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

Abstract

Provided is a resin honeycomb molded body capable of achieving weight reduction while securing good releasability from a molding die.　This resin honeycomb molded body is composed of a resin material, and comprises: a plate-shaped part having a main surface; and a partition wall provided so as to extend from the main surface of the plate-shaped part in a direction intersecting the main surface, and defining a plurality of tubular cells. The resin honeycomb molded body is characterized in that the partition wall has a first surface and a second surface opposing each other, and when an angle formed by the first surface and a normal direction of the main surface is defined as an inclination angle θ1, and an angle formed by the second surface and the normal direction of the main surface is defined as an inclination angle θ2, the inclination angle θ2 is larger than the inclination angle θ1 (θ2 > θ1 ≥ 0°).

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 achieve weight reduction and improved mechanical strength.

[0003] When a honeycomb structure is made of aluminum or resin, it has conventionally 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 cylindrical members and joining them together. For example, Patent Document 1 discloses a manufacturing method in which a cylindrical member made of an aluminum alloy is used to maintain mechanical strength, and the abutting surfaces of face plates serving as side walls are brazed to be integrated.

[0004] Further, as disclosed in Patent Document 2, when a honeycomb structure is made of metal or thermosetting resin, it has conventionally been molded using, for example, the following corrugating machine. Specifically, 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 periphery are used. By supplying and passing a strip-shaped foil through the machine, a strip-shaped corrugated plate in which corrugated irregularities are continuously bent and formed is obtained. Then, the corrugated plate obtained by such a corrugating machine and a flat plate are assembled in multiple layers, and the whole forms 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 absorption 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 are provided to protrude from the bottom surface in a direction intersecting it 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] Typically, draft angles are uniformly set at the same angle for identical product shapes. Therefore, when applying draft angles to a mold for manufacturing a resin honeycomb molded product using the usual draft angle design philosophy, the same draft angle is applied uniformly to all sides of the hexagonal prism-shaped protrusions. This leads to the problem that the volume of the resin honeycomb molded product increases by the amount of the draft angle, resulting in an increase in the overall weight of the molded product.

[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 article that can achieve weight reduction while ensuring good releaseability from the molding die. Another object of this invention is to provide a method for manufacturing a resin honeycomb molded article that can produce a resin honeycomb molded article that can achieve weight reduction while ensuring good releaseability from the molding die in a simplified process. Furthermore, another object of this invention is to provide a mold used in the manufacture of a resin honeycomb molded article that can achieve weight reduction while ensuring good releaseability from the molding die.

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

[10] The resin honeycomb molded article according to any one of [1] to [9], wherein the plate-like portion and the partition wall are integrally molded.

[11] A resin honeycomb molded body according to any one of [1] to

[10] , which is in the shape of a plate.

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

[11] , 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.

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

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

[14] The resin honeycomb molded body according to

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

[15] 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, defining a plurality of cylindrical cells, the method comprising: injecting the resin material into a mold having a bottom surface portion having a main surface; and a plurality of independent protrusions extending from the main surface of the bottom surface portion in a direction intersecting the main surface, and regularly arranged at predetermined intervals, and curing the resin material; and removing the cured resin material from the mold, wherein the mold has a first surface and a second surface facing each other, and the inclination angle θ4, which is the angle the second surface makes with the normal direction of the main surface, is greater than the inclination angle θ3, which is the angle the first surface makes with the normal direction of the main surface.

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

[15] , wherein in the mold, the second surface of the pin is the surface opposite to the surface facing the shrinkage center of the resin material.

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

[15] or

[16] , wherein the inclination angle θ3 is θ3 > 0°.

[18] The method for manufacturing a resin honeycomb molded article according to any one of

[15] to

[17] , wherein in the mold, the protrusion comprises a first protrusion and a second protrusion located further from the shrinkage 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.

[19] The method for manufacturing a resin honeycomb molded article according to any one of

[15] to

[18] , wherein the inclination angle θ3 is 2° ≥ θ3 ≥ 0°.

[20] A method for manufacturing a resin honeycomb molded article according to any one of

[15] to

[19] , wherein the shape of the cylindrical cell is a hexagonal prism.

[21] A method for manufacturing a resin honeycomb molded article according to any one of

[15] to

[20] , wherein the plate-like portion and the partition wall are integrally molded.

[22] A mold used for manufacturing a resin honeycomb molded body, comprising a resin material, 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 mold comprises a bottom surface having a main surface, and a plurality of independent protrusions extending from the main surface of the bottom surface in a direction intersecting the main surface, and regularly arranged at predetermined intervals, wherein the protrusions have a first surface and a second surface facing each other, and the inclination angle θ4, which is the angle the second surface makes with the normal direction of the main surface, is greater than the inclination angle θ3, which is the angle the first surface makes with the normal direction of the main surface (θ4 > θ3 ≥ 0°).

[23] The mold according to

[22] , wherein the second surface of the protrusion is the surface opposite to the surface facing the shrinkage center of the resin material.

[24] The mold according to

[22] or

[23] , wherein the inclination angle θ3 is θ3 > 0°.

[25] The mold according to any one of

[22] to

[24] , wherein the protrusion comprises a first protrusion and a second protrusion located further from the shrinkage 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.

[26] The mold according to any one of

[22] to

[25] , wherein the inclination angle θ3 is 2°≧θ3≧0°.

[27] The mold according to any one of

[22] to

[27] , wherein at least one of the first surface and the second surface of the protrusion has two types of surfaces with different inclination angles in the direction perpendicular to the main surface, and the inclination angle of the surface located further from the main surface is greater than the inclination angle of the surface located closer to the main surface.

[28] The mold according to

[27] , wherein the ratio of the length of the surface located closer to the main surface to the total length of the partition wall is 5% or more and 85% or less.

[29] The mold according to

[27] or

[28] , wherein, on the surface located closer to the main surface, the ratio of the thickness of the partition wall to the length of the surface closer to the main surface is 5% or more and 85% or less.

[30] The mold according to any one of

[22] to

[29] , wherein the protruding portion has a regular hexagonal shape in plan view.

[0014] According to the present invention, it is possible to provide a resin honeycomb molded article that can achieve weight reduction while ensuring good release properties from the molding die. Furthermore, according to the present invention, it is possible to provide a method for manufacturing a resin honeycomb molded article that can achieve weight reduction while ensuring good release properties from the molding die, using a simplified process. Moreover, according to the present invention, it is possible to provide a mold used in the manufacture of a resin honeycomb molded article that can achieve weight reduction while ensuring good release properties from the molding die.

[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.

[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 given as an example of 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 provided in a direction intersecting the main surface 10a of the plate-like portion 10, defining 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, the resin honeycomb molded body 1 of the present invention has a partition wall 20 having a first surface 20a and a second surface 20b that face each other. When the angle between the first surface 20a and the normal direction of the main surface 10a is defined as the inclination angle θ1, and the angle between the second surface 20b and the normal direction of the main surface 10a is defined as the inclination angle θ2, the inclination angle θ2 is greater than the inclination angle θ1 (θ2 > θ1 ≥ 0°). Here, the inclination angle θ1 is preferably 2° ≥ θ1 ≥ 0°, more preferably 1.5° ≥ θ1 ≥ 0°, even more preferably 1° ≥ θ1 ≥ 0°, and particularly preferably 1° ≥ θ1 > 0° (however, in all cases, θ2 > θ1 is satisfied). For example, if the inclination angle θ2 is 5° ≥ θ2 ≥ 3°, the inclination angle θ1 may be 0.5°.

[0022] In the example shown in Figure 1, the inclination angle θ1, which is the angle that the first surface 20a makes with the normal direction of the main surface 10a, is substantially 0°. However, for manufacturing reasons, the inclination angle θ1 may actually be greater than 0° (θ1 > 0°). By making the inclination angle θ1 greater than 0°, that is, by making θ2 > θ1 > 0°, the molded product can be more easily removed from the mold 100 after the resin has hardened during manufacturing.

[0023] In this embodiment, by providing a relatively large incline on only one surface of the partition wall 20, the volume can be reduced compared to the case where both surfaces of the partition wall 20 are inclined, thereby achieving a lighter resin honeycomb molded body 1. This also contributes to reducing material costs. Furthermore, in this resin honeycomb molded body 1, since the tubular cells 2 are filled in a planar structure without the use of adhesive, the mass efficiency and strength efficiency are high, and the increase in mass is suppressed.

[0024] As will be described later, in the production of the resin honeycomb molded body 1 using the mold 100, the resin material shrinks from the periphery of the mold 100 toward the center, and the shrinkage rate of the resin material increases as it moves away from the center of the mold 100.

[0025] Therefore, as shown in Figure 2, by increasing the inclination of the second surface 20b of the partition wall 20, which is the side facing the center of gravity of the resin honeycomb molded body 1 (indicated by X in the figure) and is in the direction in which the resin material shrinks, the molded product after resin curing can be removed from the mold 100 more efficiently.

[0026] 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.

[0027] 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.

[0028] 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 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 (θ1', θ2' > θ2). This allows for the smooth removal of the molded product from the mold 100 after the resin has hardened.

[0029] 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, or it may change curvilinearly. It may also have extrema.

[0030] 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).

[0031] Furthermore, the partition wall 20 may have two inclined surfaces with different inclination angles. For example, the partition wall 20 may have at least one of its two opposing surfaces, a first surface 20a and a second surface 20b, each having two surfaces with different inclination angles relative to the main surface 10a, and the inclination angle of the surface closer to the main surface 10a may be greater than the inclination angle of the surface further away from the main surface 10a. In this case, the partition wall 20 includes multiple surfaces with different inclination angles, and the inclination angle of the surface with the largest inclination angle is defined as inclination angle θ1 or inclination angle θ2.

[0032] The ratio of the length of the side of the partition wall 20 that is farther from the main surface 10a to the total length of the partition wall 20 is not particularly limited, but is preferably 5% to 85%, and more preferably 50% to 70%.

[0033] By making the length of the side furthest from the main surface 10a as long as possible, the partition wall 20 can be made more prone to bending (more easily absorbs impact energy) when subjected to impact.

[0034] On the side of the wall furthest from the main surface 10a, the ratio of the thickness of the partition wall 20 to the length of the side of the wall furthest from the main surface 10a is not particularly limited, but is preferably 5% to 85%, and more preferably 50% to 70%.

[0035] This makes the partition wall 20 more reliably foldable 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.

[0036] This allows for efficient removal from the mold 100, and enables the realization of a resin honeycomb molded body 1 in which the partition walls 20 buckle easily when subjected to impact, thereby reliably absorbing the impact (energy).

[0037] In the resin honeycomb molded body 1 of the present invention, for example, when subjected to an external impact, the partition walls 20 buckle and deform, and the buckled partition walls 20 exhibit load distribution and pressure-receiving area expansion functions. As a result, when a large load is applied as an external force, the transmission to the protected object is dispersed and the pressure-receiving area is expanded. The load is not transmitted as a concentrated load, but is transmitted to the protected object as a distributed load. In addition, due to the buckling of the honeycomb partition walls 20, the load's energy is absorbed, buffered, and reduced before being transmitted to the protected object.

[0038] [2] Method for Manufacturing a Resin Honeycomb Molded Body The resin honeycomb molded body described above can be manufactured by the manufacturing method shown below. Next, the method for manufacturing a resin honeycomb molded body of the present invention will be described. Figure 3 is a vertical cross-sectional view showing an example of the configuration of a mold used in the manufacture of a honeycomb molded body, and Figure 4 is a plan view showing an example of the configuration of a mold used in the manufacture of a honeycomb molded body.

[0039] The present invention provides a method for manufacturing a resin honeycomb molded body, comprising the steps of: injecting a resin material into a mold 100 having a bottom portion 110 having a main surface 110a, and a plurality of independent protrusions 120 that are provided protruding from the main surface 110a of the bottom portion 110 in a direction intersecting the main surface 110a and arranged regularly at predetermined intervals, and curing the resin material (molding step); and removing the cured resin material from the mold 100 (removal step).

[0040] Furthermore, in the method for manufacturing a resin honeycomb molded article of the present invention, the mold 100 has a protruding portion 120 having a first surface 120a and a second surface 120b that face each other. The method is characterized in that when the angle between the first surface 120a and the normal direction of the main surface 110a is the inclination angle θ3, and the angle between the second surface 120b and the normal direction of the main surface 110a is the inclination angle θ4, then θ4 is greater than θ3 (θ4 > θ3 ≥ 0°).

[0041] By integrally molding the plate-shaped portion 10 and the partition wall 20 of the resin honeycomb molded body 1 using the mold 100, the process can be simplified. In particular, the conventional process of applying adhesive is eliminated, further simplifying the process and reducing material costs. Furthermore, there are fewer material restrictions, and it is possible to manufacture with various resins. In this manufacturing method, the cylindrical cells 2 are filled in a planar manner without the use of adhesive, and a resin honeycomb molded body 1 with high mass efficiency and strength efficiency can be manufactured.

[0042] Furthermore, in the manufacturing method of the resin honeycomb molded body 1 of this embodiment, by using a mold 100 in which a draft angle is provided as an inclination on only one of the two opposing surfaces of the protruding portion 120, the volume can be reduced compared to the case where both surfaces of the protruding portion 120 are inclined surfaces, thereby achieving further weight reduction of the resin honeycomb molded body 1. This also contributes to further reduction of material costs.

[0043] (1) Molding process: In the molding process, resin material is injected into the mold 100 and cured.

[0044] <Mold> Here, the mold of the present invention used for producing a resin honeycomb molded body will be described. This mold 100 is a mold used for producing a resin honeycomb molded body 1, wherein the resin honeycomb molded body 1 is composed of a resin material and includes a plate-shaped portion 10 having a main surface 10a, and partition walls 20 provided to extend in a direction intersecting from the plate-shaped portion 10 and defining a plurality of cylindrical cells 2. The mold 100 includes a bottom surface portion 110 having a main surface 110a, and a plurality of mutually independent protruding portions 120 provided to protrude from the main surface 110a of the bottom surface portion 110 in a direction intersecting the main surface 110a and regularly arranged at predetermined intervals (via slits 101).

[0045] In the example shown in FIG. 3, the protruding portions 120 are provided in a direction substantially perpendicular to the bottom surface portion 110. Furthermore, in the example shown in FIG. 4, the protruding portions 120 form a regular hexagon in a plan view.

[0046] In the mold 100 of the present invention, each protruding portion 120 has a first surface 120a and a second surface 120b that face each other. When an angle formed by the first surface 120a and the normal direction of the main surface 110a is defined as an inclination angle θ3, and an angle formed by the second surface 120b and the normal direction of the main surface 110a is defined as an inclination angle θ4, the mold is characterized in that the inclination angle θ4 is larger than the inclination angle θ3 (θ4 > θ3 ≧ 0°). Here, it is preferable that 2° ≧ θ3 ≧ 0°, more preferably 1.5° ≧ θ3 ≧ 0°, still more preferably 1° ≧ θ3 ≧ 0°, and particularly preferably 1° ≧ θ3 > 0° (provided that θ4 > θ3 is satisfied in any case). For example, the inclination angle θ3 may be 0.5°.

[0047] In the example shown in FIG. 3, a case where the inclination angle θ3 formed by the first surface 120a and the normal direction of the main surface 110a is substantially 0° is shown. Note that, for manufacturing reasons, the inclination angle θ3 is actually not 0° but has a slight angle (θ3 > 0°).

[0048] By providing an inclination (draft) only on one of the two mutually opposing surfaces of the protruding portion 120, it is possible to suitably extract the molded article after resin curing from the mold 100, and achieve weight reduction of the resin honeycomb molded body 1 by reducing the volume compared to the case where both surfaces of the protruding portion 120 are inclined surfaces. This also contributes to the reduction of material costs.

[0049] The resin material filled into the mold 100 shrinks from the peripheral edge portion of the mold 100 toward the center direction. Further, the shrinkage rate of the resin material varies depending on the position from the shrinkage center (molding center) Y of the resin material. Specifically, the shrinkage rate is relatively large on the side far from the shrinkage center, and relatively small on the side close to the shrinkage center.

[0050] Therefore, as shown in Fig. 4, among the protruding portions 120 of the mold 100, by increasing the inclination of the surface on the side far from the shrinkage center Y of the resin material and having a relatively large shrinkage rate, specifically, the inclination of the second surface 120b on the opposite side to the surface facing the shrinkage center Y of the resin material, the molded article after resin curing can be more suitably extracted from the mold 100.

[0051] It should be noted that the shrinkage center (molding center) of the resin material indicated by Y in the drawings is schematically shown for explaining the shrinkage direction of the resin material in a plan view, and does not accurately indicate the actual center position.

[0052] Further, after molding, 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, but may not completely coincide therewith.

[0053] The protruding portion 120 includes a first protruding portion 121 and a second protruding portion 122 located farther than the first protruding portion 121 from the shrinkage center (molding center) Y of the resin material, and it is preferable that the maximum inclination angle of the second protruding portion 122 is larger than the maximum inclination angle of the first protruding portion 121.

[0054] 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, 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 (θ3', θ4' > θ4). This allows for efficient removal of the molded product from the mold 100 after the resin has hardened.

[0055] 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, or it may change curvilinearly. It may also have extreme values.

[0056] 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).

[0057] Furthermore, the projection 120 may have two inclined surfaces with different inclination angles. For example, the projection 120 may have at least one of its two opposing surfaces, a first surface 120a and a second surface 120b, each having two surfaces with different inclination angles relative to the main surface 110a, and the inclination angle of the surface located further from the main surface 110a may be greater than the inclination angle of the surface located closer to the main surface 110a. In this case, if the projection 120 includes multiple surfaces with different inclination angles, the inclination angle of the surface with the largest inclination angle shall be defined as inclination angle θ3 or inclination angle θ4.

[0058] The ratio of the length of the surface closer to the main surface 110a to the total length of the protrusion 120 is not particularly limited, but is preferably 5% to 85%, and more preferably 50% to 70%.

[0059] By making the length of the side closest to the main surface 110a as long as possible, it is possible to manufacture a resin honeycomb molded body 1 in which the partition wall 20 is more likely to break when subjected to impact (more likely to absorb impact energy).

[0060] The ratio of the width of the slit 101 to the length of the surface on the side closer to the main surface 110a 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 of the slit 101 refers to the width on the main surface 110a side of the mold 100.

[0062] <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.

[0063] 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.

[0064] (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.

[0065] Since the protruding portion 120 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.

[0066] In particular, the inclination of the second surface 120b, which is opposite to the surface facing the center of the mold 100 (the shrinkage center Y of the resin material), is increased in accordance with the shrinkage direction and shrinkage rate of the resin material, so that the molded product can be removed from the mold 100 more smoothly after the resin has hardened.

[0067] Furthermore, in the mold 100, the inclination angle 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.

[0068] The shape of the mold 100 described above is substantially transferred to the resin honeycomb molded body 1, which is a resin molded product.

[0069] In the resin honeycomb molded body 1 manufactured in this manner, the volume can be reduced and the weight reduced compared to when both sides are sloped, because only one side (the second side 20b) of the partition wall 20 is sloped.

[0070] 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.

[0071] <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.

[0072] 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).

[0073] 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 components required to cover the same area and to reducing the number of installation steps.

[0074] In this specification, "plate-like" is not limited to those with a flat main surface, but also includes shapes that are flat overall and function as a panel, even if the main surface is curved, gently curved, warped, or has localized irregularities.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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 301 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.

[0079] 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.

[0080] 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.

[0081] 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).

[0082] 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.

[0083] 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).

[0084] 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.

[0085] 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.

[0086] This application is a priority application claiming based on Japanese Patent Application No. 2025-056497, filed on 28 March 2025, and the claims, specification and drawings of said Japanese Patent Application are incorporated herein by reference.

[0087] 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.

[0088] By using the resin honeycomb molded body according to the present invention, it is possible to reduce the volume and lighten the weight, making it widely usable as a honeycomb structure in shock-absorbing parts for automobiles, aircraft, and other applications.

[0089] 1: Resin honeycomb molded body, 2: Cylindrical cell, 10: Plate-shaped part, 10a: Main surface, 20: Partition wall, 20a: First surface, 20b: Second 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 when the angle between the first surface and the normal direction of the main surface is defined as the inclination angle θ1, and the angle between the second surface and the normal direction of the main surface is defined as the inclination angle θ2, the inclination angle θ2 is greater than the inclination angle θ1 (θ2 > θ1 ≥ 0°).

2. The resin honeycomb molded body according to claim 1, wherein the second surface of the partition wall is the surface facing the center of gravity of the resin honeycomb molded body.

3. The resin honeycomb molded article according to claim 1 or 2, wherein the inclination angle θ1 is θ1 > 0°.

4. The resin honeycomb molded body according to claim 1 or 2, 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.

5. The resin honeycomb molded article according to claim 1 or 2, wherein the inclination angle θ1 is 2° ≥ θ1 ≥ 0°.

6. The resin honeycomb molded article according to claim 1 or 2, wherein at least one of the first surface and the second surface of the partition wall has two types of surfaces with different inclination angles in a direction perpendicular to the main surface, and the inclination angle of the surface located closer to the main surface is greater than the inclination angle of the surface located further away from the main surface.

7. The resin honeycomb molded article according to claim 6, wherein the ratio of the length of the surface located on the side farther from the main surface to the total length of the partition wall is 5% or more and 85% or less.

8. The resin honeycomb molded article according to claim 6, 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 is 5% or more and 85% or less.

9. The resin honeycomb molded body according to claim 1 or 2, wherein the shape of the cylindrical cell is a hexagonal prism shape.

10. The resin honeycomb molded body according to claim 1 or 2, wherein the plate-like portion and the partition wall are integrally molded.

11. A resin honeycomb molded body according to claim 1 or 2, which is in the shape of a plate.

12. The resin honeycomb molded body according to claim 1 or 2, 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.

13. The resin honeycomb molded body according to claim 1 or 2, used as an under cover that covers at least a portion of the lower surface of a moving body.

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

15. 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, defining a plurality of cylindrical cells, the method comprising: injecting the resin material into a mold having a bottom surface portion having a main surface; and a plurality of independent protrusions extending from the main surface of the bottom surface portion in a direction intersecting the main surface, and regularly arranged at predetermined intervals, and curing the resin material; and removing the cured resin material from the mold, wherein the mold has a first surface and a second surface facing each other, and the inclination angle θ4, which is the angle the second surface makes with the normal direction of the main surface, is greater than the inclination angle θ3, which is the angle the first surface makes with the normal direction of the main surface.

16. The method for manufacturing a resin honeycomb molded article according to claim 15, wherein in the mold, the second surface of the pin is the surface opposite to the surface facing the shrinkage center of the resin material.

17. The method for manufacturing a resin honeycomb molded article according to claim 15 or 16, wherein the inclination angle θ3 is θ3 > 0°.

18. The method for manufacturing a resin honeycomb molded article according to claim 15 or 16, wherein the mold comprises a first protrusion and a second protrusion located further from the shrinkage 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.

19. The method for manufacturing a resin honeycomb molded article according to claim 15 or 16, wherein the inclination angle θ3 is 2° ≥ θ3 ≥ 0°.

20. The method for manufacturing a resin honeycomb molded article according to claim 15 or 16, wherein the shape of the cylindrical cell is a hexagonal prism shape.

21. The method for manufacturing a resin honeycomb molded article according to claim 15 or 16, wherein the plate-like portion and the partition wall are integrally molded.

22. A mold used for manufacturing a resin honeycomb molded body, comprising a resin material, 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 mold comprises a bottom surface having a main surface, and a plurality of independent protrusions extending from the main surface of the bottom surface in a direction intersecting the main surface, and regularly arranged at predetermined intervals, wherein the protrusions have a first surface and a second surface facing each other, and the inclination angle θ4, which is the angle the second surface makes with the normal direction of the main surface, is greater than the inclination angle θ3, which is the angle the first surface makes with the normal direction of the main surface (θ4 > θ3 ≥ 0°).

23. The mold according to claim 22, wherein the second surface of the protrusion is the surface opposite to the surface facing the shrinkage center of the resin material.

24. The mold according to claim 22 or 23, wherein the inclination angle θ3 is θ3 > 0°.

25. The mold according to claim 22 or 23, wherein the protrusion comprises a first protrusion and a second protrusion located further from the shrinkage 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.

26. The mold according to claim 22 or 23, wherein the inclination angle θ3 is 2° ≥ θ3 ≥ 0°.

27. The mold according to claim 22 or 23, wherein at least one of the first surface and the second surface of the protruding portion has two types of surfaces with different inclination angles in a direction perpendicular to the main surface, and the inclination angle of the surface located on the side farther from the main surface is greater than the inclination angle of the surface located on the side closer to the main surface.

28. The mold according to claim 27, wherein the ratio of the length of the surface located closer to the main surface to the total length of the partition wall is 5% or more and 85% or less.

29. The mold according to claim 27, wherein, on the surface located closer to the main surface, the ratio of the thickness of the partition wall to the length of the surface closer to the main surface is 5% or more and 85% or less.

30. The mold according to claim 22 or 23, wherein the protruding portion forms a regular hexagon in plan view.

Images