JP4297213B2 - Manufacturing method of tubular member with flange - Google Patents

Description

The present invention relates to a method of manufacturing a flanged tubular member having a mounting flange at a shaft end, and more specifically, a mounting flange formed by expanding an end peripheral wall of an aluminum tube in an outer diameter direction by electromagnetic forming or the like. The present invention relates to a method for manufacturing a flanged tubular member .

  For example, bumper reinforcement is provided as a reinforcing member inside a bumper installed at the front end (front) and rear end (rear) of an automobile body such as a passenger car or a truck. The bumper reinforcement is a hollow member having a front wall and a rear wall that are generally perpendicular to the load direction, and a lateral wall that connects them, and is supported by a pair of bumper stays from the rear side. It is fixed to the tip of the side member (front or rear).

  Aluminum bumper stays can be broadly divided into vertical and lateral collapse types. As shown in FIG. 9A, the vertical crushing type bumper stay has plate-like mounting flanges 2 and 3 (bumper reinforcements 4 and side members 5 at the front and rear ends of the hollow extruded shape member constituting the shaft portion 1. The direction of the extrusion axis is directed to the longitudinal direction of the vehicle body (substantially perpendicular to the longitudinal direction of the bumper reinforcement 4). As shown in FIG. 9 (b), the lateral crush type bumper stay is composed of an extruded shape member 6 in which mounting flanges 7 and 8 are integrally formed at the front and rear ends, and the extrusion axis direction is the vehicle body vertical direction (bumper reinforcement). (Vertical to the longitudinal direction of 4). Examples of the lateral crush type bumper stay include the following Patent Documents 1 to 3.

JP-A-8-91154 JP 2000-318552 A JP 2001-294106 A

  Vertical crush-type bumper stays are generally high in manufacturing cost because three-piece parts are integrated by welding. Furthermore, as shown in FIG. 9 (a), the bumper reinforcement end mounting location is in the vehicle width direction. When inclined to the rear side, there are problems such as a decrease in yield due to oblique cutting of the shaft extruded section, an increase in cutting cost, and welding cost. In addition, the lateral compression type bumper stay is inexpensive to manufacture and has the advantage that it can be easily accommodated even if the bumper reinforcement end mounting location is inclined or curved with respect to the vehicle width direction. Therefore, there is a problem in that the weight-specific energy absorption amount is small, and a significant lightening effect cannot be obtained.

  On the other hand, the specifications and drawings of Japanese Patent Application Nos. 2002-240366, 2002-357820 and 2002-357820 are made of an aluminum alloy extruded material (pipe material) as shown in FIG. Bumper stays in which mounting flanges 12 and 13 are formed by electromagnetic forming at both ends are described.

  In this bumper stay, as shown in FIG. 10, an extruded aluminum material is cut to a predetermined length to form a raw material tube 14, and a periphery of the raw material tube 14 is a mold 15 for electromagnetic forming (from a plurality of divided dies). The end portion of the material tube 14 protrudes from the end surfaces (molding surfaces) 16 and 17 of the mold 15 and is inserted into the electromagnetic forming coil 18 inserted into the material tube 14 at a high voltage. Manufactured by instantaneously charging (discharging) stored electrical energy (electric charge). Electromagnetic forming means that, by applying electric energy, the electromagnetic forming coil 18 forms a strong magnetic field for a very short time, and the workpiece (workpiece) placed in this magnetic field repels the magnetic field (the left hand of Fleming). In this example, the material tube 14 is strongly expanded by utilizing a plastic deformation at a high speed by receiving a strong expansion force or contraction force by a Lorentz force according to the law of The material pipe 14 is pressed against the inner surface of the through hole 19 inside the end faces 16, 17, and the material pipe 14 is pressed to the end faces 16, 17 outside the end faces 16, 17. 17 is pressed.

Since electromagnetic forming is a high-speed deformation, it is possible to cope with a case where the machining shape is complicated, and there is an advantage that the shape accuracy is good because a predetermined shape is obtained by pressing against the molding surface of the mold. Therefore, by making the end surfaces (molding surfaces) 16 and 17 of the mold 15 into appropriate shapes, not only the flange (flange 13) having a surface perpendicular to the axial direction but also the surface perpendicular to the axial direction. A flange having a shape corresponding to the shape of the mounting surface of the bumper reinforcement or the side member, such as an inclined flange (flange 12) or a flange having a curved surface, can be formed.
In addition, electromagnetic shaping | molding itself is a well-known technique, as described in the following patent documents 4-11.

Japanese Patent Laid-Open No. 58-4601 JP-A-6-31226 JP-A-7-116751 JP-A-9-166111 Japanese Patent Laid-Open No. 10-314869 Japanese Patent Laid-Open No. 11-20434 JP 2000-86228 A JP 2000-264246 A

By the way, looking at the deformation of the bumper reinforcement at the time of collision, for example, the deformation form shown in FIG. 11 is followed (example of pole collision). In this case, in particular, since the end mounting portion of the bumper reinforcement 4 is inclined with respect to the vehicle width direction, the compression force is concentrated on the flange 7 of the bumper stay 6 from the bumper reinforcement 4 to the inside (indicated by A), When a tensile force acts on the outside (indicated by B) and the flange 7 is thin, the plate is deformed, and the bumper reinforcement 4 is rotationally deformed. As a result, the load at the initial stage of the collision is reduced and the amount of energy absorption is reduced. Further, depending on the joining conditions of the flange 7 and the bumper reinforcement 4, there is a problem in that the joining portion is broken outside the flange 7. These problems can occur in the same manner in the longitudinal compression type bumper stay shown in FIGS. 9 (a) and 9 (c).
This can be prevented by increasing the thickness of the flange 7 (or flanges 2 and 12) fixed to the bumper reinforcement 4, but this causes a problem that the weight of the bumper stay increases.

  Also, in general T-joint parts other than bumpers, it is often necessary to ensure the strength and rigidity of the joint. Also in this case, when a predetermined strength cannot be obtained, the strength is improved by attaching a triangular or L-shaped reinforcing material. FIG. 12 shows such an example. In a T-shaped joint part in which two members 21 and 22 are welded, a triangular reinforcing member 23 is shown in (a), and an L-shaped reinforcing member is shown in (b). 24 is welded so that both may be connected. However, even if strength and rigidity can be ensured by this, problems such as an increase in the number of parts, an increase in weight, and an increase in welding cost occur.

  The present invention has been made in view of such problems of the prior art, and aims to improve the strength and rigidity of the flange portion without increasing the weight in a bumper stay having a flange portion for mounting. To do. Another object of the present invention is to improve the strength and rigidity of a flange portion without increasing the weight in a T-shaped joint component having a flange portion for mounting in general.

The tubular member with a flange according to the present invention is a tubular member with a flange having an attachment flange formed at the axial end of an aluminum tube with the tube end portion expanded in the outer diameter direction, and the shaft portion and the attachment flange. An inclined wall that protrudes higher in the outer diameter direction near the shaft end and connects between the shaft portion and the mounting flange is formed at one or two or more locations along the circumferential direction at the boundary and in the vicinity thereof. It is . The front surface of the mounting flange (meaning the surface facing the opposite side of the shaft portion) serves as a mounting surface for other members. In the present invention, aluminum includes an aluminum alloy. The aluminum tube is typically an aluminum extrusion.
The mounting flange and the inclined wall are obtained by expanding the peripheral wall of the end portion of the aluminum tube in the outer diameter direction by electromagnetic forming.

When manufacturing the said flanged tubular member , the end surface which a through-hole opens is made into a shaping | molding surface, and it inclined so deeply that it was near the said end surface in the 1 or 2 or more location along the circumferential direction of the edge part of the said through-hole. Using an electromagnetic forming mold in which a groove is formed, an aluminum tube is accommodated in the through hole, and an end of the aluminum tube is projected from the end surface of the mold by a predetermined length. The peripheral wall in the vicinity thereof is expanded in the outer diameter direction, pressed against the end surface and the groove portion, and formed into a shape along the end surface and the groove portion. At this time, as the aluminum tube, a tube whose cross section does not generally change along the length direction (if the extruded material is not subjected to post-extrusion molding) may be used. Protruding portions protruding in the outer diameter direction in one or several places along the circumferential direction of the peripheral wall are formed in advance, and when the aluminum tube is accommodated in the through hole, the protruding portion fits into the groove portion of the mold, In addition, electromagnetic forming can be performed. Note that the protrusion can be formed by pressing or hydroforming.

In the tubular member with flange according to the present invention, the mounting flange portion is formed by expanding the end portion of the aluminum tube, and the bracing inclined wall connecting the shaft portion and the flange portion is also an aluminum tube. Therefore, the strength and rigidity of the flange portion can be improved without increasing the weight. In particular, when the flange portion or the flange portion and the inclined wall are formed by electromagnetic forming, a necessary shape can be easily obtained with high accuracy.
The flanged tubular member according to the present invention is suitable as, for example, a bumper stay, an instrument panel reinforcement, or other T-shaped joint. Instrument panel reinforcements are also called steering supports, steering hanger beams, and cross-members between pillars. They are arranged in the vehicle width direction, and both ends are fixed to the left and right frames of the vehicle. Instrument panels, ducts, steering columns, etc. Is a member that has a role of securing a occupant's living space against a side collision of a vehicle. For example, JP-A-11-115550, JP-A-2001-63628, JP-A-2001-71939 JP-A-2001-253368 and JP-A-2002-21114 describe a reinforcement for an instrument panel made of an aluminum alloy.

Hereinafter, the flanged tubular member according to the present invention will be specifically described with a bumper stay as an example.
A bumper stay 31 shown in FIG. 1 and FIGS. 2A and 2B is formed by electromagnetic forming from an extruded aluminum material (pipe material), and the axial direction of the shaft portion 32 is formed at the front end of the cylindrical shaft portion 32. And a mounting flange 34 having a surface perpendicular to the axial direction of the shaft portion 32 is integrally formed at the rear end, and the shaft portion 32 and the mounting flange 33 are further formed. Inclined walls 35 that connect the shaft portion 32 and the mounting flange 33 in a bracing manner are formed at two locations along the boundary and in the vicinity of the circumferential direction. The inclined wall 35 has a shape in which the boundary between the shaft portion 32 and the mounting flange 33 and the vicinity thereof protrude obliquely in the outer diameter direction (projected higher in the outer diameter direction as it is closer to the shaft end). The long sides of the two rectangular plates (35a, 35b) form a shape that is in contact with a substantially mountain-shaped cross section at a predetermined angle.

  The inclined wall 35 is formed on the upper side and the lower side of the inclination of the mounting flange 33. As shown in FIG. 3, when the inclined wall 35 is attached to the bumper stay 4 and the side member 5, the inclined wall 35 Come outside. The inclined wall 35 functions as a bracing between the shaft portion 32 and the mounting flange 33, improves the strength and rigidity of the mounting flange, and the mounting flange 33 can be easily made by the compressive force or tensile force applied at the time of collision. The mounting flange 33 is reinforced to prevent deformation. It should be noted that the inclined walls 35 are arranged on the inner side and the outer side in the vehicle width direction, as described above, the compression force or tensile force at the time of the collision is a problem particularly on the inner side and the outer side of the mounting flange 33 in the vehicle width direction. It is to become.

4 to 6 show a method for manufacturing the bumper stay 31 (electromagnetic forming method).
The electromagnetic molding die 36 used has end surfaces 38 and 39 where the through holes 37 open as molding surfaces, one end surface 38 is inclined with respect to the axial direction of the through hole 37, and the other end surface 39 is in the axial direction. Is perpendicular to. At the end portion (end portion on the end surface 38 side) of the through hole 37, a groove portion 41 having an inclined sectional triangle that is deeper toward the end surface 38 is formed on the upper and lower sides of the end surface 38. As shown in FIG. 4, the mold 36 can be divided into four parallel to the axial direction of the through hole 37, and when combined, the end surfaces 38 and 39, the through hole 37 and the groove 41 are formed. The As the mold split structure, it is desirable to have a structure that is split at the apex of the groove 41 to be formed in consideration of the component take-out property after molding.

The aluminum tube 42 used as a raw material is an aluminum alloy extruded material having a circular cross section. As shown in FIG. 5, the outer diameter is substantially equal to the inner diameter of the through hole 37, and one end face 42a is cut obliquely with respect to the axial direction. The other end face 42b is cut in a plane perpendicular to the axial direction. The inclination angle of the end face 42 a is the same as the inclination angle of the end face 38 of the mold 36.
As shown in FIG. 5, the aluminum tube 42 is accommodated in the through hole 37, both end portions thereof are projected from the end surfaces 38 and 39 by a predetermined length, and the end surface 42 a is positioned so as to be parallel to the end surface 38. Then, an electromagnetic forming coil (not shown) is inserted into the aluminum tube 42, and electric energy is input to the electromagnetic forming coil. Thereby, the peripheral wall of the aluminum tube 42 is instantaneously expanded in the outer diameter direction, pressed against the inner surface and the end surfaces 38 and 39 of the through hole 37, and on the side of the end surface 38, the aluminum tube 42 is positioned in the vicinity of the end surface 38 of the aluminum tube 42. A part of the peripheral wall is pressed against the inner surface of the groove 41. Thereby, the bumper stay 31 is formed.

In the example of the bumper stay described above, the inclined walls are formed at two locations on the inner side and the outer side in the vehicle width direction, but the number and positions of the inclined walls can be set as necessary. For example, FIG. 2 (c) shows an example in which a total of four locations are formed on the inside and the outside in the vehicle width direction. In addition, the inclined walls do not necessarily have to be formed in pairs in the vehicle width direction inside and outside, and may be formed in a necessary number and at appropriate positions according to the load resistance requirements of the parts.
Also, the shape of the inclined wall is not limited to the above shape as long as it protrudes higher in the outer diameter direction as it is closer to the shaft end and connects the shaft portion and the mounting flange in a bracing manner.

  In the above example, the aluminum extruded material (pipe material) was subjected to electromagnetic forming without any prior shaping, but may be subjected to electromagnetic forming after being pre-formed. FIG. 7 shows this, and at one or more locations (locations where inclined walls are to be formed) along the circumferential direction in the vicinity of the end of the aluminum tube 42, A protruding portion 43 protruding in the outer diameter direction is formed in advance by press molding or hydroforming (including bulge molding). Then, when the aluminum tube 42 is accommodated in the through hole 37 of the mold 36, the protruding portion 43 is fitted into the groove portion 41 of the mold 36, and then electromagnetic forming is performed. Thereby, when the depth of the groove portion 41 is deep (in other words, when the protruding height of the inclined wall formed on the bumper stay 31 is high), the mold surface (especially the groove portion 41) is accurately aligned. Molding becomes possible.

  FIG. 8 shows another example. A protruding portion 43 formed on the peripheral wall of the aluminum tube 42 so as to protrude in the outer diameter direction reaches the tube end. In this case, there exists an advantage which can shape | mold the protrusion part 43 easily compared with the example of FIG. The procedure of electromagnetic forming is the same as in the example of FIG. 7, so that when the aluminum tube 42 is accommodated in the through hole 37 of the mold 36 (see FIG. 7), the protruding portion 43 fits into the groove portion 41 of the mold 36. To do. Naturally, a part (tube end side) of the protruding portion 43 protrudes from the end surface of the mold 36.

It is a perspective view of the bumper stay concerning the present invention. It is the II sectional view (b) of the top view (a) and (a), and the top view (c) of another bumper stay. It is a top view which shows the attachment state of the bumper stay. It is a perspective view of the electromagnetic forming metal mold | die for manufacturing the bumper stay. It is sectional drawing at the time of electromagnetic forming. It is II-II sectional drawing of FIG. It is the perspective view (a) of the preformed aluminum tube, and sectional drawing (b) when accommodated in a metal mold | die. It is the top view (a) and perspective view (b) of the aluminum pipe which were preformed in other forms. It is a top view which shows the conventional bumper stay and its attachment state. It is sectional drawing explaining the method to manufacture a bumper stay by electromagnetic forming. It is a top view explaining typically the modification of the bumper reinforcement at the time of a collision, and a bumper stay. It is explanatory drawing of a T-shaped joint and a reinforcement member.

Explanation of symbols

31 Bumper stay 32 Shaft portion 33, 34 Mounting flange 35 Inclined wall 36 Electromagnetic molding die 37 Through hole 38, 39 End surface (molding surface)
41 Groove 42 Aluminum tube 43 Projection

Claims (3)

At the shaft end, there is a mounting flange whose front surface is a mounting surface for other members at the shaft end, at one or two or more locations along the circumferential direction at and near the boundary between the shaft portion and the mounting flange. A method of manufacturing a flanged tubular member in which an inclined wall that protrudes higher in the outer diameter direction as it is closer and is formed to connect between the shaft portion and the mounting flange in a brace form, the end surface where the through hole is open is a molding surface And an electromagnetic forming mold in which a groove portion that is deeply inclined toward the end face is formed at one or two or more locations along the circumferential direction of the end portion of the through hole, and an aluminum tube is formed in the through hole. The end portion of the aluminum pipe is protruded by a predetermined length from the end face of the mold, the end portion of the aluminum tube and the peripheral wall in the vicinity thereof are expanded in the outer diameter direction by electromagnetic forming, and pressed against the end face and the groove portion. along the end face and the groove Te Method for manufacturing a flanged tubular member, characterized in that molded into Jo. When one or two or more locations along the circumferential direction of the peripheral wall in the vicinity of the end portion of the aluminum tube are previously formed with a protruding portion protruding in the outer diameter direction, and the aluminum tube is accommodated in the through hole, the protruding portion 2. The method for manufacturing a flanged tubular member according to claim 1 , wherein an electromagnetic forming is performed on the groove of the mold. The method for producing a flanged tubular member according to claim 1 or 2, wherein the flanged tubular member is a bumper stay for automobiles.

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