JP3343793B2 - Manufacturing method of weight-shaped deformed tube with sharp corners - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a weight-shaped deformed tube having sharp corners by roll forming.

[0002]

2. Description of the Related Art Steel pipes having various irregular cross-sections are used as materials for decorative structures, such as fences, car stops, bridge railings, sashes, etc., which require aesthetics and strength. Above all,
As shown in FIG. 2, a deformed tube having a weight-shaped cross-section with a constricted central portion and fan-shaped both sides is used for a glass window frame, a glass door frame, a handrail, and the like. Weight shaped tubes are
Since it has a unique cross-sectional shape, a roll forming method using a cylindrical tube as a base material cannot be applied, and it has been manufactured by roll forming or bending forming. In roll forming, bending forming, etc.,
After a flat plate as a base material is formed into a predetermined weight-shaped cross section, both ends in the width direction are butted or overlapped and welded.

[0003]

When a flat plate is formed into a closed tube, a portion into which another member is incorporated at the time of construction, that is, a facing portion protruding inside the tube, so that the welded portion does not impair the appearance. A weld is provided on one of the two sides. At this time, it is common to perform superposition welding from the viewpoint of strength. However, if the two opposing sides are small,
The technically impossible welding places restrictions on the shape and dimensions of the mass-shaped profiled tubes that can be manufactured. Therefore, a method of manufacturing a weight-shaped deformed pipe by roll forming a cylindrical pipe so as to eliminate the need for welding has been partially studied. But,
In a roll forming method using a cylindrical tube as a base material, a curved surface portion having a large area is formed at a corner portion, and it is difficult to obtain a weight-shaped deformed tube having a sharp feel required for a decorative tube or the like. As shown in FIG. 1A, the corner of the deformed pipe is a flat portion Sf adjacent to the flat portion Sf via the curved surface portion Sc. The length of the curved surface portion Sc along one flat surface portion Sf is a radius stop Rd, and the radius of the curved surface portion Sc is a gauge radius R.
The shape characteristic of the corner portion is usually represented by the size of the radius stop Rd and the gauge radius Rg as g.

[0004] The curved surface portion S of a deformed tube obtained by simply molding a cylindrical tube
c is a plane part S at a continuous point Pc as shown in FIG.
f is smoothly connected. The resulting deformed tube has a roundness Rd substantially equal to the gauge radius Rg and is a product lacking a sharp impression. However, as shown in FIG. 1 (c), a deformed pipe used as a material for a decorative structure is required to sharply form a corner portion by reducing a round stop Rd. In this case, the curved surface portion Sc is connected to the flat surface portion Sf at the discontinuous point Pd,
It is smaller than the curved surface portion Sc in FIG.
When the mandrel is inserted into the inside of the deformed pipe and roll-formed, the round stop Rd can be reduced. However, the use of a mandrel introduces various problems, including a mandrel holding mechanism during the molding process. For this reason, the productivity is reduced, and this is not a practical solution for manufacturing a deformed pipe on an industrial level. The present invention has been devised to solve such a problem, and a curved surface portion previously attached to a rectangular tube is formed at a corner portion by using a small corner portion as a corner portion of a weight-shaped deformed tube as it is. It is an object of the present invention to produce a weight-shaped deformed tube having a reduced curved surface portion and improved design and distinction by a roll forming method with high productivity.

[0005]

In order to achieve the object, a method for manufacturing a weight-shaped deformed pipe according to the present invention applies a pressing force to two opposing sides of a rectangular pipe having sharp corners.
The two sides are pushed into the inside of the tube without changing the corner angle of the corner portion, and the remaining two sides are extended outside the tube, and are roll-formed into a weight-shaped cross section.
In the rectangular tube as a starting material, two opposing sides are concave portions of the weight-shaped deformed tube, and the remaining two sides are arc-shaped portions on both sides. Therefore, the cross-sectional shape and dimensions of the rectangular tube are determined according to the cross-sectional shape of the weight-shaped deformed tube to be manufactured. The rectangular tube is prepared from a tube material, a plate material, or the like by various methods such as a method of bending and forming a fixed-length band plate, a method of rolling a coiled band plate, and a method of rolling a cylindrical tube. Any rectangular tube manufactured by any method can be used as long as it has a sharp corner portion, in other words, a corner portion having a reduced curved surface portion Sc shown in FIG.

As a means for reducing the curved surface portion Sc, there is a method for reducing the round stop Rd. For example, in the case of a rectangular tube obtained by roll forming of a cylindrical tube, a base tube having two opposing sides projecting outward is used, and the two sides are pushed into the inside of the tube to form a round corner R at the corner.
d can be reduced during roll forming. In this case, the weight-shaped deformed tube can be roll-formed following the forming into a rectangular tube having a corner portion with a small radius stop Rd. Also, by reducing the gauge radius Rg, the curved surface portion Sc becomes small, and a deformed tube giving a sharp impression can be obtained. By setting the radius stop Rd or the gauge radius Rg to a plate thickness or less, preferably 0.8 times or less of the plate thickness, the curved surface portion Sc can be reduced.

[0007]

The process of forming a weight-shaped deformed pipe will be examined separately for the corner 1 and the side. The corner portion 1 is formed as a result of being greatly bent, and the degree of work hardening is larger than that of the side. Reducing the radius of the corner portion 1 causes the already hardened corner portion 1 to be further bent. Even if the pressing force F by the roll is applied under this condition, the deformation of the side portion toward the inside of the deformed pipe has priority over the sharp forming of the corner portion 1 unless some constraint is imposed. In a tube having a cross-sectional shape such as a rectangular tube having no concave portion protruding inward, deformation to the inside of the deformed tube is restrained by attaching a curvature that protrudes outward to the side. However, in the weight-shaped deformed pipe having the concave portion 2 protruding inward, the pushing force applied to the corner portion 1 acts as a force to further deform the concave portion 2 inward, and the curved surface of the corner portion 1 is reduced. Does not work to do.

In the corner portion 1, there is a metal flow during molding as shown in FIG. The pushing force F _d downward on roll 3, when the right roll 4 Add leftward pushing force F _l base tube 5, specific metal flow in the corner portions 1 of the weight-shaped profiled pipe occurs. The metal flow 6 is a one-way flow from right to left and further from the top through the corner 1. On the other hand, the metal flow 6 generated when the rectangular pipe is formed is a flow from both sides toward the corner 1 as shown in FIG. Therefore, in a rectangular tube, the radius stop Rd of the corner portion 1 or the gauge radius R
g tends to be small. Due to the metal flow 6 peculiar to the weight-shaped deformed pipe shown in FIG. 3, the pushing force of the rolls 3 and 4 promotes the metal flow 6 along one direction, but effectively acts to form the sharp corner portion 1. do not do. As a result, the concave portion 2 falls further downward, and the accuracy of the shape of the obtained deformed pipe decreases.

In the present invention, taking advantage of the fact that the corner portion 1 is easily formed sharply by the metal flow 6 shown in FIG. 4, a tube having a rectangular cross section, such as a square cross section, in which the corner portion is preformed sharply is used. I do. That is,
As shown in FIG. 5, when a pressing force F is applied to opposing sides 7 _u and 7 _d of the square tube 7 having sharp corners 7 _c , the square tube 7 remains in accordance with the inward deformation of the upper side 7 _u and the lower side 7 _d. two sides 7 _r, 7 _l of is flared outwardly naturally. As a result, the deformed tube 8 having the target weight-shaped cross section is obtained. Here, the corner portion 7 _c of the square tube 7, odd-shaped pipe 8
Corner portion _8c . Therefore, it is necessary to prevent the shape of the corner portion _7c from becoming large in the process of transforming the square tube 7 into the weight-shaped deformed tube 8. To prevent change in shape of the corner portion 7 _c is a square tube 7
Add the deformation force for bending the only sides 7 _a to _7-d in the process of deforming the weight type profiled tube 8 from. As a result, the corner portion 7 _c is made only causes a rotational movement M, Corner angle θ
Will not change. Therefore, the weight-shaped deformed tube 8 is
Has a pre-attached corner section 8 sharp corner portions 7 _c is reflected the _c in a square tube 7, as a product that gives a sharp impression.

[0010]

EXAMPLE A cylindrical tube of 50.0 mm in outer diameter, 1.0 mm in wall thickness and 1 m in length made of unannealed stainless steel SUS304 was used as a raw tube 9, and a weight was formed using a deformed tube forming machine 10 shown in FIG. Shaped tubes were manufactured. As shown in FIG. 6, the deformed pipe molding machine 10 has molding stands 11 to 15 arranged in five stages, and the raw tubes 9 are sequentially pushed into the molding stands 11 to 15 by the hydraulic cylinder 16. The first molding stand 11
As shown in FIG. 7, upper and lower rolls 1 with concave crowns
1 _u , 11 _d and left and right rolls 11 _r , 11 _l are combined. The raw pipe 9 includes rolls 11 _u , 11 _d , 11
When passing through the space defined by the peripheral surfaces of _r and 11 _l ,
Deforms to follow the surface of each roll. As a result, the upper side 9 _1u, lower 9 _1d and the left and right sides 9 _1r, 9 _1l is formed into a first shape 9 ₁ having a curved surface is convex outward.

As shown in FIG. 8, the second forming stand 12 includes upper and lower rolls 12 _u and 12 _d and left and right rolls 12 _u .
_A flat roll is used for both _r and 12 _l . When blank pipe is passed through the rolls _{12 u, 12 d, 12 r} , 12 space portions partitioned by the circumferential surface of the _l, deformed into a second shape 9 ₂ having a rectangular cross-section following the respective roll circumferential surface. At this time, the upper and lower sides 9 _1u and 9 _{1d of} the first shape are pushed into the inside of the tube to become flat sides 9 _2u and 9 _2d , and the left and right sides 9 _1r and 9 _1l are also pushed into the inside of the tube and become flat. Side 9 _2r ,
It becomes 9 _2l . Therefore, cause metal flow described in FIG. 4, the sides 9 _2u, 9 each corner 9 formed between the _2d
2c is sharply formed.

A third shaping stand 13, as shown in FIG. 9, the second to push the shape 9 ₂ of the upper edge 9 _2u and bottom 9 _{2d, u} roll 13 over which the diameter of the central portion is increased and the lower roll _13d . Left and right rolls 13 _r , 13
_l is a concave crown that keeps the left and right sides 9 _2r and 9 _2l that are extended according to the indentation deformation of the upper side 9 _2u and the lower side 9 _2d . As a result, the rolls 13 _u , 13 _d , 13 _r , 13
The third shape 9 ₃ raw tube passing through the space portions partitioned by the circumferential surface of _l consists of upper 9 _3u and the lower side 9 _3d and right 9 _3r and the left side 9 _3l overhanging outwardly curved inwardly Become a cross section. At this time, the left and right rolls 13 _r and 13 _l have their roll peripheral surfaces facing the upper and lower rolls 13 _u and 13 _{d at} right angles. Therefore, the second shape 9 ₂ corners 9 _2c is
Without changing the corner angle, the third shape 9 ₃ corners 9 _3c.

[0013] fourth molding stand 14, further pushing the third shape 9 ₃ of the upper edge 9 _3u and the lower side 9 _3d, to the large recessed upper 9 _4u and the lower side 9 _4d the tube side, as shown in FIG. 10 An upper roll 14 _u and a lower roll 14 _d having semicircular raised portions 14 _up and 14 _dp formed in the center are used. On both sides of the raised portions 14 _up and 14 _dp are curved surfaces 14 _uc and 14 _dc continuous with the peripheral surfaces 14 _rc and 14 _lc of the right roll 14 _r and the left roll 14 _l with concave crowns. Peripheral surface 14 _rc ,
In 14 _lc and the curved surface 14 _uc, 14 _dc, fourth shape 9 ₄ of the right-hand side 9 _4r and left 9 _4l curved at a predetermined curvature are formed. The surfaces of the ridges 14 _up , 14 _dp and the curved surfaces 14 _uc , 14
angle between the _dc is designed as a corner angle with the third shape 9 ₃ of the corner portion 9 _3c is unchanged. Fifth forming station 15 is a stand for molding the base tube from the fourth shape 9 ₄ Fourth shape 9 ₅ final. As shown in FIG. 11, an upper roll 15 _u and a lower roll 15 _d curved at a predetermined curvature on both sides of a central raised portion having a semicircular cross section, and left and right rolls 15 _r having concave crowns having the same curvature. , 15 _l
Are combined.

[0014] In the molding station 11 and 12, as shown in FIG. 12, the square tube with small corner 9 _2c of the outer surface of the rounded blind and a gauge radius 0.8 times and 1.0 times, respectively thickness 9 _t Was molded. This square tube was roll-formed by the forming stands 13 to 15 to produce a weight-shaped deformed tube having a cross section shown in FIG. The corner portion 9 _5c of the resultant weight-shaped profile tube, had the same are blind and gauge are as those attached to the corner portion 9 _2c of the square tube. For comparison, the cross section of the cylindrical tube was gradually made closer to the weight-shaped cross section by a multi-stage forming stand without going through a square tube forming step of forming a corner portion in advance. At this time, the third stand (FIG. 9), the fourth stand (FIG. 10), and the fifth stand (FIG. 11) were used. Although profiled tube produced has a weight-section, rounded blind and gauge rounded corners 9 _5c had both increased 2.0 times the plate thickness 9 _t. Therefore, the sharpness of the corner portion _95c was clearly inferior to that of the weight-shaped deformed tube formed according to the present invention.

[0015]

As described above, in the present invention, the corner angle of the sharp corner portion previously attached to the rectangular tube is brought into the corner portion of the weight-shaped deformed tube without being changed during the forming process. I have. Therefore, a product with excellent sharpness and high designability and distinctiveness can be obtained. In addition, since it is manufactured by a roll forming method that does not require a welding step, productivity is also increased.

[Brief description of the drawings]

[Fig. 1] Corner of deformed pipe

Fig. 2 Cross section of weight-shaped deformed tube

FIG. 3 shows the metal flow at the corner in the conventional method of roll-forming a weight-shaped deformed tube.

Fig. 4 Metal flow at the corner when a rectangular tube is roll-formed

Fig. 5 Cross-sectional comparison between rectangular tube and target weight shaped deformed tube

FIG. 6 is a profile tube forming machine used in the embodiment of the present invention.

FIG. 7: Forming roll of the first forming stand

FIG. 8: Forming roll of the second forming stand

FIG. 9 is a forming roll of a third forming stand.

FIG. 10: Forming roll of the fourth forming stand

FIG. 11 is a forming roll of a fifth forming stand.

Fig. 12 Rectangular tube with sharp corners

FIG. 13 is a weight-shaped deformed tube obtained in an example.

[Description of Signs] 9: Raw tube 10: Deformed tube molding machine 11: First
Molding stand 12: Second molding stand 13: Third
Molding stand 14: Fourth molding stand 15: Fifth
Forming stand 16: Hydraulic cylinder _11u- 1
5 _u: upper roll 11 _d ~15 _d: lower roll 11 _r ~1
5 _r : right roll 11 _l to 15 _l : left roll 14 _up , 14 _dp : semi-circular ridge 14 _uc , 14 _uc : curved surface 14 _rc , 14 _{lc on} both sides of semi-circular ridge Circumferential surface 9 ₁ : first shape 9 ₂ : second shape 9 ₃ : third
Shape 9 _4: Fourth shape _{9 1u, 9 2u, 9 3u} , 9 4u: upper _{9 1d, 9 2d, 9 3d} , 9 4d: lower _{9 1r, 9 2r, 9 3r} , 9 4r: right 9 _1l,
9 _2l , 9 _3l , 9 _4l : _Left side 9 ₂ : Second shape 9 _2u : _Upper side 9 _2d : Lower side 9 _2r : _Right side 9 _2l : _Left side 9 _2c ,
9 _3c, 9 _4c: corners 9 _5: 5 shape (final shape) Sf: flat portion Sc: curved portion Pc: Continuous point Pd: discontinuity Rd: Earl blind Rg: Gauge Earl F: pressing force M: Corner Rotational motion θ: Corner angle

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Tsutomu Higashi 1 Tsurumachi, Amagasaki-shi, Hyogo Nisshin Steel Co., Ltd. Processing Technology Laboratory (56) References JP-A-54-99069 (JP, A) JP-A-63 -220922 (JP, A) JP-A-4-312209 (JP, A) Japanese Patent Publication No. 45-1344 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21C 37/15

Claims (3)

(57) [Claims] 1. A pressing force is applied to two opposing sides of a rectangular tube having sharp corners, and the two sides are pushed into the inside of the tube without changing the corner angle of the corner, and the remaining two sides are connected to the tube. A method of manufacturing a weight-shaped deformed tube with sharp corners that protrude outward and are roll-formed into a weight-shaped cross section. 2. The manufacturing method according to claim 1, wherein a rectangular tube whose curved surface at the corner is reduced by roll forming is used. 3. The method for producing a weight-shaped deformed pipe according to claim 1, wherein the step of forming a rectangular pipe having a smaller curved surface portion at the corner portion from the cylindrical tube is carried out continuously from the step of forming the tube.