JPS63108911A - Roll forming method and forming roll for edge bending - Google Patents

Abstract

PURPOSE:To correctly bend without reduced thickness by bending a stock to be formed with both edge faces of the stock compressed in the width direction to obstruct the metal flow to the outside in the width direction of the edge part. CONSTITUTION:Both edge faces of a stock 9 to be formed face to gate parts 4 formed on an upper roll 7', that is, the roll on the side to be the inner side of the stock 9. Then, by introducing the stock 9 in a roll gap having a development width shorter than that of the strip 9 itself, the contact end faces are subjected to a large compressive stress, and plastic flows are generated in the end parts by the stresses to prevent generation of thickness reduction and underfill. Thus, the structure and adjustment are simplified and the strength and stability are increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention accurately bends and forms a metal strip plate, which is ideal for bending and forming electric resistance welded pipes, up to both widthwise edges (hereinafter referred to as edges). This invention relates to a roll forming method and forming rolls used therein.

[Conventional technology]

When manufacturing an electric resistance welded tube from a metal strip, the material to be formed is also formed.In the conventional breakdown roll forming method, the outer edge corner of the material to be formed is formed as shown in steps B and C in FIG. There was a problem of wear due to crushing and sliding due to the line contact between the parts.

That is, in Figure B, after the flat material to be formed as shown in a starts contacting with the upper and lower breakdown rolls as shown in b, when it is sequentially bent and formed as (C1, (b)),
The corner on the outer peripheral side of the edge is the hole-shaped surface of the concave roll.
Since there is linear contact between the rollers, the material is crushed by high contact pressure, and the material to be formed is subjected to abrasion due to slipping in the longitudinal direction and width direction with the hole-shaped surface of the concave roll at these contact portions.

In addition, in the conventional breakdown roll forming method, bending in the width direction is impossible in the range of L≦(1,5 to 2.0) XT (T is the thickness of the material to be formed) from the edge surface of the material to be formed. It has been said that

In other words, the bending action by conventional breakdown rolls is due to the moment, 2 [arm length] x [force applied to the tip of the arm]. (distance to the surface) is small, so even if strong pressure is applied, only a part of the edge corner will be crushed and the wall thickness will be reduced, and sufficient bending action will not occur.For this reason, especially when T/D≧10
% (D: outside diameter of the pipe), as shown in Figure 4, the proportion of the incompletely bent portion to the total circumference increases, resulting in a decrease in the pressure resistance or mechanical strength of the pipe. It was remarkable.

Figure 4 shows the shape defects of the edge of the material to be formed just before welding, as described above.
．． The inner circumferential surface within the range of OT) is linear, and the outer circumferential surface has a crushed shape 1 during bending. These shape defects at the edges of the material to be formed have a significant effect on the success or failure of subsequent welding.

Figure 5 shows an example of the cross-sectional shape after welding.
3 and 3 are the thickened parts due to upsetting, but the outer diameter side of these thickened parts is usually removed by cutting etc., so the welded part is thinner than the other parts. The fact that the cross-sectional shape is far from a perfect circle is disadvantageous in terms of pressure resistance, especially in tubes that are subject to internal pressure.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION An object of the present invention is to provide a bending method that allows bending into a correct shape up to both edge surfaces, and a roll for the same.

[Means for solving problems]

The present invention is an edge bending method in which both edges of a material to be formed are bent while being compressed from the width direction in a breakdown bending method; To compress the material in the width direction, the material to be formed is made into a predetermined space by bending the center part of the material in the width direction so that the straight line spacing between both edge surfaces of the material is on the inner peripheral side of the material to be formed. This is done by inserting it between the weir-like parts provided on the side rolls and guiding it to a roll gap with a development width shorter than the development width of the material to be formed formed by this roll and another roll paired with this roll. .

Further, the present invention is a forming roll having the above-mentioned dish-shaped portion. This forming roll will become clear from the description below.

[For production]

In the conventional breakdown molding method, a part of the outer peripheral corner of the edge is easily crushed and deformed, resulting in underfilling.
This seems to be because the thickness of the edge of the material to be formed can freely flow outward in the width direction due to the compressive stress from the outer circumferential side, as shown in FIG. 6B.

Focusing on this point, the present invention actively compresses the edge surface to prevent the meat from flowing outward in the width direction of the edge, or conversely presses the edge to prevent the meat from flowing toward the inner circumference. This prevents wall thinning by changing the direction of the steel (Fig. A).

Further, in the present invention, the pressing of the edge surface is performed by a roll having a dish-shaped portion on the side that becomes the inner diameter of the material to be formed, and another roll that is paired with the roll, and the roll has a developed width smaller than the developed width of the material to be formed. When it is by leading to a gap,
There is no need for an edger roll or the like, and the roll structure is simple with upper and lower rolls like a normal roll stand, and there are no problems with strength, stability, or adjustment.

〔Example〕

1A and 1B show a comparison between the present invention and a conventional forming method, and a to e show each stage of the bending process in the roll stand with respect to FIG. 1B. .

In each figure, a indicates the cross-sectional shape of the material to be formed at the inlet of the roll stage, and in the conventional method, a flat plate shape is shown as an example. On the other hand, in the present invention, the straight line spacing (dimension 6) between both edge surfaces of the material to be formed is preliminarily bent to be narrower than a predetermined dimension by bending a portion excluding both edges (in short, the central portion of the plate width). It is something. This preliminary bending method may be performed by using 30 rolls as shown in FIG. 2, or by using normal upper and lower breakdown rolls that prevent crushing of both edges.

Part b shows the state in which the material to be formed has started contact with the forming rolls.The material to be formed is drawn in the same shape as in a, but in reality, at this stage, the material to be formed is moving around the upper and lower roll axes. The shape will be slightly different from this due to the influence of the cross-sectional shape (see d) in the plane containing the material (cross-section under tension). In the present invention, the material to be formed 9
Both edge surfaces face the dish-shaped portion 4 provided on the upper roll 7', that is, the roll on the inner peripheral side of the material to be formed 9.

In the conventional method, C indicates a state in which bending has progressed halfway, and in the present invention, the distance between both edge surfaces is expanded in the width direction by unbending at the center in the width direction, and the dish-shaped portions 4 have started to contact each other. show.

d shows the cross section under tension, and e shows the cross section at the exit of the roll. In the present invention, between C and d, the material to be formed 9 has both edge surfaces in contact with the dish-shaped portion 4, and is introduced between the roll gaps having a development width shorter than its own development width, so that the contact edge surface A large compressive stress is applied to the edge, and this stress causes a plastic flow toward a part of the inner corner of the edge, which prevents thinning and thinning. In the conventional method, C in d indicates that the edges freely produce a plastic flow outward in the width direction, so there is no bulge toward the inner corner and there is a lack of thickness.

In this example, as an edge surface compression method, the straight line spacing between both edge surfaces is preformed to be narrower than a predetermined dimension by bending the center part in the width direction. Since it is a combination of the bending and unbending of the central part in the width direction, the structure and adjustment are simple, and the structure is characterized by high strength and stability.

Next, FIG. 3 shows another embodiment of the present invention, in which it is applied to the so-called W-bend method. This W bend method is
The purpose is to make the edges, which are difficult to bend as described above, easier to bend by making them nearly perpendicular to the rolling direction, and bending the center part of the sheet width in the opposite direction to the circular tube. It is something to do.

This embodiment uses a pair of rolls including the unbending portion of the dimension W of the reversely bent portion at the center and a roll having a dish-shaped portion.

Application of the present invention to this W-bending method is suitable when emphasis is placed on the pressure applied from the front and back surfaces as opposed to the pressure applied to the edge surface.

〔Effect of the invention〕

As described above, the present invention is based on the conventional L≦(1,5 to 2.0
) XT, which makes it possible to correctly bend and form parts that cannot be bent, without thinning.In particular, it prevents a decrease in strength, and uses seamless pipes, which are difficult to use with conventional ERW pipes and are expensive. This opens the door to the application of electric resistance welded pipes to fields that require high strength and high wall thickness, and has a very large industrial effect.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the present invention in comparison with a conventional molding method, Fig. 2 shows an example of preforming of the invention, and Fig. 3 shows another embodiment of the invention. Figures 4 and 5
The figure is a diagram illustrating irregular cross-sectional shapes that occur in the conventional molding method, Figure 6 is a diagram illustrating the effect of the present invention in comparison with the conventional molding method, and Figure 7 is the deformation stage of the conventional molding method. FIG. 1: Collapsed part, 2, 3: Thickened part due to absent, 4: Dish-shaped part, 7.7': Upper roll, 8: Lower roll, 9: Material to be formed. B A Figure 2 Figure 4 Figure 5 A Figure 6 Figure 7

Claims (1)

[Claims] 1. In a breakdown bending method in which a metal strip is passed longitudinally through a large number of rows of roll stands and both edges are bent in the width direction, both edge surfaces of the material to be formed are A method for edge bending roll forming, characterized in that the material to be formed is subjected to the bending while being compressed from the width direction of the material. 2. Compression of the material to be formed in the width direction is performed by bending the linear distance between both edge surfaces of the material to be formed to a predetermined distance in the width direction by bending the portion of the material to be formed excluding the both edges, and compressing the material in the width direction. It is inserted between the weir-like parts provided on the roll on the inner peripheral side of the molded material, and has a developed width shorter than the developed width of the molded material formed by this roll and another roll paired with this roll. The edge bending roll forming method according to claim 1, characterized in that the method is carried out by introducing the material into a roll gap. 3. In a breakdown roll that passes a metal strip longitudinally through a large number of rows of roll stands and bends both edges of the strip in the width direction, one of the rolls has a surface that is the inner circumferential side of the material to be formed. An edge bending forming roll characterized by having a roll hole-shaped surface in contact with the roll hole-shaped surface and a weir-like roll hole-shaped surface adjacent to the roll hole-shaped surface in contact with the edge surface of the material to be formed.