JPH10216839A - Forming press device for producing square steel tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a square steel tube producing press device whose bending in the final stage is executed by making its opening part small in the production of the square tube. SOLUTION: A holder 6 having an upper die 5 on the lower end is composed of an upper position member 7, an intermediate position member 8 and a lower position member 9, the intermediate position member 8 is formed in a circular shape and the thickness 11 of the upper position member 7 is formed smaller than the diameter 12 of the intermediate member 8. The transmission of the pressing force (bending stress) is collected to the just under in the upper position member 7 and it is collected in a shrink like after dispersing in a bulging like along the circular shape in the intermediate position member 8 and it is made in the just under in the lower position member 9, so because pressing is executed without being acted almost with the bending load and the transmission of enough pressing force is executed. The opening part 13 between the grooves 22 can be made small (narrow), and the corner parts 25, 26 are bent in a near angle to the bending angle of the product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forming method for manufacturing a square steel pipe having a large diameter and a large thickness, such as a rectangular or rectangular parallelepiped used for building pillars. It relates to a press device.

[0002]

2. Description of the Related Art Conventionally, square steel pipes have been manufactured 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 moved.
To form grooves 22 on both side edges 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 positions near the side edge by the raising and lowering movement of 43.

[0005] Next, as shown in FIG. 5, the steel strip 21 is put into a forming press 44 at a later 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 points. )
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 rectangular shape 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 performed, whereby a large-diameter and thick-walled square steel pipe (product) 32 having a butt welding portion (seam welding portion) 31 on one side can be manufactured.

[0005]

However, according to the conventional manufacturing method described above, in the bending forming in the forming press device 44 in 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 thereof.

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 enough to withstand the huge bending load required for press molding and to sufficiently transmit the huge press force required for press molding.
As a result, at the time of molding with 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 bent at an obtuse angle in the latter forming press device 44 and then pressurized from the outside to form a right angle. 25 and 26
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 different and hard to be uniform, so that the quality of the square steel pipe 32 becomes poor.

Accordingly, an object of the present invention is to provide a forming press apparatus for manufacturing a square steel pipe which can be bent and formed with a small opening.

[0009]

According to a first aspect of the present invention, there is provided a press apparatus for manufacturing a rectangular steel pipe, comprising: bending a plurality of portions in a width direction of a steel sheet; By pressurizing, one butted portion is formed, and in order to produce a square steel pipe by welding this butted portion, a forming press device including a lower mold and an upper mold that performs at least the final stage of bending is an upper press. A holder having a mold at a lower end is composed of a combined body of 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 has a thickness of the upper member. Is formed smaller than the diameter of the intermediate member.

Therefore, according to the first aspect of the present invention, a steel sheet obtained by bending and forming a corner corresponding to a product bending angle such as a right angle at a plurality of places 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 with respect to the lower mold. During this molding, the pressing force (bending stress) is transmitted to the upper mold via the holder, and at that 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 directly 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 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 rectangular 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 bend radii aligned with the corners, that is, the shapes of all the corners can be made uniform.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS 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-described conventional system are used except for the forming press at the latter stage, so that the same or almost the same components are denoted by the same reference numerals and the details thereof are omitted. 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 to 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 the upper member 7, the intermediate member 8, and the 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 set in the vertical 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 plate-shaped, the length direction of which is along the length direction of the strip steel plate 21, the width direction is the up-down 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 having a predetermined arc shape on the lower surface side. 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 the 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 upper mold 5 is put into the forming press device 1 at the latter 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 device 1 at the subsequent stage, the lowering force of the elevating body 4, that is, the pressing force (bending stress) is transmitted to the upper die 5 through 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 upper part 7 is transmitted right below, and the upper half part of the intermediate member 8 is swelled downward along a circle and dispersed downwardly. Are gathered downward in a contracted shape along the circle, and then transmitted directly below the lower member 9.

As a result, while the thickness 11 of the upper member 7 is formed 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. 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.

Then, at the part of the tack welding machine, the four sides are pressed against each other from outside by means of a roll group or the like, and the grooves 22 are butted together to perform welding, thereby forming 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 the corners 23 and 24
, That is, the shapes of the corners 23 to 26 can be made uniform. As a result, the square steel pipe as 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 this 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 be approximately half of the diameter 12 of the intermediate member 8, but if the thickness 11 is small, the ratio is arbitrary. 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 rectangular steel pipe, a small-diameter, thin-walled rectangular steel pipe, and a hexagonal steel pipe or an octagonal steel pipe may be manufactured.

[0024]

According to the first aspect of the present invention, when the pressing force (bending stress) at the time of molding is transmitted to the upper die via the holder, the transmission of the pressing force at the holder portion is performed. In the upper part, the lower part of the middle member is bulged and dispersed downward along the circle, and the lower part of the middle member is shrunk downward along the circle in the upper half part. In the part of the member, it can be performed directly below, so that 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 The transmission of the pressing force can be performed. 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.

Then, by applying pressure from the outside and performing welding, a large-diameter and thick-walled rectangular steel pipe (product) can be manufactured.
At that time, the square steel pipe, which is a product, can be formed not only in the size of the bending radius at each corner but also in the shape of the bending radius, so that it has good quality, and is particularly suitable for 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 die and a holder 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.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lower-stage forming press device 3 Lower die 4 Elevator 5 Upper die 6 Holder 7 Upper member 8 Intermediate member 9 Lower member 11 Thickness of upper member 12 Diameter of intermediate member 13 Opening 21 Strip steel plate (steel plate) 22 Grooves (side edges) 23 Corners 24 Corners 25 Corners 26 Corners 31 Butt welds 32 Square steel pipes (products) 41 Forming press at the preceding stage

Claims (1)

[Claims] A steel plate is bent at a plurality of positions in the width direction and then pressed from the outside to form one butt portion, and the butt portion is welded to produce a square steel pipe. A molding press device comprising a lower mold and an upper mold for bending a step, a holder having an upper mold at a lower end is formed of a combined body of an upper member, an intermediate member and a lower member, and the intermediate member is A forming press device for producing a square steel pipe, wherein the forming member is formed in a circular shape when viewed from the longitudinal direction of the steel sheet, and the thickness of the upper member is smaller than the diameter of the intermediate member.