JPS601088B2 - Large diameter square steel pipe manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a manufacturing apparatus for large diameter rectangular steel pipes used for construction and other purposes.

Traditionally, small-diameter square steel pipes have been manufactured by bending a single plate, but usually 35 mm x 350 mm.
In the case of large-diameter square steel pipes that are larger than legs, there are many problems in bending and other aspects, and it has been difficult to manufacture large square steel pipes from a single plate. In order to solve these problems, the present inventor previously proposed a method and apparatus for manufacturing large-diameter square steel pipes from a single steel plate, but these still have the following problems. .

In other words, a primary molded product is formed into a shape similar to a square steel pipe with each corner close to 900 by press working, and then pressed from the outside with a roller to form a square steel pipe. Even if the angle changes slightly, the levels of the joints shift significantly, and if the joints are pushed down below a predetermined level, this cannot be corrected by the outer rollers. As a result, the level of the joint becomes uneven, which hinders welding work, and the flatness of the joint surface becomes inaccurate, making it impossible to obtain a high-quality square steel pipe. In view of these points, the present invention provides an apparatus for manufacturing large square steel pipes that can accurately match the levels of joints of large square steel pipes made of a single steel plate.

That is, the present invention provides a press device that bends a single steel plate into a shape that approximates a square steel tube with each corner of approximately 90 degrees, and a press machine that presses a primary molded product that has a shape that approximates the square steel tube from the outside to form the shape of a square steel tube. In the manufacturing apparatus for large square steel pipes, which has a plurality of stages of external rolls, and a welding machine for welding butt joints in the longitudinal direction of the circumferential surface of the square steel pipe, the final stage of the external rolls has a welding machine that welds butt joints in the longitudinal direction of the circumferential surface of the square steel pipe. A core roll consisting of an upper roll supporting the inner surface of the side having the butt joint of the steel pipe, and a lower roll supporting the bottom inner surface of the steel pipe is arranged, and the upper roll and the lower roll are arranged to support the progress of the steel pipe. They are integrally connected by a connecting village with their positions shifted in the direction, and a supporting village is achieved in this connecting village, and the rear end of the supporting village is led out of the steel pipe from the joint opening □, and the lead-out part of the bracket is A large rectangular steel pipe characterized by being provided with a guide portion that holds the upper roll movable up and down and biases the upper roll in a direction to bring the upper roll into contact with the inner surface of the joint of the steel pipe using the lower roll as a fulcrum. This is the manufacturing equipment.

Embodiments of the present invention will be described below with reference to the drawings.

A steel plate 10 is pulled out from a coil of steel plate material into a material supply part, and the bend is straightened by passing it through a leveler 2. Next, the continuous steel plate 10 is cut into a predetermined length by the cutting machine 3, and while being fed in the length direction by the transfer roller 4, both sides are trimmed by the cutting machine 5. The steel plate 10 cut to a predetermined size is sent to a press 6 by a transfer roller 4, where the corners of the square steel pipe are bent by a flat press die 61 that simultaneously presses the entire length of the steel plate 10. This molding is performed first in the corner a as shown in FIG.
is bent to a predetermined angle, then corner b is bent, corner c is further bent, and corner d is bent. In this bending process, it is preferable that the angle A between the corners a and c be 9, and the angle B between the corners b and d be 1150.By this press forming, the shape approximates the square steel pipe with a cross-sectional shape as shown by the solid line in Figure 2. This primary molded product 11 is taken out from the molding press 6 by the transfer roller 4 and fed into the molding roll 7. As shown in FIGS.
1. An outer roll consisting of an upper roll 72 and coaxially rotating side rolls 73 on both sides, and a core roll consisting of a pair of upper rolls 74 and a pair of lower rolls 75 that are encased in the molded product 11 and rotate freely. It is made up of.

The lower roll 71 and the side rolls 73 are arranged in multiple stages in the length direction of the molded product 11, and the upper roll 72 is arranged at the last stage of these rolls. Moreover, the upper roll 74 is
The lower roll 75 is arranged below the upper roll 72 via the tube material and fully contacts the inner surface of the upper part (the side having the butt joint) of the T-molded product 11, and the lower roll 75 is arranged behind the upper roll 74 in the traveling direction. It is in contact with the bottom inner surface of the molded product 11. The upper roll 74 and the lower roll 75 are integrally connected by three connecting punches T6, and a support punch 77 is provided at the rear end of the central connecting village 76. The support village 77 is led out diagonally rearward from the joint closure of the molded product 11, is held at its rear end by a guide portion 78 so as to be movable up and down, and is constantly applied a downward force by a compression coil spring 79, whereby the lower roll 75 is pressed against the bottom inner surface of the molded product 11, and the upper roll 74 is pressed against the inner surface of the side of the molded product 11 having the butt-jointed portion, using the lower roll 75 as a fulcrum. By moving the support village 77 up and down along the guide portion 78, the positions of the upper and lower rolls 74, 75 can be adjusted in the vertical direction according to the size and thickness of the steel pipe. Note that as a means for applying downward force to the rear end portion of the support member 77, a hydraulic cylinder or the like may be used, or a tension spring may be used to apply the force from below. According to such a forming roll 7, the bottom roll 71 receives the bottom of the molded product 11, and the side rolls 73 press the left and right side surfaces of the molded product 11 from the outside so that the joints of the molded product 11 approach each other, thereby deforming the molded product 11 in stages. I can do it.

Then, in the final stage, the bottom of the molded product 11 is held by the lower roll 75 and the lower roll 71 from above and below, and the side of the molded product 11 having the butt joint is held between the upper roll 72 and the upper roll 74 from above and below. At the same time, it is pressed from the side with side rolls 73 to finish it into a predetermined steel pipe shape. When this primary molded product 11 is formed into a predetermined steel pipe shape using forming rolls, if it is pressed only by the outer rolls from beginning to end, the bottom part will swell outward due to the pressing force from the sides, and the left and right sides of the bottom part will expand. There was a problem in that the radii of curvature of the corners b and d tended to be larger than the set value, and the levels of the butt joints shifted and became uneven.

In particular, if the butt joint is pushed down below a predetermined level, there is no means to correct this, which will impede the welding operation. On the other hand, as in the present invention, when the bottom part is received by the bottom roll 71 and pressed from the inside by the bottom roll 75, the bottom part is constrained from both the inside and outside sides and is formed flat, and the corners on both sides of the bottom part are It is possible to prevent the radius of curvature of b and d from increasing. Further, when the side having the joint is received by the upper roll 74 and pressed from above by the upper roll 72, the joint is restrained from both the inside and outside, thereby causing the butt to come together. The side joints are not pushed down below a predetermined level, and the side planes of the butt joints can be brought into exact alignment with each other, and the radius of curvature of the corners a and c on both sides of the joint is can also be formed to a predetermined value. Therefore, it is possible to reliably obtain the flatness of each surface and the uniformity of the radius of curvature of each corner. In this manner, welding is performed by the high frequency welding machine 8 with both ends of the joint portion brought into contact with each other.

In this case, since the end surfaces of the joints match exactly, good welding can be performed and a steel pipe with excellent strength can be obtained. Moreover, according to the high frequency welding machine 8, welding is performed over the entire plate thickness, so there is no need to weld from the inner surface, and welding is completed in one step. In addition, unlike conventional submerged arc welding, etc., since no deposited metal is used, less heat is applied, reducing distortion in the product, and there is no need for processes such as beveling and tack welding. The process and equipment can be extremely simplified. Note that this welding may be performed by high-frequency induction welding or high-frequency resistance welding, and may also be conventional submerged arc welding.

The welded molded product 12 is smoothed by scraping the weld threads on the outer surface as necessary, and then sent to the strain correction device 9, where the strain is removed by a press or a roller. The straightened square steel pipe 13 passes through an ultrasonic deep flaw inspection device 20 to inspect the welded part, and then the finished product 1
They are arranged as 4. Next, other embodiments of the core roll will be described.

In FIG. 5, upper roller 84 and lower roller 85
Each of the rollers is composed of one roller, and are connected together by connecting punches 86 formed at both ends. A support village 87 is formed at the rear end of each of the connection villages 86, and the support punch 87 is bent toward the center and led out obliquely rearward from the joint opening. Further, as shown in FIG. 6, the upper roll 94 connected by the connecting punch 96 is connected to the lower roll 95.
The supporting punch 9
If the configuration is such that an upward force is applied to the roller 7, the upper roller 94 will be pressed against the inner surface of the twill with the lower roller 95 as a fulcrum. As explained above, this invention
In equipment that manufactures large diameter rectangular steel pipes with only one weld tangent line from a single sheet steel plate, by adopting a core roll consisting of an upper roll and a lower roll, the flatness of each surface of the steel pipe and the radius of curvature of each corner are improved. It is possible to accurately obtain the uniformity and properties of steel pipes, and it is also possible to weld the side end surfaces of the butt joints of steel pipes to exactly match each other, and to perform good welding with excellent strength. This has the advantage that it is possible to

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus according to the present invention, FIG. 2 is a cross-sectional view of a flat steel pipe in a state of bending, FIG. 3 is a vertical cross-sectional side view showing the appearance of the present invention, and FIG. FIG. 5 is a perspective view showing another embodiment of the main part, and FIG. 6 is a perspective view showing still another embodiment of the main part. 6... Forming press, 7... Forming roll, 8... Welding machine, 10... Single steel plate, 7
1, 72, 73...Outer roll, 74, 84,
94... Upper roll, 75, 85, 95...
...lower roll, 76, 86, 96...connected punch,
T7, 87, 97... Support village, 78... Guide department. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1 A press machine that bends a single sheet steel plate into a shape that approximates a square steel pipe with each corner of 90° or more, and a multi-stage press that presses the primary molded product in a shape that approximates the square steel pipe from the outside to form a square steel pipe. In a large-diameter square steel pipe manufacturing apparatus that has an outer roll and a welding machine for welding joints of square steel pipes, the final stage of the outer rolls includes an upper roll that contacts the inner surface of the joint of the steel pipe, and an upper roll that contacts the inner surface of the bottom part of the steel pipe. A core roll consisting of a lower roll that comes into contact with the upper roll is arranged, and the upper roll and the lower roll are integrally connected by a connecting rod with their positions shifted in the traveling direction of the steel pipe, and a branch rod is attached to this connecting rod. is achieved, the rear end of the support rod is led out from the joint opening to the outside of the steel pipe, and while this lead-out part is held movable up and down, the upper roll is brought into contact with the inner surface of the joint of the steel pipe using the lower roll as a fulcrum. 1. An apparatus for manufacturing a large diameter rectangular steel pipe, characterized in that it is provided with a guide section that urges the pipe in the direction of contact.