JP3497057B2 - Forming press equipment for producing square steel pipes - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a large-diameter, thick-walled rectangular steel pipe having a rectangular shape or a rectangular parallelepiped shape used for, for example, a column material for building. The present invention relates to a forming press device for producing square steel pipes, which is employed in the present invention. [0002] Conventionally, the manufacture of a square steel pipe has been carried out as follows. That is, as shown in FIG. 4, the strip steel plate 21 is transported in the length direction 21A, and the trimming beveling machine 40 is transported.
Through the groove 22 on both sides in the width direction 21B,
Before and after this, it is cut to a predetermined length. Then, the strip steel plate 21 is put into the former forming press device 41, and the upper die
The right and left corners 23 and 24 are bent and formed at two places near the side edge by the vertical movement of 43. [0005] Next, as shown in FIG. 5, the strip steel plate 21 is put into a forming press device 44 at the subsequent stage, and the upper die 46 is moved up and down with respect to the lower die 45 to form an obtuse angle (about 105 degrees) at two intermediate positions. )
The corners 25 and 26 are bent and formed. Then, in the part of the tack welding machine 47, the four sides are pressed from the outside by a group of rolls 48, 49 (or a cylinder) to form obtuse corners 25, 26.
The grooves 22 are butted against each other while being formed into a right angle to form a square steel pipe 27, and tack welding 28 is performed on the butted portions. [0004] Next, as shown in FIG.
After transferring 27 to the internal welding machine 50 and performing the internal welding 29,
It is transferred to the outer surface welding machine 51 and the outer surface welding 30 is carried out, whereby a large-diameter and thick-walled square steel pipe (product) 32 having a butt weld portion (seam weld portion) 31 on one side can be manufactured. However, according to the above-described conventional manufacturing method, in the bending forming by the forming press device 44 at the subsequent stage, the corners 25 and 26 are formed at a right angle (90 degrees) as much as possible.
In order to form the holder so as to be close to the shape, a holder 52 having a “U” shape (gooseneck shape) is employed, and the holder 52 is formed by an upper mold 46 provided at a lower end of the holder 52. In this case, a bending load is applied to the holder 52 because the holder 52 is bent in the shape of a "ku".
In addition, a pressing force (bending stress) is transmitted through a portion that is bent in the shape of a “<”. Therefore, the thickness of the holder 52 needs to be large so as to withstand a huge bending load required for press molding and to sufficiently transmit a huge pressing force required for press molding.
As a result, at the time of molding by the molding press device 44, the opening 35 between the grooves 22 is inevitably large (wide) and must be formed at the large obtuse corners 25 and 26. Therefore, the corners 23 and 24 bent at a right angle in the former forming press device 41 and the corner portions formed into a right angle by being bent at an obtuse angle in the latter forming press device 44 and then pressed from the outside. 25 and 26 are
The shapes of the bending radii r, R as well as the sizes of the bending radii r, R will be different, that is, the corners 23, 24, 2
The shapes of the pieces 5 and 26 are not uniform and hard to be uniform, so that the quality of the square steel pipe 32 is poor. Accordingly, an object of the present invention is to provide a forming press device for manufacturing a square steel pipe which can be bent and formed with a small opening. [0009] In order to achieve the above-mentioned object, a press apparatus for manufacturing a rectangular steel pipe according to claim 1 of the present invention, after bending a plurality of portions in a width direction of a steel sheet. Forming one butted portion by applying pressure from the outside, and manufacturing a square steel pipe by welding this butted portion, a forming press device comprising a lower mold and an upper mold that perform at least the final stage of bending. A holder having an upper mold at a lower end thereof is formed of a combined body of an upper member, an intermediate member, and a lower member, and the intermediate member is formed in a circular shape when viewed from the length direction of the steel sheet, The thickness of the member is formed smaller than the diameter of the intermediate member. Therefore, according to the first aspect of the present invention, the steel sheet obtained by bending and forming a corner corresponding to a product bending angle such as a right angle at a plurality of positions is formed by a final-stage forming press device.
The corner can be bent and formed at the final location by the vertical movement of the upper mold relative to the lower mold. During this molding, the pressing force (bending stress) is transmitted to the upper mold via the holder, and at this time, the transmission of the pressing force at the holder portion is transmitted directly below the upper member portion, and then at the intermediate position. In the upper half of the member, it bulges down along the circle and disperses downward, then in the lower half of the middle member, it shrinks down along the circle and gathers down, then in the lower part, it transmits just below Will be. As a result, while the thickness of the upper member is formed smaller than the diameter of the intermediate member, press forming can be performed with almost no bending load, and sufficient pressing force can be transmitted. Since the thickness of the upper member can be made small, the opening between the grooves can be made small (narrow), and the corner can be bent and formed at an angle close to the product bending angle. Thereafter, by performing welding while applying pressure from the outside, a large-diameter and thick-walled square steel pipe (product) can be manufactured. At this time, the corner formed at the final stage is bent at an angle that is not much different from the corner of the product bending angle bent at the previous stage, so forming by pressing from the outside is the product bending angle. , That is, the shapes of all corners can be made uniform. Embodiments of the present invention will be described below.
A state in which a square steel pipe is manufactured will be described with reference to FIGS. In manufacturing a square steel pipe, the same components as those of the above-mentioned conventional system are used except for the forming press at the latter stage. I do. That is, in FIG. 1, 21 is a strip steel plate (an example of a steel plate), 22 is a groove (side edge), 23
26 indicates a corner. As shown in FIG. 1, the molding press 1 at the subsequent stage comprises a lower mold 3 fixed on a press table 2 and an upper mold 5 attached to a lifting body 4 via a holder 6. You. The holder 6 is composed of a combination of an upper member 7, an intermediate member 8, and a lower member 9. The upper member 7 is plate-shaped, and its length direction is set along the length direction of the strip steel plate 21, and its width direction is the up-down direction. The intermediate member 8 has a rod shape made of cast steel,
The upper member 7 has a circular shape when viewed from the longitudinal direction of the steel strip 21.
Is fixed to the lower surface of the device by welding 10 or the like. The lower member 9
Is a plate-like shape, the length direction of which is along the length direction of the strip steel plate 21, the width direction is the vertical direction, and the upper part is fixed to the lower surface of the intermediate member 8 by welding 10 or the like. I have. In addition, the lower mold 9 is integrally formed with an upper mold 5 whose lower surface side has a predetermined arc shape. Here, the thickness 11 of the upper member 7 is formed smaller (about half) than the diameter 12 of the intermediate member 8. The operation of the above embodiment will be described below. In the former forming press device, the strip steel sheet 21 in which the corners 23 and 24 of a right angle (90 degrees or almost 90 degrees corresponding to the product bending angle) are bent at two places near the side edge is then formed. Then, the lower mold 3 is put into the molding press 1 at the later stage (final stage), and the upper mold 5 is moved up and down with respect to the lower mold 3 so that the obtuse corners 25 and 26 are bent at two intermediate positions. At the time of molding by the molding press 1 at the subsequent stage, the descending force of the elevating body 4, that is, the pressing force (bending stress) is transmitted to the upper mold 5 via the holder 6.
At this time, the transmission of the pressing force at the holder 6 is performed as shown in FIG.
As shown by the arrow, the lower part of the intermediate member 8 is transmitted to the lower part of the intermediate member 8 after being transmitted directly below the upper member 7 and swelling downward along the circle in the upper half of the intermediate member 8. Are gathered downward in a shrinking shape along the circle, and then transmitted directly below in the lower member 9 portion. As a result, while the thickness 11 of the upper member 7 is made smaller than the diameter 12 of the intermediate member 8, press forming can be performed with almost no bending load.
Sufficient pressing force can be transmitted. And, since the thickness 11 of the upper member 7 can be made small, the opening 13 between the grooves 22 can be made small (narrow), so that the corners 25 and 26 are close to a right angle (product bending angle). It can be bent to a small obtuse angle. Thereafter, in a tack welding machine, the four sides are pressed against each other by a roll group or the like from the outside, butts 22 are joined together, and welding is performed to form a large-diameter thick-walled square steel pipe (product). ) Can be produced. At this time, since the corners 25 and 26 are bent at a small obtuse angle which is not so different from the corners 23 and 24 bent at a right angle in the former molding press, pressure from outside is applied. The right angle molding by corners 23, 24
, That is, the shapes of the corners 23 to 26 can be made uniform. As a result, the rectangular steel pipe, which is a product, has a uniform bending radius as well as the bending radius of each of the corners 23 to 26, and thus has high quality. In the above-described embodiment, the molding press 1 is used in the latter stage, but it may be used in the former molding press as well. In the above-described embodiment, the thickness 11 of the upper member 7 is set to about half of the diameter 12 of the intermediate member 8, but the ratio is arbitrary if the thickness 11 is small. It is. In the above-described embodiment, a large-diameter, thick-walled square steel pipe (product) having a butt weld (seam weld) on one side is manufactured. A small-diameter, thick-walled square steel pipe, a small-diameter, thin-walled square steel pipe, and a hexagonal steel pipe or an octagonal steel pipe may be manufactured. According to the first aspect of the present invention, when the pressing force (bending stress) during molding is transmitted to the upper mold through the holder, the pressing force at the holder is used. In the upper part, the lower part of the middle member bulges downward along the circle, and the lower part of the middle member shrinks downward along the circle. The lower member can be formed directly below the lower member, and as a result, the thickness of the upper member can be formed smaller than the diameter of the intermediate member, but the press forming can be performed with almost no bending load. At the same time, a sufficient pressing force can be transmitted. Since the thickness of the upper member can be made small, the opening between the grooves can be made small (narrow), and the corner can be bent and formed at an angle close to the product bending angle. Thereafter, by applying pressure from the outside and performing welding, a large-diameter, thick-walled rectangular steel pipe (product) can be manufactured.
At that time, the square steel pipe, which is a product, has a uniform bending radius as well as the size of the bending radius at each corner, and thus has good quality, and is particularly suitable for a large diameter and thick wall. Can manufacture steel pipes.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an example of an embodiment of the present invention and is a front view of a forming press device for producing a square steel pipe. FIG. 2 is a perspective view of a main part of an upper mold and a holder part in a forming press apparatus for manufacturing a square steel pipe. FIG. 3 is an explanatory diagram of an operation at the time of pressing in a forming press apparatus for manufacturing a square steel pipe. FIG. 4 shows a conventional example, and is an explanatory view up to a two-corner forming step in the production of a square steel pipe. FIG. 5 is an explanatory view up to a tack welding step in the manufacture of the rectangular steel pipe. FIG. 6 is an explanatory view up to a final step in manufacturing the rectangular steel pipe. [Description of Signs] 1 Post-stage forming press device 3 Lower die 4 Elevator 5 Upper die 6 Holder 7 Upper member 8 Middle member 9 Lower member 11 Thickness of upper member 12 Diameter of middle member 13 Opening 21 Strip steel plate (steel plate) 22 Groove (side edge) 23 Corner 24 Corner 25 Corner 26 Corner 31 Butt weld 32 Square steel pipe (product) 41 Forming press at the preceding stage

Claims (1)

(57) [Claims 1] A steel plate is bent at a plurality of positions in the width direction, and then pressurized from the outside to form one butt portion, and the butt portion is welded. In order to manufacture a square steel pipe, a forming press device including a lower mold and an upper mold for bending at least the final stage includes a holder having an upper mold at a lower end, and a coupling between an upper member, an intermediate member, and a lower member. The intermediate member is formed in a circular shape when viewed from the longitudinal direction of the steel plate, and the thickness of the upper member is smaller than the diameter of the intermediate member. Forming press equipment for producing square steel pipes.