JP3403762B2 - Method for manufacturing tubular member for vehicle body structure - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tubular structural member constituting a vehicle body of an automobile, and more particularly to a tubular member having a rectangular cross section which is curved in a three-dimensional direction. The present invention relates to a method for manufacturing a shaped member. 2. Description of the Related Art Conventionally, automobile bodies have been manufactured by combining members having various shapes obtained by press-forming steel plates by spot welding or the like. In order to reduce the weight of steel, studies are being made to use aluminum instead of steel. For example, a front side frame member extending rearward from a lower portion of the engine room in front of the vehicle body and connected to a structural member of the passenger compartment front floor, a rear side frame member extending rearward from a structural member of the passenger compartment rear floor and reaching the lower portion of the trunk room, etc. Since it is a cylindrical member with a rectangular cross section that is almost constant over its entire length in the longitudinal direction, it has been a candidate for a target part for weight reduction of a vehicle body as a member that can be efficiently formed from an extruded aluminum square tube. Has been raised. [0003] However, as shown in FIG. 1, the front right side frame member 10 R on the front right side of the vehicle body will be described among a pair of front side frame members 10 R and 10 L of the vehicle 1. The front end portion 10c and the rear end portion 10a are linear, but a portion 10 connecting these linear portions 10c and 10a is formed.
The b is three-dimensionally bent downward and outward while extending rearward to avoid hitting the front wheel 2.
The front side frame member 10R is integrally provided with a vertically extending flange 10d for connection with a panel member such as a front wheel apron. Similarly, of the pair of rear side frame members of the vehicle 1, the front end portion 20c and the rear end portion 20a of the rear side frame member 20 on the rear right side of the vehicle body shown in FIG. The portion 20b connecting the portions 20c and 20a is three-dimensionally bent upward and inwardly of the vehicle body while extending rearward in order to avoid contact with the rear wheel 3. Further, a pair of horizontally extending flanges 20d and 20e are integrally erected for connection with a trunk floor or the like, and a portion 20 near the rear wheel 3 of the flange 20d.
f is configured to extend vertically upward for connection with the rear wheel apron. Accordingly, the front side frame member 10R and the rear side frame member 20
The most efficient method for forming the aluminum pipe by using an aluminum material is to bend an aluminum square pipe extruded into a rectangular cross section having a flange by press working or the like. However, aluminum square pipes have low strength and rigidity unlike steel square pipes, so simply bending them will cause defects such as wrinkles and cracks on the wall of the square pipe, and large deformation of the flange Resulting in. This is unsuitable as a method of manufacturing a vehicle body structural member that requires strength and shape accuracy for welding to a panel member of a vehicle body, and improvement has been strongly desired as compared with the related art. Accordingly, the present invention has been made in view of the above-mentioned situation, and has the following problems, such as the aforementioned front side frame member and rear side frame member.
An object of the present invention is to provide a method for manufacturing a tubular member for a vehicle body structure having a rectangular cross section that is curved in a dimensional direction without causing problems such as wrinkles and cracks on a wall surface due to bending and deformation of a flange. . SUMMARY OF THE INVENTION The object of the present invention is to provide a cylindrical member having a substantially annular cross section according to the present invention on its outer surface.
Has a flange that stands upright and extends radially outward
Was extruded into so that bending giving the process curving the tubular member, and then bent walls of the tubular member
Surface to change its cross-sectional shape from a substantially annular shape to a substantially rectangular shape.
At the same time as forming, bend the flange in a predetermined direction
That was subjected to press working, the tubular member loaded with pressure in the interior of the tubular member while retained within the mold, together with the brought into close contact with the mold by overhang the walls, the
The flange is pressed and clamped by the mold to correct the bending deformation.
A cross-sectional shape of the tubular member is deformed into a rectangular shape by performing a correct overhanging process, thereby achieving a method for manufacturing a tubular member for a vehicle body structure. In the method of manufacturing a tubular member for a vehicle body structure according to the present invention, when the tubular member is bent, the sectional shape of the tubular member is substantially annular, and the tubular member is formed in any direction. Have almost the same bending rigidity, so that the bending direction can be set to any direction. In addition, since the wall surface is formed as a curved surface and has high surface rigidity, wrinkles and cracks are not easily generated on the wall surface even when bending is performed. Furthermore, since the bent cylindrical member having a substantially annular cross section is brought into close contact with a mold by overhanging and deformed into a rectangular cross section, a cylindrical member having a rectangular cross section with high shape accuracy can be obtained. In addition, by deforming the bent cylindrical member into a substantially rectangular shape by pressing, and then performing the overhang, the cross-sectional shape of the tubular member can be changed from a substantially annular shape to a rectangular shape only by the overhang processing. Even when molding is difficult, it can be easily formed into a rectangular cross section. Furthermore, the flange formed integrally with the cylindrical member is bent in a predetermined direction in the pressing process, and further, in the overhanging process, the flange is pressed and clamped by a mold to correct the bending deformation, so that the flange is moved in the predetermined direction. It can be shaped to extend. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a tubular member for a vehicle body structure according to the present invention will be described.
Examples applied to the front side frame member and the rear side frame member will be described in detail below with reference to the drawings. Embodiment 1 First, a method of manufacturing the front side frame member will be described. As shown in FIG. 1, the front side frame members 10 are provided in a pair symmetrically with respect to the center line of the vehicle body of the vehicle 1. Here, a front side frame member 10R provided on the front right side of the vehicle body is described. explain. The side frame member 10R includes cylindrical portions 10a, 10b, and 10c having a rectangular cross section extending vertically in the vertical direction, and a flange 10d extending vertically upward along the outer wall surface of the cylindrical portion of the vehicle body. are doing. The portions 10a and 10c at both ends of the cylindrical portion are linear, and extend in the front-rear direction of the vehicle body in parallel with each other. And
Curved cylindrical portion 1 connecting both end portions 10a and 10c
0b is curved in a three-dimensional direction downward and outward of the vehicle body from the front to the rear of the vehicle body.
The radius of curvature of the curve is small in the vertical direction and large in the horizontal direction. Next, the manufacturing of the front side frame member 10R will be described in the order of each step with reference to FIG. First, the first step shown in FIG. 2A is a step of extruding and forming a cylindrical member 11 made of an aluminum material, and the cylindrical member 11 has a cylindrical portion having a circular cross section with a constant thickness. It is extruded to have a constant thickness flange 11d, which is integrally formed on the outer surface thereof and extends radially outward.
In the first embodiment, the cross-sectional shape of the cylindrical portion 11a is a circular ring having a constant thickness, and the flange 11d is also extended outward in the radial direction. Then, the thickness may be changed depending on the portion, the cross-sectional shape may be, for example, an elliptical ring, or the flange 11d may be inclined with respect to the radial direction. The second step shown in FIG. 2B is a step of bending the straight cylindrical member 11 extruded in the first step into a vertical plane. This bending process is shown in FIG.
And a bending device 30 as shown in FIG. 4 is used to perform bending while applying a tensile force to the extruded cylindrical member 11, and one end of the cylindrical member 11 has a semicircular shape. The clamping type lower half 32 fixed to the wheel-shaped rotary bending die 31 provided with the groove 31a and the clamping type upper half 33 are fixed to the rotary bending die 31. The cylindrical member 11 extends in the horizontal direction, and its flange 11d is gripped by a movable holding die 34 that moves from the left side to the right side in the drawing during the bending. Furthermore, the cylindrical portion 11 of the cylindrical member 11
A core (not shown) is inserted through
In the bending in the process, the sectional shape is prevented from being deformed. Then, in this state, the rotary bending die 31 is slowly rotated clockwise around its center C so that the cylindrical member 11 matches the radius of curvature of the center of the semicircular groove 31a of the rotary bending die 31. To be bent upward in the vertical plane. Also, the bent portion of the tubular member 11 that is made to project downward in the vertical plane is bent using the same device as described above. As a result, the cylindrical member 11 extending linearly has linear portions 12a at both ends.
12c and a curved portion 12b connecting these straight portions 12a and 12c, is formed into a substantially S-shaped tubular member 12 in side view. In the present embodiment, the cylindrical member 11 is bent by the pull bending using the rotary bending die. However, the present invention is not limited to this, and the bending may be performed by using any other bending method. It is good to do. In the third step shown in FIG. 2C, the wall surface of the cylindrical member 12 bent in the second step is pressed vertically and horizontally by using a mold. The cross-sectional shape is changed from an annular shape to a substantially rectangular shape to form a cylindrical member 1.
3 is a pressing step. In the third step, press molding is performed using a mold that is formed in accordance with the curved shape of the cylindrical member 12 that has been bent in the second step. As shown in FIG. 5, the mold 40 includes a fixed mold 41 that holds the tubular member 12, a movable mold 42 that is displaced vertically downward, and a displaceable horizontal direction from right to left in the drawing. And a moving mold 43.
Then, the cylindrical portions 12a, 12b, and 12c having the annular cross section of the cylindrical member 12 are pressed and deformed in the vertical direction and the horizontal direction by the mold 40, and the curved wall surface as shown in FIG. Is formed into a cylindrical member 13 having a substantially rectangular cross-sectional shape. At the same time, the cylindrical member 12
Of the flange 1d is bent by being pinched and pressed by the molds 42 and 43, and the flange 1d extending upward in the vertical direction.
3d. The fourth step shown in FIG. 2D is an overhanging step of deforming the cross-sectional shape of the cylindrical member 13 having a substantially rectangular cross section in the third step into a rectangular shape. In Example 1, at the same time as the overhanging process, the second bending process for gently bending the tubular member 13 in the horizontal direction is performed at the same time. First, the second bending process in the fourth step is press forming performed by using a mold 50 whose cross section is shown in FIG. 6, and the cylindrical shape whose cross section is deformed to be substantially rectangular in the third step. This is performed by pressing the member 13 with the fixed mold 51 and the movable molds 52 and 53. At this time, hydraulic pressure is applied to the inside of the tubular member 13 to prevent deformation of the cross-sectional shape, and in addition, the tubular member 1
Since the wall surface of the cylindrical member 3 is curved and has a high rigidity, no wrinkles or cracks are generated on the wall surface even if the second bending process for gently bending the cylindrical member 3 is performed. . In addition, since the cylindrical member 13 is molded using the mold 50, the straightening process for improving the accuracy of the curved shape is performed at the same time. Furthermore, since the flange 13d of the cylindrical member 13 is pressed and formed by sandwiching and pressing the movable molds 52 and 53, the shape accuracy of the flange 14d can be improved. When the second bending process is completed when the respective dies of the dies 50 come into close contact with each other, the pressure of the hydraulic pressure applied to the inside of the tubular member 13 is further increased to thereby increase the pressure. An overhanging process is performed in which the wall surface is expanded so as to be in close contact with the inner surface of the mold 50 and the cross-sectional shape thereof is changed from a substantially rectangular shape to a rectangular shape. Thereby, the cylindrical member 13 is formed into a cylindrical member 14 having a rectangular cross section shown in FIG. 2D, and if both ends are cut to a predetermined length, the front side frame member 10R can be formed. Complete. Also, the front side frame member 10 symmetrical to the front side frame member 10R
L can also be manufactured by exactly the same manufacturing method. That is, in the first embodiment, since the flange is extruded and formed integrally with the cylindrical member having the annular cross section in the first step, the productivity can be improved, and the manufacturing method for attaching the flange by welding can be achieved. In comparison with the above, the problem of strength reduction due to welding does not occur.
Further, in the second step, the cylindrical member having an annular cross section having high rigidity and strength of the wall surface is bent while being pulled, so that no wrinkles or cracks are generated on the wall surface of the cylindrical member. further,
In the third step, by performing a pressing process for deforming the cross-sectional shape of the cylindrical member from an annular shape to a substantially rectangular shape, the overhanging process in the fourth process is facilitated,
Since the bending of the flange is performed, the cylindrical member can be efficiently formed. In addition, in the fourth step, while applying pressure to the inside of the tubular member,
By performing press forming using a mold, the second bending process and the overhanging process of changing the cross-sectional shape from a substantially rectangular shape to a rectangular shape are performed continuously, so that it is possible to efficiently perform the forming, By performing the second bending in the fourth step, it is possible to simultaneously correct the curvature of the tubular member. In the first embodiment, the bending of the front side frame member in the vertical direction is performed in the second step, and the bending of the front side frame member in the horizontal direction is performed in the fourth step. You do not need to be caught in
According to the shape of the front side frame member, a bending process for bending in a three-dimensional direction is performed in the second step, and the fourth process is performed.
In the process, only the overhanging process and the straightening of the curvature may be performed. Further, in order to remove the influence of work hardening in the course of the working step, an appropriate annealing step may be added, or the annealing step may be combined with a solution quenching treatment. Further, the mold 40 used for the pressing process in the third step and the mold 50 used for the overhanging process in the fourth step of the first embodiment have flat surfaces in contact with the cylindrical members 13 and 14. However, there is no need to be limited to this, and by providing a protruding portion on the surface of the mold, a concave portion may be formed on the surfaces of the cylindrical members 13 and 14 and used for positioning. Second Embodiment Next, a description will be given of a second embodiment in which the method of manufacturing a tubular member for a vehicle body structure according to the present invention is applied to a rear side frame member. A pair of rear side frame members 20 are provided symmetrically with respect to the center line of the vehicle 1.
Here, the rear side frame member 20R on the rear right side of the vehicle body illustrated in FIG. 1 will be described. As shown in FIG. 1, the rear side frame member 20R is provided with a pair of flanges 20d and 20e with respect to the front side member 10R, and these flanges 20d and 20e extend in the horizontal direction, respectively. The difference is that only the portion adjacent to the rear wheel 3 of the flange 20d is bent so as to extend upward in the vertical direction. However, the method of manufacturing the rear side frame member 20R is almost the same as that of the front side member 10R described in the first embodiment.
Hereinafter, the description will be made in the order of each step, focusing on the different parts. First, in a first step shown in FIG. 7 (a), a cylindrical portion 21a having an annular cross section with a constant thickness is provided.
And a pair of flanges 2 integrally formed on the outer surface of the cylindrical portion 21a so as to extend radially outward.
The cylindrical member 21 made of aluminum and composed of 1d and 21e is extruded. The angle between the flanges 21d and 21e is about 90 degrees in the second embodiment. In the second step shown in FIG. 7B, the linear cylindrical member 2 extruded and formed in the first step by using the bending apparatus 30 as described in the first embodiment.
1 are curved in a vertical plane to form straight sections 22 parallel to each other.
a and 22c and a curved member 22b connecting these straight portions 22a and 22c. In the third step shown in FIG. 7C, the wall surface of the cylindrical member 22 that has been bent in the second step is pressed vertically and horizontally by press molding using a mold. By doing so, the cross-sectional shape is changed from an annular shape to a substantially rectangular shape, and at the same time, the pair of flanges 22 d
Bending is performed so that 22e extend in the horizontal direction at about 180 degrees from each other. At this time, as shown in FIG.
The 22e is nipped and pressed by the movable mold 62, the fixed mold 61, and the movable mold 63, and is bent so as to extend in the horizontal direction. On the other hand, as shown in FIG. The portion 22f adjacent to the ring 3 is formed so as to extend vertically upward. In the fourth step, similarly to the fourth step described in the first embodiment, a second bending process for gently bending the cylindrical member 23 in the horizontal direction and a substantially rectangular cross-sectional shape of the cylindrical member 3 are performed. And a bulging process for deforming the shape into a rectangle at the same time. That is, as described in the second embodiment,
In the method of manufacturing a tubular member for a vehicle body structure according to the present invention, the flange integrally formed with the tubular member is bent in an arbitrary direction when performing pressing, and the flange is formed when performing overhanging. Since the bending deformation is corrected, the production of the tubular member can be performed extremely efficiently. According to the method for manufacturing a tubular member for a vehicle body structure of the present invention, the tubular member extruded into a substantially annular cross section is bent, and the cross-sectional shape is reduced to a substantially rectangular shape by pressing. Since it was deformed into a shape and formed into a rectangular shape by overhanging, the following excellent effects could be obtained. That is, since the cylindrical member extruded to have a substantially annular cross section has high rigidity and strength of the wall surface, even when the bending process for bending the cylindrical member is performed, wrinkles and cracks are hardly generated on the wall surface. . Then, after performing the bending process, the pressing process and the overhanging process are performed using a mold, and the substantially annular cross-sectional shape is deformed into a rectangular shape. Can be obtained. In addition, by integrally molding the flange by extrusion molding, not only can productivity be increased, but also a decrease in strength that occurs when the flange is welded can be avoided. Further, when performing the above-described pressing and overhanging, the flange is bent so as to extend in an arbitrary direction, and the flange is attached to the metal.
An overhang that clamps the mold and corrects its bending deformation
Since the work is performed , bending deformation of the flange can be prevented. Therefore, according to the method of manufacturing a tubular member for a vehicle body structure of the present invention, even if the tubular structural member has a three-dimensionally curved rectangular cross section, such as a side frame member of an automobile body, the aluminum member Because it can be manufactured without defects such as wrinkles and cracks on the wall using
This can greatly contribute to reducing the weight of the vehicle body.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an automobile showing a mounting portion of a body structure tubular member manufactured by the method for manufacturing a body structure tubular member of the present invention. FIG. 2 is a perspective view showing a first embodiment of a method of manufacturing a tubular member for a vehicle body structure according to the present invention for each step. FIG. 3 is a side view of the bending machine used in the first step shown in FIG. FIG. 4 is a front view of the bending machine used in the first step shown in FIG. FIG. 5 is a sectional view illustrating a pressing step in a third step shown in FIG. 2; FIG. 6 is a cross-sectional view illustrating a second bending and overhanging process in a fourth process shown in FIG. 2; FIG. 7 is a perspective view showing a second embodiment of the method of manufacturing the vehicle body structural tubular member according to the present invention for each step. FIG. 8 is a cross-sectional view of a general cross-section for explaining pressing in a third step shown in FIG. 7; FIG. 9 is a cross-sectional view of a vertical flange portion for explaining pressing in a third step shown in FIG. 7; [Description of Signs] 1 Vehicle 10 Front sight {frame member 11} Cylindrical member 12 extruded and formed in the first step of the first embodiment Cylindrical member 13 bent in the second step of the first embodiment 13 Cylindrical member 14 pressed in three steps 14 Cylindrical member 20 bulged in the fourth step of Example 1 Rear side frame member 21 Cylindrical member 22 extruded in the first step of Example 2 Example 2 The cylindrical member 23 bent in the second step of the cylindrical member 23 The cylindrical member 24 pressed in the third step of the second embodiment The cylindrical member 30 bulged in the fourth step of the second embodiment 30 The bending apparatus 40 Pressing mold 50 of Example 1 Overhanging mold 60 of Example 1 Pressing mold 70 of Example 2 Overhanging mold of Example 2

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI B21D 26/02 B21D 26/02 C (72) Inventor Yoshiya Suzuki 85 Hiramatsu, Susono City, Shizuoka Prefecture Inside Mitsubishi Aluminum Corporation (72) Inventor Shigeyuki Nakagawa 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Nissan Motor Co., Ltd. (72) Inventor Kenji Kanamori 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Masanobu Nakamura Kanagawa Prefecture 2-15-15 Fukuura, Kanazawa-ku, Yokohama, within Tube Forming Co., Ltd. (72) Inventor Yasutoyo Oki 2--15-15, Fukuura, Kanazawa-ku, Yokohama-shi, Kanagawa Prefecture Within Tube Forming Co., Ltd. (56) References JP 61-219435 (JP, A) JP-A-6-226339 (JP, A) JP-A-6-313215 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B21D 53/88 B21D 53/86 B21D 3/14 B21D 7/025 B21D 26/02

Claims (1)

(57) The Claims 1. A tubular member having a substantially annular cross section, the
A flag that is integrally erected on the outer surface and extends radially outward.
Extruded so as to have a flange, subjected to a bending process to bend this cylindrical member, and then pressed the wall surface of the bent cylindrical member to change the cross-sectional shape from a substantially annular shape
At the same time as deforming into a rectangular shape,
Was subjected to a pressing process to bend in the direction, the tubular member loaded with pressure in the interior of the tubular member while retained within the mold, when brought into close contact with the said mold by overhang the wall
In both cases, the flange is crimped and clamped by the mold,
A cross-sectional shape of the tubular member is deformed into a rectangular shape by performing an overhanging process for correcting deformation, thereby manufacturing a tubular member for a vehicle body structure.