JPH0228436B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a welding device for square steel pipes, and more specifically, a push-down roll that presses a square steel pipe sandwiched between horizontal pressing dies from above, and a welding device for welding a square steel pipe. By collaborating with push-up rolls placed inside, it forms welded parts of square steel pipes and continuously welds those welded parts, making it possible to manufacture long electric resistance welded pipes. This relates to welding equipment.

[Conventional technology]

In order to bend a flat plate and weld it into a steel pipe, the two end faces are usually brought together and the welded parts are high-frequency welded. FIG. 4 shows the arrangement of pressing dies in a welding device used when manufacturing the round steel pipe 30. For this purpose, horizontal pressing dies 31, 31 are provided on the outside of the round steel pipe 30 to press it from the left and right sides, a supporting roll 32 is arranged on the lower side, and a support roll 32 is placed above the opening 33 to be welded. Presser rolls 34, 34 are provided.

Then, these press molds 31 and rolls 32, 34
ERW tube material (column) 30 formed by
After passing through the press die 31 and rolls 32 and 34, the contact 1 of the power supply electrode facing the welding area 4
Welded by 8.

[Problem to be solved by the invention]

By the way, even if a round steel pipe can be manufactured using the above-mentioned apparatus, it is difficult to apply it to welding a square steel pipe. That is, during the forming process in which the flat plate is pressed by each press to transform it into a square shape, a buckling phenomenon occurs in the surface portion, and as a result, a square steel pipe of the desired shape cannot be obtained. This is because squaring causes a change in direction by bending each side of the square, and in the device configured as above, the suppression is in one direction from the outside to the inside, and there is no way that it can be normal. It is not possible to obtain a rectangular steel pipe.

For example, when manufacturing a rectangular steel pipe 1 shown in FIG.
b curves downward and upward as shown in FIGS. 6 and 7. As a result, although pressure is applied to correct the misalignment between the upper surfaces 1a and 1b, it becomes difficult to weld the welding portion 4. In other words, when a lateral pushing force is applied to the upper surfaces 1a and 1b, the upper surfaces 1a and 1b bend, and buckling occurs when a lateral pushing force of a certain value or more is applied depending on the slenderness ratio (L/2t) of the upper surface. occurs. Note that the shape of the square steel pipe 1 will be corrected in the post-process, but if the above deformation is large at the time of welding, the shape of the square steel pipe 1 will be corrected.
This will greatly reduce the product value of the product.

By the way, as shown in FIG. 5, it is possible to generate an upset force by wrapping the square steel pipe 1 from three or four sides with press molds 31, 31, etc. shown by two-dot chain lines, and applying a tangential force to the outer periphery. It is known. However, in the case of square steel pipes, there is a problem that sufficient upsetting force cannot be obtained. That is, in high-frequency welding, in order to generate the necessary upset force at the welding part 4, it is necessary to stop buckling when the value obtained by dividing the length L/2 of the upper surfaces 1a and 1b by the plate thickness t becomes large. , it is necessary to buckle it outward and use a presser roll from above to adjust it so that it buckles outward. However, in conventional devices, no consideration has been given to making such a possibility possible.

In addition to the example shown in FIG. 5, for example, instead of the left and right lateral presses 31, 31, a device may be considered in which rolls extending to the ends of the upper and lower surfaces of the square steel pipe 1 are arranged on the left and right sides, but in this case, the above-mentioned Unable to control buckling phenomenon. That is, as shown in Fig. 8, the left and right upper surfaces 1
A misaligned portion 3 is generated between a and 1b. If such a misaligned portion 3 exists, an incomplete welded portion will occur during automatic continuous welding, resulting in a steel pipe with defects.

Moreover, with respect to the presser roll 34 shown in FIG.
If there is no support means to receive the force from below, the square steel pipe 1
In this case, as shown by the broken line in FIG. 5, there was a risk that the welded part 4 would collapse and lose its shape, resulting in a defective product.

The present invention was made in view of the above-mentioned problems, and its purpose is to eliminate the effects of buckling on the upper surface of the welding area in the work process of welding while applying pressure as described above, thereby achieving good welding. was done,
It is an object of the present invention to provide a welding device capable of obtaining inexpensive and high-quality electric resistance welded pipes and rectangular steel pipes.

[Means to solve the problem]

The present invention includes horizontal pushing dies arranged on the left and right sides of a square steel pipe that can move forward and backward, and a pair of left and right pushing rolls that move up and down above the square steel pipe in order to press the vicinity of the welding part of the square steel pipe. It is applied to a welding device that manufactures a rectangular electric resistance welded steel pipe by forming a rectangular steel pipe while deforming it and continuously welding the welded parts.

Its characteristic feature is that, with reference to FIG. 1 and FIG. , 1b are provided from below.
The center 17A of each of the push-up rolls 17, 17 in the width direction is the center 6 of each of the push-down rolls 6, 6 in the width direction that faces each push-up roll 17, 17.
With respect to A, they are arranged to be shifted outward in the left-right direction of the square steel pipe 1, respectively. A power supply electrode 18 to which a high frequency current for welding the welding portion 4 is applied is installed downstream of the push-down rolls 6, 6 in the direction of movement of the rectangular steel pipe 1.

〔Effect of the invention〕

According to the present invention, the planar plate is continuously formed into a square shape,
On the upper surface where the welding part of the free end is located, the discrepancy in the horizontal plane is corrected so as to be suitable for high frequency welding, and a good condition for welding can be achieved. On the other hand, the center of the push-up roll in the width direction is shifted outward by a certain distance in the left-right direction of the square steel pipe with respect to the center of the roll of the push-down roll in the width direction, so that it corresponds to the top and bottom. A force is also applied to the upper surface to bend it downward at each end, eliminating the step at the welding area. Therefore, buckling can be suppressed by the roll action and the lateral pressing die, and the manufacturing accuracy of the dimensions and shape of the product can be improved. In this way, high-frequency induction welding can be performed while maintaining a rectangular steel pipe manufactured to a finite length and subject to significant stress changes in a stable state suitable for welding.

〔Example〕

The present invention will be described in detail below based on examples thereof. FIG. 3 is a sectional view of the square steel pipe 1 which has been formed into a substantially square shape before welding, and the formed product is about to be transformed into the final shape for welding. 1 in the figure is a rectangular steel pipe to be welded, and its upper surfaces 1a and 1b are opposite to each other with a gap 2 in between.This device, as shown in FIG. , 1b, it is possible to perform uniform and high-quality welding by suppressing warpage without producing a misaligned portion 3.

To explain the entire welding apparatus, as shown in FIG. 1, a pushing means 5 for pushing down a welding part 4 is installed. This is used as one of the means for keeping the ends of the upper surfaces 1a and 1b close to each other as shown in FIG. 5 in the rectangular steel pipe 1 which is an electric resistance welded pipe. That is, the push-down rolls 6, 6 are pivotally connected to the lower end of the frame 7,
A frame 7 is installed on a fixed machine frame (see Fig. 2) so as to be movable up and down by fluid pressure, etc., and as it descends toward the welding area 4, it pushes down the upper surfaces 1a and 1b and rises to form a mountain shape. It functions to flatten the welding area 4.

On the other hand, as shown in FIG. 3, horizontal pressing means 9 is provided. This is on the side of the square steel pipe 1,
Pressing surface 11a, by cylinder mechanism 10,10
Reference numeral 12a denotes horizontal pressing dies 11 and 12 that are moved laterally and press the square steel pipe 1 from the side. By this horizontal pressing means 9 and the pressing means 5 described above, the welding area 4 (see FIG. 5) is properly shaped. That is, by pressing the roughly formed square steel pipe 1 from the left and right sides, the dimensions in the left and right direction of the square steel pipe 1 are adjusted to specifications, and both side surfaces 13a,
13b is suppressed from buckling.

In addition to the above, core means 14 are provided and function as an interpolation roll device. Two pairs of front and rear guide wheels 15, 15 are provided at the bottom of this core means 14,
It is installed so as to be movable back and forth in the traveling direction of the square steel pipe 1 (the left-right direction in FIG. 2) by means of guide rods 16, 16.
The movement may be carried out by hydraulic, electric, manual, etc. Push-up rolls 17, 17 are pivotally supported on this core means 14, and the upper surfaces thereof are set at a height that coincides with the lower surfaces of the upper surfaces 1a, 1b of the square steel pipe 1 at their normal positions.

By the way, the center 17A of each of the push-up rolls 17, 17 in the width direction, and the center 6A of the push-down rolls 6, 6 facing it in the width direction of each roll,
They are arranged outwardly shifted by a distance α in the left-right direction of the square steel pipe 1, respectively. As a result, the misalignment in the horizontal planes as shown in FIG. 8 is corrected, and the upper surfaces 1a and 1b are pressed up and down so as to suppress buckling of the upper surfaces 1a and 1b. The square steel pipe 1 advances in a direction perpendicular to the plane of the paper while being drawn out by a moving means (not shown) and being high-frequency welded at the welding portions 4 at the ends of both upper surfaces 1a and 1b.

The rectangular steel pipe 1 is welded by the welding means in a state where the welding area 4 is suitable by the above three means 5, 9, and 14, but for this purpose, as shown in FIG. A contact 18 is installed, which is held by a support 19.

In such a configuration, the square steel pipe 1 roughly shaped as shown in FIG. 3 is fed from the right side to the left side in FIG.
6. When the position of the horizontal pressing molds 11 and 12 of the horizontal pressing mold means 9 is reached, the welding part 4 is pressed down as shown in FIG. At that time, the push-up rolls 17, 17
The acting force is absorbed so that the product does not become deformed due to being pushed down excessively by the contactor 18 disposed on the downstream side.

In the case of the rectangular steel pipe 1, as mentioned in the section on the prior art, sufficient upset force cannot be obtained, but in order to generate the necessary upset force at the welding area 4 during high frequency welding, the length of the welding surface must be adjusted. When L/2t, which is calculated by dividing L/2 by plate thickness t, becomes large, buckling is stopped or buckling is caused to occur outwards and the rolls 6, 6 are pressed down from above.
Adjust so that it buckles to the outer bulge. These are the push-down rolls 6, 6 and push-up roll 1 described above.
By providing an offset amount .alpha. with respect to 7 and 17, this problem can be eliminated. In this way, by shifting the centers 6A and 17A of the facing rolls, bending forces as indicated by arrows 21 and 22 in the figure (see Figure 3) are easily applied to the ends of the upper surfaces 1a and 1b. This makes it easy to correct the misaligned portion 3 (see FIG. 8). After being formed into such a state, the square steel pipe 1 is transferred, and its welding portion 4 is welded with a high frequency current from the power supply electrode 18.

Square steel pipe 1 which is as described above and is continuously formed into a square shape from a flat plate and welded at the welding part 4 at the free end.
The top surfaces 1a and 1b, which are most important and difficult to adjust in the high-frequency processing and manufacturing apparatus, can be brought into the best condition. That is, the push-up rolls 17, 17 and the push-down rolls 6, 6 correspond to each other to correct the discrepancy in the horizontal plane to be suitable for high-frequency welding, and by making the welding part 4 face upward, it is possible to improve the pressure welding process. This has the advantage that the welding residue is always pushed out to the outside and there is no need to remove it.

On the other hand, the center 17A of the push-up rolls 17, 17 in the width direction corresponds to the center 6A of the push-down rolls 6, 6 in the width direction, respectively, by a distance α in the left-right direction of the square steel pipe 1. As mentioned above, the upper surfaces 1a and 1b are bent downward at their ends, thereby eliminating the step at the welding area 4. . Furthermore, buckling can be suppressed by these roll actions and horizontal pressing,
It is possible to improve the manufacturing accuracy of product dimensions and shapes.

In this way, by providing a pair of push-up rolls 17, 17 inside the rectangular steel pipe 1, which is an ERW pipe, they work together with a pair of push-down rolls 6, 6 to prevent the welding area 4 from falling (see Fig. 5). (see dashed line inside).
A finished shape with regular dimensions can be obtained.

As can be seen from the above description, in the present invention, high-frequency induction welding can be performed while maintaining a stable state suitable for welding on an ERW tube material (column) manufactured to a finite length and subject to significant stress changes. .

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a square steel pipe being formed into a regular shape, Figure 2 is a view taken along the - line in Figure 1,
Fig. 3 is a cross-sectional view of a roughly formed square steel pipe when it reaches this device, Fig. 4 is a cross-sectional view of a conventional technique when pressure welding a round steel pipe, and Fig. 5 is a cross-sectional view of a square steel pipe. , FIG. 6 and FIG. 7 are cross-sectional views of an example in which the upper surface of the square steel pipe is buckled, and FIG. 8 is a cross-sectional view of the square steel pipe showing a dislocated portion. 1...Square steel pipe, 1a, 1b...Top surface, 4...
Welding part, 6...Press roll, 6A...Center,
11, 12...Horizontal push type, 17...Push roll,
17A... Center, 18... Power supply electrode (contact).

Claims (1)

[Scope of Claims] 1. Includes horizontal pushing dies arranged on the left and right sides of the square steel pipe that can move forward and backward, and a pair of left and right push-down rolls that move up and down above the square steel pipe in order to press the vicinity of the welding part of the square steel pipe. , in a welding device that manufactures a square ERW steel pipe by forming a square steel pipe while deforming a flat plate and continuously welding the welded parts, the above-mentioned pair of A pair of push-up rolls are provided that face the push-down rolls and support the upper surface of the square steel pipe from below, and the centers of the respective push-up rolls in the width direction face each of the push-down rolls. A high-frequency current is applied to the downstream side of the push-down roll in the movement direction of the square steel pipe for welding the welding part. A welding device for rectangular steel pipes, characterized in that a power feeding electrode is installed therein.