JP2001191112A - Method and device for forming tubular member having square cross section - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device capable of surely and precisely forming a tubular member having a square cross section over the entire length or in partial part by press forming with a simple configuration. SOLUTION: This forming device 30 is provided with an upper die 31 and lower die 32 as a 1st and 2nd dies for forming corner parts D1-D4 by making each preliminary corner parts d1-d4 to bend to prescribed angles by performing press forming of a twice bent rough shape material p2 on which plural preliminary corner parts d1-d4 are formed and side-face dies 33, 33 as the 3rd die for pressing parts to be made into side-part planes F2, F3 later so as to make edges S which are opposed to each other of the twice bent rough shape material p2 closely when the twice bent rough shape material p2 arranged between the upper die 31 and the lower die 33 is formed by pressing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for forming a tubular member having a rectangular cross section. More specifically, the present invention relates to a method for forming a plurality of corners having a predetermined angle on a plate by pressing the plate. A method of forming a tubular member having a polygonal cross section by bending the opposite edges so that they can be joined together, and a plate material on which a plurality of spare corners having a wider angle than a corner having a predetermined angle are formed. Is formed by press forming, forming each preliminary corner portion into a corner portion of a predetermined angle, and bending so that opposing edges thereof can be joined to form a tubular member having a polygonal cross section. It is about.

[0002]

2. Description of the Related Art In the case of forming a tubular member having a predetermined cross section by bending a plate material, a so-called roll forming is generally performed. In this roll forming, a plurality of sets of forming rolls provided in a predetermined posture are arranged, and a band-shaped plate is fed between each pair of forming rolls, so that the band-shaped plate is successively bent into a predetermined shape. Things. Therefore,
In roll forming, a strip-shaped plate member can be formed into a tubular member having a uniform cross-sectional shape over its entire length. Roll forming has a large load on each set of forming rolls,
It is suitable for bending a plate material having a relatively low plate pressure.

On the other hand, particularly when a tubular member having a circular cross section is formed from a relatively thick plate material, for example, Japanese Patent Publication No.
As disclosed in Japanese Patent No. 50688, the so-called U-
O press molding is performed. In the U-O press forming method, as shown in FIGS. 8 to 12, edge bending is performed by bending both end edges S ′ and S ′ of a flat plate material (FIG. 8) p0 ′ having a predetermined length. C-bended coarse material p1 '
Bending process (FIG. 9) for forming
A U-bending step (FIG. 10) of forming a U-shaped U-bended coarse material P2 'by bending the substantially center of 1' at a predetermined curvature, and a cylindrical tubular member And an O-press step (FIGS. 11 and 12) for molding into P ′. The U-O press forming apparatus for performing each of these steps includes a C-bending press 50, a U-bending press 6
0 and an O press 70.

[0004] As shown in FIG.
Edge edges B ', S' of the plate material p0 'for edge bending
Upper mold 51 and lower mold 52 formed to correspond to
And a cushion 5 that supports a portion between both edges S ′ and S ′ that does not edge bend in the C bending step of the plate material p0 ′ and forms the same surface as the lower mold 52 when the upper mold 51 descends.
3 is provided. An upper end surface of the cushion 53 and a portion of the upper mold 51 facing the cushion 53 are formed substantially flat. When performing the C bending step, the cushion 53 is at the raised position, and the upper mold 51 is lowered so that the plate material p0 ′ maintains its flat shape at the portions other than the both end edges S ′ and S ′. , Flat cushion 5
3 descends together with the cushion 53 in a state of being sandwiched between the upper end surface of the upper mold 51 and a portion of the upper mold 51 facing the cushion 53,
Only both end edges S ′ and S ′ are edge-bent between the lower mold 52 and the upper mold 51, and the C-bended coarse material p1 ′ is formed.

As shown in FIG. 10, a U-bending press 60 includes a cushion 63 and a U-bending punch 61 which are formed so that the center of an edge-bend C-bent rough material p1 'is bent at a predetermined curvature. , C-bended coarse material p
And a lower mold 62 that relatively presses a portion between the edge bent end edges S ′, S ′ of 1 ′ and a center curved at a predetermined curvature. The upper end surface of the cushion 63 is formed in a concave shape, and the lower end surface of the U-bending punch 61 is formed in a convex shape in accordance with the curvature of bending the center of the C-bended rough material p1 ′. When performing the U-bending step, the cushion 63 is in the raised position,
Is lowered, the C-bended coarsely shaped material p1 'is lowered with its center substantially sandwiched between the cushion 63 and the U-bending punch 61, and the edge-bend end edges S', S '. The portion between the center and the center is pressed relatively to the lower mold 62, and only the center is curved in a U-shape with a predetermined curvature, thereby forming a U-bent rough shaped material p2 '. Both end edges S ′ and S ′ of the U-shaped bent material p2 ′ are open because the U-shaped punch 61 is located.

As shown in FIGS. 11 and 12, an O-press 70 is a U-shaped rough material p having both ends S 'and S' edge-bent and a center curved at a predetermined curvature.
An upper mold 71 and a lower mold 72 for molding 2 ′ into a cylindrical tubular member P ′ are provided. When the upper mold 71 and the lower mold 72 are brought close to each other and abut against each other, the tubular member P to be molded is formed.
Is formed in a so-called half-shape in order to form a circular space having an inside diameter substantially the same as the outside diameter of the inside. And
When performing the O-pressing step, the center of the U-shaped coarsely shaped material p2 ', which is curved at a predetermined curvature, is arranged on the lower mold in a state where the upper mold 71 and the lower mold 72 are separated from each other. At this time, since the lower mold 72 is formed in half in order to form the cylindrical tubular member P ', the center of the U-shaped rough material p2' curved at a predetermined curvature is formed in the lower mold 72. It is possible to arrange. Next, by bringing the upper die 71 and the lower die 72 close to each other so as to abut against each other, the edge-bend both end edges S ′ and S ′ of the U-bent rough shaped material p2 ′ are brought into contact with the half-shaped upper die 71. Are brought into close contact with each other, and finally both end surfaces Sa ', Sa'
Are compressed in a state where they are in contact with each other, and are curved so as to buckle along a circular space formed therein by the upper mold 71 and the lower mold 72 to form a cylindrical tubular member P ′. Become.

By the way, the tubular member P 'formed from the plate material as described above is sometimes used as a member to which a relatively large load is applied, such as a trailing arm of an automobile suspension. In order to form a tubular member having a rigidity that can withstand a relatively large load, a certain thickness (plate thickness) is required. Therefore, when forming a thick tubular member, press forming is more suitable than roll forming described above. Further, according to the press molding, as shown in FIG. 13, the cross-sectional shape changes from an ellipse (AA) to a substantially perfect circle (BB, CC), and in the longitudinal direction. A tubular member P ′ having a shape that is not linear but offset can be formed relatively easily.

In recent years, in order to further reduce the weight (reducing the thickness) and increase the rigidity of the member, the cross-sectional shape of the tubular member is formed into a rectangular shape partially or over the entire length as necessary. There was a need. In some cases, as shown in FIG. 1, FIG. 14, or FIG. 15, a hole G is formed in the formed tubular member as needed.

[0009]

However, in the above-mentioned U-O press forming of the prior art, although it can be employed when forming a tubular member P 'having a circular cross section, a rectangular tubular member having a rectangular cross section can be employed. Can not be adopted when molding.

That is, in the case of forming a tubular member P 'having a circular cross section, the center of the U-bended coarsely shaped material p2' is bent at a predetermined curvature during the O-press step of U-O press forming. Therefore, this U-bended rough material p2 ′ is
It is possible to dispose the lower mold half 72 of the press 70.

On the other hand, when such a U-O press forming is applied to forming a tubular member having a rectangular cross section, a flat plate material (material p0) is bent to form as shown in FIG. It is necessary to form a rough material p2 in which preliminary corners d1 to d4 wider than the corners D1 to D4 (see FIG. 1) of the tubular member P having a rectangular cross section are formed. Further, a process for forming a tubular member having a square cross section by press-forming the rough shaped member p2 on which the preliminary corner portions d1 to d4 are formed is performed in the same manner as in forming the tubular member P ′ having a circular cross section. Forming device 8
No. 0 needs to be provided with dies 81 and 82 for forming a space substantially similar to the outer shape of the tubular member having a rectangular cross section to be formed.

However, when forming the preliminary corners d1 to d4, as shown in FIG. 5, the bending punch 21 is located between the both edges S of the raw material p2. The corners d1 to d4 are wider than the corners D1 to D4 of the tubular member P having a rectangular cross section to be formed. Therefore, the coarse material p
Reference numeral 2 denotes a shape in which both ends S, S are opened, and portions that become side planes F2, F3 are inclined. Then, the dies 81 and 82 for press-forming the rough shaped material 2 are formed into a half-split shape like the O-press 70 in the same manner as in the case of forming the tubular member P ′ having a round cross section. In the case of the configuration including the mold 81 and the lower mold 82, as shown in FIG. 15, the rough material p <b> 2 having a shape in which both end edges S, S become the open side planes F <b> 2, F <b> 3 is formed into a half-shape. It cannot be placed in the mold 82.

Further, as shown in FIG. 1, when the tubular member P whose sectional shape is partially changed from the round shape R to the square shape Q is partially formed, the coarsely shaped material p2 is also partially shaped. It is formed into a shape that changes from a U-shaped portion so that the center is curved at a predetermined curvature to a portion where the preliminary corners d1 to d4 are formed. Then, according to the cross-sectional shape of the tubular member P which is formed so as to partially change from a round shape to a square shape,
As in the case of the O-press 70, when the half-shaped upper die 81 and the lower die 82 are formed, as shown in FIG. 14, the coarsely shaped material p2 is formed such that the center thereof is curved at a predetermined curvature. The portion formed in the shape of a letter is disposed in the lower mold 82, and the preliminary corner portion d1 is formed.
The portion where d4 is formed cannot be arranged in the lower mold 82. When the upper die 81 is brought close to the upper die 81 in this state, a portion that cannot be arranged in the lower die 82 partially contacts the upper die 81 due to the formation of the preliminary corners d1 to d4, and a push occurs. As indicated by the arrow Z in FIG. 15, the molding edge is degraded due to the displacement of the edge S of the portion where the preliminary corners d1 to d4 are formed, or the buckling of the portion that becomes the side planes F2 and F3 of the portion. In addition, problems such as molding and defective molding occur. In particular, as shown in FIG. 15, when the holes G are formed in the portions F2 and F3 which are the side planes of the rough material p2, the rough shapes of the portions which become the side planes F2 and F3 are formed. Since the rigidity of the material p2 is reduced, problems such as a reduction in molding accuracy and a defective molding are enormous.

The present invention has been made in view of the above problems, and a method and a method capable of reliably and accurately forming a tubular member having a simple configuration and a rectangular cross section over the entire length or partially by press forming. It is intended to provide the device.

[0015]

According to a first aspect of the present invention, there is provided a method for forming a tubular member having a rectangular cross section. In order to achieve the above object, a corner having a predetermined angle is formed on the plate by pressing the plate. A method of forming a tubular member having a rectangular cross section by forming a plurality and bending so that opposite edges thereof can be joined, wherein each corner is formed at a position where each corner of a plate material is formed. Also, a wide-angle preliminary corner is formed, and a press is performed so that each preliminary corner is bent to a predetermined angle while pressing the opposing edges of the plate material on which the preliminary corner is formed to approach each other. It is characterized by being molded.

According to a second aspect of the present invention, there is provided an apparatus for forming a tubular member having a rectangular cross section. In order to achieve the above object, a plate material having a plurality of pre-angles wider than a predetermined angle is formed by press forming. An apparatus for forming a tubular member having a square cross section by forming each of the spare corners at a corner having a predetermined angle and bending the opposite edges so as to be joined to each other. The first and second molds are formed by press-forming a plate material arranged at a predetermined angle to bend each preliminary corner portion to a predetermined angle, and the first and second molds press-form the plate material. And a third die for pressing the side portion so that the opposing edges of the plate material are brought close to each other.

According to the first aspect of the present invention, the plate is formed into a shape corresponding to the cross-sectional shape of the tubular member to be formed. In the plate material, preliminary corners wider than the corners are formed at positions where the corners will be formed later according to the cross-sectional shape of the tubular member to be formed. Therefore, the plate material at this stage has both end edges separated by welding or the like after forming is completed, and the side portion is wider than the width of the product shape, that is, is wider than the width of the formed portion of the upper die. It is in a state of spreading outward. The sheet material thus formed is pressed so that each of the spare corners is bent to a predetermined angle in a state in which the side portions are pressed to the width of the product shape so that the opposing edges are close to each other. Molded,
A tubular member having a square cross section is formed over the entire length or partially.

According to the second aspect of the present invention, the plate is formed into a shape corresponding to the cross-sectional shape of the tubular member to be formed. In the plate material, preliminary corners wider than the corners are formed at positions where the corners will be formed later according to the cross-sectional shape of the tubular member to be formed.
Therefore, the plate material at this stage has both end edges separated by welding or the like after forming is completed, and the side portion is wider than the width of the product shape, that is, is wider than the width of the formed portion of the upper die. It is in a state of spreading outward. Apparatus for press-forming such a plate material includes first and second apparatuses.
And a pair of third dies provided to face both sides of the plate material to be formed into a square cross section. When the plate is placed between the first and second molds, the third mold is on standby so as not to interfere with the side portion of the plate that is extended outside. Then, the third mold is moved so as to press the side of the plate material to the width of the product, and the first and second dies are brought close to each other to turn the preliminary corner of the plate into a corner having a predetermined angle. Forming and bending so that the opposing edges can be joined together to form a tubular member having a rectangular cross section over the entire length or partially.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an embodiment of the shape of a tubular member having a rectangular cross section formed according to the present invention will be described with reference to FIG. FIG. 1 is a front view showing an embodiment of a tubular member P formed according to the present invention, and its AA, B-
FIG. 2 shows end views at respective points B and CC in correspondence with each other. As can be seen from the end views, the tubular member P to be formed has a longitudinally left portion Q in the front view.
In this embodiment, (AA, BB) is formed into a rectangular cross section having corners D1 to D4, and the right portion R (CC) in the longitudinal direction has been described in the related art. As shown in FIG. In the description of this embodiment, the left portion Q in the longitudinal direction of the tubular member P is formed into a rectangular shape in cross section.
The horizontal plane located at the bottom in the cross-sectional view
For convenience, a vertical plane positioned adjacent to the bottom F1 is defined as a side part F2, F3, and a horizontal plane formed adjacent to the side parts F2, F3 and opposed to the bottom F1 is defined as an upper part F4. I will say that.

Each of the corners D1 to D4 of the left portion in the longitudinal direction Q of the tubular member P formed into a quadrangular cross section is bent so as to have a predetermined radius, and a bottom plane between the corners D1 to D4 is formed. F1, side planes F2, F3, and top plane F4 are:
Each is formed so that a cross section becomes a straight shape. The angle of each corner D1 to D4, that is, the corner D1
The angle formed by the planes F1 to F4 adjacent to .about.D4 is set to be substantially a right angle as a predetermined angle. In this embodiment, both end edges S, S which are later joined by welding or the like form a horizontal plane by abutting the end surfaces Sa, Sa at the center of the upper plane F4 in the width direction. . Further, in the tubular member P having a rectangular cross section in this embodiment, the left portion Q in the longitudinal direction formed into a square cross section and the right portion R in the longitudinal direction formed into a round cross section are linearly aligned in the longitudinal direction. It is molded so that it is not offset. In the left portion Q in the longitudinal direction formed into a quadrangular cross section, an end portion Qa opening leftward and an end portion Qb opening upward are formed, and a hole G is formed in a side surface plane. I have.

A rectangular section Q of such a tubular member P
An embodiment of the molding method of the present invention will be described with reference to FIGS. 3 to 7.
1 shows a cross section at the position of BB in FIG. The forming method of the present invention generally includes a preliminary corner d having a wider angle than each corner D1 to D4 at a position where each corner D1 to D4 of the plate material p is formed.
1 to d4 are formed, and the preliminary corners d1 and d2 are formed at a predetermined angle while pressing the opposing edges S and S of the plate material p2 on which the preliminary corners d1 to d4 are formed to approach each other. A plurality of corners D1 to D4 having a predetermined angle are formed by press molding so as to bend the sheet material p2 so that the opposing edges S, S can be joined. is there.

First, as shown in FIGS. 2 and 3, the plate material p is formed into an outer shape corresponding to the shape of the tubular member to be formed, for example, by punching a flat steel plate having a predetermined thickness. (Hereinafter, this flat plate material is referred to as a material p0). In addition, as shown in FIG. 2, holes are formed in the raw material p0 at the same time as the outer shape is formed, according to the necessity such as the purpose of use of the tubular member to be formed.

The raw material p0 formed in this way, and later 4
At the positions where the corners D1 to D4 are formed, as shown in FIG. 4, preliminary corners d1 to d4 having a wider angle than the corners D1 to D4 formed in the tubular member P are subjected to one bending press. 10 are formed at substantially equal angles in a single stroke. In the following description, the plate material p in a state where the preliminary corners d1 to d4 are formed at an equal angle to the material p0 is formed by bending the plate material p by one bending.
One. The one-bending press 10 includes an upper mold 11 formed to correspond to the preliminary corners d1 to d4 formed on the material p0, a lower mold 12 and a cushion 13. When the upper mold 11 descends, the upper end surface of the cushion 13 descends while supporting the material p0 between the upper mold 11 and the upper mold 11 to form a molding surface that is continuous with the lower mold 12. When performing the forming process of the 1 bending material p1, the cushion 13 is initially at the raised position, and the upper die 11 is lowered,
The material p0 descends together with the cushion 13 in a state of being sandwiched between the upper mold 11 and the cushion 13, and is bent at four places between the upper mold 11 and the lower mold 12 and the cushion 13 connected thereto. , Preliminary corner portions d1 to d4 having substantially equal angles
Is formed. In addition, the portion corresponding to the portion R on the right side in the longitudinal direction where the cross section is formed into a circle of the 1 bending press 10 is:
This is the same as the conventional technique (see FIG. 9), and thus the description thereof is omitted.

Next, as shown in FIG. 5, in this embodiment, the one-bended coarsely shaped material p1 is divided into two preliminary corners d1, adjacent to the center of the tubular member P having a cross-section having a rectangular cross section at the bottom plane F1.
Only d2 is further cornered by a two-bending press 20 to form a corner D
It is bent at an angle smaller than the angle of 1, D2. In the following description, a plate material in a state where the preliminary corner portions d1 and d2 of the 1-bended coarse material p1 are further bent is referred to as a 2-bended coarse material p2. 2
The bending press 20 has a bottom plane F after one bending coarse section p1.
A punch 21 for pressing the center, which is 1;
1 to further bend the two preliminary corners d1 and d2,
That is, a lower mold 22 formed so as to be inclined so that the outside becomes closer to the outside more vertically from the center which will later become the side planes F1 and F2, and a cushion 23 for holding the one-bended coarse material p1 between the punch 21 and the lower mold 22. It has. Cushion 23
When the punch 21 descends, the upper end surface thereof descends while supporting the one-bend coarse shaped material p1 between the punch 21 and forms a molding surface continuous with the lower mold 22. When performing the forming process of the 2nd bent material p2, the cushion 23 is initially in the raised position, and the 1st bent coarse material p1 is sandwiched between the punch 21 and the cushion 23 by lowering the punch 21. The lower corner 22 lowers together with the cushion 23, and the lower die 22 further bends the two preliminary corners d1 and d2 adjacent to the center, which will later become the bottom plane F1, so that the side portions between the center and the side edges are further bent. The planes F2 and F3 incline so that the portions become closer to vertical. However, in this step,
Due to the presence of the punch 21 for pressing the center serving as the bottom plane F1, the two end edges S of the two-bend rough profile p2 cannot be closed so that they can be joined to each other, and are separated from each other and open. It has become. The right-hand portion R in the longitudinal direction of the 2 bending press 20 whose cross section is formed into a circular shape.
Are the same as those in the related art (see FIG. 10), and thus description thereof will be omitted.

[0025] The two-bend rough shaped material p2 thus formed
As shown in FIGS. 6 and 7, in a state where the edges S are pressed so as to approach each other, each of the spare corners d1 to d4 is bent until a predetermined angle (substantially right angle) is formed by press molding. And each corner D1 to D4 of the tubular tubular member P having a rectangular cross section.
Is formed. Hereinafter, a case where this step is performed by the molding device 30 of the tubular member P having a rectangular cross section of the present invention will be described.

An apparatus 3 for forming a tubular member P having a rectangular cross section according to the present invention.
0 is roughly 2 in which a plurality of preliminary corners d1 to d4 are formed.
Press forming of the bent rough shaped material p2, and each of the preliminary corners d1 to d
Upper and lower dies 31 and 32 as first and second dies for forming corners D1 to D4 by bending 4 to a predetermined angle
And, when press-forming the two-bend coarse profile p2 disposed between the upper die 31 and the lower die 32, the side planes are rearwardly moved so that the opposing edges S of the two-bend coarse profile p2 are brought close to each other. Side dies 33, 33 are provided as a third die for pressing the portions to be F2 and F3.

The upper die 31 presses both end edges S, S of the two-bend rough shaped material p2, and finally the both end surfaces Sa, Sa are brought into contact with each other to form a horizontal upper plane F4. And an inclined portion 31b for guiding the bending of the preliminary corners d3, d4 adjacent to the both end edges S, S. The upper die 31 is attached to a ram (not shown) of the press. Further, the lower die 32 is formed so as to position and support a portion to be the bottom plane F1 of the two-bend coarsely shaped material p2. The lower mold 32 is attached to a press bed or a bolster (not shown). Further, the side dies 33 are formed as a pair, and are supported on the upper surface of the lower mold 32 so as to be movable in the left-right direction in FIGS. 6 and 7. By moving as shown by the arrow H in FIG. 2
The portions F2 and F3, which become inclined side planes so as to open the bent coarse shaped material p2, are pressed until they are substantially vertical, and both end edges S, S of the two bent rough shaped material p2 separated from each other are brought close to each other. In this embodiment, as shown in FIG.
Since the left side Q in the longitudinal direction is formed into a rectangular cross section continuously from the circular section R formed to the right in the longitudinal direction of the tubular member P, the side surface is formed in accordance with the section Q formed into the rectangular cross section. The dies 33 are arranged.

The ram of the press (not shown) is provided with moving cams 34, 34 integrally or separately from the upper die 31, and the upper die 31 and the lower die 32 are close to the side dies 33, 33. A cam surface 33a for pressing the portions where the side dies 33, 33 sometimes move to become the side planes F2, F3 of the two-bend rough profile p2 is formed corresponding to the shift cam 34, respectively. Furthermore, in the lower mold 32,
A backup surface 32a is formed to prevent the approach cam 34 from bending when the approach cam 34 is moved while contacting the cam surface 33a of the side die 33. Also,
The inclined part 31 of the upper die 31 is provided on the inner upper surface of the side die 33.
The side die 33 is provided with a lock portion 33b for preventing the side die 33 from being deformed or moved so as to escape to the outside by being engaged.

The tubular member P having a rectangular cross section thus constructed
First, in the state in which the upper die 31 is separated from the lower die 32 and the side dies 33, 33 are spread so as to be separated from each other, the bottom plane F1 of the two-bend coarse material p2 is placed on the lower die 32. Place the central part where

Next, when the ram of the press (not shown) is driven to descend, first, the double-sided cam 34 is moved to the dies 33 on both sides.
6, the side die 33 moves in the direction indicated by the arrow H in FIG. 6, and the two-bend coarsely shaped material p2 has the inclined side planes F2, F3 having vertical portions. And the side dies 33 until the preliminary corners d1 and d2 adjacent to the part to be the bottom plane F1 are substantially perpendicular.
As a result, the edges S, S that have been pressed and separated from each other come closer to each other.

Subsequently, when the ram is further driven downward, 2
Edges S, S of the bent rough shaped material p2 in the state of being close to each other are brought into contact with the inclined portion 31b of the upper die 31, and the side planes F2, F
3 and preliminary corners d3, d4 between the edges S, S
Is bent at a right angle, and both end surfaces Sa, Sa
Move close to each other while facing each other along the horizontal forming portion 31a, and finally butted against each other with a slight compressive stress applied thereto, thereby forming a horizontal upper plane F4. Therefore, the tubular member P having a rectangular cross section can be reliably and accurately molded with a small molding load, and there is no possibility that the planes F1 to F4 between the corners D1 to D4 will buckle, thereby causing poor molding or poor precision. The butted end surfaces Sa are joined by welding or the like in a later step. In the present invention, FIG.
As shown in the above, even when forming a tubular member having a complicated shape such that the left portion Q in the longitudinal direction formed into a square cross section has an end portion Qb opening upward, the vertical portion Edge forming a wall (see Sv in FIG. 14)
As a result, the complicated tubular member P can be surely formed by press forming.

In the apparatus 30 for forming a tubular member P having a rectangular cross section,
Since the side die 33 is positioned so as to spread and stand by when setting the two-bend coarse material p2 in the lower die 32, as shown in FIG.
There is no such thing as not being able to accommodate the 2nd, and the 2nd bent rough material p2 can be set to the lower mold 32 reliably. When forming the corners D1 to D4 from the preliminary corners d1 to d4 by bringing the upper mold 31 close to the lower mold 32, the side planes F are formed so that the edges S and S are close to each other.
By pressing the portions that become F2 and F3 with the side dies 33, the molding load applied to the side portions F2 and F3 is small.
Even if the hole G is drilled in advance in the portion that becomes F3,
The bored hole G is not deformed. Therefore, the hole G can be formed simultaneously with the formation of the outer shape of the material p0 without forming the hole G in a separate step after the formation of the tubular member P having a rectangular cross section. The process can be simplified.

In the embodiment described above, as shown in FIG. 1, the right and left sides of the tubular member in the longitudinal direction are:
Although a case where a circular section and a rectangular section are continuously formed has been described above, the present invention is not limited to this embodiment, and a case where a tubular member having a rectangular cross section over the entire length is formed. It goes without saying that it can also be applied to. In addition, the present invention relates to a corner D
The present invention is not limited to the case where the cross section has a square shape having 1 to D4, and can be applied to the case where a tubular member having another polygonal cross section is formed.

[0034]

According to the first aspect of the present invention, each spare corner is bent to a predetermined angle while pressing the opposing edges of the plate material on which the spare corners are formed so as to approach each other. Thus, it is possible to provide a method capable of reliably and accurately forming a tubular member having a rectangular cross section over its entire length or partially by press forming with a simple structure of press forming.

According to the second aspect of the present invention, the first and second dies are formed by press-forming a plate material disposed therebetween, and bending each spare corner to a predetermined angle to form a corner. The first
And a third mold that presses the side portions so that the opposing edges of the plate material are close to each other when the second mold press-forms the plate material. It is possible to provide an apparatus capable of reliably and accurately forming a tubular member having a rectangular cross section by press forming.

[Brief description of the drawings]

FIG. 1 is a front view and a cross-sectional view corresponding to each portion for explaining the shape of a tubular member formed by the present invention.

FIG. 2 is a development view showing a material for forming a tubular member having the shape shown in FIG.

FIG. 3 is a sectional view of a material taken along line BB shown in FIG. 1;

FIG. 4 is a cross-sectional view for explaining a one-bending press for forming a preliminary corner portion on the material shown in FIG. 3;

FIG. 5 is a cross-sectional view for explaining a two-bending press for further bending a preliminary corner portion adjacent to the bottom of the one-bend rough shaped material shown in FIG. 4;

FIG. 6 is a cross-sectional view showing one embodiment of the apparatus for forming a tubular member having a rectangular cross-section according to the present invention, showing a state in which the side dies are moved by an approach cam and the edges of the two-bend coarsely shaped material come close to each other. FIG.

FIG. 7 is an explanatory view showing a state when a tubular member having a rectangular cross section is formed from the state of FIG. 6;

FIG. 8 is a cross-sectional view of a material for explaining a conventional technique for forming a tubular member having a circular cross section.

FIG. 9 is a cross-sectional view showing a process using a C-bending press for edge-bending both edges of the material shown in FIG. 8;

FIG. 10 is a view showing a U for bending the approximate center of the edge-bent C-curved coarse material shown in FIG. 9 at a predetermined curvature.
It is sectional drawing which showed the process by a bending press.

FIG. 11 is a cross-sectional view showing a state where the U-shaped roughly shaped material whose center is substantially curved at a predetermined curvature shown in FIG. It is.

12 is a cross-sectional view showing a state in which an upper die and a lower die of the O-press shown in FIG. 11 are abutted to form a tubular member having a cylindrical cross section from a U-bent crude material.

FIG. 13 is a front view and a cross-sectional view corresponding to each portion for explaining the shape of a tubular member that can be formed by the steps shown in FIGS. 8 to 12;

FIG. 14 illustrates a state in which the two-bend coarsely shaped material shown in FIG. 5 or FIG. 6 is set in the O-press shown in FIG. 11 and FIG. 12 in order to form the tubular member having the shape shown in FIG. FIG.

FIG. 15 is a sectional view taken along line BB of FIG. 14;

[Explanation of symbols]

 P tubular member Q section of polygonal section D1 to D4 corner d1 to d4 preliminary corner F1 to F4 plane S side edge 30 forming device 31 upper mold (first mold) 32 lower mold (second mold) 33 side face Dies (third type) 33a Cam surface 34 Approach cam

Claims (2)

[Claims] 1. A plate material having a rectangular cross section is formed by press forming a plate material to form a plurality of corners having a predetermined angle on the plate material and to bend such that opposing edges thereof can be joined. A method of forming a member, comprising forming a preliminary corner having a wider angle than each corner at a position where each corner of the plate is formed, and forming opposing edges of the plate on which the preliminary corner is formed. A method for forming a tubular member having a rectangular cross-section, wherein press forming is performed such that each preliminary corner is bent to a predetermined angle while being pressed close to each other. 2. A plate material having a plurality of spare corners wider than a corner of a predetermined angle is formed by press forming, and each of the spare corners is formed into a corner of a predetermined angle, and opposite edges thereof. This is a device for forming a tubular member having a rectangular cross section by bending so that it can be joined, press forming a plate material disposed therebetween, and bending each spare corner to a predetermined angle. First and second forming corners
And when the first and second molds press-form the plate material,
A third die for pressing a side portion of the plate member so that opposing edges are brought close to each other, and a device for forming a tubular member having a rectangular cross section.