JP2004261856A - Method for manufacturing tubular member having mounting flange - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a bumper stay 21 in the end parts of a shaft part 22 of which mounting flanges 23, 24 having long holes 25, 26 for mounting are formed by a simple method. <P>SOLUTION: Circular holes 28, 29 penetrating through the tube wall are formed in the end parts of a tube stock 27 consisting of an aluminum alloy extruded material and the flanges 23, 24 are formed by expanding the end parts of the tube stock 27 including the parts of the holes by electromagnetic forming. Approximately elliptic holes 25, 26 spread in the peripheral direction are formed on the flanges 23, 24. The flanges are strengthened by work hardening action owing to deformation. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of manufacturing a tubular member having a mounting flange by forming a mounting flange having a mounting hole at an end of a pipe made of an extruded aluminum alloy.
[0002]
[Prior art]
When forming a hole through which a bolt or the like is inserted into a mounting flange for mounting to another member, it may be desirable to form the hole as an elongated hole from the viewpoint of dimensional tolerance of each member and assembling workability. For example, in Patent Document 1 below, a long hole is formed in a mounting flange welded and fixed to the tip of a side member.
[0003]
[Patent Document 1]
JP-A-11-208393 [0004]
In the above example, it is considered that drilling in the mounting flange is performed before being fixed to the tip of the side member, and in that case, drilling can be easily performed, but integrated from the end of the member from the beginning. There is a case where it is difficult to make a hole in a mounting flange formed in a special manner, particularly, a hole made by punching.
For example, FIG. 7 shows a bumper stay 1 made of an aluminum alloy extruded material (the extrusion direction is perpendicular to the paper surface). A flange 3 for fixing to a bumper reinforce (not shown) is formed on the left and right of the front end of a shaft 2, and A flange 4 for fixing to the tip of a side member (not shown) is formed on the left and right sides of the end, and a bolt insertion hole 5 is formed in each of the flanges 3 and 4. When the hole 5 is formed near the shaft portion 2 (when the distance w is small), the hole 5 cannot be formed by punching because the punching die cannot be arranged below the flange, and it is necessary to make a hole by drilling. There is. This is disadvantageous in terms of cost, and also has a problem that a long hole cannot be formed by a drill.
[0005]
Further, in recent years, as a bumper structure of a vehicle, for example, as described in Japanese Patent Application Laid-Open No. 2001-294106, a structure in which bumper stays are attached to inclined portions at both ends of a bumper reinforce is mainly used. . In this case, as shown in FIG. 8, the flange 13 of the bumper stay 11 made of an aluminum alloy extruded material (the extrusion direction is perpendicular to the paper surface) is inclined along the inclination of a bumper reinforce (not shown), and the hole 15 is 12 (in the case where the distance w is small), compared to the bumper stay 1 in which both the flanges 3 and 4 are formed in a plane perpendicular to the axial direction, a hole is formed by punching (a gap with the shaft portion 12). Drilling of the flange 13 on the side having an acute angle between them becomes even more difficult.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of such a problem of the related art, and a member having a mounting flange having a mounting hole including a long hole formed at an end of a shaft portion is provided by a simple method. It is intended to be able to be manufactured.
[0007]
[Means for Solving the Problems]
The method for manufacturing a member having a mounting flange according to the present invention includes forming a hole through a tube wall at an end of a tube made of an extruded aluminum alloy, and electromagnetically forming the end of the tube including the hole. And forming a flange by expanding the diameter. After the electromagnetic forming, a hole is formed in the flange, the width of which is wider in the circumferential direction than the original one. In addition, if a circular hole is formed first, when the flange is formed by electromagnetic forming, the hole is simultaneously expanded in the circumferential direction, and the flange is formed with a substantially elliptical hole that is expanded in the circumferential direction. You. Conversely, if an elliptical hole whose major axis is oriented in the axial direction is formed first, a circular hole can be formed in the flange.
This method can be suitably used for manufacturing bumper stays, instrument panel reinforcements, and the like.
[0008]
The electromagnetic forming used in the present invention is a method in which a large current of, for example, 20 kA or more is instantaneously passed through a coil to generate a strong magnetic field, and an eddy current and a magnetic field flowing through a molded object (conductor) placed therein. For example, JP-A-58-4601, JP-A-6-313226, JP-A-7-116675, JP-A-9-166111, and JP-A-10-314869. As described in JP-A-11-204434, JP-A-2000-86228, JP-A-2000-264246, and the like, it is a known technique itself. It is also described in the specification and drawings attached to Japanese Patent Application Nos. 2002-200386 and 2002-357820.
[0009]
As the aluminum alloy extruded material used in the present invention, an aluminum alloy extruded material having a circular or elliptical cross section (including a shape close thereto) is preferable. However, it is also possible to use a tubular aluminum alloy extruded material having a polygonal cross section such as a quadrangle, a pentagon, a hexagon, or another cross section. Aluminum alloys are good conductors of electricity and are suitable for electromagnetic forming. This aluminum alloy is, for example, a JIS 6000-based or 7000-based aluminum alloy. In consideration of easiness of forming, the refining is electromagnetically formed with T1 or O specified in JIS H0001, and aging treatment is performed as necessary after forming. Good.
[0010]
In the electromagnetic molding, the end of the extruded material is protruded by a predetermined length from the end surface of the mold surrounding the aluminum alloy extruded material, and the end is instantaneously expanded in diameter by electromagnetic molding and pressed against the end surface of the mold. I do. Thereby, the end of the extruded material (the portion protruding from the end of the mold) is formed on the flange. This flange is finished in a shape along the end face of the mold. Therefore, if the end face of the mold is a plane perpendicular to the axial direction of the extruded material, the end of the extruded material is formed in the axial direction of the extruded material. If a vertical flange is formed and the end surface of the mold is inclined or curved with respect to the surface perpendicular to the axial direction of the extruded material, the end of the shaft portion is perpendicular to the axial direction of the extruded material. A flange inclined or curved with respect to the surface is formed. The width of the flange extending to the outer periphery is determined by the length of the protrusion from the end face of the mold. The use of electromagnetic molding ensures that the flange is formed in a short period of time, and that the flange is strengthened by work hardening due to deformation.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the method for forming the mounting flange according to the present invention will be described more specifically with reference to FIGS. Disclosed herein is an example of a bumper stay in which mounting flanges are formed at both ends of a shaft.
FIG. 1A shows a tube material 27 used in this method, which is made of an extruded aluminum alloy having a circular cross section. The end surfaces of both ends of the tube material 27 are cut in a plane perpendicular to the axial direction, and circular holes 28 and 29 penetrating the tube wall are formed at the end portions at equal intervals in the circumferential direction by, for example, punching.
[0012]
The periphery of the tube material 27 is surrounded by the split molds 30 (30a to 30d) shown in FIGS. 1B and 2, and the front end and the rear end of the tube material 27 have a predetermined length, and the end face of the split mold 30 is provided. It protrudes from 31 and 32 (see the phantom line in FIG. 2B). The holes 28 and 29 need to be located at the protruding portions. The split mold 30 can be vertically split into four, and when combined, a through hole 33 having an inner diameter substantially equal to the outer diameter of the tube material 27 is formed. The end faces 31 and 32 of the split mold 30 are planes perpendicular to the axial direction of the through hole 33, and both function as molding surfaces during electromagnetic molding. The sizes (outer diameters) of the flanges 23 and 24 after the electromagnetic molding are determined by the lengths of the split molds 30 projecting from the end faces 31 and 32.
[0013]
Next, the electromagnetic molding coil body 34 is inserted into the tube material 27, and when an instantaneous large current is applied to the electromagnetic molding coil body 34 from a shock current generator (not shown), the tube material 27 The front end and the rear end of the tube material 27 projecting from the end faces 31 and 32 of the split mold 30 are pressed against the end faces 31 and 32, and the flanges 23 and 24 are formed at both ends. 21 is manufactured. At this time, the holes 28 and 29, which were originally circular, are tensilely deformed in the circumferential direction along with the diameter expansion, and substantially elliptical holes 25 and 26 whose widths are increased in the circumferential direction are formed on the flanges 23 and 24 as circles. They are formed at equal intervals along the circumferential direction. Note that the shaft portion 22 of the stay 21 is pressed against the inner surface of the through hole 33 of the split mold 30 and is formed into a shape along the inner surface shape. After the molding, the split mold 30 is opened and the stay 21 is taken out.
[0014]
Next, an example of a stay in which the flange for attachment to the bumper stay is inclined outward in the vehicle width direction will be described.
The tube material 47 shown in FIG. 3A is also made of an extruded aluminum alloy having a circular cross section, and the end surfaces of both ends of the tube material 47 are cut in a plane perpendicular to the axial direction. At the rear end, circular holes 49 penetrating the pipe wall are formed at equal intervals in the circumferential direction and at the same distance from the end face of the tube material 47 by, for example, punching, while the front end has the same circular hole. 48 are formed at equal intervals in the circumferential direction, and there are ones at a distance S1 from the end face of the tube material 47 (shown by 48a) and those at a position of S2 (shown by 48b).
The periphery of the tube material 47 is surrounded by the split molds 50 (50a to 50d) shown in FIGS. 3B and 4, and the front end and the rear end of the tube material 47 have a predetermined length, and the end face of the split mold 50 is provided. It protrudes from 51 and 52 (see the imaginary line in FIG. 3B). The split mold 50 can be vertically split into four, and when combined, a through hole 53 having an inner diameter substantially equal to the outer diameter of the tube material 47 is formed. The end face 52 of the split mold 50 is a plane perpendicular to the axial direction of the through hole 53, but the end face 53 is inclined to one side (inclined in a direction in which the outside in the vehicle width direction is retracted). The tube material 47 is set in the split mold 50 such that the hole 48a faces outward in the vehicle width direction and the hole 48b faces inward in the vehicle width direction.
[0015]
Next, the electromagnetic molding coil body 54 is inserted into the tube material 47, and when a large current is instantaneously applied thereto, the tube material 47 instantaneously expands in diameter and protrudes from the end surfaces 51, 52 of the split mold 50. The front end and the rear end of the tube material 47 are pressed against the end surfaces 51 and 52, and the bumper stay 41 having the flanges 43 and 44 formed at both ends is manufactured. The overhang width W1 of the flange 43 on the outer side in the vehicle width direction is larger than the inner overhang width W2. The holes 48 and 49, which were originally circular, are deformed in the circumferential direction with the increase in diameter, and substantially oval holes 45 and 46 whose widths are increased in the circumferential direction are formed on the flanges 43 and 44. You. Of the holes 45, the holes 45a located on the outer side 43a in the vehicle width direction on the flange 43 correspond to the original holes 48a, and the holes 45b located on the inner side 43b in the vehicle width direction on the flange 43 correspond to the original holes 48b. Corresponding.
[0016]
Next, an example of a stay in which a hole formed in the mounting flange is circular will be described.
FIG. 5A shows a tube material 67 used in this method, which is made of an extruded aluminum alloy having a circular cross section. This tube blank 67 differs from the tube blank 27 in that holes 68, 69 formed at both ends are elliptical with the major axis oriented in the axial direction of the tube blank 67.
As shown in FIGS. 5B and 6, when this tube material 67 is electromagnetically formed in exactly the same manner as the tube material 27, the diameter of both ends is increased to form flanges 63 and 64 at both ends of the bumper stay 61. The holes 68 and 69, which were initially elliptical, were tensile-deformed in the circumferential direction as the diameter was increased, and substantially circular holes 65 and 66 whose widths increased in the circumferential direction were formed on the flanges 63 and 64 in the circumferential direction. Are formed at regular intervals.
[0017]
As described above, the tubular member according to the present invention has been specifically described using the bumper stay as an example. However, the method according to the present invention is applicable to a side member (a mounting flange is formed at a tip) of a vehicle such as a passenger car or a truck or an instrument panel. The present invention can be suitably used for the production of reinforce (a mounting flange is formed at one or both ends) and other tubular members requiring a mounting flange.
The side member is also described in Patent Document 1 and JP-A-2001-294106. The bumper stay is attached to the tip (fixing the bumper reinforce via the bumper stay), or the bumper reinforce is fixed directly to the tip. The instrument panel reinforcement is also referred to as a steering support, a steering hanger beam, or a cross member between pillars (PP member), and is disposed in the vehicle width direction and both ends are fixed to left and right frames of the vehicle. It is a member that supports a duct, a steering column, and the like, and also has a role of securing a living space for an occupant against a side collision of the vehicle. For example, Japanese Patent Application Laid-Open Nos. 11-115550, 2001-63628, and JP-A-2001-71939, JP-A-2001-253368, and JP-A-2002-21440 disclose an aluminum alloy instrument panel reinforce.
[0018]
【The invention's effect】
According to the present invention, when manufacturing a member having a mounting flange at an end of a shaft portion, a hole is previously formed in an end of a tube material by punching or the like, and then the end is enlarged by electromagnetic forming. By forming the flange by pressing, the member can be easily manufactured. Also, if a circular hole is formed at the end of the tube material by punching, etc., after electromagnetic forming, the hole will be formed into a substantially elliptical shape that spreads in the circumferential direction, so it is also possible to form a long hole in the flange. This makes it easy to form a flange having the mounting hole near the shaft.
[Brief description of the drawings]
FIG. 1 is a front view (a) of a tube material used for manufacturing a bumper stay by using the present invention, and a cross-sectional view (b) showing a method of manufacturing a bumper stay.
FIG. 2 is a plan view showing the manufacturing method.
FIGS. 3A and 3B are a front view of a tube blank used for manufacturing a bumper stay using the present invention and a cross-sectional view illustrating a method of manufacturing a bumper stay.
FIG. 4 is a plan view showing the manufacturing method.
FIGS. 5A and 5B are a front view of a tube material used for manufacturing a bumper stay using the present invention, and a cross-sectional view illustrating a method of manufacturing a bumper stay.
FIG. 6 is a plan view showing the manufacturing method.
FIG. 7 is a front view (partial cross section) of a conventional bumper stay.
FIG. 8 is a front view (partial cross section) of a conventional bumper stay.
[Explanation of symbols]
21, 41, 61 Bumper stays 23, 43, 63 Mounting flanges 24, 44, 64 Mounting flanges 25, 45, 65 holes 26, 46, 66 holes 27, 47, 67 Tube materials 28, 48, 68 holes 29, 49,69 holes

Claims (5)

Attachment characterized by forming a hole through the tube wall at the end of a tube made of an aluminum alloy extruded material, and expanding the end of the tube including the hole by electromagnetic forming to form a flange. Of manufacturing a tubular member having a flange for use. At the end of the tube made of extruded aluminum alloy, a circular hole penetrating the tube wall is formed, and the end of the tube including the hole is expanded by electromagnetic forming to form a flange, and the flange is formed. A method of manufacturing a tubular member having a mounting flange, wherein a substantially elliptical hole extending in a circumferential direction is formed. A tubular member having a mounting flange formed by the method according to claim 1 or 2 at a pipe end of a pipe made of an extruded aluminum alloy. The tubular member according to claim 3, which is a bumper stay. The tubular member according to claim 3, which is a reinforcement for an instrument panel.

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