Resin honeycomb molded body, method for producing same, and mold

Abstract

The present invention provides a resin honeycomb molded body integrally molded by using a resin material, in which a partition wall is easily buckled when receiving a shock and shock absorption can be enhanced.　The resin honeycomb molded body according to the present invention comprises: a plate-like part that is composed of a resin material and has a main surface; and a partition wall that is provided so as to extend from the main surface of the plate-like part in a direction intersecting the main surface and defines a plurality of cylindrical cells. The resin honeycomb molded body is characterized in that: the partition wall has a first surface and a second surface facing each other; at least one of the first surface and the second surface has two types of surfaces having different inclination angles with respect to a direction perpendicular to the main surface; and an inclination angle θ1 of a surface positioned on a side closer to the main surface is larger than an inclination angle θ2 of a surface positioned on a side farther from the main surface.

Description

Resin honeycomb molded body, method for producing the same, and mold

[0001] The present invention relates to a resin honeycomb molded body, a method for producing the same, and a mold.

[0002] Conventionally, honeycomb structures have been widely used as shock absorbing components for automobiles, aircraft and the like because they can reduce weight and improve mechanical strength.

[0003] When a honeycomb structure is made of aluminum or resin, it has been produced, for example, by the following methods. (1) A honeycomb structure is manufactured by sequentially folding members obtained by halving a rectangular tubular member in the height direction. Alternatively, (2) a honeycomb structure is manufactured by arranging a plurality of cylindrical members, applying an adhesive to the side surfaces of the tubular members and joining them together. For example, Patent Document 1 discloses a manufacturing method in which a tubular member made of an aluminum alloy is used to maintain mechanical strength, and the contact surfaces of face plates serving as side walls are brazed and integrated.

[0004] Further, as disclosed in Patent Document 2, when a honeycomb structure is made of metal or thermosetting resin, it has been molded, for example, using a corrugating machine as described below. That is, corrugating gears that are rotationally driven in upper and lower pairs and have irregularities of the same waveform formed at a predetermined pitch on the outer circumference are used. By supplying and passing a strip-shaped foil, a strip-shaped corrugated sheet in which waveform irregularities are continuously bent is obtained. Then, the corrugated sheet obtained by such a corrugating machine and a flat plate are assembled into multiple layers, and the whole is formed into a roll shape, a laminated block shape or the like, and a honeycomb structure having a honeycomb structure is manufactured.

[0005] However, in the method of (1) above, moldable materials are limited, and there are restrictions on the minimum wall thickness and restrictions on material expansion and contraction due to fibers, so fiber-reinforced resin materials cannot be manufactured using the same method. Therefore, compared with a honeycomb structure manufactured from a fiber-reinforced resin material (for example, PPGF: reinforced polypropylene resin containing glass fiber), the shock absorbing capacity is lower, and there is also a problem of cracking

[0006] The method described in (2) above had several problems: the moldable materials were limited; fiber-reinforced resin materials could not be used, as in (1); planar filling was difficult due to the cylindrical shape of the member; and the process was complicated by the need to apply adhesive to the sides of the cylindrical member, as well as the mass increased due to the adhesive.

[0007] These challenges are particularly pronounced in the manufacturing of large-format and large-scale honeycomb structures.

[0008] Therefore, in recent years, a molding method using a mold has also been proposed as a method for manufacturing resin honeycomb structures. In this method, molten resin is injected into a mold having a bottom surface and a plurality of independent hexagonal prism-shaped protrusions that protrude vertically from the bottom surface and are regularly arranged at predetermined intervals. After the resin hardens, the molded product is removed from the mold.

[0009] JP-A-9-156000 JP-A-5-337558

[0010] In the field of mold manufacturing, it is known that a draft angle is provided in the mold to ensure a smooth removal of the hardened resin molded product from the mold without any resin sticking or residue. Such a draft angle is transferred to the molded product, which is a resin honeycomb molded body.

[0011] However, since the draft angle is basically applied from the tip of the partition wall, there was a problem in that it was difficult to predict where the honeycomb molded body would bend when it was subjected to impact and the partition wall deformed by buckling. For example, in terms of the relationship between the thickness and height of the honeycomb partition wall, the height of the partition wall needs to be at least five times its thickness in order for the partition wall to bend once. Therefore, there was a need for a resin honeycomb molded body with a draft angle that would buckle easily when subjected to impact, or in other words, be able to reliably absorb impact.

[0012] This invention has been proposed in view of the above conventional circumstances, and the object of this invention is to provide a resin honeycomb molded body in which the partitions are easily buckled when subjected to impact, thereby enhancing shock absorption, in a honeycomb molded body integrally molded using a resin material. Another object of this invention is to provide a method for manufacturing a resin honeycomb molded body in which the partitions are easily buckled when subjected to impact, thereby enhancing shock absorption, can be manufactured in a simplified process. Furthermore, another object of this invention is to provide a mold used in manufacturing a resin honeycomb molded body in which the partitions are easily buckled when subjected to impact, thereby enhancing shock absorption.

[0013] The problems described above are achieved by the present invention as follows: [1] A resin honeycomb molded body comprising: a plate-like portion having a main surface, and a partition wall extending from the main surface of the plate-like portion in a direction intersecting the main surface, defining a plurality of cylindrical cells, wherein the partition wall has a first surface and a second surface facing each other, and at least one of the first surface and the second surface has two types of surfaces with different inclination angles with respect to the direction perpendicular to the main surface, and the inclination angle θ1 of the surface located closer to the main surface is greater than the inclination angle θ2 of the surface located further away from the main surface. [2] The resin honeycomb molded body according to [1], wherein the first surface and the second surface of the partition wall have different inclination angles. [3] The resin honeycomb molded body according to [1] or [2], wherein the inclination angle θ2 of the surface located further away from the main surface is 2°≧θ2≧0°. [4] The resin honeycomb molded article according to any one of [1] to [3], wherein the ratio of the length H2 of the surface located on the side farther from the main surface to the total length H of the partition wall (H2 / H) is 5% or more and 85% or less. [5] The resin honeycomb molded article according to any one of [1] to [4], wherein, on the surface located on the side farther from the main surface, the ratio of the thickness T of the partition wall to the length H2 of the surface on the side farther from the main surface (T / H2) is 5% or more and 85% or less. [6] The resin honeycomb molded article according to any one of [1] to [5], wherein the partition wall comprises a first partition wall and a second partition wall located further from the center of gravity of the resin honeycomb molded article than the first partition wall, and the largest inclination angle of the second partition wall is greater than the largest inclination angle of the first partition wall. [7] The resin honeycomb molded body according to any one of [1] to [6], wherein the inclination angle of the second surface facing the center of gravity X of the resin honeycomb molded body 1 is larger than the inclination angle of the first surface. [8] The resin honeycomb molded body according to any one of [1] to [7], wherein the shape of the cylindrical cell is a hexagonal prism. [9] The resin honeycomb molded body according to any one of [1] to [8], wherein the plate-like portion and the partition wall are integrally molded.

[10] The resin honeycomb molded body according to any one of [1] to [9], which is plate-like.

[11] The resin honeycomb molded body according to [1] to

[10] , wherein the thickness T of the resin honeycomb molded body is 1 / 10 or less of the maximum external dimension Dmax of the resin honeycomb molded body in a plan view.

[12] The resin honeycomb molded body according to any one of [1] to

[11] , used as an under cover that covers at least a part of the lower surface of a mobile body.

[13] The resin honeycomb molded body according to

[12] , wherein the under cover covers at least a part of the lower surface of a battery provided on the mobile body.

[14] A method for manufacturing a resin honeycomb molded body, comprising a plate-like portion having a main surface and partition walls extending from the main surface of the plate-like portion in a direction intersecting the main surface and defining a plurality of cylindrical cells, comprising the steps of: injecting the resin material into a mold having a bottom surface portion having a main surface and a plurality of independent protrusions that protrude from the main surface of the bottom surface portion in a direction intersecting the main surface and are regularly arranged at predetermined intervals and curing the resin material; and removing the cured resin material from the mold, wherein the protrusions in the mold have a first surface and a second surface facing each other, and at least one of the first surface and the second surface has two types of surfaces with different inclination angles with respect to the direction perpendicular to the main surface, and the inclination angle θ3 of the surface located on the side farther from the main surface is greater than the inclination angle θ4 of the surface located on the side closer to the main surface.

[15] The method for manufacturing a resin honeycomb molded article according to

[14] , wherein the first surface and the second surface of the protruding portion have different inclination angles.

[16] A mold used for manufacturing a resin honeycomb molded body, comprising a plate-like portion having a main surface and partition walls extending from the main surface of the plate-like portion in a direction intersecting the main surface and defining a plurality of cylindrical cells, wherein the mold comprises a bottom surface having a main surface and a plurality of independent protrusions that project from the main surface of the bottom surface in a direction intersecting the main surface and are regularly arranged at predetermined intervals, wherein each protrusion has a first surface and a second surface facing each other, and at least one of the first surface and the second surface has two types of surfaces with different inclination angles with respect to the direction perpendicular to the main surface, characterized in that the inclination angle θ3 of the surface located on the side farther from the main surface is greater than the inclination angle θ4 of the surface located on the side closer to the main surface.

[17] The mold according to

[16] , wherein the first surface and the second surface of the protrusion have different inclination angles.

[18] The mold according to

[16] or

[17] , wherein the surface located on the side closer to the main surface has an inclination angle θ4 of 2° ≥ θ4 ≥ 0°.

[19] The mold according to any one of

[16] to

[18] , wherein the ratio (W / L2) of the width W of the spacing to the length L2 of the surface located on the side closer to the main surface is 5% or more and 85% or less.

[20] The mold according to any one of

[16] to

[19] , wherein the ratio (L2 / L) of the length L2 of the surface located on the side closer to the main surface to the total length L from the bottom surface of the protrusion is 50% or more and 85% or less.

[21] The mold according to any one of

[16] to

[20] , wherein the protrusion comprises a first protrusion and a second protrusion located further from the shrinkage center (molding center) of the resin material than the first protrusion, and the largest inclination angle of the second protrusion is greater than the largest inclination angle of the first protrusion.

[22] The mold according to any one of

[16] to

[21] , wherein the inclination angle of the second surface opposite to the first surface facing the shrinkage center (molding center) Y of the resin material is larger than the inclination angle of the first surface.

[23] The mold according to any one of

[16] to

[22] , wherein the protrusion has a regular hexagonal shape in plan view.

[0014] According to the present invention, it is possible to provide a resin honeycomb molded body in which the partitions are easily buckled when subjected to impact, thereby enhancing shock absorption, in a honeycomb molded body integrally molded using a resin material. Furthermore, according to the present invention, it is possible to provide a method for manufacturing a resin honeycomb molded body in which the partitions are easily buckled when subjected to impact, thereby enhancing shock absorption, using a simplified process. Moreover, according to the present invention, it is possible to provide a mold used in manufacturing a resin honeycomb molded body in which the partitions are easily buckled when subjected to impact, thereby enhancing shock absorption.

[0015] Figure 1 is a longitudinal cross-sectional view showing one example of the honeycomb molded body of the present invention. Figure 2 is a plan view showing one example of the honeycomb molded body of the present invention. Figure 3 is a longitudinal cross-sectional view showing one example of the mold used in the manufacture of the honeycomb molded body. Figure 4 is a plan view showing one example of the mold used in the manufacture of the honeycomb molded body. Figure 5 is a schematic side view of an automobile with a battery and under cover on the bottom surface. Figure 6 is a diagram showing an image of the external dimensions of a resin honeycomb molded body.

[0016] The following describes in detail an exemplary embodiment of the present invention (hereinafter abbreviated as "this embodiment"). The present invention is not limited to this embodiment and can be implemented in various modifications within the scope of its gist. In this specification, the upper and lower limits of each numerical range can be arbitrarily combined.

[0017] [1] Resin honeycomb molded body First, the resin honeycomb molded body of the present invention will be described. Figure 1 is a longitudinal cross-sectional view showing one example of the configuration of the honeycomb molded body of the present invention, and Figure 2 is a plan view showing one example of the configuration of the honeycomb molded body of the present invention. Note that in the drawings, the characteristic parts of the invention may be exaggerated, and the dimensional ratios between the actual components may differ.

[0018] Furthermore, in the following description, the resin honeycomb molded body is described using as an example a case in which it is an aggregate of multiple cells defined in a regular hexagonal shape in plan view. However, the present invention is not limited to this, and also includes aggregates of multiple cells defined in a polygonal shape such as an equilateral triangle or a square in plan view. In addition, it may be a combination of multiple shapes, such as a combination of a regular octagon and a square.

[0019] The resin honeycomb molded body 1 of the present invention is made of a resin material and has a plate-like portion 10 having a main surface 10a, and partition walls 20 that extend from the main surface 10a of the plate-like portion 10 in a direction intersecting the main surface 10a and define a plurality of cylindrical cells 2.

[0020] In the example shown in Figure 1, the partition wall 20 is provided in a direction approximately perpendicular to the main surface 10a of the plate-like portion 10. The portion enclosed by the partition wall 20 becomes a cylindrical cell 2, which in the example shown in Figure 2 forms a regular hexagon in plan view.

[0021] Furthermore, in the resin honeycomb molded body 1 of the present invention, the partition wall 20 has a first surface 201 and a second surface 202 that face each other, and at least one of the first surface 201 and the second surface 202 has two types of surfaces with different inclination angles in the direction perpendicular to the main surface 10a, and the inclination angle θ1 of the surface 20a located closer to the main surface 10a is greater than the inclination angle θ2 of the surface 20b located further away from the main surface 10a (θ1 > θ2 ≥ 0°).

[0022] This allows for the efficient removal of the molded product from the mold 100 after resin curing during manufacturing, and also enables the realization of a resin honeycomb molded body 1 in which the partition walls 20 are more likely to buckle when subjected to impact, thereby enhancing shock absorption. Furthermore, in this resin honeycomb molded body 1, since the tubular cells 2 are filled in a planar manner without the use of adhesive, the mass efficiency and strength efficiency are high, and the increase in mass is suppressed.

[0023] In the example shown in Figure 1, the slope (draft angle) is provided not from the tip of the partition wall 20, but from the middle of the partition wall 20 towards the plate-like portion 10. In other words, the surface 20a on the side closer to the main surface 10a is an inclined surface with an inclination angle θ1. The surface 20b on the side further from the main surface 10a is a vertical surface with an inclination angle θ2 that is substantially 0°, satisfying θ1 > 0° (≒θ2). This makes the partition wall 20 more prone to bending (easier to absorb impact energy) when subjected to impact.

[0024] The example shown in Figure 1 illustrates the case where the inclination angle θ2, which is the angle that surface 20b makes with the normal direction of the main surface 10a, is substantially 0°. However, for manufacturing reasons, the inclination angle θ2 may be greater than 0° (θ2 > 0°). By making the inclination angle θ2 greater than 0°, that is, by making θ1 > θ2 > 0°, the molded product can be more easily removed from the mold 100 after resin curing during manufacturing.

[0025] In the example shown in Figure 1, the case where the inclination angle θ2 of the surface 20b farther from the main surface 10a is substantially 0° was used as an example for explanation, but the present invention is not limited to this, and it is sufficient as long as θ1 > θ2 ≥ 0° is satisfied. The inclination angle θ2 is preferably 2° ≥ θ2 ≥ 0°, more preferably 1.5° ≥ θ2 ≥ 0°, even more preferably 1° ≥ θ2 ≥ 0°, and particularly preferably 1° ≥ θ2 > 0° (however, in all cases θ1 > θ2 is satisfied). For example, if the inclination angle θ1 is 5° ≥ θ1 ≥ 3°, the inclination angle θ2 may be 0.5°.

[0026] The ratio of the length H2 of the surface 20b to the total length H of the partition wall 20 (H2 / H) is not particularly limited, but is preferably 5% to 85%, and more preferably 50% to 70%.

[0027] By making the length H2 of the vertical surface 20b as long as possible, the bulkhead 20 can be made more flexible when subjected to impact (making it easier to absorb the energy of the impact).

[0028] In surface 20b, the ratio (T / H2) of the thickness T of the partition wall 20 to the length H2 of surface 20b is not particularly limited, but is preferably 5% or more and 85% or less, and more preferably 50% or more and 70% or less.

[0029] This makes the partition wall 20 more likely to break when subjected to impact (increasing its ability to absorb impact energy). Here, the thickness T of the partition wall 20 refers to the thickness at the tip of the partition wall 20.

[0030] The partition wall 20 is not limited to having two surfaces with different inclination angles; one or more surfaces with different inclination angles may be arranged between surface 20a and surface 20b.

[0031] In the resin honeycomb molded body 1 of this embodiment, the inclination angles (θ1, θ2) of the first surface 201 and the second surface 202 of the partition wall 20 may be different.

[0032] As described later, in the manufacturing of a resin honeycomb molded body 1 using a mold 100, the shrinkage rate of the resin material differs depending on the position (distance) from the center of the mold 100. By changing the inclination angle of the protrusions 120 (partition walls 20) according to the shrinkage rate of the resin material, the molded product can be removed from the mold 100 after the resin has hardened. In addition, the partition walls 20 can be made more reliably foldable when subjected to impact (to further enhance the absorption of impact energy).

[0033] Specifically, it is preferable to make the inclination angle of the second surface 202 facing the center of gravity X of the resin honeycomb molded body 1 larger than the inclination angle of the first surface 201.

[0034] Note that the center of gravity of the resin honeycomb molded body 1, indicated by X in the figure, is a schematic representation to explain the shrinkage direction of the resin material when viewed from above, and does not accurately represent the actual center of gravity.

[0035] Furthermore, in the resin honeycomb molded body 1 of this embodiment, only one of the two opposing surfaces of the partition wall 20 may be an inclined surface. In this case, it is preferable that the second surface 202 be an inclined surface.

[0036] By providing an inclination on only one side of the partition wall 20, the volume can be reduced compared to the case where both sides of the partition wall 20 are inclined, thereby achieving a lighter resin honeycomb molded body 1. This also contributes to reducing material costs.

[0037] Furthermore, in the resin honeycomb molded body 1, the partition wall 20 comprises a first partition wall 21 and a second partition wall 22 located further from the center of gravity X of the resin honeycomb molded body 1 than the first partition wall 21. Preferably, the largest inclination angle of the second partition wall 22 is greater than the largest inclination angle of the first partition wall 21.

[0038] As described later, the shrinkage rate of the resin material differs depending on the position (distance) from the center of the mold 100, and the inclination angle of the protrusion 120 (corresponding to the partition wall 20) is changed according to the shrinkage rate of the resin material. Specifically, among the partition walls 20, the inclination angle (θ1, θ2) is made relatively small for the first partition wall 21 on the side closer to the center of gravity X of the resin honeycomb molded body 1, where the shrinkage rate of the resin material is relatively small, and the inclination angle (θ1', θ2') is made relatively large for the second partition wall 22 on the side further from the center of gravity X, where the shrinkage rate of the resin material is relatively large. This allows for the efficient removal of the molded product from the mold 100 after the resin has hardened.

[0039] The relationship between the distance from the center of gravity X of the resin honeycomb molded body 1 and the inclination angle of the partition wall 20 may, for example, change linearly in proportion to the distance, change curvilinearly, or have extrema.

[0040] The relationship between the distance from the center of gravity X of the resin honeycomb molded body 1 and the inclination angle of the partition wall 20 can be appropriately selected during the manufacturing of the resin honeycomb molded body 1, depending on the type of resin material and the size of the mold 100 (resin honeycomb molded body 1).

[0041] In such a resin honeycomb molded article 1 of the present invention, for example, when subjected to an external impact, the partition walls 20 undergo buckling deformation, and the buckled partition walls 20 exert the function of dispersing load and expanding the pressure-receiving area. Thereby, when a large load acts as an external force, the propagation to the protected object is dispersed, and the pressure-receiving area is expanded. The load is not propagated as a concentrated load, but is converted into a distributed load and propagated to the protected object. In addition, due to the buckling of the honeycomb partition walls 20, the energy of the load is absorbed, buffered and reduced before being propagated to the protected object.

[0042] In particular, in the resin honeycomb molded article 1 of the present invention, the partition wall 20 has at least two types of inclined surfaces, and the inclination angle θ1 of the surface 20a located on the side closer to the main surface 10a is larger than the inclination angle θ2 of the surface 20b located on the side farther from the main surface 10a (θ1 > θ2), which makes the partition wall 20 prone to buckling when subjected to an impact, improves the absorption of impact energy, and can buffer and reduce the impact.

[0043] [2] Method for Manufacturing Resin Honeycomb Molded Article The resin honeycomb molded article as described above can be manufactured by the manufacturing method shown below. Next, the method for manufacturing the resin honeycomb molded article of the present invention will be described.

[0044] The method for manufacturing a resin honeycomb molded article is a method for manufacturing a resin honeycomb molded article 1 comprising: a plate-shaped portion 10 made of a resin material and having a main surface 10a; and a partition wall 20 provided extending from the main surface 10a of the plate-shaped portion 10 in a direction intersecting the main surface 10a and defining a plurality of cylindrical cells 2, the method comprising: a step (molding step) of injecting the resin material into a mold 100 and curing the resin material, the mold 100 comprising: a bottom portion 110 having a main surface 110a; and a plurality of mutually independent protruding portions 120 protruding from the main surface 110a of the bottom portion 110 in a direction intersecting the main surface 110a and regularly arranged at predetermined intervals (via slits 101); and a step (extraction step) of extracting the cured resin material from the mold 100.

[0045] In the method for manufacturing a resin honeycomb molded body according to the present invention, in the mold 100, the protruding portion 120 has a first surface 1201 and a second surface 1202 that face each other. At least one of the first surface 1201 and the second surface 1202 has two types of surfaces with different inclination angles with respect to a direction perpendicular to the main surface 110a, and the inclination angle θ3 of the surface 120a located on the side farther from the main surface 110a is larger than the inclination angle θ4 of the surface 110b located on the side closer to the main surface 110a (θ3>θ4).

[0046] By integrally molding the plate-shaped portion 10 and the partition walls 20 of the resin honeycomb molded body 1 using the mold 100, the process can be simplified. In particular, the conventional step of applying an adhesive is not required, which enables further simplification of the process and reduction of material costs. In addition, there are few restrictions on materials, and manufacturing with various resins is possible. With such a manufacturing method, it is possible to manufacture the resin honeycomb molded body 1 in which the cylindrical cells 2 are planarly filled without using an adhesive, and which has high mass efficiency and strength efficiency.

[0047] In the method for manufacturing the resin honeycomb molded body 1 according to the present invention, the protruding portion 120 has two types of surfaces with different inclination angles with respect to a direction perpendicular to the main surface 110a as a draft, and by using the mold 100 in which the inclination angle θ3 of the surface 120a located on the side farther from the main surface 110a is larger than the inclination angle θ4 of the surface 120b located on the side closer to the main surface 110a, it is possible to manufacture the resin honeycomb molded body 1 in which the partition walls 20 are likely to buckle when subjected to an impact, and the absorption of impact energy can be enhanced.

[0048] (1) Molding Step In the molding step, a resin material is injected into the mold 100 and cured.

[0049] <Mold> Here, the mold 100 used in the manufacturing of the resin honeycomb molded body 1 according to the present invention will be described. Fig. 3 is a longitudinal cross-sectional view showing one configuration example of a mold used for manufacturing a honeycomb molded body, and Fig. 4 is a plan view showing one configuration example of a mold used for manufacturing a honeycomb molded body.

[0050] The mold 100 has a bottom portion 110 having a main surface 110a, and a plurality of independent protrusions 120 that are provided projecting from the main surface 110a of the bottom portion 110 in a direction intersecting the main surface 110a and are regularly arranged at predetermined intervals (through slits 101).

[0051] In the example shown in Figure 3, the protrusion 120 is provided in a direction approximately perpendicular to the bottom surface 110. Also, in the example shown in Figure 4, the protrusion 120 forms a regular hexagon in plan view.

[0052] Furthermore, in the mold 100 of the present invention, the protruding portion 120 has a first surface 1201 and a second surface 1202 that face each other. At least one of the first surface 1201 and the second surface 1202 has two types of surfaces with different inclination angles in the direction perpendicular to the main surface 110a, and the inclination angle θ3 of the surface 120a located on the side farther from the main surface 110a is greater than the inclination angle θ4 of the surface 120b located on the side closer to the main surface 110a (θ3 > θ4).

[0053] By using such a mold 100, it is possible to manufacture a resin honeycomb molded body 1 in which the partition walls 20 are more likely to buckle when subjected to impact, thereby enhancing the absorption of impact energy. Furthermore, the molded product can be easily removed from the mold 100 after the resin has hardened.

[0054] In the example shown in Figure 3, the inclination (draft angle) of the protrusion 120 of the mold 100 is provided not from the main surface 110a side, but from the middle of the protrusion 120 towards the opening end. In other words, the surface 120a located on the side farther from the main surface 110a is an inclined surface with an inclination angle θ3, and the surface 120b located on the side closer to the main surface 110a is a vertical surface with an inclination angle θ4 that is substantially 0°, satisfying θ3 > 0° (≒θ4).

[0055] The example shown in Figure 3 illustrates the case where the inclination angle θ4 of surface 120b is substantially 0°. However, for manufacturing reasons, θ4 may actually be greater than 0° (θ4 > 0°). The inclination angle θ4 is preferably 2° ≥ θ4 ≥ 0°, more preferably 1.5° ≥ θ4 ≥ 0°, even more preferably 1° ≥ θ4 ≥ 0°, and particularly preferably 1° ≥ θ4 > 0° (however, in all cases, θ3 > θ4 is satisfied). For example, if the inclination angle θ3 is 5° ≥ θ3 ≥ 3°, the inclination angle θ4 may be 0.5°.

[0056] This makes the partition wall 20 more flexible when subjected to impact (making it easier to absorb impact energy), and also allows for more favorable removal of the molded product from the mold 100 after the resin has hardened.

[0057] In the example shown in Figure 3, the case where the inclination angle θ4 of surface 120b is substantially 0° was used as an example for explanation, but the present invention is not limited to this, and it is sufficient as long as θ3 > θ4 ≥ 0° is satisfied.

[0058] The ratio (L2 / L) of the length L2 of the surface 120b closer to the main surface 110a to the total length L of the protruding portion 120 from the bottom surface portion 110 is not particularly limited, but is preferably 50% to 85%, and more preferably 50% to 70%.

[0059] By making the vertical surface 120b as long as possible, it is possible to manufacture a resin honeycomb molded body 1 in which the partition wall 20 is easily broken (easily absorbs impact energy) when subjected to impact.

[0060] The ratio (W / L2) of the width W of the slit 101 to the length L2 of the surface 120b is not particularly limited, but is preferably 5% to 85%, and more preferably 50% to 70%.

[0061] This makes it possible to manufacture a resin honeycomb molded body 1 in which the partition wall 20 is more reliably prone to breaking when subjected to impact (higher impact energy absorption). Here, the width W of the slit 101 refers to the width on the main surface 110a side of the mold 100.

[0062] In the mold 100 of this embodiment, the inclination angles (θ3, θ4) of the first surface 1201 and the second surface 1202 of the protruding portion 120 may be different.

[0063] The resin material filled into the mold 100 shrinks from the periphery of the mold 100 toward the center. Furthermore, the shrinkage rate of the resin material differs depending on its position relative to the shrinkage center (molding center) Y. Specifically, the shrinkage rate is relatively large on the side farther from the shrinkage center and relatively small on the side closer to the shrinkage center.

[0064] Therefore, it is preferable to make the inclination angle of the second surface 1202 of the protruding portion 120 of the mold 100, which is farther from the shrinkage center Y of the resin material and has a relatively large shrinkage rate, and is opposite to the surface facing the shrinkage center Y of the resin material, larger than the inclination angle of the first surface 201.

[0065] By changing the inclination angle of the protrusion 120 in accordance with the shrinkage rate of the resin material, the molded product can be easily removed from the mold 100 after the resin has hardened. Furthermore, it is possible to manufacture a resin honeycomb molded body 1 in which the partition walls 20 are more reliably able to break when subjected to impact (higher impact energy absorption).

[0066] Specifically, it is preferable to make the inclination angle of the second surface 1202, which is opposite to the surface facing the shrinkage center (molding center) Y of the resin material, larger than the inclination angle of the first surface 1201.

[0067] Note that the center of shrinkage (molding center) of the resin material, indicated by Y in the figure, is a schematic representation to explain the direction of shrinkage of the resin material when viewed from above, and does not accurately represent the actual center of gravity.

[0068] Furthermore, the shrinkage center (molding center) Y of the resin material substantially corresponds to the center of gravity X of the resin honeycomb molded body 1 after molding, but it may not be a perfect match.

[0069] Furthermore, in the mold 100, only one of the two opposing surfaces of the projection 120 may have an inclination angle with respect to the vertical. In this case, it is preferable that the second surface 202 is the inclined surface.

[0070] By providing a slope (draft angle) on only one surface of the protrusion 120, it is possible to remove the molded product from the mold 100 after resin curing while reducing the volume and achieving a lighter resin honeycomb molded body 1 compared to the case where both surfaces of the protrusion 120 are sloped. This also contributes to reducing material costs.

[0071] The protrusion 120 comprises a first protrusion 121 and a second protrusion 122 located further from the shrinkage center (molding center) Y of the resin material than the first protrusion 121, and it is preferable that the largest inclination angle of the second protrusion 122 is greater than the largest inclination angle of the first protrusion 121.

[0072] The shrinkage rate of the resin material differs depending on the position (distance) from the center of the mold 100, and the inclination angle of the protrusion 120 is changed according to the shrinkage rate of the resin material. Specifically, of the protrusions 120, the inclination angle (θ3, θ4) is made relatively small for the first protrusion 121 on the side closer to the shrinkage center (molding center) Y, where the shrinkage rate of the resin material is relatively small, and relatively large for the second protrusion 122 on the side further from the shrinkage center (molding center) Y, where the shrinkage rate of the resin material is relatively large. This allows for efficient removal of the molded product from the mold 100 after the resin has hardened.

[0073] The relationship between the distance from the shrinkage center (molding center) Y of the resin material and the inclination angle of the protrusion 120 may, for example, change linearly in proportion to the distance, change curvilinearly, or have extreme values.

[0074] The relationship between the distance from the shrinkage center (molding center) Y of the resin material and the inclination angle of the protrusion 120 can be appropriately selected during the manufacturing of the resin honeycomb molded body 1, depending on the type of resin material and the size of the mold 100 (resin honeycomb molded body 1).

[0075] <Resin Material> The resin material is not particularly limited, but thermoplastic resins can be used. The thermoplastic resin is not particularly limited, and known thermoplastic resins can be applied. The thermoplastic resin may be used alone or in combination of two or more types. Examples of thermoplastic resins include general-purpose plastics, engineering plastics, and super engineering plastics. Examples of thermoplastic resins include polycarbonate resins; polyester resins containing polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate; styrene resins containing polystyrene resin, high-impact polystyrene resin (HIPS), acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-styrene-acrylic rubber copolymer (ASA resin), and acrylonitrile-ethylene propylene rubber-styrene copolymer (AES resin); polyolefin resins containing polyethylene and polypropylene; polyamide resins containing polyamide 6 and polyamide 66; polyimide resins; polyetherimide; polyurethane; polyphenylene ether; polyphenylene sulfide; polysulfone; and acrylic resins containing polymethacrylate. Among these, the resin honeycomb molded body 1 preferably contains a polyolefin resin, and more preferably contains polypropylene, because it has a low specific gravity, which reduces the weight of the resin honeycomb molded body 1, and also has excellent strength, rigidity, and impact resistance. These thermoplastic resins may be derived from fossil fuels, from biomass raw materials, or are mixtures thereof.

[0076] Furthermore, the temperature, pressure, time, etc., during molding are not particularly limited and can be carried out using known methods and conditions appropriate to the resin material.

[0077] (2) Extraction process In the extraction process, the hardened resin material is extracted from the mold 100 to form a resin honeycomb molded body 1.

[0078] Since the protruding portion 120 of the mold 100 has a slope (draft angle) when removing the hardened resin material from the mold 100, the molded product after resin hardening can be removed from the mold 100 without any resin sticking or residue.

[0079] In particular, since a slope is provided only on the second surface 1202 opposite to the surface facing the center of the mold 100 (the shrinkage center Y of the resin material), in accordance with the shrinkage direction and shrinkage rate of the resin material, the molded product can be removed from the mold 100 more smoothly after the resin has hardened.

[0080] Furthermore, in the mold 100, the inclination angle (θ3, θ4) is relatively small at the first protrusion 121, which is close to the shrinkage center Y of the resin material, and relatively large at the second protrusion 122, which is farther from the shrinkage center Y. This allows for more favorable removal of the molded product from the mold 100 after the resin has hardened.

[0081] The shape of the mold 100 described above is substantially transferred to the resin honeycomb molded body 1, which is a resin molded product.

[0082] In the resin honeycomb molded body 1 manufactured in this manner, at least one surface of the partition wall 20 has two types of inclined surfaces with respect to the vertical direction, and the inclination angle θ1 of the surface 20a located closer to the main surface 10a is greater than the inclination angle θ2 of the surface 20b located further away from the main surface 10a. This makes it possible to realize a resin honeycomb molded body 1 in which the partition wall 20 is more likely to buckle when subjected to impact, thereby increasing the ability to absorb impact energy.

[0083] Furthermore, in this resin honeycomb molded body 1, since the tubular cells 2 are filled in a planar manner without using adhesive, the mass efficiency and strength efficiency are high, and the increase in mass is also suppressed.

[0084] <Undercover (cover for mobile vehicle)> The resin honeycomb molded body 1 described above is not particularly limited in its use, but because it is lightweight yet excellent at absorbing impact energy, it is suitably used as an impact absorbing member such as a cover member for a mobile vehicle, and in particular as an undercover placed on the underside of a mobile vehicle.

[0085] On the underside of a moving body, collisions, abrasions, or localized loads are likely to occur due to foreign objects such as flying stones, gravel, and ice chunks from the road surface. When such external forces act, the resin honeycomb molded body 1 has a structure in which the partition walls 20 are easily deformed by buckling, so it can absorb energy while dispersing the external force and mitigate damage to the moving body (vehicle body).

[0086] When the resin honeycomb molded body 1 is used as a cover member to cover an object such as a moving object, it is preferable that the resin honeycomb molded body 1 is plate-shaped overall. By making the resin honeycomb molded body 1 plate-shaped overall, it is possible to increase the area of ​​the covered region while suppressing an increase in weight. It also contributes to reducing the number of members required to cover the same area and to reducing the number of installation steps.

[0087] In this specification, "plate-like" is not limited to those with a flat main surface, but also includes shapes that function as a panel overall, even if the main surface is curved, gently curved, warped, or has localized irregularities.

[0088] In this specification, "mobile body" means a structure or device that can move on land, water, or air, and includes self-propelled devices and those that are towed or transported by other devices, regardless of whether they are powered or not. Specific examples of mobile bodies include, but are not limited to, automobiles, motorcycles, industrial vehicles, railway vehicles, water-based mobile bodies, and air-based mobile bodies.

[0089] More specifically, as shown in Figure 5, when the moving object is an automobile 300, the resin honeycomb molded body 1 is preferably used as an under cover 310 that covers at least a portion of the underside of the automobile 300.

[0090] The under cover 310 may have a structure in which a resin honeycomb molded body 1 is laminated with a resin or metal plate-like member. In this case, the resin honeycomb molded body 1 may be bonded to the plate-like member with an adhesive, or it may be mechanically fastened to the plate-like member. This makes it possible to ensure abrasion resistance and environmental resistance (water, mud, salt damage, etc.) on the surface side, while allowing the internal honeycomb structure to absorb shocks.

[0091] To more significantly enhance the effects described above, it is preferable that the under cover 310 be positioned to cover at least a portion of the underside of the battery of the automobile 300. For example, as shown in Figure 5, it is preferable that the under cover 310 be positioned to cover at least the main part of the BEV (Battery Electric Vehicle) battery 301 mounted on the underside of the automobile 300, and more preferably to cover the entire underside of the battery 301.

[0092] This prevents foreign objects bounced up from the road surface 350 from directly colliding with the battery 301, and even if an impact occurs, the resin honeycomb molded body 1 absorbs the energy, thereby mitigating damage to the battery 301 and the automobile 300.

[0093] When used in the under cover 310, from the viewpoint of thinning and weight reduction, as shown in Figure 6, the thickness T of the resin honeycomb molded body 1 is preferably 1 / 10 or less, more preferably 1 / 20 or less, and more preferably 1 / 50 or less, of the maximum external dimension Dmax of the resin honeycomb molded body 1 in a plan view. In Figure 6, Dmax is the length of the long side of the circumscribing rectangle of the resin honeycomb molded body 1 in a plan view, Dmin is the length of the short side of the circumscribing rectangle, and T is the thickness of the resin honeycomb molded body 1. By suppressing the thickness T in this way, it is possible to achieve thinning and weight reduction of the resin honeycomb molded body 1 and the under cover 310 while maintaining the high impact resistance of the resin honeycomb molded body 1.

[0094] In the resin honeycomb molded body 1, the ratio of the length Dmax of the long side to the thickness T (Dmax / T) is preferably 10 or more, more preferably 20 or more, and even more preferably 50 or more. By setting Dmax / T within the above range, it is easier to secure a wide shock absorption area while suppressing an increase in weight. In addition, since the thickness of the under cover 310 can be reduced, it is easier to suppress an increase in the external dimensions of the mobile body (automobile 300).

[0095] The upper limit of Dmax / T is not particularly limited, but it may be 5000 or less, 4000 or less, 3000 or less, or 2000 or less. Dmax / T is preferably 10 or more and 5000 or less, more preferably 20 or more and 5000 or less, and even more preferably 50 or more and 5000 or less.

[0096] In the resin honeycomb molded body 1, the ratio of the length Dmin of the short side to the thickness T (Dmin / T) is preferably 5 or more, more preferably 10 or more, and even more preferably 25 or more. By setting Dmin / T within the above range, it is easier to secure a wide shock absorption area while suppressing an increase in weight. In addition, since the thickness of the under cover 310 can be reduced, it is easier to suppress an increase in the external dimensions of the mobile body (automobile 300).

[0097] The upper limit of Dmin / T is not particularly limited, but it may be 4000 or less, 3000 or less, 2000 or less, or 1000 or less. Dmax / T is preferably 5 or more and 4000 or less, more preferably 10 or more and 4000 or less, and even more preferably 25 or more and 4000 or less.

[0098] Although Figure 6 shows the resin honeycomb molded body 1 as a rectangular plate in plan view, it is not limited to this, and the planar shape can be set as appropriate according to the shape of the underside of the automobile, the shape of the battery, etc.

[0099] While embodiments of the present invention have been described above, the present invention is not limited thereto and can be modified as appropriate without departing from the spirit of the invention.

[0100] This application is a priority application based on Japanese Patent Application No. 2025-056569, filed on 28 March 2025, and the claims, specification and drawings of said Japanese Patent Application are incorporated herein by reference.

[0101] By using the resin honeycomb molded body according to the present invention, the partition walls are more likely to buckle when subjected to impact, thereby increasing the ability to absorb impact energy. This makes it possible to widely use it as a honeycomb structure in impact-absorbing parts for automobiles, aircraft, and other applications.

[0102] 1: Resin honeycomb molded body, 2: Cylindrical cell, 10: Plate-shaped part, 10a: Main surface, 20: Partition wall, 201: First surface, 202: Second surface, 20a: Surface, 20b: Surface, θ1: Inclination angle, θ2: Inclination angle, 300: Automobile (mobile body), 301: Battery, 310: Under cover, 350: Road surface

Claims

1. A resin honeycomb molded body comprising: a plate-like portion having a main surface; and partition walls extending from the main surface of the plate-like portion in a direction intersecting the main surface, defining a plurality of cylindrical cells, wherein the partition walls have a first surface and a second surface facing each other, and at least one of the first surface and the second surface has two types of surfaces with different inclination angles with respect to the direction perpendicular to the main surface, and the inclination angle θ1 of the surface located closer to the main surface is greater than the inclination angle θ2 of the surface located further away from the main surface.

2. The resin honeycomb molded article according to claim 1, wherein the inclination angles of the first surface and the second surface of the partition wall are different.

3. The resin honeycomb molded article according to claim 1, wherein the inclination angle θ2 of the surface located on the side farther from the main surface is 2° ≥ θ2 ≥ 0°.

4. The resin honeycomb molded article according to claim 1, wherein the ratio of the length H2 of the surface located on the side farther from the main surface to the total length H of the partition wall (H2 / H) is 5% or more and 85% or less.

5. The resin honeycomb molded article according to claim 1, wherein, on the surface located on the side farther from the main surface, the ratio (T / H2) of the thickness T of the partition wall to the length H2 of the surface farther from the main surface is 5% or more and 85% or less.

6. The resin honeycomb molded body according to claim 1, wherein the partition wall comprises a first partition wall and a second partition wall located further from the center of gravity of the resin honeycomb molded body than the first partition wall, and the largest inclination angle of the second partition wall is greater than the largest inclination angle of the first partition wall.

7. The resin honeycomb molded body according to claim 1, wherein the inclination angle of the second surface facing the center of gravity X of the resin honeycomb molded body 1 is larger than the inclination angle of the first surface.

8. The resin honeycomb molded body according to claim 1, wherein the shape of the cylindrical cell is a hexagonal prism shape.

9. The resin honeycomb molded body according to claim 1, wherein the plate-like portion and the partition wall are integrally molded.

10. The resin honeycomb molded body according to claim 1, which is in the shape of a plate.

11. The resin honeycomb molded body according to claim 1, wherein the thickness T of the resin honeycomb molded body is 1 / 10 or less of the maximum external dimension Dmax of the resin honeycomb molded body in a plan view.

12. The resin honeycomb molded body according to claim 1, used as an under cover that covers at least a portion of the lower surface of a moving body.

13. The resin honeycomb molded body according to claim 11, wherein the under cover covers at least a portion of the lower surface of the battery provided on the mobile body.

14. A method for manufacturing a resin honeycomb molded body, comprising a plate-like portion having a main surface and partition walls extending from the main surface of the plate-like portion in a direction intersecting the main surface and defining a plurality of cylindrical cells, comprising the steps of: injecting the resin material into a mold having a bottom surface portion having a main surface and a plurality of independent protrusions that project from the main surface of the bottom surface portion in a direction intersecting the main surface and are regularly arranged at predetermined intervals and curing the resin material; and removing the cured resin material from the mold, wherein the protrusions in the mold have a first surface and a second surface facing each other, and at least one of the first surface and the second surface has two types of surfaces with different inclination angles with respect to the direction perpendicular to the main surface, and the inclination angle θ3 of the surface located on the side farther from the main surface is greater than the inclination angle θ4 of the surface located on the side closer to the main surface.

15. The method for manufacturing a resin honeycomb molded article according to claim 14, wherein the inclination angles of the first surface and the second surface of the protruding portion are different.

16. A mold used for manufacturing a resin honeycomb molded body, comprising a plate-like portion having a main surface and partition walls extending from the main surface of the plate-like portion in a direction intersecting the main surface and defining a plurality of cylindrical cells, wherein the mold comprises a bottom surface having a main surface and a plurality of independent protrusions protruding from the main surface of the bottom surface in a direction intersecting the main surface and regularly arranged at predetermined intervals, wherein each protrusion has a first surface and a second surface facing each other, and at least one of the first surface and the second surface has two types of surfaces with different inclination angles with respect to the direction perpendicular to the main surface, characterized in that the inclination angle θ3 of the surface located on the side farther from the main surface is greater than the inclination angle θ4 of the surface located on the side closer to the main surface.

17. The mold according to claim 16, wherein the first surface and the second surface of the protruding portion have different inclination angles.

18. The mold according to claim 16, wherein the surface located on the side closer to the main surface has an inclination angle θ4 of 2° ≥ θ4 ≥ 0°.

19. The mold according to claim 16, wherein, on the surface located closer to the main surface, the ratio (W / L2) of the width W of the spacing to the length L2 of the surface located closer to the main surface is 5% or more and 85% or less.

20. The mold according to claim 16, wherein the ratio of the length L2 of the surface located on the side closer to the main surface to the total length L of the protruding portion from the bottom surface (L2 / L) is 50% or more and 85% or less.

21. The mold according to claim 16, wherein the protrusion comprises a first protrusion and a second protrusion located further from the shrinkage center (molding center) of the resin material than the first protrusion, and the largest inclination angle of the second protrusion is greater than the largest inclination angle of the first protrusion.

22. The mold according to claim 16, wherein the inclination angle of the second surface opposite to the first surface facing the shrinkage center (molding center) Y of the resin material is larger than the inclination angle of the first surface.

23. The mold according to claim 16, wherein the protruding portion has a regular hexagonal shape in plan view.

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