JP2005349990A - Method of forming metal foam composite member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming a metal foam filled composite member in which the composite member is formed by combining the metal foam and a structure member, it can be simply integrated with the structure member and strength required as the structure member can be stably ensured. <P>SOLUTION: In the method of forming the metal foam composite member, the composite member is formed by combining the molded metal foam 5 and a cylindrical thin-walled extrusion 4. Cylinder walls 2d, 2d are deformed such that a cross section in a direction perpendicular to a cylinder axis direction of the extrusion 4 gets smaller than the cross section of the metal foam 5, and the metal foam 5 is pressed-in the extrusion 4 in resistant to the deformed cylinder walls 2d, 2d. The metal foam 5 is fixed into the extrusion 4 utilizing restoration force of the cylinder walls 2d, 2d. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for forming a metal foam composite member suitable as a structural member such as a pillar constituting a vehicle body.

  Conventionally, structural members such as pillars that constitute a part of a vehicle body such as an automobile are generally formed of a cylindrical member that generally has a closed cross section. Reinforcement is performed by various methods for the purpose of increasing the strength and rigidity.

(a) Reinforcing method by increasing the section modulus For example, a method of reinforcing a cylindrical member by attaching a reinforcing material made of the same kind of metal, and reinforcing by adding a complicated shape in the length direction of the cylindrical member by press molding A method of applying partition ribs to the inner surface of the cylindrical member by die casting and reinforcing the inner surface of the cylindrical member, a method of reinforcing the cylindrical member by forming a cross section of the cylindrical member into a polygonal shape or a deformed cross section by extrusion molding, and the like.

(b) Reinforcing method by combining different materials The most common combination of different materials is filling with a resin foam.

  In the method of injecting and reacting a resin foam into a cylindrical member and causing it to foam, the cylindrical member is filled with resin and cured, whereby the cylindrical member and the resin foam expanded by foaming are integrated. However, this type of reinforcement method requires equipment for in-situ foaming of the resin foam material, and further requires strict temperature control of the resin foam material, so an increase in cost is inevitable. In that respect, a method of cutting a resin foam molded using a mold (hereinafter referred to as a molded resin foam) into a desired size and inserting it into a cylindrical member is easy to construct and reduces costs. There is an advantage that it can be planned.

  However, in order to attach the molded resin foam to the cylindrical member, means for fixing the molded resin foam inside the cylindrical member is required.

For this reason, a hook for fixing the molded resin foam is fixed to the inner wall of the cylindrical member, or a restriction plate for restricting the movement of the molded resin foam is disposed, for example, on both upper and lower sides of the molded resin foam. Although the molded resin foam is fixed, the adhesiveness as in the case of foaming by injecting the resin foam into the cylindrical member as described above is not obtained. If the adhesiveness with the cylindrical member is low, vibration occurs in the cylindrical member, and a reinforcing effect cannot be obtained. Therefore, at present, a resin elastic layer is interposed in the gap between the cylindrical member and the molded resin foam inserted therein, and the molded resin foam is fixed using the compression reaction force of the resin elastic layer. It is devised to ensure (see, for example, Patent Document 1).
JP 2000-318075 A

  In the reinforcing method (a), a process for providing various shapes and processing accuracy are required, and there is a problem that costs are increased if a dedicated molding die is prepared.

  Further, in the reinforcing method using the molded resin foam of (b) above, it is difficult to completely fix the molded resin foam in the cylindrical member, and the adhesion between them cannot be improved, so that a reinforcing effect is obtained. There is a problem that it is difficult to get.

  The present invention has been made in consideration of the problems in the conventional structural members for vehicle bodies as described above. The metal foam is combined with the structural member to form a composite member, and can be easily integrated with the structural member. It is possible to provide a method for forming a metal foam composite member capable of stably securing the strength required as a structural member.

  The present invention that solves the above-mentioned problems is to provide the adhesion between the shape material and the metal foam in the interior of the molded metal foam in the inner space of the thin-walled cylindrical shape that finally forms the closed section. A composite member having increased rigidity by being increased is provided, and there are two forms of forming methods.

  A first aspect of the present invention is a method for forming a metal foam composite member in which a composite member is formed by combining a molded metal foam and a thin cylindrical shape, and is orthogonal to the cylinder axis direction of the shape. The cylinder wall is deformed so that the cross section in the direction is smaller than the cross section of the metal foam, and the metal foam is press-fitted into the shape against the deformed cylinder wall, and the restoring force of the cylinder wall is used. The metal foam composite member is formed by fixing the metal foam in the shape member.

  According to the first aspect of the present invention, since the cylindrical wall of the shape is deformed to function as a spring capable of accumulating the urging force, the metal foam is not contained in the shape without requiring any special fixing means. It can be easily fixed to.

  In the first aspect of the present invention, when the profile consists of a U-shaped main body and a lid for closing the opening of the main body, the cylinder is formed by applying external pressure to the parallel wall surface of the main body. The wall can be deformed. In this case, the adhesion between the profile and the metal foam is proportional to the size of the area of external pressure applied to the profile.

  The second aspect of the present invention is a metal foam composite member forming method in which a composite member is formed by combining a molded metal foam and a thin cylindrical shape, and can be fitted into the shape. This is a method for forming a metal foam composite member in which a metal foam having a size is formed and the contact surface between the metal foam and the profile is fixed by a joining means.

  According to the second aspect of the present invention, the metal foam can be firmly fixed in the profile.

  An adhesive can be used as the joining means. In addition, as a joining means, a heat fusion sheet is interposed between the metal foam and the shape, and the heat fusion sheet is dissolved by heating to be fused to both the metal foam and the shape. The metal foam and the profile can also be fixed by solidifying.

  If the said heat sealing | fusion sheet | seat is used, since the melt | dissolved heat sealing | fusion sheet | seat adheres to a shape material and a metal foam and fills the clearance gap between both, both are fixed reliably.

  Further, if a brazing material sheet is used as the heat-sealing sheet, it can be provided on the entire inner wall of the shape member, and can also be partially provided at a portion where high rigidity is required. In short, the attachment part of the brazing material sheet may be determined appropriately according to the required specifications.

  In the first and second aspects of the present invention, the metal foam is used in order to eliminate the decrease in strength due to secular change and to improve the recyclability for effective use of earth resources. It is. Moreover, the composite member using a metal foam is known to absorb vibrations and electromagnetic waves, and has an advantage that it can not only increase rigidity but also add added value.

  Further, the reason why the molded metal foam is used in the present invention is to eliminate the large-scale equipment that is unavoidably introduced when foaming from the molten state is performed, and this is eliminated.

  According to the method for forming a metal foam composite member of the present invention, the metal foam can be easily fixed and integrated in the shape member, and the strength required as a structural member can be stably secured. Has the advantage of being able to.

  In addition, since the rigidity of the composite member is increased by improving the adhesion between the metal foam and the shape member, when the composite members having the same rigidity are compared, the present invention can reduce the cross section. As a result, for example, when applied to the center pillar of an automobile, there is an advantage that visibility is improved as much as a smaller cross section is achieved.

  Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings.

  FIG. 1 is a cross-sectional view showing a configuration of a metal foam composite member obtained by the forming method of the present invention.

  In the figure, a metal foam composite member 1 is closed by closing a hat material (main body portion) 2 obtained by pressing a thin aluminum plate having a thickness of 1 mm into a convex shape and a lower opening portion of the hat material 2. It is comprised from the profile 4 formed in the cylinder shape with the baseplate (lid part) 3 which forms a cross section, and the metal foam 5 inserted in this profile 4.

  Flange portions 2a and 2a extending in the horizontal direction are provided on the skirt side of the hat material 2, and the flange portions 2a and 2a and the bottom plate 3 are spot-welded and joined at a predetermined pitch. Note that the method of joining the flange portion 2a and the bottom plate 3 is not limited to this, and may be mechanical joining using rivets or chemical joining using an adhesive.

  Further, the left and right shoulder portions 2b, 2b of the hat material 2 are rounded respectively.

  The metal foam 5 uses foamed aluminum in this embodiment. Foamed aluminum is expected to be used as a structural member because it is ultralight and has excellent impact energy absorption performance. However, foamed aluminum alone has low rigidity and is considered to be used in combination with other members.

In the present embodiment, foamed aluminum having a density of 250 kg / m ³ or less is manufactured, and the molded metal foam block is cut into a length of 50 mm × width of 50 mm × length of 600 mm to obtain a metal foam 5.

  FIG. 2 shows a method of forming the metal foam composite member 1 shown in FIG.

  In FIG. 6A, an external force in the direction of arrow A is applied to the skirt portion 2c of the hat material 2 from both the left and right sides so that the side walls (cylinder walls) 2d and 2d of the hat material 2 are each at θ ° from the vertical line VL. It is deformed to incline inward and gives permanent strain. Thereby, the cross section in the direction orthogonal to the cylinder axis direction of the profile 4 is deformed so as to be smaller than the cross section of the metal foam 5.

  Next, the metal foam 5 is press-fitted in the direction of arrow B from the opening of the hat material 2 as shown in FIG. At this time, the metal foam 5 enters the hat material 2 while spreading both side walls 2d, 2d of the hat material 2.

  Since the both side walls 2d and 2d spread by the metal foam 5 have a restoring force to return to the inclined state shown in FIG. 2 (a), the left and right side walls 5a and 5a of the metal foam 5 are thereby generated. Is held by both side walls 2d, 2d and fixed in close contact with the hat material 2. The fixed state is as shown in FIG.

  In the metal foam composite member 1 described above, the hat member 2 and the metal foam 5 are coupled together by the spring action of the side walls 2d and 2d.

  The magnitude of the restoring force is adjusted to a value at which the metal foam 5 does not undergo plastic deformation. Specifically, the metal foam 5 used in the present embodiment is an ultralight material having a porosity of 90% or more, and generally has a low strength. Therefore, if the restoring force generated by applying an external force to the hat material 2 is too large, the metal foam 5 is plastically deformed. Therefore, an external force is applied to the hat material 2 so that the restoring force for fixing the metal foam 5 is 2 MPa at the maximum.

  Next, a method of forming the metal foam composite member by fixing the hat member 2 and the metal foam 5 with an adhesive will be described.

  In this case, for example, a silicon adhesive is applied to the inner surface of the hat member 2, and then the metal foam 5 is fitted into the hat material 2, and the metal foam 5 and the hat material 2 are fixed by curing the adhesive. .

  The bending rigidity of each metal foam composite member thus configured was tested.

The bending rigidity EI is expressed by the following equation assuming a simple support beam of material mechanics shown in FIG.
EI = [1/48] · [P / δmax] · L ³
Here, E is the flexural modulus, I is the secondary moment of section, P is the load, δmax is the maximum deflection, and L is the length of the beam.

  From the load P and the maximum deflection amount δmax in the bending elastic region, as shown in Table 1, when (a) the rigidity of only the hat member 2 not provided with the metal foam is 1, (b) the metal foam 5 is simply The composite member just inserted is 1.4 times, (c) The composite member in which the metal foam 5 is press-fitted by deforming the side walls 2d and 2d of the hat material 2 by applying external pressure is 1.7 times, and (d) the metal foam The composite member in which the body 5 was bonded to the hat material 2 with an adhesive was 2.3 times more rigid.

  This shows that the bending rigidity increases as the adhesion between the metal foam 5 and the hat material 2 improves.

  The adhesion between the metal foam 5 and the hat material 2 is not limited to the organic adhesive described above, and a heat fusion sheet (not shown) can also be used. In this case, a heat-fusion sheet is interposed between the metal foam 5 and the hat material 2, and the heat-fusion sheet is dissolved by heating to adhere to both the metal foam 5 and the hat material 2. The metal foam 5 and the hat material 2 are fixed by solidifying.

  In addition, a metal sheet having a low melting point, for example, a brazing material sheet can be used as the heat-sealing sheet, and the brazing material sheet is disposed between the outer surface of the metal foam 5 and the inner surface of the hat material 2 to instantaneously If only the brazing material sheet is dissolved by heating and then solidified immediately, the metal foam 5 and the hat material 2 can be completely fixed.

  Next, FIG. 4 and FIG. 5 show a modification of the shape member 4 that uses the restoring force by applying external pressure.

  The shape member 4 shown in FIG. 4 is composed of overlapping hat members 6 and 7.

  Each of the hat materials 6 and 7 has basically the same configuration as the hat material 2 described above, and the upper hat material 6 is formed with flange portions 6a and 6a, and the lower hat material 7 has its flange portion 6a. , 6b, flange portions 7a, 7a are formed.

  When the metal foam 8 is inserted into the overlapping hat members 6 and 7, first, the side walls 6b and 6b of the upper hat material 6 are pushed open in the left-right direction, and the upper half of the metal foam 8 is press-fitted, and then the lower Similarly, the side walls 7b and 7b of the side hat material 7 are pushed open in the left-right direction, the lower half of the metal foam 8 is press-fitted, and the opposing flange portions 6a and 7a are joined by spot welding to form a foam composite member. The

  FIG. 5 shows an example in which a metal foam composite member is formed by using an extruded material 9 having a closed cross section that is extruded as a profile.

  When the extruded material 9 is used, the wall surface is deformed by applying an external pressure so that the cross section is smaller than the cross section of the metal foam 10. For example, the side walls 9a and 9b are pressed and curved inward.

  Next, the metal foam 10 is press-fitted while expanding the curved side walls 9a and 9b. However, when the metal foam 10 is press-fitted, for example, an expansion member for pushing the side walls 9a and 9b outwardly is inserted in advance of the metal foam 10, and it is necessary to remove the metal foam 10 while it is inserted. There is.

  In the above embodiment, (c) a method of applying external pressure to deform the side wall of the hat material and gripping the metal foam with a restoring force, and (d) a metal foam with a joining means (adhesive, brazing material sheet). Although the method of bonding to the hat material has been shown, the above methods (c) and (d) are combined, that is, if the adhesive surface of the metal foam and the hat material is gripped by the restoring force of the hat material side wall, Both can be fixed in a state in which the adhesion between the metal foam and the hat material is further improved.

It is sectional drawing of the metal foam composite member to which the formation method of this invention was applied. (a) And (b) is explanatory drawing which shows the formation method of the metal foam composite member of FIG. It is a figure of the beam for calculating the bending rigidity of the metal foam composite member of this invention. It is FIG. 1 equivalent view which shows the modification of the shape material of this invention. FIG. 6 is a view corresponding to FIG. 1 showing another modification of the shape member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal foam composite member 2 Hat material 2a Flange part 2c Bottom part 2d Side wall 3 Bottom plate 4 Shape material 5 Metal foam 5a, 5b Side wall

Claims (6)

In the method of forming a metal foam composite member that forms a composite member by combining a molded metal foam and a thin cylindrical shape,
The cylindrical wall is deformed so that a cross section in a direction perpendicular to the cylindrical axis direction of the profile is smaller than a cross section of the metal foam, and the metal foam is deformed against the deformed cylindrical wall. A method for forming a metal foam composite member, wherein the metal foam is fixed in the shape member by press-fitting into the shape member and utilizing the restoring force of the cylindrical wall.   The profile comprises a main body portion having a U-shaped cross section and a lid portion that closes the opening of the main body portion, and deforms the cylindrical wall by applying external pressure to the parallel wall surface of the main body portion. The method for forming a metal foam composite member according to claim 1. In the method of forming a metal foam composite member that forms a composite member by combining a molded metal foam and a thin cylindrical shape,
A method for forming a metal foam composite member, comprising forming the metal foam having a size that can be fitted into the shape material, and fixing a contact surface between the metal foam and the shape material with a joining means. .   4. The method for forming a metal foam composite member according to claim 3, wherein an adhesive is used as the joining means.   As the joining means, a heat fusion sheet is interposed between the metal foam and the shape material, and the heat fusion sheet is melted by heating and fused to both the metal foam and the shape material. 4. The method of forming a metal foam composite member according to claim 3, wherein the metal foam and the shape member are fixed by solidifying and solidifying the metal foam. 6. The method for forming a metal foam composite member according to claim 5, wherein a brazing material sheet is used as the heat-sealing sheet.

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