310 (two or four) are inserted. This allows the parison / mold to be inflated by applying uniform pressure to the fitting protrusions 26 (four locations) on the underside 14 of the cart body 10.

[0055] 11(a), gas is blown into the mold 300 from the blowing needle 310 (arrow 530), which causes the parison 400 to take the shape of the carriage body 10, and then the resin cools to produce a parison 401 having the shape of the carriage body 10. The resin is cooled by adjusting the height H (H1 to H4) of the carriage body 10 so that it is uniform.

[0056] Next, as shown in Fig. 11(b), the mold 300 is removed (arrow 540) to expose the cooled parison 402 (cart body 10). Thereafter, as shown in Fig. 11(c), the parison 403 (cart body 10) is removed (arrow 550) from the unnecessary portion 410 of the parison 400 using a removal tool (cutting tool) 350, and the burrs are removed to obtain the cart body 10.

[0057] Finally, the casters 30 are attached to the cart body 10, thereby completing the cart 100 of this embodiment.

[0058] The manufacturing method of the dolly 100 of this embodiment is performed by forming the dolly body 10 by blow molding using a mold 300, and then attaching the caster 30 to the underside 14 (caster attachment recess 35) of the dolly body 10. In the process of forming the dolly body 10, the mold 300 has a portion corresponding to the caster storage recess 20 of the dolly body 10, a portion corresponding to the fitting recess 25, and a portion corresponding to the fitting protrusion 26. In addition, in glow molding, the temperature of the mold (temperature during cooling) is adjusted so that the error in the distance H (H1 to H4) of the dolly body 10 to be formed is 0.5 mm or less.

[0059] Although the present invention has been described above using preferred embodiments, these descriptions are not limiting, and various modifications are possible. In addition, the features of the above-mentioned embodiments can be mutually applied as long as there is no technical contradiction. In addition, the dolly 100 of this embodiment is premised on stacking, but may be used alone. In addition, when the dolly 100 of this embodiment is stacked only in about four stages (or five stages or less), the error of the distance H (H1 to H4) of the dolly main body 10 may be more than 0.5 mm. In this embodiment, the stacking and fixing are stabilized by the combination of the fitting protrusion 26 and the fitting recess 25, but it is also possible to use other connecting members (magnets, hooks, etc.). However, considering the convenience of the dolly 100 and the small number of members (simplicity, few breakdowns, etc.), the combination of the fitting protrusion 26 and the fitting recess 25 is preferable. [Industrial Applicability]

[0060] According to the present invention, it is possible to provide a cart (stacking cart) that is stable even when stacked. [Explanation of symbols]

[0061] 10. Cart body 11 Top surface of the trolley body 12 Upper surface side of the trolley body (long side) 13 Side of the trolley body (short side) 14 Underside of the trolley body 20 Caster storage recess 20a, 20b Wall of caster storage recess 20c Corner of caster storage recess 20t Upper surface of the caster storage recess 21 (21a, 21b) Concave portion (cross concave portion on the back surface) 22, 23 Connection recess 25 Fitting recess 26 Fitting protrusion 27 Connection recess 28, 29 Through holes 30 Caster 30b Lower end of caster 32 Caster installation jig 35 Caster mounting recess 36, 37 Handle 38 Wall 41 Insertion mark 45 Die cut marks 100 Carts 200 Stacking Cart 250 Stacking Cart 300 Molds 310 Blowing needle 350 Removal tool 400 parison 1000 Cart (Stack Cart)

Claims

1. A stacking cart in which carts are stacked, The cart is A bogie main body; Casters attached to the four corners of the underside of the cart body; Equipped with The upper surface of the cart body is provided with a caster storage recess at a position corresponding to the four corners to store a caster attached to a lower surface of the cart body arranged in an upper stage, A fitting recess is provided on the upper surface of the carriage body, A fitting protrusion is provided on a lower surface of the carriage body portion arranged on the upper stage, In a structure in which the carriage body portion and the carriage body portion arranged on the upper stage are stacked, The fitting protrusion of the carriage body portion arranged in the upper stage is inserted into the fitting recess of the carriage body portion, and A stacking cart in which a gap is created between the lower end of the caster in the cart body portion arranged on the upper tier and the upper surface of the caster storage recess in the cart body portion.

2. The stacking cart has a structure in which at least four carts are stacked, The stacking cart of claim 1 , wherein each of the at least four cars has an identical construction.

3. The upper surface of the dolly body is a loading platform surface on which luggage is placed, The cart body has a rectangular shape when viewed from above, The stacking dolly of claim 1 , wherein a handle is present on each of the four sides of the rectangle.

4. The stacking cart according to claim 3 , wherein the handle is formed by a through hole formed in an outer edge of the cart body.

5. the fitting recess and the fitting protrusion have an L-shape that fits into each other, The stacking cart according to claim 1 , wherein four combinations of the fitting recess and the fitting protrusion are formed on one cart body portion.

6. The cart body is formed by blow molding, A connection recess is formed in the carriage body portion to connect the upper surface and the lower surface of the carriage body portion, The stacking cart according to claim 1 , wherein a plurality of insertion marks of blow needles used in blow molding are formed on the underside of the cart body.

7. The carriage body has a symmetrical structure when viewed from above, The carriage body has a hollow structure, 7. The stacking cart according to claim 1, wherein an error in the distance between the upper surface and the lower surface of the cart body is 0.5 mm or less.

8. A stackable dolly, The cart is A bogie main body; Casters attached to the four corners of the underside of the cart body; Equipped with A caster storage recess for storing casters of other carts stacked on the cart body is provided on the upper surface of the cart body at a position corresponding to the four corners, A fitting recess is provided on the upper surface of the carriage body, A fitting protrusion having a shape that can be fitted into the fitting recess is provided on the lower surface of the carriage body, In a structure in which the cart is stacked with another cart stacked thereon, The fitting protrusion of the other carriage is inserted into the fitting recess of the carriage, and A trolley in which a gap is generated between the lower end of the caster of the other trolley and an upper surface of the caster storage recess of the trolley.

9. The upper surface of the dolly body is a loading platform surface on which luggage is placed, The cart body has a rectangular shape when viewed from above, The carriage body has a hollow structure, A handle is present on each of the four sides of the rectangle; the fitting recess and the fitting protrusion have an L-shape, The bogie according to claim 8 , wherein four combinations of the fitting recess and the fitting protrusion are formed on one of the bogie main bodies.

10. The cart body is formed by blow molding, A connection recess is formed in the carriage body portion to connect the upper surface and the lower surface of the carriage body portion, A plurality of insertion marks of blow needles used in blow molding are formed on the underside of the cart body, The carriage body has a symmetrical structure when viewed from above, The cart according to claim 8 or 9, wherein an error in the distance between the upper surface and the lower surface of the cart body is 0.5 mm or less.

11. The dolly according to claim 8 or 9, wherein the dolly has a structure capable of standing on a horizontal ground at a side surface between an upper surface and a lower surface of the dolly body.

12. A stacking cart in which carts are stacked, The cart is A bogie main body; Casters attached to the four corners of the underside of the cart body; Equipped with The upper surface of the cart body is provided with a caster storage recess at a position corresponding to the four corners to store a caster attached to a lower surface of the cart body arranged in an upper stage, A fitting recess is provided on the upper surface of the carriage body, A fitting protrusion is provided on a lower surface of the carriage body portion arranged on the upper stage, In a structure in which the carriage body portion and the carriage body portion arranged on the upper stage are stacked, The fitting protrusion of the carriage body portion arranged in the upper stage is inserted into the fitting recess of the carriage body portion, and A stacking cart, wherein there is zero gap between the lower ends of the casters in the cart body portion arranged on the upper tier and the upper surface of the caster storage recess in the cart body portion.

13. A stackable dolly, The cart is A bogie main body; Casters attached to the four corners of the underside of the cart body; Equipped with A caster storage recess for storing casters of other carts stacked on the cart body is provided on the upper surface of the cart body at a position corresponding to the four corners, A fitting recess is provided on the upper surface of the carriage body, A fitting protrusion having a shape that can be fitted into the fitting recess is provided on the lower surface of the carriage body, In a structure in which the cart is stacked with another cart stacked thereon, The fitting protrusion of the other carriage is inserted into the fitting recess of the carriage, and A trolley, wherein there is zero gap between the lower ends of the casters of the other trolleys and an upper surface of the caster storage recesses of the trolley.

14. The dolly according to claim 13, wherein the dolly has a structure capable of standing on its own on a horizontal ground surface at a side surface between an upper surface and a lower surface of the dolly body.

15. A method for manufacturing a stackable dolly, comprising the steps of: forming a carriage body by blow molding using a mold; A step of attaching casters to a lower surface of the dolly body, In the step of forming the carriage body, the die includes a portion corresponding to a caster storage recess located on an upper surface of the cart body, a portion corresponding to a fitting recess located on the upper surface of the cart body, and a portion corresponding to a fitting protrusion located on a lower surface of the cart body, In the glow molding, the temperature of the mold is adjusted so that the error in the distance between the upper surface and the lower surface of the formed cart main body portion is 0.5 mm or less.

Images