JPS5927658B2 - Bending method for U-shaped cross-sectional material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for bending a U-shaped cross-sectional material, and in particular,
The present invention relates to a method of bending a U-shaped cross-sectional member with its opening facing inside.

A U-shaped cross-section member subjected to this type of bending process is used, for example, as a handrail member for a passenger conveyor.

An example of its use will be explained using the passenger conveyor shown in FIGS. 1 and 2. The railing of the passenger conveyor is composed of a large number of stationary parts excluding the rotating members of the step 1 and the handrail 2, and includes a main deck 3 that supports the handrail 2,
It consists of a combination of design members such as a guide guide 4, a lower guide 5, a terminal deck 6, and a handrail panel T, and auxiliary members such as a guide roller 8 and a packing 9.

By the way, the main deck 3, guide deck 4, which are design members,
The lower deck 5 and the terminal deck 6 are increasingly made of stainless steel with a thickness of about 1 to 3 mm, in response to the trend toward higher-end designs.

This stainless steel balustrade replaces the aluminum alloy balustrade that has traditionally been heavily used, and in addition to the high-class image unique to stainless steel, it also has outstanding durability. However, the railing of the passenger conveyor has a unique streamlined curve from the lower entrance (not shown) to the upper entrance, with a concave curved section (not shown), a convex curved section U, and a terminal curved section V. Therefore, the problem is how to bend the stainless steel balustrade member without impairing its design.

Hereinafter, problems during bending will be explained using the main deck 3 with the terminal curved part as a representative example of the parapet member made of stainless steel plate. The main deck 3 includes a web 3a that is flat in the width direction on which a guide deck 4 that guides the travel of the handrail 2 is placed, and a web 3a that is bent in the same direction from both sides of the web 3a so as to cover the line of the handrail panel 1. It has a U-shaped cross section with a bent flange 3b, and its dimensions are approximately 3 in height to 10 in width.

As shown in FIGS. 3 and 4, the main deck 3 is manufactured by bending a straight U-shaped cross-sectional member 10 so as to wrap it around a bending die 11. The bending die 11 used for this bending process is curved with a required curvature and has a flat band-shaped outer peripheral surface in the width direction as a die surface 11a, and has a U-shaped cross section on both sides of this die surface 11a. It has a groove 11b into which ten flanges 10b are inserted. The inner surface of the web 10a of the U-shaped cross-sectional member 10 comes into contact with the mold surface 11a. The bending process is
Both ends of the U-shaped cross-section member 10 are gripped by a bending machine, and both ends are moved in the direction of arrow Y while applying a tensile force to the U-shaped member 10, and finally a tensile force in the direction of arrow X is applied. do. In order to allow the flange 10b of the U-shaped cross-section member 10 to fit comfortably into the groove 11b of the bending die 11 during this bending process, the width of the groove 11b is set larger than the thickness of the flange 10b. Therefore, a gap g exists between the inner wall of the groove 11b and the flange 10b. As shown in FIGS. 5 and 6, the bent U-shaped cross-sectional material 10 has a radius of curvature of R on its outer peripheral surface and a radius of curvature of R2 on its inner peripheral surface during the bending process. There is a neutral plane with a radius of curvature R3 that neither expands nor contracts, and the side outside this neutral plane, that is, the web 10a side, is the expansion side, and the inside side is the contraction side.

However, since the above-mentioned gap g exists, the flange 10b inside the neutral plane is given a degree of freedom of deformation corresponding to the gap g, and there is a problem in that wrinkles S occur. Furthermore, when wrinkles S occur on the flange 10b, the shoulder portion 10c of the U-shaped cross-sectional member 10 does not follow the curvature of the bending die 11, and as shown in FIG. 7, the web 10a is warped in the width direction. A problem occurs that occurs.

This is because the shoulder portion 10c is the intersection of the web 10a and the flange 10b and has the strongest structure in the cross section, so the shoulder portion 10c cannot be bent completely. When the web 10a is warped in this way, when the web 10a is used as the main deck 3, the guide deck 4
Since a gap is formed at the joint with the other material, there is a drawback that the joint strength is reduced, and it is also undesirable from a design point of view. SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a method for bending a U-shaped member in cross section in which the web does not warp.

In order to achieve this objective, the present invention utilizes a U-shaped cross-section,
In a method of tensile bending by applying the inner surface of the web to the surface of a bending die, the width of the surface of the bending die is such that the shoulder of the U-shaped cross-sectional material is dropped during the tension bending process. is narrower than the width of the web of the U-shaped cross-sectional member.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. In this example, a method of bending a U-shaped cross-section member shown in FIG. 8 will be described.

This U-shaped cross-section member 12 has a web 12a and a flange 12b.
In addition, the flange 12b has a lip 12d that protrudes from the tip end in a direction that narrows the width of the opening 12e.
The lip 12d is effective in preventing wrinkles from forming on the flange 12b, as will be described later. FIG. 9 shows the bending method of this embodiment. The bending die 13 has a die surface 13a consisting of a belt-shaped outer peripheral surface that is curved with a required curvature and is flat in the width direction.
The inner surfaces of the webs 12a of No. 2 are in contact with each other, and the mold surfaces 1
As in the conventional case, grooves 13b into which the flanges 12b of the U-shaped cross-sectional member 12 are inserted are formed on both sides of the groove 3a.

In this embodiment, the width W2 of the mold surface 13a is narrower than the width W of the web 12a of the U-shaped cross-sectional member 12 before bending minus the width 2W3 of the lips 12d on both sides.

Further, the depth H of the groove 13b is made somewhat deeper than the inner surface height H2 of the flange 12b, so that a gap h is created between the groove bottom and the lip 12d. Furthermore, the width of the inner part of the groove 13b is approximately the same as the width W3 of the lip 12d.
Therefore, when bending the tip of the flange 12b,
Although the groove 13b can freely move in the depth direction, its movement in the width direction is restricted. When the bending die 13 is used to bend the U-shaped member 12, the result will be as follows. First, with a tensile force applied to the U-shaped cross-sectional member 12, the inner surface of the web 12a is brought into contact with the mold surface 13a.

Next, the U-shaped cross-section member 12 is gradually wound around the mold surface 13a while applying a tensile force. At this time, the flange 12b
Since the tip of the web 12a does not reach the bottom of the groove 13b and is free to move in the depth direction of the groove 13b, the web 12a is strongly pressed against the mold surface 13a. However, the shoulder portion 12c
Since the web 12a in the vicinity does not come into contact with the mold surface 13a, a shoulder drop T, naturally occurs in this part. However, due to the occurrence of this shoulder drop T, the main portion of the web 12a is uniformly pressed against the mold surface 13a, and flatness in the width direction is ensured. Also, flange 1
Since the tensile force is applied while the movement of the tip of the web 2b in the width direction is restricted, this tensile force acts to contract the width of the web 12a, and as a result, the shoulder drop T2 in the width direction is also reduced. will occur. On the other hand, the rigidity of the flange 12b on the tip side is increased by the lip 12d formed at the tip, and this increases the rigidity of the flange 12b on the neutral plane of bending (see Fig. 6, R
3) is displaced toward the tip of the flange 12b to balance the expansion side and the contraction side, and the tip of the flange 12b is restricted from moving in the width direction by the groove 13b. The occurrence of wrinkles on 12b also disappears.

In this way, by intentionally generating shoulder drops T, T2, it is possible to completely prevent the occurrence of warping of the web 12a, and by adding the reinforcing action of the lip 12d to this, the flange 12b is The generation of wrinkles can also be prevented.

FIG. 10 shows an example in which the cross-sectional Y-shaped member bent as described above is used as the main deck 3 of a passenger conveyor.

Since the web 3a of the main deck 3 is flat in the width direction except for the shoulder portion 3c, it can be reliably joined to the guide deck 4. This main deck 3 has a shoulder drop T,,T2
However, since this shoulder drop occurs uniformly, it is not unsightly, and depending on how you look at it, a soft line appears, which is interesting in terms of design. Further, even if the shoulders drop T, , T2, there is no problem in attaching the terminal deck 6 and the handrail panel 7. In the above example,
Although a U-shaped member with a flange having a lip formed at the tip thereof was used, the present invention is also applicable to bending of a U-shaped member without a lip. In that case, the width of the deep part of the groove of the bending mold should be made approximately the same as the plate thickness of the tip of the flange. As explained above, according to the present invention, it is possible to prevent the web from warping by causing shoulder drop when bending a U-shaped cross-sectional member.

Furthermore, if the movement of the flange tip end in the width direction is restricted in the inner part of the groove of the bending die, it is possible to prevent wrinkles from forming on the flange.

[Brief explanation of the drawing]

Fig. 1 is a side view of the upper part of the passenger conveyor, Fig. 2 is a cross-sectional view taken along the line in Fig. 1, Fig. 3 is a perspective view showing the conventional bending method, and Fig. 4 is a cross-sectional view taken along the - line in Fig. 3. Figure 5 is a perspective view of a U-shaped cross-sectional material bent by the conventional method, Figure 6 is a perspective view of a U-shaped cross-section
The figure is a cross-sectional view taken along the line -- in FIG. 5, FIG. 7 is a cross-sectional view showing problems in the conventional bending method, and FIG. 8 is a U-shaped cross-sectional view used in an embodiment of the bending method of the present invention. 9 is a sectional view showing an embodiment of the bending method of the present invention,
FIG. 10 is a sectional view of a railing portion of a passenger conveyor using a U-shaped cross-sectional member bent according to this embodiment. 12... U-shaped cross section, 12a... Web, 12b... Flange, 12c...
・Shoulder, 12d...Rip, 13...
Bending mold, 13a... Mold surface, 13b...
Groove, T,, T2... Shoulder drop, W,...
Web width, W2... Width of mold surface.

Claims (1)

[Scope of Claims] 1. Using a bending mold having a curved band-shaped outer circumferential surface as a mold surface, a U-shaped cross-section member having a flat web and flanges bent in the same direction from both sides of the web is produced. The inner surface of the material is brought into contact with the mold surface of the bending mold, and the tension bending process is performed by wrapping the material around the bending mold, and the bending process is performed such that the shoulder part of the U-shaped cross section is dropped by the tension bending process. A method for bending a U-shaped cross-sectional material, characterized in that the width of the mold surface of the mold is narrower than the width of the web of the U-shaped cross-sectional material. 2. In claim 1, the bending mold has a groove on both sides of the mold surface into which the flange of the U-shaped cross-sectional member is inserted, and the groove has a groove in which the tip of the flange does not touch the bottom and the tip 1. A method for bending a U-shaped cross-section material, characterized by having a deep part that restricts movement in the width direction of the part. 3. The method of bending a U-shaped cross-section member according to claim 2, wherein the U-shaped cross-section member has a lip that projects in a direction that narrows the width of the opening at the tip of the flange.