JP2000312918A - Square shape steel pipe molding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily perform carrying-in and carrying-out of an approximately square shape steel pipe against a molding device part. SOLUTION: This first step molding device part 31 comprises; a supporting means 33 for supporting, guiding an approximately square shape steel pipe 8, a movable inner die 41 and a movable outer die 51 which can clamp from inside and outside an intermediate plain plate part 5 of the approximately square shape steel pipe 8 being released from a support of the supporting means 33, and a side part pressing means 61 which bend molds a pair of side plain plate parts 6 inwardly so as to become closer to right angle. The last step molding device comprises left and right rolls, upper and bottom rolls for molding both obtuse angle bent parts 4A to a right angle shape bent part by pressurizing the side plain plate part 6 inwardly. Thus, the approximately square steel pipe 8 can be easily and rapidly carried in the first step molding part 31 by support guiding of the supporting means 33. Also, the steel pipe 8 can be easily and rapidly conveyed from the first step molding part 31 to the last step molding part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for obtaining a large-diameter and thick-walled (for example, a very thick wall of 32 mm or more) rectangular steel pipe having a rectangular shape or a rectangular parallelepiped shape used for, for example, pillars for construction. The present invention relates to a square steel pipe forming apparatus to be formed.

[0002]

2. Description of the Related Art Conventionally, square steel pipes have been manufactured as follows. That is, JP-A-10-25831
As can be seen in Japanese Patent Publication No. 3 (1994), first, two portions near the groove-equivalent portion in the width direction of the steel plate are bent at right angles, and two portions inside the right bent portion are bent at an obtuse angle to approximate. Form a square steel pipe. Next, the approximate square-shaped steel pipe is put into the pre-forming apparatus, and the intermediate flat portion between the obtuse bent portions is clamped by the fixed outer mold and the inner mold that can be freely moved toward and away from the outer mold. A pair of pressing dies presses a pair of side flat portions connected to the intermediate flat portion inward, and bends both obtuse bent portions so as to approach a right angle.

[0003] Then, the approximate square-shaped steel pipe is transferred from the former-stage forming apparatus to the latter-stage forming apparatus. In this latter molding device,
The roll group presses the pair of side plate portions inward to form both obtuse bent portions into right-angled bent portions, and forms one butt portion with the right and left groove equivalent portions. Welded. According to such a conventional configuration, an approximate square steel pipe having a long opening portion between the groove-corresponding portions where the four portions are bent has a short opening length between the groove-corresponding portions by pre-bending in the pre-forming apparatus. And both obtuse bent portions can be at an angle close to the product bending angle. At this time, the pre-stage bending can be performed while maintaining the flat shape of the intermediate flat plate portion and approaching a bending radius similar to the bending radius of the right-angled bent portion.

[0004]

However, according to the above-mentioned conventional construction, the intermediate flat plate portion of the approximately square steel pipe is sandwiched between the fixed outer die and the movable inner die, so that the fixed outer die is fixed. It is not easy to carry in a long approximate square-shaped steel pipe to a mold or to carry out an approximate square steel pipe from a fixed outer mold. As a result, efficient molding cannot be performed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a square steel pipe forming apparatus capable of easily carrying in and out an approximate square steel pipe to and from a forming apparatus.

[0006]

In order to achieve the above-mentioned object, in the present invention, the apparatus for forming a square-shaped steel pipe according to the first aspect of the present invention comprises: Is formed into a square steel pipe by bending an approximate square steel pipe obtained by bending two portions inside the right-angled bent portion at an obtuse angle, and forming a pre-stage forming unit and a post-stage forming unit. The front-stage forming device section comprises a support means for supporting and guiding the approximate square steel pipe in the longitudinal direction with the opening thereof facing upward, and an obtuse angle bent part in the approximate square steel pipe released from the support by the support means. A movable inner mold and a movable outer mold capable of holding the intermediate flat plate portion from inside and outside, and a pair of side flat plate portions connected to the intermediate flat plate portion held by the movable inner die and the movable outer die are bent inward so as to approach a right angle. Molding The left and right rolls and the upper and lower rolls are configured to press the pair of side plate portions inward to form both obtuse angle bent portions into right angle bent portions. This is characterized by the configuration described above.

Therefore, according to the first aspect of the present invention, an approximately square steel pipe having a long opening portion between the corresponding portions of the groove formed by bending the four portions is formed into a pre-forming device section by the lengthwise supporting guide by the supporting means. Then, the intermediate flat plate is sandwiched between the movable inner die and the movable outer die, and the side flat plate is bent inward so as to approach a right angle by the side pressing unit while the support by the support unit is released. Thus, the former-stage bending device can perform the former-stage bending forming. By this pre-bending, the approximate square-shaped steel pipe can have a short opening length between portions corresponding to the groove, and can make both obtuse bent portions close to the product bending angle. Then, the approximate square steel pipe can be transported from the former-stage forming device to the latter-stage forming device by the support and guide by the supporting means.

[0008] Thereafter, the approximate square-shaped steel pipe can be subjected to the second-stage bending forming in the second-stage forming device so that the both obtuse-angle bent portions become right-angled bent portions. At that time, it is necessary to bend the obtuse bent part into a right-angled bent part to eliminate the opening,
Since the opening length is short, it can be easily performed with a light pressing force. Thereafter, by performing welding while applying pressure from the outside, a large-diameter and thick-walled square steel pipe (product) can be manufactured.

According to a second aspect of the present invention, there is provided an apparatus for forming a square steel pipe according to the first aspect.
The support means is composed of a group of rollers, and is configured to be switchable between a support guide position and a support release position for the approximate square steel pipe by moving the roller group in the roller axis direction. Therefore, according to the second aspect of the invention, the support and guide of the approximately square steel pipe can be easily and smoothly performed by the roller group.

According to a third aspect of the present invention, there is provided an apparatus for forming a square steel pipe according to the first or second aspect, wherein the side pressing means comprises a pair of left and right side pressing dies;
It is characterized by comprising a mold left-right moving device for moving these side pressing dies left and right. Therefore, according to the third aspect of the present invention, the pair of left and right side pressing dies are moved left and right by the mold left and right movement device, so that the inside of the side plate portion can be reliably and smoothly bent.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. First, an example of manufacturing the approximate square steel pipe 8 will be described with reference to FIGS. That is,
The strip-shaped steel sheet 1 having a thickness of 12 to 40 mm shown in FIG. 7 transports the strip steel sheet in the length direction, passes through a trimming beveling machine, and processes the groove 2 on both side edges in the width direction W. To a predetermined length. Then, as shown in FIGS. 8 and 9, the steel sheet 1 is put into the former forming press device 20,
As the upper mold 22 moves up and down with respect to the lower mold 21, two places near the groove 2 in the width direction W are bent at a right angle (90 degrees or almost 90 degrees) to form a right angle bent portion (corner). Form 3

Next, as shown in FIG. 10 and FIG. 11, the steel sheet 1 is put into a forming press device
Of the right-angled bent part 3
Are bent at an obtuse angle (about 105 degrees) to form an obtuse bent portion 4A. Thereby, the obtuse bent part 4
A portion between A is an intermediate flat plate portion 5, a portion connected to the intermediate flat plate portion 5 is a pair of side flat plate portions 6, an outer end portion of the right-angled bent portion 3 is an end flat plate portion 7, and a long opening portion between the grooves 1 An approximate square steel pipe 8 of L is formed.

[0013] In this manner, the subsequent molding press 2
As shown in FIGS. 1 to 3, the approximate square steel pipe 8 having a long opening length L formed by the step 3 is put into a forming apparatus 30 for forming the square steel pipe via a transfer table 28 in the form of a drive roller. . Here, the molding device 30 is configured by a former molding device portion 31 and a latter molding device portion 71. That is, the pre-stage forming device section 31 has a common frame 32, and the supporting means 3 for supporting and guiding the approximate square steel pipe 8 in the longitudinal direction with the opening thereof facing upward.
3 and an intermediate flat plate portion 5 between the obtuse bent portions 4A of the approximate square steel pipe 8 released from the support by the support means 33.
Inner mold 41 and movable outer mold 5 that can clamp
1 and side pressing means 61 for bending a pair of side flat plates 6 connected to the intermediate flat plate 5 sandwiched by the movable inner die 41 and the movable outer die 51 inward so as to approach a right angle. It is constituted by doing.

The support means 33 has a group of rollers 34,
By moving the roller in the axial direction of the roller, the support guide position (inwardly protruding position) and the support release position (outward retreat position) for the approximate square steel pipe 8 can be switched. That is, the roller group 34 is divided into left and right groups,
A plurality is provided in the direction of the forming movement path A, with the roller axis direction being the left-right direction. Each roller 34 is inserted into a holding device 35 provided on the side of the frame 32 and is guided so as to be movable and rotatable in the roller axis direction, and the movement is performed by the outer end of the roller 34 and the frame 32. It is configured to be performed by a cylinder device 36 provided between the side.

The holding device 35 rotatably supports the passive tooth wheel 37 on the outer end side thereof, and the roller 34 is configured to be movable in the axial direction of the roller relative to the passive tooth wheel 37 in a rotationally transmitted state. Is done. Passive tooth wheel 37 adjacent before and after
The group is hung with a chain 38 and the chain 38
Is also hung on the drive tooth wheel 40 of the rotary drive device 39 provided on the frame 32 side.

The movable inner die (upper die) 41 is provided so as to be movable up and down. That is, a movable frame 43 is provided, which can be moved up and down by being guided by the vertical guide body 42 on the side of the frame 32. The movable frame 43 can be moved up and down by the operation of a lifting cylinder device 44 provided between the movable frame 43 and the frame 32. , And the lower limit thereof is maintained by the stopper 45. Here, a plurality (or singular) of the lifting / lowering cylinder devices 44 are provided in the direction of the forming movement path A, and a lifting / lowering guide device (comprising a cylindrical guide or a rod) is provided at a required position.

The movable inner mold 41 is elongated along the direction of the forming movement path A, and is connected to a group of operating bodies 46 vertically provided from the movable frame 43 by connecting members (such as bolts).
It is attached via a connector 47, and is configured to be compatible with various sizes by being replaced by operating the connector 47. The movable outer die (lower die) 51
Are provided such that the intermediate flat plate portion 5 between the obtuse-angle bent portions 4A can be placed thereon and can be moved up and down. That is, the movable outer mold 51 is elongated along the direction of the forming movement path A, and is configured to be able to move up and down by the operation of the upwardly moving cylinder device 52 provided on the frame 32 side.
Here, a plurality (or singular) of the lifting / lowering cylinder devices 52 are provided in the direction of the forming movement path A, and a lifting / lowering guide device (comprising a cylindrical guide or a rod) 53 is provided at a plurality of locations.
Is provided.

Here, the width of the movable outer mold 51 in the left-right direction is
The rollers 34 are set so as to be able to correspond to various sizes and to be able to move up and down between the left and right free ends of the group of rollers 34 switched to the support release position (outside retreat position). There is provided a receiving base 54 which can penetrate below the movable outer mold 51, and the receiving base 54 is a pair of right and left.
5 is configured to perform entry and exit.

The side pressing means 61 is composed of a pair of left and right side pressing dies 62 and a die left and right moving device 66 for moving the side pressing dies 62 left and right. That is, a pair of left and right mold holding frames 63 are provided, and these mold holding frames 63 are elongated along the direction of the forming movement path A, and are attached to the guide rod 64 from the frame 32 side by the cylindrical guide body 65. Is supported and guided via the.

Here, the guide rods 64 are protruded inward in the left-right direction from a plurality of locations in the direction of the forming movement path A, and are provided between the lower portions of the group of cylindrical guide bodies 65 supported and guided by these guide rods 64. The mold holding frame 63 is connected. The side pressing die 62 is attached to the inner surface of the mold holding frame 63. Here, the inner surface of the side pressing die 62 has a lower half vertical pressing surface 62a and an upper half inclined pressing. It is formed by the surface 62b.

The mold left-right movement device 66 is composed of a group of left and right cylinder devices 67 with their piston rods directed inward, and the outer surface of the mold holding frame 63 is connected between the free ends of the piston rods. It is to be noted that the protruding limit of the group of cylinder devices 67, that is, the side portion pressing limit, is configured to be regulated by an adjustable stopper 68. The rear-stage forming unit 71 arranged below the pre-stage forming unit 31 configured as described above presses the pair of side plate portions 6 inward to form the obtuse bent portions 4A into right-angle bent portions (corner portions). )
4 is formed. That is, the rear-stage forming unit 71 is a roll forming unit, and the right and left rolls 7 are used.
It is configured by arranging a single set (or a plurality of sets) of the set composed of 2 and the upper and lower rolls 73 in the transport direction with respect to the frame 74 side.

An elevating feed roller 76 is disposed between the former molding device 31 and the latter molding device 71, and a roller type elevating type lower roller is provided below the latter molding device 71. Transfer table 78 and tack welding means 8
1 and a roller-type unloading table 88 are arranged in this order. The tack welding means 81 includes left and right rolls 82, upper and lower rolls 83, a tack welder 84, and the like.

The operation of forming the approximate square steel pipe 8 formed by the subsequent forming press device 23 into a square steel pipe in the forming device 30 will be described below. That is, in the molding apparatus 30, as shown by the solid line in FIG.
The movable inner die 41 is brought to the intermediate position by the operation of the lifting / lowering cylinder device 44, and the movable outer die 51 is brought to the lowering position by the operation of the lifting / lowering cylinder device 52. The side pressing die 62 of the pressure means 61 is moved backward by the operation of the die left / right moving device 66.

In such a state, the approximate square steel pipe 8 from the subsequent forming press device 23 is conveyed on the forming moving path A via the driven conveying table 28 and the like. Here, the group of rollers 34 of the support means 33 is also driven and rotated via the rotary drive device 39 and the like, so that the approximate square steel pipe 8 is conveyed while the intermediate flat plate portion 5 is supported by the group of rollers 34. You. At that time, the approximate square steel pipe 8 is fitted to the movable inner die 41 at the intermediate position with the operating body 46 positioned at the opening.

When it is detected that the approximate square steel pipe 8 has been carried in to a predetermined amount (a position where the front end does not protrude from the preforming device 31), the conveyance by the conveyance table 28 and the support means 33 is stopped. Let it. Next, as shown in FIG. 4B, the movable inner die 41 is set to the ascending limit position by the contraction operation of the lifting / lowering cylinder device 44, and the approximate square steel pipe 8 is raised through the movable inner die 41. To release the support by the group of rollers 34.

Then, as shown in FIG. 4 (c), the roller group 34 is retracted to the support release position by the contraction movement of the cylinder device 36. Then, the lifting cylinder device 5
In a state where the movable outer mold 51 is at the ascending limit position by the extension movement of the movable outer mold 51, the movable outer mold 51 is
The cradle 54 protrudes below. Next, the movable outer mold 51 is lowered by the contraction movement of the lifting / lowering cylinder device 52 and mounted on the receiving table 54, and the movable outer mold 51 is fixed at a predetermined level position. Then, the movable inner die 41 is lowered by the extension operation of the lifting / lowering cylinder device 44,
The approximate square steel pipe 8 is lowered via the movable inner die 41.

Thus, as shown in FIG. 1 and FIG. 2, the approximate square steel pipe 8 is placed on the movable outer die 51 via the intermediate flat plate portion 5, and the movable inner die is placed on the inner surface of the intermediate flat plate portion 5. The mold 41 is brought into contact, and the intermediate flat plate portion 5 is sandwiched between the movable outer mold 51 and the movable inner mold 41 from inside and outside with a small force. In the state where such holding is maintained, the side pressing die 62 of the side pressing means 61 is moved forward by the operation of the die left / right moving device 66, and the inclined pressing surface 62b is pressed against the side flat plate portion 6 from outside. By contacting, the approximate square steel pipe 8 is centered in the left-right direction. Thereafter, the movable inner die 41 and the movable outer die 51
As a result, the intermediate flat plate portion 5 is clamped from inside and outside with a desired force. The center pressing in the left-right direction by the side pressing means 61 may be performed in a state where the intermediate flat plate portion 5 is sandwiched from inside and outside by a predetermined force.

In the state where the intermediate flat plate portion 5 of the approximate square steel pipe 8 is sandwiched between the movable outer die 51 and the movable inner die 41, the mold left-right movement device 66 of the side pressing means 61 is operated. By moving the pair of side pressing dies 62 forward, the side plate 6
Is pressed inward, and as shown in FIG. 4 (d), the two obtuse bent portions 4A are bent so as to approach a right angle.
This bending is performed until the groove 2 is sufficiently close to (or lightly abuts) the working body 46, so that the gap between the grooves 2 can be made a short opening length l, and both obtuse bent portions 4 can be formed.
A is pre-bent-formed at an angle close to the product bending angle.

The approximate square steel pipe 8 thus formed in the former-stage forming unit 31 is transferred to the latter-stage forming unit 71 shown in FIG. That is, as shown by the imaginary line in FIG. 4A, the approximate square steel pipe 8 formed to have a short opening length l by the reverse action or almost reverse action to the support means 33, the feed roller 76, and the like. Is sent to the second-stage molding device section 71 via.

Then, as shown in FIG. 5, the pair of side plate portions 6 is pressed inward by the rolls 72 in the post-forming device 71 while feeding the approximate square steel tube 8 in the longitudinal direction. At the same time, by pressing and regulating the intermediate flat plate portion 5 and the end flat plate portion 7 inward by the rolls 73, both obtuse bent portions 4A are bent at right angles (corners).
While bend-forming into 4, post-bend forming can be performed by abutting the grooves 2 to form a square steel pipe 9.

At this time, it is easy to bend the obtuse bent portion 4A into the right-angled bent portion 4 to eliminate the opening with a small pressing force because of the short opening length l. Therefore, the bending of the obtuse bent portion 4A into the right-angled bent portion 4 can be performed at the same bending radius R as that of the right-angled bent portion 3 without impairing the flat shape of the intermediate flat plate portion 5. . That is, each of the right-angled bent portions 3 and 4
Its size and shape can be made uniform.

Subsequently, the square steel pipe 9 is transferred to a tack welding means 81 via a transfer table 78 or the like.
In the state where the intermediate flat plate portion 5 and the end flat plate portion 7 are pressed inward by the rolls 83 and regulated while being pressed inward by the second group, the abutting portions of the grooves 2 are
As shown by a solid line, the tack welding 10 is performed by the tack welding machine 84.

Thereafter, the square steel pipe 9 is transferred to an inner surface welding machine (not shown) to perform inner surface welding, and then transferred to an outer surface welding machine (not shown) to perform outer surface welding. As shown by the imaginary line in FIG. 6, a large-diameter, thick-walled square steel pipe (product) 12 having a butt weld (seam weld) 11 on the end plate (one side) can be manufactured. As a result, the rectangular steel pipe 12 does not have the flat plate portions 5, 6, and 7 in a wavy shape or a curved shape, and the shape of the bending radius R as well as the bending radius R of each of the right-angled bent portions 3 and 4. Will also be equalized, and the quality will be better.

In the above-described embodiment, the forming by the former-stage forming unit 31 may be performed in such a manner that the entire length of the approximate square steel pipe 8 is made once, or the approximate square steel pipe 8 may be formed in the longitudinal direction. The molding may be performed a plurality of times while intermittently transporting. In the above-described embodiment, the roll type is adopted as the post-stage forming device 71, but this may be a press type provided with a pressing die.

In the above-described embodiment, a large-diameter, thick-walled rectangular steel pipe (product) 12 having a butt weld (seam weld) 11 on one side is manufactured. It may be a steel pipe, a small-diameter thick-walled square steel pipe, a small-diameter thin-walled square steel pipe, or the like.

[0036]

According to the first aspect of the present invention, the approximate square steel pipe having a long opening between the corresponding portions of the groove which is bent at four locations is guided by the supporting means in the longitudinal direction by the supporting means. The side plate portion can be easily and quickly carried into the molding device portion, and the side plate portion is held by the side pressing device while the intermediate plate portion is held between the movable inner die and the movable outer die and the support by the support means is released. By bending inward so as to approach a right angle, front-stage bending can be performed in the front-stage forming device. By this pre-bending, the approximate square-shaped steel pipe can have a short opening length between the portions corresponding to the groove, and both obtuse bent portions can have an angle close to the product bending angle. Then, the approximate square-shaped steel pipe can be easily and quickly conveyed from the former-stage forming device to the latter-stage forming device by the support and guidance by the supporting means.

Thereafter, the approximate square-shaped steel pipe can be formed in the latter-stage bending in the latter-stage forming device so that both obtuse-angled bent portions become right-angled bent portions. Eliminating the opening by bending into an opening can be easily performed with a small pressing force because of the short opening length. Therefore, the apparatus main body of the post-forming apparatus does not require large rigidity, and can be a compact and inexpensive investment equipment, and can reduce the cost of the product. The device can be developed even in the case of a thick wall.

According to the second aspect of the present invention,
The support and guide of the approximately square steel pipe can be easily and smoothly performed by the roller group. According to the third aspect of the present invention described above, the pair of left and right side pressing dies are moved left and right by the mold left and right movement device, whereby the inside of the side plate portion can always be reliably and smoothly bent. it can.

[Brief description of the drawings]

FIG. 1 shows an example of an embodiment of the present invention, and is a longitudinal sectional front view of a side pressing means portion of a former-stage forming device in a forming device of a square steel pipe.

FIG. 2 is a vertical sectional front view of a support means portion of a former-stage forming device in the forming device for forming the square steel pipe.

FIG. 3 is a partially cutaway plan view of the square steel pipe forming apparatus.

FIG. 4 is a front view of a main part for explaining a forming state of the square steel pipe forming apparatus.

FIG. 5 is a schematic front view of a second-stage forming unit in the forming unit for forming the square steel pipe.

FIG. 6 is a schematic front view of a tack welding means in the rectangular steel pipe forming apparatus.

FIG. 7 is a front view of a steel plate in the method for manufacturing the square steel pipe.

FIG. 8 is a front view of a first bending in the method of manufacturing the square steel pipe.

FIG. 9 is a front view of a second bending in the method of manufacturing the square steel pipe.

FIG. 10 is a front view of a third bending in the method of manufacturing the square steel pipe.

FIG. 11 is a front view of a fourth bending in the method of manufacturing the square steel pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel plate 2 Groove 3 Right angle bent part (corner) 4 Right angle bent part (corner) 4A Obtuse angle bent part 5 Intermediate flat plate part 6 Side flat plate part 7 End flat plate part 8 Approximate square steel pipe 9 Square shape Steel pipe 10 Temporary welding 11 Butt weld 12 Square steel pipe (product) 20 Pre-stage forming press device 23 Post-stage forming press device 28 Transfer table 30 Forming device 31 Pre-stage forming device portion 33 Supporting means 34 Roller 36 Cylinder device 39 Rotary drive device 41 Movable inner mold 43 Movable frame 44 Cylinder device for lifting / lowering 46 Operating body 51 Movable outer die 52 Cylinder device for lifting / lowering 54 Cradle 55 Cylinder device 61 Side pressing means 62 Side pressing die 63 Type holding frame 66 Type left / right moving device 71 Post-stage molding unit 72 Roll 73 Roll 76 Feed roller 78 Carry table 81 Temporary attachment Welding means 84 Temporary welding machine 88 Carry-out table A Forming movement path W Width direction L Long opening length l Short opening length

Claims (3)

[Claims] 1. An approximate square steel pipe obtained by bending two portions of a steel plate near a groove corresponding portion in the width direction at right angles and bending two portions inside the right bent portion at an obtuse angle. A device for forming into a shaped steel pipe, comprising a pre-forming device portion and a post-forming device portion, wherein the pre-forming device portion has support means for supporting and guiding the approximate square-shaped steel tube in the length direction with its opening facing upward. A movable inner mold and a movable outer mold capable of sandwiching the intermediate flat portion between the obtuse-angled bent portions of the approximate square steel pipe released from the support by the supporting means, and a movable inner mold and a movable outer mold, which are sandwiched by the movable inner mold and the movable outer mold. A pair of side flat plate portions connected to the intermediate flat plate portion are formed by side pressing means that is bent inward so as to approach a right angle,
The rear-stage forming unit is configured by right and left rolls and upper and lower rolls so as to press the pair of side plate portions inward to form both obtuse bent portions into right-angled bent portions. Equipment for forming steel pipes. 2. The support means comprises a group of rollers, and is configured to be switchable between a support guide position and a support release position with respect to the approximate square steel pipe by moving the rollers in the axial direction of the rollers. 2. The apparatus for forming a square steel pipe according to claim 1. 3. The square according to claim 1, wherein the side pressing means comprises a pair of left and right side pressing dies, and a die left and right moving device for moving the side pressing dies left and right. Forming equipment for shaped steel pipes.