JP2002263747A - Tubular member manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tubular member manufacturing method for manufacturing a tubular member product by the hydraulic forming such as blow molding out of a stock tube formed by the working including at least extrusion which has small distortion in the hydraulic forming, is free from any cracks on the surface, and has excellent wall thickness accuracy. SOLUTION: The tubular member having an outer shape copying the inner surface shape is manufactured by extruding a tube stock 40, placing the tube stock 40 in a die 50 having the predetermined inner surface shape, blow-molding the tube stock 40. The tubular stock 40 is formed so that the circumferential length ratio which is the ratio of the circumferential length (La+Lb) of an inner surface 53 at the section of the die 50 to the circumferential length L1 of an outer surface 43 at the section of the tube stock 40 is in a range between 1 and 1.11 in the state the tube stock 40 is fixed to the predetermined position in the die 50. In addition, the tube stock 40 has curved wall parts 41c1 , 41c2 , 41d1 and 41d2 for suppressing elongation of the tube stock 40 during the blow molding.

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 example, a tubular member used as a member constituting a body frame, from a tube material formed by a process including at least extrusion molding.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a tubular member from a tube material, a method of manufacturing a hollow member disclosed in Japanese Patent Application Laid-Open No. Hei 10-230318 is known. In this manufacturing method, using a mandrel, a hollow material made of an aluminum alloy having a different cross-sectional shape in the longitudinal direction (hereinafter, referred to as a “tube material”) is extruded, and then the tube material is placed in a mold,
By bulging, the inside of the tube material is pressurized to bulge the tube material along the inner surface of the mold, and a hollow member such as a swing arm of a motorcycle (hereinafter, referred to as a “tubular member”).
To manufacture.

[0003]

By the way, in bulge molding, since the material is expanded along the inner surface of the mold, distortion occurs in the formed member depending on the degree of shape change due to the expansion at that time. As a result, cracks may occur on the surface. Therefore, in order to obtain a tubular member as a product having a desired shape by subjecting a tube material to bulge forming as in the conventional technique, it is preferable that the material of the tubular member has a certain degree of ductility. The use of such a material prevents the occurrence of cracks due to distortion in bulge forming, but the tube material is deformed with relatively large distortion by bulge forming. It is difficult to secure wall thickness accuracy.

The present invention has been made in view of such circumstances, and a method of manufacturing a tubular member as a product by fluid pressure molding such as blow molding from a tube material formed by processing including at least extrusion molding. In the above, an object of the present invention is to provide a method for producing a tubular member which has a small distortion at the time of fluid pressure molding, has no cracks on the surface, and has good wall thickness accuracy.

[0005]

Means for Solving the Problems and Effects of the Invention According to the first aspect of the present invention, after a tube material is formed by processing including at least extrusion molding, the tube material is placed in a mold having a predetermined inner surface shape. And forming the tubular material into a tubular member having an outer surface shape following the inner surface shape by fluid pressure forming by applying a fluid pressure to a hollow portion of the tubular material. With the tube material fixed at a predetermined position in the mold, the metal mold in a plane including the cross section with respect to the circumferential length of the outer surface of the tube material at an arbitrary position in the longitudinal direction. This is a method for manufacturing a tubular member to be molded such that a circumferential ratio, which is a ratio of the circumferential length of the inner surface in the cross section of the mold, is in the range of 1 to 1.11.

According to the first aspect of the present invention, the tube material formed by processing including extrusion forming has a circumference ratio of 1 to 5.
Since the pipe material is formed so as to be within the range of 1.11, the pipe material is hardly distorted by the fluid pressure forming, or even if the strain is generated, the strain is small, so that cracks are generated on the surface. Thus, a tubular member having good wall thickness accuracy after fluid pressure forming can be easily obtained without largely depending on the type of material of the tubular member from the viewpoint of ductility.
Further, since the circumference ratio is 1 to 1.11, the pipe material is less likely to be deformed while being pressed against the mold by the supplied high-pressure fluid, and the pipe when the high-pressure fluid is supplied is reduced. Wear of the inner surface of the mold due to friction generated between the tube material and the mold due to the deformation of the material is greatly reduced, so that the durability of the mold is improved.

According to a second aspect of the present invention, in the method for manufacturing a tubular member according to the first aspect, the two tube wall portions of the tube material facing each other in a direction orthogonal to a specific direction in a cross section are formed by:
Over the entire length in the longitudinal direction, it has a curved wall portion that curves in the orthogonal direction, and the width of the outer surface in the cross section of the tube material in the specific direction is a predetermined position in the mold in the mold. In such a state, the width of the inner surface in the cross section of the mold is smaller than the width in the specific direction over the entire length in the longitudinal direction.

According to the second aspect of the present invention, the width of the tube material in a specific direction is determined in a specific direction of the mold while the tube material is fixed at a predetermined position in the mold. Is formed so as to be smaller than the width of the tube, so that the tube material can be easily accommodated in the mold, and even though the width in the specific direction is reduced, the two opposed tubes are formed. Due to the curved wall portion of the wall portion, it is possible to suppress the occurrence of distortion of the tube material at the time of fluid pressure forming, and it is possible to maintain the set circumference ratio.

According to a third aspect of the present invention, in the method for manufacturing a tubular member according to the first or second aspect, the fluid pressure forming is performed to bend the pipe blank around a direction orthogonal to the longitudinal direction. Is what you do.

According to the third aspect of the present invention, since the pipe material is bent by the fluid pressure forming, the tubular members having various shapes according to the needs can be manufactured easily and at low cost. it can.

According to a fourth aspect of the present invention, in the method for manufacturing a tubular member according to the second or third aspect, a curved concave portion is formed in the tube material by the fluid pressure forming.

According to the fourth aspect of the present invention, when the tubular member is used, the concave portion for avoiding the interference with the member disposed close to the tubular member and the appearance for improving the appearance are provided. The concave portion can be formed by fluid pressure molding, and the occurrence of distortion can be suppressed by the curved wall portion of the tube wall despite the fact that a concave portion is easily formed in the tube material during fluid pressure forming. As a result, the set circumference ratio can be maintained, so that various tubular members according to needs can be easily manufactured.

In this specification, the “section” of the tube material means a cross section in a plane perpendicular to the extrusion direction or the longitudinal direction of the tube material. “Polymerize” means to overlap.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 9 show a first embodiment of the present invention. FIG. 1 shows a tubular member 60 manufactured by a manufacturing method according to the present invention. , A fourth tube wall portion 61a, 61b, 61c, 61d, and is used as a member for forming a body frame of a motorcycle, for example.

Hereinafter, referring to FIGS. 2 to 9, a tube material 40 (see FIG. 8) is formed by extrusion, and then the tube member 40 is manufactured by blow molding which is a fluid pressure molding. The apparatus and method will be described. First, an extruder 1 for extruding a tube material 40 as a material for manufacturing the tubular member 60 will be described. As shown in FIG. 2, the extrusion molding apparatus 1 includes a container 3 for accommodating an aluminum alloy which is a molding material (a billet) 2 of a tube material 40, an extrusion die 4, and a dummy for extruding the molding material 2 from the container 3. A block 5 and a stem 6 for transmitting a force generated by the ram to the dummy block 5 are provided. The extrusion die 4 is polymerized on the fixed male die 7 fixed to the container 3, the fixed female die 8 fixed on the fixed male die 7 by polymerization, and the fixed female die 8.
A movable die 10 that is slidable along the overlapped surface, and these dies 7, 8, and 10 are moved in the extrusion direction A0 of the molding material 2;
Are sequentially arranged. The fixed male die 7 and the fixed female die 8, which are combined and integrated with each other, form a fixed die 9, and the movable die 10 is orthogonal to the extrusion direction A0 in this embodiment. The driving device 11 moves the fixed die 9 along the overlapping surface in a first direction A1 as a specific direction. Reference numeral 12 denotes a flow path provided in the fixed male die 7 to guide the molding material 2 to an opening 30 described later.

Referring to FIGS. 3 to 6, the fixed female die 8 is provided with a tube material 40 as shown in FIG.
Outer surface shape, that is, the peripheral wall surface that defines the outer shape of the tube material 40
A through-hole 13 having a peripheral wall 14 is formed in the extrusion direction.
It is formed parallel to A0. Referring also to FIG. 3, in the through-hole 13, a fixed core 15 provided on the fixed male die 7 via the support portion 7 a is arranged with a gap formed between the fixed core 15 and the peripheral wall surface 14.

The peripheral wall 14 has a first peripheral wall 14a and a second peripheral wall
A peripheral wall portion 14b, and a third peripheral wall portion 14c and a fourth peripheral wall portion 14d that are opposed in a second direction A2 perpendicular to the first direction A1 in a cross section (on an orthogonal plane perpendicular to the extrusion direction). . The third peripheral wall portion 14c is continuous via the step portion 14c1,
A first flat portion 14c2 and a second flat portion 14c3, both of which are parallel to the first direction A1 in cross section, one end is continuous with the first flat portion 14c2, and the other end is continuous with the first peripheral wall portion 14a. It comprises a curved surface portion 14c4 that curves and protrudes in one direction (leftward in FIG. 6) in the direction A2. The fourth peripheral wall portion 14d includes a flat surface portion 14d1 parallel to the first direction A1 and a curved surface portion 14d2 curved in the same direction as the curved surface portion 14c4. In the through hole 13, the width in the second direction A2 on the side of the first peripheral wall portion 14a on the side of the first peripheral wall portion 14a in the first direction A1 and the stepped portion 14c1 is equalized in the first direction A1, and The width is smaller than the width in the second direction A2 on the 14b side.

The fixed core 15 has a stepped portion in the first direction A1.
It extends to 14c1, and within that range, the width in the second direction A2 is constant. Further, the fixed core 15 has a cross section in the first direction
A1 linear first end surface 15a facing the first peripheral wall portion 14a at A1
A linear second end face 15b facing the second peripheral wall portion 14b in the first direction A1, a third end face 15c facing the third peripheral wall portion 14c in the second direction A2, and a second direction A2. It comprises a fourth peripheral wall portion 14d and a fourth end surface 15d facing the fourth peripheral wall portion 14d. And the third end face 15c
Is a curved surface portion 15c1 facing the curved surface portion 14c4 and a first flat surface portion.
14c2 and the opposing flat part 15c2, and the fourth end face 15d
It has a curved surface portion 15d1 facing the curved surface portion 14d2 and a flat surface portion 15d2 facing the flat surface portion 14d1.

Thus, the fixed core 15 is moved in the first direction.
A gap of a predetermined width between the first and second peripheral wall portions 14a and 14b at A1
d1 and d2 are respectively formed, and the third peripheral wall portion 14 is formed in the second direction A2.
c, the first flat portion 14c2 and the curved surface portion 14c4, and the fourth peripheral wall portion 1
Air gaps d3 and d4 each having a predetermined width are formed between the plane portion 14d1 and the curved surface portion 14d2 of 4d. And these gaps d1 ~
Fixed core 15 and peripheral wall arranged in through hole 13 including d4
A fixed die hole 16 is formed by a gap formed between the fixed die hole 16 and the fixed die hole 16. The predetermined width of each of the gaps d1 to d3 is appropriately set according to the thickness of the tubular member 60 and the like. For example, the predetermined width of the gap d1, the gap d3, and the gap d4 may be equal.

On the other hand, as shown in FIG. 6B, the movable die 10 has a through hole 13 and a fixed core
15 through the center point of the through hole 13 in the first direction A1 in the second direction
The first, second, third and third portions have a shape inverted with respect to the straight line extending to A2, and thus constitute the peripheral wall surface 18 of the through hole 17.
Fourth peripheral wall portion 18a, 18b, 18c, 18d and third peripheral wall portion 18
The step 18c1 and the first and second plane portions 18c2, 18c3 that constitute c.
And the flat surface portion 1 forming the curved surface portion 18c4 and the fourth peripheral wall surface portion 18d
8d1, curved surface portion 18d2, first to fourth end surfaces 19 of movable core 19
a, 19b, 19c, 19d, a curved surface portion 19c1 facing the curved surface portion 18c4 at the third end surface 19c and a flat surface portion 19c2 facing the second planar portion 18c3, a curved surface portion 19d1 facing the curved surface portion 18d2 at the fourth end surface 19d, and The form and width of each of the gaps d5 to d8 formed between the plane part 19d2 facing the plane part 18d1 and the movable core 19 are set similarly to the corresponding parts of the fixed die 9. A movable die hole 20 is formed by a void formed between the movable core 19 and the peripheral wall surface 18 disposed in the through hole 17 including the voids d5 to d8.

Note that the first of the fixed core 15 and the movable core 19
The width in the direction A1 is such that the fixed die 9 and the movable die 10
When polymerized as shown in FIG. 7A described later, both cores 1
5 and 19 are appropriately set so that the portions near the step portions 14c1 and 18c1 overlap.

The movable core 19 extends from a part of the movable die 10 as shown in FIGS. 3 to 5, and has a support hole 7a formed in the support portion 7a of the fixed male die 7 and the fixed female die 8. And is integrally fixed to a rod-shaped connecting member 10a extending linearly in the first direction A1 via a supporting portion 19e.

Then, as shown in FIG. 7A, the first peripheral wall portions 14 of the peripheral wall surfaces 14 and 18 of the through holes 13 and 17 are formed.
The fixed die 9 and the movable die 10 are positioned with a, 18a in the first direction A1, and the plane portions 14d1, 18d1 of the fourth peripheral wall portions 14d, 18d in the second direction A2, respectively.
When superposed on the superposed surface, the superposed portion of the fixed core 15 and the movable core 19 comes into surface contact with each other (see FIG. 3), and furthermore, the opening is caused by the overlapping of the fixed die hole 16 and the movable die hole 20 in the extrusion direction A0. The portion 30 is formed, and the molding material 2 is extruded through the opening 30 to form the tube wall 41 of the tube material 40. In FIG. 7, the fixed die 9 and the movable die 10 are shown by different hatchings, the portions shown in white are the openings 30, and the portions where both hatches overlap are the portions where the fixed die 9 and the movable die 10 overlap. Is shown.

Referring also to FIG. 6, the opening 30 includes a first pipe wall opening 30a defined by the gap d1 and a gap d6.
And a second tube wall opening 30b facing the first tube wall opening 30a in the first direction A1, a gap d3 and a gap d7.
The third tube wall opening 30c is defined by the following formula, and faces the third tube wall opening 30c in the second direction A2, and has a gap d4 and a gap d8.
And a fourth tube wall opening 30d defined by

The third tube wall opening 30c is defined by a gap between the curved surface portion 14c4 of the third peripheral wall surface portion 14c and the curved surface portion 15c1 of the fixed core 15 in the second direction A2. Curved wall openings
30c1 and a second curved wall opening 30c2 defined by a gap in the second direction A2 between the curved surface portion 18c4 of the third peripheral wall portion 18c and the curved surface portion 19c1 of the movable core 19, 4 pipe wall opening 30d
A third curved wall opening 30d1 formed by a gap in the second direction A2 between the curved surface portion 14d2 of the fourth peripheral wall portion 14d and the curved surface portion 15d1 of the fixed core 15; There is a fourth curved wall opening 30d2 defined by an air gap in the second direction A2 between the curved surface portion 18d2 of the movable core 19d and the curved surface portion 19d1 of the movable core 19.

Further, the third tube wall opening 30c is formed by the first flat portion 14c2 of the third peripheral wall portion 14c and the flat portion 15c2 of the fixed core 15.
In the second direction A2 and the second gap between the second flat portion 18c3 of the third peripheral wall portion 18c and the flat portion 19c2 of the movable core 19.
It has a first plane wall opening 30c3 defined by a gap in the direction A2, and the fourth tube wall opening 30d is formed by a plane part 14d1 of the fourth peripheral wall part 14d and a plane part 15d2 of the fixed core 15. Between the air gap in the second direction A2 and the plane portion 18d1 of the fourth peripheral wall portion 18d and the movable core 1
It has an opening 30d3 for a second plane wall defined by a gap in the second direction A2 between the second plane wall 19d2 and the nine plane parts 19d2.

Next, with reference to FIGS. 7 and 8, a description will be given of a method of forming the tube material 40 by the extrusion molding apparatus 1 using the extrusion dies 4. FIG. First, from the state shown in FIG. 7 (A), the speed ratio of the moving speed of the movable die 10 to the extrusion speed is set to a predetermined speed ratio, and while the molding material 2 is pushed out from the opening 30 by the ram, FIG. B) (see the position of the movable die 9 shown by the two-dot chain line in FIG. 3) until the driving device 11 moves the movable die 10 along the overlapping surface in one of the first directions A1 (in FIG. (Upward) continuously. As a result, as shown in FIG. 8, the first and second tube wall openings 30a and 30b form the first and second tube wall portions 41a and 41b having a predetermined width and the third and third tube wall portions, respectively. , The fourth tube wall openings 30c, 30d form third and fourth tube walls 41c, 41d having a predetermined thickness, and the first to fourth tube wall portions 41a to 41d form the tube wall 41. Be composed. Then, the third and fourth pipe wall portions 41
c, 41d have first to fourth curved wall openings 30c1, 30c2, 30d1,
The first, second, third, and fourth curved wall portions 41c1, 41c2, and 4 are formed by 30d2.
1d1 and 41d2 are respectively formed, and the first and second plane wall portions 41c3 and 41d3 parallel in the second direction A2 are formed by the first and second plane wall openings 30c3 and 30d3. A hollow portion 42 of the tube material 40 is formed by the fixed core 15 and the movable core 19 which are superimposed, and the respective end faces 15a, 15b, 15c, 19b, 19 of the cores 15, 19 are formed.
The inner surface shape, that is, the inner shape of the tube material 40 is defined by c and 19d.

At this time, the width B1 in the first direction A1 between the first peripheral wall portion 14a and the second peripheral wall portion 18b that defines the outer diameter of the tube material 40 in the first direction A1 (see FIG. 9). ) Decreases in proportion to the amount of movement of the movable die 10, and the cross-sectional shape of the tube material 40 differs in the longitudinal direction. The width in the second direction A2 between the outer surface of the third tube wall 41c and the outer surface of the fourth tube wall 41d, which is the outer diameter of the tube material 40 in the second direction A2, was kept constant. It is.

As a result, the second tube wall 41b is pushed in the pushing direction A0.
The first tube wall portion 41a, which is parallel to the first tube wall portion 41a, is formed as a tapered wall inclined so as to gradually approach the first tube wall portion 41a.
40 has a width in the second direction A2 equal to the longitudinal direction,
The tapered tube has a variable cross section in the longitudinal direction such that the width B1 at A1 gradually decreases from the extrusion start end 40a to the extrusion end end 40b in the longitudinal direction. The wall thickness of each of the tube wall portions 41a to 41d of the tube material 40 becomes constant in the longitudinal direction.

Here, referring also to FIG.
40 is an outer surface 43 in a cross section at any position in the longitudinal direction
The circumferential length L1 of the tube material 40 is fixed to a predetermined position for performing the blow molding with respect to the blow mold 50, and the mold 50 in a plane including a cross section at the arbitrary position is set. The circumference L2 of the inner surface 53 of the cross section (this circumference is the first mold
51 is the sum of the circumferential length La of the inner surface 53a of the cross section 51 in the cross section and the circumferential length Lb of the inner surface 53b of the second mold 52 in the cross section. That is, in consideration of the circumference of the outer circumference in the cross section of the tubular member 60 as a product, the circumference ratio, which is the ratio of the circumference L2 to the circumference L1, is a length that satisfies Expression (1). The opening 30 is formed by setting the shape and speed ratio. L2 / L1 = 1 to 1.11 (1) That is, when the circumferential length ratio is 1, distortion when the tube material 40 is formed into the tubular member 60 by blow molding hardly occurs. No cracks occur,
Moreover, the thickness accuracy is hardly affected, and the best result can be obtained. Further, for example, when the wall thickness of the tube material 40 which is an extruded material is set to 2 mm by design, if the circumference ratio is greater than 1 and not more than 1.11, the wall thickness normally obtained by extrusion molding is used. The wall thickness accuracy of the tubular member 60 after blow molding the pipe blank 40 having an accuracy of 2 mm ± 0.2 can satisfy the JIS standard of 2 mm ± 0.38. In addition, tube material 40
In the case where the wall thickness in the design is other than 2 mm, as the circumferential length ratio is larger than 1 or closer to 1, even if distortion occurs in the tube material 40 by blow molding, the distortion is small. Thus, the tubular member 60 having no cracks and good wall thickness accuracy can be obtained.

Further, in a state where the tube material 40 is fixed at the predetermined position with respect to the mold 50, the tube material is
The width B1 of the outer surface 43 in the first direction A1 of the outer surface 43 in the cross section of 40, that is, the outer diameter of the tube material 40 in the first direction A1, extends over the entire length in the longitudinal direction, and 53 is formed to be smaller than the width B2 in the first direction A1.

Next, the tube material 40 thus extruded is set in a molding space of a mold 50 for performing blow molding, as shown in FIG. The mold 50 has an inner surface shape for forming a tubular member 60 as a product. In FIG. 9, the mold 50 is divided into a first mold 51 and a second mold 52.
Are shown before being joined together.

As shown in FIG. 1, the first mold 51 has a third tube wall portion extending over the entire length of the tubular member 60 in the longitudinal direction.
The inner surface 53a of the tube material 40 facing the third tube wall 41c so that the concave portion 61c1 curved to 61c is formed along the longitudinal direction.
A curved surface portion bulging toward the second mold 52 in the second direction A2.
53a1 is provided along the longitudinal direction. Meanwhile, the second mold
As shown in FIG. 1, the first tube wall portion 61a and the fourth tube wall portion 6 have a portion 52 in a part of the longitudinal direction of the tubular member 60, as shown in FIG.
A curved surface (not shown) is provided on a part of the inner surface 53b so that a curved concave portion 61e is formed at the corner formed by 1d. Further, the inner surface 53 of the mold 50 is formed such that the tube material 40 is bent around the second direction A2 in a predetermined range in the longitudinal direction of the tube material 40.

In setting the tube material 40 in the mold 50, first, when the tube material 40 is put into the mold 50, the tube material
Since the width B1 of the 40 in the first direction A1 is smaller than the width B2 of the inner surface 53 of the mold 50, the tube material 40 can be easily housed in the molding space. Then, in a state where the tube material 40 is fixed at the predetermined position, one end of the tube material 40 is closed, and a high-pressure fluid is supplied to the hollow portion 42 of the tube material 40 from the other end, and a high-pressure fluid is applied to the inner surface of the tube material 40. The outer shape of the tube material 40
The pipe material 40 is plastically deformed so as to follow the inner surface shape of the tube. At this time, the tube material 40 tries to be distorted in the first direction A1, and also tries to be distorted following the curved surface portion 53a1, but the occurrence of the distortion is as follows.
Since the first to fourth curved wall portions 41c1, 41c2, 41d1, 41d2 of the tube material 40 are suppressed by being deformed, the set circumference ratio can be maintained. Thus, the concave portion 6 curved around the longitudinal direction in the third tube wall portion 61c shown in FIG.
1c1 has concave portions 61e at the corners of the first and fourth tube wall portions 61a and 61d,
Furthermore, the tubular member 60 in which the first and second tube wall portions 61a and 61b have curved portions 61a1 and 61b1 curved around the second direction A2 is formed.

Next, the operation and effect of the embodiment configured as described above will be described. A tube material 40 extruded by the extruder 1 and having a different cross-sectional shape in the longitudinal direction.
Is formed so that the circumference ratio is in the range of 1 to 1.11. Therefore, almost no distortion occurs in the tube material 40 by blow molding, or even if distortion occurs, the distortion is small. Therefore, the tubular member 60 having no crack on the surface and having good wall thickness accuracy after blow molding can be easily obtained without largely depending on the type of the material of the tubular member 60 from the viewpoint of ductility. In addition, since the tube material 40 may be formed by extrusion so that the circumference ratio is in the range of 1 to 1.11, as long as the outer surface 43 satisfies the circumference ratio, the tube material 40 is used as a product. It is not always necessary to form the tube material 40 into a shape similar to the shape of the tubular member 60, and the shape of the tube material 40 can be simplified. As a result, the extrusion molding apparatus 1 does not have a complicated structure, does not require advanced control, has little or no distortion, has no cracks on the surface, and The manufacturing cost of the tubular member 60 having good wall thickness accuracy can be reduced, and the shape of the tubular member 60 is less subject to the restriction of the shape of the tube material 40, and the tubular member having various shapes according to needs is reduced. 60 can be manufactured. Further, when the circumference ratio is 1 to 1.
11, which is smaller than conventional blow molding,
Since the abrasion of the inner surface 53 of the mold 50 due to the friction between the tube material 40 and the mold 50 based on the deformation of the tube material 40 when the high-pressure fluid is supplied, the durability of the mold 50 is improved. .

The pipe blank 40 has a width B1 in the first direction A1.
In a state where the tube material 40 is fixed at the predetermined position in the mold 50, the tube material is extruded so as to be smaller than the width B2 of the mold 50 in the first direction A1. 40 can be easily accommodated, and despite the reduced width B1 in the first direction A1, the opposed third and fourth tube wall portions 41
The first to fourth curved wall portions 41c1, 41c2, 41d1, 41d2 of c and 41d make it possible to suppress the occurrence of distortion of the tube material 40 during blow molding, and maintain the set circumference ratio. can do.

Since the tube material 40 is bent by the fluid pressure molding, it is easy to form the tubular member 60 having various shapes according to needs, such as improvement in appearance when applied to a frame of a motorcycle. And at a low cost.

When the tubular member 60 is used, the tubular member
The recess 61e for avoiding interference with members arranged close to 60 and the recess 61c1 for improving appearance can be formed by blow molding, and moreover, the blow-up of the tube material 40 occurs during blow molding. The first to fourth curved wall portions 41c1, 41c2, 41d1, 41d2 despite the easy forming of the concave portions 61c1, 61e.
As a result, the generation of the distortion can be suppressed, and the circumference ratio can be maintained, so that various tubular members 60 according to needs can be manufactured easily and at low cost.

In the extrusion molding apparatus 1, the third and fourth tube walls 41c and 41d of the tube material 40 are both in the cross section in the first direction.
Since the first and second plane walls 41c3 and 41d3 are parallel to A1, the first direction A1 for forming the plane walls 41c3 and 41d3 is provided.
Using the fixed die 9 and the movable die 10 having the first and second plane wall openings 30c3 and 30d3 extending in parallel to, the molding material 2 is extruded from the opening 30 for forming the tube wall 41,
By moving the movable die 10 in the first direction A1, it has first to fourth curved wall portions 41c1, 41c2, 41d1, 41d2, and is defined by the first peripheral wall portion 14a and the second peripheral wall portion 14b. Pipe material
Since the tube material 40 having a variable cross section in which the width of the tube material 40 in the first direction A1 changes can be easily manufactured by extrusion, the productivity of the tube material 40 can be improved and the cost can be reduced.

Hereinafter, an embodiment in which a part of the configuration of the first embodiment is changed will be described with respect to the changed configuration. In the first embodiment, the tube material 40 has first and second curved wall portions 41c1, 4 curved toward the first mold 51 at both ends in the first direction A1.
The third tube wall portion 41c formed with 1c2 has a concave shape, and is in the first direction.
The fourth tube wall portion 41d formed with the third and fourth curved wall portions 41d1 and 41d2 curved toward the first mold 51 at both ends in A1 has a convex shape. As shown in the second embodiment, when compared with the tube material 40, the first, second, third and third
First and second curved wall portions 71c in which the third tube wall portion 71c of the tube wall 71 including the fourth tube wall portions 71a, 71b, 71c, and 71d curves toward the second mold 52.
Molded to have a convex shape with 1,71c2,
Together with a fourth tube wall 71d having fourth curved wall portions 71d1 and 71d2,
The two tube wall portions 71c and 71d may be a tube material 70 having a convex shape, and further, as in the third embodiment shown in FIG.
When compared with the tube material 40, the fourth tube wall portion 81d of the tube wall 81 including the first, second, third, and fourth tube wall portions 81a, 81b, 81c, 81d.
Are curved toward the second mold 52, third and fourth curved wall portions 81d1, 81d2.
And the third tube wall 81c having the first and second curved wall portions 81c1 and 81c2, and the two tube wall portions 8c.
1c, 81d may be a tube material 80 having a concave shape. Both of the tube materials 70 and 80 can be easily extruded by using the extrusion die 4 including the fixed die 9 and the movable die 10 similar to the tube material 40.
In the second and third embodiments, the same operation and effect as those of the first embodiment can be obtained.

In the first embodiment, a connecting wall extending in the longitudinal direction and connecting the third and fourth tube walls 61c and 61d facing each other in the second direction A2 is provided inside the tube wall 61.
In order to manufacture the tubular member 60 having a high rigidity by increasing the second moment of area, an opening for a connecting wall is provided in the fixed die 9 or the movable die 10 of the extrusion die 4, and the blow-molded tubular member is formed. The length of the connecting wall of the member 60 in the second direction A2, that is, the second direction A2 of the third and fourth tube wall portions 61c and 61d.
The connecting wall is formed in the tube material 40 by extrusion in consideration of the width of the pipe. For example, the third and fourth pipe wall portions 61 of the tubular member 60
When the width of the c and 61d in the second direction A2 is larger than the width of the third and fourth pipe wall portions 41c and 41d of the tube material 40 in the second direction A2,
As shown by a two-dot chain line in FIG. 9, by forming a connecting wall 41 f having an appropriate bent portion 41 f 1 that allows the width to be increased during blow molding in the tube material 40, the tubular member 60 is substantially flat. The connecting wall having a shape and a thickness substantially equal to the thickness of the connecting wall 41f can be formed. In addition, the number of connection walls may be single or plural.

Similarly, in order to increase the rigidity of the tubular member 60, one or more ribs extending in the longitudinal direction may be formed on the inner surface of the tube wall 61. Such a rib has a smaller rigidity increase than the connecting wall, but has a tubular member.
The required rigidity can be secured depending on the 60 use locations,
As shown by a two-dot chain line in FIG. 9, by forming a rib 41 g on the tube material 40 by extrusion, it is possible to form a rib having substantially the same shape in the tubular member 60, and a high-pressure fluid is supplied. In the blow molding, there is an advantage that the influence on the fluidity of the supplied fluid is less than that of the connection wall. The connecting wall or rib described above can be formed in the second and third embodiments in the same manner as in the first embodiment.

In each of the above embodiments, two curved wall portions are formed on the third and fourth tube wall portions 41c, 41d, 71c, 71d, 81c, 81d of the tube materials 40, 70, 80, respectively. The wall portion may be provided at one place, and the first and second tube wall portions 41a, 41b, 71a, 71b, 81
A curved wall portion can be formed on each of the a and 81b, and one or more curved wall portions can be extruded on at least one of the first to fourth partition portions depending on the shape of the tubular member as a product. It may be formed by molding.

In each of the above embodiments, the fixed die 9 is fixed to the container 3. However, the fixed die is configured to be movable with respect to the container 3 and both dies are movable dies. The two dies can be moved in opposite directions by a driving device so that the tube walls facing each other in the first direction A1 are both tapered walls inclined in the longitudinal direction.

In each of the above embodiments, the width of the tube material in the first direction A1 monotonously decreases continuously in the longitudinal direction from the extrusion start end, but increases and decreases in the longitudinal direction. Is also good. Further, by changing the speed ratio while the molding material 2 is being extruded, it is possible to mold a tube material having a portion where the inclination angle of the tapered wall is different. Further, a portion having a constant cross section can be formed with the speed ratio being zero.

In the above embodiment, the fluid pressure forming for forming the pipe blank into a predetermined shape by plastically deforming the pipe blank by the fluid pressure acting on the pipe blank was performed by blow molding. Alternatively, another plastic working method using fluid pressure may be used. Further, the molding material of the tubular member may be a metal other than the aluminum alloy.

In each of the above embodiments, both the tube material 40 and the tubular member 60 have irregular cross sections, but at least one of the tube material 40 and the tubular member 60 has a constant cross-sectional shape in the longitudinal direction. You may have. Also,
In each of the above embodiments, the tube material 40 having a circumference ratio of 1 to 1.11 was formed only by extrusion molding.
An intermediate material is formed by extrusion molding, a swaging process is performed on the intermediate material to form a tapered tube, and thereafter, a processing strain is removed by annealing treatment, and a tube material having a circumference ratio of 1 to 1.11. For example, a tube material having a circumferential length ratio of 1 to 1.11 may be formed by a series of processes including at least extrusion forming, and further including one or more other plastic workings.

The tubular member can be used as a member constituting a body frame of a motorcycle or a swing arm, and further, a body frame of a vehicle other than the motorcycle, and a structural material of a machine other than the vehicle. Can be used as

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention, and is a perspective view of a tubular member manufactured by a manufacturing method according to the present invention.

FIG. 2 is a sectional view of a main part of an extrusion molding apparatus for molding a tube material for producing the tubular member of FIG.

FIG. 3 is an enlarged view of a main part of an extrusion die of the extrusion molding apparatus of FIG. 2;

FIG. 4 is a sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is a sectional view taken along line VV of FIG.

6A is a plan view illustrating a positional relationship between a fixed die hole and a fixed core in a fixed die, and FIG. 6B is a plan view illustrating a positional relationship between a movable die hole and a movable core in a movable die.

FIG. 7 is a plan view illustrating a positional relationship between the fixed die and the movable die when the movable die is moved by overlapping the fixed die and the movable die.

FIG. 8 is a perspective view of a tube material for manufacturing the tubular member of FIG. 1;

FIG. 9 is a view showing a state where the tube material of FIG. 8 is arranged in a mold.

FIG. 10 is a view showing a second embodiment of the present invention and corresponding to FIG. 9 of the first embodiment.

FIG. 11 is a view showing a third embodiment of the present invention and corresponding to FIG. 9 of the first embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Extrusion molding apparatus, 2 ... Molding material, 3 ... Container, 4 ... Extrusion die, 5 ... Dummy block, 6 ... Stem, 7 ... Fixed male die, 8 ... Fixed female die, 9 ... Fixed die,
10: movable die, 11: drive device, 12: flow path, 13: through hole, 14: peripheral wall, 15: fixed core, 16: fixed die hole, 17
… Through hole, 18… peripheral wall surface, 19… movable core, 20… movable die hole, 30… opening, 40… tube material, 41… tube wall, 41c1, 41c2, 4
1d1, 41d2: curved wall portion, 42: hollow portion, 43: outer surface, 50: mold, 51: first mold, 52: second mold, 53: inner surface, 60: tubular member, 61: tube wall, 61c1, 61e: recess, 70: tubular member, 71
... tube wall, 80 ... tubular member, 81 ... tube wall, A0 ... extrusion direction, A1 ...
First direction, A2: second direction, d1 to d8: gap, B1, B2: width.

Claims (4)

[Claims] 1. After forming a tube material by a process including at least extrusion molding, the tube material is placed in a mold having a predetermined inner surface shape, and a fluid pressure is applied to a hollow portion of the tube material. A method for manufacturing a tubular member, wherein the tube material is formed into a tubular member having an outer surface shape following the inner surface shape by molding, wherein the tube material is fixed in a predetermined position in the mold. Then, the circumferential length ratio which is the ratio of the circumferential length of the inner surface of the mold in a plane including the cross section to the circumferential length of the outer surface in a cross section at an arbitrary position in the longitudinal direction of the tube material is 1 A method for producing a tubular member, characterized in that the tubular member is molded so as to fall within the range of ~ 1.11. 2. The two tube wall portions of the tube material opposing each other in an orthogonal direction orthogonal to a specific direction in a cross section have a curved wall portion curved in the orthogonal direction over the entire length in the longitudinal direction. Then, the width of the outer surface of the tube material in the cross section in the specific direction in the specific direction is, in a state where the tube material is fixed at a predetermined position in the mold, over the entire length in the longitudinal direction, of the mold. The method for manufacturing a tubular member according to claim 1, wherein the tubular member is formed so as to have a width smaller than a width of the inner surface in the cross section in the specific direction. 3. The method for manufacturing a tubular member according to claim 1, wherein the pipe material is subjected to bending in a direction perpendicular to the longitudinal direction by the fluid pressure forming. 4. The method for manufacturing a tubular member according to claim 2, wherein a curved concave portion is formed in the tube material by the fluid pressure forming.