JP2004169833A - Energy absorbing member and method for forming the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming an energy absorbing member of excellent productivity. <P>SOLUTION: An outer hollow body 14 and an energy absorbing body 13 are deformed by reducing a double hollow body having an inner hollow body 11 with through holes 12 formed in an outer circumference thereof, the outer hollow body 14 with the inner hollow body 11 inserted therein, the energy absorbing body 13 which is formed of porous metal, disposed between the inner hollow body 11 and the outer hollow body 14, and brought into contact with both the inner hollow body 11 and the outer hollow body 14, and thermosetting adhesive disposed between the outer hollow body 14 and the energy absorbing body 13. The adhesive is thermoset by the heat generated by the deformation of the outer hollow body 14, and fixes the outer hollow body 14 to the energy absorbing body 13. The porous metal constituting the energy absorbing body 13 is protruded in a fitting manner to the through hole 12 by the deformation of the energy absorbing body 13, and fixes the energy absorbing body 13 to the inner hollow body 11. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an energy absorbing member and a method for forming the same.
[0002]
[Prior art]
A conventional energy absorbing member includes a double cylindrical body having an outer cylindrical body and an inner cylindrical body. An energy absorbing body made of a porous metal is disposed between the outer cylindrical body and the inner cylindrical body. An adhesive is applied to fix the body and the inner cylindrical body to the energy absorber (for example, see Non-Patent Document 1).
[0003]
Further, there is a method in which a thermosetting adhesive is applied for fixing the metal liner and the composite coating (for example, see Patent Document 1).
[0004]
[Non-patent document 1]
Jay. Banhart, M. F. Ashby, N. A. Fleck (J. Banhart, M. F. Ashby, N.A. Fleck), Metal Foams and Porous Metal Structures, (Germany), M.I. , P. 313-316
[Patent Document 1]
JP-T-2000-504810 (FIG. 4)
[0005]
[Problems to be solved by the invention]
However, in the method described in Non-Patent Document 1, the adhesive is applied over the entire surface of the interface between the outer cylindrical body and the inner cylindrical body and the energy absorber, so that the material cost is increased and the production cost is increased. Have problems.
[0006]
In the method described in Patent Literature 2, it is necessary to add a heat treatment step for curing the adhesive, and there is a problem that the number of working steps and equipment costs increase, and the production cost increases.
[0007]
The present invention has been made in order to solve the problems associated with the above-described conventional technology, and has as its object to provide an energy absorbing member excellent in production cost and a method for forming the same.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 for achieving the above object,
An inner hollow body having a through hole formed in the outer periphery, an outer hollow body into which the inner hollow body is inserted, and disposed between the inner hollow body and the outer hollow body, wherein the inner hollow body and the outer hollow body are disposed. A double hollow body having an energy absorber made of a porous metal in contact with both the body and a thermosetting adhesive disposed between the outer hollow body and the energy absorber;
By contracting the tube, the outer hollow body and the energy absorber are deformed,
By the heat generated by the deformation of the outer hollow body, the adhesive is cured, and the outer hollow body and the energy absorber are fixed,
By deforming the energy absorber, the porous metal constituting the energy absorber is projected so as to fit with the through hole, and the energy absorber and the inner hollow body are fixed. This is a method for forming an energy absorbing member.
[0009]
According to an eleventh aspect of the present invention, there is provided an energy absorbing member formed by using the energy absorbing member forming method according to any one of the first to tenth aspects. Material.
[0010]
【The invention's effect】
The present invention configured as described above has the following effects.
[0011]
According to the first aspect of the present invention, since the adhesive is not used for fixing the energy absorber and the inner hollow body, the material cost can be reduced. The fixing of the outer hollow body and the energy absorber using the adhesive is performed simultaneously when the energy absorber and the inner hollow body are fixed. That is, an additional step for curing the adhesive is not required, and the number of work steps and equipment costs do not increase. Therefore, it is possible to provide a method for forming an energy absorbing member that is excellent in production cost.
[0012]
According to the eleventh aspect, it is possible to provide an energy absorbing member excellent in production cost.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an exploded view for explaining the configuration of the energy absorbing member according to the embodiment of the present invention.
[0014]
The energy absorbing member according to the embodiment of the present invention is formed by shrinking a double hollow body, and is used, for example, in an impact action portion of a vehicle body, and absorbs energy at the time of a collision to reduce an impact force. I do. The double hollow body has an inner hollow body 11, an energy absorber 13, an outer hollow body 14, and an adhesive (not shown).
[0015]
The inner hollow body 11 has a cylindrical shape, and a through hole 12 is formed on the outer periphery. The through hole 12 is used for fixing the inner hollow body 11 and the energy absorber 13.
[0016]
The energy absorber 13 is a cylindrical body made of a porous metal, is disposed between the inner hollow body 11 and the outer hollow body 14, and is in contact with both the inner hollow body 11 and the outer hollow body 14. The porous metal is, for example, aluminum foam, and the energy absorber 13 can be formed by hollowing out aluminum foam.
[0017]
The energy absorber 13 can be provided in at least a part of the inside of the space defined by the outer hollow body 14 and the inner hollow body 11. In addition, the material of the energy absorber 13 is not limited to aluminum foam, and it is also possible to apply another foam metal having excellent energy absorption.
[0018]
The outer hollow body 14 has a cylindrical shape, and the energy absorber 13 into which the inner hollow body 11 is inserted is disposed inside and is in contact with the energy absorber 13.
[0019]
The adhesive is a thermosetting type, and is used for fixing the energy absorber 13 and the outer hollow body 14. The adhesive is applied to, for example, a part or the entire outer peripheral surface of the energy absorber 13, and the energy absorber 13 is inserted into the outer hollow body 14 so that the gap between the energy absorber 13 and the outer hollow body 14 is formed. Placed in Since the adhesive is not applied to fix the energy absorber 13 and the inner hollow body 11, the material cost is reduced and the production cost is not increased.
[0020]
Therefore, when the double hollow body having the above configuration is contracted, the outer hollow body 14 and the energy absorber 13 are deformed. At this time, the adhesive is hardened by the heat generated by the deformation of the outer hollow body 14, and the outer hollow body 14 and the energy absorber 13 are fixed. Further, due to the deformation of the energy absorber 13, the porous metal constituting the energy absorber 13 protrudes so as to fit into the through hole 12, and the energy absorber 13 and the inner hollow body 11 are fixed.
[0021]
That is, the fixing of the outer hollow body and the energy absorber using the adhesive is performed at the same time as the fixing of the energy absorber and the inner hollow body. Therefore, a step for curing the adhesive is unnecessary, and the number of work steps and equipment costs do not increase, so that the production cost does not increase.
[0022]
As described above, in the present embodiment, it is possible to provide an energy absorbing member excellent in production cost and a method for forming the same.
[0023]
In addition, it is preferable to apply the spinning method to the contraction of the double hollow body from the viewpoint of production efficiency. In particular, when the double hollow body is cylindrical, a method in which the double hollow body is rotated and a roller is pressed to perform plastic working is preferable.
[0024]
Further, the adhesive can have a two-stage thermal curing history having a curing temperature that causes main curing and a pseudo-curing temperature that causes temporary curing (pregelling). In this case, the adhesive reaches a pseudo-curing temperature due to heat generated by deformation of the outer hollow body. Since the simulated curing temperature is lower than the curing temperature, only a small amount of heat generation due to the deformation of the outer hollow body is required. Therefore, the degree of freedom in operating conditions for contracting the double hollow body increases.
[0025]
The outer hollow body and the energy absorber are temporarily fixed by the heat generated by the deformation of the outer hollow body. Therefore, it is easy to stably maintain the outer hollow body and the energy absorber in a predetermined position until the step of finally hardening the adhesive and finally fixing the outer hollow body and the energy absorber. is there.
[0026]
An adhesive having a two-stage thermal curing history can be composed of an epoxy resin composition having excellent pseudo-curability and storage stability in a well-balanced manner. The epoxy resin composition is, for example, a powdery (meth) acrylate polymer A having a basic particle size of less than 5 μm and a powdery (meth) acrylate polymer having a basic particle size of 5 to 100 μm per 100 parts by weight of the epoxy resin. B can be prepared by adding 10 to 100 parts by weight of a mixture of B and A / B in a weight ratio range of 1/9 to 9/1. In addition, it is more preferable that the basic particle size of the (meth) acrylate polymer B is 20 to 50 µm.
[0027]
The pseudo-curing temperature of the adhesive having two-stage thermal curing history can be appropriately set depending on the combination of the epoxy resin, the curing agent, and the curing accelerator used for the adhesive. For example, when an amine-based curing agent is used, an adhesive having a pseudo-curing temperature of 60 ° C. or higher and a curing temperature of 150 ° C. or higher can be obtained.
[0028]
On the other hand, the vehicle body manufacturing process includes a step of baking a coating film formed by coating the vehicle body with a paint such as an electrodeposition paint. Therefore, when the energy absorbing member is used for an impact action portion of the vehicle body and, for example, the temperature for baking the electrodeposition paint is the same as the curing temperature of the adhesive, the step for baking the electrodeposition paint is performed. In the above, the adhesive can be fully cured to finally fix the outer hollow body and the energy absorber. Therefore, it is not necessary to add a step for fully curing the adhesive.
[0029]
FIG. 2 is a perspective view for explaining a method of forming the energy absorbing member according to the embodiment of the present invention.
[0030]
In addition, for the contraction of the double hollow body 10, a spinning method in which rollers 30 and 31 are pressed to perform plastic working is applied. Although the number of rollers applied to the spinning method is three, one is omitted for simplification of the drawing. The feed speed of the rollers 30, 31 is 1 mm / s. Note that if the amount of contraction is excessive, the double hollow body 10 will be cracked. Therefore, it is preferable to divide the contraction into a plurality of times as necessary to achieve the target dimensions. In this embodiment, The processing repetition is three passes.
[0031]
The inner hollow body of the double hollow body 10 is formed of a cylindrical steel pipe having a tensile strength of 490 MPa, a plate thickness of 1.0 mm, a diameter of 40 mm, and a total length of 500 mm. The energy absorber disposed outside the inner hollow body is a cylindrical body made of aluminum foam, has a dimension substantially equal to the outer peripheral dimension of the inner hollow body, and has a center axis substantially coincident with the outer hollow dimension. The through-hole of the inner hollow body has a diameter of 30 mm, which is six times the average cell size of the foamed aluminum.
[0032]
The outer hollow body 14 disposed outside the energy absorber is formed of a cylindrical steel pipe having a tensile strength of 490 MPa, a plate thickness of 1.6 mm, a diameter of 80 mm, and a total length of 500 mm. The adhesive disposed between the outer hollow body and the energy absorber has a two-stage thermal curing history in which the pseudo-curing temperature is 60 ° C or higher and the curing temperature is 150 ° C or higher.
[0033]
First, machine oil was applied as a lubricant to the outer periphery of the outer hollow body 14 constituting the surface of the double hollow body 10, and the double hollow body 10 was set between the rotary jigs 20 and 21. Next, the double hollow body 10 was contracted by rotating the double hollow body 10 and moving in the direction of the arrow while pressing the rollers 30 and 31 to perform plastic working.
[0034]
During this contraction, the outer hollow body 14 and the energy absorber were deformed. Then, due to the heat generated by the deformation of the outer hollow body 14, the temperature of the outer hollow body 14 reaches 70 ° C., which is higher than the pseudo-curing temperature of the adhesive, and the adhesive is temporarily cured, and the outer hollow body 14 and the energy absorber are separated. Temporarily fixed.
[0035]
On the other hand, due to the deformation of the energy absorber, the aluminum foam constituting the energy absorber protruded into the inner hollow body via the through-hole of the inner hollow body, and the aluminum foam fitted with the through-hole. As a result, the energy absorber and the inner hollow body were fixed.
[0036]
Next, the double hollow body 10 was subjected to a heat treatment under curing conditions (170 ° C. for 20 minutes) corresponding to the baking conditions of the coating film coated by electrodeposition coating. As a result, the adhesive disposed between the outer hollow body 14 and the energy absorber was fully cured, and the outer hollow body 14 and the energy absorber were finally fixed.
[0037]
In the obtained energy absorbing member, the outer hollow body 14 and the energy absorber are satisfactorily fixed by the adhesive, and the porous metal projecting from the through hole of the inner hollow body and the through hole are securely fitted. As a result, the energy absorber and the inner hollow body are firmly fixed.
[0038]
FIG. 3 is a graph showing the relationship between the contraction amount of the outer hollow body and the protruding length of the porous metal constituting the energy absorber when the size S of the through hole of the inner hollow body is changed.
[0039]
The size S of the through hole is standardized by the average cell size of the porous metal constituting the energy absorber. The amount of contraction of the outer hollow body is the rate of decrease in the distance between the outer periphery of the outer hollow body and the outer periphery of the inner hollow body before and after the contraction. The protruding length of the porous metal is a length of a portion protruding into the inside of the inner hollow body via a through hole of the inner hollow body. Note that, as the energy absorber, aluminum foam having an average cell size of 5 mm and a density of 0.24 g / cm ³ was used.
[0040]
As shown in the figure, when the size S of the through hole is twice as large as the average cell size of the porous metal, the protruding length of the porous metal is small, and the contraction amount of the outer hollow body is increased. However, the protrusion length of the porous metal does not significantly increase. Therefore, it is difficult to securely fix the energy absorber and the inner hollow body.
[0041]
On the other hand, the protrusion length of the porous metal increases as the size S of the through hole increases, and the protrusion length of the porous metal increases remarkably as the amount of contraction of the outer hollow body increases. To increase.
[0042]
In particular, when the size S of the through hole was four times the average cell size of the porous metal, the energy absorber and the inner hollow body could be fixed stably and reliably. When the size S of the through hole exceeds 10 times the average cell size of the porous metal, the amount of reduction in the contraction of the outer hollow body substantially coincides with the protruding length of the porous metal.
[0043]
Therefore, the through-hole preferably has an equivalent radius that is at least four times the average cell size of the porous metal. In this case, since the porous metal protrudes so as to securely fit into the through hole, the quality of fixing the energy absorber and the inner hollow body is improved.
[Brief description of the drawings]
FIG. 1 is an exploded view for explaining a configuration of an energy absorbing member according to an embodiment of the present invention.
FIG. 2 is a perspective view for explaining a method of forming an energy absorbing member according to the embodiment of the present invention.
FIG. 3 is a graph showing a relationship between a contraction amount of an outer hollow body and a protrusion length of a porous metal constituting an energy absorber when a size of a through hole of an inner hollow body is changed.
[Explanation of symbols]
10 double hollow body,
11 ... inner hollow body,
12 ... through-hole,
13 ... energy absorber,
14 ... outer hollow body,
20, 21 ... rotating jig,
30, 31 ... rollers.

Claims (11)

An inner hollow body having a through hole formed in the outer periphery, an outer hollow body into which the inner hollow body is inserted, and disposed between the inner hollow body and the outer hollow body, wherein the inner hollow body and the outer hollow body are disposed. A double hollow body having an energy absorber made of a porous metal in contact with both the body and a thermosetting adhesive disposed between the outer hollow body and the energy absorber;
By contracting the tube, the outer hollow body and the energy absorber are deformed,
By the heat generated by the deformation of the outer hollow body, the adhesive is cured, and the outer hollow body and the energy absorber are fixed,
By deforming the energy absorber, the porous metal constituting the energy absorber is projected so as to fit with the through hole, and the energy absorber and the inner hollow body are fixed. A method for forming an energy absorbing member. The method according to claim 1, wherein the double hollow body is contracted by a spinning method. The double hollow body is cylindrical,
3. The method according to claim 2, wherein the spinning method uses a roller that presses the rotating double hollow body to plastically process the double hollow body. 4. The method according to any one of claims 1 to 3, wherein the through hole has an equivalent radius that is at least four times an average cell size of the porous metal. The adhesive according to any one of claims 1 to 4, wherein the adhesive has a pseudo-curing temperature that causes temporary curing, and reaches the pseudo-curing temperature by heat generated by deformation of the outer hollow body. A method for forming an energy absorbing member. The energy absorbing member according to claim 5, wherein the adhesive contains a liquid epoxy resin and a heat-activated curing agent, and has a pseudo-curing temperature of 60C or more and a curing temperature of 150C or more. Formation method. The double hollow body has a cylindrical shape, and is rotated by rotating the double hollow body, and is compressed by a spinning method of performing plastic working by pressing a roller,
The adhesive contains a liquid epoxy resin and a heat-activated curing agent, the pseudo-curing temperature is 60 ° C or higher, and the curing temperature is 150 ° C or higher,
The method for forming an energy absorbing member according to claim 1, wherein the feed speed of the roller is 1 mm / s or more. The method for forming an energy absorbing member according to claim 1, wherein the energy absorbing member is used in an impact action portion of a vehicle body. The energy absorbing member is used in an impact action portion of a vehicle body,
The baking of a coating film coated on the vehicle body, the adhesive is fully cured, and the outer hollow body and the energy absorber are finally fixed. 3. The method for forming an energy absorbing member according to item 1. The method for forming an energy absorbing member according to claim 1, wherein the porous metal is made of a foamed metal. An energy-absorbing-portion blank formed using the method for forming an energy-absorbing member according to claim 1.

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