JP2005029064A - Energy absorption member for aluminum alloy automobile frame and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lightweight energy absorption member for an aluminum alloy automobile frame with high energy absorbing capacity capable of surely absorbing impact energy being stably sequentially subjected to buckling deformation from an end part when receiving an impact load, and a manufacturing method thereof. <P>SOLUTION: The energy absorption member is composed of a hollow shape material made of tempered, heat-treated aluminum alloy and provided with recessed/projected parts formed in a lateral direction of the shape material at least in part of the shape material in a longitudinal direction to be a starting point of bellow-shaped deformation of the shape material when compression stress is applied in the longitudinal direction of the shape material by bending a wall face of the hollow shape material outward or inward. Depth of the recessed/projected part is 7 to 25 mm, the maximum compressive load under a static compressive load in the longitudinal direction is 75 to 180 kN, the average compressive load is 60 to 150 kN, and a ratio of the average compressive load / the maximum compressive load is 0.87 or more. The recessed/projected part is formed by applying a compression amount of 7 to 15 mm in the longitudinal direction of the shape material. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an energy absorbing member for an automobile frame made of an aluminum alloy, and more particularly, to an aluminum alloy hollow member attached to a superstructure of a vehicle body in order to absorb the collision energy when the automobile collides to ensure the safety of a passenger. The present invention relates to an energy absorbing member for a vehicle frame made of a profile and a method for manufacturing the same.

  Conventionally, an energy absorbing member for protecting a passenger by absorbing energy at the time of a collision is formed into a box shape by press-molding a steel plate material and spot welding or the like. When this member receives a compressive load in the vertical direction due to an impact, as shown in the compressive load-member displacement diagram of FIG. 11, when the maximum compressive load is reached, the load decreases rapidly, and the bellows starts from the end of the member. The plastic buckling proceeds and absorbs impact energy. In this case, the higher the average compressive load (hereinafter simply referred to as the average load) in the compressive load-member displacement diagram, the more energy can be absorbed, while the maximum compressive load (hereinafter simply referred to as the maximum load). Is too high, the rear end of the energy absorbing member is deformed before the energy absorbing member is deformed into a bellows shape. Therefore, the higher the average load / maximum load ratio, the better the energy absorbing member.

  In order to realize such an energy absorption mode, when a collision load is applied to the steel plate box-shaped member, a bellows-like buckling deformation must be surely caused from the load-load end portion of the member. For this purpose, a design technique for providing a bead portion or a hole portion in a steel plate box-shaped member to promote buckling has been studied (see Non-Patent Document 1).

  In recent years, reduction of automobile body weight has been proposed due to environmental problems, and the impact energy absorbing member, which is a body component, also requires a lighter and higher energy absorbing member in place of the conventional steel plate box member. In order to satisfy this requirement, the use of aluminum alloys has been studied. For energy absorbing members using aluminum alloy hollow shape members, the wall surfaces of the shape members are bent to the outer surface or the inner surface to form grooves and impact. It has been proposed by the inventors to increase the ratio of the average load / maximum load by deforming the bellows with the compression load of time (see, for example, Patent Document 1).

The above-mentioned groove can also be formed by applying a compressive load in the length direction of the shape in advance. For this purpose, a method using a jig for restraining the bending of the shape wall (see Patent Document 2) Proposals have also been made on the form of grooves for inducing regular bellows deformation (see Patent Document 3).
Mitsubishi Heavy Industries Technical Review, Vol.8, No.1, pp. 124-130 JP-A-7-145842 (claims, 0006) JP 2000-238659 A (Claims) JP-A-8-21617 (claim)

  However, the conventional energy absorbing member described above has a small depth of grooves (irregularities) generated by bending deformation, and stable bellows deformation may not be expected due to a compressive load at the time of impact. Moreover, although the ratio of average load / maximum load is prescribed | regulated as 0.5 or more by the said patent document 1, as seen also in the Example, it is 0.54-0.85 substantially. It has been experienced that it is not always sufficient to cause plastic buckling to proceed by bellows deformation at the time of impact and to absorb impact energy reliably.

  In order to eliminate the above-mentioned conventional difficulties, the present invention is based on the invention described in Patent Document 1 by the inventors, and has an uneven portion (groove) for reliably causing bellows deformation by a compressive load at the time of impact. It was made as a result of further examination on the limit of the ratio of the average load / maximum load in order to advance the plastic buckling by the bellows deformation at the time of impact, and to absorb the impact energy reliably. An object is an energy absorbing member for an automobile frame made of an aluminum alloy that is light weight, has high energy absorption, and stably buckles and deforms sequentially from the end when receiving an impact load, and reliably absorbs impact energy, and a method for manufacturing the same. Is to provide.

In order to achieve the above object, an energy absorbing member for an aluminum alloy automobile frame according to claim 1 of the present invention comprises a tempered heat-treated aluminum alloy hollow member, and the thickness of the hollow member is 1. above 8 mm, provided the total sectional area including the hollow portion of the hollow profile is 3000～8000Mm ^2, hollow portion each of the cross-section of the hollow profile has a cross-sectional area of 1000～4000Mm ² is one or more And at least a part of the shape in the length direction of the shape, the wall of the hollow shape that can be a starting point for the bellows-like deformation of the hollow shape when the compressive stress is applied in the length direction of the hollow shape. The uneven part formed by bending is formed in the transverse direction of the hollow shape member, and the depth of the uneven part is 7 to 25 mm.

  The energy absorbing member for an automobile frame made of aluminum alloy according to claim 2 is the energy absorbing member for an automobile frame according to claim 1, wherein the maximum load is 75 to 180 kN, the average load is 60 to 150 kN, and the average load / The maximum load ratio is 0.87 or more.

  The energy absorbing member for an aluminum frame made of an aluminum alloy according to claim 3 is the energy absorbing member for an automobile frame according to claim 1 or 2, wherein, in the concavo-convex portion, a maximum bent portion having a maximum depth from the wall surface of the hollow shape member is a hollow shape member. It is formed in the position of 40 +/- 15mm from the collision side edge part in a length direction.

  According to a fourth aspect of the present invention, there is provided a method of manufacturing an energy absorbing member for an automobile frame made of aluminum alloy, wherein the concave and convex portions are formed by applying a compression amount of 7 to 15 mm in the length direction of the hollow shape member. .

  According to a fifth aspect of the present invention, there is provided a method for manufacturing an energy absorbing member for an aluminum alloy automobile frame according to the fourth aspect, wherein a wall surface of the hollow shape member is bent to the inner surface side by a punch at an arbitrary position in the length direction of the hollow shape member. Then, the concave and convex portions are formed at the arbitrary positions by giving a compression amount in the length direction of the hollow shape member.

  According to a sixth aspect of the present invention, there is provided a method for manufacturing an energy absorbing member for an automobile frame made of an aluminum alloy according to the fifth aspect, wherein the wall surface of the hollow shape member is moved to the inner surface side by a punch at an arbitrary position in the length direction of the hollow shape member. It is characterized by forming a concavo-convex portion at the above-mentioned arbitrary position by giving a compression amount in the length direction of the hollow shape member after being bent 0.5 mm to 5.0 mm.

  According to a seventh aspect of the present invention, there is provided a method for producing an energy absorbing member for an aluminum alloy automobile frame according to any one of the fourth to sixth aspects, wherein a jig for restraining the bending of the wall surface is provided at the upper and lower portions in the length direction of the hollow shape member. By arranging and giving a compression amount in the length direction of the hollow shape member, an uneven portion is formed at an arbitrary position where the bending of the wall surface in the length direction of the hollow shape material is not constrained.

  According to the present invention, an aluminum frame made of an aminium alloy that is light in weight, has a high energy absorption rate, and can stably buckle and deform from the end portion in a stable manner when receiving an impact load, thereby securely absorbing the impact energy. An energy absorbing member and a method for manufacturing the same are provided. The energy absorbing member for an automobile frame made of aminium alloy according to the present invention can be easily welded to an automobile body, and can be applied as a front and rear side member, a steering shaft, a side door / impact member, etc. of an automobile.

The energy absorbing member for an automobile frame made of aluminum alloy according to the present invention is made of a tempered heat-treated aluminum alloy hollow member, and the hollow member has a wall thickness of 1.8 mm or more and includes a hollow part of the hollow member. the total cross section is 3000～8000Mm ^2, a hollow portion having a cross-sectional area of each of the cross-section 1000～4000Mm ² of the hollow profile is assumed that provided one or more, at least the hollow profile A part of the length direction is formed by bending the wall surface of the hollow shape member that can be a starting point of bellows-like deformation of the hollow shape member to the outer surface or the inner surface when compressive stress is applied in the length direction of the hollow shape member. The uneven portion is formed in the transverse direction of the shape member, and the depth of the uneven portion is 7 to 25 mm.

  As shown in FIGS. 1-3, the uneven | corrugated | grooved part 2 is provided in the arbitrary places of the length direction of the aluminum alloy hollow shape material 1, and was formed by bending the wall surface of the hollow shape material 1 to an outer surface or an inner surface. Yes, the depth D of the uneven portion is defined as shown in FIG.

  The depth D of the concavo-convex portion 2 is preferably 7 to 25 mm. By forming the concavo-convex portion depth within this range, the ratio of average load / maximum load can be improved. If it is less than 7 mm, the amount of decrease in the maximum load becomes small, and the ratio of average load / maximum load cannot be made 0.87 or more. If it exceeds 25 mm, a hollow shape member is attached as an energy member for an automobile frame. As a result, the uneven portion is likely to be a hindrance. A more preferable range of the depth of the uneven portion is 10 to 20 mm.

For example, an Al—Zn—Mg alloy or an Al—Mg—Si alloy is applied as the heat-treatable aluminum alloy constituting the hollow member of the present invention. These aluminum alloys are preferably subjected to T5 treatment or T6 treatment as tempering after extrusion. The hollow profile, wall thickness 1.8mm or more, the total cross-sectional area that includes a hollow portion in 3000～8000Mm ^2, 1, two or more hollow portion having a cross-sectional area of 1000～4000Mm ² is provided A round tube, a square tube, etc. are used suitably. If the thickness of the hollow shape material is less than 1.8 mm, extrusion itself is difficult, and the energy absorption characteristics deteriorate because the thickness is thin. When the total cross-sectional area of the hollow portion is less than 3000 mm ² , the substantial cross-sectional area of the shape member becomes small regardless of the cross-sectional area of the hollow portion, and the energy absorption characteristics are deteriorated. Even if the cross-sectional area of the hollow portion is increased beyond 4000 mm ² , the substantial cross-sectional area of the profile is reduced and the energy absorption characteristics are deteriorated.

On the other hand, even if the total cross-sectional area including the hollow part is increased beyond 8000 mm ² , a significant improvement in energy absorption characteristics due to a substantial increase in the cross-sectional area of the profile cannot be expected, and the weight increases. It becomes impractical as an energy absorbing member for a frame. Similarly, when the cross-sectional area of the hollow portion is less than 1000 mm ² , a significant improvement in energy absorption characteristics accompanying a substantial increase in the cross-sectional area of the profile cannot be expected, and the weight increases. It becomes impractical.

  The present invention also provides an uneven portion that can be a starting point for bellows-like deformation of a hollow shape when compressive stress is applied in the length direction of the hollow shape, and when a static compression load is applied in the length direction. The maximum load is 75 to 180 kN, the average load is 60 to 150 kN, the average load / maximum load ratio is 0.87 or more, and the average load / maximum load ratio is 0.87 or more. By doing so, plastic buckling progresses due to bellows deformation at the time of impact, and impact energy can be reliably absorbed.

  In the production of the energy absorbing member for an aluminum alloy automobile frame according to the present invention, a compression amount of 7 to 15 mm is applied by the pressing jig 3 in the length direction of the hollow member 1 as shown in FIGS. This is done by forming the concave and convex portion 2. Before giving the amount of compression, the wall surface of the hollow profile may be bent to the inner surface side by a punch.

  If the amount of compression is less than 7 mm, the depth D of the concavo-convex portion formed by bending becomes small, the amount of decrease in the maximum load becomes small, and the ratio of average load / maximum load cannot be 0.87 or more. When the compression amount exceeds 15 mm, the depth of the uneven portion formed by bending increases, and the uneven portion becomes an obstacle when mounting the hollow shape material as an energy absorbing member for an automobile frame, and the time required for compression is long. As a result, mass productivity decreases. A more preferable range of the compression amount is 10 to 15 mm.

  In the concavo-convex portion, it is desirable that the maximum bent portion having the maximum depth from the wall surface of the hollow shape member is formed at a position of 40 ± 15 mm from the collision side end portion in the length direction of the shape member. In the case where the concavo-convex portion is formed at a position closer than the position of 25 mm from the collision-side end portion in the length direction of the hollow shape member, a problem occurs when the end portion of the hollow shape member and another member are joined. When the concave and convex portion is formed at a position far from the position of 55 mm from the collision side end in the length direction of the hollow shape member, an ideal deformation form in which impact energy is absorbed by deforming bellows from the vicinity of the collision side is obtained. It becomes difficult.

  As shown in FIGS. 6 to 7, jigs 4 and 4 for restraining the bending of the wall surface are arranged at the upper and lower portions in the length direction of the hollow shape member 1, and pressure is applied in the length direction of the hollow shape member 1. By providing the compression amount with the jig 3, the uneven portion 2 can be formed at an arbitrary position where the bending of the wall surface in the length direction of the shape member is not constrained.

  In the production of an energy absorbing member for an automobile frame made of aluminum alloy according to the present invention, at any position in the longitudinal direction of the hollow shape member, at least one part of the wall surface of the hollow shape material, and the wall surface of the hollow shape material by a punch. After the inner surface is pushed and bent, the concave and convex portions can be formed at the arbitrary positions by giving a compression amount in the length direction of the hollow shape member. The shape of the punch and the method of fixing the hollow member when the punch is pushed in are not particularly limited, but the bending depth of the hollow member by pushing the punch is preferably 0.5 to 5.0 mm. When the bending depth is smaller than 0.5 mm, when the amount of compression is given in the length direction of the hollow shape member, it is not possible to form an uneven portion at an arbitrary position, and when the bending depth exceeds 5.0 mm. When the punch is pushed in, the hollow shape material is easily cracked and the energy absorption characteristics are deteriorated.

  Examples of the present invention will be described below in comparison with comparative examples. In addition, these Examples show one embodiment of this invention, and this invention is not limited to these.

An aluminum alloy billet containing Si: 0.45% (mass%, the same applies hereinafter), Fe: 0.20%, Mn: 0.04%, Mg: 0.65%, and the balance Al and impurities is extruded. Extrusion was performed at a temperature of 480 ° C. into a Japanese letter shape (a hollow cross-sectional shape having two hollow portions symmetrical to the partition wall with a partition wall at the center in the long side direction of the rectangle). The total cross-sectional area including the hollow part was 7100 mm ² , and the cross-sectional areas of the two hollow parts were both 2850 mm ² . The obtained hollow shape material was subjected to T6 tempering and used as a test material.

  From the obtained test material, a comparative test material and an inventive test material were produced by the following method.

  Comparative test material: A test material cut to a length of 300 mm.

  Invention test material 1: A test material is cut into a length of 310 mm, and a 10 mm deep concave / convex portion is formed by applying a compression amount of 10 mm in the length direction.

  Invention test material 2: A test material was cut into a length of 307 mm, and a 7 mm deep uneven portion was formed by applying a compression amount of 7 mm in the length direction.

  Invention test material 3: Cut the test material to a length of 310 mm, bend the wall surface to the inner surface side by a depth of 2 mm at a position 40 mm from the end, and then give a compression amount of 10 mm in the length direction Formed an uneven part with a depth of 10 mm.

  Invention test material 4: The test material is cut into a length of 310 mm, and as shown in FIGS. 8 to 9, jigs 4 and 4 for restraining the bending of the wall surface are arranged in a range of 20 mm from the upper end and 240 mm from the lower end. Then, an uneven portion having a depth of 10 mm is formed by giving a compression amount of 10 mm in the length direction.

  The comparative test material and the inventive test materials 1 to 4 were subjected to a static axial compression test at a test speed of 1 mm / sec. Each test material was placed on a base of an Instron universal testing machine, a compression load was applied by the pressure plate, and a load-displacement diagram applied to the pressure plate was recorded. As long as it is possible to apply a compressive load to the tester used, the same result can be obtained regardless of the tester used. If the contact surfaces are parallel, it has been confirmed that similar results can be obtained regardless of the shape.

  The test results are shown in Table 1, and the obtained load-displacement diagram is shown in FIG. As shown in Table 1, the average load of the comparative test material in which the uneven portion was not formed and the inventive test materials 1 to 4 were substantially equal. Further, as seen in FIG. 10, in the inventive test material, the peak load generated in the initial stage of the axial compression test is extremely low, and the maximum load is greatly reduced. Therefore, the ratio of the average load / maximum load of the inventive test material was as very large as 0.87 or more, and it was confirmed that it had excellent energy absorption characteristics.

It is a figure which simplifies and shows the Example of the uneven | corrugated | grooved part of the hollow shape material used for this invention. It is a figure which simplifies and shows other Examples of the uneven | corrugated | grooved part of the hollow shape material used for this invention. It is a figure which shows the cross section of the uneven | corrugated | grooved part formed in the hollow shape material of FIG. It is a figure before compression of the Example of the uneven | corrugated | grooved part formation process by compression of a hollow shape material. It is a figure after compression of the Example of the uneven | corrugated | grooved part formation process by compression of a hollow shape material. It is a figure before the compression of the other Example of the uneven | corrugated | grooved part formation process by compression of a hollow shape material. It is the figure after compression of the other Example of the uneven | corrugated | grooved part formation process by compression of a hollow shape material. It is a figure before compression of the uneven | corrugated | grooved part formation process in the invention test material 4. FIG. It is the figure after compression of the uneven | corrugated | grooved part formation process in the invention test material 4. FIG. It is a load-displacement diagram in the static axial compression test of the invention test material 1. It is a load-displacement diagram in the static axial compression test of the conventional energy absorption member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aluminum alloy hollow shape 2 Uneven part 3 Pressurizing jig 4 Restraint jig D Uneven part depth

Claims (7)

It consists of a tempered heat-treatable aluminum alloy hollow profile, the thickness of the hollow profile is 1.8 mm or more, and the total cross-sectional area including the hollow part of the hollow profile is 3000 to 8000 mm ^2. the hollow portion having a cross-sectional area of 1000～4000Mm ² each are provided one or more in cross-section, a portion of the length direction of at least the hollow shape member is a compressive stress in the longitudinal direction of the hollow frame member The uneven portion formed by bending the wall surface of the hollow shape member to the outer surface or the inner surface, which can be the starting point of the bellows-like deformation of the hollow shape member, is formed in the lateral direction of the hollow shape member, and the depth of the uneven portion is An energy absorbing member for an automobile frame made of an aluminum alloy, wherein the length is 7 to 25 mm. The maximum compression load when a static compression load is applied in the length direction is 75 to 180 kN, the average compression load is 60 to 150 kN, and the ratio of average compression load / maximum compression load is 0.87 or more. The energy absorbing member for an aluminum alloy automobile frame according to claim 1. In the concavo-convex portion, the maximum bent portion having the maximum depth from the wall surface of the hollow shape member is formed at a position of 40 ± 15 mm from the collision side end portion in the length direction of the hollow shape member. The energy absorbing member for an aluminum alloy automobile frame according to claim 1 or 2. The uneven part is formed by giving a compression amount of 7 to 15 mm in the length direction of the hollow shape member, wherein the energy absorbing member for an aluminum alloy automobile frame according to any one of claims 1 to 3 is formed. Production method. At any position in the length direction of the hollow shape member, the wall surface of the hollow shape member is bent to the inner surface side by a punch, and then given a compression amount in the length direction of the hollow shape member, the arbitrary position The method for producing an energy absorbing member for an aluminum alloy automobile frame according to claim 4, wherein uneven portions are formed on the aluminum alloy. At an arbitrary position in the length direction of the hollow profile, the wall surface of the hollow profile is bent 0.5 to 5.0 mm toward the inner surface by a punch, and then a compression amount is given in the length direction of the hollow profile. The uneven | corrugated | grooved part is formed in the said arbitrary positions by this, The manufacturing method of the energy absorption member for aluminum alloy vehicle frames of Claim 5 characterized by the above-mentioned. By placing jigs for restraining the bending of the wall surface at the upper and lower portions in the length direction of the hollow shape member, and applying a compression amount in the length direction of the hollow shape member, the wall surface in the length direction of the hollow shape member The method for manufacturing an energy absorbing member for an aluminum alloy automobile frame according to any one of claims 4 to 6, wherein the uneven portion is formed at an arbitrary position where the bending of the aluminum alloy is not restricted.