Shelf plate

Abstract

To suppress narrowing of a storage space in a vertical direction while improving rigidity in a shelf board.SOLUTION: The shelf plate 12 includes a base plate 13 and a top plate 14. The substrate 13 is a flat plate along the width direction and the depth direction, and a convex portion 21 that protrudes in the thickness direction and extends in the width direction is formed. The top plate 14 is a flat plate along the width direction and the depth direction, and is overlaid on and welded to the upper surface of the substrate 13. In the convex portion 21, a convex height H along the thickness direction is twice or more the thickness t of the substrate 13, and a convex depth D along the depth direction is three times or more and eight times or less the convex height H.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a shelf board. [Background technology]

[0002] The showcase described in Patent Document 1 has metal reinforcing members with a U-shaped cross section welded to the rear surface of the flat shelf boards to increase rigidity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-65414 Summary of the Invention [Problem to be solved by the invention]

[0004] If a U-shaped metal reinforcing member is welded to the shelf board or if a protrusion is formed on the base of the shelf board, the shelf board will protrude in the thickness direction, thereby narrowing the storage space in the vertical direction. An object of the present invention is to improve the rigidity of a shelf board while preventing the storage space in the vertical direction from being narrowed. [Means for solving the problem]

[0005] A shelf board according to one aspect of the present invention comprises a base plate and a top plate. The base plate is a flat plate extending in the width and depth directions, and has a convex portion that is convex in the thickness direction and extends in the width direction. The top plate is a flat plate extending in the width and depth directions, and is overlapped and welded to the top surface of the base plate. The convex portion has a height in the thickness direction that is at least twice the thickness of the base plate, and a depth in the depth direction that is at least three times but not more than eight times the height of the convex portion. [Effects of the Invention]

[0006] According to the present invention, the convex portion is set according to the dimensions of the thickness of the board, the height of the convex portion, and the depth of the convex portion, thereby improving rigidity while preventing the storage space in the vertical direction from being narrowed. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. 10 is a diagram schematically illustrating a protrusion that provides high rigidity. [Figure 6] FIG. 10 is a diagram schematically illustrating a protrusion that does not have high rigidity. [Figure 7] FIG. 1 is a diagram illustrating a three-point bending test. [Figure 8] FIG. 10 is a diagram showing the comparison results. [Figure 9] FIG. 10 is a diagram showing the comparison results. [Figure 10] FIG. 10 is a diagram illustrating pitch. [Figure 11] FIG. 10 is a diagram showing a comparison result when the pitch is changed. [Figure 12] FIG. 10 is a diagram showing a comparison result when the convex width is changed. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings are schematic and may differ from the actual product. Furthermore, the following embodiments exemplify devices and methods for embodying the technical concept of the present invention, and are not intended to limit the configuration to those described below. In other words, the technical concept of the present invention can be modified in various ways within the technical scope described in the claims.

[0009] <<Embodiment>> "composition" In the following description, the three mutually orthogonal directions are referred to as a width direction, a depth direction, and a vertical direction. The width direction and the depth direction are horizontal directions. FIG. 1 is a diagram showing a showcase 11. As shown in FIG. Here, the showcase 11 is shown as seen from one side in the width direction. The showcase 11 is a display shelf for displaying products, and has a plurality of shelves 12 arranged vertically and fixed to a frame. The shelves 12 are formed as flat plates that extend in the width and depth directions, but may also be inclined so that the front end in the depth direction is downward.

[0010] FIG. 2 is a diagram showing the shelf board 12. As shown in FIG. The shelf board 12 is formed by joining a base plate 13 and a top plate 14. Here, the separated base plate 13 and top plate 14 are shown as viewed from one side in the width direction, one side in the depth direction, and from above in the up-down direction. The base plate 13 is a flat steel plate extending in the width and depth directions, and is formed into a rectangle with the width direction as the longitudinal direction when viewed from the top and bottom. The base plate 13 has a protrusion 21 formed thereon. The top plate 14 is a flat steel plate that extends in the width and depth directions, and has the same external shape as the base plate 13 when viewed from the top and bottom. It is placed on top of the base plate 13 and spot-welded to the base plate 13 at multiple welding points.

[0011] FIG. 3 is a diagram showing the substrate 13. As shown in FIG. (a) in the figure shows the state of the substrate 13 as viewed from above in the vertical direction, and (b) in the figure shows the state of the AA cross section of the substrate 13, which passes through the center in the width direction and is along the depth direction and vertical direction, as viewed from one side in the width direction. The protrusions 21 are beads that protrude downward in the vertical direction and extend in the width direction, and are formed in three locations lined up at intervals in the depth direction. The three protrusions 21 are formed at equal intervals along the depth direction. The protrusions 21 are provided to increase the bending rigidity when the substrate 13 is subjected to an out-of-plane load, and are formed by drawing. The protrusions 21 extend to both sides of the substrate 13 in the width direction. When viewed in the width direction, the protrusions 21 have a cross-sectional shape that resembles a bathtub curve.

[0012] In the substrate 13, the thickness t is the plate thickness dimension at the flat portion. In the protrusions 21, the protrusion width W is the dimension in the width direction, the protrusion depth D is the dimension in the depth direction, and the protrusion height H is the dimension in the thickness direction excluding the thickness t. In the protrusions 21, the protrusion circumferential length L is the dimension of the circumferential length passing through one side edge, the base edge, and the other side edge in that order in an open cross section along a plane perpendicular to the width direction. In the protrusions 21, the pitch P in the depth direction is the distance between the centers of the protrusion depths D. As shown in the following formula (1), the height H of the protrusion 21 is at least twice the thickness t. H≧2t ……(1)

[0013] The convex height H is 1 / 8 to 1 / 3 times the convex depth D. That is, as shown in the following formula (2), the convex depth D is 3 to 8 times the convex height H. 3H≦D≦8H ……(2) The pitch P is a dimension equal to or greater than the sum of the circumferential length L of the convex portion and the height H of the convex portion, as shown in the following formula (3). P≧L+H ……(3) The convex width W is a dimension that is equal to or greater than 70% and less than 100% of the distance Df between the support points along the width direction, as shown in the following formula (4). 0.7Df≦W<1.0Df ……(4)

[0014] FIG. 4 is a diagram showing the shelf board 12. As shown in FIG. FIG. 1(a) shows the shelf 12, in which the base plate 13 and the top plate 14 are joined, as viewed from above in the vertical direction. The base plate 13 and the top plate 14 are spot-welded at multiple welds 23, as shown by the hatching. The welds 23 are located only on both ends in the width direction, specifically, on both sides in the depth direction and in the center, for a total of six locations. The shelf 12, in which the base plate 13 and the top plate 14 are joined, has limited spot-welded welds 23, which prevents distortion of the shelf 12 and the occurrence of weld marks. Furthermore, the welds 23 can be made less noticeable by painting in a subsequent process, without impairing the design. (b) in the figure shows the BB cross section, which passes through the center of the width direction and is along the depth direction and the up-down direction, of the shelf board 12 in which the base plate 13 and the top plate 14 are joined, as viewed from one side in the width direction. By overlapping and joining the top plate 14 to the top surface of the base plate 13, the back side (concave portion) of the convex portion 21 is covered, and a flat upper surface is formed.

[0015] Next, the principle by which the substrate 13 has high rigidity will be described. FIG. 5 is a diagram schematically showing the protrusion 21 that provides high rigidity. In the figure, (a) shows the state of the protrusion 21 when not receiving a load, as viewed from one side in the width direction. The protrusion 21 has a tip surface 25 and a base end surface 26. The tip surface 25 is located at a vertical position corresponding to the lower surface of the protrusion 21 that protrudes most downward, and the base end surface 26 is located at a vertical position corresponding to the base of the protrusion 21, i.e., the lower surface of the flat portion of the substrate 13. We will focus on the deformation mode when a load is applied to the substrate 13 from above downward. (b) in the figure shows the state of the protrusion 21 deformed by the load, as viewed from one side in the width direction. The distal end surface 25 and the proximal end surface 26 of the protrusion 21 are in independent bending deformation modes, with the distal end surface 25 side experiencing tensile stress and the proximal end surface 26 side experiencing compressive stress. In this way, the mixture of tensile stress and compressive stress results in high-rigidity deformation. This high-rigidity deformation is achieved when the above-mentioned formulas (1) and (2) are satisfied.

[0016] FIG. 6 is a diagram showing a schematic view of a protrusion 21 that does not have high rigidity. (a) in the figure shows the state of the protrusion 21 deformed by the load, as viewed from one side in the width direction. Here, the case where the above-mentioned formula (1) is not satisfied is shown, that is, the protrusion height H is less than twice the thickness t. The protrusion 21 enters a bending deformation mode in which the distal end surface 25 and the proximal end surface 26 are integrated, and both the distal end surface 25 side and the proximal end surface 26 side are subjected to tensile stress. In other words, high rigidity cannot be achieved without a mixture of tensile stress and compressive stress. (b) in the figure shows the state of the protrusion 21 deformed by the load, as viewed from one side in the width direction. Here, the above-mentioned formula (2) is not satisfied, and for example, the protrusion depth D is more than 8 times the protrusion height H. The protrusion 21 is in a bending deformation mode only at the base end surface 26, and only the side of the base end surface 26 is subjected to compressive stress. Again, high rigidity cannot be achieved without a mixture of tensile stress and compressive stress.

[0017] Next, the three-point bending test will be described. FIG. 7 is a diagram illustrating the three-point bending test. (a) in the figure shows the state of a three-point bending test on substrate 13 as viewed from the thickness direction. (b) in the figure shows the state of a three-point bending test on substrate 13 as viewed from the depth direction. In a three-point bending test, substrate 13 is supported from below by two support points 31 extending in the depth direction on both sides in the width direction, and a bending load is applied to substrate 13 from above by an indenter 32 extending in the depth direction at the center in the width direction. This causes substrate 13 to bend along bending deformation line Lb extending in the depth direction. Here, the distance between support points 31 in the width direction is defined as Df.

[0018] Example A three-point bending test is performed, and the slope of the load [N] against the deformation [mm] of the substrate 13 is calculated as the rigidity [N / mm]. The thickness t is set to 1 mm for all samples, and the rigidity is compared when the convex height H is changed to 1 mm, 2 mm, and 3 mm, and when the convex depth D is changed to 4 mm, 8 mm, and 12 mm. FIG. 8 is a diagram showing the comparison results. (a) in the figure is a graph showing the relationship between the convex depth D / convex height H and rigidity. It was found that high rigidity can be achieved when the convex height H is at least twice the thickness t and the convex depth D / convex height H is at least three times the thickness t. (b) in the figure is a graph showing the analysis results based on stress distribution. It was found that the bending deformation mode, in which both tensile stress and compressive stress coexist, occurs when the convex height H is 2 mm or more and the convex width W is 8 mm or more.

[0019] Next, an embodiment in which the thickness t is changed will be described. The thickness t is kept constant at 0.5 mm for all components, and the rigidity is compared when the convex height H is changed to 1 mm, 2 mm, and 3 mm, and when the convex depth D is changed to 4 mm, 8 mm, and 12 mm. FIG. 9 is a diagram showing the comparison results. (a) in the figure is a graph showing the relationship between the convex depth D / convex height H and rigidity. (b) in the figure is a graph showing the analysis results based on stress distribution. When the convex height H was 1 mm and the convex depth D was 12 mm, the edge in the depth direction was short and the thickness t was as thin as 0.5 mm, and in addition, tensile stress and compressive stress were not mixed, so high rigidity was not achieved and the end in the depth direction of the convex portion 21 was deformed. Even when the convex height H / thickness t was 4 or 6 times, the convex depth D / convex height H was less than 3 times, so a high-rigidity bending deformation mode was not achieved. Therefore, it was found that high rigidity deformation is achieved when the above-mentioned formulas (1) and (2) are satisfied.

[0020] Here, the above-mentioned formula (3) will be explained. FIG. 10 is a diagram illustrating the pitch P. (a) in the figure shows the blank 15 before being drawn. A die 35, a punch 36, and a blank holder 37 are used for the drawing. The blank 15 is sandwiched between the die 35 and the blank holder 37 and is drawn by pressing down with the punch 36. (b) in the figure shows the substrate 13 after being drawn. If the dimension in the depth direction required between the convex portions 21 in the blank 15 is B, the pitch P is expressed by the following formula (5). Here, assuming drawing of a steel material with no fluctuation in thickness t, the blank material dimensions required to draw the material are shown as a guide. However, if the material has high elongation and the thickness t fluctuates, the formula (5) below is not the only applicable formula. P=L+B ……(5) The larger the convex height H, the greater the resistance to material flow, making drawing more difficult and requiring a depth dimension B. Therefore, the depth dimension B must be greater than or equal to the convex height H. This leads to the above-mentioned formula (3).

[0021] FIG. 11 is a diagram showing the comparison results when the pitch P is changed. (a) in the figure shows the state of the substrate 13 on which the protrusions 21 are formed at equal intervals, as viewed from above. (b) in the figure shows the state of the substrate 13 on which the protrusions 21 are formed at uneven intervals, as viewed from above. (c) in the figure shows the results of a comparison of rigidity. When the protrusions 21 are formed at uneven intervals, the rigidity is low where the pitch P is wide, making it more likely for local deformation to occur. In contrast, when the protrusions 21 are formed at equal intervals, the rigidity is uniform, making it less likely for local deformation to occur. When the protrusions 21 are formed at equal intervals, the rigidity is approximately 1.24 times higher than when they are formed at uneven intervals.

[0022] FIG. 12 is a diagram showing the results of a comparison in which the convex width W is changed. Here, we investigated the rigidity of the substrate 13 by varying the convex width W while maintaining a constant distance Df between the support points 31 in a three-point bending test. The convex width W / support distance Df represents the ratio of the convex width W when the support distance Df is 1.0. The larger the convex width W / support distance Df, the higher the rigidity of the substrate 13. However, the rate of increase in rigidity relative to the increase in the convex width W / support distance Df becomes smaller when the convex width W / support distance Df is 0.7 or greater. In other words, there is an inflection point in the rigidity when the convex width W / support distance Df is approximately 0.7, and the slope of the graph becomes gentler when the convex width W / support distance Df is 0.7 or greater. Therefore, by setting the convex width W / support distance Df to 0.7 or greater, stable high rigidity can be achieved, leading to the aforementioned formula (4).

[0023] <<Action and Effect>> Next, the main effects of the embodiment will be described. The shelf 12 includes a base plate 13 and a top plate 14. The base plate 13 is a flat plate extending in the width and depth directions, and is formed with a convex portion 21 that is convex in the thickness direction and extends in the width direction. The top plate 14 is a flat plate extending in the width and depth directions, and is overlapped and welded to the top surface of the base plate 13. The convex height H of the convex portion 21 in the thickness direction is at least twice the thickness t of the base plate 13, and the convex depth D of the convex portion 21 in the depth direction is at least three times but not more than eight times the convex height H. The convex portion 21 is set according to the thickness t, height H, and depth D of the base plate 13, thereby improving rigidity while minimizing the vertical storage space narrowing. The simple structure improves manufacturability and minimizes increases in cost and cycle time. The improved rigidity improves the load-bearing capacity of the shelf 12 by maintaining the thickness t of the base plate 13, and reduces the weight of the shelf 12 by reducing the thickness t of the base plate 13.

[0024] The protrusions 21 are formed at multiple locations spaced apart in the depth direction, with the depth direction pitch P being equal to or greater than the sum of the protrusion perimeter L of the open cross section along a plane perpendicular to the width direction and the protrusion height H. This allows for good drawing that takes into account the amount of material drawn in. The protrusions 21 are formed at equal intervals along the depth direction, which makes the rigidity uniform and makes it difficult for local deformation to occur. The shelf board 12 is supported by two support points 31 extending in the depth direction on both sides in the width direction. The convex width W of the convex portion 21 along the width direction is a dimension of 70% or more but less than 100% of the distance between the support points 31 along the width direction. This allows for stable, high rigidity to be achieved. The protrusions 21 are convex downward in the thickness direction. This allows the substrate 13 and the top plate 14 to be joined in an area that avoids the protrusions 21, improving the degree of freedom in the placement of the welding points. If a protrusion that is convex upward in the thickness direction is formed, the welding points will be provided on the top surfaces of the protrusions, reducing the degree of freedom in the placement of the welding points.

[0025] Although the present invention has been described above with reference to a limited number of embodiments, the scope of the invention is not limited thereto, and modifications of the embodiments based on the above disclosure will be obvious to those skilled in the art. [Explanation of symbols]

[0026] 11... showcase, 12... shelf board, 13... substrate, 14... top plate, 15... blank, 21... convex portion, 23... welding point, 25... tip surface, 26... base end surface, 31... support point, 32... indenter, 35... die, 36... punch, 37... blank holder

Claims

1. a substrate that is a flat plate along the width direction and the depth direction and has a convex portion that is convex in the thickness direction and extends in the width direction; a top plate that is a flat plate extending in the width direction and the depth direction and is overlapped on and welded to the top surface of the base plate; The convex portion has a height along the thickness direction that is at least twice the thickness of the base, and a depth along the depth direction that is at least three times and at most eight times the height of the convex portion.

2. The shelf board described in claim 1, characterized in that the convex portions are formed at multiple locations spaced apart in the depth direction, and the pitch in the depth direction is greater than or equal to the sum of the convex circumferential length of the open cross section along a plane perpendicular to the width direction and the convex height.

3. The shelf board according to claim 2, wherein the protrusions are formed at equal intervals along the depth direction.

4. It is supported by two support points extending in the depth direction on both sides in the width direction, The shelf board according to claim 1, wherein the convex portion has a convex width along the width direction that is 70% or more and less than 100% of the distance between the support points along the width direction.

5. The shelf board according to claim 1 , wherein the protrusions are protruded downward in the thickness direction.

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