JPH10192965A - Manufacture of cylindrical member for vehicle body structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of cracks in a flange part to be worked while suppressing the increase of the man-hour as extremely as possible, and to execute the bending of small radius of curvature. SOLUTION: A manufacturing method of a cylindrical member for a vehicle body structure in which a flange 3 is integratedly provided on the outer side, and the flange is bent so as to be on the outer side, comprises a first process in which a straight cylindrical member 21 on the outer side of which the flange 3 is integratedly provided is extruded, and a second process in which the cylindrical member 21 is bent so that the flange 3 is on the outer side, and in the first process, the cylindrical member 21 is extruded to the shape where a part 3a of the flange to be bent is notched while the sectional shape of an extruded hole part of the flange 3 is changed by a movable die.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a tubular member for a vehicle body structure having a curved portion, and more particularly, to a method for manufacturing a tubular member having a large degree of curvature and having a bent portion. The present invention relates to a method for manufacturing a tubular member for a vehicle body structure that prevents the occurrence of cracks and cracks in a flange.

[0002]

2. Description of the Related Art Conventionally, a vehicle body is formed by subjecting a steel sheet to press forming or bending an extruded steel pipe to combine various shaped body members, and using spot welding or the like to combine the various body members. Although it is manufactured by joining and integrating members, in recent years, use of a light alloy such as an aluminum alloy or a titanium alloy instead of a steel plate has been studied in order to achieve a lighter vehicle body. For example, structural members such as a front side frame member extending rearward from a lower portion of an engine room in front of a vehicle body and connected to structural members on a front floor of a passenger compartment, and a rear side frame member extending rearward from a structural member on a rear floor of a passenger compartment and reaching a lower portion of a trunk room. Needs to be a cylindrical member having a substantially constant cross-sectional shape over the entire length in the longitudinal direction.

FIG. 5 is a perspective view showing a conventional linear tubular member subjected to bending. In FIG.
Is a long cylindrical member formed by extruding an aluminum material, and is integrally formed with a hollow cylindrical portion 2 having a rectangular cross section with a constant thickness and one side surface 2a outside the cylindrical portion 2 along the longitudinal direction. And a flange 3 having a constant thickness.

The cylindrical member 1 has a predetermined shape, for example, as shown in FIG.
In order to perform the bending process in which the flange 3 is outwardly protruded as shown in (1), the tubular member 1 is loaded between the upper and lower dies of the bending press so that the flange 3 is directed outward, and a gripper is provided. By sandwiching both ends of the tubular member 1 by using, for example, a core (not shown) is inserted into the tubular portion 2 so that the cross-sectional shape of the tubular member 1 is not deformed. Then, the upper die is slowly lowered while applying a tensile force in the longitudinal direction of the cylindrical member 1 by the gripping tool or the like, and the cylindrical portion 2 and the flange 3 are moved outward so that the flange 3 becomes outwardly convex. The portion 3a to be bent is curved. In this way, the cylindrical member 11 curved so that the flange 3 is on the outside is obtained.

[0005]

Incidentally, in the tubular member 11 formed in this manner, a tensile force is generated in the flange 3 outside the bend during the above-mentioned bending, and a portion 3a to be bent is formed. Is stretched in the longitudinal direction,
The flange 3 cannot withstand the tensile strength generated by the bending, and for example, as shown in FIG. 7, a crack 4 or a crack reaching the hollow portion due to the tensile stress occurs in the bent portion 3 a. There was a point. The reason for this is that, as the portion 3a of the flange 3 to be bent becomes more outward, the tensile stress becomes higher, and the material is stretched in accordance with this tensile stress. This is because the absence of the material serves as a breaking point.

Therefore, if the flange 3 is to be bent with a small radius of curvature, a crack 4 or a crack is likely to occur in the bent portion 3a.
It is only possible to reduce the degree of bending, and it is difficult to perform bending with a small radius of curvature on the flange 3.

[0007] The present invention has been made in view of the above circumstances, and while minimizing the increase in man-hours, there is no occurrence of cracks or cracks in the portion of the flange to be bent, and the curvature is reduced. An object of the present invention is to provide a method of manufacturing a tubular member for a vehicle body structure that can be bent with a small radius.

[0008]

According to a first aspect of the present invention, there is provided a method for manufacturing a tubular member for a vehicle body structure, wherein the cylindrical member has a substantially polygonal cross section, and a flange is integrally provided outside the cross section. Further, when manufacturing a cylindrical member for a vehicle body structure in which the flange is curved outward, the extruded hole having the outer shape of the cylindrical member and a portion of the extruded hole which forms the flange are retreated. Using an extruder having a movable die freely provided and a mandrel inserted into the extruded hole, the cross-section has a substantially polygonal shape, and a flange is integrally provided on the outside thereof. By extruding the straight cylindrical member, and changing the cross-sectional shape of the extruded hole of the flange with a movable die, a flange that does not form the flange at the portion of the flange to be bent is formed. A first step of extruding the cylindrical member having the notch formed therein, and a second step of bending the cylindrical member obtained in the first step at the flange notch so that the flange is on the outside. And characterized in that:

Here, the invention according to claim 2 is characterized in that the mandrel is formed in a tapered shape, and the flange notch is formed thick by moving the mandrel forward and backward. is there. Further, according to a third aspect of the present invention, a roll bending apparatus for performing the second step is disposed downstream of the extrusion molding apparatus for performing the first step according to the first or second aspect. A straight cylindrical member extruded from a forming device is continuously fed to a roll bend device and bent.

According to the invention described in any one of the first to third aspects, in the extrusion step of the first step, the cylindrical member is extruded in a shape in which a portion of the flange to be bent is cut out in advance. There is no need to cut out a part of the flange by cutting, fusing, or the like after extrusion molding. Therefore, it is possible to reduce the number of steps required for manufacturing the cylindrical member, and it is difficult for unnecessary effects such as adverse effects at the time of bending to remain in the notched portion, thereby improving the quality of bending. In addition, since a portion of the flange to be bent is cut out before bending, the flange is less likely to crack when bent, and the radius of curvature of the flange is reduced. Therefore, a cylindrical member having a smaller radius of curvature can be obtained.

By the way, in the cylindrical member obtained as described above, since a flange notch is formed in a portion where bending is performed, depending on a part to be used, the notch in the notch may be changed. The strength may be insufficient.
In this regard, according to the second aspect of the present invention, the mandrel formed in a tapered shape is advanced and retracted, and the flange notch is formed to have a large thickness, so that the strength at such a bent portion is obtained. Shortages are avoided. Furthermore, according to the third aspect of the present invention, since the extruded product is continuously bent by the roll bending device disposed downstream of the extrusion device, the final product can be easily operated without taking up space for the processing equipment. Can be obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a configuration diagram showing an outline of processing equipment used in an embodiment of a method for manufacturing a tubular member for a vehicle body structure according to the present invention, and FIG. 2 is used in the same equipment. FIGS. 3 and 4 are front views of the extrusion dies, and FIGS. 3 and 4 are perspective views showing the shape of the molded product in each step. As shown in FIG. 1, this processing equipment is schematically constituted by an extrusion molding device 50 and a roll bend device 60 arranged downstream thereof. Here, the extrusion molding device 50 processes the cylindrical member 21 having the shape shown in FIG.
Is to perform a bending process on the tubular member 21 coming out of the extrusion molding device 50 to obtain a tubular member 31 having a shape shown in FIG.

The extruder 50 includes a container 51.
, An extrusion die 52, a stem 53, a pressing plate 54,
A mandrel 55 disposed on the stem 53 side. The roll bending device 60 has a plurality of bending rolls 61 for restraining the outer diameter of the cylindrical member 21 as a processing material, and passes the cylindrical member 21 coming out of the extrusion molding device 50 between the bending rolls 61. This is done by bending.

The extrusion die 52 of the extrusion molding apparatus 50
Is composed of a fixed die 52A and a movable die 52B, as shown in FIG.
Extrusion molding hole 58 having a predetermined cross-sectional shape between mandrel 55
Is formed. The extruded hole 58 in this case is
Portion 58a that forms cylindrical portion 2 of cylindrical member 21 shown in FIG.
And a portion 58b forming the flange 3. In addition, the movable die 52B is provided with an extrusion hole 58.
Is inserted from the outside into a portion 58b forming the flange 3 of the direction of FIG.
Direction), and its position can be adjusted at any time during extrusion by a drive mechanism 59. Further, the mandrel 55 is formed in a tapered shape in which a portion looking into the extrusion hole 58 gradually decreases in diameter toward the distal end side.

Next, a method for manufacturing a tubular member using the extrusion molding apparatus having the above-described configuration will be described. First, as a first step of the processing, the tubular member 21 shown in FIG. That is, the heated molding material (billet) 56 is inserted into the container 51 of the extrusion molding apparatus 50 shown in FIG.
Is pressed toward the extrusion die 52 by the stem 53 and is extruded from the extrusion hole 58 (see FIG. 2), whereby the rod-shaped tubular member 21 having the cross-sectional shape of the extrusion hole 58 is obtained.

The cylindrical member 21 has a substantially polygonal cross section, and the flange 3 is integrally provided on the outside thereof. In addition, during the first step, extrusion is performed by adjusting the position of the movable die 52B shown in FIG. 2 while changing the cross-sectional dimension of the portion 58b of the extrusion hole 58 where the flange 3 is formed. As a result, a cylindrical member 21 in which the portion 3a of the flange 3 to be bent is cut out is obtained. Since the strength of the part where the flange 3 is notched may be reduced, the mandrel 55 is retracted during the extrusion of the part.
The wall thickness of the cylindrical portion 2 can be made thicker to suppress a decrease in strength. In this case, the increase in the wall thickness may be performed on the entire cylindrical portion 2 or only on the wall on the flange 3 side.

Next, as a second step, the extruded tubular member 21 is fed to a roll bend device 60 as it is, and the cylindrical member 21 obtained in the first process is separated from the flange 3 by the roll bend device 60. It is bent so as to be on the outside, and the cylindrical member 31 of FIG. 4 is obtained. Here, since the portion 3a of the flange 3 to be bent is cut out in advance, when the flange 3 is bent so that the flange 3 is on the outside, there is no possibility that the flange 3 is cracked or cracked due to tensile stress. In addition, the cylindrical member 21 can be bent with a small radius of curvature.

Therefore, according to this manufacturing method, the first
In the extrusion forming step of the process, the cylindrical member 21 is extruded in a shape in which the portion 3a of the flange 3 to be bent is cut out, so that after extrusion, a part of the flange 3 is cut or melted. There is no need to perform notch processing, and there is no increase in the number of steps. In addition, since notches are not formed by post-processing such as cutting and fusing, an effect that adversely affects bending is hardly left in the notched portion, and the quality of bending can be improved. Further, since the extruded product is continuously bent by the roll bending device 60 disposed downstream of the extruding device 50, it is possible to obtain the cylindrical member 31 which is the final product with good workability without taking up space for the processing equipment. And no hassle in setting up the bending process. Therefore, although there are two processing steps, the first and second processing steps, a consistent automatic operation is possible and the production efficiency can be improved. Furthermore, if the tapered mandrel 55 is advanced and retracted to form the thickened portion 3a where the flange 3 is cut off, insufficient strength is not generated in the portion 3a.

In the above embodiment, the case where the roll bending method is used as the bending means for performing the second step has been described. However, the present invention is not limited to this. Although there is a possibility that the automatic operation cannot be performed, the bending may be performed by other means. That is, the second step employs, for example, a rotary bending method (draw bending method), a press bending method (compression bending method), a tension bending method (stretch bending method), and the like, which are generally known as bending. can do. Here, the rotary pull bending method is a processing method in which a processing material is pressed against a rotary bending die with a clamping die, and the rotary bending die is rotated as it is, thereby bending the processing raw material into a shape along the radius of the rotary bending die. . The pressing bending method is a processing method in which a work material is pressed against a fixed bending die with a rotating pressing die and bent. Furthermore, the tension bending method
This is a processing method in which a bending die is pressed and bent while a tensile force is applied to a processing material.

[0020]

As described above, according to the manufacturing method of the present invention as set forth in any one of claims 1 to 3, the movable die is used to extrude the flange in the first step of extrusion molding. Since the cylindrical member is extruded in a shape in which a portion to be bent is cut out, it is not necessary to cut out or cut a part of the flange by cutting or fusing after the extrusion. Therefore, the total number of steps can be reduced because the post-processing of the notch can be omitted. In addition, unnecessary effects such as adverse effects at the time of bending are less likely to remain in the notched portions, so that the quality of bending can be improved. In addition, since the portion of the flange to be bent is cut out before bending, the flange is less likely to crack when bent, and the radius of curvature of the flange is reduced. Therefore, a cylindrical member having a smaller radius of curvature can be obtained.

In particular, according to the manufacturing method of the second aspect of the present invention, the tapered mandrel is advanced and retracted to form the flange notch into a large thickness, thereby performing such a bending process. According to the third aspect of the present invention, the extruded product is continuously bent by the roll bend device disposed downstream of the extruding device, so that the location of the processing equipment is not generated. Thus, a tubular member as a final product can be obtained with good workability without taking any steps. Therefore, the automatic operation can be performed consistently without any trouble such as the setup of the bending process, and the effect of improving the production efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an outline of a processing facility for performing a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a front view of an extrusion die used for performing a first step of the manufacturing method according to the embodiment of the present invention.

FIG. 3 is a perspective view showing a tubular member for a vehicle body structure to be bent in the embodiment of the present invention.

FIG. 4 is a perspective view showing a bent body member for a vehicle body structure according to the embodiment of the present invention.

FIG. 5 is a perspective view showing a conventional tubular member for vehicle body structure to be bent.

FIG. 6 is a perspective view showing a conventional bent tubular member for a vehicle body structure.

FIG. 7 is a perspective view showing an example of a defect of a conventional tubular member for vehicle body structure.

[Explanation of symbols]

 3 Flange 3a Part to be bent 21, 31 Cylindrical member 50 Extrusion molding device 52B Movable die 58 Extrusion molding hole 58b Part forming flange 60 Roll bend device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B62D 25/00 B62D 25/00 65/00 65/00 A

Claims (3)

[Claims] 1. A method for manufacturing a tubular member for a vehicle body structure having a substantially polygonal cross section, a flange integrally provided outside the cross section, and curved so that the flange is outside. An extrusion molding hole having the outer shape of the cylindrical member, a movable die provided to be able to advance and retreat at a portion of the extrusion molding hole forming the flange, and a mandrel inserted into the extrusion molding hole. Using an extrusion molding device having a cross section of the above-mentioned substantially polygonal shape, and extruding a linear cylindrical member having a flange integrally provided on the outside thereof, the extrusion molding hole portion of the flange is formed. By changing the cross-sectional shape by a movable die, a first member for extruding the cylindrical member having a flange cutout portion not forming the flange in a portion of the flange to be bent is formed.
And a second step of bending the tubular member obtained in the first step at the flange notch so that the flange is located outside. Method for manufacturing a shaped member. 2. The method according to claim 1, wherein the mandrel is formed in a tapered shape.
The method for manufacturing a tubular member for a vehicle body structure according to claim 1, wherein the flange notch is formed to be thick by moving the mandrel forward and backward. 3. A roll bend device for performing the second step is provided downstream of the extrusion device for performing the first step, and a linear cylindrical member extruded from the extrusion device is provided. 3. The method for manufacturing a tubular member for a vehicle body structure according to claim 1, wherein the sheet is continuously fed to a roll bend device and bent.