JP2527296B2 - Square pipe manufacturing method - 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 manufacturing a square pipe used for building members and decorations, and more particularly to a method for manufacturing a square pipe made of stainless steel.

[0002]

2. Description of the Related Art A conventional method for manufacturing a square pipe is shown in FIG.
As shown in Fig. 2, each of the two plate materials is bent into a U-shape in cross section, and then they are butt-joined and the butt joints are welded to produce a square pipe. A method in which the pipe is formed and then the pipe is sequentially formed into a square pipe by roll forming is used.

[0003]

The former method of the prior art inevitably requires two welding lines, which requires welding time and finishing cost of the welded portion, and deformation due to welding strain results in an accurate corner. Difficult to manufacture pipe. In addition, in order to improve the accuracy of a single piece, it is necessary to manage the single plate from the time it is needed, which is troublesome. In the case of molding from the latter round pipe, the round pipe has a limited size because it is a drawn material, and the size range is limited in order to convert it into a square pipe. Further, during roll forming, scratches are generated during forming, and particularly when producing a stainless pipe, a lot of labor is spent on finishing correction.

It is an object of the present invention to provide a method for manufacturing a square pipe which has high precision, can be manufactured economically, and has a wide range of applications.

[0005]

A method of manufacturing a square pipe according to the present invention for achieving the above object comprises the following method. Square pipe manufacturing method consisting of the following steps: (a) Pushing the widthwise central part of a plate having the required width and length with the upper and lower molds to form a large opening angle in the widthwise direction A first step of forming a V-shape with a groove, and (b) a part separated by a predetermined distance from one end of the plate material formed in the V-shape in the first step by the above-mentioned V and V
A second step of bending the member in the direction opposite to the bending direction by about 90 °, and (c) a portion separated from the end opposite to the one end of the member formed by the second step by a predetermined distance is formed in the second step. Third step of bending by approximately 90 ° with an upper die and a lower die in the same direction as the bending direction of 90 degrees, (d) One of the bending portions of approximately 90 ° in the second step and the third step, and the V shape of the first step The fourth step of bending approximately 90 ° by the upper die and the lower die in the same direction as the bending direction of approximately 90 ° between the bending part of No. 4 and (e) approximately 90 ° bending of the second step and the third step. Between the other of the parts and the V-shaped bent part in the first step, in the same direction as the bending direction in the fourth step, the upper mold and the lower mold form approximately 9
Fifth step to make a W-shaped cross-section member in which both ends are bent inward by approximately 90 degrees by bending it by 0 °, and (f) the central bending portion of the W-shaped cross-section member formed in the fifth step , The lower mold is pressed in a direction in which the bending becomes flat, and the both ends are separated from each other to form an open rectangular cross-sectional shape in the sixth step, and (g) the member molded in the sixth step is laid sideways, and the upper mold,
The seventh step of pressing by the lower mold to bring the two ends apart from each other into contact with each other to form a closed rectangular sectional shape.

[0006]

In the above method of the present invention, since there is only one welding line, the welding time and the finishing cost of the welded portion can be reduced. In addition, deformation due to welding strain is also minimized. Furthermore, by adjusting the plate width and length, it is possible to support square pipes of any cross-sectional shape, and it is possible to broaden the range of manufacturing applications.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows each step of the method for manufacturing a square pipe according to the embodiment of the present invention on the left side, and the shape of the member after each step on the right side. In the first step of FIG. 1A, a plate material having a predetermined width and length is placed on the lower mold 12. The lower mold 12 has a flat portion 12a and a recess 12b extending in the longitudinal direction.
Is formed by. The lower die 12 is fixed to a lower die holder (not shown) and is held by a bolster of a press machine. The upper die 10 has a slightly rounded tip portion, and has a shape suitable for forming a plate material into a V shape having a large opening angle in the first step (a). The upper die 10 is usually fixed to an upper die holder (not shown) and held by a ram of a press machine. In the first step, the central portion of the plate material 14 placed on the lower mold 12 is moved to the upper mold 1
By pushing with 0, a V-shaped cross-section member 14a having a large opening angle and an R at the bent portion is formed as shown on the right side of (a).

In the second step shown in (b), the member 14 formed in the V-shape having a large opening angle in the first step.
A part separated by a predetermined distance from one end of a is bent by approximately 90 ° in a direction opposite to the V-shaped bending direction by an upper die and a lower die to form a member 14b. Upper mold 16 in the second step
The tip end portion 16a of the is formed in a square shape so that the bending angle shape can be easily obtained. In the third step shown in (c), the upper mold 16 and the lower mold 12 bend a portion of the member 14b bent in the second process at a predetermined distance from the end on the opposite side to the bending side, The member 14c is formed.

In the fourth step (d), the upper die 16 and the lower die 12 are provided between one of the approximately 90 ° bent portions of the second and third steps and the V-shaped bent portion of the first step. Then, the member 14d is formed by bending it by about 90 ° in the same direction as the bending direction of about 90 ° bending in the second and third steps. In the fifth step shown in (e), between the other of the approximately 90 ° bent portions of the second and third steps and the V-shaped bent portion of the first step, the approximately 90 ° bent portion of the fourth step is bent. 9 in the direction and the circumferential direction by the upper mold 16 and the lower mold 12.
It is bent by 0 ° to form a W-shaped cross-section member 14e whose both ends are bent inward by about 90 °.

In the sixth step shown in (f), the central portion of the W-shaped cross-section member 16e formed in the fifth step is pushed by the slightly narrower upper die 18 and lower die 12 to form a square shape with opposite ends open. The cross-sectional shape member 14f is formed. In the seventh step shown in (g), the member 14f formed in the sixth step is laid sideways and pressed by the upper die 18 and the lower die 12 to form a closed rectangular cross-sectional shape by abutting the opposite ends. In the eighth step shown in (H), the butt ends of the member 14g formed into the square cross-sectional shape in the seventh step are temporarily welded by TIG welding or the like, and then main welding is performed by plasma welding or the like to finish. Modify to make a square pipe.

[0011]

According to the above method of the present invention, the following effects are obtained. I. Since there is only one welding line, it is possible to reduce man-hours by 30 to 40% in all processes such as welding time and finishing time of the welded part. B. Since the welding strain is significantly smaller than when there are two welding lines, it is possible to manufacture square pipes with good dimensional accuracy.

C. By determining the width and length of the plate,
It is possible to manufacture square pipes with a wide range of cross-sectional shapes. D. Since there are no scratches and the like compared to roll molding, the repair time can be shortened.

[Brief description of drawings]

FIG. 1 is a process drawing for carrying out a method for manufacturing a square pipe according to an embodiment of the present invention and a cross-sectional view of a member formed by each process.

FIG. 2 is a process drawing showing a conventional method for manufacturing a square pipe.

[Explanation of symbols]

 10 Upper mold 12 Lower mold 16 Upper mold 18 Upper mold

Claims (2)

(57) [Claims] 1. A method for manufacturing a square pipe, which comprises the following steps: (a) A plate having a required width and length is pushed by the upper and lower dies in the width-direction central portion to have a large opening angle in the width direction. And a first step of forming a V-shape with an R at the bent portion, (b) a V-shaped plate material in the first step, which is separated by a predetermined distance from one end of the plate material by the upper mold and the lower mold,
A second step of bending the member in the direction opposite to the bending direction by about 90 °, and (c) a portion separated from the end opposite to the one end of the member formed by the second step by a predetermined distance is formed in the second step. Third step of bending by approximately 90 ° with an upper die and a lower die in the same direction as the bending direction of 90 degrees, (d) One of the bending portions of approximately 90 ° in the second step and the third step, and the V shape of the first step The fourth step of bending approximately 90 ° by the upper die and the lower die in the same direction as the bending direction of approximately 90 ° between the bending part of No. 4 and (e) approximately 90 ° bending of the second step and the third step. Between the other of the parts and the V-shaped bent part in the first step, in the same direction as the bending direction in the fourth step, the upper mold and the lower mold form approximately 9
Fifth step to make a W-shaped cross-section member in which both ends are bent inward by approximately 90 degrees by bending it by 0 °, and (f) the central bending portion of the W-shaped cross-section member formed in the fifth step , The lower mold is pressed in a direction in which the bending becomes flat, and the both ends are separated from each other to form an open rectangular cross-sectional shape in the sixth step, and (g) the member molded in the sixth step is laid sideways, and the upper mold,
The seventh step of pressing by the lower mold to bring the two ends apart from each other into contact with each other to form a closed rectangular sectional shape. 2. The method for manufacturing a square pipe according to claim 1, wherein the butt ends having a closed rectangular cross-sectional shape are welded and assembled in the longitudinal direction of the square pipe.