JP2010069927A - Method for manufacturing bumper structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve various problems with aging treatment of a bumper structure after joining a bumper reinforcement to a stay raw material using electromagnetic formation to form the bumper structure, for example, low aging treatment efficiency (too many spaces generated when a plurality of stacks are made in a furnace) and low precision after the aging treatment. <P>SOLUTION: A pipe-like 6000 series aluminum alloy extrusion material is expanded in its diameter by electromagnetic formation with a quality type T1 and the stay raw material 24 having a mounting flange 11 fixed on a front end of a side member is formed on the rear end. After the stay raw material 24 is subjected to aging treatment for a quality type T5, the stay raw material 24 is fitted into holes 7, 8 formed in vertical walls 3, 4 at the front and rear of the bumper reinforcement 1 formed from a 7000 series aluminum alloy extrusion material of the quality type T5 from the rear side. A pipe portion positioned on the forward side from around the vertical wall 4 on the rear side is expanded in its diameter and both of them are joined to each other. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention forms a hole penetrating in the front-rear direction at the left and right ends of a bumper reinforcement made of an aluminum alloy, and inserts a cylindrical stay material into the hole, expands the tube by electromagnetic forming, and forms an inner peripheral surface of the hole. The present invention relates to a method of manufacturing a bumper structure including a bumper reinforcement and a stay by being adhered to the bumper reinforcement.

  In Patent Document 1, a hole penetrating in the front-rear direction is formed in the front and rear walls of the left and right ends of a bumper reinforcement made of an aluminum alloy extruded material having a hollow cross section, and a cylindrical stay material is inserted into the hole to perform electromagnetic forming. And a bumper reinforcement comprising a bumper reinforcement and a stay to manufacture a bumper structure, which is in close contact with the inner peripheral surface of the hole and bonded to the bumper reinforcement.

  In Patent Document 1, for example, in the method shown in FIG. 5, an aluminum alloy extruded material cut into a predetermined size is used as a stay material as it is, and when the stay material is joined to the bumper reinforcement by expanding the tube by the electromagnetic forming, A mounting flange fixed to the front end of the side member is formed at the rear end. For example, in the method shown in FIG. 6, an aluminum alloy extruded material cut to a predetermined dimension is expanded in advance by electromagnetic forming to form a mounting flange fixed to the front end of the side member at the rear end, and this is used as a stay material. Is inserted into the hole of the bumper reinforcement and is expanded again by electromagnetic forming to be joined to the bumper reinforcement. In the present specification, regardless of the front side and the rear side of the vehicle, the collision surface side is the front and the opposite side is the rear.

  On the other hand, Patent Documents 2 and 3 describe that heat-treated aluminum alloy extruded material is expanded by electromagnetic forming in the state of a T1 treated material after press quenching, and is subjected to aging treatment after tube expansion to obtain a grade T5. Has been. Patent Document 4 discloses that T1 material has good formability by electromagnetic forming but has relatively low conductivity, T5 material has relatively poor formability but good conductivity, and O material has formability and conductivity. Although it is good, the strength is low and the cost is high.

JP 2004-237818 A JP 2007-254833 A JP 2002-160032 A JP 2005-105327 A

  In the bumper structure manufacturing method disclosed in Patent Document 1, referring to the disclosures of Patent Documents 2 to 4, when both the bumper reinforcement and the stay material are made of heat-treatable aluminum alloy extruded material, pipe expansion by electromagnetic forming is performed. For the stay material to be subjected to tempering, it is advisable to improve the strength by electromagnetic forming in the T1 state with excellent formability and joining with bumper reinforcement, then aging treatment (T5) of the obtained bumper structure Conceivable. In this case, the bumper reinforcement is not substantially deformed by electromagnetic forming, but it must be in the T1 state at the time of electromagnetic forming in consideration of receiving an aging treatment after joining.

However, because the shape of the bumper structure is not simple, handling when charging into the aging furnace is not easy, and the efficiency of the aging treatment is poor (only a lot of space is accumulated when stacked in the furnace), and transportation There is a problem of poor efficiency. In addition, the bumper structure is required to have a flat front wall of the bumper reinforcement and a stay mounting flange that are parallel to each other in order not to reduce the energy absorption efficiency at the time of collision. When the correction is performed after the aging treatment, a large-scale device is required. Furthermore, when the bumper reinforcement and the stay material are different, for example, when the bumper reinforcement is made of JIS 7000 series aluminum alloy and the stay is made of JIS 6000 series aluminum alloy, the former aging treatment condition is about 130 ° C. × 12 hours, and the latter aging treatment condition is A temperature of about 190 ° C. × 3 hours is preferable, but there is also a problem that half-time aging treatment conditions such as 160 ° C. × 6 hours must be selected for aging treatment together.
In this specification, the stay material after joining to the bumper reinforcement by electromagnetic forming is referred to as stay.

  The present invention eliminates the above-mentioned problems associated with the aging treatment of the bumper structure when the bumper reinforcement and the stay material are joined using electromagnetic forming to manufacture the bumper structure, and the material of the bumper reinforcement and the stay The purpose is to enable appropriate aging treatments to be applied to both cases when they are different.

  In the bumper structure manufacturing method according to the present invention, a tubular heat-treated aluminum alloy extruded material cut into a predetermined size is expanded by electromagnetic forming at a grade T1, and is fixed to the front end of the side member at the rear end. A heat treatment mold in which a stay material having a flange is molded, the stay material is subjected to aging treatment to obtain a quality T5, and the stay material after the aging treatment has a hollow section and has front and rear vertical walls and a texture T5. The bumper reinforcement made of aluminum alloy is inserted into the holes formed in the front and rear vertical walls of the left and right ends of the bumper reinforcement from the rear side, and the portion located on the front side from the vicinity of the hole formed in the vertical wall behind the bumper reinforcement The pipe is expanded by electromagnetic forming, and is bonded to the bumper reinforcement while being in close contact with the inner peripheral surface of the hole formed in the front and rear vertical walls.

  In the present invention, a heat-treatable aluminum alloy profile having a solid cross section (non-hollow cross section) can also be used as the bumper reinforcement. In this case, the bumper structure manufacturing method according to the present invention expands a tubular heat-treated aluminum alloy extruded material cut to a predetermined size by electromagnetic forming at the grade T1, and is fixed to the front end of the side member at the rear end. A stay material having a mounting flange is molded, and the stay material is subjected to an aging treatment to obtain a quality T5. The stay material after the aging treatment is solid in cross section and has a single vertical wall, and the quality T5. The front end portion of the stay material including the vicinity of the hole formed in the vertical wall of the bumper reinforcement is inserted by electromagnetic forming into the hole formed in the vertical wall of the bumper reinforcement made of the heat treated aluminum alloy. The pipe is expanded and brought into close contact with the inner peripheral surface of the hole formed in the vertical wall and joined to the bumper reinforcement.

In the present invention, the heat-treatable aluminum alloy means JIS 2000 (Al—Cu—Mg), JIS 6000 (Al—Mg—Si— (Cu)), and JIS 7000 (which can be strengthened by aging treatment). Al-Zn-Mg- (Cu) -based) aluminum alloy. Further, T1 and T5 are categorized according to JISH0001, T1 means a state of being cooled after extrusion, and T5 means a state of being further subjected to artificial aging treatment.
In addition, as the bumper reinforcement, for example, a shape member (meaning a member having substantially the same cross-sectional shape in the length direction, including a member obtained by bending a plate material by bending, roll processing, etc. in addition to an extruded material) is preferable. However, it is also possible to use an aluminum alloy material (a molded product having a different cross-sectional shape in the length direction) other than the shape material.

In order to carry out the above manufacturing method, for example, the following specific forms can be taken.
(1) Before electromagnetically forming the stay material after the aging treatment, the portion of the stay material to be subjected to electromagnetic forming is locally heated (for a part in the length direction). In this case, the stay material after solution heating is expanded by electromagnetic forming and joined to the bumper reinforcement, and if necessary, the solution material heated portion of the stay material is locally reheated to precipitate hardening. Let
(2) Solution heating and reheating are performed by high frequency induction heating.
(3) The bumper reinforcement is made of a JIS 7000 series aluminum alloy, and the stay material is made of a JIS 6000 series aluminum alloy.
(4) The tubular heat treatment type aluminum alloy extruded material is expanded by electromagnetic forming at the grade T1 to form the stay material, and then the mounting flange is flattened by pressing.

In the present invention, the heat treatment type aluminum alloy extruded material of quality T1 is expanded by electromagnetic forming, a stay material having a mounting flange at the rear end is formed, and the stay material is subjected to aging treatment to obtain quality T5. On the other hand, the bumper reinforcement made of heat-treatable aluminum alloy is classified as grade T5, the stay material of grade T5 is inserted into the hole formed in the bumper reinforcement of grade T5, and the bumper reinforcement is expanded by electromagnetic forming. Join to reinforcements.
As described above, in the present invention, the stay material and the bumper reinforcement are subjected to aging treatment (quality grade T5) before joining, so that each part is easy to handle and can be charged closely into the furnace so that the aging treatment efficiency is high. The transportation efficiency is also good. In addition, since aging treatment is performed on individual parts, distortion is less likely to occur than when applied to a bumper structure after joining, and even if the material of the bumper reinforcement and stay material are different, different conditions Since the aging treatment can be performed with, the optimum aging treatment conditions for each part can be selected.

  In the present invention, the mounting flange that is electromagnetically molded with a relatively large tube expansion ratio (see Patent Document 2) is formed in a T1 state with good moldability, so that the mounting flange is formed around the molded mounting flange. Cracking is prevented from occurring. Electromagnetic forming for joining is performed in the T5 state, but the deformation amount (expansion rate) of the stay material at this time is relatively small, and it is still possible to ensure sufficient joining strength. Even in the T5 state, which cannot be relatively large, it is possible to expand the tube without causing cracks or the like.

  In the present invention, as shown in (1) above, when a part of the stay material after aging treatment (the part where the electromagnetic forming is subsequently performed) is locally solution-heated, the solution-heated part is softened. Formability is improved. The solution-heated portion includes a portion that participates in bonding with the bumper reinforcement. By improving the formability of this portion, bonding by electromagnetic forming is more reliably performed. After joining the stay material to the bumper reinforcement, when the solution-heated portion is reheated and precipitation hardened, the strength of the softened portion is improved again. This solution heating and reheating can be easily performed by high frequency induction heating, as shown in (2) above.

  By performing such solution heating and reheating as necessary, for example, in a bumper structure using a bumper reinforcement having a hollow cross section, the strength of the portion located on the front side from the vicinity of the rear wall of the stay bumper reinforcement is increased. It can also be adjusted. In the event of a collision, the bumper reinforcement (and the part located in the hollow section of the stay's bumper reinforcement) will preferentially collapse, and if the impact load is large, the part protruding backward from the bumper reinforcement of the stay will also collapse. However, it is desirable for the crushing to proceed in order from the front side. The protruding portion may be crushed first, and the bumper reinforcement may be crushed, resulting in a decrease in energy absorption efficiency, or damage to the sensors installed on the portion protruding backward from the stay bumper reinforcement. Conversely, if the strength of the stay located in the hollow cross section of the bumper reinforcement of the stay is too low, the bumper reinforcement will easily collapse during a collision, resulting in insufficient energy absorption, and even a small collision will protrude backward from the stay's bumper reinforcement. There is a possibility of proceeding to the crushing part. In the vicinity of the rear wall of the bumper reinforcement so that the collapse proceeds in order from the front side of the bumper structure according to the magnitude of the impact load at the time of collision by appropriately performing the solution heating and reheating as necessary. It is possible to adjust the strength of the portion located further forward. The above points are the same for the bumper structure using the bumper reinforcement having a solid cross section.

  In the present invention, when the stay material is expanded by electromagnetic forming and joined to the bumper reinforcement, only part of the length of the stay material is electromagnetically formed because it is not necessary to electromagnetically form the entire length of the stay material. It is. When an aluminum alloy material with a hollow cross section is used as the bumper reinforcement, at least the part of the stay material that is involved in joining, that is, the part that is located on the front side from the vicinity of the hole formed in the vertical wall behind the bumper reinforcement (up to the front end) ) Can be joined to the bumper reinforcement. When a solid aluminum alloy material is used as the bumper reinforcement, at least the part of the stay material that is involved in the joining, that is, at least the vertical wall of the bumper reinforcement. If the front end portion including the vicinity of the formed hole is electromagnetically formed, the stay material can be joined to the bumper reinforcement. By electromagnetically forming only a part of the length of the stay material in this way, the distortion generated in the bumper structure is reduced compared to the case where the stay material is electromagnetically formed over the entire length, and the mounting flange is also distorted. Can be prevented. Further, there is an advantage that the energy required for electromagnetic forming is small and the capacity of the electromagnetic forming coil and the power source can be reduced. Even when a tubular aluminum alloy extruded material is expanded by electromagnetic forming and a stay material having a mounting flange fixed to the front end of the side member at the rear end is formed, the extrudate is not electromagnetically formed over the entire length. However, by electromagnetically forming only a part of the length direction (only the necessary part), similarly, the energy for electromagnetic forming can be reduced, and the capacity of the electromagnetic forming coil and the power source can be reduced.

In the present invention, as shown in (3) above, when the bumper reinforcement is made of a JIS 7000 series aluminum alloy and the stay material is made of a JIS 6000 series aluminum alloy, the bumper reinforcement has higher strength and is thinner. It becomes possible, and a stay with a greater crushing deformation at the time of collision is less likely to crack. Thereby, the energy absorption amount of the bumper structure can be stably improved and the weight can be reduced.
In the present invention, as shown in the above (4), when the mounting flange for the stay material is formed, if the press work is used together, the mounting flange can be accurately formed as compared with the case of only the pipe expansion by electromagnetic forming. Since it is not necessary to expand the mounting flange at right angles to the axial direction by expanding the pipe by electromagnetic forming, electromagnetic forming can be performed with low energy, and the capacity of the electromagnetic forming coil and the power source can be reduced.

First, with reference to FIGS. 1-6, the example of the manufacturing method of the bumper structure which concerns on this invention is demonstrated concretely.
As shown in FIGS. 1 to 3, the target bumper structure includes a bumper reinforcement 1 having a hollow rectangular cross section and a stay 2 joined to the bumper reinforcement. The bumper reinforcement 1 is made of a T5 treated 7000 series aluminum alloy extruded material, and has a rectangular cross section consisting of a vertical wall 3 on the front side (impact surface side), a vertical wall 4 on the rear side (vehicle body side), an upper wall 5 and a lower wall 6. Thus, the central portion 1a in the vehicle width direction is parallel to the vehicle width direction, the both end portions 1b are bent and inclined rearward, and circular holes 7 and 8 are formed in the vertical wall 3 and the vertical wall 4 at the inclined ends. Is formed.

The stay 2 is made of a T5-treated extruded 6000 series aluminum alloy, and the shaft portion 9 facing in the longitudinal direction of the vehicle body has a substantially circular cross section, and is fixed to the front end of a side member (not shown) at the rear end of the shaft portion 9. A mounting flange 11 is formed perpendicular to the longitudinal direction of the vehicle body. The front portion of the shaft portion 9 (the portion involved in joining) is fitted into the hollow cross section of the bumper reinforcement 1 and is in close contact with the inner peripheral surface of the hole 7 of the vertical wall 3 and the hole 8 of the vertical wall 4. It protrudes in the outer diameter direction before and after 7 and 8 and is firmly joined to the bumper reinforcement 1.
2 and 3, reference numerals 12 to 15 are bolt holes formed in the mounting flange 11, and 16 to 19 are work holes for bolting.

The manufacturing procedure of this bumper structure will be described. First, as shown in FIG. 4, a 6000 series aluminum alloy extruded material having a circular cross section that has been heat-treated to grade T1 is cut, and the front end is inclined to the end of the bumper reinforcement 1. A first stay material 21 having a predetermined dimension that is inclined at the same angle and whose rear end is perpendicular to the axial direction is created, and is placed in a molding hole of a mold (split mold) 22. The electromagnetic forming coil 23 is inserted into the hollow interior, an instantaneous large current is passed through the electromagnetic forming coil 23, and the tube is expanded by electromagnetic forming.
This electromagnetic forming is substantially performed only on the rear portion of the first stay material 21, the portion of the first stay material 21 is expanded, and the portion located inside the molding hole of the mold 22 is the molding hole. The rear end portion which was molded into the shape along the inner peripheral surface of the mold and protruded to the outside of the molding hole was expanded to a shape along the end surface of the mold 22 (the lower surface of the mold 22 shown in FIG. 4). Molded. FIG. 5 shows the second stay material 24 formed by this electromagnetic forming.

As shown in FIG. 5, the molded second stay material 24 includes a relatively small-diameter cylindrical portion 24a, an inclined short truncated conical portion 24b, and a relatively large-diameter cylinder from the front side. It consists of the shape part 24c and the flange 11 for attachment of a rear end. The truncated conical portion 24b, the cylindrical portion 24c, and the mounting flange 11 are portions where the pipes are expanded by electromagnetic forming, and the cylindrical portion 24a is not substantially expanded.
When forming the second stay material 24, the electromagnetic forming does not form the shape shown by the solid line in FIG. 5 at the same time, but first forms the shape shown by the phantom line (the mounting flange 11 has a shallow spread angle θ), Subsequently, by pressing using a mold, the mounting flange 11 is vertically expanded and flattened (particularly, the rear surface serving as the mounting surface with respect to the front end of the side member) is formed in a two-step process. You can also.

Subsequently, the second stay material 24 is subjected to aging treatment and is classified as T5. The aging treatment conditions vary somewhat depending on the type of 6000 type aluminum alloy, but it is sufficient to select conditions that can increase the strength from the range of about 160 to 220 ° C. × 2 to 10 hours. This condition itself is well known.
On the other hand, bumper reinforcement 1 is also subjected to aging treatment and is classified as T5. The aging treatment conditions here vary somewhat depending on the type of the 7000 series aluminum alloy, but it is sufficient to select conditions that can increase the strength from the range of about 100 to 150 ° C. × 10 to 15 hours. This condition itself is well known.

The bumper reinforcement 1 and the second stay material 24, which are classified as T5, are arranged as shown in FIG. By this time, bolt holes 12 to 15 are formed in the mounting flange 11 of the stay material 24, and the holes 7 and 8 into which the stay material 24 is fitted in the longitudinal walls 3 and 4 at both ends of the bumper reinforcement 1, and Work holes 16 to 19 are formed in the vicinity.
As shown in FIG. 6, the cylindrical portion 24 a of the second stay material 24 is fitted into the holes 7 and 8 of the bumper reinforcement 1 from the rear side (vertical wall 4 side), and the tip of the cylindrical portion 24 a is the bumper reinforcement 1. The front wall of the vertical wall 3 slightly protrudes forward, and the truncated conical portion 24 b is disposed at a position slightly rearward of the vertical wall 4. The vertical wall 3 (particularly the front surface) of the central portion 1a of the bumper reinforcement 1 and the mounting flange 11 (particularly the rear surface) of the second stay material 24 are parallel to each other, and the axial direction of the second stay material 24 is the bumper reinforcement. 1 is perpendicular to the vertical wall 3 (particularly the front surface) of the central portion 1a, and the bolt holes 12 to 15 are at predetermined positions on the left and right.

In this arrangement state, the electromagnetic forming coil 25 is inserted into the hollow interior of the stay material 24, an instantaneous large current is passed through the electromagnetic forming coil 25, and tube expansion is performed by electromagnetic forming.
By this electromagnetic forming, the portion of the second stay material 24 located on the front side from the vicinity of the vertical wall 4 of the bumper reinforcement 1 (specifically, the front portion from the position slightly on the rear side of the vertical wall 4 and the cylindrical portion) 24a and frustoconical portion 24b) (see FIG. 2), and adheres closely to the inner peripheral surface of the holes 7 and 8 formed in the vertical walls 3 and 4 before and after the bumper reinforcement 1, The part is freely deformed (the part protruding forward from the vertical wall 3 expands in the outer radial direction, the space between the vertical wall 3 and the vertical wall 4 projects in the outer radial direction, and the rear side of the vertical wall 4 also extends in the outer radial direction. The second stay material 24 is bonded to the bumper reinforcement 1.

  In this second electromagnetic forming, the second stay material 24 has a grade T5 and is stronger and has a lower formability than the grade T1, but the holes 7 and 8 of the bumper reinforcement 1 and the second stay material 24 The difference in diameter between the cylindrical portions 24a of the 24 can be set to be very small, and it is not necessary to increase the overhang before and after the holes 7 and 8, so that a high tube expansion rate is not required, and the connection with the bumper reinforcement 1 is hindered. It is done firmly.

  On the other hand, if necessary, the part expanded by the second electromagnetic forming of the stay material 24, that is, the part located on the front side from the vicinity of the vertical wall 4 of the bumper reinforcement 1 is locally solution-heated, and the part is heated. It can also be softened to improve moldability. For example, high-frequency induction heating is convenient for the solution heating, and as shown by the phantom line in FIG. 5B, the high-frequency induction heating coil 26 is mainly provided around the cylindrical portion 24a of the stay material 24 having the grade T5. The high-frequency current is applied while the coil is cooled with water, and the portion of the stay material 24 is induction-heated. As a heating condition, for example, a condition of 450 to 550 ° C. × 5 to 20 seconds can be mentioned. The part to be solution-heated may be a part in the axial direction, not the entire length in the axial direction of the part expanded by the second electromagnetic forming.

  When such solution heating is performed, after the second electromagnetic forming of the stay material 24 (after joining with the bumper reinforcement 1), the solution heated portion of the stay 2 of the bumper structure is locally reheated. The strength of the stay 2 can be increased (or the strength can be adjusted) by precipitation hardening. High-frequency induction heating is also convenient for this reheating, and as shown by the phantom line in FIG. 1, a high-frequency induction heating coil 27 is mainly disposed inside the stay 2 in the cross section of the bumper reinforcement 1, and the coil is cooled with water. A high frequency current is applied, and the portion of the stay 2 is induction heated. Examples of the heating conditions include 160 to 200 ° C. × 10 to 30 seconds. In addition, the part to reheat may be a part of axial direction instead of the whole axial direction of the part solution-heated.

Next, with reference to FIGS. 7-9, the other example of the manufacturing method of the bumper structure which concerns on this invention is demonstrated.
As shown in FIG. 7, the target bumper structure includes a bumper reinforcement 31 having a solid cross section and a stay 32 joined to the bumper reinforcement. The bumper reinforcement 31 is made of a T5 treated 7000 series aluminum alloy extruded material. As shown in FIG. 8, the bumper reinforcement 31 has a substantially U-shaped cross section including a vertical wall 33, an upper wall 34, and a lower wall 35. It is located near the front end as a surface. Similarly to the bumper reinforcement 1 shown in FIG. 1, the bumper reinforcement 31 also has a central portion in the vehicle width direction that is parallel to the vehicle width direction, and both end portions are bent rearward to be inclined, and the vertical wall 33 at the inclined end portion. A circular burring hole 36 protruding rearward is formed.

  The stay 32 is made of a T5-treated extruded 6000 series aluminum alloy, and a shaft portion 37 facing in the longitudinal direction of the vehicle body has a substantially circular cross section, and is fixed to the front end of a side member (not shown) at the rear end of the shaft portion 37. A mounting flange 38 is formed perpendicular to the longitudinal direction of the vehicle body. The front end portion of the shaft portion 37 (portion involved in joining) is in close contact with the inner peripheral surface of the burring hole 36 formed in the vertical wall 33 of the bumper reinforcement 31, and the front end is in the outer diameter direction along the curve of the burring hole 36. In addition to expanding to the rear, it projects in the outer diameter direction behind the burring hole 36 and is firmly joined to the bumper reinforcement 31.

  Explaining the manufacturing procedure of this bumper structure, the same procedure as described with reference to FIG. 4 is used to cut the 6000 series aluminum alloy extruded material having a circular cross section that has been heat-treated to the grade T1 to produce the first stay material. Then, the first stay material is expanded by electromagnetic forming. This electromagnetic forming is performed substantially only on the rear portion (portion excluding the front end portion) of the first stay material, and as shown in FIG. 9, from the front side, a relatively small-diameter cylindrical portion 39a (substantially The second stay material 39 is formed of an inclined short truncated conical portion 39b, a tubular portion 39c projecting to a relatively large diameter, and a mounting flange 38 at the rear end. The The second stay material 39 can also be formed by two stages of electromagnetic forming and press working of the mounting flange 38.

Subsequently, the second stay material 39 is subjected to aging treatment under the above-described conditions and is classified as T5. On the other hand, the bumper reinforcement 31 is also subjected to the aging process under the above-described conditions and is classified as quality T5.
The bumper reinforcement 31 and the second stay material 39, which are classified as T5, are arranged as shown in FIG. 9 in order to join them together. By this time, similarly to the second stay material 24 described above, bolt holes are formed in the mounting flange 38 of the second stay material 39, and both end portions of the bumper reinforcement 31 are formed as in the bumper reinforcement 1. A burring hole 36 into which the cylindrical portion 39a of the stay material 39 is fitted is formed in the vertical wall 33, and a work hole is formed in the vicinity thereof.

  As shown in FIG. 9, the cylindrical portion 39 a of the second stay material 39 is fitted into the hole 36 of the bumper reinforcement 31 from the rear side, and the tip of the cylindrical portion 39 a is forward from the front surface of the vertical wall 33 of the bumper reinforcement 31. It protrudes slightly, and the truncated conical portion 39 b is arranged at a position slightly rearward from the vertical wall 33. The vertical wall 33 (especially the front surface thereof) located in the vehicle width direction central portion (see 1a in FIG. 1) of the bumper reinforcement 31 and the mounting flange 38 (especially the rear surface) of the second stay material 39 are parallel to each other. The axial direction of the second stay material 39 is perpendicular to the vertical wall 33 (particularly the front surface thereof) located in the vehicle width direction center portion (see 1a in FIG. 1) of the bumper reinforcement 31.

  In this arrangement, the front end portion of the second stay material 39 including the vicinity of the burring hole 36 (specifically, the front portion from a position slightly behind the burring hole 36, and the cylindrical portion 39a and the truncated conical portion 39b). Is expanded by electromagnetic forming. As a result, as shown in FIG. 7, the second stay material 39 is in close contact with the inner peripheral surface of the burring hole 36, expands in the outer diameter direction along the curve of the burring hole 36, and the front end is the burring hole 36. Slightly protruding forward and projecting in the outer diameter direction behind the burring hole 36, and thereby joined to the bumper reinforcement 31. In the second electromagnetic forming, a high tube expansion rate is not necessary for the same reason as described above for the second stay material 24.

  Also in the stay material 39, the part that is expanded in the second electromagnetic forming, that is, the front end portion of the stay material 39 is locally solution-heated to improve the formability. Also, when solution heat is applied, after the second electromagnetic forming of the stay material 39, the solution heat-heated portion is locally reheated to cause precipitation hardening, and the strength of the stay 32 is increased (or strength adjustment). Can be achieved.

It is a top view of the bumper structure concerning the present invention. It is a partial cross section top view of the principal part (stay vicinity) of the bumper structure. It is a front view (figure seen from the front) of the principal part (stay vicinity) of the bumper structure. It is a figure explaining the first electromagnetic forming among the manufacturing methods of the bumper structure. It is the top view (a) and side view (b) of the stay raw material shape | molded by the 1st electromagnetic forming among the manufacturing methods of the bumper structure. It is a figure explaining the 2nd electromagnetic forming among the manufacturing methods of the bumper structure. It is a partial cross section top view of the principal part (stay vicinity) of another bumper structure based on this invention. It is sectional drawing in the burring hole of bumper reinforcement used for the bumper structure. It is a figure explaining the 2nd electromagnetic forming among the manufacturing methods of the bumper structure.

Explanation of symbols

1,31 Bumper reinforcement 2,32 Stay 3 Vertical wall on the front side of the bumper reinforcement 4 Vertical wall on the rear side of the bumper reinforcement 7,8 holes 11,38 Mounting flange 21 First stay material 22 Mold 23,25 Electromagnetic forming Coil 24 Second stay material 26, 27 High frequency induction heating coil 33 Bumper reinforcement vertical wall

Claims (11)

The heat treatment type aluminum alloy extruded material cut into a predetermined size is expanded by electromagnetic forming at the grade T1, and a stay material having a mounting flange fixed to the front end of the side member at the rear end is formed. The aging treatment is made into a grade T5, and the stay material after the aging treatment is made of a heat-treatable aluminum alloy made of heat-treated aluminum alloy having a hollow cross section and front and rear vertical walls, and the right and left ends of the bumper reinforcement. Fit into the holes formed in the front and rear vertical walls from the rear side, expand the portion located on the front side from the vicinity of the hole formed in the rear vertical wall of the bumper reinforcement by electromagnetic forming, to the front and rear vertical walls A bumper structure manufacturing method, wherein the bumper reinforcement is bonded to an inner peripheral surface of a formed hole and bonded to the bumper reinforcement. The method for manufacturing a bumper structure according to claim 1, wherein a portion of the stay material to be subjected to electromagnetic forming is solution-heated locally before electromagnetic forming of the stay material after aging treatment. The portion of the stay material to be solution-heated is a portion located on the front side from the vicinity of the hole formed in the rear vertical wall when fitted into the hole of the bumper reinforcement. The manufacturing method of the bumper structure described in 1 above. The heat treatment type aluminum alloy extruded material cut into a predetermined dimension is expanded by electromagnetic forming at the grade T1, and a stay material having a mounting flange fixed to the front end of the side member at the rear end is formed. The stay material after the aging treatment is applied to the vertical wall of the bumper reinforcement made of heat-treatable aluminum alloy having a solid cross section and a single vertical wall and tempered T5. An inner peripheral surface of the hole formed in the vertical wall by fitting the front end portion of the stay material including the vicinity of the hole formed in the vertical wall of the bumper reinforcement by electromagnetic forming into the formed hole from the rear side. A bumper structure manufacturing method, wherein the bumper structure is bonded to the bumper reinforcement. 5. The method for manufacturing a bumper structure according to claim 4, wherein, before electromagnetic forming of the stay material after aging treatment, a portion of the stay material to be subjected to electromagnetic forming is locally solution-heated. The stay material after solution heating is expanded by electromagnetic forming and joined to the bumper reinforcement, and then the solution heated portion of the stay material is locally reheated to cause precipitation hardening. The manufacturing method of the bumper structure described in any one of 2,3,5. 6. The method for manufacturing a bumper structure according to claim 2, wherein the solution heating is performed by high frequency induction heating. The method for manufacturing a bumper structure according to claim 6, wherein the reheating is performed by high frequency induction heating. The method for producing a bumper structure according to any one of claims 1 to 8, wherein the bumper reinforcement is made of an aluminum alloy extruded material. The method for manufacturing a bumper structure according to any one of claims 1 to 9, wherein the bumper reinforcement is made of a JIS 7000 series aluminum alloy, and the stay material is made of a JIS 6000 series aluminum alloy. 11. The tubular heat-treatable aluminum alloy extruded material is expanded by electromagnetic forming at a grade T1, and the stay material is formed, and then the mounting flange is flattened by pressing. A method for producing a bumper structure described in any one of the above.

Images