Method for manufacturing damping structure

Abstract

To provide a method for manufacturing a vibration control structure capable of improving a vibration reduction effect without excessively increasing manufacturing cost and mass of a vibration control material.SOLUTION: The method for manufacturing the damping structure includes a first step of disposing the first resin on the surface of the panel member 1, a second step of curing the surface of the first resin by heating, a third step of disposing the second resin to be the constraining layer 3 on the surface of the first resin, and a fourth step of forming the constraining layer 3 by curing the second resin by heating the first resin and the second resin, and forming the damping material 2 by foaming the inside of the first resin.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a vibration-damping structure for a panel member such as a floor panel of a vehicle. [Background technology]

[0002] Various structures have been proposed to reduce vibrations in floor panels that constitute the floor of a vehicle while the vehicle is running. For example, as described in Patent Document 1, a structure is known in which a vibration-damping material with damping properties, such as asphalt-based resin, is applied to low-rigidity areas of the floor panel that are prone to vibration.

[0003] In such a structure where vibration-damping material is applied to the floor panel, the vibration energy transmitted from the vehicle frame to the floor panel while the vehicle is moving is converted into heat energy by the vibration-damping material, thereby reducing the vibration of the floor panel. As a result, ride comfort and NVH performance (i.e., the ability to reduce noise, vibration, and harshness) are improved. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-315627 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above structure, the amount of vibration-damping material must be increased in order to further improve the vibration-reducing effect, so there is room for improvement in terms of manufacturing costs and the vibration-damping effect relative to the mass of the vibration-damping material.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a method for manufacturing a vibration-damping structure that can improve the vibration reduction effect without excessively increasing the manufacturing cost or the mass of the vibration-damping material. [Means for solving the problem]

[0007] The present invention provides a method for manufacturing a vibration-damping structure comprising a panel member, a vibration-damping material made of a first resin that has the property of hardening the surface and foaming internally when heated, and fixed to at least one surface of the panel member, and a constraining layer made of a thermosetting second resin that is less likely to deform than the vibration-damping material, and fixed to the surface of the vibration-damping material opposite the panel member, the method comprising: a first step of disposing the first resin on at least one surface of the panel member; a second step of hardening the surface of the first resin by heating; a third step of disposing the second resin on the surface of the first resin; and a fourth step of heating the first resin and the second resin to harden the second resin and form the constraining layer and foam the interior of the first resin, to form the vibration-damping material.

[0008] According to this manufacturing method, the surface of the first resin, which will become the vibration-damping material, is pre-hardened by heating in the second step, and then the second resin, which will become the constraining layer, is disposed on the surface of the first resin to cover the surface of the first resin in the third step. Thereafter, the first resin and the second resin are heated in the fourth step to form the vibration-damping material and the constraining layer.

[0009] That is, after the surface of the first resin is covered with the second resin in the third step, the first resin is reheated in the fourth step, which promotes foaming inside the first resin, making it possible to increase the film thickness of the formed damping material. This makes it possible to improve the vibration reduction effect of the damping structure without excessively increasing the manufacturing cost or the mass of the damping material.

[0010] In the above-described method for manufacturing a vibration-damping structure, it is preferable that the first resin is disposed in two or more layers in the first step, and the second resin is disposed on the surface of the uppermost layer of the first resin in the third step.

[0011] According to this feature, by covering the surface of the uppermost first resin layer with the second resin in the third step, the heating of the first resin in the subsequent fourth step promotes foaming inside all of the laminated first resin layers, thereby making it possible to increase the film thickness of the formed vibration-damping material, thereby achieving the film thickness increasing effect.

[0012] In the above-mentioned method for manufacturing a vibration-damping structure, it is preferable that in the first step, the first resin is applied in a strip shape so as to form a plurality of convex rib portions on the surface of the first resin, in the second step, the plurality of convex rib portions are hardened by heating, and in the third step, the second resin is applied so as to penetrate into the concave rib portions formed between adjacent convex rib portions.

[0013] According to this feature, in the first and second steps, a plurality of ridges are formed on the surface of a first resin that will become the damping material and then cured. Then, in the third step, a second resin is applied so as to impregnate the spaces between the ridges. In the fourth step, the second resin is heated and cured to form a constraining layer that constrains the ridges of the damping material to each other. This increases the constraining effect of the constraining layer on the damping material, further improving the vibration damping effect.

[0014] In the above-mentioned method for manufacturing a vibration-damping structure, the panel member is a floor panel that is fixed to a frame extending in the fore-and-aft direction of the vehicle body and forms the floor of the vehicle, and in the first step, it is preferable that the first resin is applied to the floor panel in a transverse direction that intersects with the fore-and-aft direction of the vehicle, thereby forming the multiple convex rib portions extending in the transverse direction.

[0015] The floor panel is fixed to a frame that extends in the vehicle's longitudinal direction. Therefore, the floor panel's bending rigidity in the longitudinal direction is strong due to the reinforcing effect of the frame. However, the bending rigidity in directions intersecting the longitudinal direction, particularly the vehicle width direction, is weaker due to the weak reinforcing effect of the frame. Therefore, the floor panel is most susceptible to bending deformation in the vehicle width direction when subjected to external vibrations.

[0016] Therefore, in the above manufacturing method, the first resin is applied to the floor panel in a direction intersecting the vehicle longitudinal direction, thereby forming the above-mentioned multiple ridges extending in the intersecting direction. The constraining layer formed in the fourth step constrains the spaces between the consecutive ridges in the intersecting direction. This increases the rigidity of the vibration-damping material, allowing strain energy to be accumulated in the vibration-damping material. As a result, it is possible to improve the vibration-damping effect.

[0017] In the above-mentioned method for manufacturing a vibration damping structure, it is preferable that in the first step, the first resin is applied in a vehicle width direction perpendicular to the vehicle fore-and-aft direction to form the multiple convex streak portions extending in the vehicle width direction.

[0018] This manufacturing method applies the first resin in the vehicle width direction, which is the direction in which the bending rigidity of the floor panel is weakest, thereby forming a damping material with multiple ridges extending in the vehicle width direction. This allows more strain energy to be accumulated in the damping material, resulting in improved vibration damping.

[0019] In the above-mentioned method for manufacturing a vibration-damping structure, it is preferable that the panel member is a floor panel that constitutes the floor of a vehicle and has a curved portion that is curved downward or upward from the floor panel, and that in the first step, the first resin is applied to the curved portion.

[0020] When a floor panel has a curved portion that curves downward or upward, the curved portion has weaker bending rigidity than other flat portions of the floor panel. Therefore, a vibration-damping material is formed by applying a first resin to the curved portion of the floor panel that has weak bending rigidity. This allows strain energy to be stored in the vibration-damping material, whose rigidity is increased by the constraining layer between the convex ridges as described above. As a result, it is possible to improve the vibration-damping effect.

[0021] In the above-mentioned method for manufacturing a vibration-damping structure, in the first step, it is preferable that the first resin is applied to the curved shaped portion in multiple applications spaced apart from each other around the center so that the first resin extends radially in the centrifugal direction from the center of the curved shaped portion when viewed from one side in the vertical direction, thereby forming the multiple convex ridge portions extending in the centrifugal direction.

[0022] Since the bending rigidity in the direction from the center to the periphery of the curved portion is particularly weak, forming multiple ridges extending in the centrifugal direction as described above allows more strain energy to be accumulated in the vibration-damping material, thereby further improving the vibration-damping effect.

[0023] In the above-described method for manufacturing a vibration damping structure, the curved portion is preferably a spare tire pan for accommodating a spare tire.

[0024] The spare tire pan is a curved portion with a relatively large diameter that can accommodate a spare tire. The bending rigidity of such a spare tire pan is particularly weak compared to the bending rigidity of other parts of the floor panel. Therefore, by disposing a vibration-damping material in the spare tire pan, strain energy can be stored in the vibration-damping material. As a result, it is possible to improve the vibration-damping effect of the spare tire pan.

[0025] In the above-mentioned method for manufacturing a vibration-damping structure, it is preferable that the floor panel is fixed to a plurality of cross members in the vehicle body that are spaced apart in the fore-and-aft direction of the vehicle and extend in the width direction of the vehicle, and that the curved portion is a part of the area of ​​the floor panel between the plurality of cross members.

[0026] The bending stiffness of the curved floor panel between the cross members is particularly weak. By forming the vibration-damping material in this area, more strain energy can be stored in the vibration-damping material. As a result, it is possible to improve the vibration damping effect in the area between the cross members of the floor panel.

[0027] In the above-mentioned method for manufacturing a vibration-damping structure, it is preferable that in the first step, the first resin is applied in the vehicle width direction in the area between the cross members to form the multiple convex streak portions extending in the vehicle width direction.

[0028] In this manufacturing method, the first resin is applied in the vehicle width direction to the area between the cross members, so that the vibration-damping material extends in the vehicle width direction and is fixed to the area, and the multiple ridges of the vibration-damping material are continuous in the vehicle width direction. This allows for even greater accumulation of strain energy in the vibration-damping material. As a result, it is possible to further improve the vibration-damping effect in the area between the cross members.

[0029] In the above-described method for manufacturing a vibration-damping structure, the second resin is preferably made of a clear coating material.

[0030] By using a clear coating material as the second resin, it is possible to manufacture the above-mentioned vibration damping structure using conventional vehicle manufacturing equipment that performs clear coating.

[0031] In the above-described method for manufacturing a vibration damping structure, it is preferable that in the fourth step, the first resin is heated at a temperature higher than the heating temperature in the second step.

[0032] According to this feature, by making the reheating temperature of the first resin in the fourth step higher than the heating temperature in the second step, it is possible to reliably foam the inside of the first resin and reliably increase the film thickness of the vibration-damping material. [Effects of the Invention]

[0033] As described above, according to the method for manufacturing a vibration-damping structure of the present invention, it is possible to improve the vibration-damping effect without excessively increasing the manufacturing cost or the mass of the vibration-damping material. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is a partially cutaway perspective view showing the overall configuration of a vibration-damping structure manufactured by a method for manufacturing a vibration-damping structure according to an embodiment of the present invention. [Figure 2] 3 is a flowchart showing the steps of a method for manufacturing a vibration damping structure according to an embodiment of the present invention. [Figure 3] The figures show examples of damping structures for investigating the effect of increasing film thickness by the manufacturing method of this embodiment, with I to III showing structures having 1 to 3 layers of damping material as this embodiment and a constraining layer fixed to the uppermost damping material, and IV to VI showing structures having only 1 to 3 layers of damping material and no constraining layer as comparative examples. [Figure 4] 4 is a graph showing the relationship between the number of layers of the damping material and the total film thickness of the damping material and the constraining layer for each of the structures I to VI in FIG. [Figure 5] 1A and 1B are diagrams showing the process by which strain energy accumulates at the corners of the convex rib portion and the corners of the concave rib portion of the vibration-damping material of this embodiment in response to vibration input, where (a) is a diagram of the state before vibration, and (b) is a diagram of the state in which strain energy accumulates at the corners during vibration. [Figure 6] 1 is a perspective view showing a structure in which the vibration damping structure of the present embodiment is applied to a floor panel of a vehicle. [Figure 7] 1 is an enlarged perspective view showing a structure in which the vibration damping structure of this embodiment is applied to a spare tire pan, which is a curved portion of a floor panel of a vehicle, and in which a plurality of vibration damping materials extend radially. [Figure 8] 1 is an enlarged perspective view showing a structure in which the vibration damping structure of the present embodiment is applied to a spare tire pan having an opening that is a curved portion of a floor panel of a vehicle. FIG. [Figure 9] 9 is an enlarged plan view showing a plurality of vibration-damping materials extending radially from a ridge line formed around the opening in FIG. 8. FIG. [Figure 10] 2A and 2B are diagrams for explaining shear deformation of the damping material due to bending deformation of the panel member caused by the vibration of FIG. 1, where (a) is a comparative example showing that no shear deformation occurs when there is no constraining layer, and (b) is a diagram showing the present embodiment showing that shear deformation occurs due to the constraint of the damping material by the constraining layer. [Figure 11] 2A and 2B are diagrams showing the distribution of strain energy accumulated in the damping material due to bending deformation of the panel member of FIG. 1, where (a) is a diagram showing, as a comparative example, that the accumulated strain energy is small when there is no constraining layer, and (b) is a diagram showing, as this embodiment, that the accumulated strain energy is large due to the constraint of the damping material by the constraining layer. [Figure 12] FIG. 1 is a diagram schematically illustrating a test specimen in which a vibration-damping material corresponding to this embodiment is applied vertically to a panel member. [Figure 13] 13 is a graph showing the relationship between the frequency of the input vibration wave and the inertance when the vibration control structure in which the structures I to VI of FIG. 3 are applied to the test specimen of FIG. 12 as this embodiment and the structure X consisting only of a panel member are vibrated. [Figure 14] FIG. 10 is a diagram schematically illustrating a structure in which a vibration-damping material is horizontally applied to a panel member as a comparative example. [Figure 15] 15 is a graph showing the relationship between the frequency of the input vibration wave and the inertance when a vibration control structure in which structures I to VI of FIG. 3 are applied to the test specimen of FIG. 14 as a comparative example, and a structure X consisting only of a panel member are vibrated. [Figure 16] 2 is an explanatory diagram schematically showing the application direction and two bending directions of the vibration-damping material of the present embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0035] Hereinafter, a method for manufacturing a vibration damping structure according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0036] (Basic configuration of vibration control structure) First, a vibration-damping structure manufactured by the manufacturing method of this embodiment will be described. The vibration-damping structure shown in Fig. 1 includes a plate-shaped panel member 1, a vibration-damping material 2 fixed by coating or the like to at least one surface of the panel member 1, in this embodiment, the upper surface 1a, and a constraining layer 3 fixed to the surface of the vibration-damping material 2 opposite the panel member 1, in this embodiment, the upper surface 2c. In this vibration-damping structure, the panel member 1, the vibration-damping material 2, and the constraining layer 3 are stacked in this order and bonded to each other to form a three-layer laminated structure. Note that the vibration-damping material 2 and the constraining layer 3 may be fixed to the lower surface 1c of the panel member 1, or may be fixed to both the upper surface 1a and the lower surface 1c of the panel member 1.

[0037] The panel member 1 is a plate-like member attached to a location that receives external vibrations, and is used, for example, as a floor panel 21 (see FIGS. 6 to 8) that constitutes the floor of a vehicle, which will be described later. The panel member 1 is used with at least both opposing end portions 1b, and preferably the end portions around the entire periphery of the panel member 1, fixed. The present invention does not particularly limit the material of the panel member 1, but when used as a floor panel 21 of an automobile, a thin steel plate or the like is used.

[0038] The damping material 2 is fixed to the upper surface 1a of the panel member 1 by coating or pasting. The damping material 2 is a material capable of damping vibrations transmitted to the panel member 1, and is made of a first resin that hardens on the surface and foams internally when heated, as described below. The first resin may be, for example, an acrylic emulsion paint, or more specifically, a material containing a foaming agent that foams on heating, such as an acrylic emulsion paint, a polyurethane resin paint, an epoxy resin paint, or a vinyl chloride plastisol paint. The damping material 2 may have sufficient rigidity or elasticity to exhibit vibration damping performance; for example, a Young's modulus of approximately 400 to 700 MPa is sufficient, and the acrylic emulsion paint has a Young's modulus of approximately 600 MPa.

[0039] As shown in Figure 1, the damping material 2 used in this embodiment is made of a first resin that is an acrylic emulsion paint applied in a predetermined first direction D1 and that foams and hardens on the surface and foams internally when heated. Therefore, the damping material 2 has a layer containing air bubbles formed on the upper surface 1a of the panel member 1. Because the damping material 2 contains air bubbles, it is able to damp the vibration of the panel member 1 by storing the vibration energy transmitted to the panel member 1 as strain energy.

[0040] The vibration-damping material 2 also has a plurality of ridges 11 and a plurality of grooves 12 on its upper surface 1a.

[0041] The plurality of ridge portions 11 are continuous (i.e., extend) along a first direction D1, which is a direction in which the vibration-damping material 2 is pulled or compressed, when a bending load B is applied to the panel member 1, specifically, when a bending load B caused by external vibration is applied to the panel member 1 to which both opposing end portions 1b are fixed. The plurality of ridge portions 11 are also arranged at intervals from one another in a second direction D2 that is perpendicular to the first direction D1.

[0042] Each of the plurality of recessed streaks 12 is formed between two adjacent protruding streaks 11.

[0043] The multiple convex ribs 11 are formed by applying a first resin, such as an acrylic emulsion paint, that will become the vibration-damping material 2 from multiple nozzles onto the upper surface 1a of the panel member 1 so that the resin extends in the first direction D1, and then heating the paint to cause internal foaming and surface hardening. Therefore, each convex rib 11 is a continuous body extending in the first direction D1 and having a substantially semicircular or substantially rectangular cross section. Meanwhile, the concave rib 12 formed between two adjacent convex ribs 11 is a groove extending in the first direction D1 and having a shape that corresponds to the opposing surfaces of the two adjacent convex ribs 11.

[0044] The constraining layer 3 is fixed by coating or the like to the surface of the damping material 2 opposite to the panel member 1, that is, to the upper surface 2c in this embodiment.

[0045] The constraining layer 3 is made of a thermosetting second resin that is less likely to deform than the damping material 2, such as an acrylic resin that is used for clear coating the surface of a vehicle during vehicle manufacture. The constraining layer 3 only needs to have properties (e.g., high rigidity and high elasticity) that make it less likely to deform than the damping material 2; for example, a Young's modulus of approximately 1300 to 2000 MPa is sufficient, and the above-mentioned acrylic resins have a high Young's modulus of approximately 1650 MPa. Therefore, the constraining layer 3 has higher elasticity than the damping material 2, and is therefore less likely to undergo bending deformation or tensile / compressive deformation.

[0046] The constraining layer 3 needs to be impregnated into at least the groove portion 12. This makes it possible to constrain the protrusions 11 on both sides of the groove portion 12 by the constraining layer 3 impregnated into the groove portion 12.

[0047] In this embodiment, as shown in FIG. 1, the constraining layer 3 entirely covers the plurality of ridges 11 and grooves 12 of the vibration-damping material 2 .

[0048] (Explanation of the manufacturing method of the vibration damping structure) By using the manufacturing method according to the embodiment of the present invention, the vibration damping structure shown in FIG. 1 is manufactured in accordance with the procedure of the flowchart shown in FIG.

[0049] First, in a preparation step S1, a floor panel 21 (see FIGS. 6 to 8) that constitutes the floor of a vehicle is prepared as a panel member 1 of a vibration damping structure.

[0050] Next, in the first step S2, a first resin such as an acrylic emulsion paint that will become the vibration-damping material 2 is applied to the upper surface of the floor panel 21 by coating or pasting.

[0051] Then, in the second step S3, the surface of the first resin is hardened by heating. At this time, some foaming (pre-foaming) may be performed along with the surface hardening of the first resin. Heating in the second step S3 and the fourth step S5 described below is performed using an existing paint drying oven or the like used in automobile manufacturing.

[0052] Then, in the third step S4, a second resin such as an acrylic resin that will become the constraining layer 3 is disposed on the first resin by coating or the like. The second resin such as an acrylic resin is applied to a film thickness of about 20 to 30 μm for clear coating, for example.

[0053] Then, in a fourth step S5, the first resin and the second resin are heated to harden the second resin to form the constraining layer 3, and foam the inside of the first resin to form the vibration-damping material 2.

[0054] According to this manufacturing method, the surface of the first resin that will become the vibration-damping material 2 is pre-hardened by heating in the second step S3, and then the second resin that will become the constraining layer 3 is disposed on the first resin in the third step S4 to cover the first resin. Then, in the fourth step S5, the first resin and the second resin are heated to form the vibration-damping material 2 and the constraining layer 3.

[0055] That is, after the surface of the first resin is covered with the second resin in the third step S4, the first resin is reheated in the fourth step S5, which promotes foaming inside the first resin, thereby making it possible to increase the film thickness of the formed damping material 2. This makes it possible to improve the vibration reduction effect of the damping structure without excessively increasing the manufacturing cost or the mass of the damping material.

[0056] In the above manufacturing method, the second resin that becomes the constraining layer 3 is preferably made of a clear coating material. In this case, it is possible to realize the above vibration damping structure using conventional vehicle manufacturing equipment that performs clear coating.

[0057] In the above manufacturing method, it is preferable to heat the first resin in the fourth step S5 at a temperature higher than the heating temperature in the second step S3, which ensures that the inside of the first resin is foamed and the film thickness of the vibration-damping material 2 is increased.

[0058] For example, in the second step S3, the first resin is heated for the first time at a heating temperature of about 110-120°C for about 10-60 minutes to harden the surface of the first resin, and then in the third step S4, the second resin that will become the constraining layer 3 is applied to seal the top of the first resin, and then in the fourth step S5, the first resin is heated for the second time at a heating temperature of about 130-160°C for about 15-60 minutes to foam the inside of the first resin. This makes it possible to form a vibration-damping material 2 with a sufficient thickness.

[0059] (Verification of the effect of increasing film thickness) Next, the effect of increasing the thickness of the damping material 2 by the above manufacturing method will be verified with reference to FIGS.

[0060] Figure 3 shows examples of damping structures for investigating the effect of increasing film thickness by the manufacturing method of the embodiment, where I to III show structures having 1 to 3 layers of damping material 2 as this embodiment and a constraining layer 3 fixed to the topmost damping material 2, and IV to VI show structures having only 1 to 3 layers of damping material 2 and no constraining layer as comparative examples.

[0061] FIG. 4 is a graph showing the relationship between the number of layers N of the damping material 2 and the total thickness A of the damping material 2 and the constraining layer 3 for each of the structures I to VI in FIG.

[0062] As is clear from the graph in Figure 4, in the structures I to III in this embodiment in which the constraining layer 3 is fixed to the top layer of the damping material 2, the film thickness A of the entire damping material 2 and the constraining layer 3 is improved when compared with the structures IV to VI in the comparative examples in which the number of layers N of the damping material 2 is the same.

[0063] It is clear that the improvement in the overall film thickness A in these structures I to III is due to the fact that, as described above, in the third step S4, the surface of the first resin that becomes the vibration-damping material 2 is covered with the second resin that becomes the constraining layer 3, and then the first resin is reheated in the fourth step S5, thereby promoting foaming inside the first resin.

[0064] Furthermore, in the graph of FIG. 4, when we look at the increase in the overall film thickness A in the structures I to III relative to the structures IV to VI, we can see that the increase in the film thickness A increases as the number of layers N of the vibration-damping material 2 increases.

[0065] From the results of the graph in Figure 4, it can be seen that in the manufacturing method shown in Figure 2 above, it is preferable that in the first step, the first resin is stacked and arranged in two or more layers, and in the third step, the second resin is arranged on the surface of the topmost layer of the first resin.

[0066] In this way, by covering the surface of the uppermost first resin layer with the second resin in the third step, the heating of the first resin in the subsequent fourth step promotes foaming inside all of the laminated first resin layers, making it possible to increase the film thickness of the formed vibration-damping material, thereby achieving the film thickness increasing effect.

[0067] (Improvement of vibration damping effect by forming the ridges 11) Furthermore, when manufacturing the above-described vibration-damping structure, it is possible to improve the vibration-damping effect by forming a ridge portion 11 on the vibration-damping material 2, as shown in Fig. 1. The manufacturing method for forming the ridge portion 11 is as follows.

[0068] 2, the manufacturing method begins by applying a first resin to the panel member 1 in a strip shape so as to form a plurality of ridges 11 on the surface of the first resin that will become the damping material 2. Specifically, the first resin, such as an acrylic emulsion paint, that will become the damping material 2 is applied from a plurality of nozzles to the upper surface 1a of the panel member 1 so as to extend in a predetermined first direction D1, thereby forming the plurality of ridges 11.

[0069] Next, in the second step S3, the plurality of ridges 11 are hardened by heating.

[0070] Next, in the third step S4, the second resin that will become the constraining layer 3 is applied so as to impregnate the recessed streak portions 12 formed between the adjacent protruding streak portions 11.

[0071] Thereafter, in a fourth step S5, the second resin is heated and cured to form a constraining layer 3, which constrains the ridge portion 11.

[0072] In this way, by constraining the convex rib portions 11 of the vibration-damping material 2 with each other by the constraining layer 3, the constraining effect of the constraining layer 3 on the vibration-damping material 2 is increased, and the vibration damping effect is further improved.

[0073] Furthermore, in the vibration-damping structure shown in FIG. 1 above, the multiple convex rib portions 11 of the vibration-damping material 2 are continuous in a first direction D1, which is the direction in which the vibration-damping material 2 is tensilely deformed when a bending load B is input. Therefore, when the schematic cross-sectional views of the vibration-damping material 2 and the constraining layer 3 are viewed as in FIGS. 5(a) and 5(b), strain energy is not accumulated in the vibration-damping material 2 in the pre-vibration state of FIG. 5(a), but strain energy accumulates in the vibration-damping material 2 in the vibrating state of FIG. 5(b), with the largest amount of strain energy E accumulated in the corners 11a of the convex rib portions 11 and the corners 12a of the concave rib portions 12 of the vibration-damping material 2. Therefore, it can be seen that a vibration-damping structure in which the multiple convex rib portions 11 are constrained by the constraining layer 3 as shown in FIG. 1 has a high vibration-damping effect.

[0074] In the manufacturing method of the vibration-damping structure of this embodiment, it is preferable that the constraining layer 3 entirely covers the multiple ridge portions 11 and groove portions 12 of the vibration-damping material 2. This allows the multiple ridge portions 11 to be tightly and integrally constrained by the constraining layer 3, further improving the bending rigidity of the vibration-damping material 2. Therefore, the amount of strain energy stored in the vibration-damping material 2 is further improved, and the vibration-reducing effect can be further improved.

[0075] (Application example of the manufacturing method of this embodiment) The manufacturing method for manufacturing a vibration-damping structure in which multiple convex streak portions 11 are formed on the vibration-damping material 2 as shown in Figure 1 above can be applied to manufacturing a vibration-damping structure suitable for damping vibrations in vehicle floor panels.

[0076] That is, in the manufacturing method of the above-mentioned vibration-damping structure, before the first step S2 of Figure 2, as a preparation step S1, a floor panel 21 constituting the floor of the vehicle shown in Figure 6 is prepared as the panel member 1 of Figure 1, and is fixed to a center frame 22 and side frames 23 extending in the fore-and-aft direction of the vehicle body.

[0077] The center frame 22 is a frame such as a floor tunnel that extends in the vehicle longitudinal direction X at a central position in the vehicle width direction Y under the vehicle body 20. The side frames 23 are frames such as side sills that extend in the vehicle longitudinal direction X at both ends in the vehicle width direction Y. Note that it is sufficient that the floor panel 21 is fixed to at least one frame that extends in the longitudinal direction. Furthermore, portions of the floor panel 21 other than the ends may be fixed to the frame.

[0078] In the first step S2, the first resin is applied to the floor panel 21 in a transverse direction intersecting the vehicle longitudinal direction X, for example, in the vehicle width direction Y, as shown in Fig. 6, to form the above-mentioned plurality of convex stripes 11 extending in the transverse direction. The subsequent second step S3 to fourth step S5 are the same as those described above.

[0079] Both ends of the floor panel 21 are fixed to frames 22, 23 extending in the vehicle longitudinal direction X. Therefore, the bending rigidity of the floor panel 21 in the vehicle longitudinal direction X is increased by the reinforcing effect of the frames 22, 23.

[0080] On the other hand, the bending rigidity in the transverse direction intersecting the vehicle longitudinal direction X, particularly in the vehicle width direction Y, is weak because the reinforcing effect of frames 22, 23 is low. Therefore, floor panel 21 is most susceptible to bending deformation in the vehicle width direction Y when subjected to external vibrations.

[0081] Therefore, in the above manufacturing method, the first resin is applied to the floor panel 21 in a transverse direction intersecting the vehicle longitudinal direction X, for example, in the vehicle width direction Y, as shown in FIG. 6, to form the above-mentioned multiple convex streaks 11 extending in the transverse direction. The constraining layer 3 formed in the fourth step S5 constrains the spaces between the convex streaks 11 that are continuous in the transverse direction. This increases the rigidity of the vibration-damping material 2, allowing strain energy to be accumulated in the vibration-damping material 2. As a result, it is possible to improve the vibration-damping effect.

[0082] In addition, in the manufacturing method of the vibration damping structure of this embodiment, in the first step S2, the first resin is applied in the vehicle width direction Y, which is perpendicular to the vehicle fore-and-aft direction X, to form multiple convex streak portions 11 extending in the vehicle width direction Y.

[0083] In this manufacturing method, the damping material 2 extends in the vehicle width direction Y, which is the direction in which the bending rigidity of the floor panel 21 is weakest, and the multiple protruding ridges 11 are continuous in the vehicle width direction Y, so more strain energy can be accumulated in the damping material 2. As a result, it is possible to further improve the vibration damping effect.

[0084] The floor panel 21 is fixed to a plurality of cross members 24 that are spaced apart from each other in the vehicle longitudinal direction X and extend in the vehicle width direction Y in the vehicle body.

[0085] The floor panel 21 has a region 25 between the multiple cross members 24 in the floor panel 21 as a curved portion that curves downward or upward.

[0086] In this case, the bending rigidity of the curved portion of floor panel 21 in region 25 between multiple cross members 24 is particularly weak, so by forming vibration-damping material 2 in this region 25, more strain energy can be accumulated in vibration-damping material 2. As a result, it is possible to improve the vibration damping effect in region 25 between cross members 24 of floor panel 21.

[0087] In the first step S2, it is preferable to form a plurality of convex strip portions 11 extending in the vehicle width direction Y by applying the first resin that will become the vibration-damping material 2 in the region 25 between the cross members 24 in the vehicle width direction Y.

[0088] In the vibration-damping structure of this embodiment, as shown in FIG. 6 , the vibration-damping material 2 extends in the vehicle width direction Y in the region 25 between the cross members 24. The multiple convex streak portions 11 are provided with the vehicle width direction Y as the first direction D1. With this configuration, the bending rigidity in the vehicle width direction Y in the region 25 between the cross members 24 is particularly weak, so the first resin can be applied to the region 25 in the vehicle width direction Y to form a vibration-damping material 2 having multiple convex streak portions 11 extending in the vehicle width direction Y. This allows strain energy to be further accumulated in the vibration-damping material 2. As a result, it is possible to further improve the vibration damping effect in the region 25 between the cross members 24.

[0089] In the manufacturing method of the vibration-damping structure of this embodiment, it is preferable to arrange the vibration-damping material 2 in region R below the seats on the floor panel 21, as shown in Fig. 6. Seats such as the driver's seat, passenger seat, and rear seats are arranged in region R. According to this manufacturing method, vibrations occurring in region R below the seats on the floor panel 21 are easily sensed by occupants, so by arranging the vibration-damping material 2 in this region 25, vibrations of the floor panel 21 are less likely to be sensed by occupants, improving comfort.

[0090] (Explanation of application to spare tire pans 26 and 28 in Figures 7 and 8) Furthermore, in the preparation step S1 prior to the first step S2, as shown in Figures 7 and 8, a floor panel 21 that constitutes the floor of the vehicle may be prepared as the panel member 1, and the floor panel 21 may have, for example, spare tire pans 26, 28 as other curved portions that are curved downward or upward from the floor panel 21, and in the first step S2, a first resin that will become the vibration-damping material 2 may be applied to the curved portions, the spare tire pans 26, 28.

[0091] As shown in FIGS. 7 and 8 , when the floor panel 21 has curved portions such as spare tire pans 26 and 28, the curved portions have weaker bending rigidity than the other flat portions of the floor panel 21. In particular, the bending rigidity is extremely weak compared to the flat portions reinforced by the frames 22 and 23. Therefore, as described above, the first resin is applied to the spare tire pans 26 and 28, which are curved portions of the floor panel 21 with weak bending rigidity, to form the damping material 2. This allows strain energy to be stored in the damping material 2, whose rigidity has been increased by the constraining layer 3 between the ridge portions 11 as described above. As a result, it is possible to improve the vibration damping effect.

[0092] Furthermore, in the first step S2, as shown in Figures 7 and 8, it is preferable to form a plurality of convex rib portions 11 extending in the centrifugal direction by applying a first resin that will become the vibration-damping material 2 to the curved-shaped spare tire pans 26, 28 in multiple applications spaced apart from each other around the center of the curved-shaped spare tire pans 26, 28 so that the first resin extends radially in the centrifugal direction from the center when viewed from one side in the vertical direction, for example, from the top.

[0093] According to this manufacturing method, the bending rigidity of the spare tire pans 26, 28 in the direction from the center toward the periphery is particularly weak, so by forming the multiple ridges 11 extending in the centrifugal direction as described above, more strain energy can be accumulated in the vibration-damping material 2. As a result, it is possible to further improve the vibration damping effect.

[0094] 7 and 8, the curved portions are spare tire pans 26, 28 that accommodate a spare tire. The spare tire pans 26, 28 are curved portions with a relatively large diameter that can accommodate a spare tire. The bending rigidity of the spare tire pans 26, 28 is particularly weak compared to the bending rigidity of other portions of the floor panel 21. Therefore, by forming the vibration-damping material 2 in the spare tire pans 26, 28, strain energy can be accumulated in the vibration-damping material 2. As a result, the vibration damping effect of the spare tire pans 26, 28 can be improved.

[0095] In addition, when the spare tire pan 28 has an opening 27 in the center, as in the case of the spare tire pan 28 shown in Figure 8, multiple vibration-damping materials 2 can be made to extend radially from a ridge 29 formed around the opening 27, as shown in the enlarged view of Figure 9.

[0096] (Explanation of the vibration damping mechanism of vibration control structures) The vibration damping mechanism of the vibration damping structure of this embodiment will be described below.

[0097] First, the mechanism by which the constraining layer 3 in the vibration-damping structure of this embodiment increases the strain energy of the vibration-damping material 2 will be described.

[0098] As a comparative example, in the structure shown in Figure 10(a) in which only the damping material 2 is laminated on the panel member 1, when a bending load B is input to the panel member 1 and the damping material 2 is pulled in the first direction D1, the entire damping material 2 undergoes tensile deformation following the panel member 1, and it is therefore thought that the accumulation of strain energy in the damping material 2 is low. Looking at Figure 11(a), which shows the distribution of strain energy accumulated in the damping material 2 of Figure 10(a), it can be seen that the amount of strain energy accumulated in the damping material 2 is small, as there are few areas with dark colors indicating areas with large strain energy.

[0099] On the other hand, as shown in Figure 10(b), in a structure in which the damping material 2 and the constraining layer 3 are laminated on the panel member 1, which is a schematic illustration of this embodiment, the constraining layer 3 constrains the damping material 2 so that it does not undergo tensile deformation in the first direction D1, thereby making it possible to generate shear deformation, i.e., large shear deformation, at both ends of the damping material 2. This makes it possible to accumulate large strain energy in the damping material 2. Looking at Figure 11(b), which shows the distribution of strain energy accumulated in the damping material 2 of Figure 10(b), we can see that there are many areas with darker colors indicating areas with large strain energy compared to Figure 11(a), and the color is particularly dark in part P, indicating that a large amount of strain energy is accumulated in the damping material 2.

[0100] Next, the vibration damping effect of the vibration damping structure of this embodiment will be verified with reference to FIG. 3 and FIGS.

[0101] As examples of vibration-damping structures for investigating the vibration reduction effect, structures I to VI shown in Fig. 3 above are used. Here, I to III show structures having one to three layers of vibration-damping material 2 as this embodiment and a constraining layer 3 fixed to the uppermost layer of vibration-damping material 2, while IV to VI show structures having only one to three layers of vibration-damping material 2 and no constraining layer 3 as comparative examples.

[0102] Fig. 12 is a diagram schematically illustrating a test specimen in which the damping material 2 corresponding to this example is applied vertically to a panel member 1. That is, in the vertically applied test specimen shown in Fig. 12, the damping material 2 is applied in a first direction D1, which is a direction in which the panel member 1 is tensile or compressive when a bending load is applied thereto, and a plurality of convex ridge portions 11 are continuous in the first direction D1.

[0103] FIG. 13 is a graph showing the relationship between the frequency of the input vibration wave and the inertance (i.e., the ratio of the force and acceleration input to the object) when the vibration control structure in which the structures I to VI in FIG. 3 are applied to the test specimen in FIG. 12 as this embodiment and the structure X consisting of only the panel member 1 are vibrated.

[0104] Looking at the graph in Figure 13, when the damping material 2 is applied vertically to the panel member 1, both curves I to III, which show the inertance of the structure in which 1 to 3 layers of damping material 2 and constraining layer 3 are fixed in this embodiment, and curves IV to VI, which show the inertance of the structure in the comparative example having only 1 to 3 layers of damping material 2, have a greater effect in reducing the inertance peak than the inertance of structure X having only panel member 1, and the peaks are more gentle.

[0105] Furthermore, in the graph of Figure 13, the peaks of curves I to III, which show the inertance of the structure having the damping material 2 of this embodiment together with the constraining layer 3, are clearly lower than the peaks of curves IV to VI, which show the inertance of the structure of the comparative example having only the damping material 2 without the constraining layer 3, and it can be seen that the constraining layer 3 greatly contributes to improving the vibration damping effect.

[0106] On the other hand, as a comparative example, we also verify the vibration damping effect of a structure in which the damping material 2 is applied horizontally to a panel member 1, as shown in Fig. 14. In this horizontally applied test specimen shown in Fig. 14, the damping material 2 is applied in a second direction D2 that is perpendicular to a first direction D1, which is the direction in which the panel member 1 is tensile or compressed when a bending load is input, and multiple convex rib portions 11 are continuous in the second direction D2.

[0107] FIG. 15 is a graph showing the relationship between the frequency of the input vibration wave and the inertance when a vibration control structure in which structures I to VI in FIG. 3 are applied to the test body in FIG. 14 as a comparative example, and a structure X consisting of only a panel member 1 are vibrated.

[0108] 15, when the damping material 2 is applied horizontally to the panel member 1, both curves I to III, which show the inertance of the structure of this example in which one to three layers of damping material 2 and constraining layer 3 are fixed, and curves IV to VI, which show the inertance of the comparative example structure with only one to three layers of damping material 2, are less effective at reducing the inertance peaks than the graph of this example in which the damping material 2 is applied vertically, as shown in Fig. 13. Furthermore, in the graph of Fig. 15, the peaks of curves I to III, which show the inertance of the structure with constraining layer 3, are not nearly as low as the peaks of curves IV to VI, which show the inertance of the comparative example structure without constraining layer 3, indicating that the constraining layer 3 contributes little to vibration damping.

[0109] A comparison of the graphs in Figures 13 and 15 shows that the peaks of inertance for curves I to III in Figure 13 are significantly lower than the peaks for curves I to III in Figure 15, and therefore it can be seen that the test specimen in which the vibration-damping material 2 corresponding to this embodiment shown in Figure 12 is applied vertically to the panel member 1 has a higher vibration reduction effect than the test specimen in which the material is applied horizontally, which is the comparative example shown in Figure 14.

[0110] Here, with reference to Figure 16, we will further compare and consider the vibration damping effects of vertically applied damping material 2 and horizontally applied damping material 2. As shown in the schematic model in Figure 16, it can be seen that the damping material 2 applied vertically along the first direction D1 with respect to the bending direction B1 has high bending rigidity and a high vibration damping effect. On the other hand, when considering a structure in which the damping material 2 is applied horizontally with respect to the bending direction B2 (i.e., a structure in which the damping material 2 is applied in the first direction D1 that is perpendicular to the second direction D2 along the bending direction B2), it can be seen that the bending rigidity of the damping material 2 with respect to the bending direction B2 is low and the vibration damping effect is low. [Explanation of symbols]

[0111] 1 Panel member 2 Damping material 3 restraint layer 11 Convex portion 12 Concave section 21 Floor Panel 22 Center Frame 23 Side frame 24 Cross member 25 Area (Curved Shape) 26, 28 Spare tire pan (curved section) D1 1st direction D2 2nd direction

Claims

1. A panel member; a vibration-damping material made of a first resin having a property that the surface hardens and the interior foams when heated, and the vibration-damping material is fixed to at least one surface of the panel member; a constraining layer made of a thermosetting second resin, which has a property of being less likely to deform than the vibration-damping material, and which is fixed to a surface of the vibration-damping material opposite to the panel member, a first step of disposing the first resin on at least one surface of a panel member; a second step of curing the surface of the first resin by heating; a third step of disposing the second resin on a surface of the first resin; a fourth step of heating the first resin and the second resin to harden the second resin and form the constraining layer, and foaming the inside of the first resin to form the vibration-damping material; A method for manufacturing a vibration damping structure, comprising:

2. 2. The method for manufacturing a vibration damping structure according to claim 1, In the first step, the first resin is disposed in two or more layers, In the third step, the second resin is disposed on a surface of the first resin of the uppermost layer. A method for manufacturing a vibration damping structure comprising:

3. 2. The method for manufacturing a vibration damping structure according to claim 1, In the first step, the first resin is applied in a strip shape so as to form a plurality of ridge portions on a surface of the first resin; In the second step, the plurality of ridge portions are hardened by heating; In the third step, the second resin is applied so as to be impregnated into recessed portions formed between adjacent protruding portions. A method for manufacturing a vibration damping structure comprising:

4. 4. The method for manufacturing a vibration damping structure according to claim 3, The panel member is a floor panel that is fixed to a frame of a vehicle body extending in a vehicle front-rear direction and that constitutes a floor of the vehicle, In the first step, the first resin is applied to the floor panel in a transverse direction intersecting a vehicle longitudinal direction, thereby forming the plurality of protruding stripes extending in the transverse direction. A method for manufacturing a vibration damping structure comprising:

5. 5. The method for manufacturing a vibration damping structure according to claim 4, In the first step, the first resin is applied in a vehicle width direction perpendicular to a vehicle front-rear direction, thereby forming the plurality of protruding stripes extending in the vehicle width direction. A method for manufacturing a vibration damping structure comprising:

6. 4. The method for manufacturing a vibration damping structure according to claim 3, The panel member is a floor panel that constitutes a floor of a vehicle, and has a curved portion that is curved downward or upward of the floor panel, In the first step, the first resin is applied to the curved portion. A method for manufacturing a vibration damping structure comprising:

7. 7. The method for manufacturing a vibration damping structure according to claim 6, In the first step, the first resin is applied to the curved portion in a plurality of areas spaced apart from each other around the center of the curved portion so as to extend radially from the center of the curved portion in a centrifugal direction when viewed from one side in the vertical direction, thereby forming the plurality of protruding ridge portions extending in the centrifugal direction. A method for manufacturing a vibration damping structure comprising:

8. 7. The method for manufacturing a vibration damping structure according to claim 6, The curved portion is a spare tire pan that accommodates a spare tire. A method for manufacturing a vibration damping structure comprising:

9. 7. The method for manufacturing a vibration damping structure according to claim 6, The floor panel is fixed to a plurality of cross members in the vehicle body that are spaced apart from each other in the vehicle longitudinal direction and extend in the vehicle width direction, The curved portion is a portion of the floor panel in a region between the plurality of cross members. A method for manufacturing a vibration damping structure comprising:

10. 10. The method for manufacturing a vibration damping structure according to claim 9, In the first step, the first resin is applied in a vehicle width direction in an area between the cross members to form the plurality of protruding portions extending in the vehicle width direction. A method for manufacturing a vibration damping structure comprising:

11. The method for manufacturing a vibration damping structure according to any one of claims 1 to 10, The second resin is made of a clear coating material. A method for manufacturing a vibration damping structure comprising:

12. The method for manufacturing a vibration damping structure according to any one of claims 1 to 10, In the fourth step, the first resin is heated at a temperature higher than the heating temperature in the second step. A method for manufacturing a vibration damping structure comprising:

Images