JP2009050871A - Method of forming stepped portion of square pipe and die therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of forming a stepped portion in a required place of a square metallic pipeb simply without causing strain such as wrinkles on the upper surface of the stepped portion and the upper surface of the square pipe. <P>SOLUTION: After inserting an inner die composed of an upper inner die 11 having a stepped portion forming punch pressing surface 13 and upper surfaces 14-1, 14-2 of a presser which are higher than the pressing surface and also having an inclined sliding underside 15 and a lower inner die 12 having an inclined sliding upside 16 into a square pipe to be worked, by making the sliding upside 16 of the lower inner die 12 slide along the sliding underside 15 of the upper inner die 11 and, in the state where the upper surface 14 of the presser of the upper inner die 11 is pressed against the inside upper wall of the square pipe to be worked, pressing a stepped portion forming punch against the stepped portion forming portion of the square pipe to be worked, the stepped portion is formed on the square pipe. After that, by making the interval between the upper surfaces 14-1, 14-2 of the presser of the upper inner die 11 and the base of the lower inner die 12 smaller than the inside height of the stepped portion, the whole of the inner die is taken out of a pipe end. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method of forming a stepped portion at a predetermined position of a metal square tube used for a floor or ceiling skeleton of a house or the like, or a rack of a three-dimensional warehouse or the like, and a mold therefor.

In houses and the like, floors are constructed by combining vertical beams and horizontal beams. If flooring is performed without any modification to the vertical and horizontal beams, the flooring will be the total height of each thickness. Therefore, in order to reduce the thickness of the floor assembly, incisions are made at the intersections of the beams. Conventionally, since wood has been used as such vertical beams and horizontal beams, cutting can be performed relatively easily.
However, in recent years, considering various problems of timber such as environmental destruction such as deforestation, secular change and poor quality, such a beam is used by housing manufacturers because of its high strength and stable quality. A material made of a metal square tube such as a steel tube is being used.

When using a metal square tube as a beam material, it is not possible to provide a stepped portion as easily as wood. Usually, as a mode in which a step portion is provided in a beam material made of a metal square tube, a method in which a notch is made in a direction perpendicular to the longitudinal direction of the square tube at a predetermined position and a deformation is applied to the notched tip portion. is there. Regardless of wood or metal square tube, if a step is provided by forming a notch, the strength of the portion may be reduced and the joint strength with the beam may be reduced. In order to compensate for the strength reduction of the stepped portion, a reinforcing member is arranged inside or outside each member, but the cost is high.
Therefore, the present applicants have proposed a housing material in which a step portion is formed without providing a notch, that is, without a decrease in strength, in Patent Document 1.
JP 2006-328876 A

As shown in FIG. 1, the housing material proposed in Patent Document 1 is provided with a stepped portion 2 having a predetermined length at an end portion of a metal square tube 1, and the stepped portion 2 has an upper surface. The side portions facing each other have flange portions 3 formed by folding the side portions in a bellows shape inwardly, and the upper surface of the stepped portion is continuous with the central upper surface of the square tube and the inclined surface 4. It is characterized by having.
Such a housing material was originally developed as a material for joists to be passed over the fork. Since a step portion having a flat upper surface is formed at the tube end of the metal square tube, a stable mounting structure can be obtained by placing the upper surface downward and placing it on a large pull. It is extremely useful as a material for joist.

However, it is not suitable for members that are used by crossing each other, such as vertical beams and horizontal beams. In order to use it for a vertical beam, a horizontal beam, etc., it is necessary to form a stepped portion at an intersecting portion, not at an end portion.
Further, in order to combine the vertical beam and the horizontal beam with high accuracy, it is required that the formed stepped portion and its surroundings have no distortion such as wrinkles.
The present invention has been devised to solve such a problem, and a step portion is formed at a required portion of a metal square tube, and distortion such as wrinkles is generated on the upper surface thereof and the upper surface of the square tube connected thereto. It aims at providing the method of shape | molding simply.

  In order to achieve the object, the stepped portion forming method for a square tube of the present invention has a stepped portion forming punch pressing surface and a stepped portion forming punch pressing surface parallel to the stepped portion forming punch pressing surface and higher than the pressing surface. It has the same height at the front and rear ends of the formed punch presser surface, and has parallel side wall surfaces with the same interval as the inner width of the square tube to be processed at the side, and the front end surface and the rear end surface on the lower side at the lower part. Upper inner mold having a slide lower surface inclined with respect to the end surface on the upper surface of the end presser, a bottom surface parallel to the stepped portion punch forming surface of the upper inner mold on the lower side, and an inner width of the square tube to be processed on the side The stepped portion forming punch press surface and the presser upper surface of the bottom surface and the upper inner mold when the upper and lower inner molds have parallel side wall surfaces with equal intervals and are matched with the inclined lower slide surface of the upper inner mold. Lower inside with slide upper surface inclined so that The inner mold composed of the mold is slid relatively between the slide upper surface of the lower inner mold and the slide lower surface of the upper inner mold, and the upper surface of the upper inner mold and the bottom surface of the lower inner mold Is inserted into the stepped portion forming portion of the square tube to be processed in a state where it is smaller than the inner height of the square tube to be processed, and then the slide upper surface of the lower inner mold is aligned with the slide lower surface of the upper inner mold. Slide the upper inner mold presser upper surface against the inner upper wall of the square tube to be processed, and the inner wall of the processed portion of the square tube to be processed becomes the step forming punch press surface of the upper inner mold. The stepped portion forming punch is pressed against the stepped portion forming portion of the square tube to be pressed so as to form the stepped portion, and then the pressure of the stepped portion forming punch is released, and the slide upper surface of the lower inner mold Slide the upper inner mold along the lower slide surface and press the upper inner mold presser upper surface and the lower inner mold. The spacing of the bottom surface, and wherein the retrieving in a state of being smaller than the inner height of the formed stepped portion across the inner die from square tube.

It is preferable that the step portion is formed after the step portion forming portion of the square tube to be processed is accommodated in the outer mold.
Moreover, if the bellows part shaping | molding preliminary process is performed previously in the step part formation site | part side part upper part of a to-be-processed square tube, a bellows part will be formed smoothly. As this bellows portion forming preliminary processing method, a method of pressing a long edge against the side surface upper portion of the stepped portion forming portion of the square tube to be processed is employed.
Furthermore, even if an upper inner mold having a stepped portion forming punch pressing surface and a side surface where a bellows-like collar portion accommodating cutout portion is provided is used, the bellows portion is similarly smoothly formed. The

  The inner mold used in the step forming method for the square tube has a stepped portion forming punch pressing surface and a stepped portion forming punch pressing surface which is parallel to the stepped portion forming punch pressing surface and higher than the pressing surface. Have the same height at the front and rear ends, and have side walls parallel to the inner side of the square tube to be machined at the side, and the front end presser upper surface side end surface and the rear end presser upper surface side at the bottom. An upper inner mold having a slide lower surface inclined with respect to the end surface, a bottom surface parallel to the step forming punch pressing surface of the upper inner mold at the lower portion, and an interval equal to the inner width of the square tube to be processed on the side portion The bottom surface and the stepped portion forming punch pressing surface and the pressing upper surface of the upper inner mold are parallel when having a parallel side wall surface and matching with the inclined lower slide surface of the upper inner mold at the top. Consists of lower inner mold with slide upper surface inclined to To have.

The step forming punch pressing surface and the two pressing upper surfaces of the upper inner mold may be connected by a vertical surface or may be connected by an inclined surface.
It is preferable that a notched portion for accommodating a bellows-like collar portion is provided at the intersection between the step-forming punch pressing surface and the side surface of the upper inner mold.
The inner mold and the step forming punch constitute a step forming mold for the square tube.
In addition, it is preferable to include an outer mold having a groove having a size capable of accommodating the stepped portion forming portion of the pipe to be processed and having an upper surface, a front surface, and a rear surface opened.

According to the present invention, as shown in FIG. 2, the upper surface of the stepped portion 2 having a flange portion 3 formed by folding the side portions in a bellows shape inwardly on opposite side surfaces on both sides of the square tube 1. Is continuous with the upper surface of the square tube and the inclined surface 4, and is also regulated by the stepped portion forming punch pressing surface and the upper surface of the step, so that the boundary portion between the inclined surface and the upper surface of the stepped portion of the inclined surface 4 Is suppressed, and the stepped portion 2 having excellent shape accuracy is formed.
In addition, since the upper surface position of the inner mold can be easily changed by relatively sliding the upper inner mold and the lower inner mold, the inner mold can be easily inserted into and removed from the square tube to be processed. The step portion can be formed at an arbitrary position.

Further, the cross section of the stepped portion 2 formed by the formation of the bellows-shaped collar portion 3 has high strength due to work hardening and shape effect. Therefore, when the square tube 1 having the stepped portion 2 is used as a beam, the distance between the fulcrums in the portion with low strength is shortened, the bending rigidity is increased, and the beam has a small deflection.
Furthermore, when the square tubes 1 formed with the stepped portions 2 are used as vertical beams and horizontal beams, positioning and level adjustment with other members are facilitated by combining the stepped portions as seen in FIG.
As described above, by adopting the present invention, a metal square tube having a stepped portion with excellent shape accuracy can be supplied at low cost, which can contribute to the spread of houses and three-dimensional warehouses whose basic skeletons are made of metal structures.

Below, the preferable aspect of the level | step difference formation method of this invention square tube is demonstrated based on drawing.
First, the structure of the inner mold used will be described.
As shown in FIG. 4, the inner mold 10 includes an upper inner mold 11 and a lower inner mold 12. The upper inner die 11 has a stepped portion forming punch pressing surface 13 and a pressing upper surface 14-1, 14 parallel to the stepped portion forming punch pressing surface 13 and higher than the stepped portion forming punch pressing surface 13. -2 and parallel side wall surfaces having an interval equal to the inner width of the square tube to be processed at the side, and the front end pressing upper surface 14-1 side end surface at the lower side is the rear end pressing upper surface 14-. It has an upper inner mold having a slide lower surface 15 inclined so as to be lower than the end surface on the second side.

The lower inner mold 12 has a bottom surface parallel to the step forming punch pressing surface 13 of the upper inner mold 11 at a lower portion thereof, and parallel side wall surfaces at intervals equal to the inner width of the square tube to be processed. When the upper inner mold 11 is made to coincide with the inclined lower slide surface 15 of the upper inner mold 11, the stepped portion forming punch pressing surface 13 and the pressing upper surfaces 14-1 and 14-2 of the upper inner mold 11 are formed. And the slide upper surface 16 inclined so as to be parallel to each other.
The mold for forming a step portion of the rectangular tube of the present invention includes an inner mold 10 composed of the upper inner mold 11 and the lower inner mold 12 as described above, and an inner mold not shown in FIG. A step portion forming punch disposed on the stepped portion forming punch pressing surface 13 of the mold is provided.
In FIG. 4, reference numeral 19 denotes a notch portion for forming a bellows-like collar portion which will be described later.

Here, an example of the slide form of the upper inner mold 11 and the lower inner mold 12 will be described using the inclined slide lower surface 15 and slide upper surface 16.
As shown in FIG. 5, a guide groove having a U-shaped cross section is formed in the longitudinal direction substantially at the center of the upper inner mold 11, and a guide rod 17 is inserted into the guide groove. The front end of the guide bar 17 is pinned to be movable in the vertical direction at the rear end of the guide groove.
On the other hand, a guide hole having a circular cross section with an inner diameter slightly larger than the diameter of the guide rod is penetrated in the longitudinal direction substantially at the center of the lower inner mold 12. The guide rod 17 positioned so that the tip cannot move in the longitudinal direction inside the upper inner mold 11 is in contact with the slide lower surface 15 of the upper inner mold 11 and the slide upper surface 16 of the lower inner mold 12. In this way, the guide hole of the lower inner mold 12 is inserted. Reference numeral 18 denotes an auxiliary rod for facilitating the insertion and removal of the lower inner mold 12.
5A shows a positional relationship in which the lower inner mold 12 is separated from the upper inner mold 11, and FIG. 5B shows the lower inner mold 12 as the upper inner mold 11. The positional relationship closest to is shown.

In the above embodiment, the slide lower surface 15 of the upper inner mold 11 is inclined so that the end surface on the front end pressing upper surface 14-1 side is lower than the end surface on the rear end pressing upper surface 14-2 side. In addition, the front end pressing upper surface 14-1 side end surface may be inclined so as to be higher than the rear end pressing upper surface 14-2 side end surface.
In this case, the direction of the inclination of the slide upper surface 16 of the lower inner mold 12 is also reversed. Moreover, in the aspect of the step forming process of the square tube described later, after the upper inner mold 11 is set at a predetermined position, the lower inner mold 12 is not pushed in, but pulled back from the inside of the square tube to the pipe end. Become.

Next, a method for forming a flat step portion at a required portion of a square tube using the above-described mold will be described with reference to FIG.
The inner mold 10 is inserted into the tube of the workpiece square tube M ((a) of FIG. 6). At this time, as shown in FIG. 5 (a), the lower inner mold 12 is inserted into the stepped portion forming portion in the pipe while maintaining the positional relationship separated from the upper inner mold 11. By making the height of the front end pressing upper surface 14-1 side end surface of the upper inner mold 11 lower than the inner height of the square tube to be processed, it can be easily inserted into the square tube.

Next, the insertion position of the upper inner mold 11 in the square tube is fixed, and only the lower inner mold 12 is pushed inward of the square tube. At this time, since the guide rod 17 is fixed in the longitudinal direction of the square tube, it is only necessary to push the lower inner mold 12 along the guide rod 17. When the lower inner mold 12 is pushed, the upper inner mold 11 is moved upward.
The lower inner mold 12 is pushed in until the presser upper surface 14 of the upper inner mold 11 comes into contact with the inner upper wall of the processed square tube M ((b) in FIG. 6).

  In a state where the upper pressing surfaces 14-1 and 14-2 of the upper inner mold 11 are in contact with the inner upper wall of the processed square tube M, the stepped portion forming punch 20 is placed on the upper surface of the tubular body from above the processed square tube. Press against. The stepped portion forming punch 20 is pressed against the processed square tube until the inner upper wall of the processed square tube M is pressed against the stepped portion forming punch pressing surface 13 of the upper inner mold 11 to form a stepped portion on the square tube. ((C) of FIG. 6). When the upper surface of the processed square tube M is deformed along the shape of the stepped portion forming punch pressing surface 13 of the upper inner mold 11, the inner wall of the processed square tube M is the upper inner mold 11 and the lower inner mold. Therefore, only the upper part of the side wall of the tube is deformed so as to be folded in a bellows shape inwardly.

After the step portion is formed at a required location of the square tube, the pressing of the step portion forming punch 20 is released. Thereafter, only the lower inner mold 12 is slid so as to be pulled out from the pipe, and the upper inner mold 11 is moved downward.
By making the height of the end surface on the front end pressing upper surface 14-1 side of the upper inner mold 11 lower than the inner height of the stepped portion of the square tube to be processed ((d) in FIG. 6), from inside the square tube, The inner mold 10 can be easily extracted. After this extraction step, the step forming process of the square tube is completed.

In the method of the present invention, the upper wall of the square tube M to be machined is regulated by the stepped portion forming punch pressing surface 13 and the pressing upper surfaces 14-1 and 14-2 provided in the upper inner mold 11. The deformation of the boundary portion with the central portion and the center-side upper surface is suppressed, and the step portion forming process of the square tube having excellent shape accuracy can be performed.
By the way, when viewed from the design surface, it is preferable that the R portion at the boundary portion with the upper surface of the stepped portion of the slope and the boundary portion with the upper surface at the center side is a small corner R, but when the corner R is small, the strain is concentrated on the R portion. However, the elongation limit of the material is exceeded and cracking occurs. Although the design of the product is inferior, in order to disperse the distortion of the R portion, the stepped portion forming punch pressing surface 13 side corner R of the upper inner mold, in particular, the presser pressing upper surfaces 14-1 and 14-2, should be made as large as possible. desirable. In setting the corner R, it is desirable to take a value equal to or greater than the allowable minimum bending radius of the material.

In order to further improve the forming accuracy, it is possible to perform the step forming process of the square tube after accommodating the step forming part of the processed square tube in the outer mold having the groove width equal to the width of the processed square tube. preferable.
When the square tube to be processed is processed and deformed, the outward movement is also restricted, so there is no outward protrusion, and the forming accuracy is further improved as a result of the shape.
In order to smoothly perform the step forming process of the square tube, the bellows part forming preliminary processing may be performed in advance on the upper part of the step forming part of the processed square tube. As preliminary processing for forming the bellows portion, it is preferable to press a long edge against the upper portion of the stepped portion forming portion of the square tube to be processed.
If the upper inner mold 11 is provided with a bellows-shaped collar portion accommodating notch 19 (see FIG. 4) at the intersection of the stepped portion forming punch pressing surface 13 and the side surface, a bellows-like shape is used. The collar portion is easily formed, and as a result, the step portion forming process of the square tube having excellent shape accuracy can be performed.

The figure which illustrates roughly the structure of the square tube in which the level | step-difference part was formed in the pipe end part The figure which illustrates roughly the structure of the square tube in which the level | step-difference part was formed in the required location The figure which illustrates roughly the combination structure of the square tube in which the level | step-difference part was formed in the required location The figure explaining the shape of the inner metal mold used for this invention level difference part formation processing The figure explaining the usage form of the inner mold used for this invention level difference part formation processing Sectional drawing explaining the processing procedure of this invention level | step-difference part formation method

Explanation of symbols

1: joist 2: stepped portion 3: bellows-shaped collar portion 4: inclined portion
10: Inner mold 11: Upper inner mold 12: Lower inner mold 13: Stepped portion forming punch pressing surface
14-1, 14-2: Presser upper surface 15: Slide lower surface 16: Slide upper surface
17: Guide rod 18: Auxiliary rod 19: Notched portion for forming bellows-shaped collar portion
20: Step forming punch

Claims (8)

  The upper portion has a stepped portion forming punch pressing surface and a pressing upper surface parallel to the stepped portion forming punch pressing surface and higher than the pressing surface at the same height as the front end and the rear end of the stepped portion forming punch pressing surface, and a side portion. The upper inner mold having a parallel side wall surface having an interval equal to the inner width of the square tube to be processed, and a lower slide surface inclined between the front end presser upper surface side end surface and the rear end presser upper surface side end surface at the lower part A bottom surface parallel to the step forming punch pressing surface of the upper inner mold at the lower part, and a parallel side wall surface having a distance equal to the inner width of the square tube to be processed at the side part, and the upper inner metal at the upper part. Consists of a lower inner mold having a slide upper surface inclined so that the bottom surface and the stepped portion forming punch pressing surface and presser upper surface of the upper inner mold are parallel when matched with the inclined slide lower surface of the mold The inner mold that is The workpiece is slid relative to the bottom surface of the inner mold, and the distance between the upper surface of the upper inner mold and the bottom surface of the lower inner mold is smaller than the inner height of the square tube to be processed. After inserting into the step forming part of the square tube, slide the upper surface of the lower inner mold along the lower slide surface of the upper inner mold to place the upper surface of the upper inner mold on the inner upper wall of the processed square tube. In the pressed state, the stepped portion forming punch is placed on the stepped portion forming portion of the processed square tube so that the inner wall of the processed portion of the processed square tube is pressed against the stepped portion forming punch pressing surface of the upper inner mold. Press to form a stepped portion, and then release the stepped portion forming punch and slide the upper surface of the lower inner mold along the lower surface of the upper inner mold to hold the upper inner mold. The distance between the top surface and the bottom surface of the lower inner mold is made smaller than the inner height of the formed step. It stepped part forming method of the corner pipe, characterized in that retrieving the entire inner die while the square tube.   The method for forming a step portion of a square tube according to claim 1, wherein the step portion is formed after the step portion forming portion of the processed square tube is accommodated in the outer mold.   The step part forming method of the square tube according to claim 1 or 2, wherein preliminary processing for forming a bellows part is performed in advance on a side surface upper part of the step part forming part of the square tube to be processed.   The method for forming a step portion of a square tube according to claim 3, wherein a long edge is pressed against the upper part of the side surface of the step portion forming portion of the square tube to be processed.   The square tube according to any one of claims 1 to 4, wherein an upper inner mold is provided with a notched portion for accommodating a bellows-like collar portion at an intersecting portion between a stepped portion forming punch pressing surface and a side surface. Stepped portion forming method.   The upper portion has a stepped portion forming punch pressing surface and a pressing upper surface parallel to the stepped portion forming punch pressing surface and higher than the pressing surface at the same height as the front end and the rear end of the stepped portion forming punch pressing surface, and a side portion. The upper inner mold having a parallel side wall surface having an interval equal to the inner width of the square tube to be processed, and a lower slide surface inclined between the front end presser upper surface side end surface and the rear end presser upper surface side end surface at the lower part. A bottom surface parallel to the step forming punch pressing surface of the upper inner mold at the lower part, and a parallel side wall surface having a distance equal to the inner width of the square tube to be processed at the side part, and the upper inner metal at the upper part. Consists of a lower inner mold having a slide upper surface inclined so that the bottom surface and the stepped portion forming punch pressing surface and presser upper surface of the upper inner mold are parallel when matched with the inclined slide lower surface of the mold Inner mold and stepped portion forming pan of the inner mold Stepped portions formed mold of square tube, characterized in that it comprises a step portion formed punch disposed on the pressing surface.   7. A step forming mold for a square tube according to claim 6, wherein a step for forming a stepped portion of the upper inner mold is provided with a notched portion for accommodating a bellows-like collar portion at the intersection of the punch pressing surface and the side surface.   8. The step forming portion of the square tube according to claim 7, further comprising an outer mold having a groove having a size capable of accommodating a step forming portion of the square tube to be processed and having an upper surface, a front surface, and a rear surface opened. Mold.

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