JPH0312975B2 - - Google Patents

Description

Detailed Description of the Invention Field of Application This invention relates to the production of electric resistance welded steel pipes, that is, the production of steel pipes by continuous roll forming. A new forming roll system used in each forming step, such as, can manufacture steel pipes of various diameters and wall thicknesses from small diameter pipes to large diameter pipes with one set and one type of forming rolls without replacing the forming rolls. Although it is possible to form a conforming steel strip and the roll can be used in a very wide range, for example, when used as a forming roll for bending the ends of a steel band, the end bending of the steel band can be carried out sufficiently and reliably. In addition, as a forming roll at the center of the steel strip, it can make line contact with the bent end portion of the steel strip, which reduces roll surface pressure and has excellent formability into the required circular shape, and is effective in correcting insufficient or defective end bending in the previous stage. The present invention relates to a forming roll for pipe mills which can be used widely and which also has the effect of preventing rolling of materials to be formed.

BACKGROUND TECHNOLOGY Currently, straight seam welded steel pipes are manufactured using so-called continuous roll forming, in which a steel strip is continuously formed by using forming rolls suitable for forming the required diameter and wall thickness, and arranging the forming rolls according to the diameter. ERW steel pipes are the mainstream and are ideal for mass production of small quantities.

As shown in FIG. 10, the entire process of pipe making by continuous roll forming is roughly divided into a forming area of the end of the steel strip, a forming area of the center of the steel strip, and a forming area of the fin pass area.

That is, first, the breakdown roll (same b
(Fig.), initial forming is performed from bending the end of the steel band to a semicircle. Next, the non-driven side roll cluster (Fig. c) and/or horizontal rolls are used to form the steel strip into a nearly circular shape, forming a so-called fin. Pass roll (Figure d)
The angle of the edge surface is adjusted, reduced, finished formed, and centered, and then the welding process is started using a squeeze roll.

In addition, in the above process, the forming rolls are usually formed by arranging various combinations of horizontal and side rolls, and furthermore, in order to prevent buckling and edge waves due to edge stretching that occurs when forming thin-walled pipes, A cage forming method in which a large number of small flat rolls called cage rolls are arranged is also used.

In all conventional continuous roll forming methods, the main process is to form semicircular shapes at the initial stage of forming, which is the most difficult process, but the bending of the ends of the steel strip affects the roundness of the tube and the quality of the welding process. is insufficient.

In general, although there is a lot of spring back after passing through the rolls due to insufficient bending of the ends of the strip, it is common practice to increase the number of forming stages and avoid completely bending the ends of the strip, mainly due to manufacturing cost requirements. The idea is to form the central part of the steel strip and correct any formability defects in the early and middle stages of forming at once in the fin pass area.

For example, for the purpose of sufficient initial forming, a technique has been proposed in which the central part of the steel strip is back-bent, both ends are bent inward, and then the back-bend is returned to its original state (Japanese Patent Publication No. 59-27654, 59-150620), but
It cannot be said that the initial forming is still sufficient to eliminate the need for the above-mentioned corrections, and the forming rolls have almost no commonality with respect to changes in pipe diameter and wall thickness.

Therefore, an increase in the amount of molding in the fine pass region due to poor formability in the initial and middle stages of molding is undesirable from the perspective of the distribution of molding amount in the entire process, considering product accuracy, manufacturability, and economical efficiency of the molding equipment. .

In addition, insufficient bending of the strip ends and so-called squaring during the middle stage of forming affect the roundness of the pipe and the quality of the welding process, so forming at the stage of bending the ends of the strip can be carried out satisfactorily, or in the next stage. There has been a strong need for a forming method or forming device that can compensate for the lack of edge bending and prevent angular formation.

Furthermore, as mentioned above, manufacturing welded steel pipes by continuous roll forming requires the use of forming rolls suitable for forming the required diameter and wall thickness, the formation roll arrangement according to the diameter, and the width of the steel strip to be formed. It is necessary to replace the forming rolls depending on the size of the product, and it is not desirable from the viewpoint of manufacturing efficiency to prepare and replace a large number of forming rolls for each required diameter. Although it has been used for mass production, today there is a need to efficiently manufacture a wide variety of products using a single machine, and continuous rolls are suitable not only for mass production of a small number of products, but also for production of a wide variety of products in small quantities. A molding method or molding device is required.

In addition, in double radius forming, if the pipe diameter changes, the curvature of the bent end changes, so if the roll is shared, the bent end cannot be rolled down, and the circular part should be rolled with a straight roll or relatively Since the roll is rolled down while making point contact with a roll having a large radius of curvature, there is a problem that the formability into a circular shape deteriorates and angularity tends to occur.

Furthermore, when a large number of cage rolls are used in common, it is necessary to use a flat roll as well, which poses a problem in that the strip material to be formed tends to roll.

On the other hand, Japanese Patent Publication No. 57-46926 describes a forming roll for rough forming (breakdown) for the purpose of sharing the roll for several types of pipe diameters, for bending the ends of the strip steel of the planned maximum diameter pipe. Required curved surface R ₃ , the curved surface required for bending the end of the strip of pipe with the planned minimum diameter
R ₁ , curved surface R ₂ of the bending radius necessary for rough forming of the inner curved surface following the end of the strip steel of the pipe with the minimum diameter, from the outside of the roll surface to the inside in the order of curved surface R ₃ , curved surface R ₁ , and curved surface R ₂ A rough-forming roll having a roll surface arranged in the following manner has been proposed.

Forming using this rough forming roll is basically edge forming, and the purpose is to share the roll within several types of pipe diameter ranges, and three types of roll curved surfaces are used based on the maximum and minimum pipe diameters in the shared range. As in the conventional method, multi-stage molding is essential in order to determine , the idea is to make corrections all at once in the fine path area.

Problems with the conventional technology Therefore, as a result of examining the conventional technology for the purpose of forming pipes with a certain range of outer diameter and wall thickness using a common roll in continuous roll forming, we found that there is no forming method that has the same purpose. There are the following methods.

1 Cage roll forming method 2 Linear forming method 3 VRF method 4 CTA method In each of the conventional methods, the rolls used to form semicircular arc shapes based on roll flowers are: In the case of 1, circular forming is the basic method. In case 2, a large number of flat rolls are used as the basic method. In case 3, a large number of flat rolls are used with UO forming and center forming as the basic method. In case 3, circular forming with flanges is used as the basic method. In the case of 4, which uses a weight-shaped roll, the basic method is circular forming, and a combination of concave arc rolls is used instead of the flat roll of 1.

In either method, edge bending is basically not performed at the initial stage of molding, and when edge bending is required, it is carried out using a dedicated roll set.

Therefore, both conventional forming methods
It has not been possible to bend the ends of a steel strip suitable for manufacturing steel pipes of a wide variety of diameters and wall thicknesses, from small diameter pipes to large diameter pipes, with a single type of forming roll.

Purpose of the Invention In view of the above-mentioned current situation, the present invention has been devised to form a welded steel pipe by continuous roll forming, in which the center part of the steel strip is formed from the end bending of the steel strip to the subsequent approximately circular shape without replacing the forming rolls. With a set of forming rolls and one type of forming roll, it is possible to form steel pipes with a wide range of diameters and wall thicknesses from small diameter pipes to large diameter pipes, and it is possible to reliably bend the ends of the steel strip, or to form the ends in the center. The purpose of the present invention is to provide a forming roll that can be used in a wide range of applications for pipe mills, making up for insufficient bending, preventing angulation, and producing steel pipes with excellent shapes.

Summary of the Invention The present invention is a forming roll used in a forming area of a required part of a steel band when manufacturing a pipe from a steel band by continuous roll forming, and in which the direction of contact of the forming roll is adjusted to the direction of the object to be formed at a required forming stage. In order to form the strip on a part or all of the roll surface so that it can be changed according to the width of the strip, part or all of the cross-sectional curve of the roll surface can be changed according to the width of the roll of each roll flower of steel pipes with various outside diameters in the forming area. This forming roll for a pipe mill is characterized in that it has a cross-sectional curve consisting of an expansion curve set in advance so as to include each curved surface of a required portion of the steel strip.

Structure of the Invention In general, in continuous molding, it is important to consider how to burden the molding amount with a multi-stage stand. Considering this, consideration has been given to reducing edge stretching.

For example, in the above-mentioned rough forming (forming area of the end of the strip), the number of forming stages n is set, and the forming rolls of each stage are sequentially reduced in bending radius. , each has a roll surface consisting of a single circular arc with a required radius R or the aforementioned two to three circular arcs.

Therefore, when bending the vicinity of the end, it is essential to use a forming roll whose cross-sectional shape has a curvature adjusted to match the product pipe diameter, and it is impossible to use the same roll for forming different pipe diameters. It is.

In other words, in all conventional forming methods, forming is performed in multiple stages using a roll surface consisting of a single arc or two to three arcs as described above, but in actual forming, the cross-sectional shape of the strip is Rather than a circular arc,
Since it is considered to be a curved surface shape in which the curvature changes continuously, out of the countless imaginable curvatures, it is necessary to mold only on a curved surface with an approximate and only one or a few curvatures, as mentioned above. As such, the moldability into the desired shape was poor, and significant molding corrections in post-processes were essential.

Furthermore, considering the improvement of moldability, it is conceivable to significantly increase the number of molding stages, but this would be completely contrary to the desired molding efficiency, economic efficiency, or shared use of molding rolls.

Therefore, the inventors considered constructing the roll surface of the forming roll with a curved surface having a large number of curvatures in order to approximate the above-mentioned actual or ideal forming.

However, simply or randomly combining a large number of curvature surfaces does not provide excellent formability and common use of forming rolls.As a result of various studies on this issue, we found that combining a large number of curvature surfaces in a continuous manner with a certain relationship cannot be achieved. It was found that a roll surface consisting of a curved surface with multiple or countless groups of curvatures with varying curvatures is optimal.

To explain in more detail, first, assuming that the forming method in which plastic deformation of the steel strip is the most natural, then in order to continuously form the steel strip into a tube with a predetermined outer diameter by continuous roll forming, the forming method is the most difficult to form. The ends of the steel should be bent to fit the specified outer diameter from the beginning, but it is more natural to gradually bend and form the parts other than the ends of the steel strip, that is, from the ends to the center. It was considered that the most preferable roll curved surface of a forming roll suitable for forming is one in which the curvature becomes gradually gentler from the point where it abuts the end of the steel strip.

On the other hand, if we assume that the roll surface of the forming roll is composed of curved surfaces with multiple curvatures for the purpose of using the roll commonly for forming different pipe diameters as mentioned above, it is possible to easily form any pipe diameter. It needs to be well bent and formed.

In addition, since the ends of the strip steel are the most difficult to form,
As mentioned above, all conventional continuous roll forming methods are based on the premise of using a forming roll dedicated to the end of the steel strip according to the target outer diameter, but the forming of the end of the steel strip is performed in the initial stage of forming using a shared roll. If this could be done, the central part of the steel strip could be formed relatively easily in the middle stage of forming by using the forming curved surface of the end of the steel strip of this shared roll.

Therefore, there are various questions as to whether the roll surface of the forming roll, which has a continuous gentle curvature from the point where it contacts the end of the steel strip to the center, which is considered the most natural forming method, can be applied to the above-mentioned purpose of sharing the roll. As a result of our investigation, we found that a roll surface consisting of a curved surface with multiple or innumerable groups of curvatures with a certain relationship selected according to the common range and a continuous gentle curvature is the best, and this idea is based on the above idea. It has been found that the present invention can be applied not only to the forming stage of the end of the steel strip, but also to any forming roll used in any forming area of continuous roll forming.

Generally, the curvature of the end of a steel strip cannot be formed into a uniform radius even if it is formed by a roll having an arcuate surface due to the influence of spring back. That is, since the moment arm becomes shorter as it approaches the edge, the shape of the edge bending after springback becomes gentler in curvature as it approaches the edge.

Therefore, it has been found that if the curved surface is formed with a radius of curvature that becomes smaller as it approaches the end, the curvature will be close to uniform after springback.

When performing edge bending to form tubes with different outer diameters using a shared roll, it is possible to use an involute curved roll with a radius of curvature within a certain range.
The molding curvature can be changed by changing the location in contact with the molding material. In other words, it is possible to perform molding with different curvatures using a shared roll.

The roll surface consisting of a curved surface with a plurality of curvatures or innumerable groups of curvatures whose curvature changes continuously according to the above knowledge, as shown in FIGS. This is a roll surface consisting of an expansion curve set in advance to include each curved surface of the end of the steel strip in the roll flower of each steel pipe for forming steel pipes of various outer diameters.

Such an expansion curve is one in which a large number of continuous curvatures are formed so that part or all of the cross-sectional curve of the roll surface includes the curve of the required part of the strip steel of each roll flower of steel pipes with various outside diameters in the forming area. changing curved surface,
That is, it is made up of expansion and expansion curves used as evolutes such as circles, curves, polygons, etc., which are assumed to change the curvature of the roll surface continuously at a preset rate of change.

Therefore, for example, in addition to actually obtaining it from a roll flower diagram, it may be a regular expansion curve based on a certain base circle, or it may include a expansion curve based on the above-mentioned circle or ellipse. It may be a curve.

As mentioned above, if we consider that the curvature of the cross-sectional shape of the strip material changes continuously during molding, then assuming a curved surface that follows all of the curvatures, this is the basis of the approximate expansion curve in this invention. The polygon is a polygon with a very large number of sides. For example, if the base is a regular polygon, it can converge to a certain circle,
This is because an expansion curve based on the circle may be included.

For example, the forming roll according to the present invention can include all curved surfaces necessary for end bending among curved surfaces whose curvature changes continuously, so that end bending can be completed with good formability in one stage of forming. In addition, it is possible to have multiple stages if necessary, and the roll surface of each forming roll can be approximately stretched to have a curved surface that is assumed in consideration of forming workability, efficiency, roll manufacturability, etc. It may be provided continuously to the open curve.

In addition, the forming roll according to the present invention can set a curved surface whose curvature changes continuously, which is necessary for forming, in one roll surface assuming many different pipe diameters, so that the forming roll can be shared. , only the curved portion necessary for forming the required pipe diameter can be used.

Effects of the Invention By using the forming roll according to the present invention, for example, in forming the forming area of the end of a band, both ends of the band are each formed by a pair of upper and lower forming rolls whose cross section is the expansion curve. Shape this into 1
When forming in stages or in multiple stages, the distance between the pair of forming rolls at both ends of the strip is changed according to the width of the strip,
If necessary, use a roll that bulges the center part of the strip upward, and change the rolling direction of at least the upper forming roll of each forming roll set, so that the rolling direction is set in advance according to the width of the strip to be formed and the required end bending stage. It is possible to carry out a method of forming the end portion of a strip material in a pipe mill in which the end portion of the strip material is formed on a part or the entire surface of the expansion curve of the cross-sectional shape of the forming roll.

In other words, the method of forming the ends of a strip material using forming rolls according to the present invention can be used to form a wide range of diameters and thicknesses from small diameter pipes to large diameter pipes with one set and one type of forming rolls without replacing the forming rolls. It is possible to form the ends of the strip material to suit the production of thick steel pipes.
In addition, the influence of spring back can be reduced, the formability in the initial stage of forming in a pipe mill can be significantly improved, and the number of defects at the end can be reduced.

Furthermore, by using the forming roll according to the present invention, in forming the forming area at the center of the strip after bending the end of the strip, the bent end of the strip can be formed by side rolls having the stretching curve as a cross-sectional shape. When forming the strip into a substantially circular shape by arranging the side rolls in one or multiple stages, the distance between the pair of side rolls is changed according to the width of the strip, and the contact direction of each side roll is It is possible to perform a method of forming the center of the strip in a pipe mill by changing it according to the width of the forming strip and the required forming stage, and forming the center part of the strip on a part or the entire surface of the approximate elongation curve of the preset cross-sectional shape of the side roll. Depending on the forming stage, a forming method can be implemented in which an intermediate roll that contacts the center of the strip from above and/or a horizontal roll that contacts the center of the strip from below are used.

That is, the method for forming the center part of a strip using the forming roll according to the present invention uses only the side rolls having the above-mentioned shape, or in combination with an upper intermediate roll and/or a lower horizontal roll that can come into contact with the center of the strip. By doing so, it is possible to form the center of the strip suitable for manufacturing steel pipes of a wide range of diameters and wall thicknesses, from small diameter pipes to large diameter pipes, using one set and one type of forming rolls without replacing the forming rolls. It is possible to correct the bending of the end of the strip material, reduce the influence of spring back, and significantly improve the formability in the initial and middle stages of forming in the pipe mill. By reducing the amount of molding in the fin pass region, continuous roll forming with excellent molding distribution and formability is possible.

Further, the forming roll according to the present invention can be used in all forming steps in a pipe mill, and has the advantage that the number of forming stages and/or the number of forming rolls can be reduced, and the forming roll does not need to be replaced.

Furthermore, at each stage of the above-mentioned strip edge forming and/or strip center forming region, the functions of known horizontal rolls, side rolls, upper and lower intermediate rolls, or cage rolls, whether driven or non-driven, are used. It can be used as a roll with a It is possible to select and use them as appropriate, such as using them alternately with other forming rolls.

Disclosure of the Invention Based on Drawings FIG. 1a, FIG. 2, and FIG. 3 are explanatory diagrams of forming rolls used in the forming method of the present invention, showing a lower roll, a side roll, and an upper roll, respectively. FIG. 1b is an explanatory diagram showing the preset polygon a ₁ in FIG. 1a.

FIG. 4, FIG. 5, and FIG. 6 are explanatory diagrams showing side rolls and intermediate rolls according to the present invention. 7th
The figure is a front view of a steel strip end forming apparatus using forming rolls according to the present invention.

FIG. 8 is an explanatory view of the forming roll showing the forming roll closest to the forming roll in the width direction of the strip steel. FIG. 9 is a front view of a forming apparatus for forming the center of a steel strip using forming rolls according to the present invention.

In this invention, for example, as shown in FIGS. 7 and 8, the forming roll for bending the ends of a strip steel is capable of bending the ends of a large diameter pipe and a small diameter pipe with one forming roll. In the drawings, a wide cross-sectional curve is shown so that part or all of the cross-sectional curve of the roll surface of the upper and lower forming rolls 5, 18 includes the curve of the end of the steel strip 10 in each roll flower of steel pipes with various outside diameters set in advance. When bending the end of the steel strip 10, the curved surface of the lower side of the lower forming roll 5 is formed, and when bending the end of the narrow steel band 10, the roll surface includes the upper curved surface of the lower forming roll 5. , the forming rolls are moved so that the required curved surface is at a predetermined position according to the required diameter, that is, the width of the steel strip. Not only the movement of the upper roll but also the change of the direction of the roll surface needs to be performed at least only on the upper roll.

In addition, the forming roll for the center part of the steel strip is designed so that it is possible to bend the ends of the steel strip of a large-diameter pipe and a small-diameter pipe with one forming roll, as shown in Figs. 4, 5, and 6. 4, so that part or all of the cross-sectional curve of the roll surface of the forming roll 29 disposed on the side includes the curve of the end of the steel strip in each roll flower of steel pipes with various outside diameters set in advance. As shown,
When forming the center of the wide steel strip 10, the forming roll 2
In addition, when forming the center part of the narrow steel strip 10 shown in FIG. According to this, the forming roll is moved so that the required curved surface is at a predetermined position.

It is also possible to use it for an upper intermediate roll that contacts the center of the steel strip from above. Based on the same concept, a part or all of the cross-sectional curve of the roll surface of the intermediate roll 10 can be set at various outside diameters set in advance. In order to include the curve of the center of the steel strip 10 in each roll flower of the steel pipe, the roll is made into two parts that can approach and separate in the width direction of the steel strip, depending on the required diameter, that is, the width of the steel strip,
It is desirable to move it in the width direction and up and down so that the required curved surface is at a predetermined position.

As mentioned above, in order to expand the range of common use, the forming roll of the present invention has a roll surface of a specific shape, and a required curved surface is appropriately selected according to the diameter of the roll surface, that is, the forming roll side is moved. hand,
The idea is to match the end of the steel strip to be formed.

To be more specific, in the production of pipes of many different diameters, for example, in a certain forming step, a continuous smooth curved surface that includes all the many types of circular arcs necessary for forming the ends of various steel strips is formed on the roll surface. In order to give to
As a result of various studies, we found that a so-called expansion curve is appropriate.

In other words, a conventional forming roll with a curved surface such as a double radius cannot be used as a common roll, but if the roll surface is given an expansion curve based on a circle, the forming roll can be used in a much wider range of common uses. Furthermore, as shown in the examples, as a result of further studies in search of a forming roll that can be used in a wide range of applications, and which can be used to make pipes of dozens of different diameters, it was found that the required radius and length as described above were In order to obtain a continuous circular arc surface that includes all different types of circular arcs, for example, an expansion curve based on a polygon assuming the circular arcs as shown in Fig. 1 a, b, Fig. 2, and Fig. 3 is used. This invention was completed based on the knowledge that this must be the case.

In reality, such an expansion curve is obtained based on multiple sides consisting of various required opening angles θ _o , as shown in Fig. 1b, and the expansion curve is determined based on the required diameter type and wall thickness. , Depending on the bending part and stage, you can use only two sides to find an expansion curve based on an extremely large number of sides, such as arcs or circles.
There are various cases.

To give an example, generally speaking, as the number of sides of a polygon increases, it approaches a curve, and therefore the curvature of an expansion curve based on that curve changes continuously. Therefore, the necessary range of change in the curvature of the roll curved surface can be determined by defining a polygon or a curve and determining its expansion and expansion curve.

The roll surface of the forming roll is shown in Fig. 1a, Fig. 2,
To explain in detail the upper and lower rolls in FIG. 3, the roll surface of the forming roll has a preset polygonal shape ( The cross-sectional shape of the roll surface is an expansion curve based on α ₁ , α ₂ , α ₃ in the drawing, and the roll surface based on this specific expansion curve can be used to convert small diameter pipes to large diameter pipes. It corresponds to the curve of the edge of the steel strip or the curve of the center of the steel strip of a roll flower of steel pipes of various outside diameters and wall thicknesses in roll forming, and it is possible to contact and press the edge or center of the steel strip.

Furthermore, as described above, the forming roll according to the present invention has a polygonal shape with multiple sides, which is assumed to continuously change the curvature of the roll surface at a preset rate of change, including each curved surface at the end of the steel strip. It has been found that spring back at the ends of the steel strip can be prevented by making the cross-sectional shape of the roll surface an evolved expansion curve. To explain the mechanism in detail, in general, even if forming is performed using a roll with a curved surface of a constant curvature, the plate that curves along the roll curved surface during rolling will not be able to form. After passing through the rolls, it is shaped into a continuously changing curvature due to spring back.

In other words, with a forming roll having a curved surface of a constant curvature, the bending moment arm changes near the end of the strip during rolling and becomes close to zero, so the stress applied to the material changes depending on the strip width position. Therefore, it can be said that molding with a constant curvature is practically impossible.

However, if the curved surface is made to have a smaller radius as it approaches the end of the steel strip, even if spring back occurs, bending to a required constant radius becomes possible. The roll surface of the forming roll of this invention is shown in FIGS.
As shown in Figures 3 and 3, a polygon consisting of many sides is evoluted and the curvature of the roll surface is assumed to change continuously at a preset rate of change to include each curved surface of the end of the steel strip. Since the open curve has the cross-sectional shape of the roll surface, it is possible to form a curved surface with a smaller radius as it approaches the end of the steel strip, and has the effect that the end of the steel strip can be formed into a curved surface with a constant radius.

Therefore, in the process of bending the ends of the steel strip, sufficient bending of the ends may be carried out, or in the process of bending the ends of the steel band, the forming process of the center part of the steel strip may be started without sufficient bending of the ends. However, since the side roll according to the present invention has the above-described configuration and effects, it is possible to compensate for the lack of bending of the end portion of the strip at the same time as forming the center portion of the steel strip, and it is possible to form the steel strip into a circular shape with good shape.

In addition, as shown in FIGS. 1, 2, and 3, the cross-sectional shape of the roll surface is an expansion curve based on the aforementioned preset polygon, so that the ends of the steel strip are Since it is possible to form a curved surface with a smaller radius as it approaches the side rolls, the side rolls can make line contact with the bent end of the steel strip, thereby preventing rolling of the material to be formed. Moreover, when used as a cage roll, there is an advantage that the number of rolls can be reduced.

That is, continuous roll forming using the forming rolls according to the present invention can be carried out by using only the forming rolls having the shape described above or by using various combinations of conventional forming rolls, without replacing the forming rolls. In addition, with a single type of forming roll, it is possible to form pipes suitable for manufacturing steel pipes of a wide range of diameters and wall thicknesses, from small diameter pipes to large diameter pipes, and it is possible to compensate for bending of the ends of the strip steel, and the spring back It is possible to significantly improve the formability in the initial and middle stages of forming in a pipe mill, and reduce the number of defects at the end, reducing the amount of forming in the subsequent fin pass area, resulting in excellent forming distribution and formability. Continuous roll forming is possible.

The forming roll in this invention desirably includes:
The intervals between the upper and lower rolls, side rolls, etc. that contact both ends of the steel strip are changed according to the width of the steel strip, and the expansion curve of the roll cross-sectional shape set in advance is adjusted according to the width of the steel strip to be formed and the required forming stage. It is preferable to have a structure in which the roll surface is supported so as to be able to swing in an arc in the width direction of the steel strip so that it can come into contact with the end portion of the steel strip on one side or the entire surface.

The above explanation has shown examples of typical end bending rolls and side rolls of steel strip, but the forming roll according to the present invention can be used with any forming roll, whether driven or non-driven, in pipe mills having various configurations. It can also be applied to forming rolls for forming pipes of various metals and alloys, including steel strips.
Furthermore, the specific expansion curve constituting the roll surface of the forming roll according to the present invention is determined by the number of stages of roll types such as upper and lower rolls, side rolls, lower horizontal rolls, upper and lower intermediate rolls, etc., and the required number of rolls in various forming methods. It is recommended that the appropriate selection be made depending on various conditions such as the bore diameter, wall thickness, and molding distribution on the molding line.

EXAMPLES Example 1 FIG. 7 is a front view of a steel band end forming apparatus using forming rolls according to the present invention. FIG. 8 is an explanatory view of the forming roll showing the forming roll closest to the forming roll in the width direction of the strip steel.

The forming apparatus consists of a normal roll stand in which a lower roll shaft 3 and an upper roll support shaft 4 are arranged between U-shaped roll stands 2 erected on a base 1 at predetermined intervals.

The lower roll shaft 3 includes a pair of lower rolls 5, 5 and a two-part intermediate roll 6, 6 disposed between them.
It is positioned and fixed at a predetermined position in the axial direction via spacers 7 of various widths. This lower roll shaft 3 is here a drive shaft.

The upper roll support shaft 4 is connected to a pair of non-driven upper rolls 1.
8 and 18 vertically, and is screwed onto the upper end of the roll stand 2 in order to adjust the facing distance to the lower roll shaft 3 to cope with the thickness of the steel strip 10 and to increase or decrease the amount of rolling. A support shaft body 12 is connected to the screw shaft 11, which is clamped by a roll stand 2, so as to be movable in the vertical direction.

The upper roll support shaft 4 has a pair of beam members 13 arranged between a support shaft main body 12 held by the roll stand 2, and a rail 14 is attached to the lower surface of each beam member 11.

A saddle-shaped upper roll holding seat 16 is mounted on the rail 14 via a slide bracket 15 that can fit and slide on the rail 14, and is vertically held with its head inserted between the pair of beam members 13. ing.

The upper roll holding seat 16 has a downwardly facing inner surface forming a cylindrical seat surface 17 facing toward the rail 14 . Further, a U-shaped bearing member 1 that pivotally supports the upper roll 18 is provided.
A fan-shaped contact member that comes into contact with the cylindrical seat surface 17 is installed on the upper part of 9, and is slidably held between the cylindrical seat surfaces 17 by a fan-shaped receiving member fixed to the upper roll support seat 16. Ru.

A fan-shaped tooth surface is provided on the upper surface of the bearing member 19, and by driving the gear, the bearing member 19 of the upper roll 18 moves in an arc, and the roll surface of the upper roll 18 is moved in the width direction with respect to the steel strip 10. The structure allows the direction of contact to be changed.

In addition, each saddle-shaped upper roll holding seat 1 is provided so that the left and right pair of upper rolls 18 are close to each other and separate from each other in the drawing.
The nut member fixed to the head of 6 is moved by the rotation of the screw shaft.

On the other hand, the lower rolls 5, 5 and the intermediate rolls 6, 6
As mentioned above, the spacer 7 is attached to the lower roll shaft 3.
The upper rolls 18 and 18 are also configured to be able to change the width direction and the contact direction of the roll surfaces with respect to the steel strip 10.

Furthermore, upper rolls 18, 18, lower rolls 5, 5
And the intermediate rolls 6, 6 each have a roll surface within the required steel pipe outer diameter range, for example, from 89.1Φ.
Assuming that various steel pipes of 241.8Φ will be formed,
A polygon consisting of multiple sides was evolved, assuming that the curvature of the roll surface changes continuously at a preset rate of change to include each curved surface of the end of the steel strip in each roll flower of various outer diameter steel pipes. It consists of a forming roll whose cross section is an expansion curve.

The forming apparatus according to the present invention having the above-mentioned configuration can be used, for example, when bending the ends of a steel strip in forming a relatively large diameter steel pipe, as shown in FIG. In other words, the interval between the rolls is changed according to the width of the steel strip 10 so that a pair of upper rolls 18 and five sets of lower rolls are positioned, and furthermore, the direction in which the upper rolls 18 contact the steel strip 10 in the rolling direction is changed, Depending on the width of the strip steel 10 to be formed and the required end bending stage, that is, whether the end bending is completed in one stage or divided into multiple stages, the required curved surface portion of the stretching curve of the preset forming roll cross-sectional shape, here, the center The end of the steel strip 10 is formed into a desired shape at the curved surface of the section.

In this case, intermediate rolls 6 are used to raise the central part of the steel strip and improve formability at both ends, but the interval between the pair of intermediate rolls 6, 6 also depends on the width of the steel strip and the forming stage. The selection will be made accordingly.

In addition, in the case of the smallest diameter of the assumed diameter,
As shown in the figure, the lower rolls 5, 5 and the intermediate rolls 6, 6 are arranged integrally without a spacer, and the abutment direction of the upper rolls 18, 18 is also changed to the opposite direction from the previous one, and set in advance. The end portion of the steel strip 10 is formed into a desired shape at a desired curved surface portion of the expansion curve of the forming roll cross-sectional shape, here the outermost curved surface portion.

As described in detail, the molding device according to the present invention has the following features:
With one set and one type of forming rolls, it is possible to bend the ends of a steel strip suitable for manufacturing steel pipes of a wide range of diameters, from small diameter pipes to large diameter pipes, without replacing the forming rolls.

Embodiment 2 FIG. 9 is a front view of a forming apparatus for forming the center of a steel strip using forming rolls according to the present invention.

The molding apparatus has a gate-shaped stand 22 erected on a base 21, and a slide frame 26 on which a pair of side roll supports 25 are placed, using column frames 23 at the center of the stands on both sides as a sliding support frame. Both ends of the column frame 23 are joined together, and the slide frame body 24 is supported by a pair of hydraulic jacks 26 fixed to the base so that it can be moved up and down.

A side roll support 25 that pivots the non-driven side roll 29 to enable a predetermined arc movement is slidably mounted on the slide frame 24, and a nut member 28 is attached to the bottom of the slide frame 24. A screw driven by a motor (not shown) built into both sides of the slide frame 24 that is fixed and screwed into a screw shaft 27 that is fixed inside the slide frame 24 and connected to the column frame 23. As the shaft 27 rotates, the side roll support 25 moves in the axial direction, that is, in the width direction of the steel strip, and the side rolls 29 move in the width direction of the steel strip. 2
The threading directions of the screw shafts 28 with which the nut members 28 fixed to the bottoms of the respective supports 24 engage are opposite to each other so that the screw shafts 28 are engaged with each other so that the screw shafts 28 are engaged with each other so that the nut members 28 fixed to the bottoms of the respective supports 24 are engaged with each other.

The upper intermediate roll 30 is composed of a non-driven two-part roll, with a spacer (not shown) in between so that the distance between the pair of rolls can be adjusted, and the facing distance can be adjusted with respect to the vertically movable slide frame 24. In order to cope with the thickness of the strip steel and to increase or decrease the amount of contact, the shaft supporting member 32 of the upper intermediate roll 30 is connected to the screw shaft 31 screwed onto the upper end of the gate-shaped stand 22. It is configured so that it can be held in place and moved in the vertical direction.

The roll holding seat 33 fixed within the side roll support 25 has a lateral inner surface forming a vertical cylindrical seat surface 34 . A fan-shaped contact member that contacts the cylindrical seat surface 34 is installed on the upper part of the U-shaped bearing member 35 that supports the side roll 29,
A fan-shaped receiving member fixed to the roll holding seat 33,
It is slidably held between the cylindrical bearing surfaces.

Further, a fan-shaped tooth surface is provided on the upper surface of the bearing member 35 (not shown), and by driving the gear, the bearing member of the side roll 29 moves in an arc, and the roll surface of the side roll 29 is attached to the end-bent steel strip. On the other hand, the structure is such that the direction of contact can be changed in the width direction.

Further, the pair of side rolls 29 and the upper middle roll 30 each have a roll surface that can be used to form various steel pipes with various outside diameter widths, for example, from 89.1Φ to 241.8Φ. The curvature of the roll surface is assumed to change continuously at a preset rate of change to include each curved surface of the bent end of the strip steel or the center of each roll flower. It consists of a forming roll whose cross section is an open curve.

The forming apparatus according to the present invention having the above-mentioned configuration is used, for example, when bending the ends of a steel strip in forming a relatively large diameter steel pipe, as shown in FIG. but,
The interval between the 30 sets of upper intermediate rolls is changed according to the width of the steel strip so that the 30 sets of upper intermediate rolls are located at the center of the steel strip, and further,
By changing the direction of rolling of the side rolls 29 and the direction of contact with the steel strip, the cross-sectional shape of the roll surface is preset according to the width of the steel strip to be formed and the required forming stage, that is, whether the forming is completed in one step or divided into multiple steps. A required curved surface portion of the expansion curve contacts and embraces the bent end portion of the steel band, thereby forming the steel band into a desired circular shape.

In this case, the interval and vertical position of the pair of upper intermediate rolls 30 that are brought into contact with the center of the steel strip are also appropriately selected depending on the width of the steel strip and the forming stage.

The above explanation covers the relatively early and middle stages of the forming process of the center of the steel strip as shown in FIGS. 4 and 5, and the stage where the roll surface of the side rolls 29 changes from upward to sideways; In other words, it is about 1/2 yen or 2/3 yen from the stage equivalent to end bending.

Furthermore, when forming from this stage to a substantially circular shape, in place of the upper intermediate roll 30, as shown in FIG. However, the side roll 29 can be formed in a multi-stage manner in which the direction of rolling is changed stepwise from the above-mentioned horizontal direction to downward direction, and,
From the perspective of the material to be formed, the end of the steel strip is always held and formed into the desired circular shape by the side rolls 29, which match the bending shape of the steel strip. It can be seen that it has excellent moldability.

As described in detail, the molding device according to the present invention has the following features:
With one set and one type of forming rolls, it is possible to form steel strips suitable for manufacturing steel pipes of a wide range of diameters, from small diameter pipes to large diameter pipes, without replacing the forming rolls.

As shown in FIG. 1, the side roll surface has a cross-sectional shape of the roll surface with a specific expansion and expansion curve according to the present invention, so the closer it is to the end of the steel strip, the smaller the radius of the curved surface can be. Because of this, the side rolls can hold the bent end of the strip in line contact, preventing rolling of the material to be formed, and also correcting the bending of the end of the strip, reducing the effects of spring back. It is possible to significantly improve the moldability in the initial and middle stages of molding in a pipe mill.

[Brief explanation of the drawing]

FIGS. 1a, 2, and 3 are explanatory diagrams of forming rolls used in the forming method of the present invention, showing a lower roll, a side roll, and an upper roll, respectively. FIG. 1b is an explanatory diagram showing an expansion and expansion curve based on the preset polygon α ₁ in FIG. 1a. FIG. 4, FIG. 5, and FIG. 6 are explanatory diagrams showing side rolls and intermediate rolls according to the present invention. FIG. 7 is a front view of a steel strip end forming apparatus using forming rolls according to the present invention. FIG. 8 is an explanatory view of the forming roll showing the forming roll closest to the forming roll in the width direction of the strip steel. FIG. 9 is a front view of a forming apparatus for forming the center of a steel strip using forming rolls according to the present invention. FIGS. 10a to 10d are explanatory diagrams of a pipe mill and forming rolls showing a conventional continuous roll forming method. 1...Base, 2...Roll stand, 3...Lower roll shaft, 4...Upper roll support shaft, 5...Lower roll, 6...Intermediate roll, 7...Spacer, 10
... Steel band, 11 ... Screw shaft, 12 ... Support shaft body, 13 ... Beam member, 14 ... Rail, 15 ...
...Slide bracket, 16...Top roll holding seat, 17...Cylindrical bearing surface, 18...Top roll, 19
... Bearing member, 21 ... Base, 22 ... Gate-shaped stand, 23 ... Column frame, 24 ... Slide frame, 2
5...Side roll support body, 26...Hydraulic jack, 27...Screw shaft, 28...Nut member, 29
...Side roll, 30...Top middle roll, 31
... Screw shaft, 32 ... Shaft supporting material, 33 ...
Roll holding seat, 34...Cylindrical seat surface, 35...Bearing member, 36...Lower horizontal roll.

Claims (1)

[Scope of Claims] 1. A forming roll used in a forming area of a required part of a steel band when manufacturing a pipe from a steel band by continuous roll forming, wherein the contact direction of the forming roll is set to the direction of the object to be formed at a required forming stage. In order to form the strip on a part or all of the roll surface so that it can be changed according to the width of the strip, part or all of the cross-sectional curve of the roll surface can be changed according to the width of the roll of each roll flower of steel pipes with various outside diameters in the forming area. 1. A forming roll for a pipe mill, characterized in that it has a cross-sectional curve consisting of an expansion curve set in advance so as to include each curved surface of a required portion of a steel strip. 2. The forming roll for a pipe mill according to claim 1, which is a pair of upper and lower forming rolls for bending the ends of a steel band. 3. A forming roll for a pipe mill according to claim 1, which is a forming roll for bending an upper or lower end of a steel band divided in the width direction of the steel band. 4. The forming roll for a pipe mill according to claim 1, which is a side roll. 5. The forming roll for a pipe mill according to claim 1, which is an upper or lower intermediate roll divided in the width direction of the strip steel. 6. The forming roll for a pipe mill according to claim 1, which is a cage roll.