KR20150095559A - Hollow structure - Google Patents

Abstract

A problem to be solved by the present invention is to prevent the sheet from being dented in a hollow structure in which both surfaces of a corrugated core having irregularities are covered with a synthetic resin sheet. The hollow structure of the present invention comprises a core material 2 made of synthetic resin having a concavo-convex structure in the thickness direction D1, a first sheet 8 made of synthetic resin covering one side of the core material 2, And a second sheet 10 made of synthetic resin covering the first sheet 10. A plurality of first convex portions 24 protruding on one side in the thickness direction D1 are arranged in a zigzag shape in plan view and a second convex portion 34 projecting on the other side in the thickness direction D1 is staggered In a plurality of shapes.

Description

[0001] HOLLOW STRUCTURE [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow structure, and more particularly, to a hollow structure including a core made of a synthetic resin and a sheet.

A hollow structure formed by using a synthetic resin is used as a member for assembling a product such as a container for transportation, a ladder, a bulletin board, and a partition for distribution.

Japanese Patent Application Laid-open No. Hei 10-156985 describes a conventional hollow structure made of synthetic resin. 10, the hollow structure is formed of a core material 102 made of a synthetic resin having a concave-convex shape and a pair of thermoplastic synthetic resin sheets 104 and 106. The core material 102 is formed by recessing a plurality of points on one surface of a thermoplastic synthetic resin sheet in a columnar shape and having a plurality of columnar recessed portions 110 on one surface side and a plurality of columnar recessed portions 112 are formed. A hollow structure is formed by heat-welding the synthetic resin sheets 104 and 106 to one surface side and the other surface side of the core material 102, respectively.

In the above-described conventional hollow structure, when the synthetic resin sheet 104 is heat-welded to one surface of the core member 102, the space in the recess 110 is clogged with the synthetic resin sheet 104 to become a sealed space. Therefore, when the temperature of the synthetic resin sheet 104 is lowered after the heat welding, the air volume in the closed space in the recessed portion 110 is reduced, and the synthetic resin sheet 104 is dented in various places.

In the hollow structure, if the surface of the synthetic resin sheet 104 is dented in various places, there is a problem that designability is lowered and that it is difficult to perform printing on the surface of the synthetic resin sheet 104.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to prevent a recessed sheet from being adhered to a core material in a hollow structure having a structure in which both surfaces of a core material made of synthetic resin having unevenness are covered with a sheet made of synthetic resin .

The hollow structure of the present invention comprises a core made of a synthetic resin having irregularities in the thickness direction, a first sheet made of synthetic resin covering the first side of the core in the thickness direction, and a second side of the core in the thickness direction And a second sheet made of a synthetic resin.

Wherein the core material includes a plurality of frustum-shaped or bar-shaped first convex portions projecting to the first side in the thickness direction in a zigzag manner in plan view, and a frustum shape or a bar-like shape projecting the second side in the thickness direction A plurality of second convex portions are arranged in a zigzag shape in plan view.

In another aspect of the present invention, the core member has a first surface facing the first side in the thickness direction, and a second surface facing the second side in the thickness direction. A plurality of first convex portions are arranged in a zigzag shape on the first surface, and a plurality of first concave portions are arranged in a zigzag shape. A plurality of second convex portions are arranged in a zigzag shape on the second surface, and a plurality of second concave portions are arranged in a zigzag shape. The first convex portion and the second concave portion are located one on the inside and one outside. The second convex portion and the first concave portion are located one on the inside and one outside.

In another aspect of the present invention, both of the first convex portion and the second convex portion are in the shape of a triangular frustum.

In another aspect of the present invention, it is preferable that the inclination of the side surfaces of the first and second convex portions is in the range of 6.0 to 45.0 占 and the bonding area ratio is in the range of 1 to 46%.

In another aspect of the present invention, it is more preferable that the inclination of the side surfaces of the first and second convex portions is in the range of 15.0 to 30.0 °, and the bonded area ratio is in the range of 14 to 40%.

It is more preferable that the inclination of the side surfaces of the first and second convex portions is in the range of 20 to 25 degrees and the bonding area ratio is in the range of 20 to 26 percent.

In another aspect of the present invention, it is preferable that the thickness of the core material is within a range of 3 to 30 mm.

In another aspect of the present invention, it is preferable that the cell size of the first convex portion and the second convex portion be all within a range of 5.0 mm to 15.0 mm. It is more preferable that the cell size of the first convex portion and the second convex portion is in a range of 8.0 to 10.0 mm.

In another aspect of the present invention, it is preferable that the core material is polypropylene.

In another aspect of the present invention, it is preferable that the compressive strength is in the range of 0.35 to 0.45 MPa, the bending strength is in the range of 17.2 to 23.7 Nm / m, or the bending rigidity is in the range of 4.8 to 6.6 Nm ² / m Do.

In another aspect of the present invention, it is preferable that the material of the core material, the material of the first sheet, and the material of the second sheet are the same.

In another aspect of the present invention, the first convex portion and the second convex portion of the core material are formed by thermoforming a sheet made of a synthetic resin using a mold, and are preferably formed continuously.

The method for producing a hollow structure according to the present invention is a method for producing a hollow structure by vacuum molding a core sheet made of a synthetic resin using a mold in which a plurality of recesses for vacuum suction are arranged in a zigzag shape to form a core material made of synthetic resin having unevenness in the thickness direction A step of adhering a first sheet made of a synthetic resin to the first side in the thickness direction of the core material and a step of adhering a second sheet made of synthetic resin to the second side in the thickness direction of the core material . The concave portion has a polygonal bottom surface, and a suction hole for vacuum suction is provided at a central portion of the bottom surface or at a position near a vertex.

1 is a perspective view of a hollow structure of a first embodiment of the present invention.
2 is a perspective view of a core material having a hollow structure of homology.
3 is a front view of the core material of the same size.
4 is a rear view of the core material of homology.
5 is a side view of the core material of homology.
6 is a schematic perspective view of a mold for molding a core material of the same size.
Fig. 7 is a front view of a recessed portion showing a basic size shape of a core material of the same size. Fig.
8 is a sectional view taken along line AA in Fig.
9 is a front view of a core material having a modified example of the hollow structure of the first embodiment of the present invention.
10 is a broken perspective view showing a main portion of a conventional hollow structure.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described based on embodiments shown in the accompanying drawings.

The hollow structure of the first embodiment of the present invention will be described with reference to Figs. 1 to 8. Fig.

1 is a perspective view of a hollow structure of the present embodiment. The hollow structure of this embodiment is a hollow structure in the form of a panel. In the hollow structure of the present embodiment, the first sheet 8 made of synthetic resin is attached to the first surface 4 of the core material 2 made of synthetic resin as shown in Figs. 2 to 5, The second sheet 10 made of a synthetic resin is adhered to the two surfaces 6.

The material of the core material 2, the first sheet 8 and the second sheet 10 may be polypropylene, polyethylene, polycarbonate, polylactic acid, or the like. The core material 2, the first sheet 8 and the second sheet 10 may be made of different materials, and they are preferably made of the same material so as not to be easily peeled off. The core material 2, the first sheet 8 and the second sheet 10 may each be a single layer or a plurality of layers of equivalent materials may be laminated. When an equivalent material is laminated, for example, block polypropylene and homopolypropylene are laminated.

 The core material 2 has a first side 4 on the first side in the thickness direction D1 of the core material 2 and a second side 6 on the second side in the thickness direction D1. The first surface 4 and the second surface 6 face opposite directions.

Fig. 2 is a perspective view of the core material 2, and Fig. 3 is a front view of the core material 2 as seen from the first surface 4 side. 4 is a rear view of the core material 2 as seen from the second surface 6. Fig. 5 is a side view of the core material 2. Fig. In the present specification, the state viewed from the thickness direction D1 of the core material 2 is referred to as "planar view" (plan view).

The core material 2 is a sheet material made of a synthetic resin having thermoplasticity (hereinafter referred to as a "core sheet ") and is obtained by processing corrugated iron on the core sheet according to the mold 16 shown in Fig. 6 . Specifically, a mold roll having a mold 16 on its surface is used, and one surface side of the core sheet softened by heating is sequentially sucked into the mold 16 while rotating the vacuum forming roll, The corrugated sheet is formed on the core sheet.

The mold 16 has a concavo-convex shape in which a plurality of concave portions 18 are arranged staggeredly (staggered). Each of the recessed portions 18 has a dimple shape having a triangular frustum shape. The bottom surface of each concave portion 18 has a regular triangular shape having the same dimensional shape. A suction hole 20 for vacuum suction is formed at the center of the bottom of each concave portion 18. Each recess 18 of the mold 16 functions as a suction cavity for vacuum suction. The suction hole 20 for vacuum suction may be formed at a position near each apex of the triangular bottom surface of each recess 18.

As used herein, the "zigzag shape" means a state in which they are arranged differently according to a predetermined reference direction. In the mold 16, when a perpendicular line is drawn at one vertex of a bottom surface of a triangle of the recess 18 and a direction parallel to the vertical line is set as a reference direction, (I.e., in a zigzag shape).

In the mold 16, a large number of convex portions 22 protruding in the shape of a triangular frustum are formed between adjoining triangular frustum-shaped concave portions 18. The plurality of convex portions 22 are arranged in a zigzag shape. The top surface of each convex portion 22 has a right triangular shape having the same dimensional shape.

The core material 2 having the concavo-convex structure formed by the vacuum molding using the mold 16 having the above-described configuration has a concavo-convex shape on the first face 4 and the second face 6 as shown in Figs. 2, 5, Is a member of synthetic resin.

The first surface 4 of the core material 2 has a first convex portion 24 in the form of a triangular frustum which is arranged in a zigzag form and a first prism portion 26 in the form of a triangular frustum, 16). Each of the first convex portions 24 is formed along each recessed portion 18 of the mold 16. Each of the first convex portions 24 has an equilateral triangular top surface. Each first recessed portion 26 is formed along each convex portion 22 of the mold 16. Each of the first recessed portions 26 has a bottom surface of a regular triangle shape.

In the first surface 4, three first convex portions 24 are disposed at positions spaced equidistantly in the circumferential direction (circumferential direction) surrounding the predetermined reference point 28. The reference point 28 is located at an intermediate portion of the core material 2 in the thickness direction D1. The first surface 4 has a plurality of such reference points 28 in a regular arrangement. The first surface 4 has a plurality of first convex portions 24 surrounding the reference points 28 in a continuous arrangement.

The first convex portion 24 has a ridge line 30. The ridgeline 30 has a small width. The ridgelines 30 of the three first convex portions 24 intersect at the reference point 28.

In the first surface 4, three first recessed portions 26 are arranged at positions spaced equidistantly in the circumferential direction around the predetermined reference point 28. [ The first recessed portion 26 has a bone line 32. The bone line 32 has a narrow width. The bone lines 32 of each of the three first recesses 26 intersect at the reference point 28.

The circumferential spacing between the first convex portions 24 surrounding the reference point 28 and the circumferential spacing between the first recesses 26 surrounding the reference point 28 may not be the same.

Further, the position of the reference point 28 may not be a strict intermediate point of the thickness direction D1. That is, the reference point 28 may be located at a position slightly deviated from the strict midpoint in the thickness direction D1.

The second surface 6 is in relation to the first surface 4 and the inside and outside (front and back). As shown in Fig. 4, the second surface 6 has a triangular frustum-shaped second convex portion 34 arranged in a zigzag shape and a plurality of second prism portions 36 arranged in a zigzag shape, 16). Each of the second convex portions 34 is on the inner side (back side) of the first recessed portion 26 of the first side 4. Each of the second convex portions 34 has an equilateral triangular prism face. The second recessed portion 36 is the inner surface side of the first convex portion 24 of the first surface 4. Each of the second recessed portions 36 has a bottom surface of a regular triangle shape.

In the second surface 6, three second convex portions 34 are disposed at positions spaced equidistantly in the circumferential direction around the predetermined reference point 38. [ The reference point 38 is located in the middle portion of the core material 2 in the thickness direction D1. The second surface 6 has a plurality of such reference points 38 in a regular arrangement. The second surface 6 has a plurality of second convex portions 34 surrounding the reference points 38 in a continuous arrangement. The reference point 38 of the second surface 6 and the reference point 28 of the first surface 4 are located inside and outside (front and back).

The second convex portion 34 has a ridge line 40. The ridgeline 40 has a small width. The ridgeline 40 of the three second convex portions 34 intersects at the reference point 38.

In the second surface 6, three second recessed portions 36 are disposed at positions spaced equidistantly in the circumferential direction around the predetermined reference point 38. [ The second recess (36) has a bone line (42). The bone line 42 has a narrow width. The bone lines 42 of the three second recesses 36 intersect at the reference point 38.

The circumferential spacing between the second convex portions 34 surrounding the reference point 38 and the circumferential spacing between the second recesses 36 surrounding the reference point 38 may not be the same. Further, the position of the reference point 38 may be a position deviated a large number from a strict midpoint of the thickness direction D1.

The vicinity of the reference point 38 is a place where wrinkling is likely to occur during vacuum molding. This crease is called a bridge. When a bridge is formed in the vicinity of the reference point 38, the other part is thinned to reduce the compressive strength. The core material 2 may be easily crushed when the first sheet 8 or the second sheet 10 is adhered to the core material 2 due to the decrease in the compressive strength.

The bridge tends to be more likely to occur as the inclination angle of the second recessed portion 36 surrounding the reference point 38 becomes closer to the vertical. Also, the bridge tends to occur as the radius of curvature of the ridge line 40 of the second convex portion 34 surrounding the reference point 38 is smaller.

For this reason, the preferable conditions for preventing the occurrence of bridges is that the inclination of the sidewall of the second recessed portion 36 in the vertical plane is 20 degrees or more and the ridge line 40 of the second convex portion 34 has a radius of curvature As shown in FIG. More preferable conditions are that the inclination of the sidewall of the second recessed portion 36 in the vertical plane is 20 degrees or more and the radius of curvature of the ridgeline 40 of the second convex portion 34 is 1 mm or more.

The second convex portion 34 of the second surface 6 is formed along the convex portion 22 of the mold 16 and the second concave portion 36 of the second surface 6 is formed along the convex portion 22 of the mold 16, Are formed along the respective recessed portions (18). Therefore, preferable conditions for preventing the bridge formation during vacuum forming are that the inclination of the sidewall of each concave portion 18 in the vertical plane is 20 degrees or more and the ridge line of each convex portion 22 is 0.5 mm or more Is set to be an iron curved surface having a radius of curvature of 1 mm or more.

It is preferable that the radius of curvature of the ridgeline of each convex portion 22 of the mold 16 is set to be smaller than the radius of curvature of each of the valleys 18 of the mold 16 by only a predetermined dimension. The predetermined dimension is a dimension corresponding to the thickness of the core sheet used for the core material 2. With this setting, the radius of curvature of the ridgeline 30 of the first convex portion 24 of the core material 2 after molding can be made equal to the radius of curvature of the ridgeline 40 of the second convex portion 34. [

The first sheet 8 adhered to the first surface 4 of the structure is heat welded to each of the apical surfaces of a plurality of first convex portions 24 arranged in a staggered manner on the first surface 4. [

The second sheet 10 adhered to the second surface 6 of the structure is heat welded to each of the apical surfaces of the plurality of second convex portions 34 arranged in a staggered manner on the second surface 6. [

At this time, the space formed between the first surface 4 and the first sheet 8 of the core material 2 is entirely communicated through a space between the adjacent first convex portions 24, And also communicates with each other. On the side of the first surface (4), there is no closed space blocked by the first sheet (8), so that the first sheet (8) is prevented from being dented after heat welding.

Similarly, the space formed between the second surface 6 of the core material 2 and the second sheet 10 is entirely communicated through spaces between adjacent second convex portions 34, . On the side of the second surface 6, since there is no closed space blocked by the second sheet 10, the occurrence of many recesses in the second sheet 10 after the heat welding is prevented.

In addition, the hollow structure formed by sandwiching the core material 2 from the both sides with the sheets 8 and 10 becomes an excellent isotropic panel.

Figs. 7 and 8 show the basic dimensional relationship of the hollow structure of this embodiment. Fig. 7 shows a basic arrangement of the first convex portions 24 on the first surface 4 side. Fig. 8 shows a cross section taken along the line A-A in Fig.

The basic shape of the first convex portion 24 (that is, the shape of the triangular frustum set virtually set to represent the first convex portion 24) is a triangular-shaped bottom surface 50 and a bottom surface 50, And has three side surfaces 54 connecting one side of each side of each of the sides of the lower floor 50 and the upper floor 52 in a one-to-one relationship.

The bottom surface 50 is a virtual image surface that is imaginarily positioned so as to be positioned in the middle of the thickness direction D1 of the core material 2. [ The respective vertexes of the bottom surface 50 coincide with the reference point 28. [ The lower bottom surfaces 50 of the adjacent three first convex portions 24 are vertically overlapped with each other at the reference point 28. [

Each side surface 54 is formed so as to be inclined at an angle of θ [mm] with respect to a vertical plane (a plane parallel to the thickness direction D1 of the core material 2) perpendicular to the lower floor surface 50 or the upper floor surface 52, °]. The apexes of the lower floor 50 and the apexes of the upper floor 52 are connected one to one with the ridge 30 therebetween.

The arrangement of the first convex portions 24 on the first surface 4 is set on the basis of the hexagonal cell 60. The cell 60 is a virtual compartment arranged in a honeycomb form on the first surface 4 side. In the six vertices of each cell 60, the three vertices skipped one by one coincide with the reference point 28.

The arrangement and dimension of the second convex portion 34 on the second surface 6 are the same as the arrangement and dimension of the first convex portion 24 on the first surface 4. [

7 and 8 show the relationship between the cell size CS [mm], the total thickness Tb [mm] of the hollow structure, the total thickness Tc [mm] And the thickness Tss [mm] of the first sheet 8 and the second sheet 10, respectively. The cell size CS is the dimension between two parallel sides of the cell 60.

The thickness Tc of the hollow structure Tb = 5.6 mm, the thickness Tc of the core material 2 = 4.8 mm and the thickness Tc of the core sheet 2 forming the core material 2 in the present embodiment The thickness Tcs = 0.3 [mm], and the thickness Tss of the first sheet 8 and the second sheet 10 = 0.4 [mm]. The inclination of the first convex portion 24 is set at an angle? = 25.0 [deg.].

Since the cell 60 is regular hexagonal, the area S0 of each cell 60 provided with the cell size CS = 9.0 [mm] is approximately 70.1 [mm ² ]. The area S2 of the lower floor surface 50 of the first convex portion 24 is equal to 35.1 mm ² and the area of the upper floor surface 52 is 14.1 mm ² .

A first ratio of the area S1 [mm ^2] of the bottom surface 52 to the area S2 [mm ^2] for having the convex portions 24 and the bottom surface 50 is S1 / S2 ≒ 40 [%] . The upper bottom surface 52 of the first convex portion 24 is an adhesive surface to which the first sheet 8 is adhered by heat fusion.

Therefore, the adhesion area ratio in each cell 60 is S1 / S0? 20 [%]. The "adhesive area ratio" used in the present specification means the ratio occupied by the adhesive surface in the entire area in plan view.

Each of the cells 60 is equally divided into a plurality of hexagons on one side of the core material 2 so that the adhesive area ratio S1 / S0? 20 [%] Is equal to the adhesive area ratio of the entire one surface. These dimensional relationships are the same on the side of the second surface 6 on which the second convex portions 34 are arranged in a zigzag shape.

That is, in the hollow structure of the present embodiment, frustum-shaped first convex portions 24 arranged in a staggered shape on the outer (table) side of the core material 2 and staggered first convex portions 24 arranged on the back side of the core material 2 And has a basic shape in which the area ratio of the upper floor to the lower floor is about 40 [%] and the inclination [theta] is 25.0 [deg.], Together with the frustum- Both the outer side and the inner side of the core material 2 have an adhesive area ratio of about 20%. Further, the thickness Tc of the core material 2 is 4.8 [mm], and the thickness Tcs of the core sheet constituting the core material 2 is 0.3 [mm].

The adhesive strength of the core material 2 to the first sheet 8 or the second sheet 10 is sufficiently high because the adhesive area ratio thereof is about 20%. Since the hollow structure of the present embodiment is made of polypropylene, the compressive strength is in the range of 0.35 to 0.45 [Mpa] under the above conditions, the bending strength is in the range of 17.2 to 23.7 [Nm / m] An experimental result that it is within the range of 4.8 to 6.6 [Nm2 / m] is obtained.

Therefore, the hollow structure of the present embodiment can be used for various purposes related to the load. Further, the hollow structure of the example has a weight per unit area of 990 g / mm ² , and is about 20% of the weight of the plate made of the same material.

The actual hollow structure is somewhat distorted in the thickness direction as a whole at the pressure when the first sheet 8 and the second sheet 10 are adhered. Therefore, in actuality, the thickness Tb of the hollow structure is in the range of 4.3 to 4.9 [mm], and the thickness Tc of the core material 2 is in the range of 3.5 to 4.1 [mm].

In Table 1 below, a plurality of parameters defining the dimensional shape of the hollow structure of the present invention are changed within a certain range. R in Table 1 is the bonded area ratio.

The cell size CS is set to be constant at 9.0 [mm] and the inclination [theta] is changed within the range of 5.6 to 49.7 [deg.] At No.1 to No.11 in Table 1 below, and the adhesive area ratio R (= S1 / S0). In No. 12 to No.27 of Table 1, the inclination θ was constantly set at 25.0 [°], the cell size CS was varied within the range of 3.3 to 500.0 [mm], and the adhesive area ratio R = S1 / S0). Though not shown in Table 1, when the angle? = 0, the first convex portion 24 and the second convex portion 34 become bar-shaped.

In any of Nos. 1 to 27 of Table 1 below, the thickness Tb of the hollow structure is 5.6 mm, the thickness Tc of the core material 2 is 4.8 mm, the thickness Tcs of the core sheet is 0.3 [ mm], and the thickness Tss of the first sheet 8 and the second sheet 10 is 0.4 [mm]. The thicknesses Tb [mm] and Tc [mm] of the hollow structure and the core material 2 are actually smaller than those due to the deformation at the time of sheet adhesion.

D [mm] shown in Table 1 is a distance between a vertex on the triangle of the upper floor 52 and another adjacent cell 60. In the following Table 1, the case of No. 6 and the case of No. 16 are the same.

No. CS
[mm] θ
[°] S1
[mm ² ] S0
[mm ² ] R
[%] D
[mm] One 9 5.6 32.83 70.15 47 0.00 2 9 6.0 32.39 70.15 46 0.03 3 9 10.0 28.14 70.15 40 0.32 4 9 15.0 23.14 70.15 33 0.69 5 9 20.0 18.45 70.15 26 1.09 6 9 25.0 14.05 70.15 20 1.50 7 9 30.0 9.98 70.15 14 1.95 8 9 35.0 6.30 70.15 9 2.44 9 9 40.0 3.16 70.15 5 3.00 10 9 45.0 0.87 70.15 One 3.64 11 9 49.7 0.00 70.15 0 4.35 12 3.3 25.0 0.00 9.43 0 1.50 13 4.0 25.0 0.21 13.86 2 1.50 14 5.0 25.0 1.25 21.65 6 1.50 15 8.0 25.0 9.55 55.43 17 1.50 16 9.0 25.0 14.05 70.15 20 1.50 17 10.0 25.0 19.42 86.60 22 1.50 18 15.0 25.0 59.24 194.86 30 1.50 19 20.0 25.0 120.71 346.41 35 1.50 20 30.0 25.0 308.61 779.42 40 1.50 21 40.0 25.0 583.11 1385.64 42 1.50 22 50.0 25.0 944.21 2165.06 44 1.50 23 60.0 25.0 1391.92 3117.69 45 1.50 24 70.0 25.0 1926.23 4243.52 45 1.50 25 80.0 25.0 2547.14 5542.56 46 1.50 26 90.0 25.0 3254.65 7014.81 46 1.50 27 100 25.0 4048.76 8660.25 47 1.50

The present inventors conducted various experiments while varying a plurality of parameters defining the dimensional shape of the hollow structure as shown in Table 1, and obtained the following results.

That is, in the hollow structure of the present invention, the first convex portion 24 and the second convex portion 34 are set to be within the range of the angle? = 6.0 to 45.0 占 together, and the first face 4 and the second face 6) was set within the range of R = S1 / S0 = 1 to 46 [%], it was found that good results were obtained as the compressive strength, bending strength, peel strength and formability of the hollow structure. At this time, the thickness Tc of the core material 2 is set within the range of 3 to 30 [mm], the thickness Tcs of the core sheet constituting the core material 2 is set within the range of 0.2 to 0.8 [mm] The thickness Tss of the sheet 8 and the second sheet 10 is set within a range of 0.2 to 1.2 mm.

The inventors of the present invention set the first and second convex portions 24 and 34 together in the range of angle θ = 15.0 to 30.0 ° and the first and second surfaces 4 and 6, The bending strength, the peel strength and the moldability of the hollow structure were obtained when the adhesive area ratio R = S1 / S0 = 14 to 40 [%]. The inventors of the present invention set the first convex portion 24 and the second convex portion 34 together within the range of the angle? = 20.0 to 25.0 占 and the distance between the first face 4 and the second face 6 When the adhesive area ratio was set within the range of R = S1 / S0 = 20 to 26 [%], it was found that better results were obtained as the compressive strength, bending strength, peel strength and formability of the hollow structure. In this case, too, the thickness Tc of the core material 2 is set within the range of 3 to 30 [mm], the thickness Tcs of the core sheet constituting the core material 2 is set within the range of 0.2 to 0.8 [mm] The thickness Tss of the first sheet 8 and the second sheet 10 is set within the range of 0.2 to 1.2 mm.

The inventors of the present invention found that when the cell size CS was set within the range of 5.0 to 15.0 mm, good results were obtained as the compressive strength, the bending strength, the peel strength and the moldability of the hollow structure, When it was set within the range of 80 to 10.0 [mm], better results were obtained.

Next, a modification of the hollow structure of the first embodiment of the present invention will be described with reference to Fig. 1 to 8 are denoted by the same reference numerals, and detailed description thereof is omitted.

In the modified hollow structure, as shown in Fig. 9, the top surfaces of the first convex portions 24 adjacent to each other on the first surface 4 are displaced in one direction. That is, on the first surface 4 shown in FIG. 3 and the like, the top surfaces of the adjacent first convex portions 24 are arranged so that one side of a regular triangle is positioned in a straight line. On the contrary, in the modification shown in FIG. 9, the apical surfaces of the adjacent first convex portions 24 are disposed so that one side of a regular triangle is not located on a straight line.

The bottom surfaces of the adjacent first recessed portions 26 on the first surface 4 are also arranged so as to be offset in one direction. That is, in the modified example, the bottom surfaces of the adjacent first recessed portions 26 are arranged so that one side of a regular triangle is not positioned in a straight line.

The second surface 6 of the core material 2 is in and out of relation to the first surface 4. [ Therefore, the arrangement of the second convex portion 34 and the second concave portion 36 formed on the second surface 6 is the same as that of the first convex portion 24 and the first concave portion 26 on the first surface 4 side Layout.

As described above with reference to the accompanying drawings, the hollow structure of the first embodiment of the present invention has the core material 2 made of synthetic resin having the concavo-convex in the thickness direction D1 and the core material 2 covering the first side in the thickness direction D1 of the core material 2 A first sheet 8 made of synthetic resin and a second sheet 10 made of synthetic resin covering the second side of the core material 2 in the thickness direction D1. The core material (2) has a plurality of frustum-shaped or bar-shaped first convex portions (24) protruding from the first side in the thickness direction D1 in a zigzag manner in plan view, Like frustum-shaped or rod-shaped second convex portions 34 are arranged in a zigzag manner in plan view.

According to the hollow structure having the above-described structure, when the first sheet 8 or the second sheet 10 of the core material 2 is adhered, no sealed space is formed, (10) is prevented from being depressed.

For this reason, the hollow structure having the above-described structure is highly designable and hardly attracts dust on its surface. In addition, it is possible to perform simple and neat printing on the surfaces of the first sheet 8 and the second sheet 10. When another material such as aluminum is attached to the surfaces of the first sheet 8 and the second sheet 10, it is also easy to provide the adhesive strength to such an extent that it can not be easily peeled off. In addition, the hollow structure of the above structure has an advantage that it is difficult to cause a difference in design outside and inside, but there is an advantage that a physical property difference between the outside and inside is hard to occur. This makes it possible to produce a product regardless of whether the hollow structure is inside or outside.

In the hollow structure of the first embodiment, the core material 2 has a first side 4 facing the first side in the thickness direction D1 and a second side 6 facing the second side in the thickness direction D1. A plurality of first convex portions 24 are arranged in a zigzag shape on the first surface 4 and a plurality of first concave portions 26 are arranged in a zigzag shape. A plurality of second convex portions 34 are arranged in a zigzag shape on the second surface 6 and a plurality of second concave portions 36 are arranged in a zigzag shape. The first convex portion 24 and the second concave portion 36 are arranged in-and-out one on the other. The second convex portion 34 and the first recessed portion 26 are located one on the inside and one outside. The first convex portion 24 and the second convex portion 34 all have a triangular frustum shape.

In the hollow structure of the first embodiment, the inclination? Of the side surfaces of the first and second convex portions 24 and 34 is in the range of 6.0 to 45.0 [deg.], And the adhesive area ratio on both sides in the thickness direction D1 is And more preferably in the range of 14 to 40 [%]. By setting the inclination? And the bonding area ratio as described above, better results can be obtained from experimental results such as compressive strength, bending strength and bending stiffness.

The inclination θ of the side surfaces of the first and second convex portions 24 and 34 is all in the range of 20 to 25 ° and the adhesive area ratio on both sides of the thickness direction D1 is in the range of 20 to 26% Is more preferable. By setting the inclination? Or the bonding area ratio as described above, more favorable results can be obtained from experimental results such as compressive strength, bending strength and bending stiffness.

It is preferable that the cell size CS of the first convex portion 24 and the second convex portion 34 in the hollow structure of the first embodiment is in the range of 5.0 to 15.0 [mm]. It is more preferable that the cell size CS of the first convex portion 24 and the second convex portion 34 is all in the range of 8.0 to 10.0 [mm].

The cell size CS of the first convex portion 24 is a dimension between two parallel sides of each cell 60 in which the first surface 4 is divided into a honeycomb shape and the cell size CS of the second convex portion 34 is the second Is a dimension between two parallel sides of each cell 60 divided into honeycomb faces. The first convex portion 24 is located one-to-one within the cell 60 of the first side 4. The second convex portion 34 is located one-to-one within the cell 60 of the second surface 6.

In the hollow structure of the first embodiment, the thickness of the core material 2 is within a range of 3 to 30 mm. In the hollow structure of the first embodiment, the core material 2 is made of polypropylene. Therefore, the hollow structure of the first embodiment can be made lighter overall while securing the compressive strength, the bending strength, the bending rigidity and the like.

In the hollow structure of the first embodiment, the compressive strength is in the range of 0.35 to 0.45 [Mpa], the bending strength is in the range of 17.2 to 23.7 [Nm / m] and the bending stiffness is 4.8 to 6.6 [Nm ² / Lt; / RTI >

 In the hollow structure of the first embodiment, the first convex portion 24 and the second convex portion 34 of the core material 2 are formed by vacuum molding a sheet made of a synthetic resin using the mold 16, will be. Therefore, by continuously feeding the sheet, it is possible to continuously form the core material 2 having a predetermined concavo-convex shape.

The mold 16 may be formed by thermoforming a sheet made of a synthetic resin. Therefore, a structure for performing, for example, vacuum pneumatic co-forming, press forming or the like can also be employed as a structure for molding the core material 2. [

The first structure that can be embodied specifically includes, for example, a vacuum forming roll having a mold 16 and a forming roll symmetrical to the vacuum forming roll, and assisted with the forming roll.

The second structure that can be employed is a structure having a forming roll having the mold 16 and another forming roll symmetrical to the forming roll and assisting the forming with the other forming roll. A third structure that can be employed is a structure for performing molding in a vacuum-formed flat plate having the mold 16. The fourth structure that can be adopted is a structure having a vacuum-formed flat plate having the mold 16 and a flat plate symmetrical to the vacuum-formed flat pipe, and assisting the molding in the flat plate. Other structures can of course be employed.

In the method of manufacturing the hollow structure of the first embodiment, vacuum molding is performed on a core sheet made of a synthetic resin using a mold 16 in which a plurality of recesses 18 for vacuum suction are arranged in a zigzag shape, A step of forming a core material 2 made of a synthetic resin on the first side in the thickness direction D1 of the core material 2 and a step of forming a core material 2 having a thickness A step of adhering the first sheet 8 made of synthetic resin to the first side of the direction D1 and a step of adhering the second sheet 10 made of synthetic resin to the second side in the thickness direction D2 of the core material 2 . The step of adhering the first sheet 8 and the step of adhering the second sheet 10 may be performed at different times or at the same time.

The concave portion 18 has a bottom surface of a polygonal shape (triangular shape in the first embodiment), and a suction hole 20 for vacuum suction is provided at a central portion of the bottom surface or near the apex of the apex.

According to the above-described manufacturing method, the core material 2 having the first and second convex portions 24 and 34 as in the first embodiment can be efficiently formed.

While the present invention has been described based on the embodiments shown in the accompanying drawings, it is to be understood that the present invention is not limited to the above-described embodiments, but various modifications and changes may be made without departing from the scope of the present invention. It is possible to apply.

For example, in the embodiment of the present invention, the shape of the first convex portion 24 and the second convex portion 34 is formed of a triangular frustum, but the present invention is not limited thereto, and the shape of the other convex frustum, Shape or a truncated-truncated cone shape may be adopted. Or the shape of the first convex portion 24 or the second convex portion 34 may be a polygonal truncated cone shape having a curved side surface or a polygonal truncated cone shape and a side surface formed in a stepped shape, And a shape in which the side surface is formed in a step shape can be adopted.

The top surface of the first recessed portion 26, the top surface of the second recessed portion 34, and the bottom surface of the second recessed portion 36, Any dimension shape is provided in the same equilateral triangle shape, but it is also possible to form it into a somewhat different dimension shape. The top surface of the convex portion 22 of the mold 16 for molding the core material 2 and the bottom surface of the concave portion 18 are not limited to the equilateral triangle having the same dimensional shape, It is also possible.

In the embodiment of the present invention, the suction holes 20 are formed on the bottom surfaces of the recessed portions 18 so that the recessed portions 18 function as suction cavities. However, by combining a plurality of the molds, And vacuum suction is performed in a gap between a plurality of the molds.

Claims (8)

A core made of a synthetic resin having irregularities in the thickness direction;
A first sheet made of synthetic resin covering the first side of the core material in the thickness direction; And
And a second sheet made of synthetic resin covering the second side of the core material in the thickness direction,
Wherein the core material includes a plurality of frustoconical or bar-shaped first convex portions projecting to the first side in the thickness direction in a zigzag manner in plan view, and a frustum shape or a bar protruding to the second side in the thickness direction Wherein a plurality of second convex portions are arranged in a zigzag shape in plan view. The method according to claim 1,
Wherein the core has a first surface facing the first side in the thickness direction and a second surface facing the second side in the thickness direction,
A plurality of first convex portions are arranged in a zigzag shape on the first surface, a plurality of first concave portions are arranged in a zigzag shape,
A plurality of second convex portions are arranged in a zigzag shape on the second surface, a plurality of second concave portions are arranged in a zigzag shape,
The first convex portion and the second concave portion are located one on the inside and one outside,
Wherein the second convex portion and the first concave portion are located one on the inside and one outside. 3. The method according to claim 1 or 2,
Wherein the first convex portion and the second convex portion are both triangular frustum-shaped bodies. 4. The method according to any one of claims 1 to 3,
Wherein the inclination of the side faces of the first and second convex portions is in the range of 6.0 to 45.0 占 and the bonding area ratio is in the range of 1 to 46%. 5. The method of claim 4,
Wherein the inclination of the side surfaces of the first and second convex portions is in the range of 15.0 to 30.0 占 and the bonded area ratio is in the range of 14 to 40%. 6. The method according to any one of claims 1 to 5,
Wherein the core material is polypropylene. 7. The method according to any one of claims 1 to 6,
Wherein the material of the core material, the material of the first sheet, and the material of the second sheet are the same. Vacuum molding a core sheet made of a synthetic resin using a mold in which a plurality of recesses for vacuum suction are arranged in a zigzag shape to form a core made of a synthetic resin having unevenness in the thickness direction;
A step of adhering a first sheet made of a synthetic resin to the first side of the core material in the thickness direction; And,
And a step of bonding a second sheet made of synthetic resin to the second side of the core material in the thickness direction,
Wherein the concave portion has a polygonal bottom surface and a suction hole for vacuum suction is provided at a central portion of the bottom surface or in the vicinity of the vertex.

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